Correction methods for noncontact intraocular pressure measurement in patients with keratoconus and healthy individuals / Métodos de correção para medição sem contato da pressão intraocular em indivíduos normais e com ceratocone

ABSTRACT Purpose: The objective of this study was to investigate the usefulness of four different algorithms to correct noncontact intraocular pressure measurement errors in keratoconus patients and normal individuals. Methods: Noncorrected intraocular pressure and corrected intraocular pressures were measured in one eye of 34 patients with keratoconus and 34 age- and gender-matched healthy controls using Corvis Scheimpflug Technology. The correlation of noncorrected intraocular pressure and corrected intraocular pressures with age, axial length, corneal shape, thickness, and biomechanics was calculated. Corrected intraocular pressures were compared with noncorrected intraocular pressure using paired t test and Bland-Altman plots (95% limits of agreement). Results: The noncorrected intraocular pressure correlated with corneal thickness and biomechanical parameters in both groups (all p≤0.047), and front and back mean keratometry in the keratoconus group (r=-0.39, p=0.02, and r=0.39, p=0.02, respectively). After adjustment with different intraocular pressure correction algorithms, biomechanically corrected intraocular pressure showed a minimal correlation with corneal features and a nonsignificant difference with noncorrected intraocular pressure in the healthy group (-0.1 ± 1.1 mmHg, p=0.58; 95% limits of agreement: -2.3 to 2.1 mmHg). Conclusions: Measuring intraocular pressure using noncontact tonometry and its corrected forms with a corneal thickness-based simple linear formula in patients with keratoconus is associated with many errors. Using more complex formulas that take into consideration more corneal stiffness parameters in addition to corneal thickness, such as biomechanically corrected intraocular pressure formula, may be more reliable and beneficial in this group of patients.

RESUMO Objetivo: Investigar a utilidade de quatro algoritmos diferentes para corrigir erros de medição sem contato da pressão intraocular em pacientes saudáveis e com ceratocone. Métodos: A pressão intraocular não corrigida e as pressões intraoculares corrigidas foram medidas em um olho de 34 pacientes com ceratocone e 34 pacientes do grupo controle saudável pareados por idade e gênero usando a tecnologia Corvis Scheimpflug. Foi calculada a correlação da pressão intraocular não corrigida e das pressões intraoculares corrigidas com idade, comprimento axial e formato, espessura e biomecânica da córnea. As pressões intraoculares corrigidas foram comparadas com a pressão intraocular não corrigida usando o teste t pareado, e gráficos de Bland-Altman (limites de concordância de 95%). Resultados: A pressão intraocular não corrigida correlacionou-se com a espessura da córnea e com os parâmetros biomecânicos em ambos os grupos (todos p≤0,047) e a ceratometria média frontal e posterior no grupo com ceratocone (r=-0,39, p=0,02, r=0,39, p=0,02, respectivamente). Após o ajuste com diferentes algoritmos de correção da pressão intraocular, a pressão intraocular corrigida biomecanicamente revelou uma correlação mínima com as características da córnea e uma diferença não significativa com a pressão intraocular não corrigida no grupo saudável (-0,1 ± 1,1 mmHg, p=0,58; limites de concordância de 95%: -2,3 a 2,1 mmHg). Conclusões: A medição da pressão intraocular usando tonometria sem contato e suas formas corrigidas usando fórmulas lineares, simples, baseadas na espessura da córnea em pacientes com ceratocone estão associadas a muitos erros. O uso de fórmulas mais complexas que consideram mais parâmetros de rigidez da córnea além da espessura da córnea, como fórmula de pressão intraocular corrigida biomecanicamente, pode ser mais confiável e benéfico neste grupo de pacientes.

Corneal structure and endothelial morphological changes after uneventful phacoemulsification in type 2 diabetic and nondiabetic patients / Alterações da estrutura e endotélio da cornea após facoemulsificação sem complicações em pacientes diabéticos tipo 2 e não diabéticos

ABSTRACT Purpose: The aim of this study was to compare corneal structure and endothelial morphological changes after uneventful phacoemulsification cataract surgery between type 2 diabetic and nondiabetic patients and to determine the preoperative and intraoperative factors that may predict greater endothelial cell density loss. Methods: Forty-five diabetic pa­tients (45 eyes) and 43 controls (43 eyes) with age-related cataract were enrolled in this prospective observational study. Corneal (thickness and volume) and anterior segment parameters were measured by Scheimpflug tomography; endothelial cell density and morphology (coefficient of variation of cell size, hexagonal cells) were recorded using noncontact specular microscopy. Patients were evaluated preoperatively and at one and six months after surgery. Univariate and multivariate linear regression analyses were performed to evaluate the relationship between demographic, clinical, ocular, and intraoperative parameters and postoperative endothelial cell density changes at six months. Results: Significant postoperative endothelial cell loss occurred one month after surgery in both groups (p<0.001), which remained stable until month 6; there were no differences between patients with and without diabetes mellitus at any time point. The mean postoperative central corneal thickness at one and six months did not change significantly from the mean preoperative value in either group (p>0.05). Multivariate linear regression analysis showed that older age (p=0.042) and higher cataract grades (p=0.001) were significantly associated with greater endothelial cell density reduction at six-month follow-up. Conclusion: This study showed that older age and denser cataracts might be associated with greater endothelial cell density reduction after cataract surgery. Other factors, such as diabetes mellitus and preoperative anterior segment parameters, did not influence postoperative changes in endothelial cell density.

RESUMO Objetivo: Comparar a estrutura da córnea e as alterações mor­fológicas endoteliais após cirurgia de catarata por facoemulsificação sem intercorrências entre pacientes com diabetes mellitus tipo 2 e não diabéticos; e determinar quais fatores pré e intra-operatórios relacionados com a maior redução da densidade celular endotelial. Métodos: Quarenta e cinco diabéticos (45 olhos) e 43 (43 olhos) controlos com catarata relacionada à idade foram incluídos neste estudo observacional prospectivo. Os parâmetros da córnea (espessura e volume) e do segmento anterior foram medidos pela tomografia Scheimpflug; a densidade e morfologia celular endotelial (coeficiente de variação do tamanho das células, células hexagonais) foram registrados usando microscopia especular não contato. Os pacientes foram avaliados no pré-operatório, 1 e 6 meses após a cirurgia. Foi realizada uma análise de regressão linear uni e multivariada para avaliar a relação entre os parâmetros demográficos, clínicos, oculares e intra-operatórios com a redução da densidade celular endotelial aos 6 meses. Resultados: Nos dois grupos houve uma perda significativa de células endoteliais ao 1º mês pós-ope­ratório (p<0,001), que permaneceu estável até ao 6º mês; sem diferenças estatisticas entre os grupos diabetes mellitus e não diabetes mellitus em qualquer avaliação. A espessura média da córnea no pós-operatório central aos 1 e 6 meses não mudou significativamente em relação ao valor médio pré-operatório nos dois grupos (p>0.05). A análise de regressão multivariada linear mostrou que a idade avançada (p=0.042) e os graus mais elevados de catarata (p=0.001) foram significativamente associados à maior redução densidade celular endotelial aos 6 meses de seguimento. Conclusão: Este estudo mostrou que a idade avançada e as cataratas mais densas podem predispor a uma maior redução densidade celular endotelial após a cirurgia de catarata. Outros fatores, como diabetes mellitus e parâmetros pré-operatórios do segmento anterior, não influenciaram significativamente as alterações pós-operatórias da densidade celular endotelial.

The effects of pharmacological accommodation and cycloplegia on axial length and choroidal thickness / Efeitos da acomodação farmacológica e da cicloplegia no comprimento axial e na espessura da coroide

ABSTRACT Purpose: To investigate the effects of pharmacological accommodation and cycloplegia on ocular measurements. Methods: Thirty-three healthy subjects [mean (±SD) age, 32.97 (±5.21) years] volunteered to participate in the study. Measurement of the axial length, macular and choroidal thickness, refractive error, and corneal topography, as well as anterior segment imaging, were performed. After these procedures, pharmacological accommodation was induced by applying pilocarpine eye drops (pilocarpine hydrochloride 2%), and the measurements were repeated. The measurements were repeated again after full cycloplegia was induced using cyclopentolate eye drops (cyclopentolate hydrochloride 1%). The correlations between the measurements were evaluated. Results: A significant increase in subfoveal choroidal thickness after applying 2% pilocarpine was identified (without the drops, 319.36 ± 90.08 µm; with pilocarpine instillation, 341.60 ± 99.19 µm; with cyclopentolate instillation, 318.36 ± 103.0 µm; p<0.001). A significant increase in the axial length was also detected (without the drops, 23.26 ± 0.83 mm; with pilocarpine instillation, 23.29 ± 0.84 mm; with cyclopentolate instillation, 23.27 ± 0.84 mm; p=0.003). Comparing pharmacological accommodation and cycloplegia revealed a significant difference in central macular thickness (with pilocarpine instillation, 262.27 ± 19.34 µm; with cyclopentolate instillation, 265.93 ± 17.91 µm; p=0.016). Pilocarpine-related miosis (p<0.001) and myopic shift (p<0.001) were more severe in blue eyes vs. brown eyes. Conclusion: Pharmacological accommodation may change ocular measurements, such as choroidal thickness and axial length. This condition should be considered when performing ocular measurements, such as intraocular lens power calculations.(AU)

RESUMO Objetivo: Investigar os efeitos da acomodação farmacológica e da cicloplegia nas medições oculares. Métodos: participaram do estudo 33 voluntários saudáveis (média de idade [± DP], 32,97 anos [± 5,21 anos]). Foram medidos o comprimento axial, a espessura macular e coroidal e o erro refrativo, bem como realizados exames de imagem da topografia corneana e do segmento anterior. Em seguida, foi induzida a acomodação farmacológica aplicando-se colírio de pilocarpina (cloridrato de pilocarpina a 2%) e as medições foram repetidas nos participantes. As mesmas medições foram repetidas depois de induzir a cicloplegia completa com colírio de ciclopentolato (cloridrato de ciclopentolato a 1%) e foram avaliadas as correlações entre as medidas. Resultados: Identificou-se aumento significativo da espessura coroidal subfoveal com o uso da pilocarpina a 2% (sem colírio, 319,36 ± 90,08 µm; com a instilação de pilocarpina, 341,60 ± 99,19 µm; com a instilação de ciclopentolato, 318,36 ± 103,0 µm; p<0,001). Detectou-se também aumento significativo do comprimento axial (sem colírio, 23,26 ± 0,83 mm; com a instilação de pilocarpina, 23,29 ± 0,84 mm; com a instilação de ciclopentolato, 23,27 ± 0,84 mm; p=0,003). Ao se comparar a acomodação farmacológica e a cicloplegia, houve diferença significativa na espessura macular central (com a instilação de pilocarpina, 262,27 ± 19,34 µm; com a instilação de ciclopentolato, 265,93 ± 17,91 µm; p=0,016). Observou-se que a miose associada à pilocarpina (p<0,001) e o desvio miópico (p<0,001) foram mais severos nos olhos azuis que nos castanhos. Conclusão: A acomodação farmacológica pode alterar medidas oculares como a espessura da coroide e o comprimento axial. Essa possibilidade deve ser levada em consideração ao se efetuarem medições oculares, tais como cálculos de potência de lentes intraoculares.(AU)

Effects of pupillary dilation on ocular optical biometry outcomes in pediatric patients / Efeitos da dilatação pupilar nos resultados da biometria óptica ocular em pacientes pediátricos

ABSTRACT Purpose: Pharmacological pupillary dilation is performed in comprehensive ophthalmological examinations and before biometric measurements. So far, there is no consensus regarding its impact on biometric measurements. This study's aim was to investigate the effects of pharmacological pupillary dilation on ocular biometric measurements in healthy children. Methods: This was a prospective, observational, non-randomized study of children (4-18 years of age) who were admitted for routine ophthalmological examination. Biometric measurements were performed, using a non-contact optical biometry device, both before and after pharmacological pupillary dilation with cyclopentolate hydrochloride. Intraocular lens power calculations were performed using Hill-RBF, Barrett, Olsen, Sanders-Retzlaff-Kraff/Theoretical, Holladay, and Hoffer Q formulas. Descriptive statistical analyses were also performed. The Wilcoxon signed-rank test was used to compare measurements before and after pharmacological pupillary dilation. Relationships between variables were analyzed using the Spearman-Brown rank correlation coefficient. Results: The study included 116 eyes of 58 children (mean age, 8.4 ± 0.32 years; 34 girls). Significant changes were observed after pupillary dilation, compared with before pupillary dilation, in terms of anterior chamber depth, aqueous depth, and central corneal and lens thicknesses. No significant change was observed in axial length. Intraocular lens power calculations revealed no significant changes after pupillary dilation in most formulas except for the Olsen formula. The intraocular lens power was significantly inversely correlated with axial length and anterior chamber depth. Conclusions: Pharmacological pupillary dilation in children appeared to have no impact on axial length and intraocular lens power, but caused a significant increase in anterior chamber depth. The difference in anterior chamber depth measurements before and after pupillary dilation could be related to the optical biometry device model used. These outcomes should be considered in intraocular lens power calculations performed using anterior chamber depth parameters.

RESUMO Objetivo: A dilatação pupilar farmacológica é realizada em exames oftalmológicos abrangentes e antes das medições biométricas. Até o momento, não há consenso sobre seu impacto nas medições biométricas. O objetivo deste estudo foi investigar os efeitos da dilatação pupilar nas medidas biométricas oculares em crianças saudáveis. Métodos: Estudo prospectivo, observacional e não randomizado de crianças (4-18 anos) que foram admitidas para exame oftalmológico de rotina. As medidas biométricas foram realizadas usando um dispositivo de biometria óptica sem contato, antes e após a dilatação pupilar farmacológica com cloridrato de ciclopentolato. Os cálculos de potência das lentes intraoculares foram realizados utilizando as fórmulas de Hill-RBF, Barrett, Olsen, Sanders-Retzlaff-Kraff/ Teórica, Holladay e Hoffer Q. Análises estatísticas descritivas também foram realizadas. O teste dos postos sinalizados de Wilcoxon foi usado para comparar as medidas antes e após a dilatação pupilar farmacológica. As relações entre as variáveis foram analisadas pelo coeficiente de correlação de Spearman-Brown. Resultados: O estudo incluiu 116 olhos de 58 crianças (idade média de 8,4 ± 0,32 anos; 34 meninas). Alterações significativas foram observadas após a dilatação pupilar, em termos de profundidade da câmara anterior, profundidade do humor aquoso e espessura central da córnea e do cristalino. Nenhuma mudança significativa ocorreu no comprimento axial. Os cálculos de potência da lente intraocular não revelaram alterações significativas após a dilatação pupilar na maioria das fórmulas, com exceção da fórmula Olsen. O poder da lente intraocular foi significativamente inversa correlacionada com o comprimento axial e a profundidade da câmara anterior. Conclusões: A dilatação pupilar farmacológica em crianças parece não ter impacto no comprimento axial e no poder da lente intraocular, mas causou um aumento significativo na profundidade da câmara anterior. A diferença nas medidas da profundidade da câmara anterior antes e após a dilatação pupilar pode estar relacionada ao modelo do dispositivo de biometria óptica utilizado. Tais resultados devem ser considerados nos cálculos de potência da lente intraocular realizados usando parâmetros de profundidade da câmara anterior.

Accelerated corneal cross-linking with hypo-osmolar riboflavin in thin keratoconic corneas: 2-year follow-up / Cross-linking corneano acelerado com riboflavina hiposmolar em córneas ceratocônicas finas: 2 anos de acompanhamento

ABSTRACT Purpose: This study was performed to evaluate the outcomes of accelerated corneal cross-linking in keratoconic corneas with thinnest pachymetry values of <400 µm. Methods: The study included 28 eyes of 24 patients. The uncorrected and best-corrected visual acuities (logMAR), flattest and steepest keratometric readings, central corneal thickness at the thinnest point, corneal higher-order aberrations, and contrast sensitivity were assessed before and at 1, 3, 6, 12, and 24 months after corneal cross-linking. Result: The mean best-corrected visual acuity and contrast sensitivity increased (p=0.02, p=0.03, respectively), whereas the mean uncorrected visual acuity did not significantly differ (p>0.05) at 24 months after corneal cross-linking, compared with measurements before corneal cross-linking. Although the mean flattest keratometric reading showed no significant change (p=0.58), the mean steepest keratometric reading was reduced when compared with its value before corneal cross-linking (p=0.001). No change was observed in the mean central corneal thickness at the thinnest point at 24 months after corneal cross-linking, compared with its value before corneal cross-linking (p=0.12). Conclusion: Accelerated corneal cross-linking in keratoconic eyes with thin corneas could halt the progression of keratoconus in corneas thinner than 400 µm at 24 months after treatment.

RESUMO Objetivo: Este estudo foi realizado para avaliar os resultados do cross-linking corneano acelerado em córneas ceratocônicas com os valores mais baixos de paquimetria <400 µm. Métodos: O estudo incluiu 28 olhos de 24 pacientes. As acuidades visuais não corrigidas e melhor corrigidas (logMAR), leituras ceratométricas mais planas e íngremes, espessura corneana central no ponto mais fino, aberrações corneanas de mais alta ordem e a sensibilidade ao contraste foram avaliadas antes e em 1, 3, 6, 12 e 24 meses após a realização do do cross-linking. Resultados: A média da acuidade visual melhor corrigida e a sensibilidade ao contraste aumentaram (p=0,02, p=0,03, respectivamente), enquanto a média da acuidade visual não corrigida não diferiu significativamente (p>0,05) aos 24 meses após o cross-linking, comparada com medidas antes do procedimento. Embora a leitura da média da ceratometria mais plana não tenha apresentado alteração significativa (p=0,58), a leitura ceratométrica mais íngreme diminuiu quando comparada ao seu valor antes do cross-linking (p=0,001). Não foi observada alteração na média da espessura corneana central no ponto mais fino aos 24 meses após o cross-linking em comparação com seu valor antes do procedimento (p=0,12). Conclusão: O cross-linking corneano acelerado nos olhos ceratocônicos com córneas finas pode interromper a progressão do ceratocone nas córneas mais finas que 400 µm 24 meses após o tratamento.

Does wearing swimming goggles affect corneal morphology in keratoconic eyes? / Uso de óculos de natação afeta a morfologia da córnea em olhos ceratocônicos?

ABSTRACT Purpose: A significant transient increase in intraocular pressure in individuals wearing swimming goggles has been demonstrated in previous studies. These findings suggested that wearing swimming goggles could represent a significant risk factor for worsening of corneal parameters in patients with keratoconus who swim regularly. The aim of this study was to investigate corneal parameters in patients with keratoconus after wearing swimming goggles. Methods: Comprehensive ocular examinations were performed on 74 eyes of 37 patients with keratoconus. Measurements of the corneal front keratometry values (Kflat, Ksteep, and Kmax), central corneal thickness, corneal apex thickness, thinnest corneal thickness, corneal volume, anterior chamber volume, anterior chamber depth, and iridocorneal angle were performed in outpatient clinics using a Pentacam® Scheimpflug camera (Oculus, Wetzlar, Germany) before the patients wore swimming goggles and after they wore swimming goggles for 1, 10, and 20 min. A p-value of <0.05 was regarded as statistically significant. Results: The average values before and after wearing swimming goggles for 1, 10, and 20 min were 52.72 ± 5.36, 52.64 ± 5.52, 52.62 ± 5.38, and 52.22 ± 4.86, respectively (p=0.257). The average values before and after wearing swimming goggles for 1, 10, and 20 min were 46.01 ± 3.17, 46.09 ± 3.17, 46.06 ± 3.26, and 46.04 ± 3.17, respectively (p=0.426). The average values before and after wearing swimming goggles for 1, 10, and 20 min were 49.02 ± 3.56, 49.06 ± 3.61, 49.08 ± 3.62, and 49.07 ± 3.61, respectively (p=0.750). No other corneal parameters showed changes after wearing swimming goggles (p>0.05). However, the anterior chamber volume markedly decreased after wearing swimming goggles (p<0.001). Conclusions: These findings suggested that the short-term use of swimming goggles does not increase the risk of corneal parameter worsening in patients with keratoconus.

RESUMO Objetivo: Um aumento transitório significativo da pressão intraocular em indivíduos usando óculos de natação foi demonstrado em estudos anteriores. Esses achados sugerem que o uso de óculos de natação pode representar um fator de risco significativo para o agravamento dos parâmetros corneanos em pacientes com ceratocone que nadam regularmente. O objetivo deste estudo foi investigar os parâmetros corneanos em pacientes com ceratocone após o uso de óculos de natação. Métodos: Foram realizados exames oftalmológicos completos em 74 olhos de 37 pacientes com ceratocone. As medidas dos valores de ceratometria frontal da córnea (Kflat, Ksteep e Kmax), espessura corneana central, espessura apical da córnea, espessura corneana mais fina, volume da córnea, volume da câmara anterior, profundidade da câmara anterior e ângulo iridocorneano foram realizados em ambulatórios usando câmera Pentacam® Scheimpflug (Oculus, Wetzlar, Alemanha) antes dos pacientes usarem óculos de natação por 1, 10 e 20 min. Um valor p<0,05 foi considerado estatisticamente significativo. Resultados: Os valores médios de antes e após o uso de óculos de natação por 1, 10 e 20 min foram: 52,72 ± 5,36, 52,64 ± 5,52, 52,62 ± 5,38 e 52,22 ± 4,86, respectivamente (p=0,257). Os valores médios do (antes e após o uso de óculos de natação por 1, 10 e 20 min foram: 46,01 ± 3,17, 46,09 ± 3,17, 46,06 ± 3,26 e 46,04 ± 3,17, respectivamente (p=0,426). Os valores médios de antes e após o uso de óculos de natação por 1, 10 e 20 min foram: 49,02 ± 3,56, 49,06 ± 3,61, 49,08 ± 3,62 e 49,07 ± 3,61, respectivamente (p=0,750). Nenhum outro parâmetro da córnea apresentou alterações após o uso de óculos de natação (p>0,05). No entanto, o volume da câmara anterior diminuiu acentuadamente após o uso de óculos de natação (p<0,001). Conclusões: Esses achados sugerem que o uso de óculos de natação a curto prazo não aumenta o risco de piora dos parâmetros corneanos em pacientes com ceratocone.

Relationships between corneal biomechanics and the structural and functional parameters of glaucoma damage / Relações entre a biomecânica da córnea e os parâmetros estruturais e funcionais do dano do glaucoma

ABSTRACT Purpose: To investigate the relationships between (i) thickness of the retinal nerve fiber layer, optic nerve head topography, and visual field parameters and (ii) corneal biomechanical properties in normal controls and patients with ocular hypertension and primary open-angle glaucoma. Methods: This observational, cross-sectional study included 68 eyes with primary open-angle glaucoma, 99 eyes with ocular hypertension and 133 control eyes. Corneal biomechanical properties, optic nerve head topographic features, retinal nerve fiber layer thickness, and visual fields were assessed in all cases. Corneal biomechanical properties, retinal nerve fiber layer thicknesses, and optic nerve head topographic features were compared among the groups. The associations between structural and functional measures of glaucomatous damage and corneal biomechanical factors were also evaluated. Results: Significantly lower corneal hysteresis and corneal resistance factor values were observed in the primary open-angle glaucoma and ocular hypertension groups as compared with the control group, but there were no significant differences between the primary open-angle glaucoma and ocular hypertension groups. In the ocular hypertension group, no associations were observed between the corneal hysteresis and corneal resistance factor with values and the structural and functional parameters. In the primary open-angle glaucoma group, positive correlations were observed between the corneal hysteresis values and the global retinal nerve fiber layer thickness (p<0.01, r=0.27), mean retinal nerve fiber layer thickness (p<0.01, r=0.33), and mean deviation (p<0.01, r=0.26), and negative correlations were observed between the corneal resistance factor values, and the cup area (p<0.01, r=-0.39), cup-to-disk ratio (p=0.02, r=-0.28), linear cup-to-disk ratio (p=0.02, r=-0.28), and cup shape (p=0.03, r=-0.26). In the control group, weak correlations were detected between the corneal hysteresis and the cup area (p=0.03, r=0.19), cup-to-disk ratio (p=0.01, r=0.21), and linear cup-to-disk ratio (p=0.01, r=0.22). Conclusions: Distinct correlations were identified between the corneal hysteresis and corneal resistance factor values and the functional and structural parameters in the primary open-angle glaucoma and control groups. Corneal hysteresis and corneal resistance factor may have different roles in the pathophysiology of glaucoma.

RESUMO Objetivo: Investigar as relações entre (i) espessura da camada de fibras nervosas da retina, topografia do nervo óptico e parâmetros do campo visual e (ii) propriedades biomecânicas da córnea, em controles normais e pacientes com hiperten são ocular e glaucoma primário de ângulo aberto. Métodos: Este estudo observacional, transversal, incluiu 68 olhos com glaucoma primário de ângulo aberto, 99 olhos com hipertensão ocular e 133 olhos controle. As propriedades biomecânicas da córnea, as características topográficas da cabeça do nervo óptico, a espessura da camada de fibras nervosas da retina e os campos visuais foram avaliados em todos os casos. As propriedades biomecânicas da córnea, a espessura da camada de fibras nervosas da retina e as características topográficas da cabeça do nervo óptico foram comparadas entre os grupos. As associações entre medidas estruturais e funcionais de danos glaucomatosos e fatores biomecânicos da córnea também foram avaliadas. Resultados: Valores de histerese corneana e da resistência corneana foram significativamente menores nos grupos com glaucoma primário de ângulo aberto e hipertensão ocular em com paração ao grupo controle, mas não houve diferenças significativas entre os grupos de glaucoma primário de ângulo aberto e hipertensão ocular. No grupo com hipertensão ocular, não foram observadas associações entre histerese da córnea e o fator de resistência corneana com os valores e os parâmetros estruturais e funcionais. No grupo com glaucoma primário de ângulo aberto foram observadas correlações positivas entre os valores de histerese corneana e a espessura a camada de fibras nervosas da retina (p<0,01, r=0,27), espessura média da camada de fibras nervosas da retina (p<0,01, r=0,33) e desvio médio (p<0,01, r=0,26), e correlações negativas entre o os valores do fator de resistência da córnea e a área de escavação (p<0,01, r=-0,39), a relação escavação/disco (p=0,02, r=-0,28), a relação copo-para-disco linear (p=0,02, r=-0,28) e a forma da escavação (p=0,03, r=-0,26). No grupo controle, correlações foram detectadas entre a histerese da córnea e área de escavação (p=0,03, r=0,19), relação escavação/disco (p=0,01, r=0,21) e relação copo-para-disco linear (p=0,01, r=0,22). Conclusões: Correlações distintas foram identificadas entre histerese da córnea e os valores de resistência da córnea e os parâmetros funcionais e estruturais nos grupos de glaucoma primário de ângulo aberto e controle. A histerese da córnea e o fator de resistência da córnea podem ter diferentes papéis na fisiopatologia do glaucoma.

Ocular abnormalities in morbid obesity / Anormalidades oculares na obesidade mórbida

ABSTRACT Purpose: Obesity is associated with eye diseases, but the underlying structural changes and pathogenic mechanisms have not been examined in detail. Here, we assessed the effects of morbid obesity on the morphometric indices of eye disease. Methods: Morbidly obese volunteers (n=101, body mass index [BMI] ³40) and healthy individuals (n=95, BMI: 18.50-24.99) were examined by Goldman applanation tonometry, pachymetry, and spectral domain optical coherence tomography. Intraocular pressure, anterior chamber depth, axial length, central corneal thickness, retinal nerve fiber layer thickness, central foveal thickness, and choroidal thickness were compared between groups. Results: Uncorrected intraocular pressure was significantly greater in the morbidly obese group than in the healthy control group (15.5 ± 2.5 vs. 14.5 ± 2.6 mmHg, p=0.009), whereas axial length, anterior chamber depth, and central corneal thickness did not differ between the groups. The mean retinal nerve fiber layer thickness at the temporal quadrant was reduced in the morbidly obese group (72.7 ± 13.6 vs. 85.05 ± 52.6 mm, p=0.024). Similarly, the mean retinal thicknesses at nasal and temporal 1500-mm locations were lower in the morbidly obese group (346.6 ± 18.2 vs. 353.7 ± 18.8 mm, p=0.008; 323.1 ± 20.3 vs. 330.0 ± 18.9 mm, p=0.001). The mean choroidal thickness was also reduced in almost all measurement locations (fovea, temporal 500 and 1000 mm, and nasal 500, 1000, and 1500 mm) of the obese group (p<0.05). Weight and BMI were negatively correlated with subfoveal choroidal thickness (r=-0.186, p=0.009; r=-0.173, p=0.015). Conclusion: Morbid obesity is associated with elevated uncorrected intraocular pressure and signs of neuropathy and retinopathy. Obesity may thus increase the risks of glaucoma and glaucomatous optic neuropathy.

RESUMO Objetivo: A obesidade está associada a doenças oulares, mas as mudanças estruturais subjacentes e os mecanismos patogênicos não foram examinados detalhadamente. Aqui avaliamos os efeitos da obesidade mórbida nos índices morfométricos da doença ocular. Métodos: Voluntários obesos mórbidos (n=101, índice de massa corporal ³40) e indivíduos saudáveis (n=95, índice de massa corporal 18,50 a 24,99) foram examinados por tonometria de aplanação de Goldman, paquimetria e tomografia de coerência óptica de domício espectral. A pressão intraocular, profundidade da câmara anterior, comprimento axial, espessura central da córnea, espessura da camada de fibras nervosas da retina, espessura foveal central e espessura da coroide foram comparadas entre os grupos. Resultados: A pressão intraocular não corrigida foi significativamente maior no grupo com obesidade mórbida do que no grupo controle saudável (15,5 ± 2,5 vs. 14,5 ± 2,6 mmHg, p=0,009), enquanto que o comprimento axial, profundidade da câmara anterior e espessura central da córnea não diferiram entre os grupos. A espessura média da camada de fibras nervosas da retina no quadrante temporal foi reduzida no grupo com obesidade mórbida (72,7 ± 13,6 vs. 85,05 ± 52,6 mm, p=0,024). Da mesma forma, a média das espesuras da retinianas nas localizações nasal e temporal de 1500 m foi menor no grupo com obesidade mórbida (346,6 ± 18,2 mm vs. 353,7 ± 18,8 mm, p=0,008; 323,1 ± 20,3 mm vs. 330,0 ± 18,9 mm, p=0,001). A espessura média da coroide também foi reduzida em quase todos os locais de mensuração (fóvea, temporal 500 e 1000 mm, nasal 500, 1000 e 1500 mm) do grupo obeso (p<0,05). Peso e índice de massa corporal foram negativamente correlacionados com a espessura da coroide subfoveal (r=-0,186, p=0,009; r=-0,173, p=0,015). Conclusão: A obesidade mórbida está associada à elevada pressão intraocular não corrigida e a sinais de neuropatia e retinopatia. A obesidade pode, assim, aumentar os riscos de glaucoma e neuropatia óptica glaucomatosa.

Comparison of the thinnest corneal thickness measured by Sirius, Oculyzer, AS-OCT and A-mode ultrasonography in myopic patients / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To compare the difference, correlation and consistency of the thinnest corneal thickness(TCT)in myopic patients among Sirius, Oculyzer, anterior segment optical coherence tomography(AS-OCT)and A-mode ultrasound pachymetry, in order to provide a reference for clinical applications.<p>METHODS: TCT was measured in 81 patients(162 eyes)treated between March and April, 2016 using Sirius, Oculyzer, AS-OCT and A-mode ultrasound pachymetry before femtosecond LASIK, and then the values were statistically analyzed.<p>RESULTS: TCT measured by A-mode ultrasound pachymetry, Sirius, Oculyzerand AS-OCT were respectively(537.91±24.12)μm,(538.12±22.64)μm,(538.20±23.74)μm,(527.04±23.11)μm(<i>P</i><0.01). There was a significant difference in TCT measurements among the four measurements. The results of AS-OCT were significantly smaller than those of the other three methods. There was no statistical difference among A-mode ultrasound pachymetry, Sirius and Oculyzer.Pearson correlation coefficient of measured value by the four measurements were more than 0.9(<i>r</i>=0.920, 0.914, 0.951, 0.908, 0.929, 0.919, <i>P</i><0.001), which means there were highly correlation between each other. The 95% <i>CI</i> of the consistency interval of A-mode ultrasound pachymetry and Sirius, A-mode ultrasound pachymetry and Oculyzer, A-mode ultrasound pachymetry and AS-OCT were(-18.77-18.33)μm,(-19.79-19.19)μm,(-3.79-25.53)μm, respectively. The Bland-Altman Plots demonstrates relatively good consistency between A-mode ultrasound pachymetry and the other three methods.<p>CONCLUSION:The TCT measured by AS-OCT were thinner than that measured by A-mode ultrasound pachymetry. There were a high correlation and consistency of the thinnest corneal thickness in myopic patients among Sirius, Oculyzer, AS-OCT and A-mode ultrasound pachymetry. The TCT measured by the four measurements can be referenced but not replaced since the 95% of the consistency intervals were wide.

Comparison of Central Corneal Thickness Measurements between Noncontact Specular Microscopy and Ultrasound Pachymetry

PURPOSE: We compared and analyzed central corneal thickness (CCT) measurements according to the corneal thickness obtained with noncontact specular microscopy (NCSM) and ultrasound pachymetry (USP). METHODS: CCT was measured in the order of NCSM and USP by a single optometrist in 120 eyes of 120 healthy subjects. The measurements were compared between the devices and the measurement agreements and correlations between the devices were analyzed. To determine if the measurements differed depending on the thickness of the cornea, the patients were divided into three tertile groups from the thinnest patient by CCT measurement using USP, and then the differences in CCT measured by the two devices were analyzed. RESULTS: The CCT measurements using NCSM and USP were 548.25 ± 4.64 µm and 533.09 ± 35.96 µm, respectively. NCSM measurements were found to be thicker, showing statistically significant differences between the measurements (p < 0.001). The two examinations showed a high degree of correlation (r = 0.878; p < 0.01). In the three groups, the differences in CCT measurements between NCSM and USP were 12.93 ± 21.88 µm, 16.85 ± 15.89 µm, and 15.70 ± 20.46 µm, respectively, but the differences between the three groups were not statistically significant (p = 0.655). CONCLUSIONS: Our results show that although the differences in CCT measurements using NCSM and USP were consistent regardless of the corneal thickness, the CCT measurements by NCSM and USP were highly correlated.

Comparison of intraocular pressure measurements between Icare PRO Tonometer, Goldmann Applanation Tonometer and non-contact tonometer in healthy and glaucomatous eyes / Comparação da medição da pressão intraocular entre o tonômetro Icare PRO, o tonômetro de aplanação de Goldmann e o tonômetro de não-contacto em olhos saudáveis e olhos glaucomatosos

Abstract Purpose: To validate the comparative measurements of intraocular pressure performed with IcarePRO tonometer (IPT) in relation to Goldmann applanation tonometer (GAT) and non-contact tonometer (NCT), as well as to evaluate the influence of central corneal thickness (CCT) on these values. Methods: This was a prospective and comparative study conducted during 6 months in the Department of Ophthalmology, Hospital de Braga, Portugal. The study population comprised two groups: healthy adults and adults with primary open angle glaucoma (POAG). The IOP values were obtained by the three tonometers and the order of execution was randomly selected. CCT values were obtained by ultrasonic pachymetry. Results: A total of 168 eyes (74 with diagnosis of POAG and 94 healthy) of 84 patients were included in this study. The mean IOP values obtained by IPT, GAT and NCT were 17.36±3.78 mmHg; 14.59±3.32 mmHg; and 17.04±4.01 mmHg, respectively. The comparison between IPT and NCT did not reveal statistically significant differences in the two groups studied. However, statistically significant differences were obtained between IPT and GAT values (p <0.001). The IOP values, recorded by all the tonometers, were significantly and positivily correlated with the CCT (p <0.001). Conclusion: IOP readings measured by IPT are comparable with those obtained by NCT, but higher than those obtained by the GAT. CCT values are correlated with IOP measurements with IPT, as it does in GAT and NCT, and should be always taken into consideration.

Resumo Objetivo: Validar os valores de pressão intraocular (IOP) realizados com o tonômetro IcarePRO (IPT) em relação ao tonômetro de aplanação de Goldmann (GAT) e tonômetro de sopro (NCP), assim como avaliar a influência da espessura central da córnea (CCT) nesses valores. Métodos: Estudo prospectivo e comparativo realizado durante 6 meses consecutivos no Departamento de Oftalmologia do Hospital de Braga, Portugal. A população estudada compreendeu dois grupos: adultos saudáveis e adultos com glaucoma primário de ângulo aberto (POAG). Os valores de IOP foram obtidos pelos três tonômetros e a ordem de execução foi selecionada aleatoriamente. Os valores de CCT foram obtidos por paquimetria ultrassônica. Resultados: Um total de 168 olhos (74 com diagnóstico de POAG e 94 saudáveis) de 84 pacientes foram incluídos neste estudo. Os valores médios de IOP obtidos pelo IPT, GAT e NCT foram de 17.36±3.78 mmHg; 14.59±3.32 mmHg; e 17.04±4.01 mmHg, respectivamente. A comparação entre IPT e NCT não revelou as diferenças estatisticamente significativas nos dois grupos estudados. No entanto, foram obtidas diferenças estatisticamente significativas entre os valores registados pelo IPT em comparação ao GAT (p <0.001). Os valores de IOP, medidos por todos os tonômetros, foram significativamente correlacionados com a CCT (p <0.001). Conclusão: As leituras de PIO medidas pelo IPT são comparáveis às obtidas pelo NCT, mas superiores às obtidas pelo GAT. Os valores de CCT estão correlacionados com medidas de IOP, tal como acontece com o GAT e NCT, pelo que devem ser levados em considerados.

Corneoscleral contact lenses fitting on irregular corneas after laser-assisted in situ keratomileusis / Lentes de contato corneoesclerais adaptadas em córneas irregulares após cirurgia LASIK

ABSTRACT Purpose: We aimed to describe the outcomes of corneoscleral contact lens fitting with multi-aspherical geometry designs in patients with irregular corneas after laser-assisted in situ keratomileusis (LASIK). Methods: This was a retrospective series of 18 patients (age, 26-38 years) selected from an eye clinic database. Participants were required to have unsatisfactory visual acuity with their current contact lenses or spectacles after LASIK for myopia correction. All patients were fitted with corneoscleral contact lenses designed to correct corneal surface irregularities. A diagnostic trial set was used for fitting, and assessments were performed according to a standardized methodology. Subjective comfort, visual acuity, central corneal thickness, endothelial cell count, and corneal-compensated intraocular pressure were evaluated. The follow-up period was one year. Results: Contact lens use was discontinued in 3 patients, thus leaving 24 eyes from 8 females and 7 males for analysis. The fitting characteristics were optimal in terms of lens position and movement. Statistically significant improvements were found in the best spectacle-corrected vision from before fitting to the visual acuity after fitting (p<0.001). Moreover, the patients reported high subjective comfort ratings and usage times (12.98 ± 2.3 hours/day). After one year of wear, visual acuity, subjective comfort, and usage time were maintained. No statistically significant adverse changes developed in the corneas over this period. Conclusion: Corneoscleral contact lenses with a multi-aspherical geometry design provide optimal visual acuity, improved comfort, and prolonged usage times in patients with irregular corneas after LASIK.

RESUMO Objetivo: Descrever os resultados do ajuste de lentes de contato corneoesclerais com geometria multiasférica em pacientes com córneas irregulares após cirurgia de ceratomileuse in situ assistida por laser (LASIK). Métodos: Esta foi uma série retrospectiva de 18 pacientes (idade, 26-38 anos) selecionados a partir de um banco de dados de uma clínica oftalmológica. Os participantes foram escolhidos ao manifestaram acuidade visual insatisfatória com suas lentes de contato ou óculos atuais depois de terem sido submetidos à LASIK para correção de miopia. Todos os pacientes receberam lentes de contato corneoesclerais projetadas para corrigir irregularidades na superficie da córnea. Um conjunto diagnóstico de prova foi usado para a adaptação e as avaliações foram feitas de acordo com uma metodologia padronizada. O conforto subjetivo, a acuidade visual, a espessura central da córnea, a contagem de células endoteliais e a pressão intraocular compensada da córnea foram avaliados. O período de acompanhamento foi de um ano. Resultados: O uso de lentes de contato foi descontinuado em 3 pacientes, deixando 24 olhos de 8 mulheres e 7 homens para análise. As características de adaptação foram ótimas em termos de posição e movimento da lente. Melhorias estatisticamente significativas foram encontradas na melhoria da visão corrigida por óculos antes de se ajustar a acuidade visual após a adaptação (p<0,001). Além disso, os pacientes relataram altos índices subjetivos de conforto e tempo de uso (12,98 ± 2,3 horas/dia). Após um ano de uso, a acuidade visual, o conforto subjetivo e o tempo de uso foram mantidos. Não houve alterações adversas estatisti­camente significativas nas córneas ao longo deste período. Conclusão: As lentes de contato corneoesclerais com projeto geométrico multiasférico proporcionam acuidade visual ideal, maior conforto e tempo de uso prolongado em pacientes com córneas irregulares após o LASIK.

Degeneração marginal pelúcida superior / Superior marginal pellucid degeneration

Resumo A degeneração marginal pelúcida (DMP) é uma ectasia corneana rara. Caracteriza-se por afinamento periférico, sem sinais inflamatórios, tipicamente inferior e bilateral, separado do limbo por área de espessura normal. Há protrusão da córnea acima da área de afinamento, resultando em elevado astigmatismo irregular. À topografia corneana, obtém-se a imagem característica, porém não patognomônica, em "asa de borboleta". Relata-se, nesse caso, um paciente com DMP superior - apresentação atípica da doença -destacando a importância da inclusão da DMP como hipótese diagnóstica nos casos de afinamentos corneanos periféricos não inflamatórios, que não comprometam apenas a região inferior da córnea.

Abstract Pellucid marginal corneal degeneration (PMCD) is a rare bilateral noninflammatory ectatic peripheral corneal disorder, usually involving the inferior portion of the cornea, separated from limbus by an area of normal corneal thickness. There is protrusion of the cornea above the thinning area, resulting in high irregular astigmatism. Corneal Topography shows the characteristic, but not pathognomonic, image of a "butterfly wing". A patient with superior PMCD - an atypical presentation of the disease - is presented, highlighting the importance of the inclusion of PMCD as a diagnostic hypothesis, in cases of non-inflammatory peripheral corneal thinning that does not compromise only the inferior corneal area.

Comportamento da pressão intraocular no tonômetro de aplanação de Goldman e pneumático durante o teste de sobrecarga hídrica / Intraocular pressure behavior in the Goldmann and pneumatic tonometer during water drinking test

Resumo Objetivo: Avaliar a concordância entre os tonômetros de aplanação de Goldman e pneumático na realização do teste de sobrecarga hídrica (TSH). Métodos: Estudo descritivo transversal composto por uma amostra de 102 olhos proveniente de um hospital particular em Goiânia (GO) entre 2013 a 2016, com avaliação das diferentes pressões intraoculares (PIO) nos tonômetros de aplanação de Goldman e pneumático quando submetidos ao TSH. Resultados: A média de idade foi de 52,17 (± 15,21) anos, sendo que60,8% dos pacientes pertenciam ao sexo feminino e 39,2% ao masculino. A média da espessura da córnea foi de 531,9(± 72,75) micra. Por regressão linear as variaveis idade e espessura da cornea central não ocorreram significancia estatistica entre os dois dispositivos analisados. Conclusão: Observou-se boa concordância nas medições entre os aparelhos de aplanação e o pneumático durante o teste de sobrecarga hídrica, porém necessita-se de novos estudos de maior impacto epidemiológico para confirmação desta assertiva.

Abstract Objective: To evaluate the consonance betweenthe Goldman and pneumática planation to nometers under the effect of the water drink test. Methods: Cross-sectional descriptive study consisting of a sample of 102 eyes from a private hospital in Goiânia (GO) from 2013 to 2015,with na evaluation of different intraocular pressures (IOP) in the Goldman and pneumatic flattening to nometers when submitted to TSH. Results: The average age was 52.17 (± 15.21) years old, 60.8% of the patients were female and 39.2% were male.The mean corneal thickness was 531.9(± 72.75) By linear regression the variables age and corneal thickness did not occur statistical significance between the two devices analyzed. Conclusion: Good agreement was observed in the measurements between the applanation devices and the tire during the water drink test, but new studies with a greater epidemiological impact were required to confirm this assertion.

Comparison of central corneal thickness measurements by PachPen ultrasonic pachymetry and the other two optical measuring instruments / 国际眼科杂志(Guoji Yanke Zazhi)

·AIM:To compare the similarities and differences of central corneal thickness (CCT) measured by different devices, so as to provide a safe, effective, simple and accurate method for measuring corneal thickness. ·METHODS: Totally 95 eyes of 95 cataract patients enrolled continuously for preoperative examination in ophthalmology department of Putuo Hospital Affiliated to Shanghai University of Traditional Chinese Medicine from September 2016 to December 2016. Handheld automatic PachPen ultrasonic pachymetry (USP), anterior segment optical coherence tomography (AS-OCT) and specular microscopy were respectively used to measure the central corneal thickness,and intraocular pressure was measured at the same time. The similarities and differences of these three different devices to measure the central corneal thickness and their correlations with intraocular pressure were observed. Then the data were analyzed statistically. · RESULTS: The CCT value measured by PachPen ultrasonic pachymetry was 544. 43 ± 36. 61μ m, the CCT value measured by AS-OCT was 527.09 ± 35.54μ m, and the CCT value measured by specular microscopy was 533.20 ± 30. 17μ m. There was significant difference between these three groups(F=6.272,P=0.002),and the CCT value measured by PachPen ultrasonic pachymetry was significantly higher than the other two groups. The correlation coefficients between the CCT values of these three groups and intraocular pressure were 0.290, 0.277 and 0.204 (P<0.05) respectively, of which the correlation between the CCT measured by PachPen ultrasonic pachymetry and the intraocular pressure was the highest. There was statistically significant correlation between the CCT values measured by these three measurements (P<0.001). ·CONCLUSION: The CCT value measured by PachPen ultrasonic pachymetry is the highest. The second CCT value is measured by specular microscopy, and the smallest CCT value is measured by AS-OCT. Obvious correlation and good consistency were found in the CCT values measured by three types of devices, and the CCT values were all correlated with intraocular pressure. Therefore,we should take more attention in clinic.

Corneal properties and glaucoma: a review of the literature and meta-analysis / Propriedades da córnea e glaucoma: revisão da literatura e meta-análise

ABSTRACT Purpose: Studies have suggested that corneal biomechanical properties influence intraocular pressure (IOP) measurements, namely central corneal thickness (CCT) and corneal hysteresis (CH). The present study aimed to investigate the associations of CH and CCT with glaucoma development. Methods: We performed a review of the literature and meta-analysis of observational studies (2006-2016) that included both adult glaucoma patients and controls and reported CCT and CH as outcomes. Nineteen studies were conside red eligible, and the mean difference (MD) between groups (patient and control) for both variables was used for statistical analyses. Results: A total of 1,213 glaucoma and 1,055 healthy eyes were studied. Quan titative analysis suggested that CH was significantly lower in the glaucoma group than in the control group (MD=-1.54 mmHg, 95% CI [-1.68, -1.41], P<0.0001). Additionally, CCT was significantly lower in the glaucoma group than in the control group (MD=-8.49 µm, 95% CI [-11.36, -5.62], P<0.001). Conclusion: Corneal properties appear to differ between glaucoma patients and healthy controls. Our results emphasize the importance of corneal biomechanical properties in IOP interpretation and should support further studies on the influence of CH and CCT in glaucoma screening and diagnosis.

RESUMO Objetivo: A literatura sugere que as propriedades biomecânicas da córnea, nomeadamente a espessura central da córnea (ECC) e a histerese corneana (HC), influenciam a medição da pressão intraocular (PIO). Este estudo teve como objetivo investigar a associação entre a ECC e a HC e o desenvolvimento de glaucoma. Métodos: Revisão da literatura e meta-análise. Foram incluídos estudos observacionais, publicados entre 2006 e 2016, que integrassem um grupo controle e um grupo de pacientes com glaucoma em que estes dois grupos apresentassem, igualmente, a ECC e a HC como parâmetros. Dezenove estudos foram considerados elegíveis e a diferença média (MD) daqueles parâmetros nos dois grupos foi utilizada para análise estatística. Resultados: Estudaram-se um total de 1.213 olhos com glaucoma e 1.055 olhos saudáveis. A análise quantitativa revelou que a HC é significativamente mais baixa no grupo de doentes com glaucoma quando comparada com o grupo controle (MD=-1,54 mmHg, intervalo de confiança de 95% [-1,68-1,41], P<0,00001). A ECC foi, também, significativamente mais baixa no grupo glaucoma quando comparada com os indivíduos saudáveis MD=-8,49 µm, intervalo de confiança de 95% [-11,36, -5,62], P<0,001). Conclusão: Os pacientes com glaucoma parecem possuir propriedades corneanas diferentes das que apresentam os indivíduos saudáveis. Os resultados enfatizam a importância das propriedades biomecânicas da córnea na interpretação da PIO e devem contribuir para novos estudos sobre a influência da HC e da ECC no rastreio e diagnóstico do glaucoma.

Comparison of Central Corneal Thickness Measured by Swept-source Optical Coherence Tomography and Ultrasound Pachymetry

PURPOSE: To analyze and compare ultrasound pachymetry (USP) with a more recently adopted device, the intra ocular lens (IOL) master 700, which are both used to measure central corneal thickness. METHODS: The central corneal thickness was measured in 24 eyes of 12 glaucoma patients and in 83 eyes of 42 normal patients. First, the IOL master 700 was used to measure the central corneal thickness, followed by measurements taken using USP later. The results were analyzed using a paired t-test. We analyzed the agreement and the correlations between the two test devices by using Bland-Altman plots and the Pearson correlation test. To evaluate the reproducibility, measurements with the IOL master 700 were taken twice for a few normal patients within a small time interval. RESULTS: Via the IOL master 700, the thickness of the central cornea showed a high reproducibility and repeatability, demonstrating 2.7 ± 1.7 µm for the test-retest variability, 6.78% for the coefficient of variation, and 0.997 for the intraclass correlation value. The mean measurements using USP and the IOL master 700 are 554.4 ± 37.4 µm and 551.1 ± 37.1 µm, respectively, showing that the IOL master 700 measured significantly smaller values than USP with a p-value < 0.001. The deviations between the two methods are scattered throughout the 95% confidence interval. According to the Pearson correlation test, the measured values of the two test devices were found to have a highly positive correlation (r = 0.977, p < 0.0001). CONCLUSIONS: This study demonstrated that the central corneal thickness (CCT) measured via the IOL master was significantly thinner than that of USP, and the two test devices had a high correlation and good agreement. The CCT value measured via the IOL master 700 also exhibited high reproducibility.

Validity of Tono-pachymetry for Measuring Corrected Intraocular Pressure in Non-surgical and Post-photorefractive Keratectomy Eyes

PURPOSE: To assess the validity of central corneal thickness (CCT) and corrected intraocular pressure (IOP) values obtained by tono-pachymetry in non-surgical and post-photorefractive keratectomy (PRK) eyes. METHODS: For the study, 108 young healthy participants and 108 patients who had PRK were enrolled. Measurements were randomly performed by tono-pachymetry, ultrasonic (US) pachymetry, and Goldmann applanation tonometry (GAT). CCT measurement by tono-pachymetry was compared to that of US pachymetry. The corrected IOP value obtained by tono-pachymetry was compared to that obtained by US pachymetry and GAT. The corrected IOP from US pachymetry and GAT was calculated using the identical compensation formula built into the tono-pachymetry. Bland-Altman plot and paired t-test were conducted to evaluate the between-method agreements. RESULTS: The mean CCT measurement using tono-pachymetry was significantly greater by 7.3 µm in non-surgical eyes (p < 0.001) and 17.8 µm in post-PRK eyes (p < 0.001) compared with US pachymetry. Differences were significant in both Bland-Altman plotand paired t-test. The mean difference of corrected IOP values obtained by tono-pachymetry and calculated from measurements by US pachymetry and GAT was 0.33 ± 0.87 mmHg in non-surgical eyes and 0.57 ± 1.08 mmHg in post-PRK eyes. The differences in the Bland-Altman plot were not significant. CONCLUSIONS: The CCT measurement determined using tono-pachymetrywas significantly thicker than that of US pachymetry. The difference in CCT was greater in post-PRK eyes than in non-surgical eyes. However, the corrected IOP value obtained by tono-pachymetry showed reasonable agreement with that calculated from US pachymetry and GAT measurements.

Comparison of central corneal thickness estimated by an ultrasonic pachymeter and non-contact specular microscopy / Comparação da espessura central de córnea estimada por um paquímetro ultrassônico e por um microscópio especular sem contato

ABSTRACT Purpose: To compare central corneal thickness (CCT) measurements of healthy individuals obtained with ultrasonic pachymetry (UP) and non-contact specular microscopy (NCSM). Method: In total, 148 eyes of 74 subjects with no ocular or systemic diseases were included in the study. Central corneal thickness measurements of all patients performed with UP and NCCM were compared. Results: A total of 74 subjects (38 females) were included in this study. The mean age was 45.2 ± 18.4 (range 12-85) years. The mean central corneal thickness of all 148 eyes was 546.9 ± 40 μm with UP and 510.8 ± 42 μm with NCSM. The mean central corneal thickness measured with NCSM was 35 μm thinner than that measured with UP (p<0.001). A high degree of agreement was found between the two methods (r=0.942, p<0.001). Conclusions: Our results suggest that NCSM measures thinner corneas than UP and that the correction formula we identified should be applied when comparing between these two devices.

RESUMO Objetivo: Comparar as medidas de espessura central corneana (CCT) de indivíduos saudáveis obtidos pela paquimetria ultrassônica (UP) e microscopia especular sem contato (NCSM). Método: Cento e quarenta e oito olhos de 74 indivíduos que não tinham doenças oculares ou sistêmicas foram incluídos no estudo. Medidas da espessura central corneana de todos os pacientes foram comparadas entre UP (SP 100, Tomey, Nagoya, Japão) e do NCSM (NSP-9900, Konan Medical, Inc., Hyogo, Japão). Resultados: Um total de 74 indivíduos (38 mulheres) foram incluídos neste estudo. A idade média foi de 45,2 ± 18,4 (variação 12-85) anos. A medida média da espessura central corneana de todos os 148 olhos foi 546,9 ± 40 μm com UP e 510,8 ± 42 μm com NCSM. A espessura central corneana média avaliada pelo NCSM foi de 35 μm mais fina do que a UP (p<0,001). Foi encontrado um elevado grau de concordância entre os dois métodos (r=0,942, p<0,001). Conclusões: Nossos resultados sugerem que a microscopia especular sem contato mede córneas mais finas em comparação com a UP e que o fator de correção identificado deve ser aplicado ao fazer comparações entre esses dois aparelhos.

Accuracy of Corvis ST for the measurement of central corneal thickness and intraocular pressure in myopia / 中华实验眼科杂志

Background Corvis ST corneal biomechanical analyzer (Corvis ST) can offer corneal biomechanical parameters,intraocular pressure (IOP) and central corneal thickness (CCT),and measured IOP value was corrected based on CCT and biomechanical factors.Corvis ST is applied abroad,but the study on its accuracy is few in China.Objective This diagnostic trial was to evaluate the accuracy of Corvis ST for CCT and IOP measurement in myopic population.Methods Fifty-six eyes from 56 myopic patients were prospective recruited in Visual Science and Optometry Center of Guangxi from November to December in 2012.IOP was measured by using Corvis ST and Goldmann applanation tonometer (GAT),and CCT was measured by Corvis ST and A type ultrasonic pachymetry.The CCT difference between Corvis ST and A type ultrasonic pachymetry as well as IOP between Corvis ST and GAT were compared by using paired-t test,and agreements of measured outcomes were analyzed by Bland-Altman method.This study was approved by the Ethic Committee of People's Hospital of Guangxi and written informed consent was obtained from all subjects.Results The CCT from Corvis ST was (539.82± 19.79) μm,which was significantly higher than (535.34± 19.41) μm from A type ultrasonic pachymetry (t =4.19,P＜0.001).Bland-Altman analysis revealed that the CCT measured by Corvis ST was 4.5 μm higher than that of A type ultrasonic pachymetry,with the 95％ limit of agreement ranged from-11.2 to 20.2 μm,and 7.1％ (4/56) of points were located at the outside of the 95％ confidence interval.The IOP measured by Corvis ST and GAT were (15.75±1.60) mmHg and (16.23 ±2.40) mmHg,respectively,showing statistically significant difference between the two methods (t=2.15,P =0.04).Bland-Altman analysis revealed that the IOP measurement of Corvis ST was 0.5 mmHg lower than that of GAT,with the 95％ limit of agreement ranged from-3.8 to 2.8 mmHg,and 3.57％ (2/56) of points were located at the outside of the 95％ confidence interval.Conclusions CCT obtained by Corvis ST is higher than that by A type ultrasonic pachymetry with poor agreement between these two outcomes,and the two methods cannot replace each other clinically in myopic eyes.IOP value from Corvis ST is slightly lower than that from GAT,showing a good agreement between these two outcomes.The IOP value of Corvis ST shows satisfactory accuracy.