Corneal ectasia following photorefractive keratectomy: a confocal microscopic case report and literature review / Ectasia corneana após ceratectomia fotorrefrativa: relato de caso de microscopia confocal e revisão da literatura

ABSTRACT The occurrence of corneal ectasia after photorefractive keratectomy is a rare but serious complication of refractive surgery. Possible risk factors are not well assessed, but a probable reason is the failure to detect keratoconus preoperatively. In this report, we describe a case of corneal ectasia after photorefractive keratectomy in a patient who presented a suspicious tomography pattern preoperatively but had no degenerative alterations associated with pathologic keratoconus, as revealed by in vivo corneal confocal microscopy. We also review eligible case reports of post-photorefractive keratectomy ectasia to find similar characteristics.

RESUMO A ocorrência de ectasia corneana após ceratectomia fotorrefrativa é uma complicação rara, porém grave, em cirurgia refrativa. Os possíveis fatores de risco não são bem avaliados, mas a opinião atual é que a falha na detecção de ceratocone pré-operatório possa ser o principal motivo. Neste relato, descrevemos um caso de ectasia corneana após ceratectomia fotorrefrativa em paciente apresentando padrão tomográfico suspeito no pré-operatório, mas sem alterações degenerativas associadas a ceratocone patológico, conforme revelado por microscopia confocal in vivo da córnea. Além disso, revisamos, na literatura, relatos de casos elegíveis de ectasia pós-ceratectomia fotorrefrativa para encontrar características semelhantes.

Femtosecond laser-assisted laser in situ keratomileusis for the correction of high myopia in Meesmann corneal dystrophy: a case report / Femto-LASIK para correção de alta miopia na distrofa corneana de Meesmann: relato de caso

ABSTRACT The patient was a 26-year-old woman who had manifest refraction and uncorrected and corrected distance visual acuities of -7.00 × -4.50 at 175°, 20/400, and 20/25, respectively, in the right eye, and -3.25 × -5.25 at 179°, 20/200, and 20/25, respectively, in the left eye. In the right and left eyes, the mean corneal thicknesses were 733 and 749 µm, and the maximum epithelial thicknesses were 70 and 68 µm, respectively. Myriads of intraepithelial cysts were observed in the slit-lamp examination. At 30 months after femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK), the manifest refraction and uncorrected and corrected distance visual acuities were respectively 0.00 × -1.25 at 55°, 20/25, and 20/20 in right eye, and 0.00 × -0.50 at 135°, 20/20, and 20/20 in the left eye. In this case of Meesmann dystrophy, myopia was successfully treated with thick flap femto-LASIK without complications or ectasia.

RESUMO A paciente era uma mulher de 26 anos com refração manifesta, acuidade visual para longe não corrigida e corrigida de -7,00 × -4,50 a175°, 20/400 e 20/25 no olho direito e -3,25 × -5,25 a 179°, 20/200 e 20/25 no olho esquerdo. A espessura média da córnea foi de 733 e 749 µm, e a espessura epitelial máxima foi de 70 e 68 µm, respectivamente no olho direito e no esquerdo. Inúmeros cistos intraepiteliais foram observados no exame com lâmpada de fenda. Trinta meses após o femto-LASIK, a refração manifesta, a acuidade visual para longe não corrigida e corrigida eram respectivamente de 0,00 × -1,25 a 55°, 20/25 e 20/20 no olho direito e 0,00 × -0,50 a 135°, 20/20 e 20/20 no olho esquerdo. Neste caso de distrofia de Meesmann, a miopia foi tratada com sucesso com femto-LASIK de retalho espesso sem complicações ou ectasia.

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.

Biometry and intraocular power calculation using a swept-source optical coherence tomography: A repeatability and agreement study

Purpose: To evaluate the repeatability of biometry and intraocular lens (IOL) power using Galilei G6 and to determine the agreement of its measurements with those of IOL Master 700 and IOL Master 500. Methods: Hundred mature cataract eyes were examined twice with Galilei G6 and the results were compared with those of other two devices. Axial length (AL), minimum (K1), maximum (K2), and mean keratometry, anterior chamber depth (ACD), white-to-white (WTW) diameter, lens thickness (LT), and the calculated IOL power were the studied parameters. The correlation coefficient, within-subject standard deviation (Sw), Bland–Altman method, and 95% limits of agreement (LoA) were used for statistical analysis. Results: The intraclass correlation coefficient (ICC) was above 0.9 for all indices, and the LoA ranged from a minimum of 0.08 mm for AL to a maximum of 0.50 D for K1. Sw also ranged between a minimum of 0.02 for AL, ACD, and WTW and a maximum of 0.13 for K1. In the Galilei G6–IOL Master 700 pair, the narrowest and widest LoA were calculated for AL (0.07 mm) and K2 (0.49 D), respectively. In the Galilei G6–IOL Master 500 pair, the narrowest and widest widths of LoA were calculated for AL (0.17 mm) and K2 (0.92 D), respectively. In the first pair, the LoA of IOL power (0.57 D) were the best for Haigis formula and in the second pair, the best agreement (LoA: 0.35 D) was observed for Holladay-1. Conclusion: Galilei G6 provided repeatable biometric measurements. The agreement between biometry and IOL power calculation was better in the Galilei G6–IOL Master 700 pair compared to the Galilei G6–IOL Master 500

Mapping the corneal thickness and volume in patients with Down syndrome: a comparative population-based study / Mapeamento da espessura e do volume da córnea em pacientes com Síndrome de Down: estudo comparativo de base populacional

ABSTRACT Purpose: To measure the central-to-peripheral corneal thickness and its volume according to age and gender in 10-30-year-old patients with Down syndrome (DS) and in matched individuals without DS. Methods: In the report, 202 normal pattern right eyes of patients with Down syndrome and 190 right eyes of individuals without Down syndrome and compared averages using independent sample t-tests and multiple linear regression models. The measured variables included the apical corneal thickness; the minimum corneal thickness; the average thickness on rings at 2 mm (R2), 3 mm (R3), and 4 mm (R4); the corneal volume in the central zones at 2-, 3-, 4-, and 10-mm diameters; Ambrosio's relational thickness; and the pachymetric progression indices. Results: The mean age of the participants was 16.99 ± 4.70 and 17.22 ± 4.54 years (p=0.636). The means ± SD were 516.7 ± 33.0 and 555.7 ± 33.1 µm for apical corneal thicknesses, 508.0 ± 33.5 and 549.0 ± 40.6 µm for minimum corneal thicknesses, 543.0 ± and 588.4 ± 33.8 µm for R2s, 584.9 ± 35.6 and 637.0 ± µm for R3s, 646.9 ± 38.5 and 707.6 ± 37.1 µm for R4s, 396.4 ± 102.3 and 462.7 ± 96.2 µm for Ambrosio's relational thicknesses, 1.36 ± 0.37 and 1.22 ± 0.18 for pachymetric progression index maximums, 1.62 ± 0.11 and 1.74 ± 0.11 mm3 for corneal volume at 2 mm, 3.73 ± 0.24 and 4.01 ± 0.24 mm3 for corneal volume at 3 mm, 6.76 ± 0.44 and 7.30 ± 0.43 mm3 for corneal volume at 4 mm, and 57.03 ± 3.44 and 61.51 ± 3.40 mm3 for total corneal volume in the Down syndrome and control groups, respectively (all p<0.001). All the above indices were inversely related to age, but not to gender. Ambrosio's relational thickness maximum and the pachymetric progression index maximum were independent of age and gender. Conclusion: Non-keratoconic patients with Down syndrome had thin corneas with a homogeneous distribution. Therefore, the reference ranges of cornea thickness and volume should be re-defined for this patient population.

RESUMO Objetivo: Medir a espessura corneana central e periférica e se4u volume de acordo com a idade e gênero em pacientes com idades entre 10 e 30 anos com síndrome de Down e em indivíduos saudáveis sem síndrome de Down. Métodos: No estudo 202 olhos normais direitos de pacientes com síndrome de Down e 190 olhos direitos de indivíduos sem síndrome de Down e médias comparadas usando o teste t de amostras independentes e modelos de regressão linear múltipla. As variáveis medidas incluíram a espessura da córnea apical, a espessura mínima da córnea, a espessura média dos anéis a 2 mm (R2), 3 mm (R3) e 4 mm (R4), o volume corneano nas zonas centrais nos diâmetros de de 2, 3, 4 e 10mm, a espessura relacional de Ambrosio e os índices de progressão paquimétrica. Resultados: A idade média dos participantes foi de 16,99 ± 4,70 e 17,22 ± 4,54 anos (p=0,636). As médias ± DP foram 516,7 ± 33,0 e 555,7 ± 33,1 µm nas espessuras da córnea apical, 508,0 ± 33,5 e 549,0 ± 40,6 µm para espessura mínima da córnea, 543,0 ± 33,9 e 588,4 ± 33,8 µm nos R2, 584,9 ± 35,6 e 637,0 ± 34,5 µm para R3, 646,9 ± 38,5 e 707,6 ± 37,1 µm para R4, 396,4 ± 102,3 e 462,7 ± 96,2 µm 0,18 para os índices máximos de progressão paquimétrico, 1,62 ± 0,11 mm3 e 1,74 ± 0,11 mm3 para o volume corneano a 2 mm, 3,73 ± 0,24 mm3 e 4,01 ± 0,24 mm3 para o volume corneano a 3 mm, 6,76 ± 0,44 mm3, 7,30 ± 0,43 mm3 para o volume corneano a 4 mm e 57,03 ± 3,44 mm3 e 61,51 ± 3,40 mm3 para o volume corneano total nos grupos com Síndrome de Down e controle, respectivamente (todos p<0,001). Todos os índices acima foram inversamente relacionados à idade mas não ao gênero. A espessura relacional de Ambrosio máxima e o índice de progressão paquimétrico máximo foram independentes da idade e do gênero. Conclusão: Os pacientes sem ceratocone com Síndrome de Down apresentaram córneas finas com distribuição homogênea. Portanto, os intervalos de referência da espessura e volume da córnea devem ser redefinidos para essa população de pacientes.

Living related conjunctival limbal allograft and amniotic membrane transplantation for limbal stem cell deficiency in chemically injured eyes / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To evaluate the clinical success of living related conjunctival limbal and amniotic membrane transplantation for treatment of chemical injury induced limbal stem cell deficiency.METHODS: From July 2005 to December 2007, 10 eyes of 9 male patients with chemical injury induced limbal stem cell deficiency were included in the study. All subjects underwent living related conjunctival limbal and amniotic membrane transplantation. Blepharorrhaphy was performed in two cases. Systemic immunosuppression with cyclosporine and prednisolone was initiated.RESULTS: Complete corneal epithelialization was observed in 3 eyes (30%). In one of the patients immunologic rejection and corneal melting led to perforation 1.5 months after surgery. The increasing dose of systemic immunosuppression was used to control it. Three eyes were described as primary failure because graft could not re-epithelialize the corneal surface. The remained four eyes showed partial re-epithelialization, but failed to cover the entire corneal surface with epithelium. Best corrected visual acuity ranged from hand movement to counting finger at 1 meter before the surgery and after the surgery was light perception to 20/80. Five eyes had visual improvement without any additional procedure. Dry eye and persistent inflammation were known as main causes of failure.CONCLUSION: Living related conjunctival limbal allograft and amniotic membrane transplantation can be a good option in the management of limbal stem cell deficiency in selected cases in which tear production and control of ocular inflammation are adequate.