Analysis of ocular biometric parameters in Tibetan patients with age-related cataract / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To compare the differences of ocular biometric parameters of age-related cataract between Tibetan and Han ethnic groups, and to analyze the distribution characteristics of ocular biometric parameters in Tibetan cataract patients.METHODS:Retrospective cohort study. A total of 661 patients(1 030 eyes)with age-related cataract confirmed in the hospital between January 2019 and December 2020 were enrolled. The parameters of axial length, anterior chamber depth, keratometry, corneal astigmatism and astigmatic axis were measured by IOL Master 500 in 483 cases(739 eyes)of Tibetan age-related cataract patients and 178 cases(291 eyes)of Han patients.RESULTS:The axial length, anterior chamber depth and corneal astigmatism of the Tibetan patients with age-related cataract were 23.33(22.81, 23.86)mm, 3.04(2.79, 3.30)mm and 0.73(0.47, 1.07)D. The mean keratometry was 43.89±1.35 D. The results indicated that Tibetan cataract patients had shorter axial lengths and smaller keratometry compared to Han patients(all P<0.05). Age in Tibetan patients was negatively correlated with axial length and anterior chamber depth, and positively correlated with keratometry(all P<0.05). Tibetan male patients had longer axial lengths, deeper anterior chambers, and flatter corneas compared to female patients(all P<0.05).CONCLUSION:There were differences in ocular biometric parameters between age-related cataract patients of Tibetan and Han ethnicities. The distribution of ocular biometric parameters in Tibetan cataract patients varied across different age groups and gender groups.

Estimation of surgically induced astigmatism after small-incision cataract surgery done by junior residents

Purpose: To estimate the postoperative astigmatism after small?incision cataract surgery (SICS) done by junior residents at the end of 1 and 3 months. Methods: This observational longitudinal study was conducted at the Department of Ophthalmology of a tertiary eye care hospital and research center. 50 patients enrolled in the study underwent manual small incision cataract surgery by junior residents. Preoperative detailed ocular examination was done, which included keratometric estimation using autokeratometer (GR?3300K). Incision length, distance of incision from the limbus, and type of suturing technique were noted. Postoperatively, keratometric readings were noted at 1 and 3 months. Astigmatism (surgically induced astigmatism [SIA]) was estimated using Hill’s SIA calculator version 2.0. All the analyses were performed using Statistical Package for the Social Sciences (SPSS) ver. 26.0 (IBM Corp., USA) software, and the statistical significance was tested at a 5% level. Results: Out of 50 patients, 54% had SIA between 1.5 and 2.5 D and 32% had SIA of more than 2.5 D. Only 14% had SIA less than 1.5 D at the end of 1 month. While 52% had SIA between 1.5 and 2.5 D, 22% had SIA between 1.5 and 2.5 D and 26% had SIA less than 1.5 D at the end of 3 months. Conclusion: The SIA in most of the SICS done by junior residents was above 1.5 D. It depended mainly on the incision length, its distance from the limbus, and the suturing technique.

Accelerated corneal collagen cross-linking in progressive keratoconus: Five-year results and predictors of visual and topographic outcomes

Purpose: To analyze the 5?year results of accelerated corneal collagen crosslinking (CXL) for progressive keratoconus and identify preoperative characteristics predictive of visual and topographic outcomes. Methods: A prospective interventional case series. Nineteen eyes of 19 patients receiving accelerated CXL with settings of 18 mW/cm2 for 5 min were included. Clinical and topographic parameters were assessed. Linear regression and logistic regression were used to compare the R2 and odds ratio (OR), respectively, between baseline characteristics and postoperative outcomes. Results: Corrected distance visual acuity (CDVA) remained stable from 0.28 ± 0.21 to 0.25 ± 0.18 logMAR (P = 0.486). The mean cylindrical refraction was stable (P = 0.119). The maximal keratometry (Kmax) decreased from 61.99 ± 10.37 to 59.25 ± 7.75 D (P < 0.001), flattening in the flattest and steepest meridians and mean keratometry were also observed (P ? 0.040). The mean anterior elevation at the apex reduced from 21.42 ± 16.69 to 18.53 ± 12.74 ?m (P = 0.013) and changes in posterior elevation were non?significant (P = 0.629). Preoperative Kmax best predicted the postoperative change in Kmax (R2 = 0.55, P < 0.001) compared to the other baseline characteristics (P ? 0.028), whereas preoperative CDVA was the only significant predictor of postoperative change in CDVA (R2 = 0.41, P = 0.003). Accelerated CXL is less likely to fail in eyes with a steeper preoperative Kmax (OR = 0.74, P = 0.040) or greater posterior elevation at the apex (OR = 0.91, P = 0.042). Conclusion: Kmax significantly decreased following accelerated CXL. Eyes with worse preoperative CDVA and higher Kmax were more likely to have an improvement in visual acuity and corneal flattening.

Knowledge, Attitude and Practices among Undergraduate Medical Students Regarding Surgical Correction of Refractive Errors; a Cross-sectional Study

Aim: This study was aimed to assess the knowledge, attitude and practices regarding refractive error correction surgeries among undergraduate medical students.Study Design: In this study cross-sectional study design was used.Duration and Place of Study: The study was conducted amongst the undergraduate MBBS students studying at Dow Medical College, Karachi. The duration of study was seven months (August, 2019 till February, 2020).Methods: A sample size of 189 was calculated for the study with confidence level 95% and confidence limit 5%. Data was collected through a validated self-administered questionnaire which was divided in five subsections used to gain information regarding participant抯 demographics, knowledge, attitude and practices regarding refractive error surgeries. Data was analyzed using IBM SPSS V.22.Results: In our study 189 students with a mean age of 21�8 years were included. Among the participants 112 (59.3%) had refractive errors. Glasses were used by majority 76 (67.9%) of participants for visual correction. Use of refractive error correction methods at all times was reported by 72 (66.7%) participants. Majority of respondents 142 (75.5%) had heard about surgery being used for correction of refractive errors. A large number of students 117 (66%) refused for surgery and fear of the outcomes was one of the reason for this refusal.Conclusion: We found that majority of the participants were aware about refractive error correction surgeries yet most of them showed unwillingness for these procedures. This negative attitude must be changed to positive in order to enhance the practice for these procedures.

A Study of Changes in Refractive Status Pre and Post Pterygium Surgery among Patients of Tertiary Care Hospital of Ahmedabad City

Background : Pterygium is a fibrovascular subconjunctival tissue also called Tenon’s Capsular growth occurring mostly in the palpebral fissure area from the nasal aspect towards the limbus over the Cornea and in this process the Corneal Pathology is changed especially the epithelium and bowman’s layer of the cornea are destroyed1. A major problem seen in most of postpterygium surgery is the complication of recurrence and it is usually seen in young patients with fleshy large pterygium1. This issue is addressed by Pterygium Surgery with either Conjunctival Autograft (CAG) or Amniotic Membrane Graft (AMG)1. Stem cells are present in limbal conjunctiva and in amniotic membrane, which provide a barrier between cornea and conjunctiva, preventing regrowth and also provide a smooth regular surface to the eyeball2. another reason and technique to prevent recurrence is by excising the pathological part of conjunctiva and resecting tenon’s capsule up to far periphery2. Aims and Objectives : The aim of the study is to investigate pre-operative and postoperative difference between the amount of astigmatism prior to the surgery and after the Pterygium Excision Surgery with either CAG or AMG. Materials and Method : A prospective cross-sectional study was undertaken of 26 cases, who underwent Pterygium Surgery under local anaesthesia with Conjunctival Autograft or Amniotic Membrane Graft for a period of one year in a Tertiary Healthcare Hospital. Pre-operative Best Corrected Visual Acuity, Anterior Segment Examination, Slit Lamp Examination, Dilated Retinoscopy and Fundus examination, Keratometry and Post mydriatic refraction was done. Then the patient underwent Pterygium Excision Surgery with Conjunctival Autograft or Amniotic Membrane Graft under local anaesthesia. All patients were re-examined 1 month after the surgery for final Refraction and Keratometry. Result : Among total of 26 patients, the comparison between pre- and postoperative values of Refraction and of Corneal Astigmatism was performed using z test. The pre-operative Mean for Astigmatism was 1.70 and SD was 0.43. The postoperative mean for Astigmatism was 0.57 and SD was 0.26. The pre-operative Keratometry mean was 2.73 and SD was 0.14. The Post operative Keratometry Mean was 1.50 and SD was 0.55. (p value, 0.0001) Conclusion: Pterygium is a lesion which also affects the ocular surface, thus leading to one of the causes for ocular surface abnormality. Pterygium surgeries results in elimination of the Pulling Factor and Corneal Curvature thus reducing or eliminating Astigmatism and thereby providing better visual restoration and cosmetic outcome

Analyze the effect of keratometry on the calculation accuracy of intraocular lens diopter in patients with normal axial cataract / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To evaluate the effect of keratometry on the calculation accuracy of intraocular lens(IOL)diopter in patients with normal axial cataract.METHODS:Totally 157 cases(157 eyes)with age related cataract were collected in Kaifeng Central Hospital from June 2020 to June 2021. Patients were divided into 3 groups according to keratometry: group A(53 eyes)(K<42D), group B(55 eyes)(42D≤K≤46D), group C(49 eyes)(K>46D). The IOL diopter was calculated by SRK/T, Hoffer Q, Holladay 2, Haigis, Kane and Barrett Ⅱ formulas respectively. Subjective optometry was performed after 1mo operation. The average refractive prediction error(RPE)and mean absolute error(MAE)were calculated, and their differences were compared and analyzed.RESULTS:There were significant difference between RPE of each formula and 0D in groups A and C(<i>P</i><0.05), and Barrett Ⅱ formula was significantly different with SRK/T, Hoffer Q, Holladay 2 and Haigis formula(<i>P</i><0.01), but was no significantly different with Kane formula in RPE(<i>P</i>>0.01). There was no significant difference in RPE between group B and 0D(<i>P</i>>0.05). The ratio of Barrett Ⅱ formula in MAE≤0.5D in group A was significantly higher than SRK/T, Hoffer Q, Holladay 2 and Haigis formula(all <i>P</i><0.01), but there was no significant difference compared with Kane formula(<i>P</i>>0.01). In group B, there was no significant difference among Barrett Ⅱ formula and the other formulas in the ratio of MAE≤0.5D and ≤1.0D(all <i>P</i> >0.01). In group C, the ratio of SRK/T and Hoff Q formula in MAE≤0.5D was lower than Barrett Ⅱ formula(all <i>P</i><0.01), and there were no significant difference among Barrett Ⅱ formula and the other formulas in the ratio of MAE≤1.0D(<i>P</i> >0.01).CONCLUSION:If K<42D or K>46D before operation, the commonly used formulas will produce refractive error, but the accuracy of Kane and Barrett Ⅱ formulas are still higher than other formulas.

Development of approaches to assess corneal astigmatism before cataract surgery / 国际眼科杂志(Guoji Yanke Zazhi)

With the rapidly improvement of people's living standard and diversification life style, obtaining better visual quality has become a new goal of cataract surgery. Corneal astigmatism directly affects the selection of functional intraocular lens(IOL)in cataract surgery and the recovery of postoperative visual function. The types of corneal astigmatism are no longer limited to a single astigmatism value, but subdivided into anterior corneal astigmatism, posterior corneal astigmatism, total corneal astigmatism and corneal higher order astigmatism. The corresponding examination equipment and technology are also updated. According to the characteristics and application of different equipment, clinicians can select appropriate examination equipments to evaluate the preoperative corneal astigmatism, so as to provide reference for formulating more accurate refractive cataract surgery planning. It is important for the axis and power calculation of Toric IOL and the selection of multifocal IOL. This paper reviews the recent progress of corneal astigmatism examination before cataract surgery.

Um estudo de correlação entre a contagem endotelial da córnea em pacientes com diferentes estágios de ceratocone usando a microscopia especular / A correlation study between a corneal endothelial count in patients with different stages of keratoconus using specular microscopy

RESUMO Objetivo: Avaliar a contagem endotelial da córnea em pacientes com ceratocone (KCN) por microscopia especular e correlacionar com o estágio do ceratocone. Métodos: Noventa e três olhos de 61 pacientes com KCN foram incluídos neste estudo transversal. Os olhos foram classificados nos estágios 1 a 4 de KCN de acordo com a classificação de Amsler-Krumeich utilizando ceratometria obtida pela topografia de córnea e leituras de paquimetria obtidas pela microscopia especular. Resultados: A idade variou de 12 a 43 anos, média ± (desvio padrão) 22,1 ± 6,7 anos. A ceratometria média variou de 42,25 a 71,4 D (53,0 ± 6,1 D). A paquimetria variou de 350 a 606 µm, (461,7 ± 47,1 µm). Em relação a classificação, 23 pacientes (24,7%) apresentavam estágio 1, 24 (25,8%) estágio 2, 5 (6,5%) estágio 3 e 41 pacientes (44,1%) estágio 4. Não foi observada correlação linear entre ceratometria média e contagem de células endoteliais (Coeficiente de correlação de Pearson = -0,05). Nos estágios iniciais a moderados de KCN, a média da contagem de células endoteliais foi 2738,3 ± 285,4 cel/mm2, enquanto no grupo de KCN avançado (estágios 3 e 4) foi 2670,6 ± 262,7 cel/mm2, p= 0,24. Conclusões: Não há correlação entre a contagem de células endoteliais e o estágio do KCN.

ABSTRACT Objective: To evaluate the corneal endothelial count in patients with keratoconus (KCN) by specular microscopy and correlate with the stage of keratoconus. Methods: Ninety-three eyes from 61 patients with KCN were included in this cross-sectional study. The eyes were classified into KCN stages 1 to 4 according to the Amsler-Krumeich classification using keratometry obtained by corneal topography and pachymetry readings obtained by specular microscopy. Results: Age ranged from 12 to 43 years, mean ± (standard deviation) 22.1 ± 6.7 years. The average keratometry ranged from 42.25 to 71.4 D, (53.0 ± 6.1 D). Pachymetry ranged from 350 to 606 µm, (461.7 ± 47.1 µm). Regarding the Amsler classification, 23 patients (24.7%) had stage 1, 24 (25.8%) stage 2, 5 (6.5%) stage 3 and 41 patients (44.1%) stage 4. No linear correlation was observed between mean keratometry and endothelial cell count (Pearson's correlation coefficient = -0.05). In the early to moderate stages of KCN, the mean endothelial cell count was 2738.3 ± 285.4 cell / mm2, while in the advanced KCN group (stages 3 and 4) it was 2670.6 ± 262.7 cell / mm2 , p = 0.24. Conclusions: No correlation was found between the endothelial cell count and the KCN stage.

Comparación de las características de la córnea entre individuos chinos y cubanos / Comparison between corneal features of Chinese and Cuban subjects

Objetivo: Comparar las características de la córnea entre individuos chinos y cubanos adultos sanos. Métodos: Se realizó un estudio observacional, descriptivo, transversal, en 120 ojos de individuos sanos (60 chinos y 60 cubanos), entre 18 y 29 años de edad, entre septiembre del año 2016 y diciembre de 2017 en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Se evaluó la edad, el sexo, la queratometría, la paquimetría y las características del endotelio corneal. Resultados: Predominó el sexo femenino (53,3 por ciento en los cubanos y 66,6 por ciento en los chinos). La edad promedio fue de 24,4 años en ambos grupos. La queratometría promedio resultó mayor en el grupo de estudio de cubanos, con un valor de 44,7 y 44,6 dioptrías en ambos ojos, respectivamente. El espesor corneal fue de 607,3-629,9 en los cubanos y de 575,4-607,2 en los chinos. El coeficiente de variación, la desviación estándar y la densidad celular se diferenciaron mínimamente en ambos ojos para ambas nacionalidades, y resultaron superiores en los ojos izquierdos con un coeficiente de 32,0 (±11,0) en los chinos. La desviación estándar promedio fue de 112,0 (± 36,5) en ambos grupos y en el ojo derecho la densidad celular fue 2 857,1 (± 240,0 cél/mm2) en los chinos y 2 760,0 (± 367,2) en los cubanos. El average de los cubanos estuvo entre 369,0 y 380, y para los chinos entre 352,4 y 358,4 en los ojos derecho e izquierdo. Conclusiones: Existen diferencias significativas en los valores queratométricos. El espesor corneal resulta discretamente más reducido en los chinos. El coeficiente de variación, la densidad celular, el average y la desviación estándar no presentan diferencias estadísticamente significativas(AU)

Objective: Compare the corneal features of Chinese and Cuban healthy adult subjects. Methods: A cross-sectional observational descriptive study was conducted of 120 eyes of healthy 18-29 year old individuals (60 Chinese and 60 Cuban) from September 2016 to December 2017 at Ramón Pando Ferrer Cuban Institute of Ophthalmology. The variables analyzed were sex, keratometry, pachymetry and characteristics of the corneal endothelium. Results: Female sex prevailed (53.3 percent among Cuban and 66.6 percent among Chinese subjects). Mean age was 24.4 years in both groups. Mean keratometry was higher in the Cuban group, with values of 44.7 and 44.6 diopters for both eyes, respectively. Corneal thickness was 607.3-629.9 among Cuban and 575.4-607.2 among Chinese subjects. Variation coefficient, standard deviation and cell density were minimally different between the two eyes in both groups, and were higher in left eyes of Chinese subjects with a coefficient of 32.0 (±11.0). Mean standard deviation was 112.0 (± 36.5) in both groups, whereas right eye cell density was 2 857.1 (± 240.0 cell/mm2) among Chinese and 2 760.0 (± 367.2) among Cuban subjects. Average between right and left eyes ranged from 369.0 to 380 for the Cubans and from 352.4 to 358.4 for the Chinese. Conclusions: Significant differences were found between keratometric values. Corneal thickness was slightly lower among Chinese subjects. Variation coefficient, cell density, average and standard deviation did not show any statistically significant differences(AU)

Influence of upper blepharoplasty on intraocular lens calculation / A influência da blefaroplastia superior no cálculo da lente intraocular

ABSTRACT Purpose: To determine the effect of upper blepharoplasty on corneal topography and intraocular lens power calculation using Galilei and IOLMaster. Methods: Thirty patients submitted to upper blepharoplasty from May 2014 to March 2017 at the Hospital Oftalmológico de Sorocaba (São Paulo, Brazil) were included in this observational case series. All patients underwent imaging sessions with Galilei and IOLMaster preoperatively (baseline) and at 1 and 6 months postoperatively. Primary outcome measures using both devices included flattest, average, and steepest corneal curvature, corneal astigmatism, and blepharoplasty-induced corneal astigmatism. Determination of axial length and lens power calculation were performed using only IOLMaster (Holladay formula). Paired t-test and vectorial analysis were used for statistical analysis. Results: Sixty eyes from 30 patients were prospectively included. Vectorial analysis showed that 6 months after surgery, blepharoplasty induced on average 0.39 D and 0.31 D of corneal astigmatism, as measured with Galilei and IOLMaster, respectively. IOLMaster measurements showed that average corneal curvature (44.56 vs 44.64 D, p=0.01), steepest corneal curvature (45.17 vs 45.31, p=0.01) and corneal astigmatism (1.22 vs 1.34, p=0.03) were higher 6 months after surgery. IOLMaster measurements also showed that intraocular lens power was significantly smaller 6 months after surgery (22.07 vs 21.93, p=0.004). All other parameters showed no change for comparisons between baseline and 6 months (p>0.05 for all comparisons). Conclusion: Upper eyelid blepharoplasty influenced intraocular lens calculation using the IOLMaster. However, the influence was not clinically significant. No topographic changes were found using Galilei.

RESUMO Objetivo: Determinar o efeito da blefaroplastia superior na topografia corneana e no cálculo do poder das lentes intraoculares usando Galilei e IOLMaster. Métodos: Trinta pacientes submetidos a blefaroplastia superior de maio de 2014 a março de 2017 no Hospital Oftalmológico de Sorocaba, São Paulo, Brasil foram incluídos neste estudo de série de casos observacional. Todos os pacientes foram submetidos a sessões de imagem com Galilei e IOLMaster antes da cirurgia (exame de base) e no 1º e 6º mês pós-operatório. Os resultados primários utilizando os dois aparelhos incluíram ceratometria, astigmatismo corenano e astigmatismo corneano induzido pela blefaroplastia. O comprimento axial e o cálculo do poder da lente intraocular foram realizados unicamente com o IOLMaster (fórmula de Holladay). Teste-t pareado e análise vetorial foram usados na análise estatística. Resultados: Sessenta olhos de 30 pacientes foram incluídos prospectivamente. A análise vec­torial mostrou que após 6 meses da cirurgia, a blefaroplastia superior induziu na média 0,39 D de astigmatismo corneano medido com o Galilei e 0,31 D com IOLMaster. As medidas com o IOLMaster mostraram que a ceratometria média (44,56 vs 44,64 D, p=0,01), ceratometria máxima (45,17 vs 45,31, p=0,01) e o astigmatismo corneano (1,22 vs 1,34, p=0,03) foram maiores após 6 meses da blefaroplastia. As medidas com IOLMaster mostraram que o poder da lente intraocular foi significativamente menor 6 meses após a blefaroplastia (22,07 vs 21,93, p=0,004). Todos os outros parâmetros não mostraram mudanças entre o pré-operatório e o 6º mês da cirurgia (p>0,05 para todas as comparações). Conclusões: A blefaroplastia superior influenciou o cálculo da lente intrao­cular utilizando o IOLMaster. Contudo, a influência não foi cli­­nicamente significativa. Não foram encontradas mudanças topográficas com o Galilei.

Efficacy and safety of accelerated corneal collagen cross-linking in patients with keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To study the efficacy and safety of accelerated collagen cross-linking in keratoconus.<p>METHODS: Medical records of keratoconic corneas underwent accelerated collagen cross-linking at King Chulalongkorn Memorial Hospital, Thailand between April 2015 and August 2018 were reviewed. Preoperative and postoperative data at 1a of visual acuity, auto-refraction, corneal topography, higher-order aberrations(HOA), topometric indices and corneal densitometry were evaluated. Age of 24 and 30 years old, maximum keratometry value(Kmax)of 55 D, and baseline best corrected visual acuity(BCVA)of 20/40(or 0.3 in LogMAR unit)were used as cut-off values to highlight the cross-linking effects. The effect of age, preoperative Kmax and BCVA were analyzed. The association between the change of corneal densitometry and other factors including preoperative Kmax, Kmean, manifest refraction spherical equivalent(MRSE), visual acuity, thinnest pachymetry, the change in Kmax, and the change of those parameters were also analyzed. <i>P</i><0.05 was considered statistically significant.<p>RESULTS: One hundred and fifty-five patients(185 eyes)were included. One hundred and nineteen patients were male and thirty-six patients were female. According to Amsler-Krumeich classification, stages 1 and 2 were dominant(37.84% and 35.14% respectively). At 1a, mean LogMAR uncorrected visual acuity(UCVA)improved by 0.1(<i>P</i><0.05). The number of eyes of which postoperative BCVA improved more than 0.2 LogMAR was higher in the worse baseline BCVA group(preoperative BCVA ≥0.3)compared to the better baseline BCVA group(preoperative BCVA < 0.3)(78.26% <i>vs</i> 21.74%, <i>P</i><0.05). Mean Kmax decreased from baseline by 2.36 diopters(D)(<i>P</i><0.05). Seventy-three percent of the eyes of which Kmax reduced more than 2.0 D had preoperative Kmax ≥55 D. Corneal HOA at 6 mm from corneal apex decreased by 0.40(<i>P</i><0.05). Corneal densitometry at 0-6 mm zone increased at 1mo and persisted 1a postoperatively(<i>P</i><0.05). The relationship of the increase in densitometric value and the decrease of thinnest pachymetry at 1a were in linear fashion. Index of surface variance, index of vertical asymmetry, keratoconus index, index of height decentration decreased at 1a(<i>P</i><0.05). Success rate at 1a was 90.24%. Postoperative corneal haze was found 11.35%, 30.27%, 15.67%, 10.27% and 2.16% at 1wk, 1, 3, 6mo and 1a respectively. No eyes developed corneal edema. There was one case of sterile keratitis.<p>CONCLUSION: Accelerated collagen cross-linking in keratoconus was effective to flatten, reshape the cornea, improved visual acuity, HOA and topometric indices. Great Kmax reduction was found in advanced keratoconus. The magnitude of Kmax reduction is also greatest among previous reports.

Influência da espessura dos segmentos de anel corneano na correção do astigmatismo ceratométrico em pacientes com ceratocone / Influence of corneal ring segment thickness on correction of corneal astigmatism in patients with keratoconus

RESUMO Objetivo: Avaliar retrospectivamente a influência da espessura do anel intracorneano na redução do astigmatismo corneano em pacientes portadores de ceratocone. Métodos: De um banco de dados com 2.033 olhos submetidos à cirurgia de implante de anel corneano, foi selecionada uma amostra de 90 olhos com características semelhantes em relação à ceratometria e ao astigmatismo. Todos os olhos deste estudo receberam dois segmentos de comprimento de arco tradicional de aproximadamente 160°, com espessuras variadas: Grupo A recebeu dois segmentos de 150µm; Grupo B recebeu dois segmentos de 200µm, e Grupo C recebeu dois segmentos de 250µm. As variáveis analisadas foram ceratometria média e astigmatismo corneano pré e pós-operatório. Resultados: Nos olhos que receberam dois segmentos de anel de 150µm de espessura (Grupo A), houve redução média de 5,0D (10%) em relação à ceratometria média e redução média de 3,26D (57,69%) em relação ao astigmatismo corneano. Na amostra em que foram utilizados dois segmentos de 200µm (Grupo B), foi observada redução da ceratometria média de 7,0D (14,28%) e do astigmatismo corneano de 3,53D (63,6%). Já na amostra que recebeu dois segmentos de anel de 250µm de espessura (Grupo C), a redução média da ceratometria foi de 10D (20,4%) e de seu astigmatismo corneano de 2,09D (38,99%). Conclusão: Nos pacientes com ceratocone submetidos à cirurgia de anel corneano, o aumento da espessura dos segmentos implantados promove maior aplanamento da córnea, mas não o aumento em sua capacidade de reduzir o astigmatismo ceratométrico. Seria interessante a análise de uma amostra maior de pacientes, aliada a cálculos vetoriais de astigmatismo, para comprovar os achados deste estudo.

ABSTRACT Objective: To retrospectively evaluate the influence of intracorneal ring thickness on reduction of corneal astigmatism in patients with keratoconus. Methods: From a database of 2,033 eyes submitted to corneal ring implant surgery, a sample of 90 eyes with similar keratometry and astigmatism characteristics was selected. All eyes in this study received two segments of traditional arc length of approximately 160°, with varying thicknesses: Group A received two segments of 150 µm; Group B received two segments of 200 µm, and Group C received two segments of 250 µm. The variables analyzed were mean keratometry and corneal astigmatism before and after surgery. Results: In the eyes that received two 150-µm ring segments (Group A), there was a mean reduction of 5.0 D (10%) in relation to mean keratometry, and a mean reduction of 3.26 D (57.69%) in relation to corneal astigmatism. In the sample in which two 200-µm segments (Group B) were used, there was a mean reduction in keratometry of 7.0 D (14.28%) and in corneal astigmatism of 3.53 D (63.6%). In the sample receiving two 250-µm ring segments (Group C), the mean reduction in keratometry was 10 D (20.4%) and in corneal astigmatism was 2.09 D (38.99%). Conclusion: In keratoconus patients undergoing corneal ring surgery, increased thickness of the implanted segments promotes greater flattening of the cornea, but does not enhance their ability to reduce corneal astigmatism. It would be interesting to analyze a larger sample of patients, combined with vector calculations of astigmatism, to confirm the findings of this study.

Keratometric changes after pterygium excision

Background: A pterygium is a wing-shaped growth of conjunctiva and fibrovascular tissue on the superficial cornea. The pathogenesis of pterygia is strongly correlated with UV light exposure and environmental factors. The prevalence of pterygia increases steadily with proximity to the equator, and the condition is more common in men than women. It is well established fact that before entering the optical zone pterygium causes flattening of the cornea in horizontal meridian with the more normal side of the cornea usually temporally, resulting in with-the-rule astigmatism.Methods: The study included 80 patients of primary pterygium who underwent pterygium excision with conjunctival autograft adhered by autologous blood surgery. After performing routine ocular examination which includes visual acuity without and with pinhole and pre-operative keratomery was assessed by autokeratorefractometer. Repeat examination was performed after 6 weeks of surgery. Patients with recurrent pterygium, pseudo-pterygium, and history of previous ocular surgery were excluded.Results: The pre‑ and postoperative corneal astigmatism were compared after 6 weeks of surgery. The changes in corneal astigmatism were statistically significant p value <0.001. The preoperative mean corneal astigmatism of 3.41 D was reduced to 1.59 D (p value <0.001) 6 weeks after surgery, but maximum change in astigmatism was seen in Grade IV >Grade III >Grade II >Grade I.Conclusions: Primary pterygium of all grades treated with well accepted technique pterygium excision with conjunctival autograft with autologous blood gives promising results in terms of improvement in corneal astigmatism and hence visual acuity as well.

Repeatability and reproducibility of a swept-source optical coherence tomography biometer IOL Master 700 in healthy eyes / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the repeatability and reproducibility of ocular biological measurements by a swept-source optical coherence tomography biometer IOL Master 700 in healthy eyes. <p>METHODS: A diagnostic test study of 103 healthy subjects was implemented. The right eyes were selected for measurements. Ocular biological parameters including axial length(AL), anterior chamber depth(ACD), anterior aqueous depth(AQD), keratometry readings(K), central corneal thickness(CCT), lens thickness(LT), white-to-white corneal diameter(WTW)and pupil diameter(PD)were measured using IOL Master 700 by two experienced examiners. One-way ANOVA was used to evaluate the repeatability and reproducibility for the measurements by IOL Master 700. <p>RESULTS: Regarding repeatability, the test-retest repeatability(TRT)for AL, mean K(Km), K1, K2, ACD, AQD, LT, CCT, WTW and PD obtained by the two examiners were 0.018(0.017)mm, 0.215(0.270)D, 0.325(0.334)D, 0.303(0.366)D, 0.049(0.041)mm, 0.048(0.042)mm, 0.058(0.047)mm, 6.168(5.779)μm, 0.395(0.406)mm, and 1.097(1.099)mm, respectively; the relative coefficient of variation(CoV)for all measured parameters but the PD were ≤1.219%; the intraclass correlation coefficient(ICC)for all measured parameters were ≥0.815. Regarding reproducibility, the TRT for AL, Km, K1, K2, ACD, AQD, LT, CCT, WTW, and PD obtained were 0.018 mm, 0.240 D, 0.329 D, 0.337 D, 0.048 mm, 0.048mm, 0.055mm, 6.396μm, 0.420mm, and 1.144mm, respectively; the ICC for all measured parameters was ≥0.900; the CoV for all measured parameters were ≤1.263% CoV, except for the PD(8.750%). In addition, the ICC of AL measurement for both repeatability and reproducibility were 1.000. <p>CONCLUSION: With the exception of pupil diameter, IOL Master 700 demonstrates excellent repeatability and reproducibility in ocular biological measurements for healthy eyes, especially in measurement of axial length.

Repeatability and reproducibility of a swept-source optical coherence tomography biometer IOL Master 700 in healthy eyes / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the repeatability and reproducibility of ocular biological measurements by a swept-source optical coherence tomography biometer IOL Master 700 in healthy eyes. <p>METHODS: A diagnostic test study of 103 healthy subjects was implemented. The right eyes were selected for measurements. Ocular biological parameters including axial length(AL), anterior chamber depth(ACD), anterior aqueous depth(AQD), keratometry readings(K), central corneal thickness(CCT), lens thickness(LT), white-to-white corneal diameter(WTW)and pupil diameter(PD)were measured using IOL Master 700 by two experienced examiners. One-way ANOVA was used to evaluate the repeatability and reproducibility for the measurements by IOL Master 700. <p>RESULTS: Regarding repeatability, the test-retest repeatability(TRT)for AL, mean K(Km), K1, K2, ACD, AQD, LT, CCT, WTW and PD obtained by the two examiners were 0.018(0.017)mm, 0.215(0.270)D, 0.325(0.334)D, 0.303(0.366)D, 0.049(0.041)mm, 0.048(0.042)mm, 0.058(0.047)mm, 6.168(5.779)μm, 0.395(0.406)mm, and 1.097(1.099)mm, respectively; the relative coefficient of variation(CoV)for all measured parameters but the PD were ≤1.219%; the intraclass correlation coefficient(ICC)for all measured parameters were ≥0.815. Regarding reproducibility, the TRT for AL, Km, K1, K2, ACD, AQD, LT, CCT, WTW, and PD obtained were 0.018 mm, 0.240 D, 0.329 D, 0.337 D, 0.048 mm, 0.048mm, 0.055mm, 6.396μm, 0.420mm, and 1.144mm, respectively; the ICC for all measured parameters was ≥0.900; the CoV for all measured parameters were ≤1.263% CoV, except for the PD(8.750%). In addition, the ICC of AL measurement for both repeatability and reproducibility were 1.000. <p>CONCLUSION: With the exception of pupil diameter, IOL Master 700 demonstrates excellent repeatability and reproducibility in ocular biological measurements for healthy eyes, especially in measurement of axial length.

Post-small incision lenticule extraction phacoemulsification with multifocal IOL implantation: A case report

A 54-year-old patient presented with cataract, 5 years after undergoing SMILE for high myopia in both eyes. He was motivated in achieving spectacle free vision and his post SMILE-induced aberrations were minimal, due to which he was found suitable for a trifocal IOL implant. Of the various methods considered, the IOL power predicted by a novel combined telecentric keratometry and swept source OCT-based method was finally selected. One month post-operatively, the patient achieved a binocular UDVA of 20/20p and near vision of N.6, suggesting that newer IOL formulae could be superior in providing satisfactory outcomes in post refractive patients.

Effect of Pterygium Surgery on Keratometry Readings

Introduction: In many case Pterygium is found to causeastigmatism. Study aimed to find the effect of pterygiumexcision on keratomerty readings.Material and Methods: The present Retrospective study wasdone on 50 eyes of 50 patients, who had primary pterygiumand underwent pterygium surgery during period of October2016 to October 2017 in a tertiary care hospital. Informationthat was reviewed included preoperative uncorrected and bestcorrected visual acuity, auto refraction, auto keratometry anddetailed anterior segment and posterior segment examination.Results: Mean astigmatism changed from preoperative 5.94 ±3.82 Diopters (D) to 1.30 ± 1.07 D on 30th post operative dayshowing 4.64 ± 2.75 D of change in astigmatism.Conclusion: Pterygium can be a cause of low vision secondaryto corneal astigmatism. Pterygium excision reduces cornealastigmatism significantly, which improves vision.

La queratometría como variable predictora de la ametropía: un estudio diagnóstico en la población escolarizada de 5 a 19 años de la ciudad de pereira

Objetivo: determinar la relación entre la curvatura corneal y los defectos de refracción en la población estudiantil de 5 a 19 años de la ciudad de Pereira en el año 2014. Materiales y métodos: el tipo de estudio es observacional correlacional descriptivo. Se indica el modelo de regresión lineal simple entre la queratometría y la retinoscopía. Se evaluó el error refractivo en 915 estudiantes de Pereira mediante retinoscopía estática y queratometría. Resultados: el valor cilíndrico obtenido para el ojo derecho (OD) oscila entre -0,12 y -5,50 dpt, mientras que para el ojo izquierdo (OI), el valor oscila entre -0,12 y -6,12 dpt. El 86,6% del meridiano eje (ME) del OD está entre 38,00 y 43,88 dpt, en tanto que el 87,2% del ME del OI se encuentra entre 32,00 y 43,88 dpt. La ametropía positiva para el OD está entre 0,25 y 8,00 dpt; para el OI en 0,25 y 7,50dpt. La ametropía negativa está en 6,00 para el OD y 6,50 dpt para el OI como valores máximos. En relación a la curvatura corneal y a las ametropías, el OD muestra una correlación de Pearson negativa, de -0,21 (p=0.0001). En el OI la correlación de Pearson también es negativa, de -0,20 (p=0.0001). Por lo tanto, la relación encontrada entre estas dos variables es tan solo del 5,1% y un 4,7% para OD y OI, respectivamente. Conclusiones: la relación entre la curvatura corneal y los errores de refracción según este modelo solo explica un porcentaje insignificante que no tiene importancia clínica, es del 4,9% en promedio del valor obtenido en el error refractivo en ambos ojos. Por ello, no es posible hacer una predicción de los errores refractivos con base en el radio de la curvatura corneal.

Objective: The purpose of this research was to determine the relationship between corneal curvature and refractive errors in schooled population between the ages of 5 to 19 in the city of Pereira in 2014. Materials and Methods: This is a descriptive correlational observational study, in which the simple linear regression model between keratometry and retinoscopy is indicated. Through static retinoscopy and keratometry, refractive error was evaluated in 915 students of Pereira. Results: The cylindrical value obtained for the RE (right eye) oscillates between -0.12 and -5.50 dpt and for the LI (left eye) -0.12 and -6.12 dpt, where 86.6% of the Axis (ME in Spanish) RE is between 38.00 and 43.88dpt, while 87.2% of Axis LE is between 32.00 and 43.88dpt. The positive ametropia for the RE is between 0.25 and 8.00dpt, for the LE 0.25 and 7.50dpt, the negative in RE 6.00 and OI 6.50dpt as maximum values. In relation to corneal curvature and ametropias, the RE shows a negative Pearson correlation of -0.21 (p = 0.0001). In the LE the Pearson correlation is also negative, of -0.20 (p = 0.0001). Therefore, the relationship found between these two variables is only 5.1% and 4.7% for RE and LE respectively. Conclusions: The relationship between corneal curvature and refractive errors according to this model only explains an insignificant percentage that does not have clinical importance, it is a 4.9% on average of the value obtained in the refractive error in both eyes, therefore, it does not allow a prediction of refractive errors based on the radius of corneal curvature.

Objetivo. O objetivo desta pesquisa foi determinar a relação entre a curvatura da córnea e erros de refração na população estudantil de 5 a 19 anos de idade na cidade de Pereira em 2014. Materiais e Métodos. 0 tipo de estudo é descritivo correlacional observacional, no qual o modelo de regressão linear simples entre ceratometria e retinoscopia é indicado. Por meio de retinoscopia estática e ceratometria, o erro refrativo foi avaliado em 915 estudantes de Pereira. Resultados. O valor cilíndrico obtido para o OD (olho direito) é entre -0,12 e -5,50dpt e para o OI (olho esquerdo) e -0,12dpt e -6,12, onde 86,6% do Meridiano Eje (ME) OD está entre 38,00 e 43,88dpt, enquanto que 87,2% do ME 01 está entre 32,00 e 43,88dpt. A ametropia positiva para o OD está entre 0,25 e 8,00dpt, para o OI 0,25 e 7,50dpt, a ametropia negativa em OD 6,00 e OI 6,50dpt como valores máximos. Em relação à curvatura corneana e ametropias, o OD mostra uma correlação negativa de Pearson de -0,21 (p = 0,0001). No OI, a correlação de Pearson também é negativa, de -0,20 (p = 0,0001). Portanto, a relação encontrada entre essas duas variáveis é de apenas 5,1% e 4,7% para OD e OI, respectivamente. Conclusões. A relação entre a curvatura corneana e os erros refra-tivos de acordo com este modelo explica apenas uma percentagem insignificante de nenhuma importância clínica, é de 4,9%, em média, do valor obtido no erro refrativo em ambos os olhos, de modo que, não permite fazer uma previsão de erros refrativos com base no raio da curvatura corneana.

Agreement of biometry parameters measured by IOLMaster 700 with IOLMaster 500 in cataract eyes with high myopia / 中华实验眼科杂志

Objective To compare the agreement of axial length (AL),anterior chamber depth (ACD) and keratometry measured by IOLMaster 500 with IOLMaster 700 in cataract eyes with high myopia.Methods A cross-sectional study was performed.One hundred and fifty-two eyes of 87 cataract patients with high myopia were included from September to October 2017 in Beijing Tongren Hospital.The best corrected visual acuity (BCVA) was 0.05-1.0,and the refraction power was-6.25--21.00 D,with an average power of (-13.625 ± 7.375) D.A L,ACD and keratometry (Kf,Ks) were measured by IOLMaster 700 and IOLMaster 500 respectively for all the eyes.The eyes were assigned to AL＞26-≤28 mm group,AL＞28-＜30 mm group and AL≥30 mm according to the results of IOLMaster 500.The measured differences between two devices were assessed using paired samples t-test,and the measured consistency of the two devices was evaluated using Bland-Altman agreement analysis.This study protocol was approved by Ethics Committee of Beijing Tongren Hospital and complied with Declaration of Helsinki.Results There were no significant differences in the AL and Kf measured by the two devices in all the three groups (all at P＞0.05).Both ACD and Ks values measured by IOLMaster 700 were lower than those by IOLMaster 500 (both at P＜0.05),which were clinically acceptable.The percentage beyond 95％ agreement limit between IOLMaster 700 and IOLMaster 500 were 4.10％,2.17％ and 3.03％ for AL differences and 4.10％,4.34％ 和 3.03％ for Kf difference in the three groups.Significant differences were found in ACD and Ks between IOLMaster 700 and IOLMaster 500 at a clinically acceptable level (both at P＜0.05),and Bland-Altamn agreement analysis showed that the percentage beyond 95％ agreement limit between IOLMaster 700 and IOLMaster 500 were 4.10％,4.34％ and 3.03％ for both ACD and Ks differences in the three groups.Conclusions There is a good agreement in AL,ACD,Kf and Ks measured by IOLMaster 700 with IOLMaster 500 and is clinically interchangeable in cataract eyes with high myopia.However,IOLMaster 700 is better because it can provide the OCT image of macula.