Evaluation of unilateral corneal collagen cross-linking on fellow untreated eyes of patients with keratoconus / A avaliação da reticulação unilateral do colágeno corneano em olhos não tratados de pacientes com ceratocone

ABSTRACT Purpose: This study aimed to examine the effects of unilateral corneal collagen cross-linking treatment on visual acuity and the topographic findings of the fellow untreated eye of patients who had bilateral progressive keratoconus. Methods: Patients with progressive keratoconus who underwent cross-linking treatment were screened retrospectively. A total of 188 untreated eyes of 188 patients whose eyes were treated unilaterally with either standard or accelerated cross-linking and refused cross-linking procedure for the fellow eye were included. Visual acuity and topographic findings of the fellow untreated eyes were obtained preoperatively and postoperatively at the 1st, 3rd, 6th, 12th, 24th, 30th, and 36th months. Results: The change over time of variables examined was similar in the untreated eyes of patients who received standard and accelerated cross-linking methods (p>0.05). At the 12th month, 136 (95.8%) untreated eyes were stable according to progression criteria. Only 4 (8%) eyes were progressive at the 24th month. No progression was observed in any of the 16 patients with a 36-month follow up. Conclusions: The results showed that the fellow untreated eyes of patients with bilateral progressive keratoconus did not have significant progression rates after unilateral cross-linking treatment.

RESUMO Objetivo: Examinar os efeitos do tratamento de reticulação unilateral do colágeno corneano na acuidade visual e os achados topográficos em olhos não tratados de pacientes com ceratocone progressivo bilateral. Métodos: Foram rastreados retrospectivamente pacientes com ceratocone progressivo submetidos a tratamento de reticulação. Foram incluídos no estudo 188 olhos não tratados de 188 pacientes tratado unilateralmente com reticulação padrão ou acelerada e que recusaram o procedimento de reticulação no outro olho. A acuidade visual e os achados topográficos dos olhos não tratados foram obtidos no pré- e pós-operatório no 1º, 3º, 6º, 12º, 24º, 30º e 36º mês. Resultados: As alterações ao longo do tempo foram semelhantes para as variáveis examinadas nos olhos não tratados de pacientes tratados com métodos de reticulação padrão e acelerado (p>0,05). No 12º mês, 136 olhos não tratados (95,8%) estavam estáveis, de acordo com os critérios de progressão. Apenas quatro olhos (8%) mostraram progressão no 24º mês. Nenhuma progressão foi observada nos 16 pacientes que tiveram um acompanhamento de 36 meses. Conclusões: O estudo mostrou que os olhos não tratados de pacientes com ceratocone progressivo bilateral não apresentaram taxas de progressão significativas após o tratamento unilateral com reticulação.

Corneal reshaping: an experiment with a type I collagen-based vitrigel for remodeling porcine corneas / Remodelamento corneano: relato de um experimento com um vitrigel a base de colágeno tipo I para remodelamento de córneas porcinas

ABSTRACT Purpose: This study aimed to report an experiment designed to determine anatomical changes in porcine corneas following placement of a novel polymer implant into the cornea. Methods: An ex vivo porcine eye model was used. A novel type I collagen-based vitrigel implant (6 mm in diameter) was shaped with an excimer laser on the posterior surface to create three planoconcave shapes. Implants were inserted into a manually dissected stromal pocket at a depth of approximately 200 μm. Three treatment groups were defined: group A (n=3), maximal ablation depth 70 μm; Group B (n=3), maximal ablation depth 64 μm; and group C (n=3), maximal ablation depth 104 μm, with a central hole. A control group (D, n=3) was included, in which a stromal pocket was created but biomaterial was not inserted. Eyes were evaluated by optical coherence tomography (OCT) and corneal tomography. Results: Corneal tomography showed a trend for a decreased mean keratometry in all four groups. Optical coherence tomography showed corneas with implants placed within the anterior stroma and visible flattening, whereas the corneas in the control group did not qualitatively change shape. Conclusions: The novel planoconcave biomaterial implant described herein could reshape the cornea in an ex vivo model, resulting in the flattening of the cornea. Further studies are needed using in vivo animal models to confirm such findings.

RESUMO Objetivo: Relatar um experimento projetado para determinar alterações anatômicas em córneas porcinas após a colocação de um novo implante de polímero na córnea. Métodos: Foi utilizado olho de porco ex vivo. Um novo agente modelador biocompatível, de colágeno tipo 1, com 6mm de diâmetro foi moldado com excimer laser em sua face posterior, para criar três formatos planocôncavos. Os implantes foram inseridos dentro de um bolsão, dissecado manualmente, a 200 micrômetros (μm). Foram definidos três grupos de tratamento: grupo A (n=3), teve a profundidade máxima de ablação de 70 μm; o grupo B (n=3), profundidade máxima de ablação de 64 μm; e o grupo C (n=3), profundidade máxima de ablação de 104 μm, com buraco central. O grupo controle, D (n=3), foi incluído, com a criação do bolsão estromal, porém sem inserir o material. A avaliação desses olhos foi realizada por tomografia de coerência óptica (OCT) e por tomografia corneana. Resultados: A tomografia corneana mostrou uma tendência para diminuição da ceratometria média em todos os 4 grupos. A tomografia de coerência óptica mostrou córneas com implantes localizados no estroma anterior e aplanamento visível, enquanto as córneas não mudaram qualitativamente o formato no grupo controle. Conclusões: O novo implante de biomaterial planocôncavo descrito aqui foi capaz de remodelar a córnea em modelo de animal ex vivo, resultando no aplanamento corneano. Novos estudos são necessários usando modelos animais in vivo para confirmar tais achados.

Evaluation of corneal tomography in children and adolescents without ocular or systemic allergy / Avaliação da tomografia de córnea em crianças e adolescentes sem alergia ocular ou sistêmica

ABSTRACT Purpose: To determine normal corneal tomographic parameters in children and adolescents without corneal disease or atopy diagnosis. Methods: This descriptive cross-sectional study evaluated patients aged 8-16 years who underwent a complete slit-lamp biomicroscopic examination and tomographic corneal evaluation by a dual Scheimpflug analyzer, excluding those with ocular disease (including allergic conjunctivitis) or a positive prick test for systemic atopies. Results: A total of 170 patients were evaluated, and 34 patients (68 eyes) were analyzed once the exclusion criteria were applied. The sample's mean age was 10.76 ± 2.31 years; with 19 (55.9%) men and 15 (44.1%) women. The mean keratometry in the flat meridian (Kflat), steep meridian (Ksteep), and maximum (Kmax) were 42.37 ± 1.63D, 43.53 ± 1.65D, and 43.90 ± 1.73D, respectively. The mean values for corneal asphericity (ε2) and thinnest point were 0.28 ± 0.11 and 550.20 ± 37.90 μm, respectively. The inferior-superior asymmetry ratio (I-S) and coma were 0.74 ±0.59D and 0.28 ± 0.12D, respectively. Conclusion: The knowledge of normal corneal tomographic parameters and their variation in children and adolescents without corneal disease or atopy may be useful for diagnosing keratoconus and initiating early disease treatment.

RESUMO Objetivo: Identificar parâmetros tomográficos de normalidade em córneas de crianças e adolescentes sem a presença de atopias sistêmicas e alergias oculares. Métodos: Este estudo descritivo transversal avaliou pacientes com idade entre 8 e 16 anos que foram submetidos a exame biomicroscópico completo por lâmpada de fenda e avaliação tomográfica da córnea por tomógrafo dual Scheimpflug, excluindo pacientes com doença ocular (incluindo conjuntivite alérgica) ou prick test positivo para atopias sistêmicas. Resultados: Cento e setenta pacientes foram avaliados e após cumpridos os critérios de exclusão, 34 (68 olhos) foram analisados. A média etária da amostra foi 10,76 ± 2,31 anos; 19 (55,9%) eram meninos e 15 (44,1%) meninas. A média da ceratometria em dioptrias (D) no meridiano mais plano (Kflat), mais curvo (Ksteep) e máxima (Kmax) foram 42,37 ± 1,63D, 43,53 ± 1,65D e 43,90 ± 1,73D, respectivamente. Os valores médios da asfericidade corneana (ε2) e do ponto mais fino da córnea foram 0,28 ± 0,11 e 550,20 ± 37,90 micras (μm). A assimetria corneana inferior-superior (I-S) e coma foi em média 0,74 ± 0,59D e 0,28 ± 0,12D, respectivamente. Conclusão: O conhecimento dos valores médios e sua variação de parâmetros tomográficos da córnea em crianças e adolescentes sem atopias sistêmicas ou alergias oculares pode ser útil para o diagnóstico precoce do ceratocone e o seu tratamento em estágio inicial.

Post-Bader procedure: a long-term follow-up case study / Procedimento pós-Bader: estudo de caso com acompanhamento de longo prazo

ABSTRACT Keratoconus is a progressive disorder that manifests as a cone-like steepening of the central or paracentral inferior cornea and irregular stromal thinning. There is a gradual decrease in visual acuity due to corneal asymmetry, irregular astigmatism, and increased optical aberrations, consequently impacting the quality of life. Several procedures have been developed in an attempt to slow or reverse the progression. The Bader procedure, which includes a pattern of incisions around the circumference of the cornea and at the base of the protruding cone, is one such surgery. These incisions penetrate 70-90% of the cornea's depth. Its goal is to flatten the topography and reduce corneal asymmetry and irregular astigmatism. Though prior research found these to be highly promising, we report a patient who was given contact lenses to restore and maintain his vision while his corneal ectasia and thinning progressed over the following decade.

RESUMO O ceratocone é uma doença progressiva que se manifesta como uma elevação semelhante a um cone da cór­nea central ou paracentral inferior e é associada a uma re­dução irregular da espessura do estroma. Há uma diminuição gradual da acuidade visual devido à assimetria da córnea, ao astigmatismo irregular e a um aumento das aberrações ópticas, o que prejudica a qualidade de vida. Foram desenvolvidos vários procedimentos para tentar interromper ou mesmo reverter a evolução da doença. Um deles é o chamado procedimento de Bader, que inclui um padrão de incisões em volta da circunferência da córnea e na base do cone protuberante. Essas incisões penetram até 70%-90% da profundidade da córnea e têm o objetivo de achatar a topografia e diminuir a assimetria da córnea e o astigmatismo irregular. Embora essa técnica seja muito promissora, segundo um estudo anterior, aqui se apresenta o caso de um paciente no qual esses objetivos não foram atingidos. Esse paciente recebeu lentes de contato para restaurar e manter sua visão, enquanto sua ectasia corneana e a redução da espessura progrediram ao longo da década seguinte.

Therapeutic effects of orthokeratology lens combined with 0.01% atropine eye drops on juvenile myopia / Efeitos terapêuticos da lente de ortoceratologia combinados com colírio atropina 0,01% em miopia juvenil

ABSTRACT Purpose: To explore the therapeutic effects of orthokeratology lens combined with 0.01% atropine eye drops on juvenile myopia. Methods: A total of 340 patients with juvenile myopia (340 eyes) treated from 2018 to December 2020 were divided into the control group (170 cases with 170 eyes, orthokeratology lens) and observation group (170 cases with 170 eyes, orthokeratology lens combined with 0.01% atropine eye drops). The best-corrected distance visual acuity, best-corrected near visual acuity, diopter, axial length, amplitude of accommodation, bright pupil diameter, dark pupil diameter, tear-film lipid layer thickness, and tear break-up time were measured before treatment and after 1 year of treatment. The incidence of adverse reactions was observed. Results: Compared with the values before treatment, the spherical equivalent degree was significantly improved by 0.22 (0.06, 0.55) D and 0.40 (0.15, 0.72) D in the observation and control groups after the treatment, respectively (p<0.01). After the treatment, the axial length was significantly increased by (0.15 ± 0.12) mm and (0.24 ± 0.11) mm in the observation and control groups, respectively, (p<0.01). After the treatment, the amplitude of accommodation significantly declined in the observation group and was lower than that in the control group, whereas both bright and dark pupil diameters significantly increase and were larger than those in the control group (p<0.01). After the treatment, the tear-film lipid layer thickness and tear break-up time significantly declined in the two groups (p<0.01). Conclusions: Orthokeratology lens combined with 0.01% atropine eye drops can synergistically enhance the control effect on juvenile myopia with high safety.

RESUMO Objetivo: Explorar os efeitos terapêuticos das lentes de ortoceratologia combinados com colírio atropina 0,01% em miopia juvenil. Métodos: Um total de 340 pacientes com miopia juvenil (340 olhos) tratados entre 2018 e Dezembro de 2020 foram divididos em Grupo Controle (170 casos com 170 olhos, lentes de ortoceratologia) e Grupo Observação (170 casos com 170 olhos, lentes de ortoceratologia combinadas com colírio atropina 0,01%). A acuidade visual melhor corrigida para longe, acuidade visual melhor corrigida para perto, dioptria, comprimento axial, amplitude de acomodação, diâmetro da pupila brilhante, diâmetro da pupila escura, espessura da camada lipídica da película lacrimal e tempo de ruptura do rasgo foram medidos antes do tratamento e 1 ano depois. A incidência de reações adversas foi observada. Resultados: Antes do tratamento, o grau esférico equivalente foi significativamente melhorado em 0,22 (0,06, 0,55) D e 0,40 (0,15, 0,72) D respectivamente no Grupo Observação e no Grupo Controle após o tratamento (p<0,01). Após tratamento, o comprimento axial foi significativamente aumentado em (0,15 ± 0,12) mm e (0,24 ± 0,11) mm respectivamente nos Grupos Observação e controle (p<0,01), enquanto, no grupo de observação, a amplitude de acomodação diminuiu significativamente e foi inferior a do Grupo Controle, e o diâmetro da pupila brilhante e o diâmetro da pupila escura aumentaram significativamente e foram maiores do que os do Grupo Controle (p<0,01). A espessura da camada lipídica da película lacrimal e o tempo de ruptura do rasgo diminuíram significativamente nos dois grupos (p<0,01) após o tratamento. Conclusões: As lentes de ortoceratologia combinadas com colírio atropina 0,01% podem melhorar significativamente o efeito controle em miopia juvenil com elevada segurança.

Ten-year follow-up of corneal cross-linking and refractive surface ablation in patients with asymmetric corneal topography

Purpose: Compare the safety and efficacy of wavefront?guided photorefractive keratotomy (PRK) 6 months after cross?linking (CXL) to wavefront?guided PRK alone for refractive correction in patients with bilateral asymmetric corneal topography. Methods: Prospective randomized clinical trial with 16 patients (32 eyes). CXL with subsequent PRK after 6 months in one eye, and PRK alone was performed in contralateral eyes. The follow?up was 10 years. We analyzed visual outcomes, Scheimpflug topography, and corneal haze evaluation. Results: Eyes in the PRK group showed better results than in the CXL + PRK group. Mean postoperative CDVA was 0.044 logmar (SD, 0.073) in the PRK group and 0.1 logmar (SD, 0.21) in the CXL + PRK group, the mean sphere was + 0.21 (SD, 0.6) D in the PRK group and 0.87 (SD, 2.3) D in the CXL + PRK group, and mean SE was ?0.35 (SD, 0.65) D in the PRK group and 0.62 (SD, 2.32) D in the CXL + PRK group. In one patient, a steepening of 2.5 D and a thinning of 17 ?m occurred in PRK alone group. Two patients in the CXL + PRK group presented corneal haze. The overall complication rate was 18,75% (haze and ectasia). Conclusion: Non?simultaneous CXL and PRK procedures yielded good refractive results, but worse than those obtained with PRK alone. Although one patient in the PRK group developed corneal ectasia, the CXL + PRK group had a higher loss of vision lines, indicating less safety

Postoperative corneal topography generation based on attention mechanism and Pix2Pix network / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To explore the use of attention mechanism and Pix2Pix generative adversarial network to predict the postoperative corneal topography of age-related cataract patients undergone femtosecond laser arcuate keratotomy.METHODS:In this retrospective case series study, the 210 preoperative and postoperative corneal topographies from 87 age-related cataract patients(105 eyes)undergoing femtosecond laser arcuate keratotomy at Shanxi Eye Hospital between March 2018 and March 2020 were selected and divided into a training set(180)and a test set(30)for model training and testing. The peak signal-to-noise ratio(PSNR), structural similarity(SSIM)and Alpins astigmatism vector analysis were used to compare the accuracy of postoperative corneal topography prediction under different attention mechanisms.RESULTS:The model based on attention mechanism and Pix2Pix network can predict postoperative corneal topography, among which the model based on Self-Attention mechanism has the best prediction effect, with PSNR and SSIM reaching 16.048 and 0.7661, respectively. There were no statistically significant differences in the difference vector, difference vector axis position, surgically induced astigmatism, and correction index between real and generated corneal topography on the 3mm and 5mm rings(all P&#x003E;0.05).CONCLUSION:Based on the Self-Attention mechanism and Pix2Pix network, the postoperative corneal topography can be well predicted, which can provide reference for the surgical planning and postoperative effects of ophthalmic clinicians.

Intelligent diagnostic model of keratoconus based on deep learning algorithm / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To establish an intelligent diagnostic model of keratoconus for small-diameter corneas by data mining and analysis of patients' clinical data.METHODS: Diagnostic study. A total of 830 patients(830 eyes)were collected, including 338 male(338 eyes)and 492 female(492 eyes), with an average age of 14-36(23.19±5.71)years. Among them, 731 patients(731 eyes)had undergone corneal refractive surgery at Chongqing Nanping Aier Eye Hospital from January 2020 to March 2022, and 99 patients had a diagnosed keratoconus from January 2015 to March 2022. Corneal diameter ≤11.1 mm was measured by Pentacam in all patients. Two cornea specialists classified patients' data into normal corneas, suspect keratoconus, and keratoconus groups based on the Belin/Ambrósio enhanced ectasia display(BAD)system in Pentacam. The data of 665 patients were randomly selected as the training set and the other 165 patients as the validation set by computer random sampling method. Seven parametric corneal features were extracted by convolutional neural networks(CNN), and the models were built by Residual Network(ResNet), Vision Transformer(ViT), and CNN+Transformer, respectively. The diagnostic accuracy of models was verified by cross-entropy loss and cross-validation method. In addition, sensitivity and specificity were evaluated using receiver operating characteristic curve.RESULTS: The accuracy of ResNet, ViT, and CNN+Transfermer for the diagnosis of normal cornea and suspect keratoconus was 85.57%, 86.11%, and 86.54% respectively, and the area under the receiver operating characteristic curve(AUC)was 0.823, 0.830 and 0.842 respectively. The accuracy of models for the diagnosis of suspect keratoconus and keratoconus was 97.22%, 95.83%, and 98.61%, respectively, and the AUC was 0.951, 0.939, and 0.988 respectively.CONCLUSION: For corneas ≤11.1 mm in diameter, the data model established by CNN+Transformer has a high accuracy rate for classifying keratoconus, which provides real and effective guidance for early screening.

Change in corneal endothelial cell density and morphology in different stages of keratoconus / 中华实验眼科杂志

Objective:To assess the changes in corneal endothelial cell density (CD) and morphology in patients with different stages of keratoconus.Methods:A cross-sectional study was conducted.One hundred and nineteen patients (199 eyes) with keratoconus who were treated in the Eye Hospital of Shandong First Medical University were included from March 2018 to October 2021.The 199 eyes were classified into stage Ⅰ (111 eyes of 58 cases), stage Ⅱ (41 eyes of 30 cases), stage Ⅲ (47 eyes of 31 cases) keratoconus groups according to the Amsler-Krumeich classification.In the same period, 25 age- and sex-matched healthy subjects (50 eyes) were enrolled as a normal control group.Corneal topography and anterior segment parameters such as keratometry (K), central corneal thickness (CCT), thinnest corneal thickness (TCT), anterior chamber depth (ACD), corneal diameter and corneal volume were obtained by Pentacam 3-dimensional anterior segment imaging and analysis system.The corneal endothelial CD, percentage of hexagonal cells (6A), average cell area (AVE), maximum cell area (MAX), minimum cell area (MIN), cell area standard deviation (SD) and cell area coefficient of variation (CV) in the central area were evaluated by non-contact specular microscopy.The correlation between corneal endothelial CD, morphological parameters and corneal topographic parameters was analyzed by Spearman rank correlation.This study adhered to the Declaration of Helsinki and was approved by the Ethics Committee of Shandong Eye Hospital (No.SDSYKYY201803). All patients were informed of the purpose and methods of the study and written informed consent was obtained before any medical examination.Results:The CD of the normal control group and stage Ⅰ, Ⅱ, Ⅲ keratoconus groups was 2 941(2 809, 3 072), 2 825(2 667, 3 030), 2 747(2 475, 2 903) and 2 370(2 142, 2 525) cells/mm 2, respectively.With the progression of keratoconus, CD decreased gradually, and there was a significant difference in CD among the four groups ( H=94.862, P<0.001). There were significant differences in CV and 6A among the four groups ( H=45.018, 20.421; both at P<0.001). CV was significantly higher in stage Ⅲ keratoconus group than that of the normal control group and stage Ⅰ and Ⅱ keratoconus groups and 6A was significantly lower in stage Ⅲ keratoconus group than that of the normal control group and stage Ⅰ keratoconus group (all at P<0.05). With the progression of keratoconus, MAX, MIN, AVE and SD increased gradually, and there were significant differences in MAX, MIN, AVE and SD among the four groups ( H=37.905, 32.437, 110.182, 72.941; all at P<0.001). MAX and MIN in stage Ⅲ keratoconus group were significantly higher than those in stage Ⅰ keratoconus groups and normal control group (all at P<0.05). AVE and SD in stage Ⅲ keratoconus group were significantly higher than those in normal control group and stage Ⅰ and Ⅱ keratoconus groups (all at P<0.05). In patients with keratoconus, CD was moderately positively correlated with CCT ( rs=0.47, P<0.001) and TCT ( rs=0.53, P<0.001), and was moderately negatively correlated with mean keratometry (Km) ( rs=-0.59, P<0.001).6A was weakly positively correlated with CCT ( rs=0.18, P=0.01) and TCT ( rs=0.22, P=0.002), and was weakly negatively correlated with Km ( rs=-0.32, P<0.001). CV was weakly negatively correlated with CCT ( rs=-0.35, P<0.001) and TCT ( rs=-0.37, P<0.001), and was moderately positively correlated with Km ( rs=0.48, P<0.001). There was no correlation between CD, CV, 6A and ACD, or corneal volume. Conclusions:As the keratoconus progresses, the cornea protrudes and becomes thinner with CD and 6A decreasing while CV increasing.Corneal topographic parameters are related to the density and morphology of corneal endothelial cells.

Comparação entre os resultados do implante de um segmento de arco longo versus dois segmentos de arco tradicional no tratamento de pacientes com ceratocone / Comparison between the results of implanting a long-arch segment versus two standard arch segments for treatment of keratoconus patients

RESUMO Objetivo: Analisar retrospectivamente as alterações na ceratometria e no astigmatismo corneano obtidas após cirurgia de implante de anel intraestromal, comparando o uso de um segmento de arco longo versus o implante de dois segmentos de comprimento de arco tradicional. Métodos: A partir de um estudo transversal, obtivemos os dados de 94 olhos de pacientes diagnosticados com ceratocone, que foram submetidos ao implante de anel corneano. Eles foram divididos em dois grupos, dependendo do tipo de implante recebido: Grupo A, um segmento de arco longo; Grupo B, dois segmentos tradicionais. Todos os segmentos implantados possuíam 250µ de espessura. Os dados do pré-operatório dos dois grupos foram comparados, para garantir que as amostras eram similares (as diferenças encontradas entre os dois grupos não eram estatisticamente significativas). As variáveis analisadas no pré e no pós-operatório foram acuidade visual com correção, ceratometria, astigmatismo corneano e refração. Resultados: A amostra que recebeu apenas um segmento de arco longo (Grupo A) obteve redução da ceratometria média de 4,42D (8,7%) e do astigmatismo corneano de 2,43D (40,4%). Já na amostra dos olhos que receberam dois segmentos de arco tradicional (Grupo B), houve redução média de 2,66D (5,1%) em relação à ceratometria média e redução média de 2,11D (34,8%) em relação ao astigmatismo corneano. A redução obtida na ceratometria média no Grupo A foi maior que a obtida no Grupo B (diferença estatisticamente significativa). A redução obtida no astigmatismo do Grupo A não foi estatisticamente significante, se comparada com o resultado obtido no Grupo B (considerando p≤0,05). Conclusão: Foi demonstrado que o uso de um segmento de arco longo possui maior capacidade de aplanação corneana, se comparado com o uso de dois segmentos com comprimento de arco tradicional. Em relação à redução do astigmatismo, os dois grupos mostraram resultados equivalentes.

ABSTRACT Purpose: To retrospectively analyze the changes in corneal keratometry and astigmatism after intrastromal ring surgery, comparing the use of one long arch segment versus two traditional arc length segments. Methods: A cross-sectional study obtained data from 94 eyes of patients diagnosed with keratoconus that underwent surgical treatment with corneal ring implant. They were divided into two groups according to the type of implant received: one long-arch segment (Group A) or two traditional segments (Group B), both 250 microns thick. Preoperative data from the two groups were compared to ensure that the samples were similar (the differences between the two groups were not statistically significant). The variables (pre and post-operatively) analyzed were: best corrected visual acuity, keratometry, corneal astigmatism and refraction. Results: Group A, which received one long arch segment, showed a Km decrease of 4.42D (8.7%) and a corneal astigmatism reduction of 2.43D (40.4%). Group B, where the eyes acquired two traditional arch segments, showed an average Km decrease of 2.66D (5.1%) and corneal astigmatism reduction of 2.11D (34.8%). The mean keratometry (Km) reduction obtained was statistically significant (p≤0.05) when comparing both groups (A and B). The mean corneal astigmatism reduction was not statistically significant (p≤0.05) when comparing both groups (A and B). Conclusions: One long-arch segment has been demonstrated to have a greater capacity to reduce corneal curvature when compared to the use of two traditional-sized arch segments. No significant differences were found regarding the reduction of corneal astigmatism after comparing the results obtained in both groups.

Unexpectedly high corneal flap thickness and ectasia after mechanical LASIK / Espessura inesperadamente alta do flap corneano e ectasia após LASIK mecânico

ABSTRACT LASIK is a refractive surgical procedure in which a corneal flap is created to expose the corneal stromal bed. Preoperative estimation of corneal flap thickness is necessary to calculate the percentage tissue altered in LASIK, an important quantitative risk factor for ectasia. The objective of this study was to assess flap thickness and calculate percentage tissue altered to check if unexpectedly thicker flaps and higher percentage tissue altered could pose as risk factors of ectasia. Four subjects (eight eyes) were submitted to mechanical LASIK in 2009 and 2010. Pre and postoperative clinical and tomographic data were reviewed. Mean preoperative estimated percentage tissue altered was 39.18±1.31%, which was borderline for increased ectasia risk when considering the limit of 40%. However, when considering the postoperatively measured flap thickness, the actual mean percentage tissue altered turned out to be 45.17 ± 4.13%, which was significantly higher than predicted preoperatively (p=0.002). Unexpectedly higher postoperative percentage tissue altered may be responsible for corneal ectasia after mechanical LASIK.

RESUMO A LASIK é um procedimento cirúrgico refrativo, no qual um retalho corneano é criado para expor o leito estromal corneano. A estimativa pré-operatória da espessura do retalho corneano é necessária para calcular o percentual de tecido alterado no LASIK, um importante fator de risco quantitativo para ectasia. O objetivo deste estudo foi avaliar a espessura do retalho e calcular o percentual de tecido alterado para verificar se retalhos inesperadamente mais espessos e percentuais de tecido alterado mais altos poderiam representar fatores de risco de ectasia. Quatro indivíduos (oito olhos) foram submetidos à LASIK mecânica em 2009 e 2010. Dados clínicos e tomográficos pré e pós-operatórios foram revisados. A média de percentual de tecido alterado pré-operatória estimada foi de 39,18±1,31%, limítrofe para risco aumentado de ectasia quando considerado o limite de 40%. No entanto, ao considerar a espessura do retalho medida no pós-operatório, o percentual de tecido alterado médio real foi de 45,17±4,13%, ou seja, significativamente maior do que o previsto no pré-operatório (p=0,002). O percentual de tecido alterado pós-operatóriao inesperadamente mais alto pode ser responsável pela ectasia da córnea após LASIK mecânico.

Agreement between corneal diameter measurements obtained with an optical biometer and a Placido-based topographer / Acordo de medições do diâmetro da córnea obtidas por um biômetro óptico e um topógrafo com base em Plácido

ABSTRACT Purpose: The purpose of this study was to compare the white-to-white distance measurements of two devices (IOL Master 500 and Atlas corneal topographer) commonly used in clinical practice to determine if they were interchangeable. Providing information on instrument interchangeability could eliminate several unnecessary tests and consequently reduce the economic burden for the patient and society. Methods: In this prospective, comparative case series, the white-to-white distance was measured by independent examiners using the Atlas topographer (Carl Zeiss Meditec) and the IOL Master 500 (Carl Zeiss Meditec). One eye each of 184 patients was tested. Statistical analyses were performed using a paired t-test, Pearson correlation analysis, and Bland-Altman analysis to compare the measurement methods. Results: The mean white-to-white distance measurements with the Atlas topographer and the IOL Master 500 were 12.20 ± 0.44 mm and 12.12 ± 0.41 mm, respectively (p<0.001). The mean white-to-white difference between the two devices was 0.07 mm (95% confidence interval of mean difference: 0.04-0.11 mm). The Pearson correlation coefficient between the two devices was 0.85 (p<0.0001). The 95% limits of agreement between the two devices were -0.38 mm to 0.53 mm. Conclusions: The Atlas topographer and IOL Master 500 can be used interchangeably with respect to white-to-white distance measurements, as the range of differences is unlikely to affect clinical practice and decision making.

RESUMO Objetivo: O objetivo deste estudo é comparar as medições de diâmetro corneano de dois dispositivos normalmente utilizados na prática clínica (IOL Master 500 e Atlas topógrafo corneal) para ver se são permutáveis. O fornecimento de informações sobre a permutabilidade de instrumentos poderia eliminar vários testes desnecessários e, consequentemente, reduzir a carga econômica para o paciente e para a sociedade. Métodos: Nesta série de casos prospectivos e comparativos, a distância do diâmetro corneano foi medida por examinadores independentes utilizando o Topógrafo Atlas (Carl Zeiss Meditec) e o IOL Master 500 (Carl Zeiss Meditec), em um olho de 184 pacientes. A análise estatística foi realizada utilizando o teste t pareado, a correlação Pearson e a análise Bland-Altman para comparar os métodos de medição. Resultados: As medições médias da distância do diâmetro corneano com o topógrafo Atlas e o IOL Master 500 foram de 12,20 ± 0,44 mm e 12,12 ± 0,41 mm, respectivamente (p<0,001). A diferença média de WTW entre os dois dispositivos foi de 0,07 mm (intervalo de confiança de 95% da diferença média: 0,04 - 0,11 mm). O coeficiente de correlação Pearson entre os dois dispositivos foi de 0,85, p<0,0001. Os limites de concordância de 95% entre os dois dispositivos foram de -0,38 mm a 0,53 mm. Conclusões: O Atlas topographer e o IOL Master 500 podem ser utilizados permutavelmente em relação à medição do diâmetro corneano, uma vez que a gama de diferenças encontradas é pouco susceptível de afetar a prática clínica e a tomada de decisões.

Efficacy of epithelial-off accelerated corneal cross-linking in the treatment of advanced keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the efficacy of epithelial-off accelerated corneal cross-linking(CXL)in the treatment of advanced keratoconus.METHODS: A retrospective study was performed on data collected from 32 patients(43 eyes)with advanced keratoconus who underwent epithelial-off accelerated CXL at Ningxia Eye Hospital from April 2020 to December 2021. Slit-lamp, intraocular pressure, uncorrected visual acuity(UCVA), corrected visual acuity, specular microscope, Pentacam and Corvis ST were tested before and at 1, 3 and 6mo after surgery. Preoperative and postoperative corneal condition, UCVA, best corrected visual acuity(BCVA)and the values of corneal endothelial, maximum keratometry(Kmax), thinnest corneal thickness(TCT), anterior and posterior surfaces of the cornea K1, K2, biomechanically corrected intraocular pressure(bIOP), applanation time 1(A1T), applanation length 1(A1L), applanation velocity 1(A1V), applanation time 2(A2T), applanation length 2(A2L), applanation velocity 2(A2V), highest concavity deformation amplitude(HCDA), radius at highest curvature(HCR), highest concavity peak distance(HCPD)and stiffness parameter at first applanation(SP-A1)were recorded.RESULTS: There were differences between UCVA(LogMAR; 1.06±0.49, 0.78±0.39)and BCVA(LogMAR; 0.48±0.34, 0.38±0.29)before and at 6mo after surgery(P&#x003C;0.05), but there were no differences in corneal endothelial cells(2917.39±288.38 vs. 2959.19±336.27 cells/mm2, P=0.477). There were differences among Kmax, TCT, anterior surface K1 and K2 and posterior surface K1 before and after surgery(P&#x003C;0.05), and all increased at 1mo after surgery then returned to preoperative level at 3mo after surgery, while there was no difference in the posterior K2. Furthermore, there were statistical significance in A1T, HCPD and SP-A1 before and after surgery(P&#x003C;0.05), while there were no statistical significance in A1L, A1V,A2T, A2L, A2V, HCDA, HCR and bIOP(P&#x003E;0.05).CONCLUSION: Epithelial-off accelerated CXL can prevent the progression of keratoconus within half year after surgery, and it has certain safety.

Evaluation of meibomian gland morphology and anterior segment parameters by Sirius topography systems in polycystic ovary syndrome

Purpose: To compare findings in specular microscopy, corneal topography, and noncontact meibography in polycystic ovary syndrome (PCOS) patients with healthy controls. Methods: A total of 40 women with PCOS and 32 healthy controls were enrolled in the study. Schirmer’s test, Ocular Surface Disease Index (OSDI), noninvasive tear break-up time (NITBUT), the mean keratometry (Km), maximum keratometry (Kmax), central (CCT), thinnest (TCT) and apical (ACT) corneal thicknesses, meibomian gland (MG) loss, meiboscores, morphology of MGs, endothelial cell density (ECD), coefficient of variation (CV), and percentage of hexagonal cells (PHEX) were analyzed. Correlations between anti-Mullerian hormone (AMH) and sex hormones and the findings of PCOS patients were evaluated. Results: Mean OSDI score, intraocular pressure, Km and Kmax values, the mean MG loss of upper and lower eyelids, lower eyelid meiboscore, and degree of morphological abnormalities of MGs were higher in cases with PCOS than healthy controls. There were no significant differences between groups in Schirmer results, first and average NITBUT, mean values of TCT, ACT, CCT, ECD, CV, and PHEX (P > 0.05, for all). There were correlations between plasma AMH level and Kmax, back Km and PHEX, and between estradiol (E2) and PHEX; there were negative correlations between E2 and total MG loss and CV and between total testosterone and ACT. Conclusion: Loss and morphological deterioration of the MGs are observed in PCOS patients, even if the tear parameters are not impaired yet. In eyes with PCOS, keratometry values become steeper in proportion to AMH levels. The PCOS patients should be followed carefully for the development of corneal ectasia.

Development of an application for providing corneal topography reports based on artificial intelligence / Criação de aplicativo para confecção de laudos de topografia corneana baseado na inteligência artificial

ABSTRACT Purpose: To develop an application (TopEye) in the iOS platform for mobile devices to allow the capture and interpretation of color maps generated by corneal topographers using artificial intelligence. Methods: In the execution, follow-up, and assessment of the project, we used the Scrum methodology and interactive and incremental development process for the project management and agile software development. The ge nerated diagnostic pattern bank consists of 1,172 examples of corneal topography, divided into 275 spherical, 302 symmetrical, 295 asymmetrical, and 300 irregular patterns (keratoconus). For the development of the artificial intelligence of the application, network training was established with 240 images of each pattern type, with a total of 960 patterns (81.91%). The remaining 212 images (18.09%) were used to test the application and will be used for the results. The process is semi-automatic, so the topographic image is captured with a smartphone, the examiner performs the contour of the corneal relief manually, and then the neural network performs the diagnosis. Results: The application diagnosed 201 cases (94.81%) correctly. In 212 images, the algorithm missed the classification of 11 cases (5.19%). The major error that occurred was in distinguishing between symmetrical and asymmetrical classes. In keratoconus screening, the application reached 95.00% sensitivity and 98.68% specificity. Conclusion: The work resulted in obtaining an efficient application to capture topographic images using a smartphone camera and their interpretations through applied artificial intelligence.

RESUMO Objetivo: Desenvolver um aplicativo (TopEye) na plataforma iOS para dispositivos móveis que possibilite a captação e interpretação do mapa de cores gerados por qualquer topógrafo corneano através da inteligência artificial (IA). Metodos: A execução, acompanhamento e avaliação do projeto foi utilizada a metodologia Scrum, processo de desenvolvimento interativo e incremental para gerenciamento de projetos e desenvolvimento ágil de software. O banco de padrões de diagnóstico gerado consiste em 1172 exemplos, divididos em: 275 padrões esféricos, 302 regulares simétricos, 295 regulares assimétricos e 300 irregulares (ceratocone). Para o desenvolvimento da inteligência artificial do aplicativo, foi estabelecido o treinamento da rede com 240 imagens de cada tipo de padrão, totalizando 960 (81,91%) padrões. O restante das imagens, 212 (18,09%), foram utilizadas para testar o aplicativo e usadas para gerar os resultados. O processo é semiautomático, assim a captação da imagem topográfica é realizada com smartphone, o examinador realiza o contorno do relevo corneano manualmente para em seguida a rede neural realizar o diagnóstico. Resultados: O aplicativo diagnosticou 201 (94,81%) imagens corretamente. De um total de 212 imagens, o algoritmo errou a classificação de apenas 11 (5,19%). A principal ocorrência de erro foi na distinção das classes simétrica e assimétrica. No rastreio do ceratocone o aplicativo alcançou 95,00% de sensibilidade e 98,68% especificidade. Conclusão: O trabalho resultou na obtenção de um aplicativo eficiente na captura da imagem topográfica pela câmera do smartphone e na interpretação da mesma através da inteligência artificial aplicada.

Assessment of the postoperative effect of corneal cross-linking on keratoconus using the ABCD grading system

Purpose: To monitor the changes in the ABCD grading system during a one?year follow?up after a corneal cross?linking (CXL) procedure. Methods: This prospective study included 30 eyes of 25 patients with keratoconus, who received the CXL treatment. The patients with a history of ocular trauma or surgery and other corneal pathology were excluded from the study. The patients were examined at the baseline visit and followed up at 3, 6, and 12 months after the CXL. All the patients underwent a standard CXL procedure with visual acuity and Scheimpflug tomography testing at each visit. The corneal parameters and ABCD grading were monitored throughout the follow?up period. Results: There were no significant changes of parameter A and anterior radius curvature (ARC) in the ABCD grading system. Parameters B and D showed progression postoperatively, with an improvement of parameter D on the final visit. Parameter C showed a statistically significant increase at all three post?CXL visits, but a constant gradual decrease in the value over time. Conclusion: The ABCD grading system can be very useful in monitoring the progression of keratoconus (KC), but it can also help in monitoring the efficacy of corneal cross?linking. The anterior surface parameters in the ABCD grading system did not show progression in the post?CXL period, and parameters C and D showed improvement and stability a year after the procedure.

Correlation among corneal densitometry, corneal topographic, and biomechanical properties in keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To investigate the correlation among corneal densitometry, corneal topographic parameters, and corneal biomechanical properties in keratoconus.METHODS: Retrospective case study. A total of 70 eyes of 48 keratoconus patients were enrolled in this study. Corneal topography were measured using Pentacam, inclding the flat keratometry of anterior cornea(K1), the steep keratometry of anterior cornea(K2), the mean keratometry of anterior cornea(Km), the maximum keratometry of anterior cornea(Kmax), anterior corneal elevation(ACE), posterior corneal elevation(PCE), thinnest corneal thickness(TCT), and the distance from cone to apex(DCA). Corneal optical density of different corneal layers and zones were measured with the Scheimpflug-based Pentacam corneal densitometry module. Corneal biomechanical properties were measured using CorVis ST, inclding time of the first applanation(AT1), length of the first applanation(AL1), velocity of the first applanation(V1), time of the second applanation(AT2), length of the second applanation(AL2), velocity of the second applanation(V2), the highest concavity time(HCT), the highest concavity deformation amplitude(HCDA), the highest concavity radius(HCR), the highest concavity peak distance(HCPD), stiffness parameter applanation 1(SPA1), Ambrósio's relational thickness horizontal(ARTh).RESULTS: Correlation between corneal densitometry and topographic parameters: The corneal densitometry values of the anterior ≤2mm layer correlated with the K1, K2, Km and Kmax values positively(<i>r</i>=0.291, 0.315, 0.315, 0.387; <i>P</i>=0.015, 0.008, 0.008, 0.001). The corneal densitometry values of the anterior ≤2mm, anterior >2 and ≤6mm, total ≤2mm, total >2 and ≤6mm, and posterior >2 and ≤6mm layers correlated with the anterior corneal elevation positively(<i>r</i>=0.465, 0.302, 0.317, 0.291, 0.335; <i>P</i><0.01, <i>P</i>=0.011, 0.008, 0.014, 0.005), and also with the posterior corneal elevation(<i>r</i>=0.565, 0.369, 0.348, 0.306, 0.284; <i>P</i><0.01, <i>P</i>=0.002, 0.003, 0.010, 0.017). Correlation between corneal densitometry and biomechanical properties: the corneal densitometry values of all ≤2mm, central >2 and≤6mm, posterior >2 and ≤6mm, and total >2 and ≤6mm layers all correlated with AL1 negatively(<i>r</i>= -0.284, -0.290, -0.245, -0.326, -0.282, -0.395, -0.310; <i>P</i>=0.017, 0.015, 0.041, 0.006, 0.018, 0.001, 0.009). The corneal densitometry values of central ≤2mm, central >2 and ≤6mm, and posterior >2 and ≤6mm layers all correlated with AL2 negatively(<i>r</i>= -0.246, -0.256, -0.256; <i>P</i> =0.041, 0.032, 0.032). The corneal densitometry values of anterior ≤2mm layer correlated with HCR negatively(<i>r</i>= -0.308, <i>P</i>=0.010). The corneal densitometry values of central ≤2mm, posterior ≤2mm, and certral >2 and ≤6mm layers all correlated with HCT negatively(<i>r</i>= -0.292, -0.340, -0.262; <i>P</i>=0.014, 0.004, 0.028). The corneal densitometry values of anterior ≤2mm, total ≤2mm, and posterior >2 and ≤6mm layers all correlated with ARTh negatively(<i>r</i>= -0.430, -0.293, -0.319; <i>P</i><0.01, <i>P</i> = 0.014, 0.007).CONCLUSION: The corneal densitometry values correlated with the severity of keratoconus and the biomechanical properties, and may became a potential diagnostic index of keratoconus.

Research progress on the diagnostic techniques of early keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

@#Diagnosis of early keratoconus(KC)contributes to identifying potential patients before typical clinical symptoms. It also contributes to timely intervention of the progress of disease and improvement of long-term prognosis. Hence, it is crucial to prevent iatrogenic corneal ectasia and reduce the burden of keratoplasty. There are diverse kinds of early KC diagnosis techniques, including corneal topography, corneal aberrations, epithelial and corneal thickness measurement, corneal confocal microscopy, corneal biomechanics, and genetic examination. Since it is often difficult to ensure sufficient sensitivity and specificity with single technique, multiple techniques are beneficial to evaluate the cornea comprehensively, which may become the development tendency of early KC diagnosis in the future.

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.

Comparison of corneal refractive power and astigmatism measured by CASIA2, IOLMaster 700 and Pentacam in cataract patients / 中华实验眼科杂志

Objective:To compare the difference and consistency of anterior corneal surface and total corneal refractive power and astigmatism measured by CASIA2, IOLMaster 700 and Pentacam in patients with age-related cataract.Methods:A diagnostic test was conducted.Two-hundred patients (200 eyes) with age-related cataract were enrolled in Tianjin Medical University Eye Hospital from March to April 2021.The steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), degree and axis of astigmatism of the anterior and the total corneal surface of patients were measured by CASIA2, IOLMaster 700 and Pentacam, respectively.The astigmatism was transformed into J0 and J45 by Fourier transform formula.The differences and correlation of the measurements obtained with the three instruments were analyzed by one-way repeated measures analysis of variance and Pearson correlation analysis.The consistency was evaluated by Bland-Altman test.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Tianjin Medical University Eye Hospital (No.2021KY-07).Results:There were statistically significant differences in anterior corneal surface Kf and J0 measured by the three instruments ( F=18.563, 16.172; both at P=0.001). The Kf measured by CASIA2 was significantly higher than that measured by IOLMaster 700, and the J0 measured by IOLMaster 700 was significantly higher than that measured by Pentacam (both at P<0.05). There were statistically significant differences in total corneal Ks, Kf, Km and J0 measured by the three instruments, which from IOLMaster 700 were the largest, followed by CASIA2, then Pentacam ( F=1 300.447, 1 274.117, 1 609.713, 10.372; all at P=0.001). Pearson correlation analysis showed that the corneal refractive power measured by the three instruments was highly correlated (all at r>0.935, P<0.01), and the correlation of astigmatism values was weaker than the corneal refractive power ( r=0.623-0.908, all at P<0.01). Bland-Altman analysis showed that the three instruments had good consistency in measuring the anterior corneal surface refractive power, anterior corneal surface astigmatism and total corneal astigmatism, which were clinically acceptable, while the consistency of total corneal refractive power measurement was poor.The difference in measuring total corneal refractive power was large between IOLMaster 700 and Pentacam, and relatively small between CASIA2 and Pentacam. Conclusions:The consistency of CASIA2, IOLMaster 700 and Pentacam is good in measuring the anterior corneal surface refractive power of patients with age-related cataract, which can be substitutable, but poor in measuring the total corneal refractive power.The total corneal refractive power measurement from IOLMaster700 is the largest, the smallest from Pentacam, which is not recommended to be clinically exchangeable.