Biomechanical and tomographic findings in Brown-McLean syndrome.

Purpose: Brown-McLean syndrome (BMS) is a clinical condition characterized by peripheral corneal edema with central corneal transparency. This study aims to document the tomographic and biomechanical characteristics of 3 patients with typical BMS features using the Pentacam® AXL and CORVIS ST® (Oculus Optikgeräte GmbH, Wetzlar, Germany). Observations: Three cases of BMS are presented. Case 1 involves a 26-year-old male, Case 2 a 55-year-old male, and Case 3 a 74-year-old male. The patients in Cases 1 and 3 had bilateral BMS, while the patient in Case 2 had BMS in the right eye and aphakic bullous keratopathy in the left eye. All three patients were aphakic following cataract surgery. Notably, Cases 1 and 2 were first-degree relatives (son and father), both with bilateral microspherophakia and resultant bilateral aphakia from pediatric cataract surgery. Tomographic analysis revealed a consistent increase in corneal thickness from the center to the periphery in BMS eyes, marked by an abrupt rise in the corneal thickness spatial profile (CTSP) and percentage thickness increase (PTI) curves from the thinnest point towards the periphery. There was no loss of parallel isopachs, no displacement of the thinnest point of the cornea, and no evidence of focal posterior corneal surface depression, typical signs of generalized corneal edema. Biomechanically, BMS eyes exhibited relatively normal corneal stiffness, integrated radius, Ambrósio's relational thickness to the horizontal profile (ARTh), and maximum deformation amplitude ratio at 2mm from the corneal apex (DA ratio). However, the left eye of the patient in Case 2, which had aphakic bullous keratopathy, showed altered biomechanical parameters indicative of a softer cornea with loss of rigidity. Conclusions and importance: This case series is the first to evaluate the biomechanical and tomographic features of eyes with BMS. Despite the abrupt rise in CTSP and PTI curves from the thinnest point towards the periphery, the relatively normal central corneal biomechanical indices in these BMS eyes are expected when edema is limited to the periphery. These indices become abnormal when there is progression to central corneal edema with bullous keratopathy.

Myopia Prevalence in Latin American Children and Adolescents: A Systematic Review and Meta-Analysis.

Although myopia is a growing global concern, comprehensive studies on its prevalence among Latin American (LATAM) children and adolescents are still lacking. Thus, we conducted a systematic review and meta-analysis to determine the prevalence of myopia in LATAM children and adolescents aged three to 20. The study conducted a thorough literature search from January 1, 1975, to February 28, 2023, identifying 24 studies on the prevalence of myopia in LATAM that met the inclusion criteria. Quality assessment and standardized data collection were performed. The meta-analysis used a random-effects model due to heterogeneity and calculated prevalence rates. Finally, the analysis of data from 24 eligible studies revealed a myopia prevalence of 8.61% (range 0.80-47.36%, 95% confidence interval (CI): 5.22-13.87%, p < 0.05) among 165,721 LATAM children and adolescents. No significant age-based associations or temporal trends were observed in this study. Studies with non-cycloplegic or objective assessment exhibited a numerically higher, although statistically non-significant, myopia prevalence (10.62%, 95% CI: 4.9-21.6%) compared to studies using cycloplegia (7.17%, 95% CI: 3.40-14.50%). In conclusion, myopia affects approximately one in 11 LATAM children and adolescents. Given the increasing exposure of LATAM youth to known myopia risk factors, such as extensive near-work, online learning, and limited outdoor activities, it is crucial to monitor myopia trends in this region. Further research is imperative to address and prevent myopia in LATAM.

Phaco-Chop versus Divide-and-Conquer in Patients Who Underwent Cataract Surgery: A Systematic Review and Meta-Analysis.

Background: Cataract surgery is one of the most frequently performed eye surgeries worldwide, and among several techniques, phacoemulsification has become the standard of care due to its safety and efficiency. We evaluated the advantages and disadvantages of two phacoemulsification techniques: phaco-chop and divide-and-conquer. Methods: PubMed, Cochrane, Embase, and Web of Science databases were queried for randomized controlled trial (RCT), prospective and retrospective studies that compared the phaco-chop technique over the divide-and-conquer technique and reported the outcomes of (1) Endothelial cell count change (ECC); (2) Ultrasound time (UST); (3) Cumulated dissipated energy (CDE); (4) Surgery time; and (5) Phacoemulsification time (PT). Heterogeneity was examined with I2 statistics. A random-effects model was used for outcomes with high heterogeneity. Results: Nine final studies, (6 prospective RCTs and 3 observational), comprising 837 patients undergoing phacoemulsification. 435 (51.9%) underwent the phaco-chop technique, and 405 (48.1%) underwent divide-and-conquer. Overall, the phaco-chop technique was associated with several advantages: a significant difference in ECC change postoperatively (Mean Difference [MD] -221.67 Cell/mm2; 95% Confidence Interval [CI] -401.68 to -41.66; p < 0.02; I2=73%); a shorter UST (MD -51.16 sec; 95% CI -99.4 to -2.79; p = 0.04; I2=98%); reduced CDE (MD -8.68 units; 95% CI -12.76 to -4.60; p < 0.01; I2=84%); a lower PT (MD -55.09 sec; 95% CI -99.29 to -12.90; p = 0.01; I2=100). There were no significant differences in surgery time (MD -3.86 min; 95% CI -9.55 to 1.83; p = 0.18; I2=99%). Conclusion: The phaco-chop technique proved to cause fewer hazards to the corneal endothelium, with less delivered intraocular ultrasound energy when compared to the divide-and-conquer technique.

Efficacy and Safety of Perfluorohexyloctane in Evaporative Dry Eye Disease Associated With Meibomian Gland Dysfunction: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Meibomian gland dysfunction (MGD) is the primary cause of evaporative dry eye disease (DED), which negatively affects the physical and mental quality of life of patients. We performed a meta-analysis of randomized controlled trials (RCTs) comparing perfluorohexyloctane to placebo for MGD in order to identify the best course of treatment for DED in these patients. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline recommendations and prospectively registered the study in PROSPERO (CRD42023442172). The PubMed, Cochrane, and Embase databases were searched for RCTs comparing perfluorohexyloctane to placebo on patients with DED associated with MGD. The statistical analysis was carried out using the "R" software. The mean difference (MD) with 95% CIs was computed using a random-effects model, and p < 0.05 was regarded as statistically significant. The study included 1,814 patients from four RCTs, of whom 972 (53.5%) received perfluorohexyloctane. Patients treated with perfluorohexyloctane had significantly lower total corneal fluorescein staining (tCFS) score (MD -1.09; 95% CI -1.37 to -0.82; p < 0.001; I2 = 0%), eye distress Visual Analogue Scale (VAS) (MD -9.69; 95% CI -12.01 to -7.36; p < 0.01; I2 = 0%), Ocular Surface Disease Index (OSDI) (MD -5.79; 95% CI -8.22 to -3.36 p < 0.01; I2 = 0%), and Eye Burning/Stinging Score (VAS) (MD, -7.16; 95% CI -9.55 to -4.80 p < 0.01; I2 = 0%). The meta-analysis results indicate that perfluorohexyloctane was effective and safe in treating evaporative dry eye, reducing tCFS, eye discomfort, OSDI, and burning sensation, despite the included studies only assessing short-term effects and excluding certain patient groups.

A Morphometric Study of the Pars Plana of the Ciliary Body in Human Cadaver Eyes.

This study aimed to determine the pars plana length in postmortem human eyes using advanced morphometric techniques and correlate demographics to ocular metrics such as age, sex, ethnicity, and axial length. Between February and July 2005, we conducted a cross-sectional observational study on 46 human cadaver eyes deemed unsuitable for transplant by the SBO Eye Bank. The morphometric analysis was performed on projected images using a surgical microscope and a video-microscopy system with a 20.5:1 correction factor. The pars plana length was measured three times per quadrant, with the final value being the mean of these measurements. Of the 46 eyes collected, 9 were unsuitable for the study due to technical constraints in conducting intraocular measurements. Overall, the average axial length was 25.20 mm. The average pars plana length was 3.8 mm in all quadrants, with no measurements below 2.8 mm or above 4.9 mm. There were no statistically significant variations across quadrants or with age, sex, axial length, or laterality. Accurately defining the pars plana dimensions is crucial for safely accessing the posterior segment of the eye and minimizing complications during intraocular procedures, such as intravitreal injections and vitreoretinal surgeries.

Vertex distance variability of the Vision-S™ 700 refractors in normal population / Variabilidade da distância vértice do refrator Vision-S™ 700 em uma população normal

ABSTRACT Objective: To study vertex-optical distance variation and estimate its impact on manifest refraction. Methods: Prospective study in a private clinic using the Vision-S™ 700 with five forehead positions. Forehead on the third position showed the closest vertex-optical distance of 12mm. Results: Analysis of 52 eyes from 26 patients revealed mean differences in vertex-optical distance of 12.25mm (right eye) and 11.75mm (left eye). A 2mm change in vertex-optical distance resulted in a 0.05D change for a 5D spherical equivalent and 0.20D for a 10D equivalent. Conclusion: Vertex-optical distance varies among patients and is influenced by forehead adjustment. These variations impact refraction accuracy and treatment evaluation. Adjusting the forehead to the third position on the Vision-S™ 700 is recommended.

RESUMO Objetivo: Estudar a variação da distância vértice-óptico, de acordo com o ajuste da testa, e estimar seu impacto na refração manifesta. Métodos: Estudo prospectivo realizado em clínica privada. A refração foi realizada utilizando cinco posições preestabelecidas com o Vision-Sa 700. A testa disposta na terceira posição apresentou distância vértice do refrator mais próxima de 12mm. Resultados: Foram analisados 52 olhos de 26 pacientes. A diferença média da distância vértice do refrator no olho direito foi de 12,25mm (variação de 11,50mm) e, no olho esquerdo, 11,75mm (variação de 12,00mm). O impacto foi de 2mm na distância vértice do refrator, fomentando em uma mudança de 0,05D para um equivalente esférico de 5D e 0,20D para um equivalente de 10D. Conclusão: A distância vértice do refrator varia entre pacientes, estando relacionada ao ajuste da testa. As variações afetam a precisão da refração, impactando no ajuste dos óculos, das lentes de contato e na avaliação pós-operatória de cirurgia refrativa. Sugerimos ajustar a posição da testa para terceira posição no Vision-S™ 700, se a distância vértice do refrator não for medida em todos os pacientes.