Comparison of Central Corneal Thickness Measurements Using Specular Microscope, Optical Biometer and Corneal Topographer

Purpose: To compare the Central Corneal Thickness (CCT) measurements by three different devices in normal eyes. Study Design: Cross sectional observational study. Place and Duration of Study: Dow University of Health Sciences and Dr. Ruth K.M. Pfau Civil Hospital, Karachi, from October 2020 to January 2021. Methods: 80 eyes of healthy subjects aged between 20 to 50 years were included in the study. Patients with corneal pathologies, systemic disease, history of ocular surgery or trauma, high intraocular pressure and high refractive error were excluded. Subjects underwent full ophthalmic examination. Central Corneal Thickness was measured by specular microscope (Shin-Nippon SPM-700; Rexxam Co. Ltd, Takamatsu, Japan), optical biometer (AL-Scan; Nidek, Gamagori, Japan) and corneal topographer (TMS-5; Tomey corporation, Nagoya, Japan). All data entry and analysis was done on SPSS version 23. For correlation among devices, Pearson correlation coefficient was used. Scatter plot was drawn for graphical presentation. Results: 80 eyes of 80 healthy subjects (50 males, 30 females) were recruited in the study by convenient sampling. The mean age was 37.76 ± 8.35 years. Mean Central Corneal Thickness values were 515.57 ± 31.54 µm, 510.21 ± 30.11 µm, 522.03 ± 29.78 µm with specular microscope, optical biometer and corneal topographer respectively. Measurements by these devices strongly correlate with each other using Pearson correlation coefficient (r = 0.927 to 0.966, p ? 0.001). Conclusion: The results of Central Corneal Thickness measurements obtained from these three devices positively correlate with each other so any of these devices can be used for its measurement. Key Words: Central Corneal Thickness (CCT), Specular microscope, Optical biometer, Corneal topographer.

Low-cost, Smartphone-based Specular Imaging and Automated Analysis of the Corneal Endothelium

ABSTRACTPurposeSpecular and confocal microscopes are important tools to monitor the health of the corneal endothelium (CE), but their high costs significantly limit accessibility in low-resource environments. In our study, we developed and validated a low-cost, fully automated method to quantitatively evaluate the CE using smartphone-based specular microscopy.MethodsA OnePlus 7 Pro smartphone attached to a Topcon SL-D701 slit-lamp was used to image normal the central corneal endothelium using the specular reflection technique. Images were automatically processed on-device and endothelial cell density (ECD), percentage of hexagonal cells (HEX), and coefficient of variation (CV) values were determined using our novel image analysis algorithm. The morphometric parameters generated from the images taken by Tomey EM-4000 specular microscope were compared between the testing modalities.ResultsNo significant differences in ECD (2799 ± 156 cells/mm2 vs 2779 ± 166 cells/mm2; p=0.28) and HEX (52 ± 6% vs 53 ± 6%; p=0.50) computed by smartphone-based specular imaging and specular microscope, respectively, were found. A statistically significant difference in CV (34 ± 3% vs 30 ± 3%; p<0.01) was found between the two methods. The concordance achieved between the smartphone-based method and the Tomey specular microscope is very similar to the concordance between two specular microscopes reported in the literature.ConclusionsSmartphone-based specular imaging and automated analysis is a low-cost method to quantitatively evaluate the CE with accuracy comparable to the clinical standard.Translational RelevanceThis tool can be used to screen the CE in low-resource regions and reveal the need for further investigation of suspected corneal endotheliopathies.

Assessment of Corneal Endothelial changes in type II Diabetes Mellitus by Non-Contact Specular Microscope

Introduction Numerous studies were dedicated to explaining the effect of type II diabetes on corneal endothelium. There seemed to be a conflict in the results of the studies, some highlighted that diabetes did not affect the corneal endothelium but rather the corneal thickness. While others disagreed stating that there was damage to the endothelium. The rest cited low endothelial cell density only in poor glycaemic control. This prospective analytical study will extensively investigate the effect of diabetes on the corneal endothelium using non-contact specular microscopy. Aim Prospective analysis of the effect of type II diabetes mellitus on the corneal endothelium performed by specular microscopic examination using KONAN Non-Contact Specular Microscope CC-5000 Cellchek; with regards to cell count, density, size, morphology and comparing them to normal subjects of the same age group. The aim of the study is to completely understand the changes that occur to the corneal endothelium in diabetic patients. Patients and Methods This is a cross-sectional study, in which 30 Diabetic eyes and 30 Control eyes were examined using non-contact specular microscope. Patients were recruited from the Specialized Eye Hospital Kobry El Kobba Military Medical Complex. Results The study included 17 males and 13 females in the non-diabetic control group while in the diabetic group it included 16 males and 14 females. By comparing the demographic data of the two study groups, no significant difference (p &gt; 0.05) was found. The same results were obtained in data regarding the age. Comparing both groups regarding the cell count, density and average cell size showed a highly significant difference (p &lt; 0.05). While comparing the coefficient of variation and the percentage of hexagonal cells in both groups showed a significant difference (p &gt; 0.05). Conclusion Diabetes has been implicated in the morbidity of the corneal endothelium. Our study concluded that it appears that diabetes has a significant impact on the corneal endothelial anatomy, causing endothelial cell loss and a decrease in cell density producing compensatory polymegathism. Triggering a disturbance in the physiological functions of the endothelium when under stress e.g. trauma, surgery or intraocular inflammation. However, under normal physiological conditions we found out that there was no abnormality or impairment in the corneal endothelial functions; in keeping the corneal deturgesence (relatively dehydrated, 70% hydration). Therefore, we concluded from the results that special caution should be taken in diabetic patients to whom any stress is applied on the corneal endothelium so that they do not develop corneal decompensation leading to significant morbidity.