Abstract
Purpose :
Studies of lenses and supplies for intraocular surgeries have in the SM of the corneal endothelium an important marker of aggression or toxicity, as their mitosis is rare and without clinical significance in life. A special case is the long-term follow-up of the endothelium from patients undergoing PK. These cases have low endothelial cellularity characterized by large size, so the number of cells included in a specular microscopy image will be much smaller than if they were normal sized.
Purpose: To know the sampling error of exams with the cells of an image; to know the profile of exams with the necessary number of cells from different images to obtain a sample error < 5%; to know its effects on the endothelial results obtained using Cells Analyzer software reliability indexes - Corneal Endothelial Statistical Lab PAT USA.
Methods :
Cross sectional study of 48 eyes with long time of PK of the Prof. Dr. Fernando Abib Eye Clinic. Contact BioOptics 2500 Corneal SM (BioOptics, USA) to evaluate the endothelial mosaic (EM) at the Donor Disc to calculate endothelial cell density (ECD), cellular area (CA), coefficient of variation (CV) and percentage of hexagonal cells (HEX). The sample size of the SM was calculated using Reliability Index calculated by the Cells Analyzer - Corneal Endothelial Statistical Lab PAT. USA, Technicall, Brazil (95% sample accuracy and 0.05 relative error or sample error). Descriptive data was presented by descriptive statistics.
Results :
All exams with an endothelial image (100%) had a sampling error > 5%. Based on the Reliability Indices used, 44 (91.37%) of the exams had a sample error < 5% and 4 (8.33%) did not due to limitations in the transparency of the examined corneas (Table 1).
Comparing the results of the exams with 1 image with the ones with the necessary number to obtain a sampling error smaller than 5% (10.4 ± 3.5 images), the confidence intervals decreased by 68.18% for ECD, 69.28% for CA, 73.12% for CV and 75.07% for HEX (Tables 1 and 2).
Conclusions :
All exams performed with an endothelial image had a sampling error > 5%, so a single image does not provide results with good reproducibility.
The SM Reliability Indexes demonstrated the need for exams with endothelial samples with around 10 images to obtain a sampling error < 5%, thus the fluctuation of the results decreased from 68 to 75% considering the confidence intervals of ECD, CA, CV and HEX.
This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.