Abstract
Purpose:
To know the effects of the reliability index, called Sample Error (SE), over the repeatability of the specular microscopy examinations with different number of the counted endothelial cells.
Methods:
Transversal study of 122 endothelial examinations of 61 patients with cataract (63.97 ± 8.15 years old). The Reliability Index called SE was calculated by a specific software (Cells Analyzer (CA), Technicall, Brazil) developed to specular microscopy and confocal microscopy. The Reliability Index of 95% and cut-off Sample Error of 5% were used). Each examination of Konan non-contact NONCON ROBO® SP-8000 Specular Microscope was submitted to standard cell counting, even at the same image, according with the studied group: G40: 40 cells counted, G100: 100 cells counted; G150: 150 cells counted, and GCA: the counted cell number was higher than the determined cell number by the Cells Analyzer software in as many different images as necessary. Reliability index interpretation - 1. The planned SE 5% > the calculated SE: The endothelial examination will be statistically representative of the corneal endothelial cell population; 2. The planned SE 5% < calculated SE: The endothelial examination will not be statistically representative of the corneal endothelial cell population. The SE will be calculated and presented to G40, G100, G150 and GCA. The behavior of the range of the 95% confidence interval to ECD, A, CV and HEX, for each eye, comparing G40-G100, G40-G150, and G40-GCA, will be presented.
Results:
ECD average was 2,395.37±294.34 cells/mm2, A average 423.64±51.09 µm2, CV average 0.40±0.04 and HEX average 54.77±4.19%. The G40 SE was 0.157±0.031, G100 SE was 0.093±0.024, G150 SE was 0.075±0.010, and GCA SE was 0.037±0.005. The increase of the marked cells decreases the SE and decrease the range of confidence interval (right and left eyes respectively): G40-G100 - ECD: 37.00% and 39.79%, A: 38.62% and 43.66%, CV:27.27% and 46.15%, HEX: 36.74% and 40.46%; G40-G150 - ECD: 50.89% and 49.87%, A: 52.05% and 53.33%, CV: 45.45% and 53.84%, HEX: 51.87% and 52.96%; G40-GCA - ECD: 75.79% and 77.39%, A: 75.95% and 77.37%, CV: 72.72% and 76.92%, HEX 75.93% and 76.71%.
Conclusions:
The Reliability Index called Sample Error from the Cells Analyser tutorial method improved close 75% the repeatability of all results of the specular microscopy: ECD, A, CV and HEX.
Keywords: 481 cornea: endothelium •
550 imaging/image analysis: clinical •
459 clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology