Purpose
Considering that the corneal transparency is maintained by the minimum quantity of the endothelial cell density between 700 and 400 cells.sq.mm, this study intent to know the longevity of the corneal transparency in eyes after they have been submitted to drainage device (DD) implant.
Methods
Retrospective study of the 12 eyes with glaucoma with difficult clinical control submitted to DD in the anterior chamber. The endothelial examinations at the central area were done with contact specular microscopy Bio-Optics LSM 2000 and Bambi 2500 software, with a sample error smaller than 5%. Their reliability indexes were calculated by Cells Analyzer Software - Corneal Endothelial Statistical Lab (Technicall, Brazil). The methodology to calculates the the corneal transparency longevity is follow described. Considering the Endothelial Cell Density (ECD) results given by the specular microscopy (SM) examinations for each clinical case during the follow-up, the linear regression equation and model were defined and it was calculated. The period of the time to starts the corneal decompensation after DD implant for each clinical case was determined based on an ECD of 700 cells.sq.mm (T700), using the linear regression formula. In the same way, it was possible to define the period of time to finish the corneal decompensation, when the ECD go to 400 cells.sq.mm (T400) and the mean time to starts the corneal decompensation. Moreover, the range of the period of the corneal decompensation was calculated: T400 minus T700, in months and years. The GraphPad QuickCalcs were used to calculate the linear regression model and equation and Microsoft Excel 2010 to calculate the descriptive data.
Results
The mean age were 61 years old. The size of the endothelial samples were: Minimum SM per-patient was 3, the Maximum SM was 10, and the mean was 6. The results of the ECD , T700 and T400 were reported at the Table 1. The mean time to starts the corneal decompensation was 91,5 months or 7,6 years. The range of the period of the corneal decompensation was 35 months or 2.9 years.
Conclusions
This is the first study to demonstrate the period of time when start and finish the corneal decompensation, as the range time for that, after DD implant. This study was conducted only with endothelial examinations with sample error smaller than 5%.
Keywords: 481 cornea: endothelium