Corneal Volume of the Normal Human Corneas calculated by Pentacam

Abstract

Purpose : The Corneal Endothelial Dysfunction (CED) has acquired importance in recent years, since it has come to be recognized as an indication of endothelial transplantation. CED causes corneal edema, and depending on its cause it may be reversible, such as in cases of acute glaucoma, panuveitis, endothelitis, among others. It may also be classified as reversible, partially reversible or irreversible, depending on the degree of endothelial mosaic injury. The authors recognize endothelial transplantation as the single form of treatment of irreversible CED. The diagnosis and classification of CED should consider the presented symptoms, visual acuity with better optic correction, pachymetric study - preferably serialized by maps and resources obtained by Pentacam or similar device, and the study of the volumetric cornea, also preferably serial. The world literature lacks in determining reference values of normality for corneal volume. The aim of this study is to present values of normal human corneal volume obtained in normal patients.

Methods :
Cross-sectional study with database of the 150 right eyes of the patients submitted to cornea study with Pentacam HR (Germany) at the Cornea Service of the Clinic of Eyes Prof. Dr. Fernando Abib, Curitiba, Brazil. The corneal volume was calculated in a 3mm, 5mm, 7mm, and 10mm diameter zone around the corneal apex. corneal volume (mm³) results are presented the minimum, maximum average, standard deviation, and 95% confidence interval (CI). The results are presented by descriptive statistics. The used software was Microsoft Excel.

Results : The volume of the all studied corneas by zone diameter (Figure 1). The results of the volume by zone diameter Figure 2): Corneal volume at the 3mm zone: range 3 - 4.9mm³, 3.98 ± 0.25mm³ and 95%CI 3.98 ± 0.4 mm³ (3.94 - 4.02); Corneal volume at the 5mm zone: range 9 - 14.2mm³, 11.63 ± 0.69mm³ and 95%CI 11.63 ± 0.11mm³ (11.52 - 11.74); Corneal volume at the 7mm zone: range 20.8 - 30.0mm³, 24.87 ± 1.41mm³ and 95%CI 24.87 ± 0.22mm³ (24.65 - 25.09); Corneal volume at the 10mm zone: range 49.8 - 70.1mm³, 60.13 ± 3.56mm³ and 95%CI 60.13 ± 0.57 mm³ (59.56 - 60.70).

Conclusions :
The normal human corneal volumetric results for the zones of 3mm, 5mm, 7mm, and 10mm can collaborate in the diagnosis of corneal edema, contributing to the classification of Corneal Endothelial Dysfunction.

This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.