Quantitative corneal neural imaging using in vivo confocal microscopy in cases of congenital corneal anesthesia: A prospective analysis and clinical correlation

PURPOSE: Congenital corneal anesthesia (CCA) is a rare clinical entity that poses a diagnostic dilemma, particularly in the pediatric age group with very little literature on this. Accurate initial diagnosis, evaluation, early identification of risk factors, aggressive systemic workup, and appropriate therapy are paramount to prevent visual loss due to long-term complications of corneal anesthesia. The purpose of the study was to estimate and compare the corneal neural architecture using real time, in vivo confocal microscopy (IVCM) in patients with CCA as against a control population. METHODS: This was a retrospective nonconsecutive, comparative clinical case series in a tertiary hospital in South India from June 2015 to December 2018. METHODS: IVCM was accomplished in cooperative children in whom central cornea was relatively clear. The clearest three to five images from each eye were selected, and the nerves were analyzed for length, thickness, density, dichotomous pattern, and beading. Statistical analysis was done using Origin v7.0 (Origin Lab Corporation, Northampton, MA, USA). RESULTS: In total, 15 eyes of 11 cases and 20 eyes of 10 controls were imaged. Measurements on corneal nerve density showed a significant difference (P = 0.0005), cases having a lower mean (3.85 ± 1.38 mm per mm(2)) compared to the controls (6.74 ± 1.75 mm per mm(2)). Measurements on corneal nerve length (P = 0.28), thickness (P = 0.45), and presence of beading (P = 0.97) and dichotomous pattern (P = 0.07) did not reveal a significant difference between cases and controls. CONCLUSION: There is a strong relationship between the functional loss (absent corneal sensation) and anatomical decrease (reduced subbasal nerve density) of corneal nerves in congenital corneal anaesthesia.