Central corneal thickness and intraocular pressure measures in human corneas with endothelial guttata: an observational quality control study

Purpose:  The aim of the present study was to assess central corneal thickness (CCT) and intraocular pressure (IOP) in eyes where the corneas were affected by different degrees of severity of endothelial pseudo-guttata or guttata. Methods:  In a prospective, case series observational study, non-contact tonometry and non-contact specular microscopy (NCSM) with pachymetry for central corneal thickness measures were undertaken as routine procedures on predominantly older patients without a history of corneal problems or contact lens wear. For those showing any signs of corneal endothelial abnormalities, images of the central cornea endothelium were further processed to measure the area (as a percentage) occupied by the guttata. Results:  Abnormal endothelial images were obtained from 43 patients (seven with bilateral changes) with an average age of 67.5 years. Between 1.5 and 54.9 per cent of the endothelial images were affected by guttata, which were assigned grade 1 (20 eyes), grade 2 (18 eyes) or grade 3 (11 eyes). When assessed by grade, the central corneal thickness increased and the measured IOP decreased as the guttata became more numerous and confluent. Regression analyses revealed only a weak association between central corneal thickness (p = 0.044, r = 0.149) or the measured IOP (p = 0.090, r = -0.244) and the extent of the guttata (percentage). With the apparently contrasting IOP and central corneal thickness effects, no significant IOP-CCT relationship was noted (p ≥ 0.268, r ≤ 0.160). Conclusions:  Where corneas have mild-to-modest non-dystrophic endothelial guttata, there may be a less predictable effect of corneal thickness on the outcome of tonometry.