Correlation of central corneal thickness with optic disc area in patients with primary open angle glaucoma

ABSTRACT

To evaluate the relationship between central corneal thickness [CCT] and optic disc area in patients with primary open angle glaucoma [POAG]. The study was performed on patients with POAG who were being followed at Johns Hopkins Hospital. All patients underwent thorough eye examination, optic disc imaging with the Heidelberg Retina Tomograph II [HRT II], and ultrasound corneal pachymetry. Exclusion criteria were prior ocular surgery and low-quality HRT II images [HRT standard deviation> 50]. SAS version 8.1 was used to generate Pearson correlation coefficients [r]. Of 199 eyes of 152 participants, 57 eyes met the inclusion and exclusion criteria of the study. Mean CCT was 530.7 +/- 35.5 microns. Black subjects had thinner corneas [blacks= 520 microns, whites= 546, others= 550, p < 0.05]. White subjects had smaller discs [Whites' mean disc area= 1.84 mm2, blacks= 2.44, others= 2.38 P= 0.0003]. Univariate analysis revealed that CCT is inversely correlated with optic disc area [r = -0.215, P= 0.12, n= 53]. After including all HRT images with standard deviation < 100, a statistically significant correlation was observed among white subjects [r = -0.282, P= 0.02, n=60]. Our findings demonstrate that optic nerve size might have some correlation with central corneal thickness. It may be that the protective effect of thicker corneas is not solely due to mis-measurement of IOP, but may also be an indication of more robust optic nerve head tissue