Abstract
Abstract: :
Purpose: To identify relationships between central corneal thickness (CCT) and optic disc topography, as determined by scanning laser ophthalmoscopy (SLO), for patients seen in a specialist glaucoma service. Methods: 274 eyes of 145 patients with primary open angle glaucoma (POAG; n=64), normal tension glaucoma (NTG; n=43), ocular hypertension (OH; n=48) and those considered to be suspicious for glaucoma (GS; n=119) underwent ultrasonic pachymetry and SLO (Heidelberg Retina Tomograph; HRT 1). CCT values and optic disc HRT topographical parameters were compared between diagnostic groups and significant correlations between CCT and HRT parameter values identified. Results: Mean CCT values were 527±38µm (NTG), 533±33µm (POAG), 548±37µm (GS) and 565±34µm (OH). As a group the OH eyes had significantly thicker CCT values than eyes with NTG (p<0.0001) or POAG (p<0.0001). In addition, the NTG eyes had significantly thinner CCT values than GS eyes (p<0.007). Multiple HRT parameter differences were identified between the diagnostic groups. Of particular interest, however, was the finding that CCT was inversely correlated with ‘volume below reference’ (r=–0.23, p=0.0001), ‘maximum cup depth’ (r=–0.15, p=0.01) and ‘cup shape measure’ (r=–0.27, p<0.0001). Conclusion: In this cohort of patients, thinner corneas appeared to be associated with larger and deeper optic disc cups, and with increased irregularity of the neuroretinal rim, which are topographic signs regarded to be indicative of glaucomatous optic neuropathy. Thinner corneas may be associated with morphological changes of the optic nerve head (eg a thinner lamina cribrosa) that increase susceptibility to glaucomatous optic neuropathy.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic disc • cornea: basic science