Relationship between Central Corneal Thickness and Inter-eye Disease Severity in Primary Angle Closure Glaucoma.

Abstract

Precis: Inter-ocular comparison of primary angle closure glaucoma subjects with asymmetrical and symmetrical visual field loss, revealed significantly thinner central corneal thickness and higher presenting intraocular pressure in the worse eye of the asymmetrical group.

Purpose: To compare the inter-ocular clinical and biometric parameters of primary angle-closure glaucoma (PACG) with asymmetrical and symmetrical visual-field loss at presentation.

Patient and methods: Retrospective study in which the following clinical data were extracted: presenting intraocular pressure (IOP), gonioscopy, visual-field mean deviation (MD), central corneal thickness (CCT), anterior chamber depth (ACD) and axial length (AL). Asymmetrical PACG was defined as the inter-eye visual-field MD difference >6 dB, symmetrical PACG <3 dB, and those with inter-eye difference between 3-6 dB were excluded. Linear mixed effects model was used to adjust for the interdependence of the right and left eyes.

Results: Of 243 PACG subjects, 122 (50.3%) presented with asymmetrical, and 69 (28.4%) with symmetrical disease. The worse eyes in subjects with asymmetrical PACG had significantly higher presenting IOP (P<0.001), narrower angles (P<0.001), more myopic refraction (P<0.001) and thinner CCT (529.2±36.1 μm vs. 535.8±38.5 μm; P<0.001) compared to the fellow eyes; but no inter-eye differences were observed for AL (P=0.93) and ACD (P=0.53). In symmetric PACG, no significant inter-eye differences were observed for CCT (532.3±33.1 vs. 533.1±34.6 μm, P=0.67), AL (P=0.85) and ACD (P=0.18), but the relatively worse eye had higher presenting IOP (P=0.003). In the stepwise multiple linear regression analysis in the asymmetrical group, CCT was the only significant variable (P=0.006), explaining 12% of the variability of the visual-field MD of the worse eye.

Conclusions: In asymmetrical PACG, worse eyes have thinner CCT and higher presenting IOP. Difference in CCT could either be inherent or acquired, and more tests would be needed to tease that out.