Relationship between central corneal thickness and inter‐eye disease severity in primary angle closure glaucoma

Abstract

Aims/Purpose: To determine whether subjects with asymmetric primary angle closure glaucoma (PACG) demonstrate greater central corneal thickness (CCT) asymmetry compared to those with symmetrical disease severity.Methods: The following clinical data were retrospectively extracted from the case records of 281 PACG subjects: presenting intraocular pressure (IOP), visual field mean deviation (MD) at presentation, CCT, anterior chamber depth (ACD), and axial length (AL). The eye with the worse visual field MD was considered the worse eye. Asymmetric PACG was defined as the inter‐eye visual field MD difference of greater than 5 dB; and symmetrical PACG disease as an inter‐eye difference of less than 5 dB. Subjects with previous acute primary angle closure were excluded.Results: Based on the definitions, a total of 160 out of 281 PACG subjects (56.9%) presented with asymmetrical disease and 121 (43.1%) with symmetrical disease. Subjects with asymmetric disease had a significantly thinner CCT in the worse eye (529.2 ± 35.2 μm) compared to the fellow eye (535.3 ± 37.2 μm) (p < 0.001), and higher presenting IOP (28.8 ± 12.0 vs 20.1 ± 8.4 mmHg, p < 0.001), but no inter‐eye differences were observed for measurements of AL (p = 0.71) and ACD (p = 0.51) respectively. For patients with symmetric disease, no significant inter‐eye differences were observed for CCT (531.7 ± 31.2 vs 532.9 ± 32.4 μm, p = 0.38), AL (p = 0.30) and ACD (p = 0.31), but the worse eye had significantly higher IOP (22.7 ± 7.9 vs 20.6 ± 6.9 mmHg, p < 0.001). In the asymmetric disease group, 30.6% of subjects had a thinner CCT (≥ 10 μm) in the worse eye compared to 16% of subjects in the symmetric group. There was no correlation between inter‐eye CCT difference and inter‐eye difference of visual field MD (p = 0.17).Conclusions: In PACG subjects with asymmetric disease at presentation, eyes with more severe disease have a thinner CCT and higher presenting IOP. Whether CCT is an independent risk factor for PACG through mechanisms beyond its influence on IOP measurements remains to be established.