Relationship between asymmetric central corneal thickness and glaucomatous visual field loss within the same patient.

PURPOSE: Considering that thinner central corneal thickness (CCT) has been identified as a significant glaucoma risk factor, this study was designed to determine whether patients with glaucoma with asymmetric CCT demonstrate greater visual field loss in their thinner CCT eye compared with their thicker CCT eye.

METHODS

Patient logs were used to retrospectively identify patients with primary open-angle glaucoma (POAG) and patients with normal-tension glaucoma (NTG) with CCT asymmetry of 10 microm or greater. Severity of glaucoma was determined using Advanced Glaucoma Intervention Study (AGIS) visual field scoring criteria. After statistical analysis was used to compare all thinner CCT eyes vs. corresponding thicker CCT eyes, subjects with worse visual field loss in the thinner CCT eye were compared with subjects with worse visual field loss in the thicker CCT eye. Subanalysis was then completed using only subjects with CCT asymmetry of 15 microm or greater.

RESULTS

In the 52 subjects who met all criteria for study inclusion, mean AGIS score was significantly higher in the thinner CCT eyes compared with the thicker CCT eyes. Subjects with higher AGIS score in their thinner CCT eye outnumbered subjects with higher AGIS score in their thicker CCT eye, with the differences approaching statistical significance in the full sample (p = 0.06) and achieving significance when analysis was limited to subjects with CCT asymmetry of 15 microm or greater (p = 0.001). Multivariate logistic regression analysis identified thinner CCT as the primary risk factor associated with higher AGIS score in subjects with CCT asymmetry of 15 microm or greater.

CONCLUSION

These results correspond to prior reports implicating CCT as an independent risk factor for glaucomatous visual field loss. When significant CCT asymmetry is present in patients with glaucoma, the thinner CCT eye is at greater risk for more advanced visual field loss. The underlying nature of this increased risk is unknown, but further study into structural vulnerabilities associated with thinner CCT seems justified.