Rapid Retinal Nerve Fiber Layer Thinning in the Unaffected Contralateral Eyes of Patients with Unilateral Normal-Tension Glaucoma: A Retrospective Observational Study.

Purpose: To observe the rate of progressive retinal nerve fiber layer (RNFL) thinning in the unaffected eyes of patients with unilateral normal-tension glaucoma (NTG), in comparison with that of healthy subjects, and to identify the factors associated with progressive RNFL thinning.

Design: Retrospective, longitudinal, observational study.

Participants: Ninety-five patients with unilateral NTG and 61 healthy controls.

Methods: This study included unilateral NTG and healthy control subjects who were followed up for longer than 4 years and in whom at least 5 reliable retinal nerve fiber layer thickness (RNFLT) measurements were performed using OCT. Factors associated with the rate of thinning of the unaffected eyes of unilateral patients with NTG were identified using regression analysis.

Main Outcome Measures: The rate of progressive RNFL thinning and the associated factors.

Results: Retinal nerve fiber layer thickness decreased significantly in both the unaffected eyes of unilateral patients with NTG and the healthy eyes (both P < 0.001). The RNFL thinning was significantly faster in the unaffected eyes of unilateral patients with NTG than in the healthy eyes (P < 0.001), specifically in the temporal-inferior (TI) sector (P = 0.003). Factors associated with faster RNFL thinning in the unaffected eyes of unilateral patients with NTG were thicker baseline RNFL of the unaffected eyes (P = 0.002) and a worse visual field (VF) mean deviation (MD) in the NTG eyes (P = 0.040). In the healthy controls, the rate of RNFL thinning in the contralateral eyes was the only factor associated with faster thinning (P = 0.007).

Conclusions: The unaffected eyes of unilateral patients with NTG showed faster RNFL thinning than healthy control eyes, more obviously in the TI sector, and were likely to progress faster when they had a thicker baseline RNFL, and when the NTG eyes had a worse VF MD. In unilateral patients with NTG, initiation of prophylactic treatment could be considered for the unaffected eyes when they are accompanied by a risk of developing glaucoma.

Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.