Abstract
Purpose::
Advanced age-related macular degeneration (AMD) patients may have glaucomatous-like optic discs with normal IOP. Previous studies that investigated the relation between advanced AMD lesions and optic nerve appearance provided conflicting results. We designed this study to describe and quantify the thickness of the retinal nerve fiber layer (RNFL) using optical coherence tomography (OCT) in patients with advanced AMD.
Methods::
A total of 415 charts of AMD patients were reviewed. From these, 45 subjects with advanced AMD (defined as geographic atrophy or disciform scar) in at least one eye were enrolled. Patients with glaucoma or glaucomatous visual field defects were excluded. The probability of glaucomatous optic nerve damage was scored by clinical evaluation and stereoscopic optic disc photographs. The area of macular involvement was measured in units of disc area. RNFL thickness measurements were performed with the OCT-3, using the RNFL thickness and fast RNFL thickness software. Data analyzed included the average RNFL thickness as well as the thickness in each of the quadrants around the optic disc. The correlation between the area of macular involvement and the RNFL thickness was analyzed. In a sub-group of patients with bilateral advanced AMD, eyes with larger areas of AMD were compared with their fellow eyes with smaller areas of AMD.
Results::
All eyes had advanced AMD lesions that included the central macula. Lesion size ranged from 0.1 to 10 disc area. We found a positive correlation between macular lesion size and RNFL thinning: eyes with larger lesions showed thinner RNFL thickness measurements. This finding was statistically significant for the average RNFL thickness (r=0.76, p=0.01) and also for the upper (r=0.068, p=0.028) and lower (r=0.76, p=0.011) individual quadrants. A similar non-statistically significant trend was found for the medial and temporal quadrants. This finding was even more apparent in larger (> 5 disc area) macular lesions. In patients with bilateral advanced AMD, the eye with the larger macular lesion had thinner RNFL than the fellow eye in all quadrants (p<0.05).
Conclusions::
Extensive AMD lesions correlate with thinner RNFL. Optic atrophy in AMD may be caused by the AMD itself but resemble glaucomatous optic neuropathy. This should be taken into consideration when evaluating patients with AMD for glaucomatous damage.
Keywords: age-related macular degeneration • nerve fiber layer • optic disc