Purpose: To investigate, with the use of spectral-domain optical coherence tomography (SD-OCT), microstructural alterations over time in eyes with progressive geographic atrophy (GA) due to age-related macular degeneration.
Methods: Forty-six eyes of 26 patients (median age, 77.9 years [interquartile range (IQR), 71.8-81.0]) with GA without evidence of active or previous neovascular disease at baseline were examined by simultaneous confocal scanning laser ophthalmoscopy (cSLO) and SD-OCT. Serial examinations with alignment of follow-up to baseline scans were performed over a median period of 12.2 months (IQR, 10.2-15.3). Longitudinal SD-OCT variations were evaluated, including quantification of retinal thickness (RT) change and lateral spread of GA (LSGA) at a temporal, nasal, inferior, and superior GA border-section in each eye.
Results: GA-enlargement was characterized by progressive loss of the outer hyperreflective SD-OCT bands and by thinning of the outer nuclear layer with subsequent approach of the outer plexiform layer toward Bruch's membrane. In the perilesional zone, various dynamic changes were recorded, including migration of hyperreflective material and changes in drusen height. At the borders, there was a median RT change of -14.09 microm/y (IQR -26.21 to -7.48 microm/y). The median LSGA was 106.90 microm/y (IQR, 55.44-161.70 microm/y). Both parameters showed only moderate intraocular agreement (RT change: intraclass correlation coefficient [ICC], 0.54; 95% CI, 0.39-0.67; LSGA: ICC, 0.49; 95% CI, 0.34-0.64) and no statistical significant difference for one location (RT change, P = 0.125; LSGA, P = 0.516; likelihood ratio test).
Conclusions: Combined cSLO and SD-OCT imaging provides unprecedented insight into dynamic microstructural changes of GA enlargement that may help to better understand the pathogenesis of the disease. Quantitative progression data indicate local factors may exist that drive progression in junctional areas (ClinicalTrials.gov number, NCT00393692).