Purpose: To evaluate functional changes (retinal sensitivity and fixation characteristics) determined by microperimetry in patients with early and intermediate AMD over 6 years.
Methods: Prospective, longitudinal follow-up (FU) study of 16 patients (29 eyes) with early and intermediate AMD (AREDS 2 and AREDS 3 classification). All eyes underwent: complete ophthalmic examination with best corrected visual acuity (BCVA) determination, color fundus photo (CFP), optical coherence tomography and microperimetry. All CFP were evaluated by two retinal specialists masked to functional data for changes in severity of clinical features over the course of FU.
Results: Of 17 eyes graded as AREDS 2 at baseline, 14 (82.35 %) remained stable, and 3 (18.75 %) progressed to AREDS 3. Of 12 eyes graded as AREDS 3 at baseline, 10 remained stable (83.33 %), and 2 (16.67 %) progressed to AREDS 4. Mean BCVA significantly deteriorated in both AREDS 2 (p = 0.006) and AREDS 3 (p = 0.016), with greater decrease in AREDS 3 (p = 0.01)6. Mean retinal sensitivity (RS) significantly decreased over time in both AREDS 2 (p < 0.0001) and AREDS 3 group (p = 0.002), with greater decrease in AREDS 3 (p = 0.006). The mean number of dense scotomas did not change in AREDS 2 (p = 0.3), but significantly increased in the AREDS 3 group (p = 0.035). Points with decreased RS were located in all but the central point (p < 0.0001 for all), without significant differences in number among rings. In the AREDS 2 group, fixation stability remained unchanged. In the AREDS 3 group, four eyes deteriorated from stable to unstable fixation at FU (p = 0.045).
Conclusion: A significant deterioration in RS is reported in early and intermediate AMD eyes, whereas fixation stability changed only in intermediate AMD (AREDS 3) over long-term follow-up. Microperimetry examination can become a new functional biomarker in early and intermediate AMD patients.
Keywords: Early age-related macular degeneration; Fixation; Intermediate age-related macular degeneration; Microperimetry; OCT; Retinal sensitivity.