Purpose
To study how drusen volume and retinal pigment epithelium (RPE) abnormal thinning (RAT) on spectral domain optical coherence tomography (SDOCT) are associated with visual function as assessed by best corrected visual acuity (BCVA) and microperimetry retinal sensitivity (MPRS).
Methods
SDOCT results were compared with BCVA and macular pattern of microperimetry (CenterVue, Inc, San Jose, CA) in patients with various degrees of age-related macular degeneration (AMD). After semi-automated SDOCT segmentation of the RPE-drusen complex (RPEDC), macular volumes for drusen and RAT were calculated from a SDOCT database of 115 healthy aged eyes1. The area of evaluation was a 2.5mm radius centered on the fovea. For general macular MPRS analysis, a median sensitivity score (MSS) was calculated for all 45 eyes of 42 subjects with MPRS. In a subgroup of 18 eyes (18 subjects) that each had an identical MPRS grid pattern, MPRS from each pattern site was paired with SDOCT volume within a 0.5o radius centered at that site. Volumes were correlated with BCVA by Spearman rank correlation (ρ), and with MPRS score by Kruskal-Wallis analysis.<br /> <br /> 1. Farsiu S et al. Quantitative Classification of Eyes with & without Intermediate AMD Using OCT. Ophthalmol. 2014
Results
In 53 eyes without neovascular AMD or geographic atrophy, with a BCVA score and with good quality SDOCT volume, mean (±standard deviation) drusen volume was 0.020±0.030 mm3, and the mean RAT volume was 3.48×10-5±7.8×10-5 mm3. Mean BCVA score was 74.34±14.65. BCVA was worse with an increase in drusen volume (p=0.0001).<br /> <br /> For the 45 eyes with MAIA microperimetry, the mean MSS was 25.76±2.72 dB. Mean drusen volume was 0.021±0.036 mm3 and the mean RAT volume was 4.93×10-5±11.29×10-5 mm3. MSS did not correlate with overall drusen volume (p=0.45).<br /> <br /> In the sub-group of 18 eyes that used the identical MAIA grid pattern and that could be directly mapped and compared with OCT results, better localized MPRS scores correlated with decreasing drusen volume (p<0.0001) at the MPRS sites.
Conclusions
SDOCT measurements of RPEDC and drusen volumes correlated with BCVA. In addition, localized MPRS correlates with the underlying SDOCT drusen volume, while this association is lost when retinal sensitivity across all of the macular sites is compared to general macular volumes.