Abstract
Purpose: :
There is evidence to suggest that the alternation of retinal blood flow might play a role in the development of choroidal neovascularisation (CNV) in patients with age–related macular degeneration (AMD) although studies to correlate AMD grade with retinal blood flow have been equivocal.
Methods: :
A database was assembled of patients comparing AMD grade (Rotterdam scale) to psychophysical assessment of protan and deutan colour axes using the Chromatest programme. 13 patients were selected with AMD grades 1 or 2 and colour thresholds better than the mean for that subgroup and 13 patients with AMD grades 3 or 4 and colour thresholds worse than the mean for that subgroup. Computer–assisted grading of retinal vessel calibre (similar to the Wisconsin system) was performed from digital fundal images centered on the disc to determine the average diameter of retinal arterioles and venules and hence an indicator of retinal blood flow. The macula area was cropped to the masked observers.
Results: :
5 patients from the AMD grades 3 or 4 and poor colour vision group had A/V ratios of 0.66 or greater compared to none from the AMD grades 1 or 2 and good colour vision group (Fisher’s exact test, p=0.02).
Conclusions: :
Retinal blood flow is significantly associated with AMD grade if an additional weighting for retinal function such as colour thresholds is also considered.
Keywords: age-related macular degeneration • blood supply • color vision