Changes in Retinal Blood Flow are Strongly Correlated to Changes in Optic Nerve Head Morphology in Patients of African Descent

Abstract

Purpose: To examine the relationship between changes in retinal blood flow and changes in optic nerve head (ONH) morphology in open-angle glaucoma (OAG) patients of African descent (AD) and European descent (ED) over three years.

Methods: 68 patients with OAG (17 AD; 51 ED) were assessed for retinal blood flow using confocoal scanning laser Doppler and ONH morphology using Heidelberg retinal tomography and optical coherence tomography. Total (mean) retinal capillary blood flow was divided into superior and inferior temporal areas and mean retinal flow for each area was determined. Pearson correlations were calculated to evaluate the associations between measurements at baseline and between the changes in measurements between baseline and 3 years with p<0.05 considered statistically significant.

Results: In OAG patients of AD, change in superior mean retinal blood flow was strongly, negatively and significantly correlated with change in cup/disc (C/D) area ratio (r=-0.78, p=0.020) and cup area (r=-0.75, p=0.0283) and strongly and positively correlated with rim area (r=0.74, p=0.0328) and vertical integrated rim area (r=0.86, p=0.0241) over three years. In OAG patients of ED, these correlations were weak and did not reach statistical significance (r=-0.19, p=0.2529; r=-0.17, p=0.2876; r=0.20, p=0.2086; r=-0.05, p=0.7804). The difference in strength of correlations between AD and ED groups was also statistically significant for each relationship (p<0.0052; p<0.0083; p<0.0143; p<0.0001). In OAG patients of AD, change in inferior mean retinal blood flow was also strongly, negatively and significantly correlated with change in C/D area ratio (r=-0.88, p=0.0156) and linear C/D ratio (r=-0.86, p=0.0265) over three years. In OAG patients of ED, these correlations were weak and did not reach statistical significance (r=-0.06, p=0.6923; r=-0.05, p=0.7584). Similar to superior mean blood flow, the differences in each correlation comparison between AD and ED groups was statistically significant (p<0.0001; p<0.0001).

Conclusions: In OAG patients of AD, changes in retinal blood flow were strongly correlated with glaucomatous ONH morphological changes after 3 years. OAG patients of ED had weak correlations, suggesting OAG patients of AD may have a stronger vascular component involved in their glaucoma pathology compared to OAG patients of ED.

Keywords: 436 blood supply • 627 optic disc • 688 retina