Evaluation of Relationships between Retinal Microvascular Parametric Changes and Immune Status in Patients with HIV

Abstract

 

Purpose

 

HIV is associated with microvascular changes that are measurable from retinal photography. We aimed to investigate the relationship between changes in retinal vascular parameters and CD4 counts in HIV patients on highly active anti-retroviral therapy (HAART) over 9 months.

 

Methods

 

This was a prospective longitudinal study of 82 HIV patients on HAART recruited in 2011 from the CDC Singapore. The standard method of monitoring of the immune status of a patient with HIV is with blood CD4 counts. Patient demographics, clinical examination, systemic treatment and blood CD4 levels were recorded. To date, a total of 17 patients completed 9 months follow-up. Retinal photography was taken at both time points and retinal vascular parameters (caliber, fractal dimension, tortuosity and bifurcation) were measured from optic disc-centered retinal photographs by using a semi-automated computer-based program (Singapore I Vessel Assessment, v3.0), following a standardized protocol. Changes in percentage of retinal vascular parameters were calculated as: difference in retinal vascular parameter measurement at 9 months and baseline/ retinal vascular parameter measurement at baseline x100 %. Changes in CD4 counts were calculated as a difference in CD4 counts at 9 months and at baseline.

 

Results

 

The mean CD4 count was 185.3cells/µL (SD±125.9). The mean retinal arteriolar caliber was 137.3µm (SD±16.8) and mean retinal venular caliber was 197.9µm (SD ±19.0). Age and gender adjusted linear regression showed that each 10% increase in retinal arteriolar caliber was associated with a significant increase of 13.6 cells/µl (SD±0.3cells/µL, p<0.001) in CD4 counts after 9 months of HAART. This relationship remained consistent after further adjusting for ethnicity and duration of anti-retroviral therapy (CD4 13.2 cells/µL, SD±0.5 cells/µL; p<0.001). Changes in other retinal vascular parameters (venular caliber, curvature tortuosity, branching angle and fractal dimension) were not associated with changes in CD4 count after 9 months of HAART.

 

Conclusions

 

Longitudinal increment in retinal arteriolar caliber was associated with larger changes in CD4 counts in patients with HIV after 9 months of HAART. This finding suggests that retinal arteriolar caliber might reflect long-term improvement in the immune status of HIV/AIDS patients undergoing HAART.

 

 

Change in retinal arteriolar caliber(%) vs CD4 change(%)

 

Keywords: 415 AIDS/HIV • 550 imaging/image analysis: clinical • 688 retina