RNFL Thickness and Abnormalities of Vision in People with HIV Infection
U.S. investigators examined relationships between contrast sensitivity (CS), color vision and retinal nerve fiber layer (RNFL) among people with human immunodeficiency virus (HIV) infection and evaluated the effect of time since diagnosis of HIV infection on RNFL thickness.
In this noninterventional cross-sectional study, they evaluated 102 eyes of 57 HIV-infected individuals without ocular opportunistic infections. They determined peripapillary RNFL thickness with spectral-domain optical coherence tomography (SD-OCT) in 4 quadrants and measured CS with the Pelli-Robson technique (expressed as logCS). Additionally, they measured color vision with the Lanthony desaturated 15-hue technique (expressed as color confusion index [C-index], with higher scores indicating worse color vision) and assessed correlations between values using Spearman correlation coefficients.
According to the investigators, median RNFL thickness (average of 4 quadrants) was 102.9 µm (range, 75.0–134.7 µm) and median logCS was 1.90 (range, 1.250–1.95). The study investigators also reported that median C-index was 1.58 (range, 0.960–4.07) and that temporal RNFL thickness was correlated with logCS (r = 0.295, p = .003) and C-index (r = 0–0.338, p = .0005). Furthermore, time since diagnosis of HIV infection was shorter for those with thick average RNFL than for those with thin average RNFL (p = .18).
The investigators determined that both worse CS and worse color vision are correlated with thinning of the temporal RNFL, with possible threshold effects. Increased prevalences of abnormal CS and abnormal color vision in this population are therefore likely attributable to neuroretinal compromise. This pattern of structural and functional losses may reflect preferential damage to small-caliber axons in the maculopapillary bundle, possibly associated with mitochondrial dysfunction, providing a potential disease mechanism for HIV-associated “neuroretinal disorder.”