Abstract
Purpose::
To study the topographic parameter of the optic nerve head in patients with HIV and normal controls and to determine any correlation between stage of HIV disease and optic nerve head parameter.
Methods::
We used a confocal scanning laser tomograph (HRT3) to examine patients with HIV and normal controls. We looked at 1) the retinal nerve fiber layer (RNFL) parameters and 2) the optic disk parameters. We subgrouped our patients with HIV according to CD4 count nadir. We included 105 eyes of 54 subjects with high CD4 count (group A) and 67 eyes of 36 subjects with low CD4 count (group B, CD4 < 100). Our normal control group (C) was 40 eyes of 20 subjects. We excluded all eyes from our normal control group that had any retinal pathology, myopia over 5 D, had glaucoma or were classified as outside of normal limits according to the Moorfields classification. Contourlines were drawn by superpositioning of the color fundus photograph. An ordinal logistic stepwise regression on CD4 status was performed by global variables to screen the significant variables which were then compared across three groups using Tukey HSD.
Results::
The analysis of the RNFL parameters showed that global mean RNFL thickness and RNFL cross sectional area were significant thinner in groups A (0.228±0.091 and 1.183±0.479) and B (0.234±0.08 and 1.189±0.386) when compared to control (0.263±0.069 and 1.394±0.362). Furthermore, the inferior-temporal subfield showed also a significant reduction in RNFL parameters. We also investigated the structural changes to the optic nerve. No significant increase in cup/disc area ratio or cup depth was observed. However, a significant change in the global cup shape measure was observed between groups B (-0.218±0.066) and C (-0.239±0.06). This observation is consistent with structural change of the cup shape measure in glaucoma.
Conclusions::
We have previously shown that subjects with HIV and low CD4 count experience localized nerve fiber layer loss as determined by OCT, GDx and HRT. We hypothesize that this loss may be caused by tissue damage associated with cotton wool spots. In this study we were investigating the RNFL thickness change and the structural changes to the optic nerve head topography. HRT3 analysis confirms the observation of retinal nerve fiber layer loss and also shows a small effect on the cup shape measure, consistent with NFL loss. The fact that this RNFL and structural change is more pronounced in subjects with low CD4 nadir suggests that HIV disease severity is associated with NFL damage and changes in cupping.
Keywords: AIDS/HIV • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic nerve