Abstract
Purpose: :
HIV patients develop non infectious retinopathy characterized by retinal cotton wool spots and microvascular abnormalities. Retinal cotton wool spots are microinfarctions of the inner retina; ophthalmoscopically these lesions fade however we hypothesized that structural changes should be permanent and possibly visible well after ophthalmoscopic resolution. We hypothesized that simultaneous SLO / Spectral Domain OCT would allow co-localization of the lesions and determine the extent and location of residual damage after ophthalmoscopic resolution of the lesions
Methods: :
19 resolved cotton wool spot lesions in 8 eyes of 7 HIV patients were identified. Using simultaneous SLO and OCT examinations the areas of cotton wool spots were scanned by overlaying the color retinal image over the SLO image and scanning at high resolution in the horizontal plane thru the resolved CWS. Lesions were imaged between 2 and 16 (median 7.84) years after the acute CWS. Each CWS lesion had a control area taken from the same eye within 2 disc diameters of the lesion. The thickness of each of the retinal layers was compared between lesions and control areas using a paired t-test using multitest correction.
Results: :
The largest loss of thickness was seen in the retinal ganglion cell layer with a 43% reduction in thickness. In the inner and middle retinal layers, there was a statistically significant thinning of the retinal nerve fiber layer (NFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL) and the outer plexiform layer (OPL). The median thickness differences ranged from 5 to 7 microns. This difference was highly statistically significant. Another striking finding was the displacement of the outer nuclear layer towards the retinal surface resulting in an apparent (artifactual) increase in thickness of the ONL by over 15 % (median difference of 12 microns).
Conclusions: :
Our data shows for the first time that it may be possible to quantify the burden of HIV retinal disease in terms of retinal destruction. In addition, this will allow quantification of the vision loss structurally in HIV patients. The above study suggests that with ultrahigh resolution and high speed SD OCT, the retina can be mapped and it will be possible to quantify the cumulative damage and location of the damage to the retina in eyes with hypertensive retinopathy, diabetes and HIV disease. It is likely that in eyes that have had multiple such lesions, vision loss occurs and is manifest as decreased color vision, contrast sensitivity and lowered perimetric sensitivity.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • AIDS/HIV