Assessment of Retinal Function in HIV Patients Without Infectious Retinitis With Various CD4 Counts by Multifocal Electroretinogram and Automated Perimetry Studies

Abstract

Abstract: : Purpose:We and others have previously shown that there is vision loss in HIV positive patients which can be documented by visual psychophysical tests. In addition we have recently shown that there is a loss of retinal nerve fiber layer in these patients (Kozak & Freeman, AJO In Press). We have hypothesized that this may be due to the cumulative effects of retinal microvascular disease causing retinal capillary drop out and cotton wool spots. We therefore wished to determine if multifocal electroretinogram (mfERG) first order kernel testing would show abnormalities corresponding to perimetric defects in such patients in the era of HAART. Methods: We studied three groups of patients: HIV negative controls, HIV high CD4 nadir patients (lowest CD4 T cell count over 100) and low CD4 nadir patients (lowest CD4 T cell count below 100 for over 6 months). 26 HIV positive eyes and 16 HIV negative control eyes were studied by mfERG. A subset of 10 eyes also underwent computerized perimetry for comparison. We analyzed mfERG by hexagons as well as by quadrants. Results:Of 103 hexagon locations studied, there was no significant difference in any locations of the amplitudes (nV/degree) between the three groups (p>0.05), similarly, the latencies were not different (p>0.05 Tukey–Kramer). Typical mean±SD values of amplitude P1 (nV/degree) across the Control, High CD4 and Low CD4 groups by hexagons located 15 degrees superior and inferior to the fovea were: Controls: 17.5±10.4; High CD4: 13.6±8.2; Low CD4: 16.3±9.7; p=0.55 (hexagon 30); Controls: 19.7±12.1; High CD4: 15.6±8.1; Low CD4: 22.2±16.3; p=0.42 (hexagon 64). We carefully studied HIV eyes with significant visual field defects at the 0.05, 0.02, 0.01 and 0.005 level (Humphrey pattern deviation; 24–2) and compared mfERG amplitudes and latencies at those locations. 7 eyes had at least 2 defects at the 0.02 level; there was no corresponding defect in the mfERG data. Conclusions: In the era of HAART there is still damage to the visual field and retina. Our mfERG studies show that the damage appears to effect the inner retina, the outer retina is spared. Further studies of inner retina function (mfERG – second order kernel and mfVEP) are indicated.

Keywords: AIDS/HIV • electroretinography: clinical • retina