Validity, Usefulness and Cost of RETeval System for Diabetic Retinopathy Screening.

PURPOSE: We studied the validity, usefulness, and relative cost to detect diabetic retinopathy (DR) and sight-threatening DR (STDR) by using a hand-held electrophysiologic tool compared to digital fundus photography. METHOD: Patients with diabetes attending the screening unit of King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia were evaluated by "RETeval", Amsler grid, and digital dilated fundus photography. Fundus images were evaluated by a retina specialist to determine grade of DR. The sensitivity and specificity of STDR and DR screening compared to photography were calculated, as well as "RETeval" combined with Amsler grid testing. The area under the curve (AUC) of "RETeval" screening outcome was calculated. RESULT: We analyzed data of 400 diabetic patients. The prevalence of DR of any grade was 48.8% (95% confidence interval [CI], 43.9-53.7) while the prevalence of STDR was 27% (95% CI, 22.6-31.4). The outcome of RETeval test was "fail" (based on 20 µV or more amplitude of electrophysiologic spikes) in 351 (87.8%; 95% CI, 84.5-91.0) eyes. The sensitivity of the device was 95.4% and the specificity was 17.5%. Thus, the sensitivity of sequential testing with RETeval and Amsler grid test was 30.1% and the specificity was 80.1%. The AUCs for STDR and DR in general were 76.6% and 50.6%, respectively. CONCLUSIONS: "RETeval" is a rapid screening device with excellent sensitivity for detecting STDR. It has potential as a first level screening tool to detect patients who require further evaluation. TRANSLATIONAL RELEVANCE: Retinal function, such as electrophysiology, can be used as a new concept for screening for DR.

Visual function assessment in simulated real-life situations in HIV-infected subjects.

Visual function abnormalities are common in people living with HIV disease (PLWH) without retinitis, even after improvement in immune status. Abnormalities such as reduced contrast sensitivity, altered color vision, peripheral visual field loss, and electrophysiological changes are related to a combination of retinal dysfunctions, involving inner and outer retinal structures. The standard protocol for testing vision performance in clinical practice is the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. However, this method poorly correlates with activities of daily living that require patients to assess visual stimuli in multiple light/contrast conditions, and with limited time. We utilized a novel interactive computer program (Central Vision Analyzer) to analyze vision performance in PLWH under a variety of light/contrast conditions that simulate stressful and real-world environments. The program tests vision in a time-dependent way that we believe better correlates with daily living activities than the non-timed ETDRS chart. We also aimed to correlate visual scores with retinal neuro-fiber layer thickness on optical coherence tomography. Here we show that visual acuity is more affected in PLWH in comparison to HIV-seronegative controls in varying contrast and luminance, especially if the nadir CD4+ T-cell count was lower than 100 cells/mm3. Visual impairment reflects the loss of retinal nerve fiber layer thickness especially of the temporal-inferior sector. In PLWH the ETDRS chart test led to better visual acuity compared to the Central Vision Analyzer equivalent test, likely because patients had indefinite time to guess the letters. This study confirms and strengthens the finding that visual function is affected in PLWH even in absence of retinitis, since we found that the HIV serostatus is the best predictor of visual loss. The Central Vision Analyzer may be useful in the diagnosis of subclinical HIV-associated visual loss in multiple light/contrast conditions, and may offer better understanding of this entity called "neuroretinal disorder".

Assessment of retinal function in patients with HIV without infectious retinitis by multifocal electroretinogram and automated perimetry.

PURPOSE: To determine if multifocal electroretinogram (mfERG) testing shows abnormalities that correspond to perimetric defects in HIV positive patients without infectious retinitis. METHODS: We studied three groups of patients: HIV negative controls, HIV high CD4 nadir patients (lowest CD4 T cell count is over 100) and low CD4 nadir patients (below 100 for over 6 months). Twenty-six 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 and rings. RESULTS: Of 103 hexagon locations there was no significant difference in the amplitudes P1 and N1 (nV/degree) between the three studied groups (p>0.05), similarly, the latencies were not different (p>0.05). All eyes with significant visual field defects at the 0.01 and 0.005 level (Humphrey pattern deviation; 24-2) were compared to mfERG amplitudes and latencies at those locations-there were no corresponding defects in mfERG data (p>0.2). CONCLUSION: In the era of HAART there are still demonstrable visual field defects and other evidence of damage to the retinal nerve fiber layer in HIV patients. Our mfERG studies show that the damage appears to affect the inner retina, the outer retina is spared. Further studies of inner retinal structure and function are indicated to elucidate this process.