Session Title: FP-14 Vascular Diseases and Diabetic Retinopathy IV
Session Date/Time: Saturday 13/09/2014 | 16:30-18:00
Paper Time: 16:30
Venue: Boulevard F
First Author: : A.Maa USA
Co Author(s): : E. Pillow W. Feuer Q. Davis R. Caywood T. Brown S. Fransen
Diabetic retinopathy (DR) is one of the leading causes of preventable blindness in the world and screening reduces visual impairment. Screening rates are low in the United States (56.9%). There are barriers to obtaining routine eye care in the clinic, and fundus photography has a 15% failure rate. The retinal implicit time, obtained by a 30 Hz flicker electroretinogram (ERG) stimulus, correlates with the extent of DR. Using ERG for DR screening has many limitations, including difficulty in performing an ERG and interpreting the results. This study measures the performance of a new ERG device, RETeval, that eliminates these problems.
This study was performed at two Veteran Affairs (VA) medical centers in the United States, Atlanta, Georgia and Oklahoma City, Oklahoma.
Diabetic participants signed an informed consent to participate in this institutional review board (IRB) approved study. 500 diabetic patients were selectively recruited to obtain 80 patients for the following categories: 1) No diabetic retinopathy; ETDRS level 10. 2) Mild non-proliferative diabetic retinopathy (NPDR) without clinically significant macular edema (CSME); ETDRS levels 14-35. 3) Moderate NPDR without CSME; ETDRS levels 43-47. 4) Mild or moderate NPDR with CSME; ETDRS levels 10-47. 5) Severe NPDR or proliferative diabetic retinopathy (PDR); ETDRS levels 53 and higher. First, the RETeval test was performed on the subjects. An Amsler grid test was performed and then, on about 20% of the subjects, the RETeval test was repeated to assess test precision. Patients were dilated with tropicamide and phenylephrine eyedrops and Early Treatment Diabetic Retinopathy Study (ETDRS) compliant 7 field stereo fundus photographs were taken. These photographs were double-read in a masked fashion in a dedicated reading center (Inoveon). Photographic results which differed by more than 1 ETDRS step were sent to adjudication where two readers and a retinal specialist conferred to determine the final ETDRS designation. The adjudicated photography results served as the gold standard to which the RETeval findings were compared.
392 patients completed the study. There were 340 male and 52 female, with the following racial/ethnic groups: 192 Caucasian, 170 AFriday 12 Septembercan Americans, 16 Native Americans, 9 Hispanic, 1 Asian, and 4 “other”. The majority of patients, 375, were Type II diabetics and 17 were Type I diabetics. 127 patients were insulin dependent, 121 were on oral hypoglycemic agents, and 144 were on both oral pills and insulin. The average duration since diagnosis was 80 months (range 1-421). The RETeval device had a technical failure rate (no results generated) of 0.5% (2/392 patients) whereas ETDRS fundus photography (ungradeable images) had a significantly higher (p<0.001, exact McNemar test) technical failure rate of 15% (57/392 patients). Upon case-by-case review, one RETeval failure occurred when testing a subject with sub-1 mm pre-dilation pupil diameter. This individual only dilated to 3.5 mm, which limited the photography, but the RETeval device was able to generate results on that particular subject after dilation. The second RETeval failure was related to poor electrical measurements. The data illustrates how RETeval is easier to perform on patients than fundus photography, and is less affected by factors such as media opacity or patient cooperation.
The RETeval device is a new 30 Hz flicker ERG device that shows promise as a new DR screening tool. It has several advantages over current clinical methods. Testing time with the RETeval device is only a few minutes per patient, with no dilation or other patient preparation required. Testing was performed by a technician with minimal training, not an ophthalmologist or optometrist. RETeval was performed quickly in the office without requiring the patient to travel to a different clinic. Compared to fundus photography, the RETeval device demonstrated a very small technical failure rate that was statistically significant. This study demonstrated that the RETeval device shows promise as a new screening tool for diabetic retinopathy because of its ease of use, portability, and low screening failure rate.