Abstract
Purpose: :
To use the 30 Hz flicker electroretinogram (ERG) to compare retinal function in diabetic patients (DP) and non-diabetic patients (NDP) with elevated lipid levels.
Methods: :
Lipid profiles, fasting blood sugars, were collected. The diabetic patients' HbA1c were collected, as well. All patients had a Snellen visual acuity eligibility range of 20/20-20/40. The diabetic patients (DP) were age matched with non-diabetic patients (NDP). NDP Photopic 30 Hz flicker were recorded according to the ISCEV standard protocol using Epic 4000 system (LKC Technologies). Eyes were dilated and a DTL electrode was used for recording. Implicit time (IT) and amplitude (AMP) of the ERG were measured by placing cursors on the waveform.
Results: :
20 patients were included in the study. 10 DP and 10 NDP. The age range of the DP=39-86yrs, avg 67.9yrs +13.9 ; NDP=39-81yrs, avg 67.6yrs +11.8. Lipid levels were: Cholesterol (CH) avg: DP=169.1mg/dl +50.65, NDP=178.1mg/dl +37.7 (p=ns); Triglycerides (TG) avg: DP=109.3mg/dl +41.9, NDP= 85.2mg/dl +38.68(p≤0.05); Low density lipoprotein (LDL) avg: DP= 91.8 mg/dl +37.5, NDP=96.3 mg/dl +27.9 (p=ns); High density lipoprotein (HDL) avg: DP=52.7 mg/dl +14.4, NDP=63.8 mg/dl +23.4 (p≤ 0.03). For age matched group, there were 9 DP (18 eyes) and 9 NDP (18 eyes) : DP AMP range=46.9 - 118.2 uV; avg=75.94 uV + 19.09, NDP AMP=range 52.1 - 166.5 uV; avg =100.10 uV + 35.70 (p≤0.016, t-test), DP IT range=26.2 - 36.6 msec; avg=29.80 msec + 3.72, NDP IT range=26.3 - 35.7 msec; avg =29.03 msec + 3.11 (p=ns, t-test). Using chi square analysis of the age matched DP and NDP: in patients with elevated TG ≥ 100 mg/dl and implicit times≥ 32 msec or below, the implicit times were increased in DP vs. NDP(p≤0.05, chi square). In patients with elevated cholesterol ≥150 and implicit times ≥ 32 msec or below, DP had a greater delay in implicit time than NDP(p≤ 0.05, chi square). For DP, using regression analysis, Implicit time vs. LDL was significant(p≤0.036).
Keywords: diabetic retinopathy • electroretinography: clinical • lipids