Abstract
Purpose:
Pattern VER to assess optic nerve function in diabetic patients with good visual acuity. Diabetic patients are at increased risk of glaucoma. In addition diabetic optic neuropathy can occur with various stages of diabetic retinopathy. Pattern VER is now being used to assess glaucoma patients.
Methods:
Retrospective chart review of the database of 3500 computerized records for the ICD-9 diagnosis code of diabetic retinopathy (362.83. 362.03. 362.02), glaucoma suspect (365.00), glaucoma (365.11) who had the procedure code of 95930 for visual evoked response (VER). Inclusion criteria: diabetic retinopathy, glaucoma suspect, and glaucoma patients, Snellen visual acuity: 20/15-20/40. Exclusion criteria: optic neuritis, multiple sclerosis, optic neuropathy from other causes (drug toxicity, pituitary disease, CNS disease etc) or multiple diagnoses. Controls were normal volunteers, patients with no detectable ocular pathology but had diagnosis of non-specific headache (ICD-9 code 379.91). Visual acuity was 20/15-20/40. The Stata statistical software program was used. For each patient or control subject, VER data from only one eye was used (randomization by coin toss). Using Pattern VER (LKC, Gaithersburg MD, EM software), we measured the P100 amplitude (P100amp), P100 implicit time (P100IT), N75 implicit time (N75IT).
Results:
Total of 80 patients enrolled: Controls (C):C=20: age range 21-78 yrs, avg=53.75, sd=15.2; Diabetes (DM): n=20: age range 45-83 yrs, avg=61.9, sd=12.05. Glaucoma Suspect (GS)=20: age range 33-78, avg=54.6, sd=13.2; POAG (G)=20: age range 43-78 yrs, avg=65.2, sd=11.3. N75 Imp time (N75IT) 2 tailed t-test: C mean 30.9 msec vs G mean 49.4 msec, p=0.0001; C mean 30.9 msec vs DM mean 42.3 msec, p=0.0001; G mean 49.4 msec vs GS mean 34.6 msec, p=0.0002; G mean 49.4 msec vs DM mean 42.3 msec, p=0.0051; DM mean 42.3 msec vs GS mean 34.6 msec, p=0.03. No significant differences were noted in N75IT between C vs GS: p=0.3. No significant differences were noted in P100amp, P100IT: DM vs C; GS vs C; G vs C.
Conclusions:
Pattern VER has objectively quantified optic nerve pathology in POAG patients. This small study suggests that diabetic patients with good visual acuity may have early optic nerve pathology as shown in the delay of N75 implicit time. Future randomized clinical trials will be needed to further corroborate these findings.
Keywords: 499 diabetic retinopathy •
507 electrophysiology: clinical •
613 neuro-ophthalmology: optic nerve