Electroretinogram in adult-onset diabetes mellitus
Okumura, T.; Kawasaki, K.; Nakagawa, H.; Kido, M.; Ishida, H.
Nippon Ganka Gakkai Zasshi 85(11): 2023-2029
1981
ISSN/ISBN: 0029-0203 PMID: 7337124 Document Number: 171372
The oscillatory potential (OP) of the electroretinogram (ERG) was previously found to diminish frequently in diabetes mellitus. Changes in the OP are described with special reference to its peak latency in 504 eyes of 282 patients with adult-onset diabetes, aged 15-69 yr. Patients with juvenile-onset diabetes and secondary diabetes were excluded. Those with advanced arteriolar sclerosis of the retina (3rd or 4th stage of Scheie's classification) or with refractive error beyond 3 diopters were excluded. Of 504 eyes studied 282 showed no ophthalmoscopically visible diabetic retinopathy (Scott O). Eyes (83) were at the 1st stage of Scott (Scott I), 87 eyes at the 2nd stage (Scott II), 52 eyes at the 3rd stage (Scott III). Previously described electrodes and apparatus for ERG recordings were used. Stimulus light was provided by a Xe discharge tube operated at an input energy of 20 J. The amplifier time constant was 0.003 s. The ERG was recorded after a preliminary dark adaptation of 5 min. After the terminology by Yonemura et al the positive peaks of the OP were tentatively designated as O1, O2, O3 and O4; the negative peaks as N1, N2 and N3. The sum of the amplitudes of O1, O2, O3 and O4 in each individual is expressed by the symbol .SIGMA.O; the sum of the amplitudes of N1, N2 and N3 by .SIGMA.N. The peak latency and amplitude of the OP beyond a range of M .+-. 2.sigma., where M and .sigma. represent, respectively, the mean and SD in normal control subjects, were estimated as abnormal. The results were recorded. The .SIGMA.O was decreased (below the lower limit of the normal range) in 45 eyes of Scott O (16.0%), 14 eyes of Scott I (16.9%), 21 eyes of Scott II (24.1%) and 34 eyes of Scott III (65.4%). The .SIGMA.N was decreased (below the lower limit of the normal range) in 40 eyes of Scott O (14.2%), 11 eyes of Scott I (13.3%), 17 eyes of Scott II (19.5) and 33 eyes of Scott III (63.5%). The mean of the amplitude (.SIGMA.O and .SIGMA.N) was significantly smaller in Scott III than in Scott II (P < 0.01). The 1st deflection (O1) of the OP was more frequently prolonged than the other succeeding deflection of the OP (O2, O3, O4, N1, N2 and N3). The peak latency of O1 was prolonged in 160 eyes of Scott O (56.7%), 60 eyes of Scott I (72.3%), 70 eyes of Scott II (80.5%) and 45 eyes of Scott III (86.5%). The peak interval between O1 and O2 was prolonged in 60 eyes of Scott O (21.4%), 22 eyes of Scott I (26.5%), 21 eyes of Scott II (24.1%) and 12 eyes of Scott III (23.1%). The mean of the amplitude .SIGMA.O was smaller and the mean of the peak latency of the O1 was longer in diabetics even with no apparent retinopathy, as compared with the means in the non-diabetic control subjects. The mean of .SIGMA.O was decreased and the mean of O1 peak latency was prolonged progressively with the advancement of the stage of retinopathy. A selective delay of the peak latency of the OP signifies an early retinal dysfunction, and a depression of the amplitude represents circulatory disorders, hypoxia or metabolic disturbances in advanced stages of retinopathy in adult-onset diabetes.