Application of visual evoked potentials for preoperative estimation of visual function in eyes with dense cataract.
OBJECTIVE
To determine whether the temporal frequency characteristics of the visual system as determined by visually evoked potentials (VEP) can be used for a preoperative estimation of the visual function in eyes with cataracts.


METHODS
Light stimuli driven by a pseudorandom binary sequence (PRBS) of 40950 ms duration were presented and EEG recordings were made from 13 control and 20 patients with cataracts preoperatively and 1 week after cataract operation. The first kernel of the PRBS-VEP was obtained as the first-order cross-correlation function between PRBS and PRBS-VEP. The Fourier transform of this function was used as the temporal frequency characteristic (TFC).


RESULTS
The mean +/- standard deviation of the latency and amplitude of the VEP in normal controls were 110.8+/-4.3 ms and 2.01+/-0.67 microV, respectively. A high correlation (r>0.7) between the pre-and postoperative VEP waveform was obtained in 13 eyes (65%), and 14 eyes (70%) in the VEP-TFC curves. The sensitivity of the examination was 73%, 27%, and 91% for the latency, amplitude and TFC of the VEP, respectively. The specificity of the examination was 67%, 100%, and 89% for the same measures. Eleven of 12 eyes with abnormal TFC preoperatively showed retinal or optic nerve lesions postoperatively. False-negative results were seen in cases with delayed corneal edema.


CONCLUSIONS
Postoperative visual function of patients with cataracts can be predicted by preoperative measurement of the TFC obtained by PRBS-VEP.
Mori
H
H
Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, Graduate School, Japan. m.kiyosawa.oph@tmd.ac.jp
Momose
K
K
Nemoto
N
N
Okuyama
F
F
Kimura
Y
Y
Kiyosawa
M
M
Mochizuki
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000503:physiopathology*; D002387:Cataract Extraction; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005188:False Negative Reactions; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007908:Lens, Crystalline / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009901:Optic Nerve Diseases / Q000175:diagnosis / Q000503:physiopathology; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012164:Retinal Diseases / Q000175:diagnosis / Q000503:physiopathology; D012680:Sensitivity and Specificity; D014792:Visual Acuity / Q000502:physiology*; D014794:Visual Fields