title: Application of visual evoked potentials for preoperative estimation of visual function in eyes with dense cataract.
abstract: 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.
authors.affiliation: Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, Graduate School, Japan. m.kiyosawa.oph@tmd.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Mori
authors.forename: K
authors.initials: K
authors.lastname: Momose
authors.forename: N
authors.initials: N
authors.lastname: Nemoto
authors.forename: F
authors.initials: F
authors.lastname: Okuyama
authors.forename: Y
authors.initials: Y
authors.lastname: Kimura
authors.forename: M
authors.initials: M
authors.lastname: Kiyosawa
authors.forename: M
authors.initials: M
authors.lastname: Mochizuki
mesh_terms: 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