Visual Prognostic Value of Ocular Electrophysiology Tests in Corneal Transplantation
Atiporn Thuangtong MD*, Patthanee Samsen MD*, Ngamkae Ruangvaravate MD*, Chantaka Supiyaphun MD*
Affiliation : * Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Bangkok, Thailand
Objective : To determine visual prognostic value of electrophysiologic tests in unilateral-eye-disease patients who underwent
corneal transplantation.
Material and Method: Retrospective charts of the patients who underwent unilateral optical penetrating keratoplasty at
Siriraj Hospital from September 2003-June 2009 were reviewed. The amplitude of a-wave and b-wave in dark-adapted
bright flash ERG and the amplitude of major positivity (P2) in flash VEP were recorded and compared with the good fellow
eye. Area under receiver operating characteristic curve (AUC) was used to determine the best predictor of good visual
prognosis. Positive predictive value (PPV) and negative predictive value (NPV) were used to determine the accuracy of the
tests.
Results : Thirty-nine patients were included. The present study showed that a-wave amplitude was a good predictor (AUC =
0.83). For a-wave amplitude that was equal to or more than 80% and P2 amplitude that was equal to or more than 67%, PPV
was 95.65%.
Conclusion : The a-wave amplitude and P2 amplitude predict good visual outcome most accurately when changing less than
20% and 33%, respectively, compared to the normal fellow eye.
Keywords : Electrophysiologic test, Corneal transplantation
