title: Monitoring retinal function during transpupillary thermotherapy for occult choroidal neovascularization in age-related macular degeneration.
abstract: OBJECTIVE
  To use focal electroretinography to evaluate changes in retinal function during transpupillary thermotherapy (TTT) for neovascular age-related macular degeneration (ARMD).
  
  
  METHODS
  Sixteen eyes of 16 patients with ARMD with occult choroidal neovascularization (CNV) were studied. A 630-nm photocoagulator aiming beam was modified for use as a 41-Hz square-wave focal electroretinogram (fERG) stimulus. The stimulus was presented on a light-adapting background by a Goldmann-type lens (visual angle, 18 degrees; mean luminance, 50 cd/m(2)). fERGs were continuously monitored before, during, and after TTT for occult CNV. The amplitude and phase of the fERG's fundamental harmonic were measured.
  
  
  RESULTS
  No suprathreshold or adverse clinical events occurred during the course of the study. fERG amplitude decreased transiently during TTT (23% +/- 9% [SE]; P < 0.05). The decrease in amplitude was greatest 16 to 20 seconds and 32 to 40 seconds after the onset of TTT. It was followed by a recovery to baseline amplitude during TTT (48 to 60 seconds after TTT was begun). Within 60 seconds after TTT was completed, fERG amplitude was within the range of baseline. TTT did not alter the fERG phase. Mean fERG amplitudes and phases recorded 1 week and 1 month after TTT were comparable to mean pretreatment levels.
  
  
  CONCLUSIONS
  fERG amplitude decreases transiently during TTT, despite the absence of ophthalmoscopically apparent lesions. Intraoperative amplitude depression may result from an adaptation effect to laser light energy and/or hyperthermia, resulting in desensitization of cone photoreceptors and bipolar cells. Treatment sites are electrophysiologically functional 1 month after TTT. Detailed parametric study of a larger patient group is needed to determine whether fERG testing is potentially useful for monitoring and perhaps for controlling and optimizing TTT for choroidal neovascularization.
authors.affiliation: Institute of Ophthalmology, Catholic University of S Cuore, Rome, Italy. md0571@cmlink.it
authors.forename: Benedetto
authors.initials: B
authors.lastname: Falsini
authors.forename: Francesco
authors.initials: F
authors.lastname: Focosi
authors.forename: Fernando
authors.initials: F
authors.lastname: Molle
authors.forename: Chiara
authors.initials: C
authors.lastname: Manganelli
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Iarossi
authors.forename: Antonello
authors.initials: A
authors.lastname: Fadda
authors.forename: Giorgio
authors.initials: G
authors.lastname: Dorin
authors.forename: Martin A
authors.initials: MA
authors.lastname: Mainster
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020256:Choroidal Neovascularization / Q000209:etiology / Q000628:therapy*; D004596:Electroretinography / Q000379:methods*; D005260:Female; D006801:Humans; D006979:Hyperthermia, Induced; D008268:Macular Degeneration / Q000150:complications / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D012160:Retina / Q000502:physiology*