Changes in multifocal electroretinograms induced by transpupillary thermotherapy.
OBJECTIVE
To determine retinal function after transpupillary thermotherapy (TTT) for subfoveal choroidal neovascularization using multifocal electroretinograms (mfERGs).


METHODS
Multifocal electroretinograms were recorded before and after TTT (wavelength, 810 nm; diameter, 3 mm; duration, 60 seconds; power, 350 mW) in 9 eyes in 9 patients with subfoveal choroidal neovascularizations. The stimulus consisted of 7 hexagons; the central hexagon covered the laser-irradiated area and the surrounding 6 hexagons covered the nonirradiated area. Each recording was completed within 1 minute, and mfERGs were recorded periodically during the first 60 minutes after TTT and also at 24 hours and 1 week after TTT.


RESULTS
The amplitude of mfERGs from irradiated areas was significantly reduced at 1 minute after TTT (P< .01) and then recovered soon. The peak time was prolonged at 15 minutes after TTT (P< .01), recovered to pre-TTT levels at 60 minutes, and then was prolonged again at 24 hours (P< .05) and 1 week (P< .05) after TTT. The mfERGs in nonirradiated areas were unchanged during the observational period.


CONCLUSIONS
We found amplitude reduction in central focal ERGs at 1 minute after TTT, transient peak-time delay at 15 minutes, and a delay at 24 hours. Early reduction is probably directly caused by an increase in temperature during TTT as previously reported in focal flicker ERGs. Peak-time delays at 15 minutes and 24 hours may be caused by other factors, such as increased intracellular calcium (Ca(2+)), the release of nitric oxide or heat shock proteins, vasodilation, or change in choroidal neovascularization. Our findings indicate that recording mfERGs may be a useful tool for evaluating TTT procedures.
Shimada
Yoshiaki
Y
Department of Ophthalmology, School of Medicine, Fujita Health University, 1-98 Toyoake, Aichi 470-1192, Japan.
Horiguchi
Masayuki
M
D000328:Adult; D000368:Aged; D020256:Choroidal Neovascularization / Q000628:therapy*; D004596:Electroretinography; D005260:Female; D005584:Fovea Centralis; D006801:Humans; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011680:Pupil; D012160:Retina / Q000503:physiopathology*; D012164:Retinal Diseases / Q000209:etiology* / Q000503:physiopathology*