|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1996 : ¥1,500,000 (Direct Cost : ¥1,500,000)
Purpse : Scannning laser ophthalmoscope (SLO) microperimetry detects foal retinal sensitivity and simultaneouly monitors the fundus. We recorded the focal electroretinogram (ERG) and focal visual evoked potentials (VEP) using SLO microperimetry to investigate the best stimulus condition for recordings.
Methods : We used a Buriann-Allen electrode for ERG recording and a silver-silverchloride electrpodes for VEP recording. SLO microperimetry was used to stimulate the retina and to monitor the fundus. The intensity of background illumination was 10 cd /m^2. The stimulus duration was 100 ms.The stimulus light was a He-Ne laser beam (0 dB : 6200 cd/m^2), which could be altered in size and strength. ERG and VEP were recorded simultaneously and 50 responses were averaged.
Results : 1) Focal ERG : When the macula was stimulated with light the same size as the optic disc, the amplitudes of both a-and b-waves increased with increases in the stimulus intensity. However, they did not increase with stimuli stronger than 25 dB.When the optic disc was stimulated in order to determine the effect of scattering light, ERG could not bc recorded with light weaker than 23 dB.The largest ERG was recorded at the macula, and both a-and b-waves became smaller when the nasal or temporal area of the macula was stimulated. With a decrease in the size of the stimuli, the amplitudes of both a-and b-wave bicame smaller. However, the b-wave was recordable with a stimulus of 100 min.
2) Focal VEP : Useful VEP recordings were not obtained in this investigation, due to a large stimulus to noise ratio (S/N ratio).
Conclusion : Focal ERG could berecorded using SLO microperimetry. The intensities of 25 or 27 dB were thought to be suitable for focal ERG recordings.