DIFFERENTIAL-EFFECTS OF COMPRESSION AND SUCTION OPHTHALMODYNAMOMETRY ON THE SCOTOPIC BLUE-FLASH ELECTRORETINOGRAM

Several studies have investigated the effect of elevated intraocular p ressure with reduced ocular perfusion pressure on visual neural functi on by means of compression and suction ophthalmo dynamometry. We compa red the effects of nominally equivalent reductions in the ocular perfu sion pressure induced by compression and suction ophthalmodynamometry retinal function as measured by flash electroretinography. Scotopic bl ue-flash electroretinograms were recorded in five subjects for baselin e conditions; during a 40% reduction in the ocular perfusion pressure effected in a first test session by compression ophthalmodynamometry; and then in a second test session some 4 hours later by suction ophtha lmodynamometry. Fifteen consecutive electroretinographic sets were rec orded during scleral compression or suction, and also after compressio n or suction was removed. Compression and suction ophthalmodynamometry decreased the electroretinogram b-wave to different degrees; overall, the electroretinogram was attenuated more by compression than by suct ion ophthalmodynamometry. In the recovery phase, the group averaged b- wave quickly increased to exceed baseline after both scleral compressi on and suction. The trends for prolonged implicit times over the durat ion of the study were similar for compression and suction ophthalmodyn amometry.