Investigation on the distinct electroretinogram in dogs with different cataract stage and ocular disease

• Main Authors: Szu-Hui Huang, 黃偲惠
• Other Authors: Feng-Pang Cheng
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/64724424996511970864

碩士 === 國立中興大學 === 獸醫學系暨研究所 === 97 === Electroretinogram (ERG) recording is a valuable noninvasive tool in the evaluation of retinal function. ERG is mainly utilized for the early diagnosis of progressive retinal atrophy (PRA) and pre-operative evaluation of retinal function in canine cataract patients by recognition of the amplitude and implicit time of a-wave and b-wave. Many breeds are genetically predisposed to both cataracts and PRA. Funduscopic signs of retinal degeneration cannot be visible in dogs with mature cataract formation. ERG is a potential which arises in the retina after light stimulating and can be used to assess the retinal function in the presence of an opaque medium like cataract. ERG is an indispensable procedure to assess retinal function and to eliminate cataract patients with retinal degeneration before cataract surgery, in order to restore vision postoperatively. In recent years, ERG is extensively utilized for the pre-operative evaluation of retinal function in canine cataract patients. Nevertheless, there are barely few research mention that the effects of cataract and other ocular disease on ERG in dogs. Therefore, the goal of our study was to investigate the effects of different stage of cataract and other ocular disease (such as lens-induced uveitis and corneal disease) on the consequence of ERG. The short ERG protocol was used and cooperated with Zoletil, functioning as the tranquilizer. Data of normal dogs quoted from previous study, which previously conducted in our lab was used as reference data. Results: Senile cataract dogs exhibited greater extent of a decreasing a- and b-wave amplitude than adult cataract dogs. There was significant difference on ERG results in different age of cataract dogs, while no significant ERG difference in different gender. As compared the ERG data between different cataract stage of dogs and normal dogs (reference data), dogs with mature cataract displayed that significant decline of b-wave amplitude after dark adaption for 5 minutes (P<0.05). ERG data of cataract dogs with lens-induced uveitis (LIU) revealed a decrease in b-wave amplitude comparing to the cataract dogs without LIU, however, difference was not statistically valid. Dogs with diffused corneal pigmentation exhibited a higher drop of b-wave amplitude than dogs with focal corneal pigmentation. There was a significant correlation between the range of corneal pigmentation and b-wave amplitude. Adding it up, ERG is an indispensable procedure before cataract surgery. Thus, ERG can be used to assess the retinal function in the presence of an opaque medium like cataract. However, many vital variables influence the ERG consequence, leading to misdiagnose of the ERG data, expressing as retinal function. For these reasons, one should take the effects of variables (like age, stage of cataract and corneal disease) into consideration on interpretation of ERG data.