The effects of cataract stage, lens-induced uveitis and cataract removal on ERG in dogs with cataract.
OBJECTIVE
The purpose of this study was to determine the effects of cataract stage, lens-induced uveitis and cataract removal on the electroretinogram (ERG) of dogs with cataract.


METHODS
Fifty-seven dogs diagnosed with unilateral or bilateral cataract whose ERG was recorded at Rakuno Gakuen University Teaching Animal Hospital from 2001 to 2004.


METHODS
Four responses were recorded during the ERG: rod ERG, standard combined ERG, single-flash cone ERG and 30-Hz flicker ERG. Cataracts were divided into four stages: incipient, immature, mature and hypermature, and with or without lens induced uveitis (LIU). Noncataractous eyes of dogs with unilateral cataract were used as the control. We compared ERG amplitude, implicit time, and the b- to a-wave amplitude ratio of cataractous vs. noncataractous eyes, preoperative vs. postoperative cataractous eyes, and cataractous eyes with and without LIU.


RESULTS
No significant difference was found in ERG amplitude between incipient, immature and hypermature cataractous eyes, while in mature cataractous eyes decreased amplitude was confirmed in all responses compared with control eyes. However, no significant difference in b/a ratio was found at any stage of cataract. In postoperative eyes, increased amplitude was recorded in all responses compared to preoperative values. In eyes with LIU a decreased amplitude in the rod ERG and b-wave of standard combined ERG was recorded and, furthermore, a significant decline was confirmed in b/a ratio.


CONCLUSIONS
ERG values were influenced by cataract stage and LIU. LIU was associated with a reduction in the b/a ratio.
Maehara
Seiya
S
Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan. seiya-m@rakuno.ac.jp
Itoh
Norihiko
N
Wakaiki
Shinsuke
S
Yamasaki
Ayako
A
Tsuzuki
Keiko
K
Izumisawa
Yasuharu
Y
D000818:Animals; D002386:Cataract / Q000473:pathology / Q000662:veterinary*; D002387:Cataract Extraction / Q000379:methods / Q000592:standards / Q000662:veterinary*; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D004596:Electroretinography / Q000379:methods / Q000662:veterinary*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014605:Uveitis / Q000209:etiology / Q000473:pathology / Q000662:veterinary*