Electroretinogram evaluation of equine eyes with extensive ‘bullet‐hole’ fundic lesions

Abstract

Extensive bullet-hole chorioretinal lesions do not appear to compromise outer retinal function in these horses.

Prevalence of owner‐reported ocular problems and veterinary ocular findings in a population of horses aged ≥15 years

“…In addition, many of these lesions such as bullet-hole lesions (small areas of focal chorioretinitis) are typically incidental findings of no clinical significance [19]. The prevalence of owner-reported ocular lesions was markedly lower than the prevalence of ocular lesions detected by veterinary clinical ophthalmic examination.…”

“…Horses usually cope well with minor visual impairment in a familiar environment and owners may not notice their horse has a vision impediment until visual impairment is severe or there are changes in the horse's environment . In addition, many of these lesions such as bullet‐hole lesions (small areas of focal chorioretinitis) are typically incidental findings of no clinical significance .…”

Comparison of two sedation protocols for long electroretinography in horses using the Koijman electrode

“…Electroretinographic examination should ideally be performed under general anaesthesia, however sedation is preferred in horses due to the inherent risks associated with general anaesthesia [12]. Studies evaluating the effects of sedation on ERG in horses report the use of alpha-2 agonists alone [3,13], being detomidine, as a general rule, the drug of choice [2,7,9,10]. In our experience, detomidine seemed to be insu cient for some individuals that undergo the complete ECVO protocol.…”

“…Sedation ERG protocols using different alpha-2 agonists have been published in horses [2,7,9,10,13,15]. However, these do not eliminate all head movements during the procedure, which makes the examination less reliable and more time consuming [12].…”

“…In horses, ERG is routinely used prior to cataract surgery or for objective evaluation of diseases that affect the retina without changes in the ocular fundus examination [3][4][5][6]. It can also be utilized to quantify the functional damage of the retina when lesions are observed by indirect ophthalmoscopy [7]. Equine recurrent uveitis or glaucoma are other diseases in which ERG is indicated [5].…”