b'DEALING WITH DETERIORATING VISIONWe surveyed hundreds of horseincluded details regarding treatment ofkeratitis (fungal infection of the cornea) owners in Queensland, Australia, andspecific ocular conditions because theyadvances to infection within the globe only 3.3% of those owners felt that theirlie beyond this articles scope. (eyeball) or the corneal disease becomes horse had a medical concern involvingDwyer encourages owners to maintainso severe that enucleation (eye removal) their eyes. We subsequently conductedan open mind as they read this article.is required, says Dwyer. Fungal keratitis complete ocular examinations in 339 ofIts very important for owners to recog- that is severe frequently results in vision the 974 horses we obtained completednize that many horses without any visionloss, even if the keratitis is eventually surveys for and found that almost 88%at all can be successfully managed andcontrolled.actually had abnormal ocular findings,potentially even continue to compete ath- A simple injury can quickly manifest says lead author Fernando Malalana- letically, she says. Deteriorating vision isinto an even larger, more complex, ex-Martinez, DVM, GPCert(EqP), Dipl.not synonymous with a death sentence. pensive, and potentially eye-threatening ECEIM, FHEA, MRCVS, senior lecturercondition, she adds. Never wait to have in equine internal medicine at the Univer- Leading Ocular Abnormalitiesany horse with any eye problem exam-sity of Liverpools Institute of VeterinaryTraumaConsidering the large size ofined by a veterinarian. Science, in the U.K. the horses eyes relative to his head andCataracts and retinal atrophyIn the proximity of those eyes to the ground,addition to trauma, leading causes of where dust and debris, vegetation, andocular abnormalities noted in our study An estimatedother horses tails and feet tend to aggre- included cataracts and age-related retinal gate, its no surprise that trauma remainsatrophy, says Malalana-Martinez.1-2% a leading cause of equine ocular issues.Specifically, 34.3% of the horses Trauma causing injury to the surfacehad cataracts and 31.8% had senile or of the U.S. horseof the eye, called the cornea, is usuallyage-related retinal atrophy, which is readily observable, says Dwyer. A red,degeneration of the membrane lining the population suffers somepainful, swollen eye that the patient holdsback of the eye that essentially transmits form of blindness closed with an obvious defect or eveninformation from the eye to the brain. embedded foreign body makes diagnosisAn additional 10.1% of examined horses relatively straightforward. also had so-called bullet-hole lesions in Indeed, data collected in the above- their retinal tissues, which are pin-sized An estimated 1 to 2% of the Americancited survey by Malalana-Martinez anddefects that might or might not impair equine population currently suffers uni- colleagues showed that owners morevision.lateral (in one eye) or bilateral (in both)readily identify corneal lesions (thanCataracts are areas of focal or diffuse blindness, equivalent to approximatelyother types of ocular abnormalities),cloudiness within the lens of the eye, 95,000-190,000 horses. This is a substan- which often occur in cases of trauma.says Dwyer. As with other species, cata-tial number of horses, making vision lossMalalana-Martinez did additionallyracts can affect vision, and both mature an important issue in equine operations,note, however, that very few ownersand hypermature (beyond full develop-Dwyer adds.reported an ocular traumatic injury as ament) cataracts can be blinding.Lets take a closer look at potentialspecific entity0.3% of 974 horses. In terms of the retina, I think probably causes of ocular abnormalities and visionTrauma cases must be addressed im- senile atrophy is more significant to these loss in horses. Well also describe behav- mediately because secondary infections horses than bullet-hole lesions, as these iors and signs you can watch for thatboth bacterial and fungalcan develophave to be quite extensive to significantly suggest visual impairment. Finally, wellrapidly, potentially leading to moreaffect a horses vision, says Malalana-review management strategies for helpingadvanced and serious disease, includingMartinez. horses deal with deteriorating eyesightmelting corneal ulcers.UveitisThe most common cause of and blindness. However, we haventSome horses lose vision if ulcerativeblindness in horses is equine recurrent PHOTOS COURTESY DR. FERNANDO MALALANA-MARTINEZThe eye conditions that most commonly cause vision loss in horses are (left to right) cataracts, equine recurrent uveitis, and glaucoma.24November 2018The Horse | TheHorse.com'