Findings:
- Within the vitreous chamber, there is a well-defined ovoid structure with a thin hyperechoic rim and measuring approximately 1.9 cm in diameter, representing the lens. Within the lens, there are multiple well-defined, radiating hyperechoic striations and peripheral surrounding hyperechoic layers (asterisk).
- Multifocally throughout the vitreous chamber, and extending into the anterior chamber, a mild to moderate amount of amorphous and inhomogeneous, as well as punctate echogenic material is seen.
- No definitive evidence of retinal detachment is identified.
Conclusions:
- Posterior left lens luxation with cataract, and vitreous chamber fibrin and/or cells and vitreal degeneration.
Follow-up:
- Full ophthalmic evaluation:
- Slight enophthalmos and blepharospasm.
- Absent menace response, dazzle and dPLR/cPLR.
- Palpebral reflex present.
- Multifocal areas of corneal epithelial fibrosis axially and temporally.
- Miosis. 2-3+ aqueous flare and diffuse fibrin in anterior chamber.
- Incipient cataract with brunescence appearance.
- Moderate vitreal haze.
- Not able to visualize detail on fundic exam.
- The patient was previously diagnosed with Equine Recurrent Uveitis, and the described ultrasonographic changes were thought to be chronic complications. Prognosis for return to functional vision in the left eye was deemed grave, even with medical or surgical therapy. Medical management was elected and aimed to maintain the patient comfortable. While it may delayed progression of disease, medical therapy may not prevent further deterioration of the patient’s condition.
A little bit more…
- Equine recurrent uveitis (ERU), also known as moon blindness or periodic ophthalmia (Allbaugh et al., Gerding et al.).
- It has a variably prevalence between countries and is reported to affect 2–25% of horses in the United States, 8–10% in Europe, and less than 1% in the United Kingdom. This difference may be due to genetic and environmental factors (Allbaugh et al., Kingsley et al.).
- ERU is marked by episodes of ongoing or recurring intraocular inflammation that usually appear months after the initial uveitis episode has resolved. If a uveitis episode recurs within a few weeks, it might be ERU or could indicate unresolved acute uveitis if the root cause wasn’t identified and treated properly, or if treatment wasn’t continued for 2–4 weeks after clinical signs disappeared (Allbaugh et al., Gerding et al.).
- Appaloosas, Draught breeds, Warmbloods and European horses are predisposed to ERU (Allbaugh et al., Kingsley et al.). Coat color may have an effect as well, and the same genetic marker associated with ERU in appaloosa could have been at play in the resented Pony of America gelding (also a spotted breed).
- Owners may observe occasional squinting, tearing, or cloudiness in their horse’s eyes weeks, months, or even years before seeking veterinary care. These symptoms often precede more persistent signs of eye pain, changes in eye appearance, or vision problems (Allbaugh et al.).
- Indicators of previous inflammatory episodes may include:
- Posterior synechia, pigment rests on the anterior lens capsule, iris hyperpigmentation, corpora nigra atrophy, lens subluxation, cataracts or inactive retinal lesions.
- End-stage changes may include:
- Phthisis bulbi, pupillary seclusion, blinding cataracts, luxated lenses and/or retinal detachment.
- Lens luxations may result from the effect of inflammation on the zonules or because of traction of fibrous adhesions (Cook et al.).
- Cataracts are staged based of the degree of lens involvement:
- ERU generally has a poor long-term outlook, but early detection of inflammatory episodes, proper treatment, and careful monitoring can enhance the chances of preserving vision. Appaloosas are particularly vulnerable, with the worst vision prognosis among breeds and an eightfold higher risk of developing ERU. However, placing a suprachoroidal cyclosporine implant is reported to be especially effective in managing ERU in this breed (Allbaugh et al.).
- In a study that looked at 224 horses with ERU (total of 338 eyes), the following outcomes were documented (Gerding et al.):
- Vision loss in 46.9% of eyes (including 28.4% at the initial examination)
- Globe loss in 12.1%
- Decreased performance in 60.8%
- Transfer of ownership in 19.1%
- Euthanasia in 14.9% of cases.
References:
- Allbaugh RA. Equine recurrent uveitis: A review of clinical assessment and management. Equine Veterinary Education. 2017 May;29(5):279-88.
- Kingsley NB, Sandmeyer L, Bellone RR. A review of investigated risk factors for developing equine recurrent uveitis. Veterinary Ophthalmology. 2023 Mar;26(2):86-100.
- Gerding JC, Gilger BC. Prognosis and impact of equine recurrent uveitis. Equine veterinary journal. 2016 May;48(3):290-8.
- Cook CS, Peiffer RL, Harling DE. Equine recurrent uveitis. Equine veterinary journal. 1983 Nov;15(S2):57-60.
