Immune-mediated keratitis (IMMK) is typically described as chronic, nonulcerative corneal opacity with minimal discomfort in the absence of intraocular inflammation. North American publications describe minimal blepharospasm, rare corneal ulceration, and no uveitis. In the UK, the epithelial and anterior stromal forms have been inconsistently associated with slight blepharospasm. Corneal ulceration is rarely described in either geographic location, but it is reported occasionally in the mid-stromal and endothelial forms in both countries associated with ruptured corneal bullae, which in turn can cause discomfort. To the authors’ knowledge, uveitis has not been described as a clinical feature of IMMK. There is limited literature regarding equine IMMK in Europe. This retrospective case series aimed to assess the prevalence of blepharospasm, corneal ulceration, and uveitis in horses and to determine these conditions’ impact on the outcome of IMMK cases in the UK and Finland.
Case Study on IMMK in Horses
Researchers evaluated clinical records of 94 horses with IMMK. The UK and Finland populations were comparable; therefore, descriptive statistics were performed on combined data on subtypes of IMMK and clinical features. Odds ratios (OR) and confidence intervals (CI) were calculated for impact of blepharospasm, ulceration, or presence of uveitis on the outcome of enucleation and treatment duration.
IMMK subtype was classified as 10/94 (10.6%) epithelial, 50/94 (53.2%) anterior stromal, 14/94 (14.9%) mid-stromal, 4/94 (4.25%) endothelial, and 16/94 (17.0%) unrecorded. After excluding three horses with incidental corneal ulceration, blepharospasm was documented in 34/91 (37.4%), corneal ulceration in 26/91 (28.6%), and signs of uveitis in 23/91 (25.3%) horses. Increased odds of enucleation were significantly associated with the presence of blepharospasm (OR 5.5, 95% CI 1.6–19.4, p = 0.008) and signs of uveitis (OR 8.9, 95% CI 2.6–30.8, p < 0.001) but not corneal ulceration. The presence of blepharospasm, corneal ulceration, or uveitis did not significantly alter the odds of ongoing medication.
Bottom Line
The clinical features of IMMK were similar in the UK and Finland but differed from how the condition is described in the U.S. Blepharospasm, corneal ulceration, and signs of uveitis can occur with IMMK; presence of blepharospasm and uveitis increase the odds of enucleation.
https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.14213
Related Reading
- Corneal Cross-Linking to Treat Ulcerative Keratitis in Horses
- Disease Du Jour: Equine Recurrent Uveitis
- AAEP Health Coverage: Novel Drug (SOCS1-KIR) to Treat Uveitis in Horses
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