Noninvasive diode laser-an effective and safe treatment of iris cysts in 46 eyes of 35 horses.
Authors: Stas Emanuël K L, Hermans Hanneke, Slenter Inge J M, Veraa Stefanie, Ensink Jos M
Journal: Equine veterinary journal
Summary
# Diode Laser Treatment for Equine Iris Cysts: Efficacy and Safety Iris cysts in horses present a clinical paradox: whilst often incidental findings, they can trigger problematic behavioural signs including shying, performance loss and head-shaking, alongside corneal oedema. This 2023 retrospective analysis from Utrecht University examined diode laser ablation across 46 eyes in 35 horses treated between 2008 and 2020, using ophthalmic examination, ultrasonography, and long-term follow-up via owner questionnaire and photographic re-evaluation. Short-term results were encouraging, with 76% of treated eyes showing good cyst size reduction within 24 hours, though polycystic eyes, thick-walled cysts and those associated with hyperplastic corpora nigra responded less favourably (odds ratios of 0.381, 0.139 and 0.081 respectively). Complications were minor—mild reactive uveitis occurred in 17% of eyes—and at median 19-month follow-up, 93% of cases showed diminished or resolved clinical signs, with only 12.5% recurrence on photographic assessment and 83% of owners recommending the procedure. Pre-operative ultrasonographic assessment is therefore valuable for case selection and surgical planning, positioning diode laser as a safe, minimally invasive option for managing symptomatic iris cysts where medical or behavioural signs justify intervention.
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Practical Takeaways
- •Diode laser is an effective noninvasive treatment option for iris cysts in horses with low recurrence risk and good long-term outcomes in most cases
- •Presurgical ultrasonography should be used to assess cyst characteristics (thickness, number, presence of hyperplastic corpora nigra) to predict treatment success and guide surgical planning
- •Owners can be counseled that 83% of cases show good long-term results with diminished clinical signs, though some cyst types may respond less favorably
Key Findings
- •Diode laser treatment resulted in good cyst size reduction in 76% of eyes (35/46) at one day post-treatment, with minor complications in 17% (8/46 eyes with mild reactive uveitis)
- •Long-term clinical signs diminished or disappeared in 93% of cases at median 19-month follow-up, with 83% of owners recommending the treatment
- •Polycystic eyes, thick-walled cysts, and hyperplastic corpora nigra showed significantly less satisfactory treatment response with odds ratios of 0.381, 0.139, and 0.081 respectively
- •Recurrence rate was low at 2/16 cases (12.5%) based on photographic re-evaluation at median 32.5-month follow-up