Topical 1% cyclosporine eyedrops for the treatment of crystalline corneal dystrophy in dogs

Abstract

Background: Crystalline corneal dystrophy (CCD) is the most common type of corneal lipidic deposition in dogs. CCD
is a primary metabolic disorder of the corneal fibroblast featuring an accumulation of extracellular and intracellular lipid  deposits. Corneal lipid deposits create a corneal opacity and modify the interfibrillar collagen distance, inducing light  scattering. Corneal vascularization is not usually associated with the disease, but, in case of chronicity, cell death may  produce inflammation, and new corneal vessels are developed. To the best of the authors’ knowledge, this is the first  report of a medical approach for CCD treatment in veterinary medicine.

Aim: To evaluate the efficacy of topical 1% cyclosporine eyedrops (1% CsA) for the treatment of CCD in dogs.

Methods:  Medical records of dogs with CCD were retrospectively reviewed (2009–2020). Corneal opacification description (COD)  [size (mm), depth, and opacification degree (0–3)] was evaluated at 0, 3, 6, 9, 12, and 15 months postinitial diagnosis.  Dogs were classified into three groups: the control group (G₀ ), the group receiving topical 1% CsA once per day (G₁ ),  and the group receiving topical 1% CsA twice daily (G₂).

Results: Ninety-two client-owned dogs (163 eyes) of different  breeds, ages, and gender fulfilled the inclusion criteria. When compared to G₀ , where the eyes significantly increased COD (p < 0.001), G₁ and G₂ significantly decreased COD (p < 0.001). In fact, the probability of reducing COD was about three times higher in G₂ than in G₁ , being nearly the same  for the right [odds ratio (OR) = 2.94; 95% confidence interval (95% CI) = 0.55–15.78] and left eye (OR = 2.92; 95% CI =  0.49–17.26). In addition, for each additional month of treatment in G₂ , the probability of reducing COD increased  significantly (OR = 1.12; 95%CI = 1.00–1.26 for the right eye and OR = 1.16; 95%CI = 1.02–1.32 for the left eye).  

Conclusion: Long-term treatment with topical 1% CsA eyedrops significantly improved CCD in dogs, being the   probability of reducing COD higher when applying the treatment twice daily.