SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
reduction in inflammation is via induction of apoptosis of keratocytes in the anterior stroma and this seems to contribute to the local immune response . Famose [ 2014 ] also described very encouraging results of CXL in his study in dogs and advocates that CXL could be used as the initial treatment for ulcerative keratitis .
CXL has been shown to have great success in humans , cats and dogs for ulcerative keratitis and a study by Hellander-Edman et al has shown that equine stromal lesions can also be managed very successfully with this technology . Equine corneal lesions are the most common eye problem in the horse and can cause varying degrees of visual impairment or even blindness . In the cases reported by these authors the patients had the classic equine ulcerative keratitis with leukocyte infiltrates surrounding the ulcers and some showed corneal melting . Most stromal lesions in horses have an intact epithelium . They have resulted in inoculation of infection into the stroma and subsequent healing of the covering epithelium . The CXL was performed in sedated standing horses . The authors noted that “ horses showed improvement within 3 days and all seemed to follow the same progression . This included the reduction of inflammatory signs , including reduced signs of ocular pain , decrease in corneal oedema and ciliary injection and less aqueous flare and inflammatory cells in the anterior chamber . The stromal melting had stopped when re-examined the day after treatment . In 2 – 4 days , a granular appearance of the denuded stromal tissue could be observed and in some cases a rejection of necrotic mucoid tissues followed . Ingrowth of blood vessels to the ulcerated area and regeneration of the corneal stroma and reepithelialisation could be observed . Eight of nine eyes became fluorescein negative in 13.5 days ( median time ; range 4 – 26 days ) after CXL ”.
One of the significant advantages of the use of CXL for equine stromal ulcers appears to be the ability to stabilise the melting component quicker [ overnight ] which may be very beneficial when labour intensive medications and anti-protease medication is given frequently to control enzymatic degradation of the corneal stroma . Pain is also improved .
Contra indications
CXL can lead to Herpes virus exacerbation in humans . In a report by Famose CXL did not lead to any reactivation in 2 FHV positive cats but there were no signs of active disease at the time of CXL treatment . The current recommendation is that CXL should not be used in Feline patients with active FHV keratitis . CXL is also contraindicated in corneas thinner than 400ųm as this may lead to endothelial damage or damage to intraocular structures .
Adverse effect
Clinical studies indicate that CXL is a safe procedure with few major complications . A few adverse effects have been documented and these can include corneal haze , scarring , presence of infectious and non-infectious stromal melting or further progression of the ectasia [ corneal distortion ]. Infections seem to be related to the fact that the epithelium has been removed . Endothelial failure may occur but is limited when CXL is used on corneas greater than 400 µ m thick . Accidental illumination of the limbal stem cells can permanently damage them .
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