After so many veterinary webinars presented for WebinarVet by Ron Ofri, it can truly be said that he needs no introduction. This is the latest one and is as always at the highest level of teaching together with excellent clinical illustrations and videos.

He begins by attributing a quote from one of his mentors, Dr Dennis Brooks: 

‘Horses really have only 3 ophthalmic diseases’

  1. Corneal ulcers
  2. Uveitis
  3. Everything else!

This sets the scene for the webinar, which provides a comprehensive update on the first two.

Corneal Ulcers are classified as simple or complicated.

Simple ulcers are uncomplicated, superficial and without infection or cellular infiltration. The first of many world-class photographs illustrate an example. Left alone they won’t heal, very similar to the canine ‘boxer ulcer’, and what to do in this situation follows. A video demonstrates the use of a swab to debride loose epithelial tissue and a second video has the more high tech diamond burr debridement (DBD). Before and after photos show how effective these treatments are, and a reference in the literature confirms this. In 60 horses with non-healing ulcers treated with SBD, 92% healed on average in 15.5 days.

There is a recommendation to use bandage contact lens following the procedure, with a brief outline of the methodology and where to access the lenses.

Complicated ulcers are mostly traumatic in origin and infection (bacterial or fungal) is common, which may lead to corneal abscess or a melting cornea, the pathogenesis of which is summarised. A series of pictures show the various pathologies and colours associated with complicated ulcers –white, blue, red, and yellow, along with the diagnosis for each colour. These are best seen rather than described here, and in addition Ron provides a running commentary on each one.

Recommended procedures for an ulcer work are culture and sensitivity, (including mycology), and cytology. An interesting article demonstrates that the handle blade of a scalpel blade is the best technique for the collection of cytological specimens.

For the treatment of corneal ulcers install a lavage system (do not rely on the owners maintaining that they can apply drops regularly.), Consider gentamycin and anti-fungals, while treating uveitis with systemic and topical NSAIDs. Another recommendation is serum plasma, which cannot be overdosed and is cheap. It is administered every 1-2 hours until melting stops.   Atropine is essential and has potent analgesic properties, avoids synechiae and complications such as glaucoma. An eye shield is important.

There is a brief description of specialist surgical treatment of deep ulcers, emphasising conjunctival flaps. Third eyelid flaps and temporary tarsorrhaphy are NOT indicated. They do not fill a corneal defect, limit availability of topical medications and prevent monitoring.

The second part of the webinar begins with a revision of the anatomy of the uvea and some definitions of anterior and posterior uveitis. There is some background information on Equine Periodic Uveitis (ERU), previously referred to as Moon Blindness, and Periodic Ophthalmia. Prevalence in the USA and central Europe is common (up to 30% of horses in central Europe, 2-25% in the USA ) with vision threatened in 1-2 % of horses. It is less common in the UK, perhaps associated with less leptospirosis.

The important role of leptospirosis as a cause of ERU is described in some detail, and there are other less common potential triggers. Listed are a variety of these including bacteria, seven viruses, three parasites, blunt trauma, hypermature cataracts, systemic lymphosarcoma and intraocular melanoma. There is a predisposition for ERU in Appaloosa horses

The clinical signs of ERU are listed: 

  • Pain and blepharospasm
  • Conjunctival/scleral injection
  • Corneal oedema
  • Aqueous flare
  • Miosis
  • Hypotony
  • Hyphaema/hypopyon

Possible complications are: 

  • Cataract
  • Posterior synechiae
  • Corpora nigrum atrophy
  • Lens luxation
  • Vitreal degeneration
  • Retinal detachment
  • Glaucoma
  • Phthisis bulbi
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Following some clinical illustrations treatment is discussed. The aim is to preserve vision, decrease pain, and prevent or minimise recurrence. Treatment is often non-specific, to reduce and control inflammation regardless of cause. Aggressive and prompt treatment is essential, long term and likely life-long. Medical treatments described are topical prednisolone or dexamethasone, and topical NSAIDs such as diclofenac or nepafenac. Steroids and NSAIDs can be used simultaneously to achieve greater potency. 

Systemic NSAIDs (flunixin, phenylbutazone and aspirin) and prednisolone/prednisone are also frequently recommended. Mydriatic/cycloplegic treatment is given to effect and other considerations include the use of subconjunctival triamcinolone, tissue plasminogen activator in the anterior chamber, intravitreal injection of gentamicin, and the use of sustained cyclosporine implants.

If leptospirosis is present this will need treatment. However vaccination against leptospirosis may activate the immune response and worsen uveitis.

The final part describes Pars Plana Vitrectomy, with its associated benefits and complications in Europe and in the USA.

Loss of one eye is a severe handicap for horses, due to their laterally placed eyes and a small binocular field, and a couple of line diagrams illustrate the reasons. However, Ron makes a strong case that blindness is not a reason for euthanasia and you are invited to access www.blindhorses.org for further information.

This excellent webinar will greatly benefit anyone who treats horses, students, specialists in training and anyone else with an interest in veterinary ophthalmology. It is teaching at its very best.