A two-year-old male crossbred terrier (Fig. 1) ispresented with an acutely painful left eye. This is histhird visit to the surgery over the last two weeks andhis persistent corneal ulceration has failed to respondto changes in topical antibiotics.

QUESTIONS

1.Describe the abnormalities in Fig. 1.2.What are the possible causes of persistent or

recurrent corneal ulceration in the dog?3.What are the next steps in diagnosis?4.What is the treatment?

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Lorna J Newman BVM&S CertVOphthal MRCVSEYE-VET, 59 MAIN STREET, FRODSHAM, CHESHIRE. WA6 7DF

Self-assessment

Fig. 1.

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ANSWERS

1. Fig. 1 is a close-up of the left eye. The globe isrotated downwards. The lateral canthal area isslightly wet, perhaps indicating increasedlacrimation, but the appearance of the tear filmand corneal reflex are normal. There ishyperaemia of the conjunctival vessels. There is acentral superficial corneal ulcer. The upper eyelid has several long distichic lashes present towardthe lateral canthus.

2. Causes of superficial refractory cornealulceration in the dog are too numerous to listexhaustively. The most frequent causes howevercould be arbitrarily split into groups relating toinitiating factors:

� Primary corneal conditions of which the twomost common are:� superficial chronic corneal epithelial defect

(SCCED), otherwise known as Boxer orindolent ulcers, perhaps the largest group ofnon healing ulcer; typically irregular in shapewith a non-adherent lip of epithelium whichfluorescein stain will underrun; occurs inmiddle aged dogs with certain breedpredispositions, notably the Boxer; slowhealing associated with non-adherence of theregenerating epithelial layer

� corneal oedema/long-standing severe oedemaoccurring usually from age-relateddegeneration of the endothelial cell layer canresult in formation of bullae, which mayrupture forming small localised ulcers or canlift the epithelium from the stroma, formingerosions; can be slow to heal and bullae oftencontinue to form

� Conditions associated with the pre-ocular tear

film - keratoconjunctivitis sicca (dry eye) caninvolve ulceration, as can tear film mucindeficiencies, which reduce the stability of thetear film

� Lid function disruption

� neurotrophic keratitis can involve ulcerationdue to loss of corneal innervation and reducedblink response, often resulting in cornealdegenerative change and ulceration

� lagophthalmos (overly-large palpebral fissure),which leads to the inability to close the eyelidscompletely and facial nerve paralysis, whichdamages the normal blinking mechanism, cancause ulcers, again due to corneal exposureand drying

� Conditions associated with abnormal lid

structure or abnormal cilia within the lids suchas entropion and ectropion in all of their many,often breed-related forms. Careful examinationof the patient, including examination with alowered head carriage, is needed to assess thisfully. Corneal ulceration may result fromtrichiasis, which is any contact from lid hairsincluding those from facial folds, lid margindamage or facial mask slip

� Distichiasis and ectopic cilia are abnormal ciliaarising from the Meibomian glands in the lidmargin, and these cilia can also cause ulceration.

3. The first step in diagnosis is a full ophthalmicexamination, which in this case ruled out manyof the possible differential diagnoses. A Schirmertear test showed a tear level of 20 mm wetting in30 seconds in the left eye, compared with 18 mmin 60 seconds in the right eye. Fluorescein dyewas administered and the cornea examined atthe time of staining and a few minutes afterstaining to assess whether under-running waspresent, which it was not.

Intense blepharospasm, which resolved after theadministration of local anaesthetic drops, wasnoted, indicating a superficial cause for thediscomfort. Lid function and structure were alsoassessed and found to be normal, apart from thepresence of distichic lashes. The distichic lashespresent did not contact the site of the cornealulceration at any time during the blink response.

Eversion of the upper lid revealed an ectopiccilium, the position of which correspondedwith the ulcer site. In this dog, the lashes arepigmented and can be visualised, helped by slitlamp magnification (Fig. 2). In individualswhere the hairs are poorly pigmented or onlypartially erupted, visualisation can be difficultand the higher magnification of a surgicaloperating microscope under general anaestheticcan be required.

4. Treatment consists of localised complete excisionaround the hair and follicle (Fig. 3). Concurrenttreatment of distichia by the surgeon’s preferredmethod could be carried out simultaneously.This is usually by electrolysis or cryotherapy. Thecyclical nature of hair growth should bediscussed with the owner and the fact that ciliamay therefore appear in previously unaffected

Self Assessment

Fig. 1.

areas. The problem of distichiasis and ectopic ciliacan therefore be recurrent. Antibiotic cover usingbroad-spectrum topical antibiotic drops shouldalso be administered until the ulceration heals.

DISCUSSION

Distichia and ectopic cilia arise from follicles withinthe Meibomian glands in the lid margins. Distichiaemerge from or adjacent to the gland orifices alongthe lid margin (the so-called grey line). Ectopic ciliaemerge from the palpebral conjunctiva and impingedirectly onto the cornea. They arise as single lashesor multiple lashes in clumps and usually causelacrimation, intense blepharospasm and secondarycorneal ulcers. Distichia on the other hand can havevariable clinical significance.

In a patient where distichia seem to be causingacute discomfort and ulceration, the presence ofectopic cilia should also be suspected. This may be particularly true in certain breeds, for examplethe Bulldog, where ectopic cilia seem to occurmore frequently.

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Fig. 2.

Fig. 3.