EQUINE | Equine Disease Update
common. These ulcers are very similar to those in small
animals – Spontaneous Chronic Corneal Epithelial
Degeneration [SCCED]. The lesion is also usually
unilateral, centrally or paracentrally located and a
halo of loose epithelium is visible around the lesion.
The affected eye usually has little neovascularisation
present, some oedema is usually seen around the
lesion and the eye is painful. There may be bouts of
intermittent healing. The non-adherent epithelial
edges can be identified by infiltration of fluorescein
underneath the epithelium surrounding the erosion.
This occurs due to the decreased adhesion sites
between migrating epithelial cells as well as lack of
adhesions to the basement membrane [decreased
density of hemidesmosomes]. Recently the presence
of a hyalinised membrane has been shown to further
hinder adhesion of the epithelial layer. A thorough
clinical investigation looking for foreign bodies,
ectopic cilia or any eyelid abnormalities is essential.
The treatment approach for these cases is to ensure
there is no mechanical cause present [foreign body,
cilia etc].
discomfort in the first 1-2 days.
3. Grid keratotomy - A grid keratotomy is performed
by initially debriding the epithelium off the
cornea with a blade and then creating a hatched,
grid pattern across the entire erosion [using the
bevel edge of a needle] through the basement
membrane, which exposes epithelial cells to
stromal collagen type I, which is believed to
promote more effective basal cell attachment.
A potential negative complication could be the
extension or entrapment of infection into the
superficial stroma. An equine soft contact lens
can also be applied after this procedure and
medicated as in [2] above.
4. Superficial keratectomy involves the complete
removal of the basement membrane and anterior
stroma and one relies on second intention healing.
In all cases appropriate topical medications
[antibiotics and atropine] and oral NSAIDs with
or without a soft contact lens should be used.
Corneal re-epitheliasation is expected to be about
0.6mm/day. The data showed that:
The options include:
1. Mechanically debriding the sloughing edge with a
cotton bud or more abrasive instrumentation.
2. Diamond head burr [Algerbrush] debridement
which removes redundant epithelium in a
controlled and uniform manner as well as the
hyaline zone lining the base of the lesion. This is a
newer treatment modality that has great potential
as it can be performed under standing sedation,
is relatively safe to perform and success rates
are good. An equine contact lens and topical
medication with Tobrex or Vigamox, Atropine
drops and morphine drops can be added as
an adjuvant preparation to assist in reducing
Treatment method
Healing time
Debridement only
15.3 days
Grid keratotomy
16 days
Superficial Keratectomy 23 days
% Success
63%
78-80%
78-80%
Ref: Lassatine-Utter et al
The data suggest that these surgical procedures are
indicated but should only be performed following
failure of the ulcer to heal after epithelial debridement
References:
Lassatine-Utter ML, Cutler TJ, Michau TM, Nunnery CM. Treatment of nonhealing
corneal ulcers in 60 horses with diamond burr debridement (2010–2013). Vet
Ophthalmol 2014;17 Suppl 1: 76–81. Michau T, Schwabenton B, Davidson M, et al. Su-
perficial, nonhealing corneal ulcers in horses: 23 cases (1989–2003). Vet Ophthalmol
2003; 6:291–297.
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