HEALING OF CORNEA GRAFTED WITH PROCESSED HUMAN AMNIOTIC MEMBRANE IN DOGS
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Date
2019-08-19
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD
Abstract
Cornea is an inimitable portion of the outer fibrous tunic of the eye. Due to its
transparent nature, it plays a major role in vision. Corneal ulceration or ulcerative
keratitis is a very common ocular emergency in companion animal practice.
Uncomplicated ulcers heal rapidly with minimal scar formation, whereas complicated
deep ulcers lead to corneal scarring or some time corneal perforation and synechia
formation resulting in impaired vision. Various modalities are reported for treatment
of corneal ulcers in humans, among which grafting with human amniotic membrane
(HAM) is reported to have minimal scar formation, neovascularization and fibrosis.
Few clinical cases had been reported in dogs too. This formed the basis of the present
study where corneal ulcers, following grafting with decellularised, sterilized, and
processed human amniotic membrane, was evaluated to study the healing effects of
the membrane in dogs.
The study was conducted in six clinical cases of dogs presented with
superficial to deep-and-extensive corneal ulcers. Healing of the cornea was studied in
all dogs after grafting with processed, decellularised and sterilized human amniotic
membrane.
All the dogs were treated with topical moxifloxacin eye drops prior to
surgery. Surgical debridement was performed under general anaesthesia using dry
sterile cotton buds, and with a lance blade. Ulcer bed and surrounding 1-2 mm area
was scarified and bed was cleaned for acceptance of the graft. Decellularised,
processed human amniotic membrane grafted as an onlay graft and secured in place
as an onlay graft using 10-0 polyamide suture. Topical instillation of moxifloxacin
was continued four times daily, flurbiprofen eye drops thrice daily until complete
healing and atropine eye drops once daily for five days in all the cases. Sutures were
removed on 14th post-operative day. Post operatively all the animals were evaluated
on 3rd, 7th, 14th and 30thdays.
Values of Schirmer tear test and number of blinks per minute were higher in
initial days, which later got reduced post-operatively. Also, there was progressive
reduction of corneal oedema, and improvement in corneal clarity. The superficial
corneal vascularization regressed, and none of animals had visible corneal vessels, by
the end of the observation period. All the animals regained corneal transparency
without scar at the ulcer site, except for a focal spot of haziness in three dogs. Corneal
pigmentation was not observed in four cases, but in two cases, they had corneal
pigmentation earlier with mild density before the surgery and their extent had
increased and density had become severe by the end of the study, without affecting
the vision of the animal. All the animals scored 2 (positive to all three tests and vision
graded normal) for visual function tests, on 30th postoperative day.
It could be concluded from the study that decellularised, processed human
amniotic membrane has epitheliotropic, anti-inflammatory, anti-angiogenic and antifibroblastic properties, and superficial to deep-and-extensive corneal ulcers in dogs
heal well and regain transparency when grafted with decellularised, processed human
amniotic membrane.