Surgical Management of Corneal Sequestrum in a Cat.
A two year old persian cat was presented with history of abnormal dark spot on the cornea. Physical and ophthalmic examination like schirmer tear test, fluorescein dye test and slit lamp biomicroscopy revealed chronic keratitis and corneal sequestrum. Partial keratectomy followed by pedicle bulbar conjunctival graft was undertaken and the animal recovered uneventfully after surgery with no recurrence.
Keywords: Conjunctival graft; corneal sequestrum; feline; keratectomy
Corneal sequestrum is a disease characterized by collagenolysis and necrosis of collagenous stroma leading to formation of amber to black pigmentation in anterior stroma (Startup, 1988).
The etiology and pathophysiology of feline corneal sequestrum (FCS) is unclear (Cullen et al., 2015). Chronic corneal ulceration, entropion, decreased corneal sensitivity and some infectious agents like feline herpes virus-1 have been considered as triggering factors in formation of corneal sequestrum (Williams and Kim, 2009).
History and Diagnosis
A 2 year old persian cat weighing 3 kg was presented with history of blackish discolouration of central part of cornea (Fig. 1). Ophthalmic examination revealed corneal sequestrum. Fluorescin dye test was performed which stained the periphery of black coloured part of cornea. The excised sequestrum was collected in 10% formalin and sent for histopathological examination stained by haematoxylin and eosin.
Treatment and Discussion
General anaesthesia was induced with Diazepam @ 0.2 mg/kg and Propofol @ 4 mg/kg intravenously and maintained with 2.5% Isoflurane in oxygen with Boyles anesthetic apparatus. The cat was placed on left lateral recumbency, so that the right eye top most position and head was slightly elevated above the table. Under magnification of operating microscope, temporary stay sutures were placed with non absorbable silk 3-0 around the conjunctiva to position the eyeball in central position. The eye was lavaged with sterile water and 0.5% Proparacaine was instilled topically to desensitize the cornea. The periphery of corneal lesion was incised with bard parker blade size 11 to a depth of about 0.3-0.4 mm. The edge of lesion was grasped with corneal forceps and lesion was separated from underlying collagenous stroma by careful dissection. The stromal dissection was continued and completed till the lesion was removed creating a corneal defect (Fig. 2). The pedicle bulbar conjunctival graft was harvested from 12 o' clock position by dissecting with tenotomy scissors. The ventral end of graft was trimmed by scissors to confirm with the ventral edge of the corneal defect and was apposed with corneal defect by 8-0 simple interrupted monofilament absorbable sutures (Fig. 3). Topical antibiotic (Higati (a)-Gatifloxacin), artificial tears (Hicool (a)-Hydroxypropyl Methyl Cellulose) and anti-inflammatory (Penfen (b)-Flurbiprofen) eye drops were instilled three times a day for 14 days and Syrup Cephalexin @ 20 mg/kg orally BID for 5 days was given post-operatively. The owner was advised to apply Elizabethan collar around the neck to prevent rubbing of eyes. The corneal defect healed after one month with minimal scarring.
The histopathological examination of sequestrum revealed degenerative changes and coagulation necrosis of collagenous stroma with a surrounding zone of inflammatory cells, macrophages, plasma cells and giant cells. Several therapeutic options are available for management of feline corneal sequestrum (Morgan, 1994). At first the underlying cause should be identified and corrected. Surgical treatment is done to cease the progression of lesion and promote corneal healing (Gelatt and Brooks, 2011). Superficial keratectomy as a single surgical procedure is done, when the lesion affects only 50% of stromal depth. When more than 50-70% of stromal depth is affected, then grafting techniques like conjunctival grafting, corneoconjunctival transposition (CCT) or biomaterial grafting is done (Goulle, 2012). In our case more than 50% of stromal layer was affected, hence partial lamellar keratectomy followed by pedicle conjunctival grafting was done to support the cornea. Post operative opacification varies greatly depending upon the selected surgical technique. Superficial keratectomy alone and combined with conjunctival grafting has been associated with recurrence of sequestrum. (Featherstone and Sansom, 2004). In our case the lesion was in central cornea and minimal scarring was noticed post-opertively. Moreover the case was followed up for 4 months and no recurrence of sequestrum was noticed.
Cullen, C.L., Wadowska, D.W. and Singh, A. (2005). Ultrastructural findings in feline corneal sequestrum. Vet Ophthalmol. 8: 295-03.
Featherstone, H.J. and Sansom, J. (2004). Feline corneal sequestra: a review of 64 cases (80 eyes) from 1993-2000. Vet Ophthalmol. 7: 213-27.
Gelatt, K.N. and Brooks, D.E. (2011). Surgery of the cornea and sclera. In: Gelatt KN and Gelatt JP, (eds). Veterinary Ophthalmic Surgery, 1st edn, Saunders Elsevier, San Francisco, pp 191-236.
Goulle, F. (2012). Use of porcine small intestinal submucosa for corneal reconstruction in dogs and cats -106 cases. J Small Anim Pract. 53: 34-43.
Morgan, R.V.(1994). Feline corneal sequestration - A retrospective study of 42 cases (1987-1991). J Am Anim Hosp Assoc. 30: 24-69.
Startup, F. (1988). Corneal necrosis and sequestration in the cat - A review and record of 100 cases. J Small Anim Pract. 29: 476-86.
Williams, D.L. and Kim, J.Y. (2009). Feline entropion: a case series of 50 affected animals (2003-2008). Vet Opthalmol. 12: 221-26.
(2.) Post Graduate Scholar
(3.) Post Graduate Scholar and Corresponding author.
(a) - Brand of Hicare Pharma, Chennai
(b) - Brand of Atco Laboratories Ltd., Karachi
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|Title Annotation:||Short Communication|
|Author:||Shafiuzama, Mohamed; Narayanan, Krishnaveni; Babu, M.S. Sabarish|
|Date:||Jul 1, 2016|
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