THE HAIRY EYEBALL - LIMBAL DERMOID

1. THE HAIRY EYEBALL-LIMBAL DERMOID DR.PAWAN N. JARWAL, DR.KINJAL H. DESAI, THIRD YEAR RESIDENTS DEPARTMENT OF OPHTHALMOLOGY S . S. G. HOSPITAL,VADODARA

2. INTRODUCTION: The estimated worldwide incidence of limbal dermoid is 1 per 10,000 to 3 per 10,000. Limbal dermoid are benign congenital tumours that contain choristomatous tissue (tissue not found normally at that site ). They appear most frequently at the inferior temporal quadrant of corneal limbus and remain localised mostly to the superficial layer of the cornea and sclera. They may contain a varity of histologically aberrant tissues , including epidermal appendages, connective tissue,skin,fat,sweat gland,lacrimal gland ,muscle ,teeth,cartilage,bone,vascular structure and neurologic tissue including the brain. Malignant degeneration is extremely rare .

3. Limbal dermoid are thought to arise from an early embryological anomaly (occurring at 5-10 weeks gestation)resulting in metaplastic transformation of mesoblast between the rim of optic nerve and surface ectoderm . Limbal dermoid are present at birth but may not be recognized until the first or second decade of life . T hey may appear to enlarge as the body mature.

4. MATERIALS AND METHODS: A 30 year old man presented with a mass in his left eye that was present since birth and gradually increased in size . He did not have pain, but the mass caused vision defect, sensation of presence of a foreign body, discomfort on blinking and cosmetic disfigurement. There was no family history of similar lesion.

5. Examination revealed a solid reddish-yellow, round, mass measuring 5x5x3 mm having rough surface with partly keratinized epithelium and hair involving the infero-temporal limbus and cornea .No associated regional or systemic abnormalities were found .Visual acuity was 6/6 in right eye and 6/60 in left eye. The finding on slit-lamp examination,fundoscopy and ocular USG were within normal limit and IOP was normal .

6. After obtaining consent from patient the lesion was dissected off the cornea and limbus under local anaesthesia with meticulous attention for preservation of normal tissue. A cleavage plane was fashioned, and the dermoid was removed from the cornea first, with movement towards the limbus. Removed section was sent for histopathologic examination where section showed histology of flattened epidermis. Dermis contained occasional sebaceous gland lobule with hair follicle and adnexal glands in a loose collagenised tissue.

7. The surgical result was very reasonable from a cosmetic result, and the patient recovered well from his symptoms .As expected there was little improvement in visual acuity after surgery because of the amblyopia and induced astigmatism.

8. DISCUSSION : Anatomically limbal dermoids have been classified into three grades. This form of grading allows clinicians to take a more stepwise approach to the clinical and surgical management of such lesion. * Grade 1 limbal dermoid are superficial lesion measuring less than 5 mm and are localized to limbus . Such lesion may lead to development of anisometropic amblyopia ,with slow growth resulting in oblique astigmatism and flattening of cornea adjacent to the lesion. *Grade 2 limbal dermoids are larger lesion covering most of the cornea and extending deep to the stroma down to Descemet's membrane without involving it . *Grade 3 limbal dermoids ,the least common of all the presenting dermoids , are larger lesion covering the whole cornea and extending through the histological structures between the anterior surface of the eye ball and the pigmented epithelium of iris .

9. Visual morbidity in limbal dermoid mainly results from encroachment of the lesion into the visual axis , development of astigmatism or formation of lipid infiltration of the cornea, which obstructs the visual axis . Large Limbal dermoid can be cosmetically disfiguring . In some cases staphyloma formation adjacent to dermoid has been reported and may be associated with spontaneous perforation of cornea or sclera. A varity of surgical techniques has been described in the literature , ranging from simple excision to lamellar and/or penetrating keratoplasty with relaxing corneal incision, depending on the grade of lesion. Depth,size,and site of such lesion are critical factor .Other techniques include corneal-limbal scleral donor graft transplantation and surgical resection followed by reconstructive multi-layered amniotic membrane transplantation.

10. Conclusion : Treatment of limbal dermoid may consist of periodic removal of irritating cilia, topical lubrication to prevent foreign body sensation, or excision of the lesion if it causing significant cosmetic disfigurement or interfering with vision . Attempts at complete removal are unnecessary because lesion may extend into the deeper structure of the eye and risk of perforation increase if attempts are made to remove lesion completely. If a deep excision is necessary, then a lamellar keratoplasty can be performed to reinforce the site of excision.

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