Compromised ocular surface defence caused by malfunction of lids or tear film, nerve damage, corneal infection and chronic inflammation may lead to persistent epithelial defects and corneal stromal melting. Persistent corneal epithelial defects caused by primary or secondary ocular surface disorders may be difficult to treat and usually induce prolonged inflammation of the ocular surface, loss of corneal stem cells, and destruction of the epithelial basement membrane, resulting in corneal scarring, neovascularisation, and decreased vision.1,2 Conservative treatment of epithelial defects with stromal ulceration consists of treatment modalities such as continous pressure patching or therapeutic soft contact lenses with preservative-free lubricants and punctum occlusion.3 Patients failing to respond to a medical approach may eventually require a surgical procedure like tarsorraphy or penetrating keratoplasty.4,5 Lee and Tseng6 initially proposed the use of human amniotic membrane for the treatment of epithelial defects with stromal ulcers that remain recalcitrant to conventional treatments. Subsequently, successful applications of amniotic membrane transplantation (AMT) in cicatricial eye diseases, pterygium surgery and ocular surface reconstruction were described.7,8,9 Amniotic membrane consists of a thick basement membrane and an avascular stroma that contains a high concentration of basic fibroblast growth factor, basement membrane components, and presumed trophic factors. The stromal matrix of the amniotic membrane is known to have the ability to exclude the inflammatory cells and promote healing.6 The aim of this study was to investigate the effect of preserved human amniotic membrane in the treatment of nonhealing corneal ulcers and also investigate the timewise effects on corneal sensitivity, tear function, and impression cytology parameters.

A total of 10 eyes of 10 patients (seven males; three females) aged between 25 and 76 years (mean: 54.5±16.5 years) underwent preserved amniotic membrane transplantation between April 2000 and April 2001 for persistant corneal epithelial defects with stromal ulceration. All patients were initially treated with removal of toxic topical antibiotics, lubrication, autologous serum eye drops and with a bandage contact lens/pressure patching for at least 8 weeks. A total of 44 patients diagnosed with corneal ulcers owing to infectious keratitis, alkali injury, diabetic neuropathy, or dry eyes responded to the above-mentioned conventional approach during the same period. Tarsorraphy was suggested when these techniques were unsuccessful. The 10 patients in this series did not opt for a tarsorraphy procedure. None of the patients had a history of atopy, Stevens–Johnson syndrome, thermal or radiation injury, or contact lens use for refractive purposes before amniotic membrane transplantation. Three patients had type II diabetes mellitus, which was not under good control (a fasting blood glucose level of greater than 140 mg/dl and a glycosylated haemoglobin level of greater than 7.8%) throughout this study. Patients with herpe simplex keratitis received oral acyclovir 1000 mg/day as well as 60 mg/day of prednisolone for 1 week, followed by gradual tapering of oral corticosteroids. Patients with postinfectious keratitis received sufficient systemic and topical antibiotics/antifungals to eradicate the causative organisms. None of these patients had clinical or microbiologic signs of acute corneal infection at the time of amniotic membrane transplantation. The 10 patients in whom the corneal epithelial defects did not close despite all mentioned attempts received amniotic membrane transplantation. Two patients had herpetic and three others had postinfectious corneal ulcers. The ulcers were because of alkali burn in two eyes and were of neurotrophic nature in two eyes. One other eye had a persistant epithelial defect on the corneal graft after penetrating keratoplasty. Clinical features of the patients are summarised in Table 1 and Table 2. Routine ophthalmic examinations consisted of best-corrected visual acuity (BCVA) measurements, anterior segment photography, and slit-lamp examination. Corneal thickness was evaluated using biomicroscopy or ultrasonic pachymetry (Biomed, France) before and after the operation at each visit. Stromal thickness was recorded and compared with the thickness of the same area after the operation only when the surgical area was completely epithelialised. A stromal ulcer with keratolysis exceeding 50% of corneal stromal thickness was regarded as a deep ulcer in this study. Increase in stromal thickness of the eyes at the last follow-up as observed by careful biomicroscopy and anterior segment photography was defined as ‘stromal gain’. The patients underwent ocular surface examinations including corneal sensitivity measurements, tear film break-up time (BUT), Schirmer test, and conjunctival impression cytology. The patients were required not to have instilled their medications at least 6 h prior to these examinations. All examinations were performed by the same researcher. An informed consent about the procedures was obtained. Tear function and corneal sensitivity measurements were performed before amniotic membrane transplantation, with epithelisation, attainment of resolution of the membrane, and at the last follow-up. Corneal sensitivity was measured using a Cochet-Bonnet aesthesiometer. The measurements were begun with the nylon filament fully extended. The tip of the nylon filament was applied perpendicular to the surface of the corneal lesion making certain not to touch the eyelashes and was pushed until the fibre's first visible bending. The length of the fibre was gradually decreased until a blink reflex was observed. The length was recorded in units of millimetre. A corneal sensitivity measurement of less than 50 mm was regarded as low corneal sensitivity in this study.

Table 1 Clinical features of the patients
Full size table
Table 2 Amniotic membrane transplantation (AMT) results
Full size table

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