Role of anti-oxidant enzymes superoxide dismutase and catalase in the development of cataract : study of serum levels in patients with senile and diabetic cataracts.

Cataract is a universal phenomenon in old age and the most common cause of blindness worldover. Oxidative stress is believed to be a key factor in the gradual loss of transparency of lens. Free radicals formed result in derangement and opacification of lens fibres. Superoxide dismutase, catalase and glutathione peroxidase are major anti-oxidant enzymes, which protect against free radicals. The purpose of this study is to evaluate the role of anti-oxidant enzymes - superoxide dismutase and catalase in the development of cataract in senile and diabetic persons. Serum levels of major anti-oxidant enzymes-superoxide dismutase and catalase were estimated in 20 patients with diabetic cataract, and matched with another 20 patients of senile cataract taken as control. Estimation of superoxide dismutase was done by improved spectrophotometric assay based on epinephrine auto-oxidation at 480nm, while catalase estimation was done by the method of Hugo Aebi. The mean serum levels of superoxide dismutase and catalase were lower as age increased. These enzymes were also significantly lower in diabetic cataracts (9.13 and 16.42 units/ml) as compared to senile cataracts (25.30 and 57.27units/ml). Oxidative stress is one of the major factors contributing to cataract formation. In diabetics where there is increased oxidative stress, the serum levels of the major anti-oxidant enzymes decrease, which lead to early cataract formation. It may be concluded that oxidative stress is an important factor in the development of diabetic cataracts and anti-oxidants may have a role in decreasing the incidence of cataract.

Amniotic membrane transplantation in ocular surface disorders.

In this prospective study, 81 eyes of 70 patients diagnosed with various ocular surface disorders were enrolled to document the use of amniotic membrane transplantation in various ocular surface disorders. Detailed history and ocular examination was done. Ocular photographs and consent from all patients were taken. Fluorescein staining and impression cytology was done preoperatively and postoperatively in selected cases. Amniotic membrane was prepared from the placenta of a donor (consent taken and negative for infectious disorders), after separating amnion from chorion. It was washed with antibiotic solutions, transferred over nitrocellulose paper and stored in Dulbecco's modified Eagle's minimum essential medium at -80 degrees C. Recipient bed was prepared by removing the fibrovascular pannus and necrosed conjunctiva. Amniotic membrane was transplanted with the epithelial side up and sutured. Sixty-four eyes had good result by clinical evaluation or impression cytology findings, 5 eyes later required limbal stem cell culture and transplantation. All the 3 eyes had failure of the fornix reconstruction and 5 eyes had recurrence of the pterygium. Amniotic membrane provides lower recurrence rate in cases of recurrent pterygium. Alkali injuries are more dangerous but showed good response to amniotic membrane transplantation combined with limbal autografting or ex-vivo expansion and later transfer. Initial proper assessment of limbal involvement, conjunctival necrosis and corneal involvement is the key to the management of acute cases. Contracted sockets showed no improvement. Shield ulcers and persistent epithelial defect and ocular surface defects secondary to tumour excision showed excellent results.