[Application of the generalized additive model in determination of the retinopathy risk factors relation types for Tehran diabetic patients]

One of the most important complications of diabetes, is diabetic retinopathy that causes the blindness of 10,000 people every year. Different researches have been done on retinopathy risk factors in diabetic patients. This study was carried out to check the type of relationship between retinopathy risk factors and the condition of temptation it with generalized additive models. The study attempts to increase the quality of predicting the response variable and to reveal the non-linear and non-monotonic relationships between the response and the set of explanatory variables with generalized additive models. This cross-sectional study has been done on 367 diabetic patients who take part in assessment recall of retinopathy in Tehran. Entrants have been checked to determine their particulars, medical conditions and medicines. Finally has been used a data complex for fitting generalized additive models and binary logistic regression, including six continues explanatory variables: age, duration of diabetes, Body Mass index [BMI], hemoglobin A1C, cholesterol, systolic blood pressure and response variable, to the presence of retinopathy Fitting model has been done with mgcvR software. In this study 120 cases [33%] were retinopathy patient and 247 cases [67%] were not. Results of the generalized additive model were denoting that following factors have affected on retinopathy: duration of diabetes, hemoglobin and systolic blood pressure. Moreover, it has been mentioned that duration of diabetes with linear function, hemoglobin with function of degree four and systolic blood pressure with quadratic function was related to retinopathy. In addition to determination of retinopathy risk factors, it has been shown that generalized additive model can identify nonlinear relationship between variables. Therefore this model increases the quality of predicting response variable, with more information of the data relationships

Causes of Visual Impairment among Patients Referred to a Visual Rehabilitation Clinic in Iran

PURPOSE: Epidemiologic evaluation and investigating the causes of visual impairment in any society is a matter of concern and has a direct effect on the country's health care planning. In this study we describe causes of low vision and blindness in Iranian patients referred to rehabilitation clinics for taking vision aids. METHODS: In this cross-sectional study, visual acuity was classified based on best-corrected visual acuity in the better eye according to the World Health Organization definition (blindness, visual acuity [VA] < 20 / 400; severe visual impairment, VA < 20 / 200-20 / 400; mild to moderate visual impairment, VA < 20 / 60-20 / 200). The causes of blindness and low vision were determined using the 10th version of International Classification of Diseases based on the main cause in both eyes. To describe data, we used mean +/- SD and frequency. RESULTS: The study included 432 patients, 65% male, with a mean age of 43.6 +/- 25.5 years (range, 3 to 92 years). Mild to moderate visual impairment, severe visual impairment and blindness were present in 122 (28.8%), 196 (46.4%) and 105 (24.8%) of the patients, respectively. The main causes of visual impairment were retinal and choroidal diseases (74.5%), optic nerve and optic tract diseases (9.8%), vitreous and globe disorders (5.3%), congenital cataract (3.1%), and glaucoma (2.6%). The distribution pattern of the causes was similar in all age subgroups. CONCLUSIONS: Diseases of the retina and choroid are the main cause of visual impairment among patients referred to an academic visual rehabilitation clinic in Iran.

Early results of autologous cultivated limbal stem cell transplantation in total limbal stem cell deficiency

To report the early results of transplantation of autologous limbal stem cells cultivated on amniotic membrane [AM] in patients with total unilateral limbal stem cell deficiency [LSCD]. Four eyes of 4 patients with total unilateral LSCD confirmed with impression cytology underwent transplantation of autologous limbal stem cell cultivated on AM. At each follow up visit, a complete eye examination with special attention to recurrence or regression of vascularization, corneal opacification, and epithelial defect healing was performed. Digital imaging was performed at each follow up visit. Impression cytology was repeated in all cases after surgery. The patients were followed for 5-13 months. Visual acuity improved in all cases. Decrease in corneal opacification and vascularization was obvious in 3 cases with coverage of the cornea with corneal epithelium. Sectoral conjunctivalization was evident in these 3 cases, however the corneas were ready for transplantation. The procedure failed in one case with total corneal conjunctivalization. Transplantation of autologous stem cells cultivated on AM seems to be an effective way for total LSCD. More definite judgment needs longer follow up together with long-term results of corneal transplantation in these patients