Abstract
Abstract: :
Purpose: The AlphaCor artificial cornea, (Chirila keratoprosthesis), has been evaluated in human patients since 1998. This study was conducted in order to review outcome data throughout the study period so as to evaluate trends and identify factors that may increase or reduce the risk of complications. Methods: Detailed outcome data were collected at every visit for analysis using the statistical package SPSS. At each month's end, data were re-analysed and that 'frozen' data set stored, so that retrospective analysis of trends over time could be performed. Data collected included pre-operative profile including original aetiology, number of prior grafts, intra-ocular lens status; follow-up period; complications reported, including melts of surrounding stroma and depositions within the device optic, glaucoma and infections; uncorrected and corrected visual acuity at each interval and all current medications. Results: To end November, 2002, 47 devices had been implanted into 43 eyes of 43 patients; 4 patients received a second device following deposition within the device optic. Follow-up at this time ranged from 2 weeks to 49 months, mean 15.5 months, with a trend to increasing mean follow-up time during 2002 followed by a fall as the rate of device implantations increased. Significant factors affecting the incidence of stromal melts included a history of prior ocular herpes simplex, which increases the risk and use of topical medroxyprogesterone, which appears to reduce the risk. Trends in melt incidence rose and fell as risk factors were recognised and and protective factors implemented. Significant factors affecting the risk of optic depositions included certain combinations of topical medication; the incidence of these deposits fell during 2002 after risk factors had been identified. These factors acted together to influence device retention rates and the probability of 1-year survival, which varied between 100%, prior to an interruption in medroxyprogesterone prescription, to 70% at the end of 2001, with an improving trend in the probability of 1-year survival through 2002, to 80%. Refractive outcomes for the device were initially highly myopic, with a trend to more predictable outcomes after introduction of a choice of aphakic and phakic models. Conclusions: The small series and follow-up to date have represented an intense learning curve for this new device. Detailed outcome and trend analysis have enabled early recognition of risk and protective factors. Further data collection and analysis as the series size and maximum follow-up increase should enable further improvements in patient management and outcomes to be achieved.
Keywords: keratoprostheses • clinical (human) or epidemiologic studies: out • clinical (human) or epidemiologic studies: ris