Risk factors of regression and undercorrection in photorefractive keratectomy: a case-control study

AIM: To determine risk factors of regression and undercorrection following photorefractive keratectomy (PRK) in myopia or myopic astigmatism. METHODS: A case -control study was designed in which eyes with an indication for re-treatment (AT) were defined as cases; primary criteria for RT indication, as assessed at least 9mo postoperatively, included an uncorrected distance visual acuity (UDVA) of 20/30 or worse and a stable refraction for more than 3mo. Additional considerations included optical quality symptoms and significant higher order aberrations (HOAs). Controls were chosen from the same cohort of operated eyes which had complete post-operative follow up data beyond 9mo and did not need RT. The cohort included patients who had undergone PRK by the Tissue-Saving (TS) ablation profile of Technolas 217z100 excimer laser (Bausch & Lomb, Rochester, NY, USA). Mitomycin C had been used in all of the primary procedures. RESULTS: We had 70 case eyes and 158 control eyes, and they were comparable in terms of age, sex and follow -up time (P values: 0.58, 1.00 and 0.89, respectively). Pre-operative spherical equivalent of more than -5.00 diopter (D), intended optical zone (OZ) diameter of less than 6.00 mm and ocular fixation instability during laser ablation were associated with AT indications (all P values <0.001). These factors maintained their significance in the multiple logistic regression model with odd ratios of 6.12, 6.71 and 7.89, respectively. CONCLUSION: Higher refractive correction (>-5.00 D), smaller OZ (<6.00 mm) and unstable fixation during laser ablation of PRK for myopia and myopic astigmatism were found to be strong predictors of undercorrection and regression.

Refractive surgery: the most cost-saving technique in refractive errors correction

AIM： To compare the lifetime and annual economic burden of spectacles, contact lenses, and refractive surgery in correction of refractive errors.METHODS： This is a cross-sectional study with convenience sampling which 120 patients were interviewed in a tertiary referral hospital in the Iranian health care system. The bottom-up based cost of illness approach was estimated using a face-to-face interview to assess the direct and indirect cost of different refractive errors correction of any correction technologies. RESULTS： Correction with spectacle imposes a total direct cost of US dollar （US$） 342.5 （±8.41） per year and US$9373.5 （±230.1） per lifetime to each patient. These figures for the contact lenses were obtained US$198.3 （±0.12） and US$5203.1 （±256.3） and for refractive surgery were obtained US$19.1 （±1.2） and US$568.1 （±64.6）, respectively. Overall, based on age-adjusted prevalence rates, astigmatism had the highest share of refractive errors economic burden with a lifetime direct cost of slightly less than US$5.49 billion, while hyperopia and myopia imposed less than US$5.24 and 4.2 billion on patients, respectively. The annually imposed cost on each individual Iranian patient with refractive errors is US$308.5. CONCLUSION： Based on 18mo post refractive surgery course observation, which is generalized to whole life, refractive surgery significantly imposed much less cost compared with spectacles and contact lenses. Refractive errors among Iranians result in considerable economic burden. Using the refractive surgery instead of other two correction methods has the ability to reduce this economic loss in the future.

Cost-effectiveness analysis of tele-retinopathy of prematurity screening in Iran

AIM:To conduct a cost-utility analysis of the teleretinopathy of prematurity(ROP)screening program against no screening.METHODS:A decision tree model was developed to identify and treat the infants with threshold ROP through the tele-screening system compared with no screening program from the societal perspective.We used the quality adjusted life years(QALY)index to measure the scenarios’effectiveness,which was discounted for the future years by 0.058.One hundred twenty-six randomly selected newborns with ROP required treatment were investigated to extract the treatment information.We considered the direct medical and non-medical costs in cost calculations analysed by the bottom-up approach.The figures of the model’s inputs were calculated using the Monte Carlo simulation that generated 1000 random iteration of the data,and a one-way sensitivity analysis was performed on the model to cope with the potential uncertainties.RESULTS:The total and per capita needed the budget to establish a tele-ROP screening system were estimated at over 1.5 million and 35.13 USD,respectively.The total cost of identifying and treating an ROP case in tele-screening and no screening strategies were obtained as 108.72 and 63.52 USD,respectively,and their lifetime discounted QALY gained were calculated as 15.39 and 15.11,respectively.Therefore,incremental cost-effectiveness ratio(ICER)of tele-screening strategy against the competitive strategy was achieved as 161.43 USD.CONCLUSION:Tele-ROP screening program is one of the most cost-effective interventions in the Iranian health system and has a high priority to receive a budget for implementation.