ABSTRACT
Tears have antimicrobial, nourishing, mechanical, and optical properties and contain components such as growth factors, fibronectin and vitamins to support proliferation, migration and differentiation of corneal and conjunctival epithelial cells. Lack of these epitheliotrophic factors, as in dry eye, can result in severe ocular surface disorders such as persistent epithelial defects. Recently, the use of autologous serum in the form of eye drops has been reported as a new treatment for severe ocular surface disorders. Serum eye drops may be produced as an unpreserved blood preparation. They are by nature non-allergenic and their biomechanical and biochemical properties are similar to normal tears. In vitro cell culture experiments showed that corneal epithelial cell morphology and function are better maintained by serum than by pharmaceutical tear substitutes. Clinical cohort studies have reported its successful use for severe dry eyes and persistent epithelial defects. However, the protocols to prepare and use autologous serum eye drops varied considerably between the studies. In addition to different biochemical properties, protocol variations may also influence the epitheliotrophic effect of the product. Before establishing the definitive role of serum eye drops in the management of severe ocular surface diseases in a large randomized controlled trial, this has to be evaluated in more detail. Based upon the literature reviewed here, two preliminary standard operating procedures for the preparation of serum eye drops are proposed
ABSTRACT
To evaluate the 8-year results of excimer laser photorefractive keratectomy [PRK] for myopia in terms of safety, stability and late complications. Of 203 myopic patients who underwent PRK with single-step method using NIDEK EC-5000 excimer laser with 5-6 mm ablation zones at Basir Eye Center, Tehran-Iran from 1996 to 1998, 179 eyes of 98 patients who completed 8 years of follow up were included in this study. Results of follow up examinations at 1, 3, 6 and 12 months and 2 and 8 years after surgery were analyzed. Treated eyes were divided into three groups according to preoperative refractive error: low [ -10.00 D] myopes. Eight years after PRK, emmetropia [within +/- 1 D] was achieved in 69.1%, 30% and 46.15% of the low, medium and high myopia groups, respectively. Although a small myopic shift occurred up to 8 years after surgery, myopic regression stabilized in all groups within 24 months and was correlated significantly to preoperative spherical equivalent refraction. Corneal haze occurred in 5% especially in medium and high myopic groups but cleared within two years in 89% of cases. Only one eye lost two lines of best spectacle-corrected visual acuity due to corneal haze. According to this study, postoperative refraction remains stable two years after PRK and most cases of corneal haze clear within two years after surgery. Therefore, PRK seems to be a safe and stable surgical procedure in myopic patients