Overnight Orthokeratology Is Comparable With Atropine in Controlling Myopia
This is a retrospective cohort study for a three years period, the patients using atropine or OK lens were grouped according to the selection of the patients themselves; no special recommendations were done in our department. The benefits and possible defects of the two methods were all informed to the patients and their families. Including photophobia, poor near vision and the risk of increasing intraocular pressure (IOP) might confront when using atropine; the risks of unstable vision in the daytime, glare at night and risks of keratitis in OK lens user. At the time of treatment, the patients and their families understood the different methods for treating myopia and selected the method themselves. Patients with complete clinical data during the study period (3 years, from March 2009 to March 2012) and undergone full and regular examinations were included in this study. All participants had a visual acuity with distance correction of 0.1 logMAR (20/25) or better. Landolt C ETDRS Distance Chart was used. The UCVA (uncorrected visual acuity) and BCVA (best corrected visual acuity) were all measured between 2 and 4 pm for each patient. We used alpha of 0.05, power of 80%, and the sample size estimated was approximately 105 subjects for each group, the patients with former ID number were included. We selected the first 210 patients (105 atropine and 105 OK lens) met the inclusion criteria and who visited our department had smaller ID number in our hospital; a total of 105 patients who used OK lens and 105 patients who used 0.125% atropine (Wu-Fu pharmaceutical Cc., Inc., YiLan, Taiwan) every night before sleep. Previous study of Wu et al. had proved that low concentration atropine is effective in controlling the progression of myopia, 0.125% atropine was selected in the control group because that 0.125% atropine is the lowest concentration of atropine available and marketed in our country now. Their ages ranged from 7 to 17 years and myopia ranged from 1.5 to 7.5 D. Patients received 0.125% atropine and did not discontinue the drugs for more then 10 days during the study period (3 years). The study was approved by the ethics committee of China Medical University Hospital (Taichung, Taiwan) and was performed in accordance with the tenets of the Declaration of Helsinki for research involving human subjects. Informed consent was obtained from all participants. Comprehensive ophthalmic examinations were performed before treatment and at every visit. None of the participants had ocular insult or disease such as retinopathy, prematurity, neonatal problems, a history of genetic disease, and connective tissue disorders associated with myopia such as Strickler or Marfan syndromes. Clinical examinations included visual acuity, refraction error, slit lamp examination, ocular movements, intraocular pressure, and fundoscopy. Patients with organic eye disease, a history or evidence of intraocular surgery, and history of cataract were excluded from this study (Table 1). Non-cycloplegic subjective vision and cycloplegic objective refraction recorded at the visits before commencement of 0.125% atropine or OK lens treatment (baseline) and 1, 2, and 3 years after were compared. Myopic diopter and axial length were also checked every year after discontinuing use of OK lenses for 3 weeks in the summer vocation between the semesters. The refractive error (in diopters [D]) of each individual was measured after administering one drop of cycloplegic drug (1% mydriacyl; Alcon, Berlin, Germany). The data of the patients were detected each eye and the averages of the two eyes were used for analyzing; the differences of myopia degree between the two eyes over then 2 D and astigmatism over then 1.5 D were also excluded from this study. Individuals with myopia from 1.5 to 7.5 D (average, 4.25 ± 1.5 D) and astigmatism from 0 to 2.75 D (average, 0.75 ± 0.75 D) (negative cylinder was used in this study) were included in this study; cases of extreme high myopia (over 7.5 D) and astigmatism (over 2.75 D) were excluded. Auto-refraction (Autorefractor/auto-keratometer [ARK 700A; Nikon, Tokyo, Japan]) was conducted for both eyes by experienced optometrists who were trained and certified in the study protocols. Refractive data, sphere (s), negative cylinder (c), and axis measurements were analyzed.