Orbscan iiz

In this prospective, randomized clinical trial, a total of 300 eyes of 150 patients were included. The sample size was calculated based on a type I error of 0.01 and with an assumed power of 95%. Candidates for photorefractive keratectomy (PRK) were randomized into 3 groups using computer-generated random numbers (each consisted of 100 eyes of 50 patients) and matched according to age and sex. All surgeries were performed by one surgeon, and to prevent bias, drops were given by somebody else. The study adhered to the tenets of the Declaration of Helsinki, and its protocol was approved by the Ethics Committee of Mashhad University of Medical Sciences.
Inclusion criteria were candidates of PRK with spherical equivalent between −1 and −4 diopters (D) and central corneal thickness (CCT) of 520–560 μm based on Orbscan (OrbscanIIz, Bausch and Lomb) who signed the written consent to enter the study.
Exclusion criteria were any history of steroid induced ocular hypertension, POAG, first degree relatives of POAG, DM, glaucoma suspect, connective tissue disease, history of corticosteroid usage in the past 2 months, high baseline IOP (≥22 mmHg), any ocular condition contraindicating corticosteroid usage, and any systemic disease or medication capable of affecting IOP (i.e. hypothyroidism).

Preoperative assessment included manifest and cycloplegic subjective refraction and autorefraction. Logarithm of the minimum angle of resolution (logMAR) visual acuity was assessed. Slit lamp biomicroscopy, mydriatic fundoscopy, and assessment of intraocular pressure and mesopic pupil diameter were performed. Preoperative slit-scan corneal topography (Orbscan IIz; Bausch & Lomb, Rochester, NY, USA), corneal wavefront analysis (Keratron Scout Topographer; Optikon SpA, Rome, Italy), and total ocular wavefront measurement (Hartmann-Shack Aberrometer/ORK-Wavefront Analyzer; SCHWIND eye-tech-solutions) were also carried out.

This study was a retrospective audit of consecutive eyes that underwent SMILE between March, 2012 and July, 2014, at a single tertiary referral center (Singapore National Eye Center [SNEC]). The study followed the principles of the Declaration of Helsinki, with the local institutional review board providing ethics approval.
Eyes were included if they had stable refraction for at least 6 months, no soft contact lens wear for 1 week before or rigid contact lens wear for 2 weeks before surgery, and no other ocular disease or previous ocular surgery. Patients were excluded if they had keratoconus or suspected keratoconus, active ocular or systemic disease likely to affect corneal wound healing (eg, autoimmune conditions), severe dry eyes, or a calculated postoperative corneal residual bed thickness of less than 250 μm. Patients on immunosuppression therapy were also excluded.
All eyes had a standard preoperative evaluation that included slitlamp and dilated fundus examinations, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, and corneal topography (OrbscanIIz, Bausch & Lomb). Trained refractive optometrists and technicians performed all measurements and refraction to ensure accuracy and reproducibility.

Preoperative assessment included manifest and cycloplegic subjective refraction and Logarithm of the minimum angle of resolution (logMAR) visual acuity. Slit lamp biomicroscopy, measurement of intraocular pressure and dilated fundoscopy were performed. Preoperative scanning took place using corneal topography with an Orbscan IIz (Bausch & Lomb, Rochester, NY, USA), along with corneal wavefront analysis using a Keratron Scout Topographer (Optikon SpA, Rome, Italy) and total ocular wavefront measurement using a Hartmann–Shack aberrometer (ORK-Wavefront-Analyzer; Schwind, Kleinostheim, Germany). Finally, pachymetric measurements of the cornea, and the epithelium in particular, were performed using the Optovue OCT (Optovue, Fremont, CA, USA).