Rm 8900 auto refractometer

All patients underwent wavefront optimized laser refractive surgery, PRK in 50 eyes and LASIK in 106 eyes, for correction of simple, myopic, hyperopic or mixed astigmatism, applying WaveLight EX500 (Alcon Laboratories; Ft Worth, TX, USA). All surgeries were performed by a single surgeon, the author. A superior hinge was applied in LASIK cases using Moria Evolution 3 Microkeratome (Moria, Antony, France) with a programmed planned flap thickness of 110 μm and a diameter of 8 mm. In PRK, the corneal epithelium was removed in a diameter of 8 mm in a centripetal fashion using a blunt hockey blade. UCVA and manifest refraction were evaluated at 1 month post-operatively. Postoperative refraction was assessed by a TOPCON RM-8900 Auto Refractometer (Topcon Medical Systems, Tokyo, Japan).

All patients underwent manifest and cycloplegic refractions by a TOPCON RM-8900 Auto Refractometer (Topcon Medical Systems, Tokyo, Japan), measurements of the uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA).
All eyes were subjected to corneal topography assessment by Allegro Topolyzer-Vario (WaveLight, Erlangen, Germany) and Scheimpflug tomography examination by Allegro Oculyzer ІІ (WaveLight, Erlangen, Germany). The Oculyzer presents a Scheimpflug rotating camera, with a 360 degrees rotating light beam, scanning the cornea with a high density of points from the corneal centre. In contrast, the Topolyzer is a placido-disk-based system with a camera imaging reflections from the surface of the cornea. Since the Topolyzer camera is located at the centre of the topographer, a central scotoma is produced corresponding to the camera location, and hence a small area of central corneal data are extrapolated.10 (link)
Patients enrolled in the study had pre-operative pachymetry ≥460 microns (μm) for PRK and ≥500 μm for LASIK. PRK subjects were required to retain an average post-operative residual corneal bed ≥380 μm. LASIK subjects were required to retain an average post-operative residual corneal bed ≥300 μm.