purpose : to evaluate the accuracy of the two methods the clinical history method (chm), and the contact lens method (clm), in refractive corneal power determination and comparing the accuracy of srk ii, srk t and holladay ii (h ii) formulas for intraocular lens (iol) power calculation in patients who had laser in situ keratomileusis (lasik) surgery for myopia with or without astigmatism method...

PURPOSE To evaluate with the use of corneal topographic data the differences between total corneal power calculated using ray tracing (TCP) and the Gaussian formula (GEP) in normal eyes, eyes that previously underwent laser in situ keratomileusis/photorefractive keratectomy (LASIK/PRK), and theoretical models. METHODS TCP and GEP using mean instantaneous curvature were calculated over the cen...

BACKGROUND Efficacy and high availability of surgery techniques for refractive defect correction increase the number of patients who undergo to this type of surgery. Regardless of that, with increasing age, more and more patients must undergo cataract surgery. Accurate evaluation of corneal power is an extremely important element affecting the precision of intraocular lens (IOL) power calculati...

Purpose. To validate clinically a new method for estimating the corneal power (P c ) using a variable keratometric index (n kadj) in eyes with previous laser refractive surgery. Setting. University of Alicante and Medimar International Hospital (Oftalmar), Alicante, (Spain). Design. Retrospective case series. Methods. This retrospective study comprised 62 eyes of 62 patients that had undergone ...

NOVEMBER/DECEMBER 2012 CATARACT & REFRACTIVE SURGERY TODAY EUROPE 1 A ccuracy of biometric calculations and, more important, of refractive results depends on three main factors: preoperative biometric data including axial length, anterior chamber depth, lens thickness, and corneal curvature power variables; power calculation formulas; and quality and accuracy of the IOL. In the past 15 years, s...

Intraocular lens (IOL) power calculations are known to be difficult in eyes that have had corneal refractive surgery and several methods have been proposed to estimate IOL power. Among the methods not requiring preoperative data, the apahakic refraction technique has been successfully used to calculate IOL power in post-refractive cases and other conditions that cause unreliability in standard ...

PURPOSE To compare the corneal power measurements obtained using different topographic instruments after myopic photorefractive keratectomy (PRK). METHODS Patients with myopia who were candidates for corneal refractive surgery were sequentially included. Pre-PRK and six months post-PRK corneal powers were measured using Javal manual keratometer, Orbscan II, Galilei, Tomey TMS4, and EyeSys 200...

PURPOSE To investigate the association between ocular biometrics such as axial length (AL), anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD) and corneal power (CP) with different refractive errors. METHODS In a cross-sectional study on the 40 to 64-year-old population of Shahroud, random cluster sampling was performed. Ocular biometrics were measured using the A...

Maintenance of corneal hydration is dependent on the active transport properties of the corneal endothelium. We tested the hypothesis that lactic acid efflux, facilitated by buffering, is a component of the endothelial fluid pump. Rabbit corneas were perfused with bicarbonate-rich (BR) or bicarbonate-free (BF) Ringer of varying buffering power, while corneal thickness was measured. Perfusate wa...