ABSTRACT
BACKGROUND AND PURPOSE: Wavefront-guided ablations are based on wavefront sensing in a pupil dilated under mesopic conditions, or in patients with insufficient natural pupil dilation, after the application of mydriatic eye drops. The aim of this study was to investigate a potential influence of mydriatic eye drops on wavefront-sensing in terms of the predicted phoropter refraction (PPR). METHOD: In this prospective study 70 myopic eyes were measured in miosis and pharmacologically induced mydriasis with the Zywave aberrometer and automated refraction (Canon R-F10). 52 eyes were dilated with eye drops containing tropicamide 0.5 % and phenylephrine 2.5 %, in the remaining 18 eyes tropicamide 0.5 % was used. The PPR for a pupil diameter of 3.5 mm in miosis and in mydriasis, respectively, were compared and correlated to the corresponding values of the automated refraction. RESULTS: PPR values obtained in mydriasis were less myopic than in miosis. The sphere of PPR differed by an average of + 0.19 +/- 0.3 diopters (range: -1.07 to + 0.37 diopters) when using tropicamide 0.5 % and phenylephrine 2.5 %. With tropicamide 0.5 % eye drops the difference was + 0.25 +/- 0.4 diopters (range: -1.12 diopters to + 0.27 diopters). Cylinder values were not affected. Automated refraction yielded a smaller difference of + 0.16 +/- 0.33 diopters (tropicamide 0.5 % and phenylephrine 2.5 %) and + 0.1 +/- 0.19 diopters (tropicamide 0.5 %). Cylinder values changed significantly. CONCLUSION: The cycloplegic effect of mydriatic eye drops should be taken into account when interpreting aberration measurements and planning a wavefront-guided laser ablation.
Subject(s)
Aberrometry , Corneal Wavefront Aberration/diagnosis , Corneal Wavefront Aberration/surgery , Lasers, Excimer , Mydriatics/pharmacology , Myopia/surgery , Phenylephrine/pharmacology , Photorefractive Keratectomy , Refraction, Ocular , Signal Processing, Computer-Assisted , Tropicamide/pharmacology , Adult , Drug Therapy, Combination , Female , Humans , Male , Middle Aged , Myopia/diagnosis , Predictive Value of Tests , Prospective Studies , Sensitivity and Specificity , Young AdultABSTRACT
BACKGROUND: The aim of this study was to evaluate the clinical performance of the new aspheric ablation mode (Zyoptix Aspheric) in laser in situ keratomileusis (LASIK) using the Bausch & Lomb 217 Zyoptix 100 laser. This algorithm incorporates the asphericity of the cornea (Q-value), the corneal curvature (K-values) and the manifest refractive error to create an ablation pattern. PATIENTS AND METHODS: Clinical outcomes of three ablation patterns were compared: Group TS: 20 eyes treated with Zyoptix tissue-saving (refraction and keratometry based); Group AS: 54 eyes treated with Zyoptix Aspheric; Group PT: 20 eyes treated with Zyoptix personalised treatment (wavefront aberration-guided). In addition to our conventional exclusion criteria for LASIK, eyes with an astigmatic error of more than -1.75 diopter (D) and above-average higher-order aberrations (HOA RMS > 0.35 microm, excluding spherical aberrations) were excluded. RESULTS: After an initial nomogram adjustment of -0.25 D in the AS group, good refractive predictability was observed at the 3-month visit (mean spherical error 0.02 +/- 0.50 D, mean cylinder -0.35 +/- 0.30 D). Natural spherical aberrations could be maintained. Uncorrected contrast sensitivity with and without glare remained at spectacle-corrected levels before AS LASIK. The uncorrected low contrast visual acuity after AS LASIK was as good as the spectacle-corrected low contrast visual acuity before. The asphericity of the cornea was best preserved with AS. The efficacy index was 0.94 in both AS and PT, 0.86 in TS. CONCLUSIONS: AS without cyclorotational eye tracking has a clinical performance equivalent to PT with cyclorotational eye tracking and better than TS in eyes with low astigmatism and below average HOA.
Subject(s)
Keratomileusis, Laser In Situ/instrumentation , Lasers, Excimer/therapeutic use , Myopia/diagnosis , Myopia/surgery , Surgery, Computer-Assisted/instrumentation , Adult , Equipment Design , Equipment Failure Analysis , Female , Humans , Keratomileusis, Laser In Situ/methods , Male , Middle Aged , Retrospective Studies , Surgery, Computer-Assisted/methods , Treatment Outcome , Young AdultABSTRACT
The concentrations of the heavy metals lead, cadmium and mercury were measured in surface water samples of an industrialized city and its surroundings. All but one value of Cd (particular) were less than 0.5 microgram l-1, 30% of the lead (particular) values were less than 0.5 microgram l-1, 70% 0.5 ... 10 micrograms l-1, 86% of the total mercury less than 0.1 and 14% 0.1 ... 0.5 microgram l-1. By applying the differential-diagnostic assessment method it could be found that the highest values were found in the vicinity of a metal-using factory. On a sampling point near such an enterprise the part of particularly bound lead was very low, that means a recent input, whereas on another sampling point with a high total lead level 95% were particularly bound which refers to a continuous input.
