Wavefront aberrations and subjective quality of vision after wavefront-guided LASIK: first results

PURPOSE: To investigate the clinical impact of the postoperative ocular wavefront error (WFE) on subjective quality of vision (SQV) after LASIK. METHOD: Forty-one myopic eyes of 21 patients underwent uneventful LASIK (median -4.63 D). Preoperatively and 1 month postoperatively, WFE measurements were performed and overall SQV was assessed for two lighting conditions (photopic and mesopic) with a questionnaire. Three different WFE representations were computed for a pupil diameter of 6 mm: (1) the visual quality metric VSOTF (visual Strehl ratio based on the optical transfer function), (2) RMS (root mean square) values of the Zernike orders 2-5, and (3) individual Zernike coefficient for orders 2-5. The impact of the postoperative WFE on SQV was calculated using linear regression analysis. RESULTS: For photopic conditions R(2) was 0.24 for model 1 (VSOTF), 0.31 for model 2 (RMS values), and 0.29 for model 3 (Zernike coefficients). Second-and fifth-order aberrations had significant influence on SQV. For mesopic conditions, results were similar. CONCLUSION: Subjective quality of vision after wavefront-guided LASIK could be explained partially by the ocular WFE.     

Application of wavefront analysis in clinical and scientific settings. From irregular astigmatism to aberrations of a higher order--Part I: Basic principles

In recent years, wavefront analysis has emerged from a pure laboratory application to an ophthalmological diagnostic method. This development was promoted mainly by the widespread use of wavefont-guided LASIK. However, aberrometry is still not a common diagnostic technique and the results of measurements are difficult to understand and to interpret for many ophthalmologists. The first part of this 2-part series summarizes the basics of wavefront errors, aberrometry and wavefront analysis to give a comprehensive overview for the interested ophthalmologist and clinical scientist. The second part will review such findings that are relevant for the ophthalmological community and highlight current scientific applications.     

Derzeitiger Stand der wellenfrontgeführten Hornhautchirurgie zur Korrektur von Refraktionsfehlern

The present review describes the current status of wavefront-guided corneal surgery and up-to-date results. Wavefront-guided LASIK procedures performed to date achieved uncorrected vision of 1.0 or better in a larger number of patients than with conventional LASIK surgery, but the “eagle eye” has remained the exception. In part of the patients reductions of higher order aberrations could be obtained, but in the majority of cases an increase was observed. This increase was however less than with conditional LASIK surgery. Correction of higher order aberrations has not yet been perfected since the predictability of corrections appears to be deserving of improvement on the one hand and aberrations are still induced by the technique on the other hand.     

Substitution of conventional cyclosporin with a new microemulsion formulation in renal transplant patients: results after 1 year

BACKGROUND: A new galenic form of cyciosporin A has been developed, basedon microemulsion technology. The bioavailability of the compoundis reiativeiy independent of food intake and bile flow. It wasthe purpose of this prospective clinical trial to study thesafety of the microemulsion form of cyclosporin A. METHODS: Three hundred and two renal transplant patients, stratifiedaccording to transplant age, were switched from the conventionalto the new micro-emulsion formulation of cyclosporin A. A 1:1conversion ratio was used. Measurements included CsA levels,S-creatinine, liver enzymes, uric acid, and blood pressure.Measurements were performed at baseline and on days 4, 8, 15,29 and months 3, 6 and 12 after conversion. Dose adjustmentswere performed to achieve trough levels of 80–120 ng/ml. RESULTS: Within the 12-month observation period the cyclosporin dosewas reduced by 14.7% (from 204±60 mg/day at baselineto 174±51 mg/day after conversion, P<0.001). Acutely,i.e. by day 8, a 1:1 dose conversion resulted in a modest increaseof mean drug trough levels (from 114 ng/ml at baseline to 120ng/ml, P<0.01). This increase was accompanied by an increasein serum creatinine concentration, a decrease in calculatedcreatinine clearance, and an increase in uric acid values (P0.05).Liver enzymes remained unchanged while systolic and mean arterialblood pressure decreased (P<0.05). After 1 month, drug troughlevels had decreased to baseline (112 ng/ml) and remained thereuntil month 6. They were significantly lower after 12 months(102±33 ng/ml, P<0.001). Creatinine clearance valuesincreased to above baseline at 6 and 12 months. Within the 1-yearperiod there occurred 24 (=8%) episodes of biopsy-proven rejectionand seven episodes of cyclosporin-attributed nephrotoxicity. CONCLUSIONS: The 1:1 conversion from conventional cyclosporin A to the microemulsionformulation is efficacious and safe, but an initial dose reductionof 10% is advised in patients with trough levels in the high-normalrange.