Retrospective analysis of actual LASIK flap diameter compared with microkeratome ring size performed by different surgeons.

PURPOSE: To evaluate the difference in the diameter between microkeratome ring and actual laser in situ keratomileusis (LASIK) flap size by 4 different surgeons using 3 different microkeratomes in comparison to preoperative keratometry. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: A retrospective analysis of 6667 consecutive LASIK surgeries performed at the Gimbel Eye Centre between 1998 and 2002 was conducted. The study compared the difference in the actual LASIK flap diameter and microkeratome ring size for 3 Hansatome microkeratomes indicated by serial numbers 2230, 3048, and 3084 in comparison to the preoperative keratometry. The surgeries were performed by 4 surgeons from the Centre. RESULTS: A statistically significant correlation was found between the actual flap size and the microkeratome ring size. The deviation increased with corneal steepness (#2230: r = 0.45, P<.001; #3048: r = 0.28, P<.001; #3084: r = 0.23, P<.001). The mean difference between actual flap size and the microkeratome ring size was 0.647 mm, 0.808 mm, and 0.916 mm for Hansatome microkeratome #2230, #3048, and #3084, respectively. The actual flap was larger than the microkeratome ring size in 92.8%, 93.8%, and 97.4% of eyes, respectively. The mean difference between microkeratome ring size and measured LASIK flap size was consistently significantly different (P<.0001) per surgeon for all microkeratomes. CONCLUSIONS: Estimation of the flap size is an important issue while selecting ring size and planning the treatment zone. In this study, the actual flap size was larger than the ring size for all surgeons and all 3 Hansatome microkeratomes. Higher preoperative keratometry values achieved larger flaps than those with lower keratometry values.

Wavefront-guided multipoint (segmental) custom ablation enhancement using the Nidek NAVEX platform.

PURPOSE: To present our clinical experience regarding enhancement (retreatment) of previously performed non-wavefront-guided refractive surgery by wavefront-guided multipoint (segmental) custom ablation utilizing the Nidek NAVEX platform. METHODS: Retrospective clinical analysis was conducted of 20 eyes (19 patients) with mixed myopic or hyperopic astigmatism who had undergone primary laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) and reported postoperative reductions in quality of vision. These vision disturbances correlated with clinically significant elevations in the root mean square of higher order aberrations (RMS of HOA) values. Before wavefront-guided multipoint (segmental) custom ablation enhancement with the NAVEX platform, all patients underwent testing with the Nidek Optical Path Difference Scan (OPD-Scan) and analysis with Final Fit Software. RESULTS: Twenty eyes showed improvement or resolution of visual symptoms following wavefront-guided multipoint (segmental) custom ablation enhancement. The postoperative root mean square of higher order aberration values were variable and not always related to improvement in visual function. No patient lost two or more lines of best spectacle-corrected visual acuity. CONCLUSION: Topography and wavefrontguided multipoint (segmental) custom ablation enhancements were safe and effective in improving visual symptoms following primary refractive surgery. In some eyes, improved visual function without correspondingly lower RMS of HOA values may be an effect of neutralizing some chromatic aberrations across the visible light spectrum, thereby improving the modulation transfer function.

Primary multipoint (segmental) custom ablation.

PURPOSE: We present our experience in resolving visual symptoms in refractive patients undergoing primary multipoint (segmental) custom ablation. METHODS: Twelve eyes with mixed myopic astigmatism underwent evaluation and primary treatment by multipoint (segmental) custom ablation for the correction of refractive errors and visual symptoms using the Nidek NAVEX platform. RESULTS: Twelve eyes showed resolution of visual symptoms following diagnosis and treatment with MCA using the NAVEX platform. No patient lost two or more lines of best spectacle-corrected visual acuity. The postoperative root mean square of higher order aberrations did not change in a predictable or reproducible fashion. CONCLUSION: Multipoint (segmental) custom ablation with the Nidek NAVEX system was safe and effective for correcting mixed myopic astigmatism and for resolving visual symptoms in selected refractive surgery candidates. Small changes in the root mean square of higher order aberration values were not always reflected in a patient's subjective assessment of vision quality.

AdvanTec Legacy System and the NeoSoniX handpiece.

AdvanTec Legacy System and the NeoSoniX handpiece (Alcon Surgical, Fort Worth, Texas) are improvements to the Legacy System that allow power modulation and customization of surgical technique in phacoemulsification surgery. AdvanTec technology allows power modulation in terms of occlusion power management, global linear flow, mode sequencing, and visco mode. The NeoSoniX handpiece combines sonic oscillations with linear ultrasound to reduce thermal energy during nucleus removal. The AdvanTec System allows lower power, less delivered energy, a lower risk of thermal burns, less chatter, and improved followability during phacoemulsification. These improvements translate into successful clinical outcomes.