الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
As refractive surgery has become more accepted and popular, the ophthalmic investigative community has increased efforts to develop more sophisticated techniques for correcting visual errors. The hope is to not only address spherical and cylindrical refractive errors (low-order aberrations) but also to modify a spectrum of higher-order ocular aberrations to maximize the quality of vision. Optical aberrations vary after the formation of a LASIK flap whether it is microkeratome flap or femtoflap and it is a fundamental element in the development of flap induced aberrations.
Itrace device is a unique device which uses ray tracing technology to evaluate the total optical aberrations of the eye.
In our study, we aimed to evaluate quality of vision after conventional LASIK and femtoflap LASIK using ray tracing technology. Outcome measures included, visual acuity changes, root mean square and contrast sensitivity.
Our study included 40 eyes of 20 patients from both sexes had conventional LASIK and femtoflap LASIK.
Preoperative preparation started with full history taking, then every candidate was subjected to full ophthalmic examination, UCVA and BCVA measurement, pentacam, ray tracing, and contrast sensitivity.
Then, half of patients (10 patients-20 eyes) under went to conventional LASIK using wave light IQ excimer laser to do flap and ablation and the other half (10 patients-20 eyes) under went to femtoflap LASIK using femtosecond laser (VisuMax, Carl Zeiss Meditec, Inc., Dublin, CA) was used to create the flap and the hinge with a wave length of about 1,040 nm and 1 μm spot size, laser frequency is 500 kHz. Then they turned to wave light IQ excimer laser to do the ablation. Then, the flap is replaced and allowed to heal.
Postoperatively, antibiotics and steroids will be instilled in addition to artificial tears.
Postoperatively, UCVA and BCVA measurement, ray tracing, and contrast sensitivity.
Collected data were subjected to statistical analysis and the following results were obtained:-
1. No significant difference in Visual acuity that remained stable postoperatively with both treatments through 1week, 1 month, and 3 months with no change in manifest refractive error.
2. Significant differences in high-order aberrations do exist between methods of flap creation, but are small and likely to be clinically insignificant.
3. No statistical significant decrease in photopic contrast sensitivity at any spatial frequency after both LASIK groups. At 12 and 18 cpd spatial frequencies, contrast sensitivity values of the postoperative mechanical LASIK group were statistically significantly lower than those obtained in the preoperative mechanical LASIK group under mesopic conditions.