الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In the last few decades, refractive surgery has developed rapidly and readily. the technological advances and the high precision of the refractive procedures led to putting the field on top of the list of the most performed procedures worldwide.
It has evolved from incisional surgeries to Laser ablation procedures and laser photodisruption techniques using the femtosecond laser technologies.
Nowadays different surgical techniques are available to suit every patient, all of which depend on modifying the corneal shape and asphericity. However, few drawbacks and complications may arise leading to dissatisfaction of the patients.
Of which, the functional optical zone was one of the factors that has been readily studied in order to tackle the undesired effects of the subsequent aberrations and the deterioration of the visual quality.
The aim of this work was to compare between the planned and the achieved optical zone diameters in Laser in Situ Keratomileusis (LASIK) and refractive Lenticule Extraction (ReLEX Smile) procedures.
This prospective non-randomized clinical study was conducted on 120 eyes of the 60 patients who were equally distributed into 2 groups:
group A: underwent Lasik procedure using Wavelight EX500 Excimer laser platform (Alcon, USA)
group B: underwent ReLEX Smile procedure using Zeiss Visumax platform (Zeiss, Germany)
The achieved optical zone diameter of each case was measured on the topographic maps of the Oculus pentacam system and then compared with planned/programmed optical zone diameter provided by the manufacturer.
The results showed that in the Lasik group, the achieved diameter was 1.84 ± 0.24 mm less than planned diameter which is a statistically significant result.
In the Smile group, the achieved diameter was 0.93 ± 0.14 mm less than the planned diameter which is also statistically significant.
We also showed that there is a significant reduction in the contrast sensitivity testing at 3 months postoperatively where the higher frequencies are more affected than the lower ones.
It was concluded that Both Smile and LASIK resulted in reduction of the effective optical zone during correction of myopia. However, Smile resulted in less reduction than LASIK.
It was also concluded that at 3 months postoperatively, there is a reduction in the contrast sensitivity in both groups when compared with the preoperative values.