Comparison Between Femtosecond Assisted LASIK and Small Incision Lenticule Extraction (SMILE) for Correction of Myopia and Myopic Astigmatism
试验速览
- 阶段
- 不适用
- 发起方
- 入组人数
- 60
- 试验地点
- 2
- 主要终点
- refractive predictability(manifest refraction spherical equivalent using autorefractometer)
研究概览
简要总结
Aim of the work is to compare the results of femtosecond assisted LASIK and small incision lenticule extraction (SMILE) as regards safety, efficacy and predictability. As a secondary outcomes , the investigators will compare the results of both techniques on corneal biomechanics, dry eye measures, corneal asphericity and higher order aberration.
详细描述
Rationale and Background
LASIK (laser in situ keratomileusis) is a surgical procedure designed to correct refractive errors. LASIK involves creating a corneal flap using a microkeratome followed by reshaping the cornea using an excimer laser to remove tissue from the underlying stromal bed and then replacing the corneal flap.
LASIK evolved from a variety of techniques in refractive surgery. Keratomileusis, with both freeze and non-freeze techniques was used in the USA in the 1970s.This procedure was followed by automated lamellar keratoplasty (ALK), in which a microkeratome was used to create either a free cap or a hinged corneal flap. Tissue from the corneal bed was removed to alter the refractive error and the flap was replaced. Keratomileusis and ALK were relatively imprecise mechanical techniques. After the ophthalmic excimer laser has been developed, it has been used to reshape the cornea in a technique called photorefractive keratectomy (PRK). LASIK combines the technique of creating a hinged corneal flap from ALK with excimer laser ablation from PRK. Potential advantages of LASIK over PRK include earlier postoperative stabilization and faster improvement of visual acuity, less postoperative patient discomfort, shorter duration of postoperative medication use and an easier enhancement procedure.
However LASIK -like any other surgical procedures- is not without complications. Complications of LASIK include dry eye, glare and night vision complaints and the most serious flap complications which include button hole, free cap, incomplete flap, infection and inflammation.
Femtosecond lasers have been widely used in LASIK to fashion a corneal flap instead of mechanical microkeratome, which is followed by corneal ablation using excimer laser. The advantages of femotosecond or 'bladeless' LASIK over microkeratome LASIK flaps are more precise flap thickness, reduced postoperative dry eye symptoms, reduced flap dislocation and reduced incidence of buttonholes or free caps.
研究设计
- 研究类型
- Interventional
- 分配方式
- Non Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Age is 18 years or older.
- •Best corrected visual acuity of 6/
- •Manifest refraction spherical equivalent (MRSE) not more than 9diopters (D).
- •Refractive cylinder not more than 3 diopters (D).
- •No topographic evidence of forme frust keratoconus (FFKC).
- •No progressive change of sphere or cylinder more than 0.5 diopter per year.
排除标准
- •Previous history of ocular trauma or ocular surgery.
- •Concomitant active or previous ocular disease such as uveitis and glaucoma.
- •Systemic diseases affecting wound healing such as diabetes mellitus, collagen vascular diseases
结局指标
主要结局
refractive predictability(manifest refraction spherical equivalent using autorefractometer)
时间窗: change from baseline at 3 months postoperative.
• Refractive predictability, which is defined as the proportion number of eyes achieving a postoperative spherical equivalent (SE) within ±0.50 D of the intended target.
efficacy(Unaided distance visual acuity using snellen chart)
时间窗: change from baseline at 3 months postoperative.
Efficacy: defined as the proportion number of eyes achieving an unaided visual acuity (UDVA) of 20/20 or better postoperatively (efficacy= postoperative UCVA/preoperative BCVA %).
safety( Corrected distance visual acuity using snellen chart)
时间窗: change from baseline at 3 months postoperative.
Safety: defined as the proportion number of eyes that lost or gained one or more lines of postoperative best corrected visual acuity (BCVA) relative to the preoperative BCVA (Safety= Postoperative BCVA/preoperative BCVA %)
次要结局
- corneal hysteresis(change from baseline at 3 months postoperative.)
- schirmer test(change from baseline at 3 months postoperative.)
- corneal higher order aberrations.( total RMS)(change from baseline at 3 months postoperative.)
- corneal resistance factor(change from baseline at 3 months postoperative.)
- tear break up time test.(change from baseline at 3 months postoperative.)
研究者
Esraa Mohamed Adel Mohamed El-mayah
Assistant lecturer
Kasr El Aini Hospital