Customization of laser ablation profiles using Bowman’s layer topography
试验速览
- 阶段
- 4 期
- 状态
- 尚未招募
- 入组人数
- 80
- 试验地点
- 1
- 主要终点
- Visual acuity corrected and uncorrected, wavefront aberrations
研究概览
简要总结
For years, conventional refractive treatment hasbeen based on refractive error of the patient. Ablation of the tissue isplanned assuming topography of the anterior surface of the cornea, which isactually the air-epithelium interface. However, the treatment is actuallydelivered to the stroma. It is generally assumed that the topography of theBowman’s layer is the same as the topography of the anterior surface of thecornea. However, new evidence suggests that this may not be the case in normalcorneas [1]. In keratoconic corneas as well, topography of the anterior surfaceof the cornea can be different from the topography of the Bowman’s layer [2].Therefore, our hypothesis is that planning of ablation pattern can benefit fromthe topography of the Bowman’s layer. This can lead to potentially betterrefractive and aberration outcomes. To achieve this, we have developed novelimage processing methods, where optical coherence tomography scans of thecornea can be used to reconstruct the topography of the anterior surface aswell as the Bowman’s layer. Our method is fully non-invasive and can beperformed pre-operatively unlike past studies [1, 2]. Figure 1 shows an exampleof a normal eye with Pentacam topography (left), OCT topography of the anteriorsurface (middle) and OCT topography of the Bowman’s layer (right). Note thedistinct change in pattern of astigmatism from inferior to regular astigmatism.Thus surgical planning based on Bowman’ layer topography will be different fromthe topography of the anterior surface.
References:
1. Salah-MabedI, Saad A, Gatinel D. Topography of the corneal epithelium and Bowman layer inlow to moderately myopic eyes. J Cataract Refract Surg. 2016; 42(8): 1190-7.
2. TouboulD, Trichet E, Binder PS, Praud D, Seguy C, Colin J. Comparison of front-surfacecorneal topography and Bowman membrane specular topography in keratoconus. JCataract Refract Surg. 2012; 38(6): 1043-9.
3. JainAK, Malhotra C, Pasari A, Kumar P, Moshirfar M. Outcomes of topography-guidedversus wavefront-optimized laser in situ keratomileusis for myopia in virgineyes. J Cataract Refract Surg. 2016; 42(9): 1302-1311
研究设计
- 研究类型
- Interventional
- 分配方式
- Computer generated randomization
- 盲法
- Open Label
入排标准
- 年龄范围
- 18.00 Year(s) 至 50.00 Year(s)（—）
- 性别
- All
入选标准
- •Patients should be between 18 to 50 years of age.
- •Patient must have stable myopia for a minimum period of one year (a change of 0.25D or less) as documented by prior clinical records or current spectacle correction.
- •Patient must have a corrected distance visual acuity of 0.8 Decimal or better,
- •Patient must have a spherical equivalent refraction less than -10D
- •Patient must have refractive astigmatism less than -3D.
排除标准
- •Patient must not have a central corneal thickness less than 480 micrometer 2.Patient must not have a calculated residual s stromal bed thickness of less than 250 micrometer after the surgery
- •Patient must not have symptoms or signs of keratoconus, diabetes, collagen vascular disease, pregnancy, breastfeeding and any prior ocular surgery.
- •Patient must not have an inter-ocular difference of more than 1.00 diopter of spherical or 0.50 D of cylindrical refractive error.
- •Patient must not be on chronic systemic steroids or other medication that can affect wound healing.
- •Patient must not be allergic to primary or alternative medications.
- •Patient must not be using rigid contact lenses for the last three weeks or soft contact lenses for at least 1 week before the preoperative evaluation.
结局指标
主要结局
Visual acuity corrected and uncorrected, wavefront aberrations
时间窗: Pre-surgery, 1 week, 1 month, 3 month, 6 month
次要结局
- Corneal tomography and biomechanical response(Pre-surgery, 1 week, 1 month, 3 month, 6 month)