A Comparative Study of Measurement Repeatability for Two Aberrometers
试验速览
- 阶段
- 不适用
- 入组人数
- 60
- 主要终点
- 2nd to 4th order aberrations (5mm pupil).
研究概览
简要总结
Wavefront scans are a common form of diagnostic test applied in preparing patients for laser eye surgery. An optical map of the eye is created by wavefront scanning, and information from these maps is used to program lasers used to correct focusing errors in the eye. Here the investigators are comparing how repeatable measurements are with a new wavefront scanner and one that is already in widespread use.
详细描述
Aberrometers are used to measure each element of defocus (aberration) in an optical system. In LASIK, information derived from aberrometry (scans performed using aberrometers) is used to program the pattern of laser pulses delivered by an excimer laser in therapeutic reshaping of the cornea to correct defocus. To do this accurately, aberrometry findings need to be repeatable and correspond closely to manifest refraction. Here the investigators compare repeatability of measurements for a new aberrometer (Peramis) versus the aberrometer most widely used in contemporary wavefront guided laser vision correction (iDesign).
The test aberrometer will be:
Peramis (Schwind Eye-tech Solutions, Kleinostheim, Germany).
Control aberrometer will be:
iDesign (AMO, Santa Clara, CA)
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Diagnostic
- 盲法
- Single (Investigator)
入排标准
- 年龄范围
- 21 Years 至 60 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Myopic LASIK candidates (manifest refraction spherical equivalent range 0 to -10 diopters with up to 6 diopters cylinder) or patients attending corneal service with stage II-III keratoconus or post-keratoplasty
排除标准
- •Visually significant co-pathology (CDVA<6/6) other than irregular astigmatism;
- •Patients unable to complete a sequence of 2 good scans (acquisition diameter >5mm) in one eye within 4 attempts
研究组 & 干预措施
Myopia (Peramis)
Peramis aberrometry: 30 consecutive LASIK candidates with myopia and regular astigmatism who agree to participate in the study will have up to 4 aberrometry scans acquired consecutively using the Peramis (test) aberrometer.
干预措施: Peramis aberrometry (Device)
Myopia (iDesign)
iDesign aberrometry: The same 30 consecutive LASIK candidates scanned in the Myopia (Peramis) arm will also have up to 4 aberrometry scans acquired consecutively using the iDesign aberrometer (control) aberrometer. The order of scans (Peramis and iDesign) will be randomised.
干预措施: iDesign aberrometry (Device)
Irregular astigmatism (Peramis)
Peramis aberrometry: 30 consecutive cases with stage II-III keratoconus or post corneal transplantation cases with irregular astigmatism will have up to 4 aberrometry scans acquired consecutively using the Peramis (test) aberrometer
干预措施: Peramis aberrometry (Device)
Irregular astigmatism (iDesign)
iDesign aberrometry: 30 consecutive cases with stage II-III keratoconus or post corneal transplantation cases with irregular astigmatism will also have up to 4 aberrometry scans acquired consecutively using the iDesign aberrometer (control) aberrometer. The order of scans (Peramis and iDesign) will be randomised.
干预措施: iDesign aberrometry (Device)
结局指标
主要结局
2nd to 4th order aberrations (5mm pupil).
时间窗: <10 seconds
M, J0, J45, Coma, Trefoil, Spherical Aberration. Different types of defocus or aberration can be defined and measured by wavefront scanning. Aberrations are classified and quantified by a mathematical treatment called Zernike analysis in which harmonic elements of the waveform of the light detected by the wavefront sensor (aberrometer) are quantified in sequence, starting with simple (lower order) waveforms such as sphere and cylinder (M, J0, J45) corrected in a normal spectacle prescription, and progressing through more complex (higher order) waveforms including, coma, trefoil and spherical aberration which may influence quality of vision. The amount of each aberration varies as a function of pupil size. So pupil size is standardised at 5mm diameter for quantification.
次要结局
- % of patients with qualifying scan sequence(<5 minutes)
研究者
Bruce Allan
Consultant Ophthalmic Surgeon
Moorfields Eye Hospital NHS Foundation Trust