Measurement Repeatability in Contemporary Aberrometry

A Comparative Study of Measurement Repeatability for Two Aberrometers

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.

Study Overview

• Status: Unknown
• Conditions: Refractive Errors
• Intervention / Treatment: Device: Peramis aberrometry; Device: iDesign aberrometry

Detailed Description

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)

• Study Type: Interventional
• Enrollment (Anticipated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Angelique Thomas; Phone Number: 02075662156; Email: angelique.thomas@moorfields.nhs.uk
• Study Contact Backup: Name: Barbara Stacey; Phone Number: 02075662320; Email: barbara.stacey@moorfields.nhs.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years to 60 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• 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

Exclusion Criteria:

• 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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 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.	Device: Peramis aberrometry; A non-invasive photographic scan sequence acquired in under 10 seconds; Other Names: Wavefront scanning
Active Comparator: 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.	Device: iDesign aberrometry; A non-invasive photographic scan sequence acquired in under 10 seconds; Other Names: Wavefront scanning
Experimental: 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	Device: Peramis aberrometry; A non-invasive photographic scan sequence acquired in under 10 seconds; Other Names: Wavefront scanning
Active Comparator: 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.	Device: iDesign aberrometry; A non-invasive photographic scan sequence acquired in under 10 seconds; Other Names: Wavefront scanning

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
2nd to 4th order aberrations (5mm pupil).	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.	<10 seconds

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
% of patients with qualifying scan sequence	% of patients in whom two 5mm diameter aberrometry scans can be acquired within 4 attempts	<5 minutes

Collaborators and Investigators

• Sponsor: Moorfields Eye Hospital NHS Foundation Trust
• Investigators: Principal Investigator: Bruce Allan, MD FRCOphth, Moorfields Eye Hospital NHS Foundation Trust

Publications and helpful links

General Publications

• Visser N, Berendschot TT, Verbakel F, Tan AN, de Brabander J, Nuijts RM. Evaluation of the comparability and repeatability of four wavefront aberrometers. Invest Ophthalmol Vis Sci. 2011 Mar 10;52(3):1302-11. doi: 10.1167/iovs.10-5841.
• LeDue J, Jolissaint L, Veran JP, Bradley C. Calibration and testing with real turbulence of a pyramid sensor employing static modulation. Opt Express. 2009 Apr 27;17(9):7186-95. doi: 10.1364/oe.17.007186.
• Cagigal MP, Valle PJ. Wavefront sensing using diffractive elements. Opt Lett. 2012 Sep 15;37(18):3813-5. doi: 10.1364/ol.37.003813.
• Jung JW, Chung BH, Han SH, Kim EK, Seo KY, Kim TI. Comparison of Measurements and Clinical Outcomes After Wavefront-Guided LASEK Between iDesign and WaveScan. J Refract Surg. 2015 Jun;31(6):398-405. doi: 10.3928/1081597X-20150521-06.

Study record dates

Study Major Dates

• Study Start: March 1, 2016
• Primary Completion (Anticipated): June 1, 2016
• Study Completion (Anticipated): September 1, 2016

Study Registration Dates

• First Submitted: February 7, 2016
• First Submitted That Met QC Criteria: February 19, 2016
• First Posted (Estimate): February 22, 2016

Study Record Updates

• Last Update Posted (Estimate): February 22, 2016
• Last Update Submitted That Met QC Criteria: February 19, 2016
• Last Verified: February 1, 2016

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors
• Other Study ID Numbers: ALLB1019

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Yes
• IPD Plan Description: The investigators plan to publish summary descriptive data and analyses. Anonymised individual data will be available to systematic reviewers on request.