Measurement Repeatability in Contemporary Aberrometry

Refractive Errors Clinical Trial

Official title:

A Comparative Study of Measurement Repeatability for Two Aberrometers

Clinical Trial Details — Status: Not yet recruiting

Administrative data

• NCT number: NCT02687022
• Other study ID #: ALLB1019
• Status: Not yet recruiting
• Phase: N/A
• First received: February 7, 2016
• Last updated: February 19, 2016
• Start date: March 2016
• Est. completion date: September 2016

Study information

• Verified date: February 2016
• Source: Moorfields Eye Hospital NHS Foundation Trust
• Contact: Angelique Thomas
• Phone: 02075662156
• Email: angelique.thomas[@]moorfields.nhs.uk
• Is FDA regulated: No
• Health authority: United Kingdom: Research Ethics Committee
• Study type: Interventional

Clinical Trial Summary

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.

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)

Recruitment information / eligibility

• Status: Not yet recruiting
• Enrollment: 60
• Est. completion date: September 2016
• Est. primary completion date: June 2016
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 21 Years to 60 Years

Eligibility

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 Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Investigator), Primary Purpose: Diagnostic

Related Conditions & MeSH terms

• Refractive Errors

Intervention

Device:
• Peramis aberrometry
A non-invasive photographic scan sequence acquired in under 10 seconds
• iDesign aberrometry
A non-invasive photographic scan sequence acquired in under 10 seconds

Locations

Country	Name	City	State
n/a

Sponsors (1)

Lead Sponsor	Collaborator
Moorfields Eye Hospital NHS Foundation Trust

References & Publications (4)

Cagigal MP, Valle PJ. Wavefront sensing using diffractive elements. Opt Lett. 2012 Sep 15;37(18):3813-5. — View Citation

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. — View Citation

LeDue J, Jolissaint L, Véran 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. — View Citation

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. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	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	No
Secondary	% of patients with qualifying scan sequence	% of patients in whom two 5mm diameter aberrometry scans can be acquired within 4 attempts	<5 minutes	No