Measurement Repeatability in Contemporary Aberrometry

Moorfields Eye Hospital NHS Foundation Trust

Status: Unknown

Conditions: Refractive Errors

Treatments: Device: iDesign aberrometry; Device: Peramis aberrometry

Study type: Interventional

Funder types: Other

Identifiers

NCT02687022

ALLB1019

Details and patient eligibility

About

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.

Full 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)

Enrollment: 60 estimated patients

Sex: All

Ages: 21 to 60 years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Diagnostic

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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60 participants in 4 patient groups

Myopia (Peramis)

Experimental group

Description:

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.

Treatment:

Device: Peramis aberrometry

Myopia (iDesign)

Active Comparator group

Description:

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.

Treatment:

Device: iDesign aberrometry

Irregular astigmatism (Peramis)

Experimental group

Description:

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

Treatment:

Device: Peramis aberrometry

Irregular astigmatism (iDesign)

Active Comparator group

Description:

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.

Treatment:

Device: iDesign aberrometry