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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.
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)
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Myopia (Peramis) | Experimental | 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. |
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| Myopia (iDesign) | Active Comparator | 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. |
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| Irregular astigmatism (Peramis) | Experimental | 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 |
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| Irregular astigmatism (iDesign) | Active Comparator | 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. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Peramis aberrometry | Device | A non-invasive photographic scan sequence acquired in under 10 seconds |
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| 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 |
| 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 |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Angelique Thomas | Contact | 02075662156 | angelique.thomas@moorfields.nhs.uk | |
| Barbara Stacey | Contact | 02075662320 | barbara.stacey@moorfields.nhs.uk |
| Name | Affiliation | Role |
|---|---|---|
| Bruce Allan, MD FRCOphth | Moorfields Eye Hospital NHS Foundation Trust | Principal Investigator |
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| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 21051697 | Background | 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. | |
| 19399094 | Background | 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. |
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The investigators plan to publish summary descriptive data and analyses. Anonymised individual data will be available to systematic reviewers on request.
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| ID | Term |
|---|---|
| D012030 | Refractive Errors |
| ID | Term |
|---|---|
| D005128 | Eye Diseases |
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| iDesign aberrometry | Device | A non-invasive photographic scan sequence acquired in under 10 seconds |
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| 23041868 | Background | Cagigal MP, Valle PJ. Wavefront sensing using diffractive elements. Opt Lett. 2012 Sep 15;37(18):3813-5. doi: 10.1364/ol.37.003813. |
| 26046707 | Background | 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. |