Photorefractive Intrastromal Crosslinking (PiXL) for the Treatment of Progressive Keratoconus
Study Details
Study Description
Brief Summary
The purpose of this study is to evaluate the efficacy, safety and postoperative ocular discomfort by comparing individually customized Photorefractive intrastromal crosslinking (PiXL) for progressive Keratoconus. The study compares two different protocols, PiXL with corneal epithelium debridement (Epi-off) and PiXL without epithelium debridement in high oxygen environment (Epi-on), with the hypothesis that Epi-on gives less postoperative ocular discomfort.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
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N/A |
Detailed Description
The study is designed as a prospective, single-masked intraindividually comparing randomized controlled trial involving participants of both genders aged 18-35 years with Keratoconus planned for routine corneal crosslinking at the Department of Ophthalmology, Umeå University Hospital, Umeå, Sweden. The study includes 30 participants with bilateral Keratoconus, receiving Epi-off PiXL (n=30) in one eye and Epi-on PiXL in high oxygen environment (n=30) in the fellow eye. The participants are randomized utilizing a list of unique random numbers between 1 and 30; an even number will be treated with Epi-on in the right eye; an uneven number will receive Epi-on in the left eye; the fellow eye will be treated with Epi-off. All patients are informed about the procedures before consenting to participate in the study.
At baseline, before treatment, each eye is examined with slit-lamp microscopy, subjective refraction, determination of uncorrected (UCVA), low contrast visual acuity at 2.5 percentage contrast and 10 percentage contrast and best corrected (BSCVA) visual acuities using the LogMAR fast protocol and intraocular pressure (IOP) using Goldmann applanation tonometry. Under standardized, mesopic light conditions each eye is evaluated by keratometry readings and central corneal thickness, extracted from Schemipflug camera measurements, Pentacam HR® (Oculus, Inc. Lynnwood, WA).
Central corneal endothelial photographs are taken with the Topcon SP-IP specular microscope (Topcon Europe B.V., Capelle a/d Ijssel, the Netherlands) and total ocular wavefront is measured with iTrace (Tracey Technologies, Inc.).
Ocular discomfort is subjectively evaluated in each eye by a specific visual analogous rating scale at 4h, 8h, 12h, 24h and thereafter daily up to 1 week postoperatively.
All the above mentioned examinations are repeated at 1, 3, 6, 12 and 24 months after treatment. At 1 day and 1 week after treatment, solely UCVA, Auto refractor measurements, slit-lamp examination are evaluated.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Experimental: Epi-on PiXL Photorefractive intrastromal corneal crosslinking without epithelium debridement during humidified high oxygen flow. |
Procedure: Epi-on PiXL
Photorefractive intrastromal crosslinking (PiXL) After local anaesthetics, the keratoconus cornea is soaked in Riboflavin by repeated topical application during 10 minutes. For masking purposes, epithelial debridement is simulated by moving a scraping instrument in front of the cornea. A Riboflavin soaked sponge is used to lightly disrupt the epithelium tight junctions, without epithelium debridement. The cornea is illuminated with PiXL under 16:40 minutes during continuously delivery of humidified high oxygen via specific oxygen goggles. The UV-dosage is individually customized based upon Kmax; for < 45 Diopters (D) 7.2J/cm2 is used; for 45-50D 10J/cm2 is used; for > 50D 15 J/cm2 is used.
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| Active Comparator: Epi-off PiXL Photorefractive intrastromal corneal crosslinking with epithelium debridement. |
Procedure: Epi-Off PiXL
Photorefractive intrastromal crosslinking (PiXL) After local anaesthetics, the corneal epithelium is debrided and the keratoconus cornea is soaked in Riboflavin by repeated topical application during 10 minutes. The cornea is then illuminated with individually customized PiXL under 16:40 minutes. The UV-dosage is individually customized based upon Kmax; for < 45D 7.2J/cm2 will be used; for 45-50D 10J/cm2 will be used; for > 50D 15 J/cm2 will be used.
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Outcome Measures
Primary Outcome Measures
- Change from baseline in uncorrected visual acuity [1 month, 3 months, 6 months, 12 months and 24 months after treatment]
Change from baseline in distance uncorrected visual acuity, LogMAR units
- Change from baseline in keratometry readings [1 month, 3 months, 6 months, 12 months and 24 months after treatment]
Kmean (average), K1 (flat meridian), K2 (steep meridian) and Kmax (steepest radius of curvature) assessed with the Pentacam HR Scheimpflug camera, Diopters.
- Change from baseline in Ocular Discomfort Scores [4 hours, 8 hours, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days and 7 days after treatment]
Change from baseline in Ocular Discomfort Scores, Visual Analog Score (0 (no discomfort) - 10 (maximum discomfort))
Secondary Outcome Measures
- Change from baseline in refraction [1 month, 3 months, 6 months, 12 months and 24 months after treatment]
Refractive errors assessed with Pentacam HR Schempflug Camera and iTrace, Diopters
- Change from baseline in spherical equivalent [1 month, 3 months, 6 months, 12 months and 24 months after treatment]
Change from baseline in spherical equivalent on subjective distance refraction, Diopters
- Change from baseline in corneal endothelial cell density [24 months after treatment]
Change from baseline in central corneal endothelial cell density, cells/mm2
Eligibility Criteria
Criteria
Inclusion Criteria:
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Patients planned for corneal crosslinking.
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Progressive keratoconus documented with a consistent decrease of best corrected visual acuity with no other explanation, an unquestionable historical progression, or a progression documented with the Pentacam Scheimpflug camera with at least 2 of the following: progressive anterior and/or posterior corneal steepening and/or progressive corneal thinning and/or increased rate of corneal thickness change from the periphery to the center.
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A keratoconus diagnosis based on abnormal posterior elevation, abnormal corneal thickness distribution and clinical noninflammatory corneal thinning using the "Belin/Ambrósio enhanced ectasia" measurements of the Pentacam Scheimpflug camera.
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Minimum corneal thickness of 400 µm at the thinnest point before epithelial removal.
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18-35 years of age
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No ocular abnormalities except keratoconus
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No previous ocular surgery
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No cognitive insufficiency interfering with the informed consent.
Exclusion Criteria:
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Age under 18 or over 35
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Any corneal abnormalities except keratoconus
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Pregnancy or lactation
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Previous ocular surgery
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Cognitive insufficiency
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Department of Clinical Sciences/Ophthalmology, Umeå University | Umeå | Sweden | 901 85 |
Sponsors and Collaborators
- Umeå University
- Glaukos Corporation
Investigators
- Principal Investigator: Anders Behndig, MD, PhD, Department of Clinical Sciences/Ophthalmology, Umeå University
Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- PiXLKC-I