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.
The study is designed as a prospective, single-masked intraindividually comparing randomized clinical 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 32 participants with bilateral Keratoconus, receiving Epi-off PiXL (n=32) in one eye and Epi-on PiXL in high oxygen environment (n=32) in the fellow eye. The participants are randomized to epi-on PiXL utilizing block randomization with a sample size of 16 in each block; 16 right eyes and 16 left eyes. All participants 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 using Schemipflug camera measurements, Pentacam HR® (Oculus, Inc. Lynnwood, WA). Endothelial cellcount is assessed (SP-2000P, Topcon, Inc) 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 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 and slit-lamp examination are evaluated.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
32
Photorefractive intrastromal crosslinking (PiXL) After local anaesthetics, the 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; \< 45D, 7.2J/cm2; 45-50D, 10J/cm2; \> 50D, 15 J/cm2.
Photorefractive intrastromal crosslinking (PiXL) After local anaesthetics, the corneal epithelium is debrided and the cornea is soaked in Riboflavin by repeated topical application during 10 minutes. The cornea is then illuminated with individually customized topography-guided PiXL under 16:40 minutes. The UV-dosage is individually customized based upon Kmax; \< 45D, 7.2J/cm2; 45-50D, 10J/cm2; \> 50D, 15 J/cm2.
Department of Clinical Sciences/Ophthalmology, Umeå University
Umeå, Sweden
Maximal keratometry (Kmax)
Kmax assessed with the Pentacam HR Scheimpflug camera, Diopters.
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Uncorrected distance visual acuity (UDVA)
Change from baseline in distance uncorrected visual acuity, LogMAR
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Best corrected visual acuity (BCVA)
Change from baseline in distance best corrected visual acuity, LogMAR
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Mean keratometry (Kmean)
Kmean (average) assessed with the Pentacam HR Scheimpflug camera, Diopters.
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Subjective Ocular Discomfort Scores
Subjective Ocular Discomfort Scores, Visual Analog Score (0 (no discomfort) - 10 (maximum discomfort)) for each eye, mm.
Time frame: 4 hours, 8 hours, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days and 7 days after treatment
Low contrast visual acuity (LCVA)
Change from baseline in low contrast visual acuities at 10 % and 2.5 % contrast, LogMAR
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Manifest spherical equivalent (MRSE)
Change from baseline in spherical equivalent on subjective distance refraction, Diopters
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Central corneal thickness (CCT)
Change from baseline in central corneal thickness assessed with Pentacam, Scheimpflug camera, μm.
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Change from baseline in ocular wavefront aberrometry
Change from baseline in higher order aberrations assessed with iTrace, Root mean square.
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
Endothelial cell density (ECC)
Change from baseline in endothelial cell density, cells/mm2
Time frame: 24 months after treatment
Intraocular pressure (IOP)
Change from baseline in intraocular pressure assessed with Goldmann applanation tonometry, mmHg.
Time frame: 1 month, 3 months, 6 months, 12 months and 24 months after treatment
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