PiXL as a Treatment for Low Grade Myopia

Myopia Clinical Trial

Official title:

Evaluation of a Reduced Photorefractive Intrastromal Corneal Crosslinking Illumination Protocol. A Randomized Controlled Trial.

Clinical Trial Details — Status: Active, not recruiting

Administrative data

• NCT number: NCT04663048
• Other study ID #: PiXLMYOP-III
• Status: Active, not recruiting
• Phase: N/A
• Start date: February 7, 2019
• Est. completion date: June 17, 2024

Study information

• Verified date: December 2023
• Source: Umeå University
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

To assess the improvement in myopia with phototherapeutic intrastromal corneal collagen cross-linking (PiXL) without epithelial debridement (epi-on) in high oxygen environment for low grade myopia. The study compares two 3.5-mm central ring-shaped zone protocols; 10 min illumination time vs 16:40 min illumination time.

Description:

The study design is a prospective, single-masked intraindividually comparing randomized controlled trial, conducted at the Department of Clinical Sciences / Ophthalmology, Umeå University Hospital, Umeå, Sweden. The study includes healthy men and women with low grade myopia, aged between 18-35 years and involves 25 participants with a myopia of -0.50 to -2.5 diopters (D) and astigmatism of ≤0.75D. All participants are treated with phototherapeutic intrastromal corneal collagen cross-linking (PiXL) without epithelial debridement (epi-on), after topical riboflavin. Both eyes are treated and randomized to receive ultraviolet (UV) light according to PiXL Protocol A in one eye and PiXL Protocol B in the other, which is masked to the participant. Throughout the treatment, humidified oxygen is continuously delivered around the eye using an oxygen mask to achieve an oxygen concentration of ≥95 percentage. Prior to inclusion all participants are informed about the procedures and provide oral and written informed consent.

At baseline, each eye is examined with slit-lamp microscopy, subjective refraction, determination of uncorrected (UCVA), low contrast visual acuity at 2.5 percentage 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, central corneal thickness and after treatment also the depth of demarcation lines, extracted from Schemipflug camera measurements, Pentacam HR® (Oculus, Inc. Lynnwood, WA). Central corneal endothelial photographs are taken with the Topcon SP-2000P specular microscope (Topcon Europe B.V., Capelle a/d Ijssel, the Netherlands), from which the corneal endothelial cell count is manually calculated from a cluster of 25 cells from each photograph. Total ocular wavefront is measured with iTrace (Tracey Technologies, Inc.).

All the above mentioned examinations are reassessed at 1, 3, 6 and 12 months after treatment. At 1 day and 1 week after treatment, solely UCVA, Auto refractor measurements, slit-lamp examination and a subjective comparison of discomfort and visual performance in each eye are evaluated.

Recruitment information / eligibility

• Status: Active, not recruiting
• Enrollment: 26
• Est. completion date: June 17, 2024
• Est. primary completion date: June 17, 2024
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 35 Years

Eligibility

Inclusion Criteria:

• Spherical equivalent on distance subjective refraction between -0.50D and -2.50D.

• Astigmatism = 0.75D

• Stable myopia. Maximum change in refraction of 0.50D in the last 2 years.

• Best corrected visual acuity of at least 0.00 logMAR (ETDRS chart).

• Thinnest pachymetry reading = 440 µm.

• No previous ocular surgery.

• No cognitive insufficiency interfering with the informed consent.

Exclusion Criteria:

• History of or current condition, disease, surgery or medication with ocular effects that could affect the outcomes of the treatment.

• Allergy to any substance or device used in the study.

• Cognitive insufficiency interfering with the informed consent

Related Conditions & MeSH terms

• Myopia
• Refractive Errors

Intervention

Procedure:
• PiXL
Phototherapeutic intrastromal corneal collagen cross-linking (PiXL) performed in a high-oxygen environment without corneal epithelial debridement, for treatment of low grade myopia.

Locations

Country	Name	City	State
Sweden	Umeå University Hospital	Umeå

Sponsors (2)

Lead Sponsor	Collaborator
Umeå University	Glaukos Corporation

Country where clinical trial is conducted

Sweden, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Uncorrected distance visual acuity (UDVA)	Change from baseline in UDVA (logMAR)	1, 3, 6 and 12 months after treatment.
Primary	Manifest Refractive Spherical Equivalent	Change from baseline in MRSE (Diopters)	1, 3, 6 and 12 months after treatment
Secondary	Best spectacle corrected visual acuity (BSCVA)	Change from baseline in BSCVA (logMAR)	1, 3, 6 and 12 months after treatment
Secondary	Endothelial cell density (ECC)	Change from baseline in ECC (cells/mm^2)	1, 3, 6 and 12 months after treatment
Secondary	Low contrast visual acuity at 10% and 2.5% (LCVA)	Change from baseline in LCVA 10 % and 2.5% (logMAR)	1, 3, 6 and 12 months after treatment