PiXL for Correction of Hyperopia


This clinical study aims to investigate the efficacy and safety of PiXL in the refractive correction of low hyperopia.

Full Title of Study: “Photorefractive Intrastromal Corneal Crosslinking (PiXL) for Correction of Hyperopia”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: N/A
    • Intervention Model: Single Group Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: December 2018

Detailed Description

This clinical study aims to investigate the efficacy and safety of PiXL in the refractive correction of low hyperopia.Slightly modified settings from previously published study is applied to eyes with low hyperopia with an expected refractive change of 0.75 D. Aim is to evaluate the refractive outcome of this procedure.


  • Radiation: PiXL
    • The system is set to deliver 30 mW/cm2 UVA irradiance in pulsed intervals of 1 second on and 1 second off to 5 to 9 mm diameter corneal annulus. Total energy delivered is 15J.

Arms, Groups and Cohorts

  • Experimental: Photorefractive intrastromal corneal crosslinking (PiXL)
    • Patients undergo PiXL where the UVA light is delivered in customized patterns and corneal changes are achieved. For hyperopia, a ring shape irradiation is used to steepen the central cornea. An oxygen mask is used to enhance the crosslinking efficacy. A dedicated riboflavin formulation penetrates the corneal stroma. Pulsed UVA light with oxygen triggers the covalent bonds of collagen strands in riboflavin soaked cornea.

Clinical Trial Outcome Measures

Primary Measures

  • Change in Uncorrected Distance Visual Acuity
    • Time Frame: Month 12
    • Best distance visual acuity tested without any correction
  • Change in Subjective Refraction
    • Time Frame: Month 12
    • Spherical and cylindrical correction

Secondary Measures

  • Change in keratometry
    • Time Frame: Month 12
    • Change in keratomery parameter K2-K1provided by Pentacam
  • Change in Higher Order Aberrations
    • Time Frame: Month 12
    • Higher Order Aberrations assessed using Pentacam
  • Change in pachymetry
    • Time Frame: Month 12
    • Change in mean cornea thickness in 8.0 mm ring provided by Pentacam
  • Subjective questionnaire score
    • Time Frame: Month 12
    • Questionnaire assessing participants discomfort at 6 months in respect to their photophobia, pain and dry eye.
  • Change in Corrected Distance Visual Acuity
    • Time Frame: Month 12
    • Best distance visual acuity tested with the best correction
  • Change in Spherical aberration
    • Time Frame: Month 12
    • Spherical aberration assessed using Pentacam

Participating in This Clinical Trial

Inclusion Criteria

  • low hyperopia of spherical equivalent from +0.5 up to +1.75 D sp. eq.
  • astigmatism up to 0.75 Dcyl
  • corneal thickness above 400 ┬Ám
  • endothelial cell density above 1500 cell/mm2

Exclusion Criteria

  • any prior corneal surgery or any eye surgery within the last 3 months,
  • any corneal pathology e.g. corneal scar or dystrophy
  • unstable refraction
  • patient not able to understand and sign informed consent
  • patients with connective tissue disorder or uncontrolled diabetes
  • pregnant or lactating women
  • aphakic eyes or pseudophakic eyes without UV blocking IOL

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Gemini Eye Clinic
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Pavel Stodulka, MD, PhD, Principal Investigator, Gemini Eye Clinic


Kanellopoulos AJ, Asimellis G. Hyperopic correction: clinical validation with epithelium-on and epithelium-off protocols, using variable fluence and topographically customized collagen corneal crosslinking. Clin Ophthalmol. 2014 Dec 2;8:2425-33. doi: 10.2147/OPTH.S68222. eCollection 2014.

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