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Completed

NCT Number: NCT03531047

Refractive Corneal Cross-linking for Progressive Keratoconus

Young patients with keratoconus face two problems: disease progression and corneal shape irregularity. Both underlie the 20% rate of corneal transplantation in keratoconics required to maintain useful vision.

Corneal collagen cross-linking (CXL) is a now the gold-standard treatment to halt disease progression. The aim is to strengthen the cornea to prevent further shape deterioration. For patients whose quality of vision has already suffered, standard CXL can generally only prevent further deterioration, rather than improving vision. Refractive CXL, a new iteration of CXL in which a bespoke treatment pattern is applied to the cornea, aims to smooth out surface irregularities thereby improving vision.

This primary objective of this study is to compare the visual outcome in patients with progressive keratoconus treated with refractive CXL, as compared with historical controls treated with standard CXL.

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Key information

Conditions

Keratoconus Corneal Diseases Eye Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Moorfields Eye Hospital NHS Foundation Trust

London, EC1V 2PD, United Kingdom

About this study

Irregular astigmatism (irregular corneal shape leading to irregular focus) is a common cause of failure to achieve an adequate spectacle correction for many patients with corneal disease. For patients affected, rigid gas permeable contact lenses are the only means of visual rehabilitation. Not all patients tolerate rigid contact lens wear, and those that do are often uncomfortable and have a restricted wearing time.

Keratoconus, in which the corneal shape becomes progressively steeper and more irregular in the 2nd to 4th decades of life, is a common cause of irregular astigmatism. Disease progression in keratoconus can be stabilised with corneal collagen cross-linking (CXL), effective in 90% of cases. Pre-existing irregular astigmatism often remains after CXL, with many patients requiring rigid gas permeable contact lenses to regain good vision.

The investigators have recently demonstrated improvements in vision following simultaneous combined cross-linking with laser refractive surgery (TransPRK/CXL). The excimer laser is used to create a smoother, more regular focusing shape on the cornea to improve the quality of vision achieved in spectacles. Although effective, the downsides of using this approach are both the cost and limited availability of excimer laser equipment in the National Health Service (NHS) in the United Kingdom. Also, excimer laser smoothing works by removing corneal tissue. It is not yet known whether this tissue removal will have any detrimental effect on corneal shape stability post CXL.

As a cheaper and potentially more widely accessible alternative, refractive CXL aims to regularise the corneal surface by applying a bespoke treatment pattern based on pre-operative corneal surface shape (topography) scans. At least two-thirds of patients undergoing standard CXL already have impaired vision at the time treatment. The investigators are aiming to offer these patients both long-term stability of their keratoconus and an improvement in vision in a single treatment.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients with progressive stage I - III keratoconus
  • Corrected distance visual acuity (CDVA) < 0.00 logMAR

Exclusion criteria

  • Patients under the age of 18 years
  • Active ocular surface disease
  • Minimum corneal thickness < 375 µm
  • Vulnerable groups
  • Pregnancy

Treatment and study plan

Customised CXL

Procedure

As for standard CXL, following mechanical removal of the corneal surface layer (epithelium), 0.1% riboflavin drops will be applied every 2 minutes for 10 minutes prior to ultraviolet A (UVA) irradiation - UVA power, distribution and timing as determined by analysis of Pentacam tomography scans. A bandage contact lens will be applied to encourage regrowth of the corneal surface and reduce post-operative pain.

Other names: Riboflavin drops (drug): Vibex Rapid (Avedro Inc.)

Primary outcomes

  1. Change in corrected distance visual acuity

    Time frame: 24 months

    LogMAR corrected vision in spectacles

Secondary outcomes

  1. Change in uncorrected distance visual acuity

    Time frame: 24 months

    LogMAR uncorrected vision without spectacles

  2. Manifest refraction

    Time frame: 24 months

    Spectacle prescription

  3. Tomography

    Time frame: 24 months

    Corneal Pentacam indices

  4. Rates of keratitis

    Time frame: 24 months

    Complications of CXL

Sponsors and collaborators

Lead sponsor

Moorfields Eye Hospital NHS Foundation Trust

Other

Registry information

Official study title

A Prospective, Controlled Study of Refractive Corneal Cross-linking for Progressive Keratoconus

Important dates

Study start
2018
Primary completion
2019
Study completion
2019
First posted
May 21, 2018
Registry last updated
Dec 8, 2023

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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