Condition category
Eye Diseases
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Keratoconus is an eye condition in which the normally round dome-shaped clear window of the eye (cornea) becomes thinner and changes shape over time, leading to poor vision. Symptoms of keratoconus generally begin in late teenage years or early twenties but they can start at any age. If it is spotted during childhood, it is often more advanced and worsens more quickly. Patients with a suspected or confirmed diagnosis of keratoconus are usually referred to hospital clinics immediately or when they first go to get glasses. In advanced cases, a transplant surgery to replace the affected cornea is needed. Corneal collagen cross-linking (CXL) is a procedure that involves the removal of the surface layer of the cornea, the administration of riboflavin (vitamin B2) eye drops and exposure of the cornea to UV light. CXL is a new treatment that is believed to stop keratoconus from getting worse, by increasing stiffness of the cornea and stopping progression. The aim is to study the efficacy and safety of (CXL) in children with keratoconus, and to compare it to standard care with provision of glasses and/or contact lenses as required for best vision.

Who can participate?
Children aged between 10 and 16 years with mild to moderate keratoconus

What does the study involve?
Participants are randomly allocated to one of two groups. Those in the first group continue to receive normal care, which involved being given glasses or contact lenses to correct their vision. Those in the second group undergo the CXL procedure. This involves having the area numbed (local anaesthetic) or being put to sleep (general anaesthetic) for the operation, in which the surface layer of the cornea is removed, vitamin B2 eye drops applied and ultraviolet light shone on the eye. Participants in both groups have their eyes examined at the start of the study and then every three months for 18 months in order to assess progression of their condition.

What are the possible benefits and risks of participating?
It is not known whether there will be any benefits involved with participating. There is a risk that some patients treated with CXL will experience pain in the treated eye 1-2 days after the procedure. There is always a risk when having surgery, most of the time these are very mild (such as feeling nauseous, tired or dizzy from the anaesthetic).

Where is the study run from?
1. Moorfields Eye Hospital (UK)
2. Royal Hallamshire Hospital (UK)
3. Royal Liverpool Hospital (UK)

When is the study starting and how long is it expected to run for?
September 2015 to February 2019

Who is funding the study?
National Institute for Health Research (UK)

Who is the main contact?
Dr Haripriya Tumuluri

Trial website

Contact information



Primary contact

Dr Haripriya Tumuluri


Contact details

Comprehensive Clinical Trials Unit
University College London
Gower Street
United Kingdom
+44 7464 498627

Additional identifiers

EudraCT number

2016-001460-11 number

Protocol/serial number


Study information

Scientific title

Corneal cross-linking versus standard care in children with keratoconus, a randomised, multicentre, observer-masked trial of efficacy and safety



Study hypothesis

The aim of KERALINK is to establish clear evidence on whether CXL is efficacious in stabilising the progression of keratoconus and safe in children and young patients between the age of 10 and 16 years.

Ethics approval

London-Brent Research Ethics Committee, 30/06/2016, ref: 16/LO/0913

Study design

Randomised; Interventional; Design type: Treatment, Drug

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Specialty: Ophthalmology, Primary sub-specialty: Other; UKCRC code/ Disease: Eye/ Disorders of sclera, cornea, iris and ciliary body


Participants are randomised into one of two groups in a 1:1 ratio using computer generated treatment group allocation

Intervention group: Participants receive cross-linking in one or both eyes (according to whether progression is confirmed in one eye or both eyes), under general or local anaesthesia as applicable, followed by standard management. Following removal of corneal epithelium and administration of riboflavin drops, ultraviolet light will be administered according to standardised parameters of 10mW/cm2 for a 5.4J/cm2 total energy dose.

Control group: Participants receive standard management alone, including refraction testing with provision of glasses and/or specialist contact lens fitting. Glasses or contact lenses to be provided for one or both eyes as required for best corrected visual acuity. Those patients who develop advanced disease and poor spectacle- and lens-corrected visual acuity during the course of the trial will be offered corneal transplantation.

Follow up for all participants takes place at every 3 months and involves examination of the study eye using Corneal Topography, Refraction and Corneal Ultrasound techniques.

Intervention type



Drug names

Primary outcome measure

Keratoconus progression is assessed by measuring Kmax by Pentacam at baseline and 18 months.

Secondary outcome measures

1. Time to keratoconus progression is measured using Pentacam at baseline, post-treatment, 3, 6, 9, 12, 15 and 18 months
2. Uncorrected and best corrected visual acuity is measured using a Standard Eye Chart at baseline, post-treatment, 3, 6, 9, 12, 15 and 18 months
3. Refraction is measured using a Retinoscope at baseline, post-treatment, 3, 6, 9, 12, 15 and 18 months
4. Apical corneal thickness is measured using ultrasound at baseline, post-treatment, 3, 6, 9, 12, 15 and 18 months
5. Quality of life as assessed by using the CHU9D and CVAQC questionnaires at baseline, 6, 12 and 18 months

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Age 10-16 years
2. With keratoconus progression confirmed in one or both eyes by Pentacam cornealtopography. Progression will be defined as an increase of at least 1.5 dioptres in Kmax on corneal topography between two Pentacam examinations at least 3 months apart.
3. Provision of informed consent and willingness to complete the patient reported outcome measures
4. Willing to attend for follow up visits

Participant type


Age group




Target number of participants

Planned Sample Size: 60; UK Sample Size: 60

Participant exclusion criteria

1. Advanced keratoconus as determined by apex corneal scarring
2. Apex corneal thickness 60 diopres
3. Rigid contact lens wear in both eyes and unable to abstain for 7days pre-examinations
4. Corneal co-morbidity
5. Down's syndrome
6. Any clinical condition which the investigator considers would make the patient unsuitable for the trial, including pregnancy
7. Participation in other clinical trials which would materially impact on the Keralink study

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Moorfields Eye Hospital
City Road
United Kingdom

Trial participating centre

Royal Hallamshire Hospital
8 Beech Hill Road
S10 2SB
United Kingdom

Trial participating centre

Royal Liverpool Hospital
Prescot Street
Prescot St
United Kingdom

Sponsor information


University of London

Sponsor details

Comprehensive Clinical Trials Unit
Gower Street
United Kingdom

Sponsor type

Hospital/treatment centre



Funder type


Funder name

National Institute for Health Research

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

Federal/National Government


United Kingdom

Results and Publications

Publication and dissemination plan

Not provided at time of registration

IPD sharing statement:
The datasets generated and/or analysed during the current study during this study will be included in the subsequent results publication.

Intention to publish date


Participant level data


Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

31/10/2017: Internal review.