Coloured-light in Retinitis Pigmentosa.

Retinitis Pigmentosa Clinical Trial

— CLIRP  

Official title:

A Pilot, Randomised, Masked Study to Investigate the Effect of Coloured-light on Colour Contrast Thresholds in Retinitis Pigmentosa.

Clinical Trial Details — Status: Not yet recruiting

Administrative data

• NCT number: NCT06224114
• Other study ID #: 161090
• Status: Not yet recruiting
• Phase: N/A
• Start date: March 2024
• Est. completion date: October 2024

Study information

• Verified date: January 2024
• Source: University College, London
• Contact: Pushpsen Joshi
• Phone: 0203 447 5369
• Email: uclh.randd[@]nhs.net
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This study will assess the effect of 2 different colours of light on colour vision in adults with retinitis pigments (RP). Participants will be 18 years or above with a genetically confirmed molecular diagnosis of RP. After informed consent, participants will have their letter chart vision and colour vision measured in their study eye. They will then be they will be randomly allocated to one of 2 groups. The study team will not know which group they have been assigned to. Group 1 will be given a coloured-light hand-held torch and be asked to apply it to their study eye for 3 minutes at home each morning between 8 - 10 am for 28 days. Group 2 will be given a different colour hand-held torch and be asked to do the same. All participants will have their letter chart vision and colour vision measured at the end of study on day 28 (+ 7 days).

Description:

This is a pilot, randomised, masked, single-site trial designed to assess the effect of coloured light exposure on cone contrast thresholds (CCT) in adults with RP.

70 adults with typical RP in which the underlying genetic cause is known will be recruited from Moorfields Eye Hospital genetics service.

Following informed consent, participants will be invited for a baseline study visit.

At a baseline visit, prior to any light exposure (day 0), participants will undergo Logarithm of the Minimum Angle of Resolution (LogMAR) visual acuity (VA) and CCT measurements performed by an experienced technician according to dedicated standard operating procedures. The order of testing will be as follows:

• Study eye: LogMAR VA

• Study eye: CCT (Tritan and Protan)

After baseline assessments have been completed, participants will be randomised to the intervention (n=35) or control group (n=35) by a study nurse. All other study team members will be masked to group allocation.

The intervention group will be provided with a coloured torch and instructed to apply it to their study eye for 3 minutes at home each morning between 8 - 10 am for 28 days. The control group will be provided with a different coloured torch and will be instructed to follow the same protocol. The specific colours have not be disclosed here to protect masking of the study. Participants will be asked to complete a paper diary each day to record whether light was applied, the time and duration of the application and the eye to which light was applied.

The end of trial visit will be scheduled on day 28 (+7 days). Participants will undergo LogMAR VA and CCT measurements by an experienced technician according to standard operating procedures (SOP). The order of testing will be as follows:

• Study eye: LogMAR VA

• Study eye: CCT (Tritan and Protan)

Recruitment information / eligibility

• Status: Not yet recruiting
• Enrollment: 70
• Est. completion date: October 2024
• Est. primary completion date: October 2024
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

• Over 18 years old

• Typical RP where the underlying genetic cause is known. This may include PRPF31, PRPF8, SNRNP200, RHO, RP1 [autosomal dominant] and USH2A, EYS [autosomal recessive]

• VA of 0.30 LogMAR (6/12) or better in the study eye

• Preserved foveal structure defined by intact outer retinal (ellipsoid zone) at the fovea on Optical Coherence Tomography (OCT) and a hyperfluorescent ring within the temporal vascular arcades on Fundus Autofluorescence (FAF) in the study eye

• Willing and able to provide written informed consent

Exclusion Criteria:

• Co-existing ocular pathology will be excluded; however, participants with macular oedema, a common pre-symptomatic manifestation of foveal involvement, will not be excluded

• Concurrent and/or recent involvement in other research that is likely to interfere with the intervention within 6 months of study enrolment

• Unwilling or able to provide written informed consent.

Related Conditions & MeSH terms

• Retinitis
• Retinitis Pigmentosa

Intervention

Device:
• Coloured-light torch
Participant administered, at-home, 3-minute daily morning application (between 8 - 10am) of a coloured-light torch to the study eye.
• Different coloured-light torch
Participant administered, at-home, 3-minute daily morning application (between 8 - 10am) of a different coloured-light torch to the study eye.

Locations

Country	Name	City	State
United Kingdom	Moorfields Eye Hospital NHS Foundation Trust	London

Sponsors (1)

Lead Sponsor	Collaborator
University College, London

Country where clinical trial is conducted

United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Tritan Colour Contrast Threshold (CCT)	Tritan CCT will be measured using the ChromaTest® platform, a software program which quantifies age-corrected tritan and protan CCT using a Modified Binary Search method. Tritan CCT test endpoint is a continuous variable (units: percentage).	Measured at Day 0 and Day 28
Secondary	Protan CCT	Protan CCT will be measured using the ChromaTest® platform, a software program which quantifies age-corrected tritan and protan CCT using a Modified Binary Search method. Protan CCT test endpoint is a continuous variable (units: percentage).	Measured at Day 0 and Day 28
Secondary	LogMAR Visual Acuity (LogMAR VA)	LogMAR VA will be measured on an electronic LogMAR acuity chart (Test Chart 2020, Thompson Software Solutions, UK), according to a forced-choice procedure.	Measured at Day 0 and Day 28
Secondary	Proportion of participants losing =15 letters of LogMAR VA	Proportion of participants losing 15 letters of LogMAR VA or more at day 28 will be reported as a safety outcome.	Measured each day (Day 0 through Day 28)
Secondary	Compliance rate	Compliance rate of application of daily, 3-minute, at-home, participant administered coloured-light exposure is a secondary endpoint. This will be collected through completion of a participant diary.	Measured each day (Day 0 through Day 28)