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).
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)
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
70
Participant administered, at-home, 3-minute daily morning application (between 8 - 10am) of a coloured-light torch to the study eye.
Participant administered, at-home, 3-minute daily morning application (between 8 - 10am) of a different coloured-light torch to the study eye.
Moorfields Eye Hospital NHS Foundation Trust
London, United Kingdom
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).
Time frame: Measured at Day 0 and Day 28
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).
Time frame: Measured at Day 0 and Day 28
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.
Time frame: Measured at Day 0 and Day 28
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.
Time frame: Measured each day (Day 0 through Day 28)
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.
Time frame: Measured each day (Day 0 through Day 28)
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