Wearable Dark-adaptometer in Normal Adult Healthy Volunteers

Completed

Conditions: Photoreceptor Sensitivity Thresholds

Interventions: Device: Dark Adaptometer

Registration Number: NCT02674425

Lead Sponsor: University of Liverpool

Brief Summary: Conventional dark-adaptometers are unsuitable as a mass screening tool due to their high cost, lack of easy portability, need of trained staff and a totally dark room to be operated, arbitrary testing procedures, associated time waste in clinic and patient burden to mention a few. Consequently, dark adaptometers are not routinely used as clinical tools for retinal diagnosis and monitoring despite the inherent benefits over other visual electrophysiology equipment such as the ERG system, whose cost and features may often be surplus to optometrists' requirements.

This trial will assess the dark-adaptometry testing performance of a novel light-emitting system by generating full dark-adaptation threshold functions in normal adult healthy volunteers.

The novel system has been proposed to overcome the issues associated with current instrumentation; it is semi-automatic and easy to use without the need of any skilled operator.

It is envisaged that this system could spread the practice of dark-adaptometry testing and its adoption by high-street optometrists. This will allow diagnosing a number of retinal pathologies more quickly and more reliably that, faced with an ageing population, represents a major asset to the Health Community and the NHS.

This trial will involve 20 healthy volunteers, distributed in equal number in 2 groups of 18-40 and 50-70 years old, respectively. Proven the good health and eye condition of the participants, one of their eyes will be randomly-allocated and undergo dark-adaptometry testing 3 times on separate days within 3 weeks.

Testing will clarify whether by using the novel system it is possible to reproduce state-of-the-art threshold measurements as good or better than those produced by commercially-available dark-adaptometers. Threshold measurements in the elderly will be compared with literature data adjusted to exclude aged crystalline lens and pupillary miosis contributions. Data variability and system usability will be also assessed.

Detailed Description: All details elsewhere in the documentation

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 20

Inclusion Criteria

Refractive error: ≤ ±5 dioptres spherical (myopia/hyperopia) equivalent; ≤ 3 dioptres cylinder (astigmatism) equivalent.

Exclusion Criteria

Subjects not in age range and/or unable to fully understand the informed consent and/or unable to comply with study procedures.
Self-reported history of depression, lack of sleep, psychiatric disorders, or neurological diseases such as Alzheimer's and Parkinson's disease.
Self-reported history of diabetes, stroke, or multiple sclerosis.
Self-reported hypovitaminosis A, alcoholism, liver or intestinal disease, malabsorption, protein calorie malnutrition, or sickle cell anaemia.
Use of psychoactive drugs (including lithium salts for mood stabilisation).
Use of dietary intake of ascorbic acid, vitamin A, B, E or other antioxidant supplements in the last two weeks.
Recurrent practice of activities that expose the retina to ultra-violet radiation such as sailing, fishing, sunbathing or tanning saloons.

Study & Design

Study Type: OBSERVATIONAL

Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Young adults (18-40)	Dark Adaptometer	Healthy adult volunteers, aged between 18 and 40, with no prior/current eye problems or family history of genetic eye diseases and good general health.
Older adults (50-70)	Dark Adaptometer	Healthy adult volunteers, aged between 50 and 70, with no prior/current eye problems or family history of genetic eye diseases and good general health.

Primary Outcome Measures

Name	Time	Method
Absolute Threshold	40 minutes	Rod sensitivity (absolute threshold luminance) values measured in cd\*m-2
Absolute Threshold Time	40 minutes	Time taken to reach absolution threshold measured in minutes
Time to Rod-cone Break (RCB)	40 minutes	RCB (time) values were determined by recording the time required for the participant to observe a light stimulus of a particular luminosity. Participants viewed the light stimuli without their optical correction. These consisted of a white (λpeak = 464 nm; chromaticity coordinates - 2° observer: x = 0.269, y = 0.324) circular test target of 0.255 mm radius, forming a visual angle of around 33°. Participants were asked to press a response button on the handheld joystick when the test target was visible and had 750 ms to make a response after target onset. Target intensity started at approximately 4.865 cd\m-2. Light stimuli were presented approximately every 2.6 s for a duration of 150 ms each. If the subject under test did not respond to the stimuli, the target intensity remained at the same initial level of approximately 4.865 cd\m-2 until the subject responded. If the subject reported perception of the light stimulus within the response window, the luminance was reduced by 0