Clinical trial NCT04060238: Effect of Protanopia on the Brightness Perception of Brake Lights
Official title: Investigation of the Effect of Protanopia ("Red Blindness") on the Brightness Perception of Brake Lights and Their Effect on Reaction Time
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Color Blindness, Red
Reaction Time
Keywords: protanopia
taillight
brake light
differential luminance sensitivity
contrast sensitivity
colour vision
colour vision defect
perimetry
semi-automated kinetic perimetry
traffic
motorist
reaction time
Lead sponsor: Aalen University
Sponsor class: OTHER
Collaborators: name: Karlsruhe Institute of Technology (KIT), Karlsruhe/FRG
First posted: 2019-08-19
Enrollment: 16
Sex: MALE
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Observational model: CASE_CONTROL
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Ophthalmologically normal (male) subjects OR (male) subjects with (inherited) protanopia (red blindness)

Brief summary: The aim of the offered project is to investigate the influence of protanopia (red blindness) or protanomaly (red vision weakness) on the recognizability of red brake lights with the help of a test person study. From this, estimates of the influence of protanopia or protanomaly on driving ability are to be derived.

If a relevant influence can be demonstrated in the study, recommendations for action for the legislator will be made.

Translated with www.DeepL.com/Translator

Detailed description: Protanopia is an x-chromosomal inherited cone pigment disorder that related to the red cone,i.e. the L-cone function completely fails. The prevalence of protanopia in the male population is 1%. An incomplete impairment of the L-cone is called protanomaly. The prevalence here is also in 1% of the male population.

In comparison to persons with normal vision red objects appear darker for persons with missing or functionally limited L-cones. This is particularly critical in road traffic, where red is used as a signal colour, for example in traffic lights or brake lights is used.

The scientific questions that need to be investigated are as follows:

1. At which contrast threshold (relative brightness) does a proband with protanopia recognize a brake light compared to a normal person?
2. If the luminance determined is above the contrast threshold, what influence does the excess of the contrast or the determined luminance have on the reaction time?
3. Are there differences with regard to the technology used in the brake light (incandescent lamp or LED)?

For this purpose, a representative set of combination rear lamps, focusing on stoplight, taillight (and of the elevated brake light) in a static situation is created. The test setup is based on a driving pursuit scenario. The test person is positioned at a relevant distance to the combination of rear lamps.

To determine the threshold contrast, an algorithm is developed to control the relative brightness of the brake lights and integrated into the test sequence control. In addition, a method for automated determining of the related reaction time is implemented.

Two taillight technologies (incandescent lamp and LED) are examined at both ambient brightness levels: (i) "bright", i.e. photopic luminance level (Lu \>\> 10 cd/m2) and (ii) "dark", i.e. mesopic luminance level (Lu \< 10 cd/m2).

A comprehensive ophthalmological/optical examination (including visual acuity, ocular alignment, ocular motility, assessment of the leading eye, testing of the efferent and afferent pupillary system and biomicroscopic inspection of the anterior and posterior segments of the eye) is carried out. Comprehensive colour vision testing it performed with the HMC anomaloscope, Oculus Inc., Dutenhofen/FRG, including assessment of the loss of brightness sensation during anomaloscopic exam with max. red. stimulus . In addition, standardized semi-automated kinetic perimetry (SKP) along the horizontal meridian with an automated perimeter (Octopus 900, Haag-Streit Inc., Koeniz/CH) is performed. The ratio of the horizontal extent ("diameter") obtained with both, red vs. white stimuli, is measured and taken as a clinical parameter for quantifying the magnitude of the individual "protan colour vision deficiency".

To illustrate the worst-case scenario, this study is limited to protanopic patients. It is intended as a pure comparative study between a "protanopic" patient group and a "normal vision" control group. The protanopic test subjects and the control subjects are matched with regard to gender and age.

This study is carried out in a "within-subject design", i.e. all test persons go through all situations. In order to minimize sequence effects, the related test conditions are randomized.

Eligibility criteria: Inclusion Criteria:

* informed consent
* male
* age (greater or equal) 18 years

Exclusion Criteria:

* binocular (high contrast) distant visual acuity worse than 0.8 (16/20)
* spherical ametropia exceeding 8 dpt
* cylindrical ametropia exceeding 2.5 dpt
* manifest strabismus (squint) with diplopia
* relative afferent pupillary defect exceeding 0.3 log units
* anamnestic (patient history) OR morphological (slit lamp --\> anterior segment, ophthalmoscope --\> retina) clue/indicator for a ophthalmologically relevant affection of the eye OR the visual pathway
* S.p. severe ocular trauma
* Current OR s.p. severe intraocular inflammation
* S.p. intraocular surgery within the past three months

Primary outcomes:
measure: Contrast sensitivity (I)
timeFrame: within one year
Secondary outcomes:
measure: Reaction time
timeFrame: within one year
measure: Contrast sensitivity (II)
timeFrame: within one year
measure: Reaction time (II)
timeFrame: within one year
measure: Perimetric extent of horizontal meridian
timeFrame: within one year
measure: Loss of brightness sensation during anomaloscopic exam
timeFrame: within one year
Other outcomes:
Locations:
city: Aalen
country: Germany
facility: Ulrich SCHIEFER
state: Deutschland
Study officials:
affiliation: Aalen University of Applied Sciences
name: Ulrich Schiefer, MD
role: STUDY_CHAIR
References: