Colorblindness Solutions at Edridge Green Lantern

The 'Edridge Green Lantern' (or Lantern of Edridge Green) is a historical and contemporary tool for testing color vision, particularly for red-green color blindness. It is widely utilized in transportation (rail, aviation, marine) and industry to screen personnel for safety-critical roles by simulating realistic signal light conditions with colored filters and adjustable apertures. Developed by E.J. Edridge Green, this lantern replaced older wool tests in the UK and remains essential for occupational vision assessment. How it Works

Colored Filters: The lantern presents red, green, and white lights, sometimes modified, to closely mimic real-world conditions. 

Rotating Discs: It uses several discs with colored glasses, apertures, and modifiers that the examiner rotates. 

Testing Process: The candidate calls out the colors they see as the examiner changes combinations, revealing any color perception defects.

Purpose & Use

Occupational Screening: This tool is crucial for jobs where accurate color signals matter, such as pilots, train drivers, and sailors. 

Standardized Testing: It provides reproducible results for medical, psychological, and industrial evaluation, complementing other assessments like the Ishihara test. The Ishihara color vision chart is often used alongside the Edridge Lantern to provide a comprehensive analysis of color vision. 

Training: It is also utilized in educational settings to train vision.

Key Features

Realistic Simulation: Filters and apertures simulate atmospheric effects and distance. 

Portable: Designed for use in clinics and the field. 

Reliable: Offers standardized, valid, and repeatable testing.

MARTIN LANTERN TEST

The Martin Lantern Test is a practical, real-world simulation test for color vision, particularly for red-green deficiencies. It is used for jobs like pilots, seamen, and railway personnel, where candidates identify red, green, and white lights shown briefly in pairs, mimicking signal lights, to check if they can distinguish crucial navigational colors under time pressure. This approach contrasts with static plate tests like the Ishihara chart, which include the Ishihara book 38 plates pdf download for reference. It assesses functional color vision for safety-critical roles, not just theoretical color defects. How it Works

Device: A lantern featuring colored lights (red, green, yellow/white) and various apertures. 

Procedure: The subject sits at a specific distance (e.g., 1.5m) and identifies colors presented in pairs or individually for short durations (around 2 seconds). 

Goal: To determine if the person can correctly identify colors, especially distinguishing red/green and white, under realistic conditions where prolonged viewing isn't an option. 

Scoring: Based on correct identifications, with specific criteria for passing or failing, often classifying the level of color vision deficiency (CP I, CP III).

Why it's Used

Functional Test: It evaluates what a person can do with color vision in a job, not just if they have a defect. 

Simulates Real Conditions: This test mimics seeing signal lights, which is crucial for aviation, maritime, and rail safety. 

Complements Other Tests: The Martin Lantern Test is frequently used alongside tests like the Ishihara or Farnsworth D15 to provide a complete picture of color vision ability.

Key Takeaway: If you're colorblind, passing the Martin Lantern Test can often mean you're fit for roles requiring color vision (like being a pilot), as it demonstrates your ability to perform necessary color discrimination tasks in real-world scenarios.