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How precise do precision tints have to be and how many are necessary?
Arnold Wilkins1, Nirmal Sihra, Ian Nimmo Smith
1Department of Psychology, University of Essex, Colchester, UK. arnold@essex.ac.uk
Summary
Reading speed is affected by light color and tint chromaticity. Optimal tint effectiveness requires over 1000 trial tints for ophthalmic systems to achieve >95% efficacy.
Area of Science:
- Optometry
- Color Science
- Human Factors
Background:
- Reading speed is influenced by light chromaticity in individuals wearing precision tints.
- Tint effectiveness diminishes as light chromaticity deviates from optimal reading conditions.
Purpose of the Study:
- To quantify how variations in tint color under different lighting conditions affect reading speed.
- To determine the number of tints an ophthalmic tinting system must provide for optimal efficacy.
Main Methods:
- Analysis of 1000 recent ophthalmic prescriptions.
- Evaluation of reading speed variations based on chromaticity in the CIE 1976 UCS diagram.
- Modeling the relationship between desired efficacy and the number of required trial tints.
Main Results:
- Tint color variation under different illuminations reduces but does not eliminate tint benefits.
- A minimum distance of approximately 0.08 in the CIE 1976 UCS diagram indicates minimal residual benefit.
- Achieving >95% optimal efficacy necessitates over 1000 trial tints, achievable through lens combinations and dyeing techniques.
Conclusions:
- Ophthalmic tinting systems require a large number of trial tints to maintain high efficacy across various lighting conditions.
- Practical implementation involves combining existing trial lenses and advanced dyeing methods to meet the demand for numerous tints.