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Protection from ultraviolet radiation by spectacle lenses available in India: a comparative study
T Velpandian1, A K Ravi, S S Kumari
1Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi 110029, India. tvelpandian@hotmail.com
The National Medical Journal of India
|January 26, 2006
Summary
Many Indian lenses fail to provide adequate ultraviolet radiation (UVR) protection, particularly UV-A. Glass lenses offer better UV protection than hard resin lenses, but certification is needed.
Area of Science:
- Ophthalmology
- Materials Science
- Photobiology
Background:
- Ultraviolet radiation (UVR) exposure poses risks to ocular health.
- Commonly available uncut lenses in India, including hard resin and glass types, were investigated for UV absorption.
- Study included 20 lenses (11 hard resin, 9 glass) for prescription and non-prescription wear.
Purpose of the Study:
- To assess the UV-A and UV-B absorption capabilities of commonly available lenses in India.
- To compare the UV protection efficacy of hard resin versus glass lenses.
- To evaluate lens compliance with United States Food and Drug Administration (US FDA) recommendations.
Main Methods:
- UV-visible spectrophotometry was employed to scan percentage transmittance from 190 to 400 nm.
- Analysis focused on specific wavelengths: 280 nm (UV-B), 320 nm, 340 nm, 360 nm (UV-A), 380 nm, and 400 nm.
- Data from a UV-1 model spectrophotometer (Thermo Electron Corporation, USA) was analyzed.
Main Results:
- 75% of lenses failed to meet the US FDA's 95% protection recommendation for UV-A at 360 nm.
- 35% of lenses did not provide the recommended 99% protection against UV-B at 280 nm.
- Hard resin lenses exhibited greater variability in UV-A protection compared to glass lenses.
Conclusions:
- A significant portion of studied lenses do not meet US FDA standards for UV-A protection.
- Glass lenses demonstrated superior UV protection up to 320 nm compared to hard resin lenses.
- Introduction of UVR protection certification for lenses in India is recommended due to manufacturers' claims falling short of international standards.