Article
Normal Transmission of the Human Lens with Age: Relationship to Intraocular Lenses with Ultraviolet, Blue, or No Light Blocking Filters
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Authors
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J. T. Holladay
- LASIK Institute, Baylor College of Medicine, Houston/USA
| Published: | September 22, 2004 |
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Outline
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Objective
To determine the average transmission of the human crystalline lens as a function of age, compare it to intraocular lenses with various transmission curves (blue filtering, UV-blocking, non-UV blocking) and relate these transmission curves to risk factors for retinal damage and sacrifices in visual function.
Methods
Absorbance data (24 normal eyes from 0 to 80-years-old) from Weale, transmission data from Boetner (9 normal eyes from 1 month to 92-years-old) and Peters (2 neonates) were analyzed to determine the normal transmission of the human lens as a function of age. Mean transmission curves for age 0, 20, 50, 70 & 90-years-old were then generated. These data were then compared with the transmission data from blue filtering (3 IOLs), UV-blocking (generic) and non-UV blocking (generic) lenses to determine the differences from 300 to 900 nanometers. The IOL transmission curves and age-dependent crystalline lens transmission curves were convolved with standard daylight light source (K° = 5500) so that the IOLs could be equated to the normal crystalline lens at a specific age. The effect on color vision for each IOL was then determined from age-related normative data using the Farnsworth-Munsell 100 and the Anomoloscope.
Results
The non-UV IOLs transmit wavelengths as low as 320 nanometers, which is much more UV and blue light than the neonate. The UV-blocking IOLs cut-off UV similar to the neonate, but allow substantially more blue, yellow and green light. The blue-filtering IOLs were similar to the 50-year-old crystalline lens for UV and blue light, but allow significantly more yellow and green light than even the neonate. Color vision is best at age 19 and decreases almost linearly with age. Current blue-filtering IOLs will produce a significant loss in the blue wavelengths as documented by the Farnsworth-Munsel 100 and Anomoloscope testing.
Conclusions
Non-UV and UV-blocking IOLs have an exaggeration of blue colors and blue filtering IOLs have blue color vision loss similar to the 50-year-old crystalline lens or slightly worse due to the exaggeration of yellow and green. The human color vision discrimination is at 19 years of age and considering the risks and benefits of UV and blue light is the optimal transmission of the pseudophakic IOL.
