Year : 1983 | Volume
: 31 | Issue : 7 | Page : 842--843
Sunlight-its etiological role in cataract formation
BK Kharmar, UM Rawal
M and J, Institute of Ophthalmology, Civil Hospitals, Ahmedabad and Department of Zoologgy, University School of Sciences, Gujarat University, Ahmedabad, India
B K Kharmar
M. And J. Institute ofOphthalmology.Civil Hospitals, Ahmedabad
|How to cite this article:|
Kharmar B K, Rawal U M. Sunlight-its etiological role in cataract formation.Indian J Ophthalmol 1983;31:842-843
|How to cite this URL:|
Kharmar B K, Rawal U M. Sunlight-its etiological role in cataract formation. Indian J Ophthalmol [serial online] 1983 [cited 2022 Aug 8 ];31:842-843
Available from: https://www.ijo.in/text.asp?1983/31/7/842/29682
Cataract is a major cause of blindness and visual impairment in our country. There has been various postulations for the etiology of cataract. The main factor which is blamed for cataractogenesis is the process of ageing. This is not true for our country. Cataracts occur at relatively younger age in large number without demonstrating any other senile changes.
In the last few years various other evidences have been accumulated to suggested that sun
light can also produce cataracts,,.
Sunlight is composed mainly of ultraviolet rays, visible spectrum and infrared rays. Of these ultraviolet light has been used for experimental studies on cataractogenesis in various experiments. Various investigations have shown that ultraviolet light can cause cataracts in experimental animal in vivo as well as in vitro where as in human lenses in vitro condition. Infrared light is also known to produce cataracts in experimental animals in vivo because of its thermal effect. It is also known to cause cataracts on long term exposures without increasing the temperature.
Solar energy is usually measured in terms of available sunshine e.g. sunshine hours, ultraviolet radation, average temperature per annum, direct solar radation, global solar radation, etc.
To know its effect the sunlight data were obtained from two places U.S.A. and Ahmedabad which have different solar energy.
OBSERVATIONS & DISCUSSION
[Table 1] shows that in Ahmedabad cataracts are removed at an early age compared to U.S.A.
[Table 2] shows that Ahmedabad receives 2-3 times more solar energy than U.S.A.U.V. radiation is also more in Ahmedabad 375mm compared to 275mm (average for U.SA.). Average temperature per annum is 27.8° C in Ahmedabad compared to 13° to 18° C in U.S.A.
These two tables suggest that sunlight is received more in Ahmedabad compared to U.S.A. and cataracts also occur at relatively younger age group in Ahmedabad.
U.S.A. is large country and data varies from one place to another and so datas were collected from Ahmedabad and Madras situated at different lattitudes.
[Table 3] gives age at cataract extraction at these two places. It was found that the data is more or less identical. [Table 4] gives data about sunlight at two places.
Data regarding solar energy suggests that they are identical at these two places in India in many respects except direct solar radiation and sunshine hours.
Ahmedabad has more sunshine hours compared to Madras. But this is of no significance because solar energy depends on many factors besides sunshine hours e.g. distance from equator.
In the same way direct solar radation is of least significance b--cause 1) persons are exposed more to global solar radiation than direct solar radation.
2) adaptation is very fast and nullifies the effect of direct solar radation.
This shows identical prevalence of cataracts at two different places situated away from each other but with identical solar energy and lower incidences where solar energy is also low.
These facts in combination with experimental evidences are a strong support in favour of sunlight as a major cause. of cataract ogenesis.
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