Indian Journal of Ophthalmology

ARTICLES
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

Correspondence Address:
B K Kharmar
M. And J. Institute ofOphthalmology.Civil Hospitals, Ahmedabad
India




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 2021 Sep 17 ];31:842-843
Available from: https://www.ijo.in/text.asp?1983/31/7/842/29682


Full Text

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.[1]

In the last few years various other evidences have been accumulated to suggested that sun­

light can also produce cataracts[1],[3],[4].

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[5]. 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.[6] It is also known to cause cataracts on long term exposures with­out increasing the temperature.[7]

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.

References

1Khamar B.M., Rawal U.M. Ghodadra B.K. 1981 Presented to 9th Guj. Ophth. Conference Ahmedabad.
2Rita Hiller, Luigi Giacometti and Karen Yuen. 1977. Vol. 105 No.5, 450-459.
3Hugh R. Taylor, 1980. Ophthalmol. 64: 303-310.
4Zigman S, 1979. Invest Ophtholmol. 18: 463.
5Sidney Lerman, 1980. Radiant energy and the eye. Vol. 1. P.146, Functional Ophthalmology series.
6Langely R.K., Motimer C.B. and Mc Cullo H.C. 1960. Arch. Ophtholmol 63 : 473 - 88.
7Wolbarsht M. L., Yamanashi, B. S. and Orr M. A. 1976. Ann. Prog. Report U.S Army Med. Res. Dev. Command.