الفهرس 
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Abstract
Atmospheric changes such as depletion of ozone layer in the
stratosphere are believed to lead to rises the level of ultraviolet
radiation on the earth. In general, there are a number of body
components that absorb ultraviolet radiation and may induce
photochemical damage to the tissue. The most common are
chromophores, nucleic acid and proteins including various types of
enzymes. All these factors lead to opacity of the normal crystallin
lens that produces an impairment of vision and associated with
cataract formation.
This study aimed to investigate the damaging effect of total and
fractionated doses of ultraviolet B (UVB) radiation on the eye lens
and the effect of melatonin against oxidative stress in UVB radiationinduced
cataract development.
Twenty-five New Zealand male rabbits weighing 1.5-2 kg were
used in this study and divided into five groups (five rabbits each).
Group I. Rabbits kept as control without any treatment.
Group II. Rabbits received a total dose of 3.12 J/cm2 UVB and
they were left for one week.
Group III. Rabbits injected intraperitoneal with melatonin
(4mg/kg) daily for one week before exposure then they
received a total dose of 3.12 J/cm2 UVB and following the
exposure they again injected intraperitoneal with melatonin
daily for one week.