Effect of intermittent light on photoreceptor cells in the rabbit retina.
OBJECTIVE
The objective of the present study was to determine what histological changes occur in the photoreceptor layer of male rabbits exposed to intermittent light of different intensities.


METHODS
Twelve adult male rabbits were randomly divided into three groups: control group (CON), experimental group I (EXP-1), and experimental group II (EXP-2). The EXP-1 and EXP-2 groups were exposed to a 3-h/3-h light-dark cycle, with light provided by a 60-W or 200-W fluorescent bulb, respectively. The eyes of the rabbits were removed, routinely fixed, and studied by transmission electron microscopy.


RESULTS
The EXP-1 rabbits showed the least photoreceptor damage, such as only slight vacuolization in the inner segment, but normal appearance in the other layers. The EXP-2 rabbits showed disorganization and distention in the outer segments and sublethal injury in the inner segment, such as vacuolization, mitochondrial distention and disorganization, increased extracellular space, and distention of cisternae in the rough endoplasmic reticulum. In the EXP-2 group, the outer limiting membrane was absent at some sites, and swelling and pyknosis were present.


CONCLUSIONS
These observations suggest that intermittent high-intensity light causes more damage in the photoreceptor layer of the rabbit than does intermittent low-intensity light.
Esfandiari
Arash
A
Department of Anatomical Sciences, School of Veterinary Medicine, Islamic Azad University, Kazerun Branch, Kazerun, Iran. esfandiari.arash@gmail.com.|Department of Anatomical Sciences, School of Veterinary Medicine, Islamic Azad University, Kazerun Branch, P.O. Box 73135-168, Kazerun, 73198-66451, Iran. esfandiari.arash@gmail.com.
Yousofi
Alireza
A
Department of Pathological Sciences, School of Veterinary Medicine, Islamic Azad University, Kazerun Branch, Kazerun, Iran.
Dehghan
Asghar
A
Department of Clinical Sciences, School of Veterinary Medicine, Islamic Azad University, Kazerun Branch, Kazerun, Iran.
Safavi
Ali
A
Department of Electron Microscopy, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
D000818:Animals; D008027:Light; D008297:Male; D020419:Photoreceptor Cells, Vertebrate / Q000528:radiation effects* / Q000648:ultrastructure; D011817:Rabbits; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000209:etiology* / Q000473:pathology; D012162:Retinal Degeneration / Q000209:etiology* / Q000473:pathology; D013997:Time Factors