SELECTED OPHTHALMIC PARAMETERS AND POTENTIAL RISK FOR LIGHT-INDUCED CATARACTS IN TWO COLONIES OF CAPTIVE INDIAN FLYING FOXES (PTEROPUS GIGANTEUS)

Abstract

Indian flying foxes ( Pteropus giganteus) are adapted to visual foraging in dim light. Nine Indian flying foxes were taken from a captive colony of 25 animals and placed in quarantine, off exhibit, in preparation for shipment to another institution. The exhibit had indirect, natural sunlight and was large enough to allow for flight. The quarantine enclosure was subject to >12 hr/day artificial lighting and did not allow for flight or gliding. Diet was identical between groups. After 13 mo, ophthalmic examination was performed on each animal including evaluation of the anterior chamber, rebound tonometry in upright and hanging positions, measurement of palpebral fissure length, and vertical and horizontal corneal diameters. Bilateral cataracts were observed in 55% (5/9) of the quarantined animals but in none of the animals that remained on exhibit (0/16). Bats housed in the quarantine enclosure had a risk of having cataracts 18 times greater than did bats in the exhibit enclosure (relative risk [RR]: 18.70; 95% confidence interval [CI]: 1.15-303.77). There was no association between cataract presence and age (odds ratio [OR]: 0.99; 95% CI: 0.97-1.02; P = 0.7) or sex (OR: 1.24; 95% CI: 0.17-9.25), but lower body weight was associated with presence of cataracts (OR: 0.98; 95% CI: 0.96-0.99). Other ophthalmic parameters observed were similar to those previously reported for other captive Megachiroptera. This study suggests that chronic exposure to artificial lighting predisposes fruit bats to developing light-induced cataracts.

Retrospective analysis of ocular disease in a population of captive pteropodid bats, 2003–2020

“…Toxicity is less likely in this population due to the controlled environment in which they were housed. A previous report of cataracts in a group of Indian flying foxes ( Pteropus giganteus) found that exposure to fluorescent light predisposed the bats to developing cataracts 14 . The bats in the current study were housed in well‐shaded outdoor enclosures with only natural light exposure and had 24‐h access to night houses.…”

“…A previous report of cataracts in a group of Indian flying foxes (Pteropus giganteus) found that exposure to fluorescent light predisposed the bats to developing cataracts. 14 The bats in the current study were housed in well-shaded outdoor enclosures with only natural light exposure and had 24-h access to night houses. There was no statistical association between age and cataract formation, unlike in dogs and humans.…”

“…In addition, 83% of the bats had iris‐iris persistent pupillary membranes, which appeared to be a normal variation in this population 8 . Other publications include a study examining the possibility of light‐induced cataracts in Indian flying foxes ( Pteropus giganteus) , and a survey of ocular pathology in wild microchiropteran bats in Jalisco and Oaxaca, Mexico, which found trauma was the most common etiology of ocular disease 14,15 …”

“…8 Other publications include a study examining the possibility of light-induced cataracts in Indian flying foxes (Pteropus giganteus), and a survey of ocular pathology in wild microchiropteran bats in Jalisco and Oaxaca, Mexico, which found trauma was the most common etiology of ocular disease. 14,15 The aim of this study was to describe the ocular pathology diagnosed in captive-managed pteropodid bats, with the goal of improving husbandry and medical management of these species.…”