Naturally occurring strabismus in monkeys (Macaca nemestrina)

Area of Science:

• Ophthalmology
• Primatology
• Neuroscience

Background:

• Strabismus, or squint, is a common visual disorder.
• Animal models are crucial for understanding complex visual conditions like strabismus and amblyopia.
• Naturally occurring cases in non-human primates are rare but highly informative.

Purpose of the Study:

• To identify and characterize naturally occurring strabismus in Macaca nemestrina (pigtail macaques).
• To investigate potential causes and functional visual deficits associated with strabismus in these animals.
• To evaluate the suitability of macaques as a model for strabismus and amblyopia research.

Main Methods:

• Identification of seven naturally strabismic pigtail macaques.
• Ophthalmoscopic examination of five affected monkeys.
• Behavioral testing of visual responsiveness and visual acuity in two monkeys.

Main Results:

• No obvious ophthalmoscopic cause for strabismus was found in any examined monkey.
• Monkeys exhibited poorer-than-normal visual acuity in both eyes.
• Amblyopia, a reduction in best corrected visual acuity, was quantified (0.6-0.8 octaves).

Conclusions:

• The presence of naturally strabismic macaques provides a valuable resource.
• These animals demonstrate functional visual deficits analogous to human strabismus and amblyopia.
• Macaca nemestrina is a suitable animal model for investigating the mechanisms and potential treatments of strabismus and amblyopia.