Unexpected Retinal Abnormalities in the Cone-Dominant Northern Tree Shrew

Area of Science:

• Ophthalmology
• Comparative Medicine
• Animal Models

Background:

• Tree shrews possess cone-dominant vision similar to primates, making them valuable for vision research.
• Established noninvasive imaging techniques (SLO, OCT, ASO) allow detailed retinal analysis in tree shrews.
• Previous studies utilized tree shrews for myopia, glaucoma, and diabetic retinopathy models.

Purpose of the Study:

• To characterize novel retinal abnormalities in a cohort of presumed normal tree shrews.
• To document distinct retinal phenotypes observed via noninvasive imaging.
• To emphasize the importance of identifying the etiology of these findings for future research.

Main Methods:

• Noninvasive retinal imaging was performed on 31 presumed normal tree shrews.
• Retinal structure and autofluorescence were assessed using techniques like scanning laser ophthalmoscopy and optical coherence tomography.
• Observed retinal findings were categorized into distinct phenotypes.

Main Results:

• Fifteen out of 31 tree shrews exhibited one of three distinct retinal phenotypes.
• Phenotype 1 (n=10): hypo-reflective/hypo-autofluorescent foci nasal to the optic nerve.
• Phenotype 2 (n=4): mottled fundus with outer retinal disruption temporal to the optic nerve.
• Phenotype 3 (n=1): decreased reflectance/autofluorescence with inner retinal thinning and cone mosaic disruption.

Conclusions:

• A significant proportion of presumed normal tree shrews present with distinct retinal abnormalities.
• These findings necessitate further investigation, including genetic testing and histology, to determine the cause.
• Understanding these phenotypes is crucial for the accurate use of tree shrews in vision research.