Physiologic intereye differences in monkey optic nerve head architecture and their relation to changes in early...

Area of Science:

• Ophthalmology
• Comparative Anatomy
• Glaucoma Research

Background:

• Optic nerve head (ONH) architecture exhibits physiologic intereye differences (PIDs) that can influence glaucoma diagnosis.
• Understanding normal PIDs is crucial for detecting subtle pathological changes in experimental glaucoma models.

Purpose of the Study:

• To quantify PIDs in ONH structural parameters in normal rhesus monkeys.
• To compare these normal PIDs with intereye differences observed in early experimental glaucoma (EEG) cynomolgus monkeys.

Main Methods:

• Serial sectioning, 3D reconstruction, and parameterization of ONH and peripapillary sclera from normal rhesus monkeys.
• Calculation of PIDs and physiologic intereye percent differences (PIPDs) for various ONH parameters.
• Comparison of intereye differences in EEG monkeys against established PID and PIPD maximums from normal animals.

Main Results:

• Normal PIDs for ONH parameters were generally small.
• EEG monkeys exhibited greater intereye differences in laminar deformation, posterior scleral canal enlargement, cupping, and prelaminar neural tissue thickening compared to normal PID maximums.
• Regional analysis revealed specific locations of lamina cribrosa deformation and prelaminar neural tissue thickening in EEG eyes.

Conclusions:

• This study provides the first characterization of PID and PIPD maximums for ONH neural and connective tissues in normal monkeys.
• The findings help delineate early ONH changes in experimental glaucoma.
• Further studies are recommended in rhesus monkeys to confirm findings due to species differences.