Posterior scleral thickness in perfusion-fixed normal and early-glaucoma monkey eyes

Area of Science:

• Ophthalmology
• Biomechanics
• Histology

Background:

• The posterior sclera's structural integrity is crucial for maintaining ocular shape and function.
• Understanding regional variations in scleral thickness is essential for glaucoma research.
• Intraocular pressure (IOP) is a key risk factor for glaucoma progression.

Purpose of the Study:

• To map posterior scleral thickness in normal monkey eyes.
• To investigate the impact of acute and short-term chronic elevated IOP on scleral thickness.
• To assess how IOP changes affect regional scleral biomechanics.

Main Methods:

• Histomorphometric analysis of posterior scleral thickness at 15 points per eye.
• Measurement in normal monkey eyes and eyes with induced chronic IOP elevation.
• Grouping data by anatomical region: foveal, midposterior, posterior-equatorial, and equatorial.

Main Results:

• Significant regional differences in posterior scleral thickness were observed (P < 0.0001).
• The foveal region exhibited the greatest thickness (307 µm), with progressive thinning towards the equator.
• Elevated IOP (30-45 mm Hg) resulted in overall and regional posterior scleral thinning compared to normal IOP eyes.

Conclusions:

• The normal monkey posterior sclera thins from the fovea to the equator, being thinnest posterior to the equator.
• Acute and short-term chronic IOP elevations induce regional thinning in the posterior sclera.
• This IOP-induced thinning significantly elevates stress within the scleral wall, potentially contributing to glaucoma pathogenesis.