Age- and Race-related Changes in Peripapillary and Mid-peripheral Scleral Thickness in Human Donor Eyes

Abstract

 

Purpose

 

To investigate peripapillary scleral thickness changes with age in normal human eyes from donors of European (ED) and African (AD) descent.

 

Methods

 

Twenty-nine pairs of posterior scleral shells from human donors (10 AD, 19 ED; age: 20-90 years) were pressurized at 10 mmHg with PBS. Scleral thickness was first acquired using ultrasound (PacScan 300P) at 20 discrete points in the peripapillary and mid-peripheral regions. The PBS was then replaced by 5% glutaraldehyde at 10 mmHg for 1 hr. In a subsample of 25 eyes (9 ED pairs, 6 AD pairs + 1 eye), the outer and inner surfaces of the sclera were reconstructed using a tactile scanner (Roland Modela MDX-20), and scleral thickness mapped. Scleral thickness changes with age and race were estimated using multivariate linear regression.

 

Results

 

Sclera was significantly thicker in the peripapillary region compared to the mid-peripheral region in both the ED (172 μm, p<0.001) and AD groups (50 μm, p<0.05). For both regions combined (Figure), scleral thickness significantly increased with age in the ED group (2.105 μm/year, p=0.01), while an opposite trend of thinning with age was observed in the AD group (-2.436 μm/year, p=0.01). Overall, the scleral thickness at 90 years in the AD group was estimated to be 205 μm thinner than the ED group (Figure; p<0.001). In the subsample of eyes of ED eyes measured with the tactile scanner, the peripapillary sclera was thicker than mid-peripheral sclera (71 μm, p<0.001), and the thickness significantly increased with age (1.915 μm/year, p=0.015).

 

Conclusions

 

Scleral thickness data measured in the same eyes with two different techniques showed similar trends: 1) peripapillary sclera was thicker than in the mid-periphery; 2) scleral thickness significantly increased with age in the ED group; 3) overall scleral thickness at 90 years old was estimated to be 205 µm thinner in the AD group compared to the ED group (ultrasound data only).

 

 

(Top, Ultrasound data): Average scleral thickness plotted at for the AD group (red; mean and 95% CI) in the ED eyes (blue; mean and 95% CI). Sclera significantly thickened with age in the ED group, but significantly thinned with age in the AD group. (Bottom, Tactile Scanner data): Significant scleral thickening with age (p=0.015) was confirmed in a subsample of eyes from the ED group, but too few AD eyes were completed to analyze.

 

Keywords: 708 sclera • 413 aging