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The relationship between pore density and outflow facility in human eyes
R R Allingham1, A W de Kater, C R Ethier
1Howe Laboratory of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston.
Investigative Ophthalmology & Visual Science
|April 1, 1992
Summary
Primary open angle glaucoma (POAG) eyes show fewer pores in Schlemm's canal endothelium, impacting outflow facility. This suggests intrinsic endothelial differences in POAG, though not fully explaining reduced facility.
Area of Science:
- Ocular Physiology
- Glaucoma Research
- Endothelial Cell Biology
Background:
- Schlemm's canal inner wall (IW) endothelium regulates aqueous humor outflow.
- Primary open angle glaucoma (POAG) is characterized by impaired aqueous humor outflow.
- Understanding IW endothelial function is crucial for glaucoma pathogenesis.
Purpose of the Study:
- To compare IW endothelial morphology and function in normal and POAG human eyes.
- To investigate the relationship between IW endothelial pore characteristics and outflow facility.
- To determine the contribution of IW endothelium to total outflow resistance in POAG.
Main Methods:
- Scanning electron microscopy of IW endothelium from normal and POAG human eyes.
- Constant pressure perfusion to measure outflow facility at 15 mmHg.
- Quantification of IW endothelial pore density, diameter, and bulge density.
- Calculation of IW endothelial facility, resistance, and hydraulic conductivity.
Main Results:
- POAG eyes exhibited significantly lower IW endothelial pore density (489 pores/mm²) compared to normal eyes (1437 pores/mm²).
- IW endothelial pore density strongly correlated with measured outflow facility in both normal and POAG eyes.
- The IW endothelium contributed a higher percentage of total resistance in POAG eyes (9.5%) versus normal eyes (5.8%).
Conclusions:
- A reduced and potentially unevenly distributed pore structure in the IW endothelium of POAG eyes.
- Intrinsic differences in IW endothelial function exist between normal and glaucomatous eyes.
- While IW endothelial dysfunction contributes to POAG, it doesn't solely account for the decreased outflow facility.