Ultrastructural changes in the trabecular meshwork of juvenile glaucoma

Area of Science:

• Ophthalmology
• Cell Biology
• Pathology

Background:

• Juvenile glaucoma is a severe form of glaucoma requiring early intervention.
• The trabecular meshwork (TM) plays a crucial role in regulating intraocular pressure (IOP).
• Abnormal extracellular matrix accumulation in the TM is implicated in various glaucoma types.

Purpose of the Study:

• To investigate the ultrastructural and quantitative changes in the trabecular meshwork of patients with juvenile glaucoma.
• To characterize the nature and distribution of extracellular material in juvenile glaucoma.
• To compare findings in juvenile glaucoma with those in steroid-induced glaucoma and primary open-angle glaucoma.

Main Methods:

• Electron microscopy of trabeculectomy specimens from 11 juvenile glaucoma patients.
• Quantitative evaluation of extracellular material and cellular changes within the trabecular meshwork.
• Comparison with known pathological features of other glaucoma types.

Main Results:

• Consistent presence of abundant extracellular material with a fingerprint-like pattern, identified as basement-membrane-like material (FBM), in all specimens.
• FBM was primarily located in the inner cribriform and outer corneoscleral regions, leading to significant thickening of the cribriform layer.
• Activated trabecular cells were frequently observed in association with FBM. Increased fine fibrillar material and sheath-derived plaque material were also noted in some cases.

Conclusions:

• Juvenile glaucoma is characterized by significant accumulation of FBM within the trabecular meshwork, contributing to TM dysfunction.
• The ultrastructural findings in juvenile glaucoma share similarities with steroid-induced glaucoma, suggesting common pathogenic mechanisms.
• These TM alterations likely impede aqueous humor outflow, contributing to elevated IOP in juvenile glaucoma.