Otago glaucoma surgery outcome study: tissue matrix breakdown by apoptotic cells in capsules surrounding molteno implants.
OBJECTIVE
To identify cell types and extracellular matrix components in Molteno implant capsules.


METHODS
Histologic features including cytology, distribution of apoptotic cells, cytoantigens, collagens, basement membranes, elastic fibers, and glycoproteins were examined by light microscopy. Findings were correlated with the clinical features of 19 ocular specimens with glaucoma that had been treated with Molteno implants 11 days to 20 years previously.


RESULTS
All but the earliest specimen capsules showed two layers: a moderately cellular outer layer of normally stained collagen and an inner avascular hypocellular layer of altered collagen. Capsules contained metabolically active fibroblasts and macrophages showing swelling, vacuolation, and apoptosis with localized loss of extracellular matrix in the inner layers of older capsules. Type I collagen was present in trace amounts. Collagens types III and VI and fibronectin were present in high concentrations in the capsules. Basement membrane material (collagen type IV and laminin) and thrombospondin were concentrated in the inner avascular layers.


CONCLUSIONS
These results support previous findings that the normal capsule life cycle includes continual inner surface degeneration and external surface renewal. The cells and tissue matrix components of the outer capsule layer matched those involved in the initial phase of wound healing in vascular connective tissue. The tissue matrix components and widespread apoptosis found in the inner fibrodegenerative layer reflect scar tissue remodelling induced by exposure to the aqueous.
Molteno
Anthony C B
AC
Ophthalmology Section, Medical and Surgical Sciences, University of Otago, Dunedin School of Medicine, Dunedin, New Zealand.
Thompson
Andrew M
AM
Bevin
Tui H
TH
Dempster
Alex G
AG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D001485:Basement Membrane / Q000378:metabolism / Q000473:pathology; D003238:Connective Tissue / Q000378:metabolism / Q000473:pathology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D015353:Eye Enucleation; D005260:Female; D005347:Fibroblasts / Q000473:pathology*; D005901:Glaucoma / Q000601:surgery*; D006801:Humans; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D008264:Macrophages / Q000473:pathology*; D008297:Male; D018465:Molteno Implants; D014617:Vacuoles
D016326:Extracellular Matrix Proteins