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PURPOSE: To measure oxygen (pO2) in eyes of patients undergoing intraocular surgery and identify correlations with central corneal thickness (CCT). DESIGN: Prospective, cross-sectional study METHODS: Setting: Institutional. Patient Population: 124 patients undergoing cataract and/or glaucoma surgery. Observation Procedure: Prior to surgery, an oxygen sensor was introduced into the anterior chamber (AC) via peripheral corneal paracentesis. The tip of the flexible fiberoptic probe was positioned for three measurements in all patients: (1) near central corneal endothelium, (2) in mid-AC and (3) in AC angle. In patients undergoing cataract extraction, additional measurements were taken (4) at the anterior lens surface and (5) in the posterior chamber. MAIN OUTCOME MEASURES: pO2 measurements at five locations within the eye were compared to central corneal thickness measurements by multivariate regression analyses. RESULTS: There was a statistically significant inverse correlation between CCT and pO2 in the anterior chamber angle (p=0.048). pO2 was not significantly related to CCT at any other location, including beneath the central cornea. Regression analysis relating CCT to age, race and oxygen levels in all five locations in the anterior segment revealed an association of a thinner cornea with increasing age (p=0.007). CONCLUSIONS: Physiologic correlations with central corneal thickness may provide clues to understanding why a thinner cornea increases the risk of open glaucoma. Associations between glaucoma risk, CCT and pO2 in the AC angle suggest that exposure of the outflow system to increased oxygen or oxygen metabolites may increase oxidative damage to the trabecular meshwork cells, resulting in elevation of intraocular pressure.
Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO, USA. Electronic address: siegfried@vision.wustl.edu.
Full article2.2 Cornea (Part of: 2 Anatomical structures in glaucoma)
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
2.6.3 Compostion (Part of: 2 Anatomical structures in glaucoma > 2.6 Aqueous humor dynamics)
3.9 Pathophysiology (Part of: 3 Laboratory methods)