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Abstract #6316 Published in IGR 3-2
Central corneal thickness, tonometry, and ocular dimensions in glaucoma and ocular hypertension
Singh RP; Goldberg I; Graham SL; Sharma A; Mohsin MJournal of Glaucoma 2001; 10: 206-210
PURPOSE: To assess possible correlations between central corneal thickness, tonometry, and ocular dimensions. PATIENTS AND METHODS: One hundred and seventeen eyes of 117 patients who were not taking any intraocular pressure (IOP)-lowering medications were studied prospectively. Forty-one patients had ocular hypertension; 13 had primary open-angle glaucoma (POAG); and ten had normal-pressure glaucoma (NPG). Twenty-three healthy eyes were also included. Thirty glaucoma suspects (ten patients monitored for possible NPG, and 20 with intermittent ocular hypertension) were included for correlation analysis. Tonometry was performed with Goldmann applanation and pneumotonometry, and central corneal thickness, anterior chamber depth, lens thickness, and axial length, were measured ultrasonically. RESULTS: Central corneal thickness was lowest in eyes with NPG (538 ± 51 μm), highest in eyes with ocular hypertension (570 ± 32 μm), and intermediate and similar in eyes with POAG and healthy eyes (547 ± 34 and 554 ± 32 μm, respectively). These differences were significant (p = 0.028). Goldmann applanation tonometry and central corneal thickness were weakly correlated (r = 0.12, p = 0.205), with a 0.2-mmHg change per 10-μm variation in central corneal thickness. Pneumotonometry measurements were more strongly correlated with central corneal thickness (r = 0.21, p < 0.05). Lens thickness was strongly correlated with age (r = 0.57, p < 0.001). Anterior chamber depth was negatively correlated with lens thickness and age (r = -0.29, p < 0.005 and r = -0.25, p < 0.01). Axial length was correlated with anterior chamber depth and age (r = 0.5, p < 0.001 and r = -0.19, p < 0.05). CONCLUSIONS: Eyes diagnosed as having ocular hypertension have thicker corneas and eyes labelled as having NPG have thinner corneas, when compared with healthy eyes or eyes with POAG. The effect of central corneal thickness on Goldmann applanation tonometry accuracy appears to be small, and usually not clinically relevant. When corneal thickness is markedly different from normal, the clinical may need to factor this into diagnosis and management.
Dr I. Goldberg, Park House, Floor 4, Suite 2, 187 Macquarie Street, Sydney 2000, New South Wales, Australia. ivangoldberg@iname.com
Classification:
2.2 Cornea (Part of: 2 Anatomical structures in glaucoma)
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)
6.12 Ultrasonography and ultrasound biomicroscopy (Part of: 6 Clinical examination methods)
