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J.S. Weizer, S.S. Stinnett, L.W. Herndon; The Clinical Utility of Dynamic Contour Tonometry and Ocular Pulse Amplitude . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4797.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if dynamic contour tonometry (DCT IOP) is affected by central corneal thickness (CCT), and if ocular pulse amplitude as measured by dynamic contour tonometry (DCT OPA) is related to glaucoma severity.
Patients were randomly and prospectively selected from the Duke Eye Center glaucoma clinic. Diagnoses were: normal, ocular hypertension (OHT), glaucoma suspect, or primary open angle glaucoma (POAG). Exclusion criteria were: secondary glaucoma, recent contact lens wear, recent eye surgery, or any previous corneal surgery. Diagnosis and previous glaucoma incisional surgery were recorded per eye. Examination included: visual acuity, spherical equivalent, keratometry, pachymetry, Goldmann applanation tonometry (GAT), Tonopen applanation tonometry (TAT), DCT IOP, DCT OPA, vertical and horizontal cup/disc ratios, and systemic blood pressure. For POAG patients, Humphrey visual fields were analyzed for Advanced Glaucoma Intervention Study (AGIS) score and mean deviation of visual field. Descriptive statistics were obtained, and GAT, TAT, DCT IOP, and DCT OPA underwent univariable analyses to assess relationships with predictor variables (age, spherical equivalent, keratometry, pachymetry, systemic blood pressure, AGIS score, mean deviation of visual field, and vertical and horizontal cup/disc ratios).
Fifty–five eyes of 32 patients were included. Thirty–seven eyes had POAG, 8 had normal tension glaucoma, 4 were glaucoma suspects, 4 had OHT, and 2 were normal. Mean GAT was 15.1 mmHg for right eyes and 13.8 mmHg for left eyes. Mean TAT was 12.1 for right eyes and 11.2 for left eyes. Mean DCT IOP was 17.6 for right eyes and 15.4 for left eyes. These mean differences between measuring methods were statistically significant (p<0.001). Statistically significant relationships included: increased mean GAT, TAT, and DCT IOP correlated with having no history of previous incisional glaucoma surgery (p<0.02), increased mean CCT (p<0.03), and smaller mean vertical and horizontal cup/disc ratios (p<0.05). Increased mean DCT OPA correlated with having no previous incisional glaucoma surgery (p=0.02), increased mean deviation of visual field (p=0.02), decreased mean AGIS score (p=0.05), increased mean CCT (p=0.01), and smaller mean vertical and horizontal cup/disc ratios (p=0.05).
DCT IOP appears to be affected by CCT along with GAT and TAT. Increased DCT OPA appears to correlate with less visual field damage, thicker corneas, and smaller cup/disc ratios. Measuring OPA may be useful in assessing glaucoma severity.
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