Lower corneal hysteresis is associated with more rapid glaucomatous visual field progression.
ABSTRACT We investigated the correlation between central corneal thickness (CCT) and corneal hysteresis (CH) and their relationship with the rate of visual field (VF) change.
Glaucoma patients who underwent complete ophthalmic examination and tonometry using both the Goldmann applanation tonometer and the Ocular Response Analyzer were prospectively enrolled. Only eyes with ≥5 SITA Standard 24-2 VF tests were included. Automated pointwise linear regression analysis was used to determine VF progression. One hundred fifty-three eyes (153 patients; mean age, 61.3 ± 14.0 y; mean number of VF, 8.5 ± 3.4; mean follow-up time, 5.3 ± 2.0 y) met the enrollment criteria.
The mean global rate of VF change was -0.34 ± 0.7 dB/y. Twenty-five eyes (16%) reached a progression endpoint. Progressing eyes had lower CCT (525.0 ± 34.2 vs 542.3 ± 3 8.5 μm, P=0.04) and lower CH (7.5 ± 1.4 vs 9.0 ± 1.8 mm Hg, P<0.01) compared with nonprogressing eyes. CH and CCT correlated significantly (r=0.33, P<0.01). By multivariate analysis, peak intraocular pressure [odds ratio (OR)=1.13 per mm Hg higher, P<0.01], age (OR=1.57 per decade older, P=0.03), and CH (OR=1.55 per mm Hg lower, P<0.01) remained statistically significant.
Corneal biomechanical and physical properties, such as CH and CCT, are highly correlated and associated with VF progression. As CH may describe corneal properties more completely than thickness alone, it may be a parameter that is better associated with progression.
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ABSTRACT: To determine whether central corneal thickness (CCT) correlates with measured intraocular pressure (IOP) response to topical ocular hypotensive medication in the Ocular Hypertension Treatment Study (OHTS). Prospective randomized clinical trial. Intraocular pressure measurements were performed by Goldmann applanation tonometry. Central corneal thickness was measured by ultrasonic pachymetry. The following indicators of IOP response to topical ocular hypotensive medication were examined: (1) IOP after an initial four- to six-week one-eyed therapeutic trial of a nonselective beta-blocker (N = 549) or a prostaglandin analog (N = 201); (2) the mean IOP response during 12 to 60 months of follow-up among medication participants (N = 689); (3) the percentage of follow-up visits at which both eyes met the treatment goal; (4). the total number of different medications prescribed to reach treatment goal; and (5) the total number of different medications prescribed multiplied by the number of months each medication was prescribed. Central corneal thickness was inversely related to the IOP response after the initial one-eyed therapeutic trial and during 12 to 60 months of follow-up (P < .05). Mean CCT was not correlated with the number of different medications prescribed during follow-up, the total medication-months, or the percentage of visits at which IOP target was met. Individuals with thicker corneas had smaller measured IOP responses to ocular hypotensive medication than those with normal or thin corneas. We believe that CCT measurements may be useful in patient management and in interpreting clinical trials of ocular hypotensive medication.American Journal of Ophthalmology 11/2004; 138(5):717-22. · 3.63 Impact Factor
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ABSTRACT: We sought to measure the impact of central corneal thickness (CCT), a possible risk factor for glaucoma damage, and corneal hysteresis, a proposed measure of corneal resistance to deformation, on various indicators of glaucoma damage. Observational study. Adult patients of the Wilmer Glaucoma Service underwent measurement of hysteresis on the Reichert Ocular Response Analyzer and measurement of CCT by ultrasonic pachymetry. Two glaucoma specialists (H.A.Q., N.G.C.) reviewed the chart to determine highest known intraocular pressure (IOP), target IOP, diagnosis, years with glaucoma, cup-to-disk ratio (CDR), mean defect (MD), pattern standard deviation (PSD), glaucoma hemifield test (GHT), and presence or absence of visual field progression. Among 230 subjects, the mean age was 65 +/- 14 years, 127 (55%) were female, 161 (70%) were white, and 194 (85%) had a diagnosis of primary open-angle glaucoma (POAG) or suspected POAG. In multivariate generalized estimating equation models, lower corneal hysteresis value (P = .03), but not CCT, was associated with visual field progression. When axial length was included in the model, hysteresis was not a significant risk factor (P = .09). A thinner CCT (P = .02), but not hysteresis, was associated with a higher CDR at the most recent examination. Neither CCT nor hysteresis was associated with MD, PSD, or GHT "outside normal limits." Thinner CCT was associated with the state of glaucoma damage as indicated by CDR. Axial length and corneal hysteresis were associated with progressive field worsening.American Journal of Ophthalmology 06/2006; 141(5):868-75. · 3.63 Impact Factor
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ABSTRACT: The aim of this study is to compare the hysteresis and corneal resistance factor (CRF) in normal tension glaucoma (NTG), primary open angle glaucoma (POAG) and ocular hypertension (OHT) eyes measured by the ocular response analyser (ORA). This is a prospective, cross-sectional and comparative clinical trial. The setting was a teaching hospital in Birmingham, England. 216 eyes with POAG, 68 eyes with NTG and 199 eyes with OHT. Observational procedures: Goldmann applanation tonometry and intraocular pressure (IOP), hysteresis and CRF measured by ORA and central corneal thickness (CCT) by ultrasonic pachymetery. The main outcome measures were IOP, CCT, hysteresis and CRF. The hysteresis in NTG, POAG and OHT eyes was 9.0 +/- 1.9, 9.9 +/- 2.1 and 10.2 +/- 2.0 mmHg; CRF was 9.1 +/- 2.2, 10.6 +/- 2.0 and 12.0 +/- 2.0 mmHg; IOP by Goldmann applanation tonometry and ORA was 14.7 +/- 2.8 and 15.3 +/- 4.2 mmHg, 16.7 +/- 4.0 and 16.9 +/- 4.6 mmHg and 20.5 +/- 4.1 and 20.0 +/- 4.5 mmHg; CCT was 526.5 +/- 42.2, 537.0 +/- 36.0 and 563.4 +/- 35.9 microm, respectively. The difference for CRF, IOP and CCT for NTG, POAG and OHT eyes was statistically significant. Hysteresis and CRF were highest in OHT eyes. These factors may prove to be useful measurements of ocular rigidity and may help to understand role of the corneal rigidity in monitoring the progress of conditions such as NTG, POAG and OHT.Clinical and Experimental Ophthalmology 09/2008; 36(6):508-13. · 1.96 Impact Factor