Advice
Clinical and technical evidence
Clinical and technical evidence
A literature search was carried out for this briefing in accordance with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting mibs@nice.org.uk.
Published evidence
This briefing summarises 5 studies; 4 done in the US and 1 done in Korea, including a total of 635 adults with glaucoma (822 eyes). Three were prospective cohort studies (n=400) and 2 were retrospective studies (n=235).
Table 3 summarises the clinical evidence as well as its strengths and limitations.
Overall assessment of the evidence
The results of all 5 studies suggest that corneal hysteresis is associated with the development and progression of glaucoma. Three studies also showed correlations between corneal hysteresis and corneal central thickness, and 2 studies showed correlations between corneal hysteresis and intraocular pressure.
None of the studies was conducted in the UK so the results may not be generalisable to the NHS.
The company claims that ORA G3 will benefit people with suspected glaucoma, as well as people with a confirmed diagnosis of glaucoma. However, only 1 of the studies (n=199) included people with suspected glaucoma.
Prospective, controlled, UK studies that assess the value of measuring corneal hysteresis alongside standard of care would be useful.
Table 3 Summary of selected studies
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Study size, design and location |
A prospective observational cohort study of 199 adults (287 eyes) with suspected glaucoma in the US. |
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Key parameters of interest |
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Key outcomes |
CH measurements at baseline were significantly lower in people who developed glaucoma compared with those that did not (9.5±1.5 vs 10.2±2.0 mmHg, p=0.012). Each 1 mmHg lower CH was associated with a 22% increase in the risk of developing glaucoma during follow-up (HR=1.22, 95% CI 1.04 to 1.41, p=0.013). In multivariable analysis, adjusted for age, IOP, CTT and PSD, CH was still predictive of glaucoma (HR=1.20, 95% CI 1.01 to 1.42, p=0.039). |
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Strengths and limitations |
The study recruited a relatively large group of people but in a non-UK setting. Adults with suspected glaucoma were included. The patient population in other studies are people with established glaucoma. |
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Study size, design and location |
A retrospective study of 153 adults with glaucoma (153 eyes) in the US. |
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Key parameters of interest |
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Key outcomes |
Eyes that had VF progression had lower CH compared with non-progressing eyes (7.5±1.4 vs 9.0±1.8 mmHg). There was a moderate and significant correlation between CH and CCT (r=0.33, p<0.01). In multivariate analysis, CH was the corneal parameter most strongly associated with VF progression (OR 1.55, CI 1.14 to 2.10, p<0.01). |
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Strengths and limitations |
The study recruited a relatively large number of adults but in a non-UK setting. |
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Study size, design and location |
A prospective observational cohort study of 133 adults with glaucoma (186 eyes) at a glaucoma centre in the US. |
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Key parameters of interest |
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Key outcomes |
In univariate analysis, each 1 mmHg lower CH was associated with a 0.13 micrometre per year faster rate of RNFL loss (p=0.011). In multivariable analysis adjusting for age, race, average GAT IOP and CTT, CH was still associated with a faster rate of RNFL loss (p=0.015). CCT was not found to be associated with RNFL loss. |
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Strengths and limitations |
The study recruited a relatively large number of people. A limitation of the study is that treatment was decided by the attending ophthalmologist and not standardised. Different treatment options may have influenced progression rates. |
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Study size, design and location |
An observational cohort study of 68 adults with glaucoma (114 eyes) at a glaucoma centre in the US. |
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Key parameters of interest |
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Key outcomes |
In univariable analysis, each 1 mmHg lower CH was associated with 0.25% per year faster rate of VF decline over time (p<0.001). In multivariable analysis the authors concluded that there were a significant interaction between IOP and CH. There was a relationship between CCT and CH (r=0.48, p<0.001). |
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Strengths and limitations |
A relatively small number of adults was recruited into the study. |
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Study size, design and location |
A retrospective cross-sectional observational study of 82 adults with NTG (82 eyes) at a glaucoma clinic in Seoul, Korea. |
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Key parameters of interest |
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Key outcomes |
26 of 39 eyes with low CH had progression of VF damage compared with 15 of 43 eyes with high CH (p<0.01). In univariate and multivariable regression analysis CH was significantly correlated with VF progression (univariate beta=0.39, p<0.01, multivariable beta=0.32; p=0.01). CH had a moderate and significant correlation with CCT (r=0.44, p<0.01) and IOPcc (r=−0.52, p<0.01). |
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Strengths and limitations |
Study participants were having anti-glaucoma medications. CH may have been increased by IOP-lowering therapy. A relatively small number of adults were recruited into the study. |
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Abbreviations: CCT, central corneal thickness; CH, corneal hysteresis; CRF, corneal resistance factor; IOP, intraocular pressure; IOPcc, corneal compensated intraocular pressure; IOPg, Goldmann estimated intraocular pressure; PSD, pattern standard deviation; RNFL, retinal nerve fibre layer; VF, visual field. |
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