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Primary open angle glaucoma case finding in a UK community

Chan, Michelle Pui Yan; (2020) Primary open angle glaucoma case finding in a UK community. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Glaucoma is a leading cause of irreversible blindness in the UK, and generates the sixth largest share of NHS outpatient attendances. There are inadequacies in the current system of primary open angle glaucoma (POAG) case-finding and its referral to the hospital eye service (HES). Half the cases are undiagnosed, while a large proportion of referrals for raised intraocular pressure (IOP) (>21mmHg) do not have glaucoma. No diagnostic test exists with both sufficient sensitivity and specificity suitable for population-wide glaucoma screening. The EPIC-Norfolk Eye Study is a cross-sectional ophthalmic survey. This thesis aims to explore the characteristics of POAG, the risk factors for undiagnosed POAG, to re-examine the IOP referral threshold, and to evaluate the diagnostic performances of optic disc imaging in population screening. Among the 8623 participants, 4.2% had glaucoma and 3.7% had POAG. A large number were glaucoma suspects (7%) and ocular hypertensives (10%). POAG was strongly associated with higher corneal compensated IOP (IOPcc) and lower corneal hysteresis, which could become useful metrics in disease management. 34% of POAG cases were previously undiagnosed, the risk factors were having normal tension rather than high tension glaucoma, lower pre-treatment IOP and smaller cup/disc ratio. This suggests an over-reliance on IOP in diagnosis and the need to re-focus on disc assessment. The upper limit of IOP distribution (mean+2 standard deviations) in the study was 23.6mmHg. Increasing the referral threshold to >24mmHg could cut HES referrals by up to 67%. IOP used alone is ineffective in diagnosing POAG. HRTII and GDx-VCC used in combination generated high sensitivities and specificities in glaucoma screening, but would be costly and impractical to implement. The individual normative values of HRTII and GDx-VCC generated low sensitivities but high specificities (>97.0%), and could be useful in excluding glaucoma on a population scale. These findings can help transform glaucoma care in the UK.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Primary open angle glaucoma case finding in a UK community
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author [year]. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10098645
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