To investigate the performance of scanning laser polarimetry and scanning laser ophthalmoscopy in glaucoma case finding
Lead Research Organisation:
University College London
Department Name: Institute of Ophthalmology
Abstract
Glaucoma is an eye disease in which the optic nerve is damaged, causing loss of vision. It is the commonest cause of irreversible blindness worldwide. It produces no symptoms until advanced, but abnormalities are detectable on examination from an early stage. However, there is no proven rapid test or combination of tests to screen for glaucoma. In the UK, many people undergo eye pressure measurement by an optician, but studies show that round 50% of glaucoma remains undetected in the community.
Scanning laser polarimetry (GDx) and Heidelberg Retinal Tomography (HRT) are imaging devices used to diagnose & monitor glaucoma. Respectively, they measure the thickness of the nerve fibre layer near the optic nerve, and analyse the contour of the optic nerve with computer software. They have the advantage of being fast, objective, reproducible and can be carried out by a technician.
This research aims to evaluate the combined use of GDx and HRT as screening tools for glaucoma. It will analyse existing data on residents of Norfolk. Many have undergone ophthalmological examination to determine if they have glaucoma or not. The practical application of the findings could be a more robust screening method, being able to identify those with glaucoma at an early stage.
Scanning laser polarimetry (GDx) and Heidelberg Retinal Tomography (HRT) are imaging devices used to diagnose & monitor glaucoma. Respectively, they measure the thickness of the nerve fibre layer near the optic nerve, and analyse the contour of the optic nerve with computer software. They have the advantage of being fast, objective, reproducible and can be carried out by a technician.
This research aims to evaluate the combined use of GDx and HRT as screening tools for glaucoma. It will analyse existing data on residents of Norfolk. Many have undergone ophthalmological examination to determine if they have glaucoma or not. The practical application of the findings could be a more robust screening method, being able to identify those with glaucoma at an early stage.
Technical Summary
Aims:
To investigate if optic disc/ retinal nerve fibre layer imaging is a viable method for glaucoma case finding.
Objectives:
1. To investigate the performance of scanning laser polarimetry (GDx) and scanning laser ophthalmoscopy (HRT) in glaucoma case finding in a community setting in the UK
2. To assess whether combination of GDx and HRT measures may enhance case finding performance
3. To explore whether additional demographic, socio-economic or ophthalmic features may be used to further enhance the performance of case finding.
Design:
The European Prospective Investigation of Cancer (EPIC) study is a large multi-centre cohort study looking at the connection between diet and cancer. One of the cohorts, EPIC-Norfolk, consisting of 30,446 men & women, was established in 1993. Since 2004, detailed eye examination data on 6,277 subjects aged 49 years and older have been gathered, and examination on 8,000 subjects is expected to be complete before the start of this project. The data includes among others, parameters for glaucoma assessment, such as visual acuity, intraocular pressure, retinal nerve fibre layer imaging with scanning laser polarimetry, optic nerve head tomography with Heidelberg HRT2, as well as disc & macular digital photographs. Participants with abnormal test results have been referred to a local NHS consultant ophthalmologist for a full examination and, if necessary, further management. Preliminary analysis indicates that only 29% of normal pressure glaucoma has been identified in the population of Norfolk.
Methods:
This project will examine the performance of HRT2, GDX and combinations of test using sensitivity, specificity, false positive and false negative rates, positive and negative predictive values, and receiver operating characteristic analyses, with 95% confidence intervals. We will explore the feasibility of individual tests and combinations of tests in data from 4,000 participants, and test the performance most successful model(s) using data from a different 4,000 participants. To quantify the false negative rates of these tests, optic disc photographs of all people aged 70 years and older and a proportion (5%) of those aged 49 to 69 years who were tested negative will be examined to detect undiagnosed glaucoma based on optic nerve structure.
To investigate if optic disc/ retinal nerve fibre layer imaging is a viable method for glaucoma case finding.
Objectives:
1. To investigate the performance of scanning laser polarimetry (GDx) and scanning laser ophthalmoscopy (HRT) in glaucoma case finding in a community setting in the UK
2. To assess whether combination of GDx and HRT measures may enhance case finding performance
3. To explore whether additional demographic, socio-economic or ophthalmic features may be used to further enhance the performance of case finding.
Design:
The European Prospective Investigation of Cancer (EPIC) study is a large multi-centre cohort study looking at the connection between diet and cancer. One of the cohorts, EPIC-Norfolk, consisting of 30,446 men & women, was established in 1993. Since 2004, detailed eye examination data on 6,277 subjects aged 49 years and older have been gathered, and examination on 8,000 subjects is expected to be complete before the start of this project. The data includes among others, parameters for glaucoma assessment, such as visual acuity, intraocular pressure, retinal nerve fibre layer imaging with scanning laser polarimetry, optic nerve head tomography with Heidelberg HRT2, as well as disc & macular digital photographs. Participants with abnormal test results have been referred to a local NHS consultant ophthalmologist for a full examination and, if necessary, further management. Preliminary analysis indicates that only 29% of normal pressure glaucoma has been identified in the population of Norfolk.
Methods:
This project will examine the performance of HRT2, GDX and combinations of test using sensitivity, specificity, false positive and false negative rates, positive and negative predictive values, and receiver operating characteristic analyses, with 95% confidence intervals. We will explore the feasibility of individual tests and combinations of tests in data from 4,000 participants, and test the performance most successful model(s) using data from a different 4,000 participants. To quantify the false negative rates of these tests, optic disc photographs of all people aged 70 years and older and a proportion (5%) of those aged 49 to 69 years who were tested negative will be examined to detect undiagnosed glaucoma based on optic nerve structure.