Effectiveness of Lens Extraction with Intraocular Lens Implantation for the treatment of Primary Angle Closure Glaucoma
Lead Research Organisation:
University of Aberdeen
Department Name: School of Medical Sciences
Abstract
The purpose of this study is to test which treatment is best for people with an eye condition called primary angle closure glaucoma (PACG).
PACG is a leading cause of irreversible blindness worldwide. In PACG the eye’s ability to drain is damaged leading to an elevation of the pressure within the eye. High pressure leads to visual loss and, if untreated, blindness. The risk of blindness is greatly reduced by lowering this pressure.
Current treatment is to use a laser to open the drainage pathways, eye drops to reduce the eye pressure and, if these fail, drainage surgery within the eye. It is thought that PACG might be more successfully treated by removing the lens of the eye and replacing it with a plastic lens (commonly known as cataract surgery). Early lens extraction, potentially, could reduce the number of eye drops required and overall improve vision compared with current treatments.
As there is no high quality research assessing whether removing the lens at an early stage, i.e. when there is no cataract, is better than standard treatment, this international study will randomly allocate participants to either treatment and assess the quality of life, vision and associated costs three years later.
PACG is a leading cause of irreversible blindness worldwide. In PACG the eye’s ability to drain is damaged leading to an elevation of the pressure within the eye. High pressure leads to visual loss and, if untreated, blindness. The risk of blindness is greatly reduced by lowering this pressure.
Current treatment is to use a laser to open the drainage pathways, eye drops to reduce the eye pressure and, if these fail, drainage surgery within the eye. It is thought that PACG might be more successfully treated by removing the lens of the eye and replacing it with a plastic lens (commonly known as cataract surgery). Early lens extraction, potentially, could reduce the number of eye drops required and overall improve vision compared with current treatments.
As there is no high quality research assessing whether removing the lens at an early stage, i.e. when there is no cataract, is better than standard treatment, this international study will randomly allocate participants to either treatment and assess the quality of life, vision and associated costs three years later.
Technical Summary
Primary angle closure glaucoma (PACG) is a leading cause of irreversible blindness worldwide. In the UK, PACG is estimated to cause blindness in 1000 people every year, and direct costs to the NHS of treating PACG are in excess of #25 million per annum. This proposed single masked randomised controlled trial (RCT) of 400 participants in the UK and East Asia investigates the clinical and cost-effectiveness of early clear lens extraction for the treatment of PACG. Early clear lens extraction will be compared with current standard care (laser iridotomy followed by a sequence of medical therapy, laser iridoplasty and trabeculectomy), which is associated with suboptimal outcomes.
Eligible patients will be randomised to receive either early clear lens extraction or standard care. Patients with PACG with at least 180 degrees of appositional or synechial closure, uncontrolled intraocular pressure (IOP), and aged 50 or over will be eligible. The exclusion criteria include advanced glaucoma, ocular co-morbidity that would make lens extraction unsafe or impossible to do, previous cataract surgery, or current cataract. Both eyes per participant will be included, if both eyes are eligible.
The trial will assess the effect of the intervention on 3 dimensions of outcomes ? patient health status (using the EQ-5D); clinical effectiveness using IOP at the 3 years post surgery; and cost effectiveness using the incremental cost per quality adjusted life year (QALY) gained. The study is adequately powered to address each component individually and the use of these reflects the multidimensional nature of the possible effects the intervention may have (patient centred, clinical and economic).
Recruitment will take place in 20 centres over 2 years, and the study is projected to last 63 months in total. An economic evaluation will be an integral component of the study. Those randomised to surgery will be operated on within 8 weeks of randomisation, and if the second eye is eligible surgery will be within a further 8 weeks. The study will be led from Aberdeen by an experienced multidisciplinary team of health services researchers and trialists.
If the intervention proves to have better clinical and economic outcomes than standard care the treatment of PACG will be modified, potentially improving the quality of life of patients and reducing the incidence of blindness in the UK and worldwide.
Eligible patients will be randomised to receive either early clear lens extraction or standard care. Patients with PACG with at least 180 degrees of appositional or synechial closure, uncontrolled intraocular pressure (IOP), and aged 50 or over will be eligible. The exclusion criteria include advanced glaucoma, ocular co-morbidity that would make lens extraction unsafe or impossible to do, previous cataract surgery, or current cataract. Both eyes per participant will be included, if both eyes are eligible.
The trial will assess the effect of the intervention on 3 dimensions of outcomes ? patient health status (using the EQ-5D); clinical effectiveness using IOP at the 3 years post surgery; and cost effectiveness using the incremental cost per quality adjusted life year (QALY) gained. The study is adequately powered to address each component individually and the use of these reflects the multidimensional nature of the possible effects the intervention may have (patient centred, clinical and economic).
Recruitment will take place in 20 centres over 2 years, and the study is projected to last 63 months in total. An economic evaluation will be an integral component of the study. Those randomised to surgery will be operated on within 8 weeks of randomisation, and if the second eye is eligible surgery will be within a further 8 weeks. The study will be led from Aberdeen by an experienced multidisciplinary team of health services researchers and trialists.
If the intervention proves to have better clinical and economic outcomes than standard care the treatment of PACG will be modified, potentially improving the quality of life of patients and reducing the incidence of blindness in the UK and worldwide.