Rationale and impact
The committee agreed that the key outcome for adults with ocular hypertension (OHT) or chronic open angle glaucoma (COAG) was visual field progression that, in the long-term, could affect people's vision. Intraocular pressure (IOP) was considered to be a relevant surrogate outcome because lowering IOP can prevent the risk of optic nerve damage and sight loss. High-quality evidence showed that there is no meaningful difference between 360° selective laser trabeculoplasty (SLT) and eye drops in achieving a target IOP, health-related quality of life, risk of total adverse events, and treatment adherence. The evidence did show that that there were transient adverse events associated with SLT such as transient discomfort, blurred vision, photophobia and hyperaemia. It was also highlighted that there are rare complications associated with SLT. While rare events were not highlighted in the evidence, corneal failure is possible after SLT procedures. In people who have first-line treatment with eye drops compared with first-line 360° SLT, more people used eye drops and more people have more than 1 eye drop medication at 12 months.
The cost-effectiveness evidence showed that first-line treatment with 360° SLT was more effective and less costly compared with eye drops, with at least 90% probability of being the more cost-effective option. For costs, this result was driven by treatment involving 360° SLT costing less overall compared with eye drops alone. This is because the additional upfront costs of 360° SLT were outweighed by the accumulating costs of eye drops over time. For quality of life, 360° SLT resulted in a longer period without eye drops, or with fewer eye drops, and slightly slower estimated progression rates for glaucoma. Although no statistically significant direct benefit on quality of life was found in the trial, additional data on the natural history of glaucoma, which was incorporated into the cost-effectiveness analysis, suggests that quality of life was likely to be improved. The cost-effectiveness analysis included the costs and benefits of a second 360° SLT if the clinicians deemed it necessary. Even if 360° SLT was assumed to have the same clinical effectiveness as eye drops, it would still be a highly cost-effective treatment, because of the estimated reduction in overall costs.
Based on this evidence and their clinical experience, the committee recommended 360° SLT as first-line treatment for people with newly diagnosed OHT or newly diagnosed COAG. The recommendation excludes cases associated with pigment dispersion syndrome. This was because there was no evidence on the use of 360° SLT in people with pigment dispersion syndrome and the committee agreed that eye drop treatment is more suitable for those people. The recommendation lists information to give to people to help them make a decision on having SLT as first-line treatment, including telling them about 360° SLT‑specific side effects and complications and how long they are likely to last.
The committee noted that SLT may need to be repeated. This was included in the cost-effectiveness analyses (with approximately 15% of people in the SLT arm having a second procedure within the first year), which gave the committee more confidence in the result, as it reflected their expectations of how the treatment would be used in practice. The committee recommended that a second 360° SLT could be needed if the effect of an initial successful 360° SLT has subsequently reduced over time. This means that the IOP level has gone up and clinicians need to decide if there is risk of progression of COAG or conversion of OHT to COAG. The second 360° SLT should be given at the discretion of the responsible consultant ophthalmologist. This follows the procedure used in the main UK randomised trial (the LiGHT trial).
The committee further highlighted that in general, treatment to reduce IOP has to work for at least 6 months to be considered successful. However, this can also be based on clinician discretion.
The committee highlighted that there was a lack of long-term evidence on progression of glaucomatous visual field defect and progression of optic nerve head damage. The committee also highlighted that patients care more about vision outcomes than other outcomes such as IOP. A research recommendation was developed to cover this gap in the evidence on the long-term effectiveness of 360° SLT (with follow-up times of 3 years or more, 5 years and 10 years).
The committee considered the impact of recommending 360° SLT on other recommendations in the guideline. Recommendations were amended as necessary, taking into account the original evidence for each recommendation and the committee's knowledge and experience.
The recommendations are likely to result in a significant change in practice, because more people with newly diagnosed OHT or COAG could be offered 360° SLT as their first treatment. The committee also noted that larger centres may see more referrals, resulting in an increase in the number of clinics per week. The committee highlighted that, although the increase should not be significant, any increase means there will be a change to the organisation of care. Overall, this is not likely to have a substantial cost impact because evidence shows that first-line 360° SLT (including the purchase and maintenance of the SLT machine) was less costly than first-line use of eye drops. However, there will be changes in the types of costs incurred, with significant reductions in the cost of eye drop prescriptions but increases in costs for SLT devices and staffing.
The 2017 guideline recommended prostaglandin analogue (PGA) eye drops for OHT or COAG. The committee amended this to reflect the new 2022 recommendations on using 360° SLT. They agreed that people who prefer not to have 360° SLT or for whom it is not suitable should be offered generic PGA eye drops. This was because PGA eye drops were used for first-line treatment in the 2017 guideline and in the LiGHT trial.
The recommendations were also amended to highlight that eye drop installation technique should be demonstrated and that healthcare professionals should observe the person to confirm that their installation technique is correct. It is recommended that this be done when eye drops are first prescribed.
The committee noted that the first-line use of 360° SLT to treat OHT or COAG might lead to a significant change in practice that requires different organisation of care and the establishment of a multidisciplinary team. The committee wanted to make clear that if 360° SLT is suitable for a person, that person should be referred to a consultant ophthalmologist. They also discussed the safety of the 360° SLT procedure and agreed that healthcare professionals should discuss with the responsible consultant ophthalmologist the decision to offer it and how it will be performed. This means that with support from a consultant ophthalmologist, healthcare professionals such as specialty doctors, associate specialists, specialist nurses, optometrists and allied health professionals can perform 360° SLT.
The committee also noted that healthcare professionals who provide 360° SLT should be given support and have relevant training on the suitability and safety of the procedure, including its benefits and risks. They should also be trained in discussing these points and patient consent with patients and their family members or carers. A similar approach was taken in the LiGHT trial, in which training was given to all treating surgeons before recruitment, and the chief investigator, who was a consultant ophthalmic surgeon, observed each surgeon perform at least 1 laser treatment. Based on these discussions, new recommendations were added to provide further clarification on organisation of care.
The recommendations are likely to result in a significant change in practice because training and support will be needed for healthcare professionals performing the 360° SLT procedure.