Laser treatment has the potential to transform the management of glaucoma in Africa, and to prevent more people from going irreversibly blind, particularly in regions with high disease prevalence and incidence, suggests research published in The Lancet Global Health.
Conducted in Tanzania, the research is the first randomised controlled trial exploring the use of the laser treatment, Selective Laser Trabeculoplasty (SLT), for patients with glaucoma in Sub-Saharan Africa.
Globally, glaucomas are the most frequent cause of irreversible blindness, caused by a build-up of fluid in the eye. Africa has the highest prevalence of the condition and highest prevalence of blindness due to glaucoma. Rates in Sub-Saharan Africa are predicted to nearly double by 2040.
Irreversible blindness caused by glaucoma can be prevented by reducing intraocular pressure through daily eye drops, eye surgery, or laser treatment. Currently timolol eye drops are the most affordable and commonly available treatments to reduce intraocular pressure.
The researchers found that SLT successfully reduced eye pressure to normal levels (up to 18 or 21mmHg) in significantly more patients after one year (61% of eyes) compared with the standard treatment of timolol eye drops (31% of eyes).
The study also considered the affordability of SLT, finding that in spite of the initial cost of the laser equipment, for hospitals dealing with high volumes of glaucoma patients the treatment could be offered at a similar price as the annual supply of eye drops.
The study was conducted by the International Centre for Eye Health (ICEH) at the London School of Hygiene & Tropical Medicine (LSHTM), in partnership with the Kilimanjaro Christian Medical Centre (KCMC) in Tanzania. It was funded by the international disability charity CBM (Christian Blind Mission) and the Seeing is Believing Innovation Fund.
Dr Heiko Philippin, Clinical Research Fellow at the ICEH at LSHTM and study lead, said: “Glaucoma requires life-long treatment and follow-up to save a person’s sight, which can be very challenging in many settings. Currently, most people are treated with eye drops but many struggle with taking them regularly or accessing new bottles, for example due to cost or distance to the nearest clinic.
“These study results are exciting because they show we can treat glaucoma more successfully with a one-off or occasionally repeated outpatient laser treatment to reduce eye pressure at least for one year, compared with the most commonly used eye drops in lower income regions. We are grateful to all participants and our colleagues for their commitment and hope that these findings will improve glaucoma care for many people at risk of becoming blind.”
Timolol eye drops are subject to erratic application, systemic and local side-effects, and high long-term costs due to the need for daily life-long treatment in settings where health insurance options are rare. The Lancet Global Health Commission on Global Eye Health called for research into cost-effective glaucoma interventions, especially those that are applicable in low- and middle-income countries.
Dr William Makupa, head of Ophthalmology at Kilimanjaro Christian Medical Centre, said: “In our setting glaucoma is diagnosed late, and some patients, after some time, decide to ignore or just stop using eye drops. If we can establish an alternative effective means of arresting the disease, we would bring about a positive impact on the quality of life of these patients.”
SLT is already widely used in high-income countries. During the treatment, about 100 laser spots are applied to the tissue at the base of the cornea, which is responsible for draining the fluid from the eye.
While previous trials have compared SLT and eye drops, this is the first to do so with predominantly advanced glaucoma patients and the first to compare SLT with timolol. The study also reflects the typical spectrum and associated challenges of glaucoma care in this region.
Of the patients enrolled, both eyes were included in the study if they met the trial criteria: 382 eyes in total. 100 patients (191 eyes) were treated with timolol eye drops and 101 patients (191 eyes) with SLT. After one year, data from 339 eyes were analysed. The eye drop treatment was successful in 31.3% (55/176 eyes), while SLT was successful in 60.7% (99/163 eyes).
Based on 500 eyes treated each year, and taking into account the cost of the equipment and maintenance, one SLT procedure would cost $12.49 in total, while annual therapy with timolol eye drops cost around $16.32 per eye in Tanzania. In this study 33 eyes required two SLT treatments, and 66 eyes were successfully treated after one procedure. Therefore, despite the initial costs of the laser equipment, they estimate around 500 SLT treatments would cost a similar price as timolol eye drops for hospitals dealing with high volumes of glaucoma patients.
Professor Matthew Burton, director of the ICEH at LSHTM, said: “This result is very important for improving glaucoma treatment in low- and middle-income countries. Poor eye health has a knock-on effect on poverty, employment and development. With the number of people affected by glaucoma set to rise, studies like these are crucial for identifying solutions that can tackle the challenge and improve the lives and livelihoods of those in Sub-Saharan Africa and beyond. Showing a significant improvement over the standard treatment for glaucoma is a real breakthrough for treating the disease in areas that historically struggle with treatment and adherence.”
The researchers acknowledge limitations of this study, including the follow-up time of one year, which allows the study of eye pressure reduction, safety, complications and cost, but is insufficient to verify differences in loss of sight and quality of life. This will require a longer follow-up period.
Study details
Selective laser trabeculoplasty versus 0·5% timolol eye drops for the treatment of glaucoma in Tanzania: a randomised controlled trial.
Heiko Philippin, Einoti Matayan, Karin M Knoll, Edith Macha, Sia Mbishi, Andrew Makupa, Cristóvão Matsinhe, Vasco da Gama, Mario Monjane, Awum Joyce Ncheda, Francisco Alcides Mulobuana, Elisante Muna, Nelly Fopoussi, Gus Gazzard, Ana Patricia Marques, Peter Shah, David Macleod, William U Makupa, Matthew J Burton.
Published in The Lancet Global Health on 13 October 2021
Summary
Background
Glaucoma is a major cause of sight loss worldwide, with the highest regional prevalence and incidence reported in Africa. The most common low-cost treatment used to control glaucoma is long-term timolol eye drops. However, low adherence is a major challenge. We aimed to investigate whether selective laser trabeculoplasty (SLT) was superior to timolol eye drops for controlling intraocular pressure (IOP) in patients with open-angle glaucoma.
Methods
We did a two-arm, parallel-group, single-masked randomised controlled trial at the Eye Department of Kilimanjaro Christian Medical Centre, Moshi, Tanzania. Eligible participants (aged ≥18 years) had open-angle glaucoma and an IOP above 21 mm Hg, and did not have asthma or a history of glaucoma surgery or laser. Participants were randomly assigned (1:1) to receive 0·5% timolol eye drops to administer twice daily or to receive SLT. The primary outcome was the proportion of eyes from both groups with treatment success, defined as an IOP below or equal to target pressure according to glaucoma severity, at 12 months following randomisation. Re-explanation of eye drop application or a repeat SLT was permitted once. The primary analysis was by modified intention-to-treat, excluding participants lost to follow-up, using logistic regression; generalised estimating equations were used to adjust for the correlation between eyes. This trial was registered with the Pan African Clinical Trials Registry, number PACTR201508001235339.
Findings
840 patients were screened for eligibility, of whom 201 (24%) participants (382 eligible eyes) were enrolled between Aug 31, 2015, and May 12, 2017. 100 (50%) participants (191 eyes) were randomly assigned to the timolol group and 101 (50%; 191 eyes) to the SLT group. After 1 year, 339 (89%) of 382 eyes were analysed. Treatment was successful in 55 (31%) of 176 eyes in the timolol group (16 [29%] of 55 eyes required repeat administration counselling) and in 99 (61%) of 163 eyes in the SLT group (33 [33%] of 99 eyes required repeat SLT; odds ratio 3·37 [95% CI 1·96–5·80]; p<0·0001). Adverse events (mostly unrelated to ocular events) occurred in ten (10%) participants in the timolol group and in eight (8%) participants in the SLT group (p=0·61).
Interpretation
SLT was superior to timolol eye drops for managing patients with open-angle high-pressure glaucoma for one year in Tanzania. SLT has the potential to transform the management of glaucoma in sub-Saharan Africa, even where the prevalence of advanced glaucoma is high.
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