Selective laser trabeculoplasty versus 0·5% timolol eye drops in the management of glaucoma in Tanzania
Authors: Olusola Olawoye, Daniel Etya'ale
Journal: The Lancet Global Health (2021)

Africa has the highest prevalence of glaucoma blindness worldwide.1GBD 2019 Blindness and Vision Impairment CollaboratorsCauses of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study.Lancet Glob Health. 2021; 9: e144-e160Summary Full Text Full Text PDF PubMed Scopus (260) Google Scholar Factors such as insufficient awareness and knowledge about the disease, poverty of resources, competing individual needs, scarce access to affordable treatment, low ophthalmologist to population ratio, ineffective government policies, and collapse of primary health-care services in many countries2Kyari F Gilbert C Blanchet K Wormald R Improving services for glaucoma care in Nigeria: implications for policy and programmes to achieve universal health coverage.Br J Ophthalmol. 2017; 101: 543-547Crossref PubMed Scopus (8) Google Scholar all contribute to the burden of this condition in sub-Saharan Africa. Evidence for the efficacy of laser surgery as first-line therapy of glaucoma, compared with topical medications, was first reported in the Glaucoma Laser Trial in 1990.3The Glaucoma Laser Trial (GLT)2. Results of argon laser trabeculoplasty versus topical medicines. The Glaucoma Laser Trial Research Group.Ophthalmology. 1990; 97: 1403-1413Summary Full Text PDF PubMed Scopus (208) Google Scholar The study showed that argon laser trabeculoplasty was more efficacious than was topical timolol in newly diagnosed patients with primary open-angle glaucoma. A 2019 study, the LiGHT trial by Gazzard and colleagues,4Gazzard G Konstantakopoulou E Garway-Heath D et al.Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial.Lancet. 2019; 393: 1505-1516Summary Full Text Full Text PDF PubMed Scopus (182) Google Scholar also provided evidence for the use of selective laser trabeculoplasty (SLT) as first-line treatment in patients with open-angle glaucoma and ocular hypertension. The trial showed that, compared with first-line prostaglandin analogues, second-line β blockers, and third-line or fourth-line topical carbonic anhydrase inhibitors or α agonists, SLT as first-line therapy was safe and cost-effective, and provided superior intraocular pressure reduction and stability, making it more clinically effective. However, the majority of participants (70%) in the LiGHT trial were of European descent, and the visual field median deviation at baseline was consistent with early-to-moderate glaucoma. Furthermore, Realini and colleagues5Realini T Shillingford-Ricketts H Burt D Balasubramani GK West Indies Glaucoma Laser Study (WIGLS): 1. 12-month efficacy of selective laser trabeculoplasty in Afro-Caribbeans With glaucoma.Am J Ophthalmol. 2017; 184: 28-33Summary Full Text Full Text PDF PubMed Scopus (22) Google Scholar reported a success rate of 78% at 12 months, with a mean intraocular pressure drop of 29·7–39·5% following SLT in African Caribbean individuals with primary open-angle glaucoma. Studies in sub-Saharan Africa have also reported the efficacy of SLT.6Goosen E Visser L Sartorius B Selective laser trabeculoplasty in primary open-angle glaucoma: primary versus secondary treatment outcomes.African Vis Eye Heal. 2016; 75: a338Google Scholar, 7Seck SM Agboton G Dieng M et al.La trabéculoplastie au laser sélectif (TLS): notre expérience chez le noir africain.J Fr Ophtalmol. 2015; 38: 238-246Crossref PubMed Scopus (15) Google Scholar One study was conducted in South Africa, with Black South African (n=60), Indian (n=21), and White (n=3) participants.6Goosen E Visser L Sartorius B Selective laser trabeculoplasty in primary open-angle glaucoma: primary versus secondary treatment outcomes.African Vis Eye Heal. 2016; 75: a338Google Scholar This study did not compare SLT with medications; instead, it only reported the efficacy of SLT in treatment-naive patients and in those already receiving medications or surgery. A second study was performed in Senegal among Senegalese patients with primary open-angle glaucoma, and reported the efficacy of SLT.7Seck SM Agboton G Dieng M et al.La trabéculoplastie au laser sélectif (TLS): notre expérience chez le noir africain.J Fr Ophtalmol. 2015; 38: 238-246Crossref PubMed Scopus (15) Google Scholar An evidence-based, cost-effective glaucoma treatment modality in sub-Saharan Africa is likely to provide a framework change in the setting of glaucoma management. The trial by Heiko Philippin and colleagues8Philippin H Matayan E Knoll KM Selective laser trabeculoplasty versus 0·5% timolol eye drops for the treatment of glaucoma in Tanzania: a randomised controlled trial.Lancet Glob Health. 2021; (published online Oct 13.)https://doi.org/10.1016/S2214-109X(21)00348-XSummary Full Text Full Text PDF PubMed Scopus (5) Google Scholar compared the efficacy of SLT with that of 0·5% timolol eye drops in patients with advanced glaucoma in Tanzania. SLT, which is a more convenient treatment option, was performed once (or twice, if unsuccessful the first time) in the 12 months of the study and had a superior efficacy to twice daily application of 0·5% timolol eye drops (and repeat counselling when necessary) at 12 months. At the end of 12 months, the estimated odds for success using SLT were 3·37 times higher than those using timolol. SLT was not only efficacious but also cost-effective. These findings are relevant in the management of glaucoma in sub-Saharan Africa, where cost-effectiveness and convenience are crucial to successful patient management. Some of the strengths of this study lie in the population in which it was performed (ie, African participants residing within sub-Saharan Africa); the advanced stage of glaucoma at baseline, which is the most prevalent form of glaucoma at presentation in sub-Saharan Africa; the use of timolol, which is the cheapest medication available in most of the region; and the evidence of SLT's cost-effectiveness. Using a not-for-profit eye care service model, this study performed a cost-effectiveness analysis on the use of SLT and showed that the procedure could be performed for US$12·49 per treatment, and would be cost-effective if performed on 250–400 patients per year. It is pertinent to note that the study considered the cost of technicians travelling to maintain the equipment in its cost-effectiveness analysis, an important aspect of equipment management in sub-Saharan Africa. The enrolment of both eyes of a participant (if eligible), with adjustment for the correlation between them, made efficient use of available data. Although this study adds to existing knowledge about the use of SLT in the management of patients with glaucoma in sub-Saharan Africa, it is important to contextualise its findings within the region. For example, patients treated with SLT only, who attend clinics once or twice and are not given medications, might falsely believe that they have been successfully treated and do not need further monitoring, which could consequently risk them being lost to follow-up. Patients with chronic diseases who do not take medications might be at an increased risk of not adhering to clinical follow-up.9Paterson B Charlton P Richard S Non-attendance in chronic disease clinics: a matter of non-compliance?.J Nurs Healthc Chronic Illn. 2010; 2: 63-74Crossref Google Scholar Another issue from the practical standpoint is that many African patients with advanced glaucoma require multiple medications rather than 0·5% timolol alone. Considering how glaucoma affects an individual over a lifetime, the results of a longer follow-up would be valuable. Overall, the study by Philippin and colleagues8Philippin H Matayan E Knoll KM Selective laser trabeculoplasty versus 0·5% timolol eye drops for the treatment of glaucoma in Tanzania: a randomised controlled trial.Lancet Glob Health. 2021; (published online Oct 13.)https://doi.org/10.1016/S2214-109X(21)00348-XSummary Full Text Full Text PDF PubMed Scopus (5) Google Scholar is a well designed trial that provides important evidence for the use of SLT in the treatment of glaucoma in sub-Saharan Africa. The findings are an important advocacy tool for policy makers in the Ministries of Health and public tertiary institutions across this region. We declare no competing interests. Selective laser trabeculoplasty versus 0·5% timolol eye drops for the treatment of glaucoma in Tanzania: a randomised controlled trialSLT was superior to timolol eye drops for managing patients with open-angle high-pressure glaucoma for 1 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. Full-Text PDF Open Access