Selective Laser Trabeculoplasty Outcomes in Northern Ghana
Selective Laser Trabeculoplasty in Northern Ghana
J Simon¹, T Kenny², I Murdoch³*
- Director, Northern Community Eye Hospital, BA 108 Chinkara St, Rice City, Gumani, Tamale, Ghana NS-151-7998.
- Retired General Practitioner, United Kingdom.
- Honorary Associate Professor, Institute of Ophthalmology, University College London, UK.
[email protected]
OPEN ACCESS
PUBLISHED: 31 January 2025
CITATION: Simon, J., Kenny, T., et al., 2024. Selective Laser Trabeculoplasty in Northern Ghana. Medical Research Archives, [online] 13(1).
https://doi.org/10.18103/mra.v13i1.6141
COPYRIGHT: © 2025 European Society of Medicine. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
DOI https://doi.org/10.18103/mra.v13i1.6141
ISSN 2375-1924
ABSTRACT
We report on a audit in Northern Ghana. A total of 283 selective laser trabeculoplasties (SLTs) were performed between September 2021 and September 2024. Because of co-linearity between right and left eye response therapy, 145 eyes individuals with primary open angle glaucoma were included in the analysis. Outcomes were assessed at 1, 3, and 12 months post index procedure. A success proportion of 75% (33/44) for a ≥20% reduction in IOP was achieved. No complications occurred in this cohort. This is comparable to other studies in the literature.
Keywords
Selective Laser Trabeculoplasty, Glaucoma, Intraocular Pressure, Northern Ghana
Introduction
Glaucoma, as a group of chronic ocular diseases characterized by progressive optic nerve damage and visual field loss. The most prevalent is primary open angle glaucoma, which is a significant public health concern worldwide, including in Ghana. The principal therapy for primary open angle glaucoma is the lowering of intraocular pressure. This can be done by medicine, surgery or laser. Selective Laser Trabeculoplasty (SLT) has emerged as a minimally invasive and effective treatment option for open angle glaucoma. Like its predecessor argon laser trabeculoplasty, SLT targets the trabecular meshwork. It uses a large spot size with low energy, which purportedly reduces the risk of damage to surrounding tissue. YAG it delivers a fraction (about 1%) of the energy. Both have similar mechanisms of action but SLT does not result in reduction of the intraocular pressure.
Inclusion criteria
1. Primary open angle glaucoma (POAG), pseudoexfoliative glaucoma, pigmentary glaucoma, secondary glaucoma (e.g. ischemic, diabetic, neovascular, steroid-induced, rubiosis, trauma, etc.)
2. Any contraindication to SLT (e.g. unable to sit at the laser-mounted slit-lamp, past history of or active uveitis, inadequate visualization of trabecular meshwork)
3. Congenital or early-onset glaucoma
4. Visually significant cataract with intention to undergo cataract surgery in the subsequent year
5. Recent cataract surgery within 3 months
6. Any active treatment for another ophthalmic disease
7. Any history of retinal ischemia, macular oedema, diabetic retinopathy, age-related macular degeneration
8. Any previous intraocular surgery, except uncomplicated cataract surgery more than 3 months prior to recruitment
9. Pregnancy at the time of recruitment, or intention to become pregnant within the duration of the trial
| Criteria | Inclusion | Exclusion |
|---|---|---|
| Primary open angle glaucoma | Yes | No |
| Recent cataract surgery within 3 months | No | Yes |
| Any active treatment for another ophthalmic disease | No | Yes |
| Visually significant cataract | Yes | No |
Of these 145, 61 eyes (figure 1) had pre-treatment IOP during the first year, where the mean (SD) pre-treatment IOP was 18.2 (±4.2) mmHg. The mean age at the time of SLT was 67 years (SD 16) ranging from 46-92 years. 22 eyes had repeat SLT during the first year (figure 1). The mean (SD) IOP at 1, 2 months, 5 months was 14.5 (±3.6), 12.5 (±3.2) and 12.5 (±3.3) mmHg respectively.
Discussion
The landmark paper for SLT in the African context is Philippin et al.⁵ Their criteria for success however differed from ours. Only eyes with presenting IOPs above 21mmHg were included in the trial, both eyes in an individual were eligible and success was two tiered at <18mmHg in those with ‘severe’ glaucoma and <21mmHg in those with less severe glaucoma. On this basis the closest comparator would be any reduction in IOP in our cohort. At one year they reported reduction of IOP in 61% (99/163) eyes. Our finding of 75% (33/44) is directly comparable, as is our finding in the entire population of the same proportion at final time point of examination (75% (108/145)). In Caucasian populations the landmark study is the LiGHT study.⁴ This study was designed primarily for quality-of-life outcomes and the outcomes were given at 36 months post index SLT. IOP success was defined as achieving ‘target IOP’ meaning this would be likely to more stringent that any-drop and possibly not as stringent as ≥20%. Either way the success proportion with SLT and medications if needed (as in our study) was 93% at visits during the study which is in considerable excess of our success proportion. Thus our results seem comparable in an African context and below the success proportion in a Caucasian population. It should be noted that on the survival plot the success proportion at 1 year had reduced to 25% this is less appealing. None-the-less there seems to be a clear place for this therapy in an African setting since the advantages of no expense and supply chain requirement for topical therapy are especially appealing. The duration of effect will need ongoing studies to enable mature clinical decision making in creating therapeutic plans for patients.
This audit reflects real life challenges in managing chronic conditions such as glaucoma in this environment. Distance, expense and other factors contribute to the poor proportions of individuals returning for repeat review. It has been noted many times before that the asymptomatic aspect of glaucoma until the very end stages, is a major disadvantage in this respect. The lack of awareness of the disease has been documented in Ghana and elsewhere.⁷⁸ Perhaps the use of local terms for glaucoma⁹ may be of some assistance. Other
public health initiatives may also help. The poor follow-up is also a disadvantage in reporting results of interventions since it introduces potentially large unquantifiable bias.
Our analysis showed a striking correlation in the response of fellow eyes in an individual to SLT which was not there when eyes from separate individuals were compared. This means any analysis of outcome needs to either be of single eyes from individuals, meaning the data points are truly independent, or else random effects or other statistical techniques need to be applied to allow for the correlation and prevent an over estimation of sample size.¹⁰ The other striking observation is that the time point analysis considerably over-estimated the success proportions compared to time points in the survival analyses. We have also noted this observation in another study.¹¹ This highlights the care to be taken when critically appraising work that only presents time point analysis.
Conclusion
We report an audit of SLT undertaken in Northern Ghana with a 75% success proportion comparable in an African context but lower than Caucasian studies. Our analyses showed a striking correlation in the response of fellow eyes in an individual to SLT which was not there when eyes from separate individuals were compared. This means any analysis of outcomes needs to either be of single eyes from individuals, or else random effects or other statistical techniques need to be applied to allow for the correlation and prevent an over estimation of sample size.
Conflict of Interest:
None
Funding Statement:
None.
Acknowledgements:
None.
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