Glaucoma Management in the African-Derived Developing World Using Trabeculoplasty

Glaucoma is a leading cause of blindness in the African-derived developing world and
represents a significant public health challenge as the disease burden is substantial. In
Ghana, the prevalence of open-angle glaucoma over age 40 is 8.5%. In Barbados, the
prevalence is 7.0%. In neighboring St. Lucia, the prevalence has been estimated at 8.8% with
a 16% ten-year incidence of glaucoma-related blindness in one or both eyes. (In contrast,
the prevalence in US adults is 1.9%.) The burden of glaucoma-related visual dysfunction is
also substantial in the developing world. Because the application of medical and surgical
therapies is limited by issues such as cost, availability, and limited regional surgical
expertise, undertreatment is pervasive. Also, there is little access to low vision or vision
rehabilitation services and minimal social support for the visually impaired. Laser
trabeculoplasty may be a part of the solution to the developing world's burgeoning glaucoma
burden. The treatment is fast, safe, minimally invasive and requires minimal post-treatment
care; the equipment is portable; and the incremental cost of trabeculoplasty treatment is
small once the equipment and expertise are on-site. Our recent study in St. Lucia
demonstrated that laser trabeculoplasty lowers IOP by an amount likely to favorably alter
the clinical course of glaucoma (versus no treatment) and has the potential to bend the
glaucoma-related blindness curve in the African-derived developing world. Our long-term goal
is to translate this finding through a public health initiative by establishing a
pan-Caribbean glaucoma laser program to provide safe, effective, and cost-effective therapy
for glaucoma in this underserved and overburdened region. Before this can happen, several
important research questions remain unanswered regarding SLT in this population and comprise
the specific aims of this proposal. What is the long-term efficacy of SLT in this
population? Is repeat SLT effective once the IOP reduction of initial SLT wanes? Are the
results obtained in St. Lucia generalizable to other developing nations populated by people
of African descent? In this application, we propose a prospective cohort study in St. Lucia
in which qualifying subjects with open-angle glaucoma will receive bilateral selective laser
trabeculoplasty, will be followed to failure of initial SLT, and will undergo repeat SLT and
again be followed to failure. The long-term safety and efficacy of both initial and repeat
SLT in glaucoma patients of African descent will thus be established. Further, we will
replicate the cohort study in Dominica to confirm external validity of the St. Lucia
outcomes. This proposal is designed to answer the questions posed above and thus to complete
the research phase of this project and facilitate translation of the research findings into
the public health space. Considering the population of the African-derived developing world,
the prevalence of glaucoma in this population, and the observed preliminary benefits of
laser therapy, this project's output could ultimately reduce the risk of glaucoma-related
visual dysfunction in hundreds of thousands of individuals throughout the developing world.

Inclusion Criteria:

- Afro-Caribbean ancestry

- Ages 30 and above

- Open-angle glaucoma (ISGEO criteria)

- CDR≥0.7 or CDR asymmetry ≥0.2 or rim width ≤0.1 CDR with typical VF loss; or

- CDR≥0.8 or CDR asymmetry ≥0.3 (if unable to get VF); or

- VA <20/400 and IOP ≥ 32 mmHg (if unable to get VF or CDR)

- Receiving ≤2 topical IOP-lowering medications

- IOP between 17-35 mmHg in both eyes after 30-day washout

Exclusion Criteria:

- Any glaucoma other than open-angle glaucoma

- Advanced glaucoma (CDR > 0.9 or field loss in central 10º)

- History of:

- Prior glaucoma laser or surgery

- Ocular inflammation within 3 months

- Ocular trauma or intraocular surgery within 6 months