Onchocerciasis: a potential risk factor for glaucoma

BACKGROUND

Onchocerciasis is a microfilarial disease that causes ocular disease and blindness. Previous evidence of an association between onchocerciasis and glaucoma has been mixed. This study aims to further investigate the association between onchocerciasis and glaucoma.

METHODS

All subjects were patients at the Bishop John Ackon Christian Eye Centre in Ghana, west Africa, undergoing either trabeculectomy for advanced glaucoma or extracapsular extraction for cataracts, who also had a skin snip biopsy for onchocerciasis. A cross sectional case-control study was performed to assess the difference in onchocerciasis prevalence between the two study groups.

RESULTS

The prevalence of onchocerciasis was 10.6% in those with glaucoma compared with 2.6% in those with cataracts (OR, 4.45 (95% CI 1.48 to 13.43)). The mean age in the glaucoma group was significantly younger than in the cataract group (59 and 65, respectively). The groups were not significantly different with respect to sex or region of residence. In models adjusted for age, region, and sex, subjects with glaucoma had over three times the odds of testing positive for onchocerciasis (OR, 3.50 (95% CI 1.10 to 11.18)).

CONCLUSIONS

This study has shown a positive association between subclinical onchocerciasis and glaucoma. This finding emphasises the importance of eradication of onchocerciasis from west Africa.

Diode laser transscleral cyclophotocoagulation as a primary surgical treatment for primary open-angle glaucoma

OBJECTIVES

To evaluate the feasibility of diode laser transscleral cyclophotocoagulation (TSCPC) as a primary surgical treatment for primary open-angle glaucoma and to compare 2 laser energy settings used for treatment.

METHODS

In a prospective clinical trial in Cape Coast and Accra, Ghana, 1 eye of each of 92 patients with primary open-angle glaucoma was treated by diode laser TSCPC as a primary surgical treatment. Eyes were randomly assigned to receive treatment by 20 applications of either 1.5 W applied for 1.5 seconds or 1.25 W applied for 2.5 seconds.

RESULTS

Seventy-nine (86%) of 92 patients completed 3 months of follow-up; follow-up was 13.2 +/- 6.0 months (mean +/- SD). Intraocular pressure decreased in 53 (67%) of the 79 eyes. The drop in intraocular pressure was 20% or more in 37 eyes (47%) and final intraocular pressure was 22 mm Hg or less in 38 eyes (48%). An atonic pupil was a previously unreported complication that arose in 27 (28%) of 92 eyes. There were no serious complications of hypotony, phthisis bulbi, or sympathetic ophthalmia. Visual acuity decreased in 18 (23%) of 79 eyes treated by TSCPC and in 10 (23%) of 47 fellow eyes treated only with glaucoma medications. There was no difference in outcomes between the 2 laser energy settings.

CONCLUSIONS

Diode laser TSCPC is a practical, rapid, well-tolerated procedure that may provide a modest and variable lowering of intraocular pressure. The treatment, used with conservative energy levels applied to the eye, seems to have few serious complications, although a previously unrecognized complication of atonic pupil needs further evaluation. A moderate variation in laser energy settings does not influence the results of treatment.

Trabeculectomy with intraoperative 5-fluorouracil vs mitomycin C

PURPOSE

To compare the effectiveness of intraoperative 5-fluorouracil (5-FU) and mitomycin C used adjunctively with trabeculectomy in a black West African population.

METHODS

Eighty-five consecutive eyes of 85 black patients undergoing primary trabeculectomy for open-angle glaucoma were prospectively randomly assigned to receive either 5-FU (50 mg/ml for 5 minutes) or mitomycin C (0.5 mg/ml for 3 1/2 minutes) intraoperatively by soaked sponge.

RESULTS

Of the 81 eyes with at least a 3-month postoperative follow-up, 41 of 44 (93.2%) in the mitomycin C group and 27 of 37 (73.0%) in the 5-FU group had a final intraocular pressure of less than 21 mm Hg (P = .01). Twenty-eight of 44 eyes (63.6%) in the mitomycin C group and 18 of 37 (51.4%) in the 5-FU group had a final intraocular pressure of less than 15 mm Hg (P = .26). Mean postoperative intraocular pressure was 13.7 mm Hg in the mitomycin C group and 16.3 mm Hg in the 5-FU group (P = .05). There were no differences between the two groups in mean age, preoperative intraocular pressure, postoperative visual acuity, and complications. Mean follow-up was 10.0 +/- 4.41 months (range, 4 to 19 months).

CONCLUSIONS

The adjunctive use of mitomycin C with trabeculectomy is equally safe and more efficacious compared to 5-FU in this West African population. Use of mitomycin C in this study was not associated with a statistically significantly greater proportion of patients achieving low intraocular pressure (less than 15 mm Hg) compared to 5-FU.

A prospective trial of intraoperative fluorouracil during trabeculectomy in a black population

In a study population of black Africans with advanced glaucoma in Ghana we conducted a prospective study of intraoperative 5-fluorouracil alone. Eyes undergoing trabeculectomy were randomly selected either to receive or not receive a single intraoperative application of 5-fluorouracil (50 mg/ml for five minutes). Fifty-five eyes had a mean follow-up of 282 days (minimum, 92 days). Twenty of 24 eyes (83%) in the 5-fluorouracil group vs 12 of 31 eyes (39%) in the control group had postoperative intraocular pressure of 20 mm Hg or less with or without medical therapy (P = .01). Eleven of 24 eyes (46%) in the 5-fluorouracil group and five of 31 eyes (16%) in the control group had intraocular pressure of 15 mm Hg or less (P = .02). Without medical therapy, 17 of 24 eyes (71%) in the 5-fluorouracil group and ten of 31 eyes (32%) in the control group had intraocular pressure of 20 mm Hg or less (P = .02). The overall complications were similar in the two groups. In this population, intraoperative 5-fluorouracil markedly improved the ability of trabeculectomy to lower intraocular pressure. We recommend that intraoperative 5-fluorouracil be considered in glaucoma surgery with poor prognosis as an alternative to postoperative subconjunctival injections when multiple injections are not feasible.