Sustainable Control of Onchocerciasis: Ocular Pathology in Onchocerciasis Patients Treated Annually with Ivermectin for 23 Years: A Cohort Study

The evolution and persistence of ocular pathology was assessed in a cohort of Onchocerca volvulus infected patients treated annually with ivermectin for 23 years. Patients were resident in rural Central and Kara Region of Togo and ocular examinations included testing of visual acuity, slit lamp examination of the anterior eye segment and the eye fundus by ophthalmoscopy. Before ivermectin treatment, vivid O.volvulus microfilariae (MF) were observed in the right and left anterior eye chamber in 52% and 42% of patients (n = 82), and dead MF were seen in the right and left cornea in 24% and 15% of cases, respectively. At 23 years post initial treatment (PIT), none of the patients (n = 82) presented with MF in the anterior chamber and cornea. A complete resolution of punctate keratitis (PK) lesions without observable corneal scars was present at 23 years PIT (p<0.0001), and sclerosing keratitits (SK) lessened by half, but mainly in patients with lesions at early stage of evolution. Early-stage iridocyclitis diminished from 42%(rE) and 40%(lE) to 13% (rE+lE)(p<0.0001), but advanced iridocyclitis augmented (p<0.001) at 23 years PIT compared to before ivermectin. Advanced-stage papillitis and chorioretinitis did not regress, while early-stage papillitis present in 28%(rE) and 27%(lE) of patients at before ivermectin regressed to 17%(rE) and 18%(lE), and early-stage chorioretinitis present in 51%(rE+lE) of cases at before ivermectin was observed in 12%(rE) and 13%(lE) at 23 years PIT (p<0.0001). Thus, regular annual ivermectin treatment eliminated and prevented the migration of O. volvulus microfilariae into the anterior eye chamber and cornea; keratitis punctata lesions resolved completely and early-stage sclerosing keratitits and iridocyclitis regressed, whilst advanced lesions of the anterior and posterior eye segment remained progressive. In conclusion, annual ivermectin treatments may prevent the emergence of ocular pathology in those populations still exposed to O.volvulus infection.
Trial Registration: www.pactr.orgPACTR201303000464219)

本研究针对23年间每年接受伊维菌素治疗的盘尾丝虫（Onchocerca volvulus）感染患者队列展开评估，旨在明确眼部病变的进展与转归。研究对象均居住于多哥中部农村及卡拉大区，眼科检查项目涵盖视力检测、眼前节裂隙灯检查，以及检眼镜眼底检查。
治疗前，82例患者中，52%的右眼、42%的左眼前房内可见活的盘尾丝虫微丝蚴（microfilariae, MF），24%的右眼、15%的左眼角膜内可见死亡微丝蚴。
初始治疗后23年（post initial treatment, PIT），82例患者均未在前房及角膜内检出微丝蚴。此时点状角膜炎（punctate keratitis, PK）病灶完全消退，未遗留可见角膜瘢痕（p<0.0001）；硬化性角膜炎（sclerosing keratitis, SK）病灶减轻一半，且该改善主要见于病程早期的患者。
早期虹膜睫状体炎的发生率从基线时的右眼42%、左眼40%，降至治疗后23年时双眼共13%（p<0.0001）；但与治疗前相比，治疗后23年时晚期虹膜睫状体炎的发生率升高（p<0.001）。
晚期视神经乳头炎与脉络膜视网膜炎未见消退；而基线时右眼28%、左眼27%的患者存在早期视神经乳头炎，至治疗后23年时分别降至17%和18%；基线时双眼共51%的患者存在早期脉络膜视网膜炎，至治疗后23年时右眼和左眼检出率分别仅为12%和13%（p<0.0001）。
综上，规律的年度伊维菌素治疗可清除并阻断盘尾丝虫微丝蚴侵入前房与角膜；点状角膜炎病灶完全消退，早期硬化性角膜炎及虹膜睫状体炎出现逆转，但眼前节与眼后节的晚期病灶仍呈进展态势。年度伊维菌素治疗可在仍暴露于盘尾丝虫感染的人群中预防眼部病变的发生。

试验注册：www.pactr.org PACTR201303000464219