Objective:To elucidate long-term o utcome of trabeculoto-my in primary and secondary developm ental glaucoma.Methods:One hundred forty-nine eyes of 89patients with developmental glaucoma who underwe nt trabeculotomy were retrospectively studied.Intraocu lar pressure(IOP),suc-cess probabilities,visual acuitie s,and visual field were determined during follow-up and at t he final visit.Results:The mean ±SD IOP of 112eyes with prima ry develop-mental glaucoma at the final visit wi th an mean ±SD fol-low-up period of 9.5±7.1years was 15.6±5.0mm Hg.The average IOP for 37eyes with secon dary developmental glaucoma was 16.7±4.2mm Hg.One hundred eyes(89.3%)with primary developmental glaucom a were de-fined as achieving success at the fin al visit.Complete and qualified successes were achieved i n 71eyes(63.4%)and 29eyes(25.9%),respectively.Visual acuities were20/40or better in 78(59.5%)of 131eyes examined and were poorer than 20/200in 32eyes(24.4%).The causes of poor visual acuities were mainly progression of glaucoma,including delay of detection of onset or surgery and amblyopia.Eyes with glaucoma th at existed before 2months of age or eyes that needed seve ral trabeculotomies were considered to have poor visual a cuity.Visual fields were classified as normal or almost normal in 21(44.7%)of 47eyes.Conclusions:Trabeculotomy for developmental glaucoma is effective over a long tim e.There is a fairlygood prognosis for visual function o f eyes with develop-mental glaucoma with early detectio n of the onset,proper treatment,and proper management after trabeculotomy. Objective: To elucidate long-term o utcome of trabeculoto-my in primary and secondary developm ental glaucoma. Methods: One hundred forty-nine eyes of 89patients with developmental glaucoma who underwe nt trabeculotomy were retrospectively studied. Intraocu lar pressure (IOP), suc -cess probabilities, visual acuities, visual field were determined during follow-up and at final visit. Results: The mean ± SD IOP of 112 subjects with prima ry develop-mental glaucoma at the final visit wi th an mean ± SD fol-low-up period of 9.5 ± 7.1years was 15.6 ± 5.0mm Hg. The average IOP for 37eyes with secon dary developmental glaucoma was 16.7 ± 4.2mm Hg. One hundred eyes (89.3%) with primary developmental glaucom a were de- fined as achieving success at the fin al visit. Complete and qualified successes were achieved in 71yes (63.4%) and 29yes (25.9%), respectively. Visual acuities were 20 / 40or better in 78 (59.5%) of 131eyes examined and were poorer than 20 / 200in 32eyes (24.4%). The causes of poor visual acuities were m ainly progression of glaucoma, including delay of detection of onset or surgery and amblyopia. Eyes with glaucoma th at ever before 2months of age or eyes that needed severely trabeculotomies were considered to have poor visual a cuity .Visual fields were classified as normal or almost Normal in 21 (44.7%) of 47eyes. Conclusions: Trabeculotomy for developmental glaucoma is effective over a long tim e. There is a fairly good prognosis for visual function of eyes with develop-mental glaucoma with early detectio n of the onset, proper treatment, and proper management after trabeculotomy.