低眼圧緑内障の長期視野変化，定義および概念

Concept and definition of longterm visual field changes in low-tension glaucoma

　低眼圧緑内障における長期視野変化を検討する目的で32眼を平均4.6年間経過観察した．低眼圧緑内障の視野異常は非常に緩徐であり，32眼中進行性を示したのは7眼のみであり，湖崎分類で2期以上の進行性を認めたものはなかった．緑内障に特徴的な視野異常を示さなかったものは3眼であった．低眼圧緑内障の視野異常の緩徐な進行性は高眼圧緑内障との病態の相違を示すと考えられる．低眼圧緑内障とされる疾患は，（1）健常眼圧の低下，（2）高眼圧の看過，（3）虚血性視神経障害など偽緑内障を含み，低眼圧緑内障を研究するうえでこれらの疾患群を同一視することは混乱を招く．

We evaluated the course of visual field defects in 32 eyes with low-tension glaucoma. The follow-up period averaged 4.6 years. The visual field defects were sta-tionary in the majority of cases. Only 7 eyes showed progression of field loss by one stage after the classifi-cation by Kosaki. Three eyes manifested visual field defects untypical for glaucoma.

The observed differences in the characteristics of visual field between low-tension glaucoma and overt, hypertensive glaucoma may be attributed to inappropri-ate criteria for low-tension glaucoma. The so-called low-tension glaucoma include 3 different entities : 1 ) true low-tension glaucoma in which the visual, field deteriorates in spite of normal intraocular pressure level. 2) Hidden or silent glaucoma due to intermittent or previous elevation of intraocular pressure. 3 ) Pseudoglaucoma, including ischemic optic neuropathy. We propose that ischemic optic neuropathy be separ-ated from glaucoma. Patients with abnormal outflow facility are to be included in another category as they have episodes of elevated intraocular pressure. A rigid criterion is essential for the proper interpretation and clinical management of low-tension glaucoma.

Rinsho Ganka (Jpn J Clin Ophthalmol) 40(7) : 803-807, 1986