Grant-in-Aid for General Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||Gifu University|
KITAZAWA Yoshiaki Gifu Univ. Sch. of Med., Professor, 医学部, 教授 (20009484)
SOGANO Shigeyo Gifu Univ. Sch. of Med., Instructor, 医学部附属病院, 助手 (00236150)
SUGIYAMA Kazuhisa Gifu Univ. Sch. of Med., Instructor, 医学部, 助手 (80179168)
ENYA Takio Gifu Univ. Sch. of Med., Instructor, 医学部附属病院, 助手 (60168763)
YAMAMOTO Tetsuya Gifu Univ. Sch. of Med., Assistant Professor, 医学部附属病院, 講師 (50134581)
JIKIHARA Shuich Gifu Univ. Sch. of Med., Associate Professor, 医学部, 助教授 (50115408)
清水 梅次 岐阜大学, 医学部・附属病院, 助手 (70226231)
富田 剛司 岐阜大学, 医学部・附属病院, 講師 (30172191)
松原 恵子 岐阜大学, 医学部, 助手 (10199838)
河合 憲司 岐阜大学, 医学部・附属病院, 助手 (00169666)
舩橋 正員 岐阜大学, 医学部, 助教授 (30112709)
|Project Period (FY)
1990 – 1992
Completed(Fiscal Year 1992)
|Budget Amount *help
¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 1992 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1991 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1990 : ¥800,000 (Direct Cost : ¥800,000)
|Keywords||Low-tension glaucoma / Optic disc / Image analysis / Differential light sensitivity / Retinal nerve fiber thickness / Trabeculectomy / Mitomycin C / Endothelin-I / 網膜神経線維層 / 軸索 / 視神経乳頭画像解析 / 視神経乳頭陥凹 / 実験的緑内障 / 虚血性ショック / 眼圧|
1. Topographic changes of the optic disc in low-tension glaucoma
1) Optic Nerve Head Analyzer Plus was evaluated for its accuracy and reporducibility in monkey eyes (Macaca fuscata), the latter was found to be around 5%. The accaracy was evaluated by comparing the in vivo measurements with those obtained in vitro, and was demonstrated to be adequate for the analyses of consecuitive disc images acquired over time.
2) There exists a considerable overlap of the topographic parameters between the normal and low tension glaucoma eyes. Hence, in collaboration with Dr. J. Caprioli, Yale University, a software program was developed to measure the height of the retinal nerve fiber layer and was used to analyze the data obtained by Optic Nerve Head Analyzer Plus.
3) By means of the program mentioned in 2), the retinal nerve fiber layer thickness was measured in low tension glaucoma patients with the disc damage of various severity. It was demonstrated that in the vast majority of low-tension glauco
ma eyes the retinal nerve fiber layer loses axons in some limited area, mostly inferior or superior temporal region nearby the disc, with the progress of the disease, the localized axonal loss tends to spread and at the same time new region with atennuated axons develop.
4) The tographic changes of the optic disc are correlated with the decrease of the differential light sensitivity in the retinal region which corresponds to the specific region of the disc. Among different topographic changes, the neuro-retinal rim was noted to best reflect the retinal, axonal loss.
5) In low-tension glaucoma eyes the reduction of intraocular pressure to low teens was made possible through means of mitomycin C, an antiproliferative agent. The persistent reduction brought about the improvement of differential light sensitivity threshold along with the partial reversal of optic disc changes.
2. The production of experimetally induced low-tension glaucoma in animals
The venous infusion of Na^+ or K^+ induced a discernible constriction of retinal vessels in rabbits without changes of optic disc. Intravitreal injection of endothelin I constricted retinal vessels markedly at a concentration of 10^<-7> mol (10 mu l). The injection of higher concentration (10^<-5> mol, 10 mu l) brought about long lasting vascular constriction resulting in the optic nerve atrophy.
The pretreatment with Ca^<2+>-channel blocker of rabbits diminished the vascular constriction in a dose-dependent manner. Less