初期糖尿病性網膜症における血液網膜柵の検討

State of blood-retinal barrier in early stage diabetic eyes

　網膜症発症前と初期網膜症を有する糖尿病患者の血液網膜柵内方透過係数（Pin）と硝子体内拡散係数（D）を検討した。PinとD値は，Fluorescein-Na静注後のvitreous fluoro-photometry値と血漿free fluorescein値よりcomputer simulation法を用いて算出した。正常群のPinおよびD値は20歳代から40歳代にかけてほぼ一定だが，50歳代以後に増大した。それゆえ，正常眼では50歳代より，血液網膜柵の機能異常や硝子体性状の変化が生じるものと推測された。網膜症を有さない糖尿病患者A群のPinおよびD値は，各年代ごとに正常群と比較するといずれの年代でも有意差はなかった。A群の症例をHbA_1c値と罹病期間をもとに細分してPin値を検討すると，60歳代でHbA_1c値が高く，また罹病期間が長い症例では，正常群とくらべ，Pin値は増大していた。Cunha-Vazらは，網膜症のみられる前より，血液網膜柵の破壊がみられると報告しているが，正常群と年齢をmatchさせて比較しただけでは，そのような所見は，観察されなかった。しかし，60歳代でHbA_1c値が高く，罹病期間が長い糖尿病患者と正常群とを比較すると，彼らの知見と合致した。

We performed vitreous fluorophotometry in 90 eyes of 52 diabetic subjects and in 43 eyes of 23 healthy persons. In the diabetic patients, no appar-ent retinopathy was present in 36 eyes. Capillary microaneurysms were the cardinal features in 36 eyes. Additional retinal hemorrhagic patches were present in 18 eyes. We determined the inward per-meability of the blood-retinal barrier (pin) and diffusion coefficient in the vitreous (D).

In the normal group, the Pin and D valuesremained stationary throughout the 3rd to 5th decade of age and increased in their 6th and 7th. There was no significant difference in the values, when matched for age, between diabetic patients without apparent retinopathy and normal subjects. The Pin value was significantly elevated in diabetic patients without apparent retinal involvement when the patients were in their 7th decade, the HbA_1c value was higher than 7%, and when the duration of diabetes was more than 5 years.

The Pin and D values were consistently higher in diabetic patients with retinopathy than normal controls.