動体検知コントラスト閾値—POAGにおける新種の自覚的視機能異常

Contrast threshold for motion perception. A new parameter for screening of primary open angle glaucoma

　原発開放隅角緑内障（POAG）の早期の自覚的視機能異常として動体検知能力の低下を想定し，当科で考案した装置を用いて動体検知コントラスト閾値を視力良好（矯正視力≧0.8）なPOAG眼（24例42眼）および対照眼（23例42眼）で調べた。POAG群における動体検知コントラスト閾値の対数（−1.50±0.33）は，対照眼群におけるそれ（−2.15±0.30）よりも有意に高かった（P＜0.01,Student t—検定）。POAG群における動体検知コントラスト閾値の上昇の程度は視野狭窄の程度（湖崎分類Ⅰa〜Ⅲ）にかかわらなかった。本報結果は，動体検知コントラスト閾値の上昇がPOAGにおける自覚的視機能異常である可能性を示唆する。

We evaluated the value of contrast threshold for motion perception (CTMP) in 42 eyes with primary open angle glaucoma (POAG) and age-matched 42 control eyes. The CTMP purports to perceive oscil-laging vertical gratings against bright white back-ground of 850cd/m². The oscillation in shaped as a sinusoidal modulation at 4Hz and 0.6' stroke. The grating is of rectangular modulation at 1.8 cycle/ degree. All the 84 eyes had corrected visual acuityof 20/25 or better. The observed log CTMP value was independent of the age or the visual acuity in either group. The log CTMP value averaged -1.50±0.33 for POAG eyes and -2.15±0.30 for control eyes. These two values were significantly different (p＜0.01, Student t-test). The log CTMP value was elevated in POAG eyes regardless of the presence or extent of visual field defect. The find-ings suggest that CTMP can serve as a new param-eter for impairment visual function in POAG.