多局所網膜電図における2次核成分の緑内障への応用の検討

Second-order component of multifocal electroretinogram in eyes with glaucoma

要約　目的：緑内障眼での多局所網膜電図の特徴と，網膜神経線維厚ならびにHumphrey視野との関係の報告。対象と方法：原発開放隅角緑内障22例31眼を対象とした。全例で矯正視力が0.5以上であり，多局所網膜電図，Humphrey視野，光干渉断層計（OCT）により検索した。多局所網膜電図については，中心窩から5°の距離での2次核成分のN/T比を鼻側と耳側視野とで算出し，視野とOCTによる所見と比較した。緑内障のない30眼で同様の検査を行い，対照とした。結果：緑内障眼と非緑内障眼とは，N/T比を0.563に設定することで，最も効率良く分離でき，74.2％の感度と90.0％の特異性が得られた。多局所網膜電図の2次核成分振幅のN/T比は，視野のパラメータと相関があり，網膜神経線維厚とには有意の相関がなかった。結論：多局所網膜電図の2次核成分振幅のN/T比は，緑内障による網膜障害の指標として有用である可能性がある。

Abstract.　Purpose：To report characteristics of second-order component of multifocal electroretinogram（mfERG）and relation between mfERG and retinal nerve fiber layer thickness and visual field examination in eyes with glaucoma. Cases and Method：This study was made on 31 eyes of 22 patients with primary open-angle glaucoma. All the eyes had visual acuity of 0.5 or better. They were tested regarding mfERG, visual field by Humphrey Field Analyzer, and optical coherence tomography. Amplitudes of second-order kernel responses of mfERG were evaluated in the nasal and temporal hemisphere within 5 degrees from the fovea and ratio of nasal and temporal amplitudes were calculated as N/T amplitude ratio. Findings were compared with visual field and those by OCT. Another series of 30 normal persons served as control. Results：Eyes with and without glaucoma could be best differentiated by setting the N/T amplitude ratio at 0.563, showing sensitivity of 74.2％ and specificity of 90.0％. N/T amplitude ratio of second-order kernel responses of mfERG were significantly correlated with parameters of visual field and not with retinal nerve fiber thickness. Conclusion：N/T ratio of second-order kernel responses of mfERG promises to be useful in detecting glaucomatous retinal lesion.