走査型レーザー検眼鏡による眼底の観察

Observation of the ocular fundus with scanning laser ophthalmoscope

　走査型レーザー検眼鏡（SLO）を用いて，各種眼底疾患のある393眼の眼底を観察記録した。光源としてアルゴンとヘリウムネオンの2種類のレーザーを用い，解像力，波長特性，焦点深度について，従来の眼底カメラによる画像と比較した。網膜血管については，SLOは，従来の眼底カメラに近い解像力が得られた。また，モニタ画面の動画に比べ，静止画では解像力の低下が言立った。アルゴンレーザー青（488nm）では，神経線維など網膜表面の変化について良好なコントラストが得られた。黄斑前膜や網膜雛襞など，眼底カメラではとらえにくい変化を観察できた。ヘリウムネオンレーザー（633nm）では，網膜深層から脈絡膜にかけての深層の画像が強調されて観察できた。SLOの焦点深度は深く，網膜表面に焦点を合わせたままで硝子体混濁の観察が可能であった。観察および撮影光量が少なく，被検者の羞明感は少なかった。SLOは，眼底カメラに近い解像力が得られ，波長に応じて眼底の表層や深層が強調されるだけでなく，網膜表層や硝子体など，従来の眼底カメラではとらえにくい部位の観察記録が可能であり，焦点深度が深く，眼底の観察に有用な検査法であると評価された。

We observed the ocular fundus of 393 eyes with various vitreoretinal disorders using a scanning laser ophthalmoscope (SLO, Rodenstock). We used either of 3 wavelengths: argon laser at 488 or 514 nm, or helium-neon laser at 633nm. Following conclusions were obtained by comaring the record-ed fundus image by SLO with that by conventional fundus camera. The resolution power of SLO was comparable to that of the fundus camera when seen on the video screen. The quality deteriorated signif-icantly when seen as a print-out. The surface struc-ture of the retina appeared more contrast-rich and enhanced when seen by argon laser. Premacular membranes or surface wrinkles were thus moresharply recorded by SLO than by conventional camera. When the fundus was scanned by helium -neon laser, the structure of deeper layers of the retina or the choroid became more clearly visible. SLO facilitated simultaneous focusing of the retina and vitreous opacities because of inherent deeper range of focus. Fundus examination and recording by SLO induced notable decrease in glare due to far lesser intensity of illuminating laser light. We con-clude that SLO is superior to conventional fundus photography as SLO enhances the visibility of spe-cific layers of the ocular fundus by using laser beam of different wavelengths and as it allows clear imaging of the vitreous opacity or pathological retinal surface. SLO thus promises to be a useful tool in the investigation of fundus disorders.