急激な視野異常進行がみられた緑内障眼に合併した視神経乳頭周囲網膜分離症の4例

Four cases of peripapillary retinoschisis associated with glaucomatous eyes with rapid visual field abnormality progression

要約　目的：緑内障眼に合併する視神経乳頭周囲網膜分離症（PRS）は，乳頭付近の構造異常や脆弱性がその病態に関連するとされているが，PRS発症後の視野進行に関して一定の見解が得られていない。今回，PRS発症後に急激な視野異常進行がみられた4例について報告する。

症例：当院で両眼緑内障にて経過観察中の4例（すべて女性）に片眼のPRSを認めた。症例の内訳は，平均年齢63歳，平均屈折値−0.37D，平均眼軸長24.2mm，PRS発症後の平均観察期間33.5か月，視力1.0以上であった。PRSの局在は，全例乳頭耳下側の網膜神経線維層欠損に一致した網膜内層と外層分離を認め，黄斑剝離は伴っていなかった。PRS発症前・発症時・発症後の平均眼圧は，それぞれ12.4mmHg・13.2mmHg・12.7mmHgであった。PRS発症前後の視野結果は，発症直近の平均MD・PSD・VFI・患側に対応する上半TDは，それぞれ−4.41dB・7.82dB・90.7％・−3.31dB，発症後最終受診時は−6.07dB・10.05dB・76.0％・−9.15dBであり，全例で視野進行を認めた。また，PRS発症前の平均PSD slopeが0.66dBに対し発症後2.25dBであり，局所視野進行が示唆され，中心視野進行を全例に認めた。一方，同時期の経過期間中に僚眼の視野進行はみられなかった。

考按：緑内障眼に合併するPRS症例は，明らかに視野進行がみられる症例が存在する。特に乳頭黄斑線維束にPRSを生じた場合，急激な中心視野進行を伴う症例があり，早めの治療アプローチを考慮する必要性が考えられた。

Abstract　Purpose：Peripapillary retinoschisis（PRS）, which is a complication of glaucoma, is thought to be caused by structural abnormalities and fragility in the papillary area. In this report, we describe four cases of rapid visual field progression after the onset of PRS.

Cases：Four patients with PRS in one eye who were receiving eye drops for glaucoma in our hospital were found to have PRS in the other eye. The mean age was 63 years, the mean refraction was −0.37 D, the mean axial length was 24.2 mm, the mean observation period after the onset of PRS was 33.5 months, and visual acuity was 1.0 or better. The mean IOP before, at, and after the onset of PRS was 12.4 mmHg, 13.2 mmHg, and 12.7 mmHg, respectively The visual field results before and at the last visit after the onset of PRS showed that the mean MD, PSD, VFI, and upper half TD corresponding to the lesion side were −4.41 dB, 7.82 dB, 90.7％, and −3.31 dB, and −6.07 dB, 10.05 dB, 76.0％, and −9.15 dB respecctively, indicating visual field progression in all patients. The mean PSD slope before the onset of PRS was 0.66 dB, and after the oneset of PRS was 2.25 dB, suggesting regional visual field progression all patients had central visual field progression. However, there was no visual field progression in the bilateral eyes during the same period of time.

Discussion：There are cases of PRS associated with glaucomatous eyes that clearly show visual field progression. In particular, when PRS occurs in the papillomacular bundle, there are cases of central visual field progression, and it is necessary to consider an early treatment approach.