白内障手術後に近見作業困難を呈した強度・病的近視患者へのロービジョンケアの1例

A case of low vision care for a patient with severe/pathological myopia who had difficulties working near vision after cataract surgery

要約　目的：白内障手術後の屈折値変化により近見作業困難を呈した強度・病的近視患者に対するロービジョンケアについての報告。

症例：80代，男性。強度・病的近視。裸眼での接近視で読み書きをする習慣があった。他院での白内障手術後，術前に裸眼での接近視や拡大鏡（24D）の併用で可能であった読み書きに困難を訴え，国立障害者リハビリテーションセンター病院を受診した。術前の矯正視力は左右ともに0.01，術後は右0.04左0.03であった。屈折値は等価球面値で，術前右−20.00D，左−18.25Dから術後 右−0.75D，左−0.375Dへ変化し，術前のように接近視が可能な眼鏡の処方を強く希望された。強度近視で得られていた最大視認力をハイパワープラスレンズ眼鏡で再現するためには高加入が必要であったが，高加入では作業距離が短く，書字困難と読書時の疲労を示した。そこで，高拡大が可能な拡大読書器を紹介したが，接近視の希望が強く，選定に難渋した。複数回の試行で両眼＋11.25Dのハイパワープラスレンズ眼鏡を処方し，近見作業困難が改善した。この症例から，白内障手術後に視力の大幅な改善が困難な強度・病的近視症例では，術後屈折値が正視付近となると，接近視ができないという視環境の変化から見えにくさを訴えることが示された。また，強度近視で得られていた最大視認力を，術後に眼鏡によって再現するには限界があることがわかった。

結論：術後もロービジョンとなる可能性のある強度・病的近視症例の白内障手術では，術前の最大視認力を考慮した近視を残した術後屈折値の選択が必要なことが示唆された。

Abstract　Purpose：A report on low vision care for patients with severe/pathological myopia who had difficulty in working on object in close-proximity due to changes in refractive value after cataract surgery.

Case：The patient is a man in his 80 s, with severe/pathological myopia. He used to read and write unaided with the object of interest held at close-proximity. However, after cataract surgery at another hospital, he complained of difficulty in unaided reading and writing, as well as using a hand magnifier（24D）and visited our hospital. Preoperative corrected visual acuity was 0.01 in both eyes, and postoperative corrected visual acuity in the right and left eye were 0.04 and 0.03 respectively. The preoperative refraction value changed from −20.00D and −18.25D in equivalent spherical value to −0.75D and −0.375D after surgery. In order to obtain the maximum near vision possible with high myopia using high power plus glasses, high addition was necessary. However the working distance was short with high addition, and it led to eye fatigue when reading and writing. Therefore, we introduced a closed-circuit television capable of high magnification, but there was a strong desire for close-up vision, leading to difficulty in choosing. After multiple trials, the prescription of binocular ＋11.25D high power plus lens glasses improved the difficulty in near vision work. The present case study shows that patients with severe/pathological myopia, in whom it is difficult to significantly improve visual acuity after cataract surgery, may complain of difficulty in vision due to changes in the visual environment, such as being unable to see close-up when the postoperative refraction value is close to emmetropia. In addition, it was found that there is a limit to the reproducibility of the maximum near vision obtained by high myopia with spectacles after surgery.

Conclusion：In cataract surgery for patients with severe/pathological myopia, who may have low vision even after cataract surgery, it is suggested that a postoperative refractive value that preserves myopia considering the maximum near vision after surgery should be selected.