未熟児における屈折および角膜曲率半径の長期的変化と強度近視の考察

Longitudinal changes in refraction and corneal curvature in premature infants

要約　目的：未熟児の屈折と角膜曲率半径に成長と光凝固が及ぼす影響の報告。対象と方法：2009年1月までに生まれた低出生体重児155例310眼を，最低0週から最長8年まで観察した。在胎期間は160眼が22～26週，150眼が27～34週までであった。6歳時での屈折が－5D以上の強度近視が18例29眼であった。結果：屈折は修正21か月まで近視化し，角膜曲率半径は9か月まで増加した。在胎期間は屈折に影響せず，光凝固眼では非光凝固眼よりも有意に近視化した。光凝固の既往は角膜曲率半径に影響せず，在胎期間が短い非光凝固眼では曲率半径が有意に小さかった（Tukey-Kramer法，p＜0.01）。強度近視眼での角膜曲率半径は他の群と差がなかった。結論：未熟児の屈折は修正21か月まで近視化し，以後6歳までは変化が小さい。角膜曲率半径は修正9か月まで扁平化し，以後は変化が小さい。在胎期間は屈折に影響せず，光凝固の既往があると近視化する。光凝固の既往は角膜曲率半径に影響せず，在胎期間が短い非光凝固眼では曲率半径が小さい。

Abstract.　Purpose：To report changes in refraction and corneal curvature in premature infants treated with or without photocoagulation. Cases and Method：This study was made on 310 eyes of 155 premature infants born during 8 years through January 2009. The gestational age ranged from 22 to 26 weeks in 80 infants and from 27 to 34 weeks in 75 infants. High myopia of －5 diopters or over was present in 29 eyes of 18 children at 6 years of age. Results：Refraction tended towards myopia until adjusted age of 21 months. Radius of corneal curvature increased until 9 months of age. Refraction was independent of duration of gestation. Eyes treated by photocoagulation became significantly more myopic than the rest. Eyes with shorter gestational age and no history of photocoagulation showed smaller radius of corneal curvature than the rest（Tukey-Kramer test,p＜0.01）. There was no difference in corneal curvature between eyes with or without high myopia. Conclusion：Radius of corneal curvature was smaller in eyes with lower gestational age or with high myopia. It became stabilized at adjusted age of 9 months. Photocoagulation affected the incidence of myopia but not corneal curvature.