Preferential looking法による極小未熟児の視力発達

Development of visual acuity in very low weight premature infants evaluated by preferential looking method

（1）2カ月齢から3歳までの乳幼児263例について，preferential looking （以下PL）法を用いて視力を測定した．

（2） PL法は乳幼児の視覚障害の早期発見のために，定量的視力評価法として優れた検査法であり，臨床面で広く用いられるべきである．

（3）片眼視力の測定が難しく正確なPL視力が測定できない症例に対しては，月齢に即した工夫によって更に成功率を向上させることが期待できる．

（4） PL法によって得られた極小未熟児および超未熟児の視覚発達の特徴は，出生直後からは視性刺激を受けても視力の発達を開始せず，出産予定日を3カ月過ぎた頃から早産分だけ遅れて発達する．出生後6カ月経過すれば，正常乳幼児と同様の発達を示す．

（5）極小未熟児および超未熟児の視覚発達は，出産予定日から考えることが妥当である．

A series of 263 infants, aged 2 months to 3 years, were evaluated as to the visual acuity by means of preferential looking method. This method was effective for the qualitative assessement of visual acuity in infants in the present series. The success rate was enhanced by improved handling of uncoop-erative infants.

Findings in 128 infants, who were born prema-ture with very low birthweight, indicated that visual acuity development does not start immediately at birth, but approximately at the third month after the expected date of birth. They usually reach the normal level of visual acuity 6 months after birth.