Note that there are several options to be worn over glasses, but that they MUST be ASTM 3077 approved. A pair of Recs-Spex designed for basketball would shatter with the impact of a lacrosse ball, so the ASTM 3077 designation is designed to protect from the high-speed impact of a lacrosse ball.
Each year we get questions on eye protection for girls with glasses. They are not readily available at local sporting goods stores we have found, so you may need to purchase online directly from the manufacturers or from Amazon. Again, please make sure that any eye protection you purchase meets the ASTM 3077 safety standard. Referees do an inspection prior to the start of each game, and will not permit unapproved eyewear from being worn.