Ah...the BCG's or Geekers... rarely seen in public after Plebe Summer. Sometimes show up in Cameo appearances for Company photos (they used to do a formal photo each year, and if time permits, a second spirit shot where almost anything goes). Don't worry Mom and Dad, fit of glasses is probably the least of DS/DD worries right now. And yes, if fit or Rx becomes a problem, Medical will take care of it ! I do recall seeing alot of Plebes with straps keeping BCG's in place.
Navy was always pretty good with eye wear. You can usually wear your own, as long as reasonable and within uniform regs. Upon graduation, aviators were ussyed one pair of regular, and one pair of Rx sunglasses a year. I recall I had more glasses than I knew what to do with, since my RX didn't change that much. I believe submariners had a similar deal, as they had special glasses to fit under their OBA.