Cylindrical eye sight means astigmatism
, where the parallel rays of light from infinity will not come to point focus on the retina
Astigmatism is fairly common refractive error
seen in children accounting for about 20-30% of refractive errors in children.
Astigmatism is caused by either corneal causes where cornea is oval as you have mentioned or by lens
causes. The refractive error will become stabilized once the growth of the eye ball stops by about 18-20 years.
It is unlikely that cornea can become circular again and all the astigmatism is corrected by itself, hence as of now your kid has to use corrective glasses regularly and have to get eye power
check up once in 6 months or 1 year as the power keeps on varying in this growing age.