Astigmatism is a refractive condition with a relatively predictable course throughout life. A high degree of astigmatism in infants and toddlers is common, but in most cases the cornea flattens and astigmatism lessens later in childhood. The degree of astigmatism usually stabilizes in adulthood, and there are typically small degrees of astigmatism, mostly of a with-the-rule (WTR) type. After 40 years of age, the cornea tends to steepen again, more in the horizontal than the vertical meridian, and so a shift toward against-the-rule (ATR) astigmatism is observed. 
Regular astigmatism in children
Prognosis is good in most of these cases, as the degree of astigmatism is gradually reduced throughout early childhood. However, it is important to detect those who remain with high degrees of astigmatism and to prescribe correction to decrease the risk of amblyopia. 
Regular astigmatism in adults
In adult patients, the degree of astigmatism is usually stable and good visual acuity can be achieved by optic correction. 
Keratoconus usually affects one eye first and then the other eye becomes affected within a few years. Consequently, the first eye affected tends to develop a more advanced corneal distortion. Predicting the rate of progression for an individual patient is impossible. Some patients experience alternating periods of fast progression and stabilization.  According to 1 large study of keratoconic patients, >20% of the patients required corneal grafting at an average of 8.8 years from the time of diagnosis. 
Infants and young children with a significant amount of astigmatism (>0.75 diopter) should be re-examined every 3 to 6 months until stability is achieved. Once children are able to speak, it is important to determine visual acuity in order to detect amblyopia as early as possible. Regular retinoscopy is mandatory to follow the degree of astigmatism and to modify the prescription as needed. Once stability is achieved, it is possible to schedule follow-up examinations less frequently depending on the patient's overall ophthalmic needs.
Parents of children with astigmatism should be informed about the importance of close follow-up during the first years of life to facilitate timely treatment and to reduce the risk of amblyopia. If astigmatic amblyopia is already present, it should be emphasized that wearing glasses at all times is crucial.