To prevent keratoconus which of the following is used

Keratoconus cannot be prevented by any measures. Its progression can be slowed down or it can be treated by following methods: Treatment. Falling vision may not be corrected by glasses due to irregular astigmatism.
Contact lenses (rigid gas permeable) usually improve the vision in early cases.
In later stages penetrating keratoplasty may be required.
Intacs, the intracorneal ring segments, are repoed to be useful in early cases. Generally, keratoconus cannot be prevented. Prevention: Regular and periodical eye tests for all family members above 10 years, mainly for families with keratoconus history and risk factors. Avoiding rubbing your eyes due to allergies. Following doctor's instructions and immediately repoing any noticeable progression. Ref: Parson; 21st edition; Pg no. 211