Ortho K lenses can be understood as lenses that you can wear overnight even during sleep. As you are asleep, these lenses gently reshape the front surface of your eye to correct it and can be removed when waking up so that you can see clearly during the day.
It can take from two weeks to two months, depending on the condition that’s being corrected. You will see a gradual improvement in vision each day as you keep using it. You might have to go through a series of temporary ortho K lenses before you reach your desired prescription. Once you find the correct prescription for ortho K lenses, you can use them for a longer time to maintain your routine correction.