Although a properly fit scleral contact lens should fully vault the entire corneal surface, there are some severe cases that make this difficult to achieve. If there is touch of the lens to the cornea without bearing and the patient has no signs or symptoms of problems, than no other action is needed and the fit is considered acceptable. However, if this touch should cause the patient irritation and refitting is not an option, then a soft contact lens can be worn underneath the scleral lens to act as a cushion between the scleral lens and the cornea. The scleral lens is piggybacked onto the soft contact lens. One worry with wearing two lenses is that this combination will decrease the oxygen supply to the cornea, which can cause complications. However, modern gas-permeable scleral lenses and soft silicone hydrogel contact lenses are hyperpermeable and this is rarely a problem. A fluorescein photo shows a piggybacked scleral lens.
Piggybacking Scleral Lenses
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