HYDROGEL (SOFT) LENSES

Hydrogel lenses are made relatively large in diameter, usually 13.5 to 14.5 mm in diameter which results in the lens edge being beyond the limbus on the sclera.

It is necessary to use these 
large diameters to keep the 
lens centered and to provide 
comfort. Hydrogel lenses are 
comfortable due to being large 
in size rather than being soft.  
Most of the sensation from a 
contact lens is due to the 
eyelids hitting the edge of the 
lens, not from the cornea.

Since these lenses are soft and flexible, not as many back curve variations are required to fit a wider range of eye shapes as is required with rigid corneal lenses.