Refractive cornea In the eyes of most terrestrial vertebrates -LRB- along with spiders and some insect larvae -RRB- the vitreous fluid has a higher refractive index than the air , relieving the lens of the function of reducing the focal length .

Refractive cornea The eyes of most land-living vertebrates -LRB- as well as those of some spiders , and -LSB- -LSB- insect larvae -RRB- contain a fluid that has a higher refractive index than the air .
