Changes

[[Image:Panther_Chameleon.jpg|300px|thumb|right|'''Panther chameleon spectacle''' (© Tom Junek, Wikimedia Commons)]]

[[Image:Panther_Chameleon.jpg|300px|thumb|right|'''Panther chameleon spectacle''' (© Tom Junek, Wikimedia Commons)]]

[[Image:Lizard_skull_mandible.jpg|150px|thumb|right|'''Parietal eye on the dorsum of the head''' (Copyright © RVC)]]

[[Image:Lizard_skull_mandible.jpg|150px|thumb|right|'''Parietal eye on the dorsum of the head''' (Copyright © RVC)]]

Common [[Mydriatic|mydriatics]] have no effect on the reptilian eye because both the iris sphincter and ciliary muscle contain striated (or skeletal) rather than smooth muscle. This means that they are under conscious control. Therefore, unlike mammals, the consensual pupillary response is absent, the cornea does not contain a Descemets membrane and scleral ossicles are often present. This renders the ocular examination more challenging but more importantly, the parasympatholytic topical drugs (that reduce the activity of the parasympathetic nervous system) used to dilate the pupil ([[Mydriatic|mydriasis]]) in mammals are totally ineffective.

Common [[Mydriatic|mydriatics]] have no effect on the reptilian eye because both the iris sphincter and ciliary muscle contain striated (or skeletal) rather than smooth muscle. This means that they are under conscious control. Therefore, unlike mammals, the consensual pupillary response is absent, the cornea does not contain a Descemets membrane and scleral ossicles are often present. This renders the ocular examination more challenging but more importantly, the parasympatholytic topical drugs (that reduce the activity of the parasympathetic nervous system) used to dilate the pupil ([[Mydriatic|mydriasis]]) in mammals are totally ineffective.