Changes

*'''Spectacle''' - The embryologically-fused eyelids (hence no palpebral fissure) form a transparent covering of the eye called the spectacle (also known as the brille or eyecap).  Between the spectacle and the cornea are tear-like secretions.  The spectacle is [[Snake Shedding|shed]] during normal [[Ecdysis|ecdysis]] but may be pathologically retained (for example if [[Snake Mites|mites]] are present, with low humidity or if the eye is [[:Category:Snake Spectacular Diseases|diseased]]).  [[Snake Retained Spectacles|Retention of the spectacles]] has been associated with the development of corneal disease and panophthalmitis.

*'''Spectacle''' - The embryologically-fused eyelids (hence no palpebral fissure) form a transparent covering of the eye called the spectacle (also known as the brille or eyecap).  Between the spectacle and the cornea are tear-like secretions.  The spectacle is [[Snake Shedding|shed]] during normal [[Ecdysis|ecdysis]] but may be pathologically retained (for example if [[Snake Mites|mites]] are present, with low humidity or if the eye is [[:Category:Snake Spectacular Diseases|diseased]]).  [[Snake Retained Spectacles|Retention of the spectacles]] has been associated with the development of corneal disease and panophthalmitis.

*'''Tears''' - All reptiles produce tears.  In snakes, tears produce a region of lubrication between the cornea and the spectacle, allowing the free movement of the eye.  Paired nasolacrimal ducts drain the sub-spectacular spaces into the mouth near the vomeronasal organ.  Tears cannot overflow the eyelids, as in mammals, so if a nasolacrimal duct is damaged there is a build-up of tears under the spectacle, which leads to a [[Snake Bullous Spectaculopathy|bullous spectaculopathy]].

*'''Tears''' - All reptiles produce tears.  In snakes, tears produce a region of lubrication between the cornea and the spectacle, allowing the free movement of the eye.  Paired nasolacrimal ducts drain the sub-spectacular spaces into the mouth near the vomeronasal organ.  Tears cannot overflow the eyelids, as in mammals, so if a nasolacrimal duct is damaged there is a build-up of tears under the spectacle, which leads to a [[Snake Bullous Spectaculopathy|bullous spectaculopathy]].

*'''Cornea''' - The pupil is commonly elliptical or round and may give an indication of habitat and lifestyle.  Often diurnal species have round pupils and nocturnal species have vertical pupils.  [[coral snake|Coral snakes]] and all New World non-venomous snakes, except the [[Boa constrictor|boa constrictor]] have round pupils, while [[Pit Viper|pit vipers]] have vertical slit pupils.

*'''Cornea''' - The pupil is commonly elliptical or round and may give an indication of habitat and lifestyle.  Often diurnal species have round pupils and nocturnal species have vertical pupils.  [[coral snake|Coral snakes]] and all New World non-venomous snakes, except the [[Boa constrictor|boa constrictor]] have round pupils, while [[Pit viper|pit vipers]] have vertical slit pupils.

*'''Sclera''' - The eye has no ossicles (unlike other reptiles) and the sclera is composed entirely of tendinous connective tissue.

*'''Sclera''' - The eye has no ossicles (unlike other reptiles) and the sclera is composed entirely of tendinous connective tissue.

*'''Posterior segment''' - The retina is usually grey mottled with white or red spots and appears with semi-opaque nerve fibres radiating uniformly outwards from the optic disc that is obscured in families having a conus.  It is avascular and the membrana vasculosa retinae supply nutrients.

*'''Posterior segment''' - The retina is usually grey mottled with white or red spots and appears with semi-opaque nerve fibres radiating uniformly outwards from the optic disc that is obscured in families having a conus.  It is avascular and the membrana vasculosa retinae supply nutrients.