The brille is the layer of transparent, immovable disc-shaped skin or scale covering the eyes of some animals for protection, especially in animals without eyelids. The brille has evolved from a fusion of the upper and lower eyelids. Brille is German and Norwegian for "glasses

Glasses

Glasses, also known as eyeglasses , spectacles or simply specs , are frames bearing lenses worn in front of the eyes. They are normally used for vision correction or eye protection. Safety glasses are a kind of eye protection against flying debris or against visible and near visible light or...

".

In snakes, there is no eyelid and the brille is clear and cannot be distinguished except when the animal is becoming ready for ecdysis

Ecdysis

Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...

. At that time, it becomes cloudy and is visible as a cover over the eye. When the snake moults, the brille is also shed as part of its skin. The Brilles protect their eyes from dust and dirt and gives them a "glassy-eyed" blank appearance.

Snake

Snake

Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

s, flap-footed lizards, night lizard

Night lizard

Night lizards are a group of very small, viviparous lizards, averaging from less than 4 cm to over 12 cm long. The family has only three genera, with approximately 23 living species...

s, and some skink

Skink

Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...

s have brilles. All gecko

Gecko

Geckos are lizards belonging to the infraorder Gekkota, found in warm climates throughout the world. They range from 1.6 cm to 60 cm....

s except those in the subfamily Eublepharinae

Eublepharinae

Eublepharinae is one of five subfamilies of the Gekkonidae, or geckos. Eublepharinae has 27 species in five genera. Also called eyelid geckos, the Eublepharines have more primitive features than other geckos. In particular, their feet lack the modifications that allow most other geckos to climb...

 (eyelid geckos) possess brilles.

Fish also have transparent eyelids called adipose eyelids.