Mydriasis disorders e.g. epilepsy, stroke, and impending brain herniation are known to lead to temporal mydriasis as well. A brain catastrophe, or a rapidly increasing brain mass, can cause compression of the oculomotor nerve. In cases of head injury or orbit trauma (eye injury), the iris sphincter (the muscle responsible for closing the pupil) or the nerves controlling it can be damaged, reducing or eliminating the normal pupillary light reflex. A mydriatic is an agent that induces dilation of the pupil. Drugs such as tropicamide are used in medicine to permit examination of the retina and other deep structures of the
Normally hyperbolic invariant manifold the unstable bundle and denoted "E" and "E", respectively. With respect to some Riemannian metric on "M", the restriction of "Df" to "E" must be a contraction and the restriction of "Df" to "E" must be an expansion, and must be relatively neutral on formula_4. Thus, there exist constants formula_5 and "c" > 0 such that and Normally hyperbolic invariant manifold A normally hyperbolic invariant manifold (NHIM) is a natural generalization of a hyperbolic fixed point and a hyperbolic set. The difference can be described heuristically as follows: For a manifold formula_1 to be normally hyperbolic we are allowed to