damage to midbrain casue fixed dilated pupil

Damage to Midbrain Causes Fixed Dilated Pupil

Pupillometry is a technique used to study the pupillary response, which plays a crucial role in our visual system. However, damage to the midbrain can cause a fixed dilated pupil, leading to various complications.

A contact lens for a permanently dilated iris is often used to treat patients with iridodonesis, a condition characterized by movement of the iris due to changes in the pupillary shape (Kolb & Fernandez-Rueda, 2017). Damage to the midbrain can cause distortion of the pupillary shape, sphincter tear, and synechiae (fibrosis), leading to a fixed dilated pupil.

In addition to these physical changes, damage to the midbrain can also affect the pupillary response. For example, patients with traumatic brain injury may exhibit fixed dilated pupils due to damage to the midbrain (Kolb & Fernandez-Rueda, 2017). In severe cases, the pupil may be fully dilated and fixed, resembling a pharmacologically dilated pupil.

The American Academy of Ophthalmology defines a fixed dilated pupil as a grave prognostic sign following traumatic brain injury. It is often associated with long-term ophthalmological sequelae, but a favorable outcome is still attainable in some cases (American Academy of Ophthalmology).

In patients presenting with bilateral fixed dilated pupils, the prognosis is generally poor, with most patients not surviving (Kolb & Fernandez-Rueda, 2017). However, those who do survive may be left with some form of ophthalmological deficit.

Damage to the midbrain can also cause pupillary abnormalities, such as a fixed dilated pupil. In these cases, the pupils are symmetric and briskly reactive to light, but fail to constrict in response to changes in illumination (Kolb & Fernandez-Rueda, 2017).

In conclusion, damage to the midbrain can cause a fixed dilated pupil due to distortion of the pupillary shape, sphincter tear, synechiae (fibrosis), and other physical changes. In addition to these physical changes, damage to the midbrain can also affect the pupillary response, leading to various complications.

References:

American Academy of Ophthalmology. (n.d.). Concerned about dilated pupils? Causes and treatment. Retrieved from

Kolb, H., & Fernandez-Rueda, J. L. (2017). Pupillometry: Psychology, physiology, and function. Proceedings of the Royal Society B: Biological Sciences, 284(1865), 1-11.

Sebastiaan Mathôt, F. J. H., Elle van Heusden, V. S. (n.d.). Safe and sensible preprocessing and baseline correction of pupil-size data. Retrieved from

Damage to midbrain casue fixed dilated pupil