Anatomy and Physiology XXVIII Flashcards
What results from retinal detachment?
Degeneration of photoreceptors cause vision loss (p.441)
To what causes may retinal detachment be a secondary consequence?
Retina breaks (surgical emergency), diabetic traction, inflammatory effusions (p.441)
What types of patients are most prone to retinal breaks?
Patients with high myopia (p.441)
What condition typically proceeds retinal breaks?
Posterior vitreous detatchment (flashes and floaters) and eventual monocular loss of vision (p.441)
What is the macula?
The central area of the retina (p.441)
What symptoms are caused by age related macular degeneration?
Distortion (metamorphopsia) and eventual loss of central vision (scotomas) (p.441)
What is dry macular degeneration?
Nonexudative macular degeneration with deposition of yellowish extracellular material beneath retinal pigment epithelium with a gradual decrease in vision (p.441)
What is wet macular degeneration?
Exudative macular degeneration with rapid loss of vision due to bleeding secondary to choroidal neovascularization (p.441)
Is wet or dry macular degeneration more common?
Dry (nonexudative) > 80% (p.441)
How is progression of dry macular degeneration prevented?
Multivitamin and antioxidant supplements (p.441)
How is wet macular degeneration treated?
Anti-VEGF injections or laser treatment (p.441)
What is anopia?
Complete loss of vision in an eye (p.441)
What is hemianopia?
Loss of half of a visual field (p.441)
A lesion in what location would cause left upper quadrantic anopia?
In the right Meyer’s loop of the temporal lobe; MCA infarct (p.441)
A lesion in what location would cause left lower quadrantic anopia?
In the right dorsal optic radiation of the parietal lobe; MCA infarct (p.441)
What is a scotoma?
Loss of central vision (p.441)
Where is Meyer’s loop?
The inferior retina; it loops around the inferior horn of the lateral ventricle (p.441)
Where is the Dorsal Optic Radiation?
The superior retina; it takes the shortest path via the internal capsule (p.441)
In what orientation is an image as it hits the primary visual cortex?
Upside down and left-right reversed (p.441)
What is the medial longitudinal fasciculus (MLF)?
A highly myelinated pair of tracts that allows for crosstalk between CN VI and CN III nuclei; it coordinates both eyes to move in the same horizonal direction (p.442)
In what types of conditions are lesions to the MLF most common?
Demyelinating conditions (ex. MS) (p.442)
What are lesions to the MLF called?
Internuclear opthalmoplegia (INO) (p.442)
Describe the clinical findings associated with internuclear opthalmoplegia.
Lack of communication between the eyes such that when CN VI nucleus activates the ispilateral lateral rectus, the contralateral CN III nucleus does not stimulate the medial rectus to fire. Abducting eyes have nystagmus (CN VI overfires to stimulate CN III) but convergence is normal (p.442)
Describe the coordination between CN III and CN IV in horizontal gaze.
When looking to the left, CN VI fires, contracting the left lateral rectus and stimulating the contralateral (right) nucleus of CN III via the right MLF to contract the right medial rectus (p.442)
