Trans 017 Neurooptha part 2 Flashcards
FUNCTIONS OF THE PUPIL
- Control in retinal illumination
- Reduction in optical aberration
- Depth of Focus
CLINICAL IMPORTANCE of the pupil
- Objective indicator of Light Input
- Anisocoria
- Pharmacological Indicator
- Indicated level of wakefulness
Direct light vs Consensual vs Near Reflex
DIRECT light reflex - Constriction of the pupil that was shined with light
✓ CONSENSUAL light reflex - Constriction of the other pupil without direct shining of light
✓ NEAR reflex - Constriction of the pupil without stimulation of light but when you focus at near objects
Two components of near reflex?
Convergence and Accomodation
Convergence of visual axis and associated constriction of pupil
When you’re looking at a far object and then suddenly you focus on the near object, your eyes will converge; this is accompanied by automatic constriction of pupil
Convergence reflex
Increased accommodation and associated constriction of pupil
Your lens will change in shape, especially hen you’re younger than 40 years old without the need for eyeglasses, they can see clearly at far and can see clearly at near, and that’s because of your accommodation; there is constriction of your ciliary muscles that will change the shape of your lens; part of this reflex is the constriction of pupil.
Accomodation reflex
Near Reflex Triad consists of:
o Increased Accommodation
Lens will change in shape to make it like a magnifying glass
o Convergence of Visual Axis
o Constriction of pupils
how to do the near reflex test?
- Instruct the patient to look at the distant target
- The examiner holds up a target containing fine detail approximately 25cm from the patient
- Ask the patient to fixate the near target and look for pupil constriction
- Note the speed of the constriction and the roundness of each pupil
AFFERENT PUPILLARY REFLEX is assessment of what to what?
Assessment of afferent input from the retina, optic nerve, and chiasm, optic tract and midbrain till LGB (Lateral Geniculate Body)
cause a reduction in pupil contraction when one eye is stimulated by light compared with when the opposite eye is stimulated by light.
may be associated with visual field or electroretinographic asymmetries between the two eyes
• Asymmetrical differences in retinal appearance or optic nerve appearance may occur
RAPD
Some causes of RAPD
- Optic neuritis
- Anterior ischemic optic neuropathy
- Compressive optic neuropathy
- Glaucoma
- Optic Nerve Tumors
- Orbital Diseases
- Ischemic Retinal Diseases: CRAO, CRVO, BRAO, BRAVO
- Ocular Ischemic Syndrome
- Central Serous Retinopathy or Crystoid Macular Edema
- Retinal Detachment
- Chiasmal Compression
- Optic Tract Lesion
- Post Geniculate Damage
- Midbrain tectal Damage
is defined by a difference in the size of the two pupils of 0.4 mm or greater.
Anisocoria
It should be considered a neurosurgical emergency if a patient has anisocoria with
acute onset of third-nerve palsy (“frozen eye”) and associated with headache or trauma.
If the difference in pupil size in both light and dark illumination is constant, then it is called
Physiologic or Essential anisocoria
DISORDERS CHARACTERIZED BY ANISOCORIA
- Horner’s syndrome
- Adie’s tonic syndrome
- Third-nerve palsy
- Adrenergic mydriasis
- Anticholinergic mydriasis
- Argyll Robertson pupils
- Local iris disease (e.g., sphincter atrophy, posterior synechiae, pseudoexofoliation syndrome)
- Hutchinson’s pupil
- Bernard’s syndrome
OCULOMOTOR NERVE PALSY WITH OR WITHOUT PUPIL INVOLVEMENT is a surgical emergency, true or false?
True