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82 Cards in this Set

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  • Back
Mitotic activity occurs in which layer of the cornea?
basal layer of epithelium
T/F The epithelium plays a role in immunity
True--it is a physical barrier
What two layers of the cornea serve as barriers?
Endothelium & epithelium
A commonality of both corneal barriers is that they regulate entry of what substance into the stroma?
H2O
What is the first step in corneal wound healing?
mitosis ceases
What is the most common type of chemical burn?
Alkaline
What is an ocular finding after a chemical burn that indicates a poor prognosis?
neutrophiles are present
Name three components of the ocular surface.
Lipid, aqueous, mucin layer, or protein, water & lipids
Name one way a contact lens alters the ocular surface.
Reduces O2 permeability
Does a gas permeable lens or soft contact lens allow more tear exchange?
Gas Permeable Lens
Explain evaporative dry eye disease.
Deficient lipids, meibomian gland dysfunction
Describe aqueous deficient dry eye disease.
Hypertonic
What is the specific type of proprioceptive detector in the eye?
Palisade Endings
EOMs have large, medium, or small motor units.
Small
What are the major components of a motor unit?
Muscle fiber + neuron
What is one reason EOMs are fatigue-resistant?
light load, eye weighs very little
When giving botulinum injections for strabismus, how long is the effect expected to last?
Permanently
EOMs have unique properties that make them susceptible to which disease?
Myasthenia gravis
EOMs have a decrease or increased number of mitochondria compared to other types of skeletal muscle.
Increased
Chronic progressive external ophthalmoplegia is characteristic of which mitochondrial disorder?
mitochondrial myopathy --> Kararn sayers
What two ocular findings are consistent with CPEO?
Ptosis and inability to move eyes (mitochondria are ragged and red)
What is the reflective index of the aqueous?
1.3332
In general, is the production of the aqueous or the outflow of the aqueous more variable?
Outflow, constant (relatively) rate of production
Why are diffusion and ultrafiltration important in the production of aqueous (although they contribute minimally to overall aqueous production)?
They form a reservoir in the CBB
How does water travel into the posterior chamber?
Follows Na+ from stroma of NPCE
What reaction does carbonic anhydrase catalyze?
Formation of bicarbonate

carbonic
anhydrase
CO2 + H20 --------> HCO3- + H+
The Na-K-ATPase is found in the
NPCE
The Na-K-ATPase drives what ion into the posterior chamber?
Na+
How does sodium get into the NPCE?
Na+/H+ exchanger
Name the three locations that carbonic anhydrase is found in the body.
Kidney, brain and eyes
How is the composition of aqueous different from that of plasma?
1) Lower protein 2) High ascorbate
What are the two reasons why the aqueous differs in composition from the plasma?
1) Blood aqueous barrier 2) Active transport
Why is ascorbate beneficial?
protects from UV damage
How does Schlemm's canal contribute to the blood-aqueous barrier?
Continuous endothelial cells prevent back flow of aqueous
Name one factor that can disrupt that blood-aqueous barrier?
Surgery, trauma, inflammation, infection, drugs
Why is the blood-aqueous barrier important?
selects the movement of solutes
Which is higher--the pressure in the capillaries or the intraocular pressure?
capillaries
Which is higher--the pressure in the episcleral veins or the IOP?
IOP
Name two factors which can obstruct aqueous outflow
Neovascularization, inflammatory cells, hyphema, traumatic damage
Which class of glaucoma drugs are considered first-line therapy?
prostaglandins (enhance uvealscleral outflow + least side effects)
Why have topical CAIs fallen into disfavor (why are they not first-line therapy for glaucoma?)
Side effects including metallic taste and corneal swelling
Oxidative stress causes the generation of ________ that are damaging to the lens.
Free radicals (ROS)
What specific adaptation does the lens employ to minimize damage from oxidative stress?
It is a reducing structure
The highly layered structure of the lens poses what type of problem?
Decreased metabolism centrally
How do the proteins within the lens differ from other proteins within the body?
Proteins within the lens are the oldest
What effect does lactic acid have on the interior of the lens
Lowers pH (affects metabolism and enzymes)
Name two noteworthy things about NSC?
1) Most common 2) Myopic shift
Which area of the lens do cortical cataracts typically affect?
Inferior nasal
Anterior polar cataracts are usually congenital or age related?
Congenital
Oral steroids have the propensity to cause which type of cataract?
Posterior subcapular cataract (PSC)
What is a hypermature cataract called?
Morgagnian
Which enzyme is probably active in the formation of diabetic cataracts?
aldose reductase
What is the pathophysiology of posterior capsule opacification?
Damage from high glucose levels
Is the near triad an entity of which we have control?
No
What effect will the introduction of a -3.00 lens have on a person's visual system
Stimulate accommodation
According of Duane, on average a person loses ______ diopters of accommodation per decade
2.3 diopters/decade
Explain absolute presbyopia
Zero accommodation left
How many diopters of accommodation do we have in youth?
15 diopters
By age 50, most people have about _______ diopters of accommodation left.
1D left
What structure coordinates the actions of the near triad?
EW nucleus
Name the three functions of the pupil.
1) Depth of focus 2) Reduce aberrations 3) Controls retinal illumination
What is the range of pupil size (in log units)?
12 log units
Why is miosis sometimes beneficial in visual function?
Increases depth of focus
Why is pupil size a consideration in refractive surgery?
Large pupil can cause glare
If someone has advanced glaucoma in both eyes, will they have an APD?
No because it is relative to the other eye
You are studying for ocular physiology and someone drops a medical dictionary behind you, startling you. What is the effect on your pupil size?
Pupil gets bigger (sympathetic)
A patient is undergoing a liver transplant---you life the lid and notice the pupil is___
Anesthsia, miotic
What symptom would a patient with a fixed pupil potentially have?
Photophobia
You are living it up at Salty's and you notice someone with markedly dilated pupils. What is one possible cause?
Ecstasy, cocaine, heroine
What are direct and consensual responses equal in humans but not in rabbits?
Equal vs. varied innervation of pathways b/w brain and eyes
Why are pupils affected early on in aneurysms of the Circle of Wilis?
Most aneurysms affect te ICA, which supplies the Ophthalmic artery, which supplies the eye
The ciliary ganglion is most important in sympathetic or parasympathetic innervations
Parasympathetic
Which nerves supply the iris sphincter?
CN III (more specifically the short ciliary nerve)
Which muscle is strongest, the dilator or sphincter?
Sphincter
The second neuron in the sympathetic chain is considered pre- or post-ganclionic
Preganglionic
Where does the first neuron in the sympathetic chain synapse?
Lateral column of spinal cord (C7-T2)
Where does the second neuron in the sympathetic chain synapse?
Superior cervical ganglion
Which nerves supply the iris dilator?
Long ciliary nerves
Describe humoral influences
Elements of the blood
Which APD is more sever: a 0.3 log unit defect or a 3.0 defect?
3.0 log defect
If a patient has an interruption of parasympathetic flow, when will the defect be most noticeable?
During the day. --The pupil can't constrict!
What is the classic triad in Horner's syndrome?
Ptosis, miosis, anhidrosis