Lecture 10 2/20/25 Flashcards
What are the characteristics of anterior uveal tract anatomy?
-iris and ciliary body are extremely vascular
-iris consists of sphincter muscle, dilator muscle, and stroma
-ciliary body has muscle for accomodation
-non-pigmented epithelium of ciliary body produces aqueous humor
-pigmented and non-pigmented epithelium of ciliary body compose part of blood-ocular barrier
What determines pupil size in a normal eye?
balance between tonic activity of parasympathetic nervous system activating sphincter muscle and tonic activity of sympathetic nervous system activating dilator muscle
What happens when light falls on the retina in a normal eye?
-photoreceptors are activated
-reflex pathway involving midbrain structures loops through parasympathetic pathway to constrict pupil
What are persistent pupillary membranes?
strands of tissue that extend from the iris collarette to the lens, cornea, and/or to another area on the iris
Which species/breeds most commonly exhibit persistent pupillary membranes?
*dogs
-basenjis
-corgis
*horses
What is heterochromia iridis?
multi-colored iris; often seen in animals with dilute colors that may also lack fundic pigment and tapetum
What is the treatment for persistent pupillary membranes?
none needed
What is the treatment for heterochromia iridis?
none needed
What is anterior uveitis?
inflammation of the iris or ciliary body leading to breakdown of blood-ocular barrier
Which clinical sign is pathognomonic for anterior uveitis?
aqueous flare
Which clinical signs are highly suggestive or anterior uveitis?
-decreased intraocular pressure
-miosis
What is aqueous flare?
leaking of cells and protein from uveal vessels
How is aqueous flare detected?
-shine a focused light source from the front
-observe from the side; beam of light traversing anterior chamber will be visible if there are appreciable quantities of protein
What is hypopyon?
chronic manifestation of aqueous flare in which precipitate settles out and collects at the bottom of the eye
What are keratic precipitates?
a form of aqueous flare in which precipitate appears to dot the eye
What is miosis?
small/contracted pupil that results due to inflamed tissues releasing prostaglandins, causing the sphincter muscle to constrict
What are the signs of pain due to anterior uveitis?
-blepharospasm
-photophobia
-enophthalmos/sunken eyeball
-prolapse of third eyelid
-depression
What causes pain in anterior uveitis?
ciliary muscle spasm
What can cause redness of the eye in anterior uveitis?
-ciliary flush
-episcleral congestion
What are the two common causes of episceral injection?
-anterior uveitis
-glaucoma
What is the mechanism of corneal edema?
inflammatory cells damage corneal endothelium, decreasing efficacy of ATPase pumps
What causes decreased intraocular pressure in anterior uveitis?
ciliary body inflammation leads to decreased aqueous production and increased non-conventional outflow from dilated leaky vessels
What is synechia?
when the iris adheres to the lens (posterior, more common) or to the cornea (anterior) due to sticky fibrin
What does secondary glaucoma develop from?
iris bombe/cells in angle
What is iris bombe?
-pupil becomes synechiaed posteriorly to the lens for all 360 degrees, preventing aqueous humor flow through the pupil
-aqueous builds up behind iris, causing it to bow forward
-peripheral iris adheres to cornea and obliterates iridocorneal angle
Why do cataracts develop in anterior uveitis?
due to abnormal metabolism in the lens due to abnormal aqueous
Which iridial changes can be seen in anterior uveitis?
-darkening
-congestion
-swelling
-rubeosis iridis/abnormal blood vessels on iris
What are the goals of treatment for anterior uveitis?
-decrease pain by stopping ciliary spasm
-prevent synechia by dilating and/or moving pupil
-decrease cellular and protein exudation to prevent glaucoma (use anti-inflammatories)
Which parasympatholytic drugs can be used in anterior uveitis treatment?
-atropine (can lead to glaucoma)
-tropicamide (used in patients with secondary glaucoma)
What are the characteristics of corticosteroid treatment for anterior uveitis?
-immunosuppressive
-inhibit arachidonic acid metabolism
-anti-fibrotic
-inhibit neovascularization
-must use pred. or dexamethasone; hydrocortisone does not penetrate
-can be used in eyes despite systemic dz, but do NOT use with corneal ulcers
What are the general indications for corticosteroid treatment?
-inflammatory dz
-immune-mediated dz
-reduction of neovascularization/scarring in corneal dz
What are the contraindications for corticosteroid treatment?
-corneal ulceration
-active infection
What are the side effects of corticosteroid treatment?
-slowed corneal epithelialization
-activate latent collagenase/MMPs
-can encourage infection
-can have systemic side effects
What are the topical preparations of NSAIDs?
-ketorolac
-flurbiprofen
-suprofen
-diclofenac
What are the indications for NSAID therapy?
-inflammatory disorders in which steroids are contraindicated
-adjunct to corticosteroid therapy (can use NSAIDs with steroids here!)
What is the contraindication for NSAID therapy?
can inhibit ulcer healing
