Lecture 8 2/17/25 Flashcards
What are the two normal components of tear production?
-basal secretion
-reflex secretion
Which tests are use to measure aqueous tear production?
-schirmer tear test
-phenol red thread test
-endodontic paper point test
What is the definition of quantitative dry eye/KCS?
deficiency in the production of the aqueous portion of the tear film
What is the definition of qualitative dry eye?
-deficiency in the production of mucin or lipid
-leads to poor tear quality, tears that do not adhere well, and rapid evaporation of tears
What are the clinical signs of quantitative dry eye/KCS?
-hyperemic conjunctiva
-mucopurulent discharge
-keratitis
-dry appearing cornea
Which diagnostics are used to diagnose quantitative dry eye/KCS?
-clinical signs
-schirmer tear test
Which diagnostics are used to diagnose qualitative dry eye?
-clinical signs: KCS signs +/- epiphora
-tear film break up time
-lissamine green dye staining
-rose bengal dye staining
What are the differential etiologies of KCS?
-immune-mediated (most common)
-drug induced
-endocrinopathies
-inflammatory
-neurogenic
-infectious
-lacrimal gland agenesis/hypoplasia
-iatrogenic
-radiation therapy if eye is in field
Which drugs can cause KCS?
-atropine (temporary)
-general anesthesia/sedation/opioids (temporary)
-sulfa drugs/TMS (toxic)
Which drug classes cause decreased tear production and therefore warrant monitoring of the patient with schirmer tear tests?
-sympathomimetics
-parasympatholytics
Which endocrinopathies have potential to cause KCS?
-diabetes mellitus
-hypothyroidism
-possibly cushing’s
Which inflammatory conditions can result in KCS?
-chronic conjunctivitis
-third eyelid gland prolapse
What are the surgical techniques for correcting a third eyelid gland prolapse?
-pocket techniques
–modified morgan pocket
-tacking techniques
–orbital tacking
-ventral rectus muscle tacking
Which other lesions can occur with neurogenic KCS due to the proximity of the nerves?
-dry nose
-trigeminal neuropathy/neurotrophic keratitis
-horner’s syndrome
-facial nerve paralysis
Why is it important to do a schirmer tear test on any patient presenting with a facial neuropathy?
dry eye may not be the presenting complaint but could be occurring concurrently; important to diagnose and treat it
Which drugs can be used to treat neurogenic KCS and why?
-parasympathomimetics such as pilocarpine
-increases tear production due to denervation hypersensitivity/increased number of receptors
Which infectious diseases can cause KCS?
-canine distemper virus
-feline herpes virus
What can cause iatrogenic KCS?
removal of the third eyelid gland
What are the treatment steps for KCS?
-replace tears w/ artificial gels/ointment
-create more tears using cyclosporine A/tacrolimus
-treat infections with topical antibiotics
-topical steroids may be useful; use caution
-pilocarpine for neurogenic KCS
What are the characteristics of lacrostimulants such as cyclosporine A and tacrolimus?
-take around 4 weeks to begin working
-new studies show around 50% of cases can eventually discontinue the medication
What are the characteristics of surgical parotid duct transposition?
-last resort procedure to restore corneal moisture
-goals are to improve comfort and retain vision
-best in patients with blepharospasm that are developing corneal opacity
-open and closed methods
-complications include fibrosis of duct, corneal mineralization, overproduction, underproduction, poor salivary secretions, and sialolith formation
What are the characteristics of cyclosporine implants?
-implant is placed under cornea for slow-release of drug
-can improve clinical signs even if schirmer tear test does not improve
-expensive implant that must be replaced every year under GA
What are the characteristics of emergency corneal stabilization?
-conjunctival grafting done in the case of very deep ulcers, descemetoceles, and perforations
-must be done to save the cornea since tear production requires weeks to increase with treatment
What are the two sets of blood vessels on the surface of the globe?
-conjunctival
-episcleral
How is conjunctival hyperemia diagnosed?
-visualization of small, branching blood vessels
-blanching occurs with topical epinephrine/phenylephrine
-can be moved with a q-tip
What are the causes of conjunctival hyperemia?
-conjunctivitis
-KCS
-eyelid abnormalities
-ulcers
How is episcleral injection diagnosed?
-big corded vessels radiating away from the limbus
-do not blanch right away with phenylephrine
-do not wiggle when a cotton swab is used to move the conjunctiva
What are the causes of episceral injection?
-anterior uveitis
-glaucoma
-infected ulcer
What must be ruled out whenever a patient presents with a “red eye”?
-corneal ulceration
-KCS
-anterior uveitis
-glaucoma
What can a red eye be the first sign of?
blinding disease
