Final Exam - Ophthalmic Exam Flashcards
what ocular lesion is seen in this photo?
rubeosis iridis - engorged iris radial arterioles & new blood vessels with uveitis
this dog has hypertriglyceridemia - what is seen on its ocular lesion?
pale, fat-laden vessels
this dog has vasculitis - what is seen on its ocular exam?
retinal vessel damage causing hemorrhage
what ocular lesion is shown? what part of the eyes are you evaluating?
optic neuritis - looking at the CNS
T/F: ocular manifestations of systemic disease are common in veterinary medicine
TRUE
what lesion is shown in this photo as a result of stomatitis?
pseudobuphthalmos
what ocular lesion is shown in this dog that is occurring secondary to diabetes mellitus?
equatorial vacuoles in the lens
what may be seen on ocular exam that supports anemia in a cat?
thin, pale vessels
what does OMSD mean?
ocular manifestations of systemic disease
why do owners often readily recognize ocular disease in their pets?
eye contact is a significant factor in the human-animal bond, so they are quick to notice changes
what is the most important component of a successful ophthalmic exam when you’re trying to exam/image the globe & its associated structures?
room lights off!!!!!!!
what is the most important tool needed for an ophthalmic exam?
controlled light source in a dark environment
what components make up the tools required for a successful ophthalmic exam?
controlled light source in a dark environment, means of dilating the pupil/performing fundoscopy, means of achieving magnification, means of discerning depth, & minimum database resources for STT, fluorescein stain, & tonometry
why is an incandescent pen light not a great light source for an ophthalmic exam?
it is too dim
why is an LED flashlight from an iPhone not a great light source for an ophthalmic exam?
it is too bright by itself
what are your appropriate light source choices for an ophthalmic exam?
halogen lights - finoff transilluminator & otoscope
what challenges are presented when trying to perform an ophthalmic exam in a well lit environment?
creation of specular reflections that obscure/prevent/confuse your intraocular exam
what should you do with the lights when you’re examining/imaging the head/orbit/eyelids?
room lights on!!!!
what is the benefit of using a dark environment for an ophthalmic exam?
removing environmental light allows the examiner to use imposed light to highlight specific aspects of the eye when subtley changing light to highlight iris topography & lens opacities
_____ ______, or mydriasis, facilitates fundoscopy
pupil dilation
what is the time of onset for tropicamide? How long does it last?
15-20 minutes for onset & it lasts 2-4 hours
what is the purpose of using tropicamide?
dilating the pupil
what is the orientation provided when using the indirect fundoscopy technique?
it is upside down & backwards
what is the preferred technique used for performing fundoscopy?
indirect using a light source & macro lens
how is direct fundoscopy done using an iPhone?
white tape is placed over LED flash & flash is toggled on to run continuously in video mode, move the phone within 1cm of the patient’s eye & record with the room lights turned off!!!
what is one limitation of using a smart phone for direct fundoscopy regarding the corneal or lens opacity?
cornea or lens opacity - smart phone software will focus on the nearest object to the lens
what is shadowing dependent on when doing fundoscopy with a smart phone?
associated with the distance between the flash & wide-angle camera lens (most often the corner lens)
why is direct fundoscopy done with a smart phone not great for looking at the fundus?
direct technique will not allow visualization of the peripheral fundus
T/F: centered camera lenses can still be used effectively for direct fundoscopy with a smart phone
FALSE
why is a smart phone with a centered camera lens not an option for direct fundoscopy?
the patient’s nose & camera lens’ center location prevent the camera lens from being positioned closely over the eye
how is indirect fundoscopy performed when using a smart phone?
white tape is placed over the LED flash (very important for safety/patient comfort), flash is toggled on for continuous function, &align the phone between your eye & the condensing lens attempting to fill the condensing lens & camera lens with the fundus
what limitations are posed by indirect fundoscopy with a smart phone?
initially challenging, but no other limitations unlike the direct technique
why is the indirect technique for fundoscopy more valuable for veterinary patients?
a large field of view, provided by the indirect technique, allows for a more rapid & thorough fundus examination
what fundoscopy technique provides better magnification & is initially easier to perform?
direct technique of fundoscopy
why should you initially look at the head/eyes at rest with the room lights on when working up a patient?
you can assess the degree of discomfort at rest
what is the minimum level of magnification you need to see in practice for an ophthalmic exam?
need to see 3-5X magnification
do you want the room lights on or off when looking at the magnified eye?
room lights off!!!!!!!
how much magnification is provided with an otoscope? What about an optivisor?
otoscope - 3x
optivisor - 3-5X
what are your two options for achieving magnification in general practice using a smart phone?
video imaging using maximal optical zoom or video imaging using a macrolens (preferred)
how is video imaging using maximal optical zoom done on a smart phone? what limitations may be met?
for iPhone 7 & newer - 2X zoom doesn’t lead to any loss of resolution or detail, but above 2X, digital zoom is employed which leads to image pixilation
T/F: when using a macro lens, the tape placed over the flash is completely independent of the lens
TRUE
what should you have the room lights at when imaging the globe? why?
always off!!! if you leave it on, specular reflections will dominate/obscure & you won’t be able to see depth of structures, but if they are off, the ocular surface & intraocular environment can be seen
what is the most common macro lens mistake?
overlap of the LED light & band and/or tape
what are the two techniques used for discerning ocular depth?
optical dissection & specular reflection
optical dissection allows the examiner to do what?
allows the examiner to distinguish anatomy & pathology in the anterior segment of the eye
what structures are included in the anterior segment of the eye that are easiest to distinguish upon examination?
cornea, anterior chamber, & lens
optical dissection requires what?
requires a focused, narrow, bright beam of light in a dark environment
is the slit beam setting used for optical dissection of the anterior chamber?
nope
what otoscope settings are approprate for optical dissection?
smallest aperture or the split beam view
what is the purpose of optical dissection?
allows us to detect depth & clarity of ocular media
how does optical dissection undercover pathology?
uncovers pathology by means of the tyndall effect (light passing through that shows particles suspended in solution - think movie projector light & how you can see dust in front of it)
when doing optical dissection to assess for aqueous flare, what do the room lights need to be set at?
need to be off
how is interpretation of the specular reflection used to discern depth on opthalmic examination?
can be used to determine which one of the white opacities is associated with the ocular surface
what is the concept of using specular reflections to discern depth of ocular structures?
involves interpretation of natural & imposed reflections to determine the smoothness of a reflective surface
what structures must be healthy to provide a predictable specular reflection of an eye?
healthy tear film, corneal epithelium, and/or anterior corneal stroma
what is an example of how specular reflections can reflect focal pathology?
normal specular reflection seen in a normal region of the cornea with fluorescein dye vs abnormal specular reflection in an abnormal region of the cornea indicating the presence of an ulcer
what is an example of using specular reflection to discern a surface disease from an intraocular disease?
normal specular reflection seen in an intraocular disease (uveitis) vs abnormal specular reflection in a surface disease (anterior corneal stromal lipid infiltration)
in health, what does the ocular surface consist of?
precorneal tear film, corneal epithelium, & anterior corneal stroma
what are the limitations when using specular reflection as a tool for discerning depth?
surface reflections from natural light, eyelids/periocular hair/photographer’s hand/clothing, can obscure or confuse the examiner’s assessment of the eye
T/F: with natural light, intraocular structures are obscured on specular reflection, but we can say that the ocular surface is healthy (if a predictable reflection is seen)
TRUE
what is the most common artifact seen in specular reflection?
examiner’s hand/clothing
what does the schirmer tear test assess?
baseline & reflexive production of the aqueous portion of the precorneal tear film
what does the schirmer tear test help diagnose?
keratoconjunctivitis sicca
what are the guidelines for performing a schirmer tear test?
performed before any other drops/ointments, performed before sedation/anesthesia, performed for 60 seconds
what are examples of fragile eyes that you wouldn’t do a schirmer tear test on?
deep/stromal corneal ulcers, corneal perforations/ruptures, & descemetoceles
what are the normal results on schirmer tear tests for dogs & cats?
dogs - >15mm wetting/min (basal & reflex tearing) cats - unpredictable!
why do we use fluorescein dye?
it is a hydrophilic dye that binds to other hydrophillic substances (tear film & corneal stroma) that will fluoresce bright green under cobalt blue light
what are the 3 main clinical uses of fluorescein stain?
diagnosis & characterization of corneal ulcers, jones test of nasolacrimal patency, & seidel test of corneal perforation
what components of the eye are hydrophilic & will take up fluorescein dye?
tear film is hydrophilic - will take up dye & stroma is hydrophilic & will stain bright green
what needs to be done if you get a positive fluorescein stain of the tear film?
you need to flush it!!!!!!
what is a common cause of a false positive to fluorescein dye?
schirmer smudge - creates a false positive (not actually on the eye)
does a negative jones test verify blockage of the nasolacrimal duct?
nope
what does a positive jones test indicate?
verifies that the nasolacrimal duct is patent
what does a positive seidel test indicate?
verifies perforation of the cornea by showing aqueous humor leaking through a fluorescein stained tear film
what is the most common cause of blindness in animals?
glaucoma
what is tonometry? What two methods are used in practice?
measurement of intraocular pressure in mmHg - applanation (tonopen) & rebound (tonovet)
what are the guidelines for performing tonometry?
not performed in fragile eyes & done before pupil dilation (tropicamide) due to possible pressure elevation!!
with repeat tonometry tests, what reading is your most accurate?
lowest value
what is the normal result of tonometry?
normal is 10-20 mmHg, under 25 mmHg at all times
intraocular pressures > 25 mmHg with vision loss is defined as what?
glaucoma
low intraocular pressures are consistent with what condition?
uveitis
what is the main difference in performing tonometry between a tonopen & tonovet?
tonopen requires topical anesthetic (proparacaine) & tonovet does not
what is the most common ophthalmic emergency seen in veterinary patients?
deep/stromal/infected corneal ulcers
what must you own in your practice to diagnose glaucoma?
must have a tonometer to measure intraocular pressures
T/F: if left untreated, glaucoma can cause blindness within a few hours
TRUE
what are some reflexes that are testing during the cranial nerve/vision assessment aspect of the ophthalmic exam?
palpebral reflex, menace response, pupillary light reflex, dazzle reflex, oculocephalic reflex, corneal reflex, & cotton ball test
what cranial nerves are assessed with the palpebral reflex?
afferent - CN V
efferent - CN VII
what cranial nerves are assessed with the menace response?
afferent - CN II
efferent - CN VII
what cranial nerves are assessed in the pupillary light reflex?
afferent - CN II
efferent - CN III
what cranial nerves are assessed in the dazzle reflex?
afferent - CN II
efferent - CN VII
what cranial nerves are assessed in the oculocephalic reflex?
intact CN II, peripheral/central vestibular components, CN III, IV, & V
what cranial nerves are assessed in the corneal reflex?
afferent - CN V
efferent - CN VI & VII
does CN II need to function for a positive oculocephalic reflex?
doesn’t have to be functional to get a positive reflex, but it needs to be present initially for the reflex to develop
what is neurotrophic keratitis?
loss of the ophthalmic branch of CN V
what reflexes/responses specifically identify the function of cranial nerves & also help assess for the presence of vision?
menace response, pupillary light reflex, & dazzle reflex
what tests are done for orbital symmetry in an ophthalmic exam?
orbital palpation, dorsal view assessment, & retropulsion of the eyes
what are the two purposes of retroillumination?
used to initiate & align fundoscopy as well as to confirm the presence of any opacity (looking at tapetum lucidum) located between the cornea & fundus
T/F: when doing a PLR, both direct & consensual should be recorded
TRUE
