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Ophtho (sophomore) > Eye exam (Plummer) > Flashcards

Eye exam (Plummer) Flashcards

1
Q

Anatomy

A
  • Outer vascular tunic
    • cornea
    • sclera
    • limbus (where the cornea and sclera meet)
  • Nasolacrimal duct
  • Lacrimal glands (most dom species)
    • orbital lacrimal gland
    • third eyelid lacrimal gland
  • Conjuctiva: thin vascular mucus membrane covering sclera
  • Middle vascular tunic
    • iris
    • ciliary body: produces aqueous humor
    • coroid: sits between retina and sclera
  • Lens
  • Neurosensory tunic
    • retina
  • Optic nerve
  • Tapetum
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2
Q

Anterior chamber

A

Fluid filled area between cornea and lens I think

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3
Q

Cornea function

A
  • Protection
  • focusing power of eye
    • refracts light
    • like the gross focus on a microscope
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4
Q

Lens function

A
  • Accomodates (changes shape) to focus light onto the back of the eye
  • Like the fine focus on a microscope
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5
Q

Retina function

A
  • Transduction of light stimulus via electrical signals
    • stimulates photoreceptors
      • rods and cones
    • signal modified
      • ganglion cell axons go towards the optic nerve, coalesce, leave through lamina fibrosa and turn into optic nerve behind the eye
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6
Q

Optic nerve function

A
  • Gathers info from retina and carries it to the brain
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7
Q

Basic eye exam

A
  1. Take a proper history
  2. Observe animal in waiting/exam rooms
  3. Observe interactions with owner
  4. Outside to inside
    • adnexa and symmetry
  5. Front to back
    • Cornea
    • Lens
    • Retina
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8
Q

Two main presenting complaints

A
  • Visual deficits
  • Painful eye
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9
Q

Essentials for ophtho hx

A
  1. vision in light and dark?
    • Nigh probs=> may be dz of rod photoreceptors
    • Day probs=> may be dz of cones or axial cataract
  2. vision for stationary and/or moving objects?
    • tennis ball?
    • moving objects=>may be dz of peripheral oculur fundus
    • stationary objects=>may be dz of central retina and ocular opacities w/in visual axis
  3. stairs?
  4. novel environments?
  5. acute or slowly progressing?
  6. trauma, systemic disease, drugs?
  7. clinical signs?
    • other systemic signs? PU/PD?
  8. character if discharge?
  9. what meds have already been given?
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10
Q

Basic instruments

A
  • Focused light beam penlight
  • Schirmer’s tear test strips
  • Fluorescein
  • ophthalmoscope
    • direct/indirect + 20D lens
  • 2-4x magnification
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11
Q

Additional diagnostic equipment

A
  • Culturettes
  • Rose Bengal stain
  • TOpical anesthetic
  • Blades, glass slides
    • take samples of cornea
  • Catheters and syringe
    • flush nasolacrimal duct
  • Tonometer
    • measure IOP
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12
Q

Basic Eye exam

A
  1. pupillary light reflexes
    • helps localize dz
  2. menace response, other estimates of vision
  3. shirmer’s tear test
    • do this before you put stuff in eye (dye, anesthetics)
  4. C & S if indicated
  5. External eye exam with stains
  6. Tonometery
    • before dilation
  7. ophthalmoscopy
    • views back of eye, need to dilate
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13
Q

Path of sensory info received by the eye

A
  • Light focused on back of eye
  • retina stimulated
  • info travels from optic nerve (CN 2, afferent arm) to optic chiasm
  • decussation at optic chiasm
  • then transmitted to pretectal nucleus (CN 2 I think) and edinger westphal nucleus of CN 3
  • signal transmitted back to eye via a motor response CN
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14
Q

Light-induced Pupillary reflexes

A
  • Not synonymous with vision
  • subcortical reflex
  • highly excited and aggressive dogs/cats
    • have dilated pupils that respond poorly
      • due to high levels endogenous circulating catecholamines
  • LA-need an assistant to check consensual response
  • Swinging flashlight test
    • dynamic contraction anisocoria
  • Retinal and prechiasmal optic nerve diseases
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15
Q

Vision/PLR rules of thumb

A
  • visual with normal PLRs
    • A-OK
  • visual with absent PLRs
    • efferent prob CN 3 or iris sphincter
    • mechanical or pharmacological interference
  • Blind with normal PLRs
    • something obscuring vision
      • cataract
    • cortical dz
      • somewhere behind reflex arc
  • Blind with absent PLRs
    • retina
    • optic n.
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16
Q

Dazzle

(Photic Blink Reflex)

A
  • Elicit by a beam of light at ocular fundus, observe a positive blink reflex
    • subcortical reflex: rostral colliculi
    • efferent tract is the facial n.
  • Test for potential vision
    • not a test of vision
  • Use this test if we can’t see the pupil
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17
Q

Menace Response

A
  • First test of actual vision
    • requires intact visual cortex
  • learned response
  • rapid hand movements or cotton balls thrown at patient behind a clear plastic shield
  • patient cooperation is vital
    • tough in puppies and cats
  • Positive test more meaningful than negative test
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18
Q

Palpebral reflex

A
  • medial and lateral canthus
    • CN 5, 7 test
  • no response indicates facial paralysis
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19
Q

Obstacle course

A
  • conduct in exam room
  • change room’s illumination
  • use soft obstacles
  • quiet essential to avoid leading animal with sounds
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20
Q

Summary list of vision tests

A
  • menace
  • drop cotton ball
  • obstacle course
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21
Q

Regional anesthetics

A
  • Lidocaine
  • Carbocaine
  • Bupivicaine
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22
Q

Regional anesthesia

Blocks

A
  • Motor blocks
    • facilitate exam
    • facilitate procedures
    • akinesia: CN 7
  • Sensory blocks
    • facilitate procedures
    • sensory analgesia: CN 5
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23
Q
A
  1. Frontal n. block
  2. Auriculopalpebral n. block
    • CN 7 (Facial)
    • prevents lid closure
    • also used on an eye that is very fragile
  3. Lacrimal n. block
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24
Q

Auriculopalpebral block locations

A
  1. curve of zygomatic arch
  2. top of zygomatic arch
  3. base of ear (triangular shaped divet)

*can also be done in dogs, not really necesary tho

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25
Sensory Blocks
* Supraorbital * aka frontal * medial 2/3 of upper lid * Lacrimal * Line
26
27
External exam
* Prior to sedation (LA) * Discomfort? * Discharge? * Symmetry? * orbit * globe position * eyelids/eyelashes * nictitans
28
Eyelash position
* Eyelash position * pain * ptosis: drooping of upper lid * facial n. paralysis * horner's syndrome * enophthalmos * exophthalmos
29
External exam Globe position/size
* enophthalmos * exophthoalmos * microophthalmos * Phthisis bulbi * shrunken, non-functional eye....? * buphthalmos * enlargement of globe (ie: in glaucoma I think)
30
External exam Orbit/Adnexa
* Position * symmetry * Palpation orbital rim * retropulsion of globe * eye movements * strabismus * eating? mastication? * ventral floor of orbit is soft tissue (carnivores I think) * pain? * abscess/infection more painful than a tumor usually * oral exam * imaging +/- BX * rads, US, CT, MRI
31
Eyelids
* Palpebral and dazzle reflexes * skin scraping * culture and cytology * biopsy * look for defects * abnormal position * lash abnormalities * mass lesions * swelling * inflammation * hyperemia * alopecia
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Entropion
* curving in of an eyelid
33
blephoritis
swelling of eyelid
34
mybomium glands
* in eyelid * contribute liquid material to ocular tear film
35
Tear film quantity
* quantity vs quality * STT measures tear production * quantitative * what's in the lake plus reflex tearing * **prior to putting drugs/stuff in eye** * one minute test * 15-30 mm is normal * not a linear test * def (\< 15mm) can cause * chronic ulcerations * dry/irregular cornea * blood vessels * pigment * other changes to cornea
36
Tear film quality
* TBUT (Tear break up time) * tests mucin fraction * after fluorescein, hold lids open and observe development of dry spots * defeciency if breakup in \< 10s * Rose Bengal * stains areas of mucin and albumin deficiency
37
3 components of tears
* aqueous * lipid * mucin
38
Nasolacrimal Drainage Apparatus | (Jones test)
* Fluorescein passage from eye to nose * couple minutes for dogs * 3-5 minutes for horses * nasolacrimal flush * dacryocystorhinography \* cats may come out on tongue not nose
39
Conjunctiva and nictitans
* Nictitans movements and position * culture and cytology * schirmer's tear test and tear breakup time (TBUT) * Stains: fluorescein and rose bengal * topical sympathomimetics * 1% epinephrine * phenylephrine * BX * Look for * swelling: chemosis * hyperemia * mass lesions * foreign bodies * d/c \***don't forget to look behind the third eyelid!**
40
Cornea
* Clarity * color * bluish haze: edema * creamy white stuff: WBCs * infiltrates * integrity/defects * presence/absence of vessels * thickness/depth \*assessed with slit lamp biomicroscope here
41
corneal culture
* culture prior to instillation of solutions * indications * ulcers with depth * cellular infiltrate * collagenolysis * melting ulcer * severe edema * aerobic/fungal \*horses get lots of fungal infections or bact \*dogs/cats: bacterial \*humans: fungal/bacterial
42
cytology
* Normal cytology * eipthelial cells * Abnormal cytology * WBCs * infectious agents * eosinophils * Stains * Gram * Wright-Giemsa * Diff-Quick * Technique * topical anesthesia * scrape edge of lesion with back of scapula \*quicker than culture results
43
Fluoroscein
* hydrophilic dye * corneal stroma (middle layer) will suck up fluoroscein * outside of cornea is lipophilic, doesn't suck up fluoroscein * Uses * Corneal ulcers * Aqueous leakage (Seidel's test) * green river * NL Passage * Tear film break-up * Angiography & blood aqueous barrier
44
Indications for Fluorescein
* Redness * pain * cloudiness * prior use of steroids * any eye that has been on steroids
45
Corneal sensitivity
* wispy from a q-tip touched to cornea * brachycephalics often have sensitivity deficit
46
Anterior segment AC Iris
* tools to asses * bright, focal light source * slit beam on direct ophthalmoscope * slit lamp * Anterior chamber assessment * clarity, depth, mass lesions * Hyphema, hypopyan, aqueous flare (anterior uveitis) * Iris * color, color changes, position, neovascularization, pupil size, infiltrates, mass lesions, defects
47
Anterior segment Pupil size
* Miosis * indicative of anterior uveitis * drug induced * primary vs secondary * Mydriasis (optic n. or retinal prob) * drug induced vs pathologic * atropine * tropicamide * glaucoma * retinal dz * dyscoria * synechia * iris stuck down to lens * result of inflammation * arms of iris into pupil * uveitis * mass lesions
48
Uveitis
* intraocular inflammation * manifestations * hemorrhage * fibrin * hypopion * aqueous flare
49
Estimating intraocular depth
* Viewing from front and side * use of slit or focal beam of light * iris as a reference point * compare the two eyes * anterior midsirection....
50
Lens
* Two problems * becomes cloudy * moves * Transilluminate * use tapetal reflection * dilate * Size * Clarity vs opacity * nuclear sclerosis * cataract * Position * anterior luxation * posterior luxation * subluxation
51
Galucoma
* Index of suspicion * Clinical signs * pupil size * tonometry * gonioscopy
52
Tonometry
* Estimates IOP * two main methods * tonopen * tonovet: rebound stenometer * normal range * 10-15 mmHg * Brachiocephalics * tend to have higher IOP * older animals * tend to have lower IOP * Method * head position important * below heart can cause venous stasis * hold a sedated horses head up * do before dilation * increases IOP
53
Tonometry tools
* Digital * Applanation * Schiotz: OLD SCHOOL * Tonopen * Rebound * TonoVet
54
Iridocorneal Angle
* Open meshwork through which AqH flows * space where iris and cornea come together * Can change * narrow * become fibrotic * scarring * inflammation * IOP elevations
55
Posterior segment
* easier to do if dilated * evaluates * structure posterior to lens * vitreous * retina * optic nerve * clarity * inflammation * degeneration * tools * direct ophthalmoscope * indirect ophthalmoscope * panoptic
56
Pharmacologic dilation
* 1% Tropicamide * onset of action 10-20 minutes * duration 4-6 hours * 1% atropine * onset of action - depends on dz * duration * several days in normal dog (depends on pigmentation) * \> 14 days in normal horse eye * 2.5% phenylephrine
57
Vitreous
* not evident unless pathology present * congenital abnormalities * persistent hyaloid artery / remnant * acquired opacities * transudates / exudates * hemorrhage * asteroid hyalosis - age related * degeneration
58
Components of vitreous
* Primary * Hyaloid artery * blood vessel that feeds developing nerve before eye is completely developed * Secondary * Gel that is the adult vitreous * Tertiary * zonules
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Ophthalmoscopy
* Direct * image real, upright, and 10x-15x * small pupil * close to patient * red free filter * diff pigment from hemorrhage * cobalt blue filter * excites fluorescein * different apperture sizes * may be able to put slit on it * diopter lens settings allow visualization of different parts of the eye in focus * Indirect (pen light and lens) * image virtual, inverted, and 2x-4x * wider field of view * stereopsis * distance from patient
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Magnification and orientation
* Direct * 10-15x * upright and real * small field * Panoptic * 3-7x * upright and real * intermediate field * Indirect * 2-4x * upside-down, backwards and virtual * large field: survey view
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Ophthalmoscopy What do look for
* optic disk * size * shape color * elevation * depression * Retinal vessels * presence/absence * number * tortuosity * thinness * attenuation * color * inflammatory lesions * active * scars * Hemorrhages * Detachments * Tears
63
Tapedum and nontapedum
* reside in superior choroid * color * tapetum * blue or blue green usually * varies with coat color: can be yellow/rust/absent * nontapedum * black to brown usually * varies with coat color * varisou degrees of chorioretinal hypopplasia * look for * peripapillary scarring * irregularities * hyper/hyporeflectivity

Ophtho (sophomore) (11 decks)

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