the ocular surface Flashcards
1
Q
what makes up the ocular surface
A
- conjunctiva
- corna
2
Q
conjunctiva
A
- most exposed of all the mucous membranes
- relatively transparent
- blood vessels, globlet cells, lymphoid tissue, collagen and elastin
- variable amount of melanosis normal in dog
3
Q
conjunctiva innervation
A
ciliary nerves
4
Q
what does the conjunctiva line
A
eyelids, third eyelid, and reflects onto the globe
5
Q
different parts/areas of conjunctiva
A
- palpebral conjunctiva
- nicitating membrane
- bulbar conjunctiva
- conjunctival fornix
6
Q
layers of conjunctiva from superficial to deep
A
- bulbar conjunctiva
- episclera (loose fibrous elastic tissue)
- tenon’s capsule (thin fascial sheath)
- sclera
7
Q
function of conjunctiva
A
increases mobility of eyelids and globe
- freely moveable except at limbus
- redundancy at fornix
barrier against microorganisms and prevent desiccation of cornea
- muscin produced by globlet cells
- traps debris
8
Q
what is the cornea
A
- transparent front of outer fibrous tunic
- avascular - pre-corneal tear films
9
Q
what is the limbus
A
- cornea meets the sclera
- transition zone between cornea and conjunctival epithelium
10
Q
cornea innervation
A
ciliary nerves
11
Q
histology
A
epithelium
- firmly adhered to underlying stroma
- 6-15 layers
stroma
- regularly arranged collagen
- avascular
single endothelial cell layer
- descemet’s membrane
12
Q
transparency
cornea
A
- essential for vision
- results from (avascular, regularly arranged collagen, relatively dehydrated - endothelial Na, K-ATPase pump, epithelial barrier)
13
Q
function of cornea
A
refraction of light
- smooth outer surface
- continuously replaces epithelium
- pre-corneal tear film
main barrier to penetration by micro-organisms
14
Q
slit lamp biomicroscope
A
use to look at changes in corneal transperancy and integrity
15
Q
SD-OCT (spectral domain optical coherence tomography)
A
- accurate evaluation of each component of cornea
- real-time evaluation with absence of corneal contact
16
Q
conjunctival disease
A
- very common
- conjunctival vessels sensitive to irritation, easily congested
- conjunctivitis (most common)
17
Q
corneal disease
A
- trauma - corneal ulcer
- tear film abnormalities - dry eye (KCS)
- corneal edema
- keratitis
- results in loss of transperancy, integrity, distrubed vision
18
Q
loss of transparency
A
- corneal pathology results in loss of transparency
- disturbed vision
19
Q
conjunctiva and cornea diagnostic tests
A
- schirmer tear test
- fluorescein dye
- rose bengal stain
- cytology, culture
- biopsy
- PCR
- corneal sensitivity and thickness
20
Q
fluoresceine dye
A
- corneal integrity
- dye is hydrophilic (readily binds to exposed stroma, repelled by epithelium)
- corneal ulcer stains green
21
Q
rose bengal stain
A
- devitalized epithelial cells (stain pink)
- FHV-1 dendritic ulcers
22
Q
cytology
A
- frequently useful
normal
- sheets of epithelial cells
- large, round homogenous nuclei
- abundant cytoplasm
abnormal
- examine for cellular alterations, bacterial and inclusion bodies
23
Q
0.5% proparacaine
A
- local anesthetic (dogs - 15-25 min, cats - 5 min)
- refrigerate
- epithelial toxic
24
Q
culture
A
- bacteria cultured from conjunctival sac normal animals
- reserve for persistent, recurrent or non-responsive conjunctivitis
25
corneal sensitivity
* evaluates ophthalmic branch of CNV
* esthesiometer (semi-quantified device, sensitivity in different areas)
26
corneal thickness
* pachymetry
* simple, quick way to measure corneal thickness
27
pre-corneal tear film (PCTF)
* nourish, lubricate, cleanse ocular surface
* optical activity
* antibacterial
* alterations in tears dynamics (compromise function, inflammation, metaplasia, necrosis of ocular surface cells)
28
PCTF secretion
* tri-laminar fluid comprises (lipid, aqueous, mucin)
* complex interactions between layers
* transparent, tri-laminar tear film
29
function of aqueous layer
serves metabolic needs of avascular cornea (lubricates and cleanses
30
what is the aqueous layer produced by
* orbital lacrimal gland (majority)
* gland or third eyelid/accessory
31
aqueous layer innervation
by both sympathetic and parasympathetic
32
lipid layer
* meibomian glands (cholesterol waxy lipids
* retards evaporation
* contributes to tear film stability
33
mucin layer
* conjunctival globlet cells (mucin, conjunctival fornix)
* promotes smooth ocular surface
* traps bacteria, foreign material
* contributes to tear film stability
34
tear drainage
* lacimal puncta (tear ducts)
* slit-like openings at mucocutaneous junction upper and lower lids
* only inferior punctum rabbits
* enter puncrta by combination of gravity, capillary pull, and pump mechanism
35
nasolacrimal duct system
* tears flow through **canalicular system**, which coverges at lacrimal sac (lacrimal bone)
* continues as **nasolacromal duct** to nasal opening (puncta)
* **nasal puncta** (located in nasal vestibule at margin or alar fold)
36
PCTF disorders
* desiccation, inflammation of conjunctiva and cornea
* KCS (aqueous deficiency, dry-eye is most common ocular disease in dogs)
* melbomianitis/bleparitis (loss of tear film stability)
37
tear drainage abnormalities
* tear overflow (epiphoria)
* obstruction of nasolacrimal duct system (foreign body)
38
PCTF diagnostic tests
* schirmer tear test
* tear film breakup time
39
schirmer tear test
* measures volume of aqueous tears
* dog 15-20 mm/min
* values vary with age, breed
* cat - often lower than expected
* compare both eyes
* diagnostic test of choice for KCS
40
tear film break up (TBUT)
* lipid and mucin abnormalities - tear film stability
* time taken for first "dry spot" to appear on cornea after complete blink
* cats - 12-21 sec, dog - 20sec
41
abnormalities of drainage
* nasolacrimal patency (jones test, nasolacrimal duct flush)
* dacryocystohinography
42
jones test
* apply fluorescein and wait 4-10 min for it to appear in nares
* positive test = nasolacrimal duct system patent
* negative test = suspicious for obstruction
43
flush nasolacrimal duct
* syringe attached to lacrimal cannula or blunted needle
* cannulate superior punctum
* negative test confirms obstruction
