Lacrimal System and Conjunctiva part 2 Flashcards
what is a way to quantitatively test the tears produced
a Schirmer’s test
what is the tear meniscus height at the lower lid margin
0.75mm
what is a noninvasive way to test the tear film stability
with a keratometer (watching the mires to see if they stay stable and clear) about 10 sec
what is an invasive way to measure the tear film stability
TBUT (tear break up time) with flourescein (10 sec)
how can you test the ocular surface integrity
tissue sampling (impression cytology-counting goblet cells in conjunctiva) or staining techniques
when would you give a Schirmer’s test
dry eye or excessive tearing
what are the steps of the Schirmer’s test
instill anesthesia and wait a min, wipe excessive tears, place strip on temporal side, wait 5 min, record results
why does the eye need to be numb for a Schirmer’s test
otherwise you are testing the reflex tearing, no the basic secretion
why do you place the strip on the temporal side during a Schirmer’s test
because the tears drain medially and it will give a false measurement
what is a normal outcome for the Schirmer’s test
greater than or equal to 15mm
what is a variation of a normal result of a Schirmer’s test
an older individual (over 60) may only have 10mm but not complain of dryness or epiphora
what can affect the outcome of a Schirmer’s test
placement of the strip in the eye, age, effect of anesthesia, reflex tearing, and subjective measurement
what is a mild dry eye test result for Schirmer’s
9-14 mm
what is a moderate dry eye result for Schirmer’s
4-8 mm
what is a severe dry eye result for Schirmer’s
less than 4 mm
what is the first stage of secretion of lacrimal gland electrolytes and water
the acini cells secrete a fluid that has an electrolyte composition similar to that of plasma
what is the second stage of secretion of lacrimal gland electrolytes and water
as the fluid passes through the duct system, the ductal cells modify the fluid by secreting a fluid rich in potassium chloride (KCl)
what drives acinar cell electrolyte secretion
a sodium potassium ATPase pumping sodium out of the cell and potassium into the cell
what is the solution called at low fluid rates
hypertonic
what is the solution called as the flow rate increases
isotonic
how do the ductal cells modify the fluid as it passes through the duct system
by secreting a fluid rich in potassium chloride
what ions does the lacrimal gland contain
Na+, K+, Cl-, HCO3, Ca2+ and trace amounts of other ions in the same concentration as plasma (except K+ and Cl- which are higher concentrations)
what stimulates the cells to secrete
nerves, peptide and steroid hormones present in the blood
what type of nerves innervate the lacrimal gland
parasympathetic nerves, sympathetic nerves, and sensory nerves
what specifically do the nerves and peptide hormones stimulate secretion of
electrolytes, water and the regulated proteins
what specifically do the steroid hormones stimulate
the secretion of the constitutive proteins
does stimulation of the sympathetic nervous system result in change in tear secretion
no
what parasympathetic nerves are responsible for the secretion of tears
CN 7 facial nerve
what are 5 stimulants that can cause secretion of the lacrimal gland
sensory nerves at optic surface, a bright light hitting the optic nerve, acetylcholine and vasoactive intestinal peptide (VIP) and norepinephrine
what is the conjunctiva
a mucous producing tissue lining the ocular surface (sero-mucous secreting tissue)
what part of the external eye is the most immunologically active tissue
the conjunctiva
how many neutrophils are in a normal conjunctiva
6,000
how many lymphocytes are in a normal conjunctiva
14,000
what can provoke conjunctival reactions
infections, allergy, and inflammation
what are 2 structural changes in allergic reactions of the conjunctiva
papillae formation and follicle formation
what are papillae
areas of conjunctival hypertrophy, contain eosinophils and neutrophils
how can you distinguish papillae from follicles
papillae have blood vessels in the centers
which lid, upper or lower, are papillae normally found in
the upper lid (must evert the lid to see them)
what are follicles
clear, fluid-filled pockets, containing lymphocytes and macrophages
what are 2 granulocytes that are not commonly found in normal conjunctiva epithelium
eosinophils and basophils
what 2 diseases of the conjunctival epithelium have eosinophils and basophils present
vernal conjunctivitis and giant papillary conjunctivitis
where does a CL usually end up in the eyelid when it becomes displaced
in the superior fornix since it has the greatest depth
what are the two layers of the conjunctiva
epithelium and stroma
how many stratified layers are there in the epithelium
2-4 stratified epithelial cells
when the conjunctival epithelium becomes the corneal epithelium, how many stratified layers does it have
5-7, difference begins at the limbus
what are located in the palisades of vogt
limbal stem cells and increased wing cells
what are goblet cells
unicellular mucin-secreting glands (holocrine) within conjunctival epithelium
which area of the conjunctiva has the most goblet cells
fornix and palpebral conjunctiva
what does the conjunctival stroma consist of
adenoid layer, deep fibrous layer, and a rich network of capillaries
why does the conjunctiva need a rich supply of nutrition
for regeneration of epithelium and formation of new goblet cells
where are the glands of Wolfring located
in deep fibrous layer (tarsal plate)
where are mast cells found
in adenoid layer of conjunctival stroma
does the conjunctival epithelium normally have mast cells
no they are an inflammatory cell and usually found in the adenoid layer of the stroma
when mast cells are present in the conjunctival stroma, how many are there
6,000 per cubic millimeter
what is the diameter of a mast cell
20 micrometers in diameter
what are mast cells responsible for
immediate hypersensitivity allergic reaction
what do mast cells contain
several perforated chemical mediators of inflammation, histamine, and heparin
what fills the cytoplasm of mast cells
30-100 metachromatic granules
what happens when mast cells are bound by IgE (allergies)
dramatic changes occur in cell membrane and cytoplasm, physical properties change (membrane becomes more permeable to Ca++ ions) and leads to edema
which blood vessels are engorged in conjunctival infections
superficial posterior vessels
which blood vessels are engorged in keratitis or iritis
deep ciliary vessels
does the conjunctiva have lymphatics
yes
which way does the temporal lymph drain in the conjunctiva
towards lateral extremes of lid, eventually connecting with parotid node
where does the medial conjunctival lymph drain
to the submandibular lymph glands
