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Ocular Biology > Conjunctiva > Flashcards

Conjunctiva Flashcards

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1
Q

Conjunctiva

A

thin, vascularized mucous membrane that lines eyelids

major mucous producer = goblet cells in epithelial layer

reflected at fornices onto anterior surface of eyeball

conjunctival sac - forms potential space

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2
Q

Parts of conjunctiva

A

fornix with redundant conjunctiva

bulbar

palpebral

conjunctival sac

cul de sac

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3
Q

Conj vs. potential combating infection

A

highly vascular

cell types for initating and participating in defensive inflammatory rxn

surface has microvilli and enzymes to engulf and neutralize foreign particles

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4
Q

conjunctiva epithelium

A

stratified squamous non-kertinizing epithelium

more stratified columnar/cuboidal in tarsal, fornix and bulbar epithelium

2-15 cell layers thick: basal, intermediate, and superficial cell layers
-rests on substantia propria (stroma)

  • rests on basement membrane, attached by hemi-desmosomes
  • epithelial cells connected to one another by desmosomes (attached to intermediate filaments of keratin)
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5
Q

cell types in epithelium

A

microvilli coatced with mucopolysaccarhides

goblet cells (mucous secreting)

melanocytes- protective, absorb UV

langerhan cells

intraepithelial lymphocytes

many polymorphonuclear leukocytes found in inflammatory conditions

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6
Q

langerhan cells

A

similar in morphology to macrophages

functino: take up and process microbial antigents

present in suprabasal portion of conjunctival epithelium at limbus

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7
Q

melanocytes

A

scattered in basal layer of limbal and bulbar epithelial

may play protective role for stem cells against UV exposure

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8
Q

goblet cells

A

large cells 25 u x 25 u

mucin granules within cytoplasm of goblet cells => released by apocrine secretion

production of mucus

stabilizes tear film

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9
Q

palpebral (tarsal) conjunctival epithelium

A

5-6 layers thick

palpebral conj epithelium more cuboidal

numerous and prominent microvilli on free surface of palpebral conj

cells with long microvilli line deep crypts that extend into epithelium

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10
Q

substantia propia (stroma)

A

connective tissue layer beneath epithelium with great anti-infectious capability

cell types: mast cells (histamine), lymphocytes, plasma cells and neutrophils

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11
Q

layers of conjunctiva

A

epithelium, substantia propria => adenoid layer (lymphoid layer = lymph) and fibrous layer (blood supply and innervation)

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12
Q

Substantia propria layers

A

2 layers:

superficial lymphoid layer (not present at birth => develops few months post-natally)
-most developed in fornices

deeper fibrous layer: collagenous and elastic tissue, blood vessels, nerves, glands of Krause, and larger lymph vessels

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13
Q

pinguecula

A

localized, elevated, yellowish-white excresence noted medially and laterally close to limbal margin (localized at palpebral opening usually 3 or 9 position)

represent age-related elastotic degeneration including collagen breakdown of the stroma

initial event: limbal stem cell damage by uv exposure causing fibroblasts producing elasting fibers twisted and degradation of collagen fibers (usually medial and later more exposed to UV)

underlying sclera acts w/ high reflectivity to furth back expose the tissue to UV (Sclera reflects uv to conj => more damage)

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14
Q

pterygium

A

basophilic degeneration of bulbar conjunctival stroma

histopathology: same as piguecular but with corneal involvment; elastotic degeneration of collagen and fibrovascular proliferation (limbal stem cells affected in pterygium => more visual consequences)

usually damage to limbal stem cells by prolonged UV exposure initial event to cause pterygium

other factors affecting: UV, wind, sand

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15
Q

3 regions of conjunctiva

A

palpebral conjunctiva (eyelids)

conjunctival fornices (redoubled fold of conjunctiva)

bulbar conjunctiva (eyeball)

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16
Q

palpebral conjunctiva

A

lines inner surfaces of eyelids; tightly bound to tarsal plate
-subepithelial substantia propria = thin

lacrimal puncta opens on palpebral conjunctiva

lining of palpebral conj continous with lining of inferior meatus of nasal cavity

punctal opening and lining is continous with lining of canaliculi, lacrimal sac, and nasolacrimal duct

dacryocystitis: infection in lacrimal sac

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17
Q

zones of palpebral conjunctiva (3)

A

marginal zone: margin of lid; transition between skin of eyelid and conj. epithelium
-puncta opens on this zone

tarsal zone: thin, transparent, tarsal glands beneath; very vascular (meibonian glands within tarsal zone)

orbital zone: between upper border of tarsus and fornix

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18
Q

subtarsal sulcus (in palpebral conjunctiva)

A

2mm from lid margin; important in trapping and removing foreign particles and debris

in marginal zone

palpebral conj represents area for pathologic changes related to infectious and inflammatory processes or allergic

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19
Q

Follicles

A

accumulation of lymphocytes; miniature lymph nodes composed of lymphocytes, macrophages, and plasma cells
(think substantia propria when follicles seen)

normal in childhood

consistent with dx of viral infection or allergic tissue response (think viral/allergic)

20
Q

conjunctival follicle

A

tissue reaction to irritation

no significant difference among follicles caused by identifiable irritant, unknown agent, and noted in acute infections follicular conjunctivitis

follicle size related to severity and duration of inflammatory stimulus

21
Q

where are follicles found and how do they look

A

usually inferior palpebral conj and inferior fornix

round, discrete, clear mound encircled by vascular ring: 0.5 to 5 mm dia.

could be limbal follicles

22
Q

papillae/ papillary hypertrophy

A

a nonspecific reaction occurring in chronic and acute forms of conjunctivitis; more typically on upper tarsal (palpebral) conjunctiva

consists of focal aggregates of acute inflammatory cells (PMN example)

has presence of blood vessels at center (follicles do not)

23
Q

size of papillae

A

can be relatively small and give velvety appearing (in bacterial conjunctivitis)

or

giant papillae: found in allergic diseases or long standing contact lens wear

24
Q

conjunctival papillae

A

reddish, flat topped raised areas

red velvety appearance to palpebral conj

central core of numerous dilated blood vessels with surrounding lymphocytes and covered by hypertrophic epithelium

consistent with bact. conjunctivitis

25
Q

conjunctival fornix

A

continuous circular cul de sac, broken medially by caruncle and plica

in contact with and adherent to loose fibrous tissue derived from fascial sheaths of levator and recti muscles

superior fornix: 8-10 mm from limbus

inferior fornix: 8 mm from limbus

medially: replaced by caruncle and plica semilunaris
lateral: deep 14 mm from limbus

unites lid and bulbar conjunctiva

lies in a number of folds loosely attached to orbital septum

folds ensure mobility of globe and enlarge secretory surface

26
Q

pseudoglands of henle

A

numerous goblet cells in fornix conjunctiva

27
Q

bulbar conjunctiva

A

thin, transparent, mucous membrane

lies loosely on underlying tissue

3 mm from limbus becomes adherent to sclera and tenon’s capsule

28
Q

some clinical correlates to bulbar conjunctiva

A

chemosis: tissue swelling

subconjunctival hemmorhage

29
Q

limbal conjunctival epithelium

A

bulbar conj. epithelium approaching cornea

of layers: 10 - 15

no goblet cells at limbus

epithelium increasingly similar to corneal epithelium

30
Q

palisades of vogt

A

radially oriented channels within stroma of limbal conjunctiva

stromal channels separated from another by ridges of epithelium

palisades = stromal channels + epithelium (rete pegs) + small nerves, blood vessels, lymphatics run length of papilla

house of limbal stem cells responsible for corneal repair

aka complicated microenviroment = limbal niche

31
Q

malfunction of limbal stem cells proliferation

A

irritable eye, redness, decreased vision, photophobia, tearing, episodes of pain because cornea erosions

slit lamp eval shows dull and irregular corneal reflex: areas of opacification and pannus

impression cytology: presence of goblet cells; absence of differentiation as corneal cells (absence of keratin K3)

32
Q

Conjunctiva glands (3)

A

Glands of krause

glands of wolfring

glands of henle

33
Q

glands of krause

A

accessory lacrimal glands found deep in subconjunctival connective tissue of upper and lower fornix

42 in upper fornix
6-8 in lower fornix

34
Q

glands of wolfring

A

accessory lacrimal glands

2-5 upper lid along border of upper tarsus

2 glands along inferior edge of lower tarsus

35
Q

glands of henle (crypts of henle)

A

secrete mucous

occurs in palpebral conj. between tarsal plate and fornices

not true glands

folds of mucous membranes (lots of goblet cells)

36
Q

caruncle

A

small, pinkish ovoid body in lacus lacrimalis (lacrimal lake) at medial angle of eye

medial to plica

nonkeratinized stratified squamous epithelial

modified skin possessing few fine colorless hairs and sebaceous glands (oil), sweat glands, accessory lacrimal glands

37
Q

plica semilunaris

A

half moon shaped fold

lateral to caruncle

contain goblet cells (like bulbar conj)

highly vascularized

38
Q

arterial supply to conjunctival (2)

A

2 palpebral arches and 1 artery:
peripheral palpebral arch

marginal palpebral arch

anterior ciliary artery

opthalmic artery -> medial palpebral arter -> marginal arterial arch and peripheral arterial arch

ophthalmic artery -> lacrimal artery -> lateral and medial palpebral artery

conj. capillaries non-fenestrated

39
Q

marginal palpebral arch

A

3 mm from free border of eyelid

b/n tarsus and obicularis oculi muscle

arteries on posterior surface of tarsus supply inferior palpebral conj. of superior lid and superior palpebral conj. of inferior lid

40
Q

peripheral palpebral arch

A

supplies superior palpebral conj and superior & inferior conj. fornices

branches of the peripheral arch form the posterior conj. artery to vascularize bulbar conj

41
Q

pericorneal plexus

A

posterior conj. arteries proceed toward limbus => anastomose with anterior conj. arteries

anterior conj. arteries branched from the anterior ciliary artery

posterior and anterior conj. arteries form pericorneal plexus

42
Q

hyperemia

A

conspicuous clinical sign of acute conj. inflammation because dilation of posterior conj vessels

if anterior ciliary vessels are involved, pericorneal area has deeper congestion => hypermia => inflammation in deeper structures (like anterior uvea)

43
Q

hypoyon

A

pus in anterior chamber

44
Q

conjunctival veins

A

accompany conjunctival arteries

drain to: palpebral veins or superior and inferior ophthalmic veins

45
Q

conj. lymph drainage

A

mediation of immunological rxn that occur in diseases

arranged as superficial and deep plexus in submucosa (substantia propria)

lateral -> superficial parotid nodes

medial -> submandibular nodes

viral infection produces lots of lymphocytes -> preauricular will be swollen

46
Q

sensory innervation

A

bulbar conj: long ciliary nerves (nasociliary branch of CN 5)
- unmyelinated nerves

superior palpebral and fornix: frontal branch of CN5 and lacrimal branch of CN 5

inferior palpebral and fornix:

  • lateral: lacrimal branch of CN5
  • medial: infraorbital nerve from CN5 maxillary

Ocular Biology (9 decks)

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