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OPTO3003 > W3 DED > Flashcards

W3 DED Flashcards

1
Q

Layers of tear film:

A

Lipid
Aqueous
Mucous
Glycolax
Ocular surface

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2
Q

Lipid layer:

A

Thin outer meibum layer from sebaceous glands in tarsal plate (Meibomian glands) secreted during blink
Prevent evapouration, acts as surfactant (spreads film)
Non-polar cholesterol, esters, phospholipids, alcohols

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2
Q

Aqueous layer Components:

A

Water, electrolytes, proteins, growth factors, pro-inflammatory interleukin cytokines (accumulate during sleep), Lysozyme, lactoferrin, urea, glucose, ions (Ca/Mg/Na/K), IgA

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3
Q

Aqueous layer formation:

A

97% of film from lacrimal gland (95%) / Krause & Wolfring
From inner/upper lid

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4
Q

Aqueous layer function:

A

O2 > Cornea
IgA / Lactoferrin / Lysozyme > Antimicrobial activity
Maintain moisture of non-keratinized corneal epith.
Leukocyte transport after injury
Smoothens optical surface
Flushes debris

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5
Q

Mucin layer composition

A

Thinnest layer of mucus from goblet cells in conj. / plica semilunaris / glands of henle & Manz
Hydrophilic High mol. Wgt. Mucin glycoproteins (transmembrane or secretory)
Transmembrane mucins bind glycolax from corneal epith.
Secretory are soluble in aqueous forming gel

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6
Q

Types of mucins:

A

MUC1/4/16: membrane bound, with galectin glue to glycolax
MUC7 / MUC5AC: secretory to prevent strands of mucous (light scatter)

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7
Q

Mucin layer function

A

Turns hydrophobic corneal epith. Hydrophilic > corneal wetting
Attaches film to cornea, allows lubrication

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8
Q

Lacrimation reflex:

A

Stimulation > CN5 sensation > brainstem > parasympathetic nucleus of CN7 / sympathetic of medulla > lacrimal gland / spinal cord > lacrimal gland

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9
Q

Definition of dry eye disease (DEWS 2):

A

Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles

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10
Q

Causes of ADDE:

A

Sjrogren’s syndrome (autoimmune against exocrine glands)
Lacrimal gland dysfunction: Primary (age/genetics) or secondary (AIDS/Lymphoma)
Lacrimal gland duct obstruction
Alteration in stimulation (reflex block)

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11
Q

ADDE from secretion stimulation alteration:

A

Reflex hyposecretion from reflex sensory block (CLs/LASIK/herpes/diabetes) or reflex motor block (CN 7 lesion)
Blockage of para/sympathetic nerves to lacrimal gland
Decreased androgen from hormone loss (age)
Exposure to anti depressants/histamines

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12
Q

Causes of EDE:

A

MGD
Infrequent blink
Environment
Ectropion / lagopthalmos
CLs via lipid layer loss
Mass lesions
Vit A def.
Defective mucins (infection)

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13
Q

Meibomian gland dysfunction causes:

A

Drop out (age>50)
Gland replacement (Distichiasis)
Hypersecretory glands (Seborrhea / retinoid therapy)
Gland obstruction
Glaucoma medication (pilocarpine)

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14
Q

Types of MGD:

A

Primary (age/acne): increased bacterial lipases > meibum cleavage > fatty acid formation > increased melting point > hardening
Secondary: diseases
Cicatrical: hyposecretion from damage / steven-johnson syndrome / allergies

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14
Q

hyperosmolarity

A

Loss of aqueous or evaporation > hyperosmolarity > epithelial irritation > Mitogen-activated protein kinase (MAPK) & NFkB activation > inflammatory mediator release (IL-1 & TNF-1/MMPs) > Matrix metalloproteinases damage epithelium / goblet cells > epitheliopathy (corneal epithelium loss) > pain > reflex stimulation
ADDE > lack of watering > further hyperosmolarity
EDE > poor lipid layer > watering

14
Q

Tear film instability:

A

Damage to goblet cells > glycolax/mucin dysfunction > friction on bling > discomfort/inflammation > hyperosmolarity

15
Q

DED symptoms:

A

Pain/burn/grit/FBF
Watering (CN6 activation)
Hyperemia
Lid fatigue
Intermittent blur (better on blink)
Struggle on screen use (blink rate 11/m > 4/m)

16
Q

Slit lamp examination of DED:

A

Lid hyperemia
Tear film debris
Conj. Hyperemia
SPEE (superficial punctate epithelial erosions)
Meibomian capping (MGD/bleph.)
Tear meniscus (reduced in ADDE)

17
Q

Sodium Fluroescein function:

A

NaFl peak absorption at 493nm (blue), emits 520(green), instilled via strip (1% drop), viewed via wratten #12 (yellow-green) filter
Hydrophilic (doesn’t pass lipid bilayer epithelium or tight junctions), pools in corneal/conj. Areas of cell loss

18
Q

Analysis via NaFl:

A

TBUT
Epithelial damage
Papillae/follicle assessment

19
Q

Rose bengal and lissamine green:

A

Binds to damages cells which no longer secrete protective mucins.
Bengal is toxic, lissamine is not painful.

20
Q

Staining patterns in DED:

A

Interpalpebral staining of ocular surface > DED
Sup. Conj. Stain > sup. Limbic keratoconjunctivitis
Inf. Corneal / conj. > poor blink exposure / blepharitis

21
Q

Grading conj./corneal stains:

A

CCLRU grading:
Type/area (2>1>3^4≥5)
Depth
Extent
Conj. Staining

22
Q

Schirmer test:

A

5mm fold in Whatman filter inserted under lower lid (temporal side), don’t touch cornea/lash
Px closes eyes over filter
Remove paper after 5min
<10mm without anesthesia / <6 with ana. Indicates abnormal

23
Q

TFBUT:

A

NaFl instilled with Wratten #12 cobalt filter lens
Px blinks before holding eyes open
Timed appearance of black spots
<10s abnormal, repeated breakup in given area indicates localized surface abnormality

23
Q

Ocular protective index:

A

TBUT/time between blinks: <1 indicates oculur surface exposure

24
Q

Other diagnostic tests for DED:

A

Osmolarity (>317mOsm/L)
Phenol red (pH dye on string like schirmers)
Lactoferrin test (lacrimal Gland production)
Meibometry
Impression cytology (goblet population)

25
Q

DED severity classification:

A

Incresing degrees of symptoms from level 1-4:
Discomfort, visual symptoms, Conj. Injection, conj. Staining, corneal staining, corneal damage, tear film stability (debris/meniscus/mucus clumps), lid/meibomian health, TFBUT (>10, <10, <5, <2), schirmers (>10, <10, <5, <2)

25
Q

Goals of DED management:

A

Eliminate exacerbating factors
Lubricate ocular surface
Minimize exposure
Restore normal osmolarity
Prevent inflammatory mediator/enzyme production
Improve film stability

26
Q

Eye drop preservatives:

A

BAK: toxic to cell junctions / microvilli > necrosis of outer epith.
Disodium (EDTA): stronger (less needed)
Polyquad: less toxic
Sodium chlorite: degrades to Cl- / water via UV
Sodium perobate: converts to water / O2 on contact with tear film

27
Q

Electrolyte function in lubricating drops:

A

K+: maintains corneal thickness
Bicarbonate: maintains epith. Ultrastructures (mucin layer) / ^recovery of epithelial defence
Hypotonic: decrease osmolarity (TheraTears)

28
Q

Compatible solutes in lubricating drops:

A

Glycerin, erythritol, levocarnitine: distribue between intracellular fluid to protect epith.

29
Q

Viscosity agents in lubricating drops:

A

Increase tear residency and protects damaged epith.
Hydroxypropyl(HP)-guar: gel with glycol 400 / propylene glycol
Hyaluronic acid
Polyvinyl alcohol
Carmellose (CMC)
Hydroxymethylcellulose (HPMC)

30
Q

Blepharitis:

A

Lid inflammation from Staphyloccal or dermatitis
Ant. Affects zeis glands/lash follicles (crusty scales) > bleph debris decreases tear quality
Pos. affects meibomian glands (meibum capping) > EDE + inflammatory mediator passage from lid

31
Q

Blepharitis management:

A

Ant. > lid scrubs decrease bac. Load or 1/3 shampoo
Pos. > warm compress + massage > melts meibum caps and expresses

32
Q

Punctal occlusion:

A

Temporary plugs: dissolve in 2w
Prolonged: removed in 6m (risks granuloma)
Permenant occlusion: opthal for cautery

33
Q

Anti-inflammatory treatment of DED:

A

Fluromethalone alcohol/acetate (FML/Flarex): 0.1% qid > 1week with lubricants
Topical ciclosporin (cequa/ikervis): 0.05% bid for ADDE, reduces T-cell inflammation (requires oxford grading scale = 4)
Topical lifitegrast (Xiidra 5%): lymphocyte function-associated antigen (LFA-1) antagonist, blocks LFA-1 on lymphocytes from intercellular adhesion molecule-1 (ICAM-1) on epith.

34
Q

Uncommon DED treatments:

A

Manuka honey
Systemic tetracyclines: alters meibum for rosacea/bleph.
Omega 3 fatty acid supp.: decreases inflammation systematically
CLs: occlusive GP scleral CLs provide saline reservoir
Lacrisert: plastic insert placed in lower lid to hold artificial tears
Palpebral tarsorrhaphy: stich lids closer together

OPTO3003 (18 decks)

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