Dry Eye

Question 1

What is KCS

Answer 1

refers to any eye with some degree of dryness.

Question 2

What is Xeroophthalmia

Answer 2

describes a dry eye associated with vitamin A deficiency.

Question 3

What is Xerosis

Answer 3

the extreme ocular dryness and keratinization that occurs in eyes with severe conjunctival cicatrization.

Question 4

What are the tear film constituents

Answer 4

Lipid layer secreted by the meibomian glands. Aqueous layer secreted by the lacrimal glands.
Mucous layer secreted principally by conjunctival goblet cells. The constituents are complex, with as many as a hundred distinct proteins identified.

Question 5

What is the outer lipid layer of the tear film composed of

Answer 5

polar phase containing phospholipids adjacent to aqueous- mucin phase and a non polar phase containing waxes, cholesterol esters and triglycerides

Question 6

What % of tears is aqueous

Answer 6

95%

Question 7

Which glands produce aqueous

Answer 7

Lacrimal 95%
Krause and Wolfring remainder

Question 8

What is the composition of the mucous layer of tear film

Answer 8

mucins high molecular weight proteins. Convert hydrophobic corneal epithelium to hydrophilic allowing wetting

Question 9

Which conditions can result in goblet cell loss from the tear film

Answer 9

cicatrizing conjunctivitis
vitamin A deficiency
Chemical burns
toxicity from meds

Question 10

What are the 2 ways we get regulation of tear film components

Answer 10

Hormonal- androgens prime hormones for regulation of lipid production. Oestrogen + progesterone essential.
Neural- fibres adjacent to lacrimal glands and goblet cells which stimulate aqueous and mucous secretion

Question 11

What 4 core inter related mechanisms are responsible for dry eye

Answer 11

tear instability
tear hyperosmolarity
inflammation
ocular surface damage

Question 12

What are some causes of aqueous deficient dry eye

Answer 12

Sjogren syndrome dry eye
Lacrimal deficiency primary or secondary inflammatory/neoplastic lacrimal gland infiltration. AIDS, gVHD, Lacrimal duct obstruction trachoma, cicatricial pemphingoid, chemical injurym SJS
Reflex hyposecretion CL wear/diabetes/refractive surgery/ neurotrophic keratitis

Question 13

What are the causes of evaporative dry eye

Answer 13

Intrinisic- MGD/ Disorders of lid aperture, Low blink rate, drugs like antihistamines, beta blockers, antispasmodics, diuretics
Extrinsic- Vit A deficiency, Topical drus + preservatives
CL wear, allergic conjunctivitis

Question 14

What is Sjogren syndrome

Answer 14

autoimmune disorder with lymphocytic inflammation + destruction of lacrimal and salivary glands + other exocrine organs
Triad: dry eyes dry mouth parotid gland enlargement

Question 15

What is the ACR criteria for diagnosis of Sjogren syndrome

Answer 15

Positivity for anti-SSA or anti- SSB antibodies or positive RF + positive ANA
Ocular staining above a certain grade
Focal lymphocytic sialadenitis

Question 16

What are some treatments for Sjogren syndrome

Answer 16

oral pilocarpine immunosuppression, biological blockers like rituximab

Question 17

What are some signs/symptoms of Sjogrens syndrome

Answer 17

dryness
grittiness
burning
stringy discharge
posterior blepharitis
red eye
staining with rose bengal and lissamine green
keratinization
conjunctivochalasis
Reduced marginal ear meniscus <0.25mm
PEE’s, filaments on cornea

Question 18

What is normal tear film meniscus

Answer 18

0.2-0.4mm
Dry eye <0.25mm

Question 19

What is an abnormal TBUT

Answer 19

<10 seconds

Question 20

What does the Schirmer test measure

Answer 20

aqueous tear production

Question 21

Principles of Schirmer test

Answer 21

measuring the amount of wetting of a special (no. 41 Whatman) filter paper, 5 mm wide and 35 mm long.
The test can be performed with or without topical anaesthesia.

Question 22

How is the Schirmer test done

Answer 22

Excess tears dried. If topical anaesthetic applied, excess removed from inferior fornix
Filter paper folded 5mm from one end and inserted at the junction of middle/outer third of lower lid. Keep eyes gently closed. After 5 minutes the filter paper is removed and amount of wetting from the fold measured
<10mm wetting after 5 mins without anaesthetic or <6mm with anaesthesia is abnormal

Question 23

What are some ocular surface stains

Answer 23

Fluorescein- corneal/conj epithelial stain
Rose bengal- affinity for dead/devitalized epithelial cells. Corneal filaments/plaques more clearly.
Lissamine green- similar to Rose bengal but less discomfort

Question 24

What are some patterns of corneal staining to aid diagnosis

Answer 24

Interpalpebral: aqueous tear deficiency
Superior conj stain: SLK
Inferior corneal/conj stain: blepharitis/ exposure

Question 25

What is normal tear film osmolarity

Answer 25

308mOsm/l

Question 26

What does impression cytology in dry eye disease measure

Answer 26

goblet cell numbers

Question 27

What are level 1 treatment strategies for dry eye

Answer 27

Education/ Environment/ Dietary modifications Systemic medication review Artificial tear substitutes + gels/ ointments/ Eyelid therapy

Question 28

What are level 2 treatment strategies for dry eye

Answer 28

Non preserved tear substitutess Anti inflammatory agents like topical steroids Tetracyclines Punctal plugs Secretagogues Moisture chamber spectacles

Question 29

What are level 3 treatment strategies for dry eye

Answer 29

Serum eye drops (Autologous/ umbilical cord serum) Contact lenses Permanent punctal occlusion

Question 30

What are level 4 treatment strategies for dry eye

Answer 30

Systemic anti inflammatory agents Surgery: tarsorrhaphy, salivary gland auto transplantation, mucous membrane, amniotic membrane transplant

Question 31

Who is punctal occlusion good for

Answer 31

patients with moderate- severe KCS not responded to topical agents

Question 32

What are some anti inflammatory agents useful in dry eye

Answer 32

Topical steroids like FML Omega 3 fatty acids/ flax seed oil PO tetracyclines for 3 months at low dose. Topical ciclosporin reduce T cell mediated inflammation of lacrimal tissue

Question 33

What is Cenegermin 0.002%

Answer 33

topical recombinant human nerve growth factor (use in neurotrophic keratopathy) for severe Sjogren syndrome.

Question 34

What is photobiomodulation therapy

Answer 34

low level light/ red light and IPL new options useful for dry eye secondary to severe MGD