Week 9: Dry Eyes

What is the composition and function of tear film?

What is the composition and function of tear film?

• Two layers: lipid and combo of aqueous and mucous layer

• fxn: hydration, lubrication, oxygen + nutrition for cornea, removal of debris

  Antimicrobial, Smooth surface

What does the ocular surface consist of?

cornea and conjunctiva

Cornea

Transparent dome-shaped tissue that has no blood vessels and allows light to enter the eyeball to stimulate rods and cones in retina -> able to see

Conjunctiva

Thin transparent membrane covering the inside of eyelids and top of sclera

Lipid layer secreted by?

• Meibomian glands (inside eyelid) 

• Gland of Zeiss and Moll (base of each eyelash)

Aqueous  layer secreted by…

• Lacrimal glands (above each eyeball)

• Glands of Krause and Wolfring (under the eyelids)

Mucous layer secreted by….

• Goblet cells (conjunctiva)

• Corneal and conjunctival epithelial cells (outermost layer of cells on cornea and conjunctiva)

Label the glands/structures

1. Lacrimal gland

2. Meibomian gland

3. N/A

4. Corneal and conjunctival epithelial cells

Label the glands/structures

1. Meibomian gland

2. Glands of Moll

3. Glands of Zeis

What are the non-modifiable risk factors for dry eyes?

• Age : incr w/ age (> 65 yo, 15%)

• Female Sex (> 50 postmenopausal women)

What are the modifiable risk factors for dry eyes?

• Systemic dz

  • Autoimmune disorders: Sjorgen’s syndrome, RA, Lupus, Rosacea

  • Endocrine disorders: DM, Grave’s Dz

• Local eye conditions

  • Blepharitis, Multiple Sclerosis, Eye, Lid defects

• Medications

  • Diuretics, B blockers, Antihistamines, Anticholinergics (scopolamine, some meds for psych), Antipsychotics, Benzodiazepines, some analgesics, Vit A

• Environment

  • Dry, Dusty

• Lifestyle

  • Excessive use of computer or other screens, Smoking, alcohol

What characteristics with the eye are considered referrals?

• Red eye w/ pain, blurred vision, acutely inflamed eyelids

  • angle closure glaucoma

  • keratitis

  • uveitis (inflammation inside eye)

• Discharge and matty lids (crusty, sticky layer of mucus)

  • conjunctivitis (viral/mucopurulent or bacterial/less mucopurulent)

Regarding timing of sx, what would constitute a referral?

Sudden onset of sx w/in past few hours/days

What is the active ingredient class called in artificial tears?

demulcent (water-soluble polymer)

What are the 4 types of demulcents?

1. cellulose derivatives

2. polyols

3. alcohols

4. dextran 70 (used in combo)

What are the different types of cellulose derivatives?

1. Carboxymethylcellulose (CMC)

2. Hydroxypropyl methylcellulose (HPMC, Hypromellose)

What are the different type of polyols?

1. Propylene glycol

2. polyethylene glycol

3. glycerin

4. polysorbate 80

What are the different types of alcohols?

1. Polyvinyl alcohol

2. Povidone

What are the inactive (universal) ingredients?

1. NaCl, KCl, MgCl2, Phosphate/Bicarbonate based sulfur

2. Osmoprotectants

3. Humectants

4. Hydroxypropyl guar gum

5. Ingredients that prevent of water evaporation

MOA and types of osmoprotectants

1. Protect cells against hyperosmolarity-med injury

2. Trehalose, Carnitine, Erythritol

MOA and types of humectants

1. Absorb and retain water

2. Sodium hyaluronate

MOA of Hydroxypropyl guar gum

Mucin mimetic action

What are the ingredients that prevent water evaporation?

Oils (castor oil, flaxseed oil, mineral oil)

What are the types of vanishing preservatives?

1. Purite: oxychloro complex containing 99.5% chlorite, 0.5% chlorate

   1. Upon instillation, light breaks it into sodium chloride, O2, H2O

2. Sodium perborate (Dequest)

   1. Upon instillation, light breaks it down to low levels of H2O2

What are the types of Quaternary ammonium compounds?

1. Polyquaternium-1

   1. high molecular weight quaternary ammonium compound w/ microbicidal activity but has very low toxicity to corneal/conjunctival epi cells

2. Benzalkonium Chloride (BAK)

   1. High molecular weight quaternary ammonium compound 

   2. Toxic to corneal/conjunctival epithelial cells

   3. AVOID eye drops in pts of dry eye

What is a similarity with all preservatives? (and which eye drops contradict this similarity?)

pH neutral (except Thera tears which is hypotonic)

What are counseling points regarding Preservative-Free Single Dose Unit eyes drops?

1. can use multiple times in a SINGLE DAY, discard at the end

2. pt advised to keep in a cool place (refrig) and not touch the tip by hand or other object

How often should preservative-containing articifical tears be used?

4-6 times/day

If the patient needs to use eye drops 6 or more times a day, what should they use?

unit dose single use eye drops

When should a pt discard a multidose vial after opening?

after 30 days

Is dry eye disease chronic or acute?

chronic (should use artificial tears as sx improve and to sustain improvement)

For Mild cases of dry eyes, what should be recommended?

CMC or HPMC-based tears with lifestyle changes

If you have already recommended a CMC or HPMC-based tears and lifestyles changes, what is the next step if the pt still complains of dry eyes?

increase freq (4-6 for preservative-based, ≥ 6 for preservative free)

If already increased frequency, what is the next step if the pt still complains of dry eyes?

tears w/ multiple active ingredients (esp lipid component)

• CMC + (Trehalose, hyaluronic acids, oils, glycerin, polysorbate)

• switch to polyols-containing tears (guar gum, mineral oil)

If already recommend tears w/ multiple active ingredients (esp lipid component), what is the next step if the pt still complains of dry eyes?

1. consider referral (if sx do not improve/worsen)

2. add gel-based tears

3. supplement w/ nighttime ointments

What is not recommended for dry eyes?

Vascoconstrictors

• tetrahydrozoline, nephazoline, phenylephrine

  • Visine, Clear Eye

Why are vasoconstrictors not recommended?

• rebound increase in redness

• tolerance + pt ends up using more freq

• ocular surface damage (preservatives)

• vascular fragility

Artificial Tear Inserts are prescription only, what is the product and its limitations?

Lacrisert

• water soluble rod + hypromellose

• swells up and dissolves

• Limits:

  • expulsions, vision blurring

  • does not work in pts w/ low tear secretion

Why are ointments recommended?

NIGHT-time use only since they interfere w/ vision (mineral oil, white petrolatum)

• tak contact lenses OFF

• close eyes for 2 min

MOA of punctal plugs

• Prevent the tear outflow, thus retaining the tear film

• Inserted under topical anesthesia using jeweler's forceps either into punctum or canaliculus

What are the two types of materials punctal plug?

silicone and collagen

What are the limitations to punctal plugs?

1. spontaneous extrusion

2. replacement has higher rate of expulsion

What products inhibit ocular surface inflammation?

1. cyclosporine (Restasis)

2. liftergrast (Xiidra)

How is cyclosporine (Restasis) provided?

ophthalmic emulsion in a single unit vial

What is the response of the guy by ophthalmic response to cyclosporine?

• decreases ocular surface inflammation and increases tear production

• Instill one drop twice daily in the affected eye

• Indicated for moderate to severe dry eye

What are the side effects of cyclosporine (Restasis)?

• burning sensation upon instillation (most common)

• conjunctival hyperemia, discharge, eye pain, foreign body sensation, pruritus, stinging, blurring (in 1-5% pt)

Counseling points regarding cyclosporine (Restasis)

1. invert bottle few times b4 admin

2. allow min of 15 min interval between instillation of cyclosporine and artificial tears or other eye drops

3. not to use while wearing contact lenses; REMOVE PRIOR

   1. re-insert 15 min after instillation of drops

How is Lifitegrast (Xiidra) provided?

5% opthalmic solution in a single unit vial

MOA of Xiidra

1. lymphocyte fxn-associated antigen-1 (LFA-1) antagonist

2. decr ocular surface inflammation

Instill 1 drop BID

What are the side effects of Xiidra?

blurred vision, conjunctival hyperemia, eye irritation, headache, incr lacrimation, eye discomfort, eye pruritus

Counseling points for Xiidra

• allow min of 15 min interval btwn instillation and artifical tears or other eye drops

• not to use while wearing contact lenses

  • remove PRIOR to admin → re-inserted 15 min after instillation of drops

What are the products that stimulate tear secretion?

1. pilocarpine

2. diquafosol (Diquas)

What is the difference in MOA between pilocarpine and diquafosol?

Pilocarpine stimulates lacrimal, krause, and wolfring glands whereas Diquas stimulates goblet cells and accessory glands