Eye Disorders I Flashcards
Functions of the lens
• The lens can adapt and change shape (accommodation) in order to change the direction of a light wave (refraction).
This allows us to focus on an image.
• As we get older (usually starting in our 40s), our ability to have our lens change shape weakens.
• This causes us to need reading glasses as we can’t focus on close objects.
• We completely lose this ability when we are about 55-60.
• Then lens also blocks harmful ultraviolet (UV) light from entering the eye
attached to zonules which attach to ciliary bodies
Dry Eye Disease
•Dry eye disease is an multifactorial, inflammatory
disease involving the entire lacrimal
functioning unit.
inflamm involved, dk if it causes it or is caused by dry eye
• Management of the condition mostly focuses on
replenishing the deficient tear layer.
• May not necessarily treat the cause of the inflammation
Components of tears:
- Lipid: Slows down evaporation of tears secreted by Meibomian glands
- Aqueous: Supplies moisture; aka watery component, secreted by lacrimal gland
- Mucin: Coats the eye to allow the aqueous layer to stick to a water repellent cornea
Pathophysiology:
Aqueous-Deficient Dry Eye
Refers to not producing enough aqueous or mucin.
- Type 1: Sjogren syndrome
- Autoimmune disease that involves damage to goblet cells that are involved in tear production (mucin).
- Type 2: Non-Sjogren syndrome
- Primary or Secondary lacrimal gland deficiencies
- Obstruction of lacrimal ducts
- Reflex hyposecretion
Pathophysiology:
Evaporative Dry Eye (EDE)
• Characterized by a high level of tear evaporation
- External
- Environmental Factors
- High temperature or low humidity
- Certain exposures to sun, dust and wind.
• Internal
• Meibomian gland dysfunction
• Chronic inflammation that leads to squamous debris, gland obstruction and
changes in glandular section.
- Intrinsic
- Conditions that affect closing of eyelids or decreased blinking.
• Other Risk Factors
• Thyroid dysfunction, laser eye surgery, medications (oral contraceptives), excessive
digital/screen time
Aqueous or Evaporative Dry Eye: Symptoms
Aqueous and Evaporative dry eye are not separate entities and they
are believed to exist on a continuum.
- The tricky thing is patients may have:
- Symptoms but no physical signs on the eye
- Signs on the eye but no symptoms
- Stinging/ gritty/ scratchy eyes
- Fluctuating vision (intermittent blur)
- Burning or feeling of a foreign body in the eye
- Severe cases: Blurry vision, light sensitivity, excess tear production.
- Over time can lead to inflammation/redness around the eyes
- History/Onset:
- Can develop over days, months or years.
- Sometimes patients get used to the symptoms so symptoms “go away
Management: Non-Pharmacologic
- Education on environmental management
• Using a humidifier or adjusting temperature at home. (winter time due to hea)
• Blinking exercises - Reassessing systemic medications
- Warm Compress
• Using a warm cloth, place over eyelids for 5-10 minutes.
• Patient must keep rewetting cloth; a better solution is a Bruder Mask that stays hot for 10 minutes.
(need to be warmed longer for movement in eyes) - Other: lipiflow, radiofrequency, intense pulse light
Management: Pharmacologic
Artificial Tears
• So many on the market, preferences based on clinician and samples available.
• Preservative containing versus Preservative free.
• Look at the four categories to determine equivalencies between drops.
• Cost
• Viscosity
• Demulcents
• Emollients
Preservative Containing Drops
• The preservative prevents bacterial growth.
• Most common and the cheapest.
mutidose vials, exposed to environment
Preservative Free Minums
• They are usually in vials called minums.
•Can be expensive ($$$)
•Generally recommended if patient requires
frequent drop use (ie. After eye surgery) (more than 4x.day)
one use only
Management: Pharmacologic
• Cost (more important)
- Viscosity agent (more important)
- Determines length of action
- Lower viscosity (Short acting, eye drops)
- Higher viscosity (Long acting, gels and ointments)
- Demulcents (less important)
- Protect and lubricates mucous membranes, relieves dryness.
- Emollients (less important)
- Protect and soften tissues, prevents drying and cracking
Artificial Tears
- Viscosity
- Lower: Eye drops
- Good for all day use.
- Does not disrupt vision after use.
- Needs to be used at an increased frequency.
• Higher: Gels and Ointments
• Better for use at night time or before bed.
• Blurry vision after use.
• Longer lasting type of tear
don’t use with contact lens, smears on lens
Systane Ultra vs Systane Balance vs Systane complete
key diff:
ultra: just aqeious layer (demulcent)
balance: has a lipid component too
Commonly Recommended Gels and
Ointments
• Liposic • Lacrilube • Systane gel ointment • Refresh PM give to pt who sleep with eyes open to shield cornea from drying out
Management: Prescription Medications
• Topical (Ophthalmic) corticosteroids:
- Examples:
- Lotemax/Alrex (Loteprednol 0.5%)
- FML (Fluorometholone 0.1%)
• Mechanism of Action:
• Anti-inflammatory corticosteroid. Inhibits inflammatory processes
and mediators of inflammation.
• *Dose and length of therapy is dependent on the diagnosis and
steroid chosen–> commonly tapered but not always
- Adverse Effects: Blurred vision, photophobia, burning/stinging
- Length of Therapy: 14 – 28 days
- Onset of Effect: Generally would expect benefit within a week
NSAIDS do not work for DED, rsiks of integrity of cornea
