Classification of Dry Eye:
A. Aqueous-deficient:
1. Sjögren syndrome dry eye
2. Non-sjögren syndrome dry eye:
i. Lacrimal deficiency:
- Primary:
- Age-related dry eye,
- Congenital alacrima
- Secondary:
- Acquired immunodeficiency syndrome (aids),
- Lacrimal gland or nerve ablation.
ii. Lacrimal gland duct obstruction:
- Trachoma,
- Chemical injury,
- Stevens–johnson syndrome
iii. Reflex hyposecretion:
- Sensory:
- Contact lens wear,
- Diabetes,
- Refractive surgery,
- Neurotrophic keratitis.
- Motor block:
- Seventh cranial nerve damage,
- Systemic drugs.
B. Evaporative
A. Intrinsic Factors:
- Meibomian gland deficiency, e.g.
- Posterior blepharitis,
- Rosacea.
- Disorders of lid aperture, e.g.
- Excessive scleral show,
- Lid retraction,
- Proptosis,
- Facial nerve palsy.
- Low blink rate, e.g.
- Parkinson disease,
- Prolonged computer monitor use,
- Reading
- Watching television.
- Drug action, e.g.
- Antihistamines,
- Beta-blockers,
- Antispasmodics,
- Diuretics.
B. Extrinsic Factors:
- Vitamin a deficiency.
- Topical drugs including the effect of preservatives.
- Contact lens wear.
- Ocular surface disease such as allergic conjunctivitis.
Causes of Dry Eye:
- Age:
- Over age 65
- Gender- female are more affected due to:
- Pregnancy,
- Oral contraceptives and
- Menopause.
- Medications: can reduce tear production. E.g.
- Antihistamines,
- Decongestants,
- Anti-hypertensive and
- Antidepressants,
- Medical conditions:
- Ocular conditions -
- Inflammation of the eyelids (blepharitis)
- Inflammation of the surfaces of the eye,
- The inward or outward turning of eyelids
- Others conditions:
- Rheumatoid arthritis,
- Diabetes and thyroid problems
- Environmental conditions:
- Exposure : can increase tear evaporation resulting in dry eye symptoms, e.g.
- Smoke,
- Wind and dry climates:
- Failure to blink regularly:
- Using screen for long periods of time
- Other factors:
- Long-term use of contact lenses,
- Refractive eye surgeries (decrease tear production)
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