Dry Eye - Clinical Features & Investigation 3/4

Clinical features

Symptoms:

• Feelings of dryness, grittiness and burning that characteristically worsen over the course of the day
• Stringy discharge, transient blurring of vision, redness and crusting of the lids are also common
• Sensitivity to light, difficulty with nighttime driving
• Foreign Body (FB) sensation
•  Watery eyes, which is the body's response to the irritation of dry eyes
• Lack of emotional or reflex tearing is unusual

Signs:

In Eyelid:

• Posterior (seborrhoeic) blepharitis with meibomian gland dysfunction is often present.

In Conjunctiva:

• Redness.
• Staining with fluorescein and rose bengal
• Keratinization.
• Conjunctivochalasis: non-edematous excess fold in the conjunctiva

In Tear film:

• In the normal eye;
• As the tear film breaks down the mucin layer becomes contaminated with lipid but is washed away.
• In the dry eye;
• The lipid-contaminated mucin accumulates in the tear film as particles and debris that move with each blink.
• The marginal tear meniscus (strip):
•  In the normal eye the meniscus is 0.2–0.4 mm in height, but in dry eye becomes thin or absent.

In Cornea:

• Punctate epithelial erosions
• Stain well with fluorescein.
•  Filaments;
• Stain well with rose bengal but less so with fluorescein.
• Mucous plaques:
• Occur in severe dry eye. They consist of semi-transparent, white-to-grey, often slightly elevated lesions of varying size.

Investigation

• There is no clinical test to confirm the diagnosis of evaporative dry eye, diagnos is based on the presence of associated clinical findings.
• The aim of investigation is to confirm and quantify a clinical diagnosis of dry eye. 
• The tests measure the following parameters:
• Stability of the tear film: 
• Tear break-up time (but).
• Tear production
• Schirmer Test, 
• Fluorescein clearance and 
• Tear osmolarity
• Ocular surface disease
• Corneal stains and 
• Impression cytology

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