Dry Eye Syndrome

Kelas tuk hari ni ( berangan lebih ni, dh lama tak teaching)..

So come we study this syndrome.. :)

DRY  EYE

SYNDROME

What are the symptoms?

• Conjunctival hyperemia
• Burning sensation
• Feeling of stand or grit in the eyes
• Mucous discharge
• Increased awareness of lid movement
• Transient blurring of vision relieved by blinking
• Itch

What causes dry eye?

The tear film, ocular surface, eyelids and the action of blinking are critical for maintaining the health of ocular surface. Hence, any dysfunction or disruption of these elements can lead to an abnormally of the ocular surface and to dry eye symptoms.

Dry eye signs and symptoms can also result from abnormalities of any layer(s) of the tear film.

Other specific causes of dry eye include:

1. Environment
   Airborne pollutants, haze and smoke often irritate our eyes. The low humidity in air-conditioned rooms is another common cause of dry eye.
2. Age
   Tear flow rate and the quality of tears decrease as we grow older. Dry eye is also more common in postmenopausal female.
3. Contact Lenses
   Contact lens wear associated with poor blinking mechanism or poor tear quality with result in dry symptoms.
4. Visual Tanks
   Prolonged staring at computer terminals and television screens decrease the frequency of blinking and set the stage for dry eye.
5. Others
   Certain systemic medications such as anticholinergics, diuretics, antihistamines and decongestants can cause decreased aqueous tear secretion.
   
   Diseases such as rheumatoid arthritis and Sjogren's syndrome can also cause dry eye.

Diagnosis

Upon asking the complete history of the symptoms, three simple investigations can be used to help establish the diagnosis.

1. Schirmer Test
   
   Principle: Standardized strips of filter paper dipped into the tear film soak up the length of filter  paper    wetted over a set period gives an indication of the rate of tear production.
   
   Interpretation of results:
   More than 15mm wetting in 5 minutes = Normal
   6 to 15mm wetting in 5 minutes = Suspicious
   Less than 6mm wetting in 5 minutes = Abnormal
2. Rose Bengal Staining
   
   Principle:Rose Bengal, a dye related to fluorescein, stains dead or drying cells on the ocular surface and the mucus in the tear film. Following a drop of topical anaesthetic, a drop of Rose Bengal is instilled. Staining is observed using a hand lens or ophthalmoscope after asking the patient to blink several times. One is looking for multiple spots of deep pink stain on the inferior half of the cornea and the adjacent bulbar conjunctiva.
   
   Interpretation of results:
   If there is obvious staining of the cornea and the nasal, temporal and inferior conjunctiva, this test has a sensitivity and specificity for dry eye of  > 90%.
   
   If the results of the Schirmer test and Rose Bengal staining indicate dry eye, topical lubricant is certainly indicated.
3. Tear Film Break-Up Time (BUT)
   
   Principles: BUT assesses the function of tear film mucin. The longer the BUT - the more stable the tear film is. Fluorescein dye is applied to the eye and patient is asked to close the eyes for 20 seconds. Upon opening, the time before any dry spot appear will be the BUT.
   
   Interpretation of results:
   BUT > 15 seconds = Normal
   BUT > 10 Seconds = Abnormal

What are the treatments?

Artificial tear preparations

Artificial tears restore the volume of the precorneal tear film.

Ophthalmic ointments

 Ointments have prolonged retention time. They are for bedtime use so as to keep the eye moist throughout the night.

Education of the patient

 The patient must understand that treatment must be continuous and prolonged. Patient should be encouranged to use their drop frequently (about 2-3 hourly) at first and subsequently to slowly reduce the frequency until the control of the symptoms can just be maintained.

When dry eye symptoms become so severe that frequent instillation of artificial tears do not provide adequate relief, occlusion of the lacrimal puncta or eyelid surgery may be necessary.

What is tear film?

The precorneal tear film is composed of three layers. The outer most lipid (or oily) layer is secreted by the meibomian glands. This layer decreases evaporation of and provides biochemical stability to the tear film.


The middle layer and the thickest, is the aqueous layer. This layer which comprises over 90% of the tear volume is secreted by the lacrimal and accessory lacrimal glands. It contains electrolytes, trace elements and proteins.


The innermost layer is the mucin layer. Mucin is secreted by goblet cells located on the conjunctival surface. Mucin allows adherence of the hydrophilic aqueous to the hydrophobic epithelium.