Dryness in the eye, burning sensation leads to a mild decrease in vision and sometimes excessive tearing which is often excaberated by smoke, wind, heat, low humidity or prolonged use of mobile phones or computers is something you face?
And is it causing an immense problem to your day-to-day lifestyle?
You might be having something called as a Dry eye syndrome.
The above-mentioned problems are the most common symptoms of dry eye syndrome.
So what is a Dry eye syndrome?
There lies a tear film superficial to our cornea this tear film comprises three different layers namely a lipid layer on the top, an aqueous layer in the middle, and a mucus layer in the bottom just above the cornea.
The lipid layer prevents quick evaporation of the tear and it is secreted by the Meibomian glands
The aqueous layer contains electrolytes for the nourishment of the cornea and is secreted by the lacrimal glands, Glands of Krause and Wolfring
The mucus layer helps in adhering that tear film with the corneal epithelium and is secreted by the Goblet cells
Now abnormalities in any of the three layers can cause hindrance in the corneal physiology, redness in the eye, etc. and thereby cause Dry Eye Syndrome
These abnormalities in the layers can be caused Due to certain factors:
Local inflammation in the eye
Inflammation In the glands secreting the various layers of the tear film
An eye infection
Dehydration, etc
Signs your optometrist will see in your eyes during examination are as follows:
Less than normal meniscus in the inferior lid margin
a decreased Tear breakup time
Maybe a conjunctival or corneal staining
Excess mucus or debris in the tear film in severe cases
This syndrome can either be associated with:
Idiopathic( something not so specific/unknown)
Connective tissue diseases eg: Sjogren Syndrome, rheumatoid arthritis, systemic lupus erythematous
Conjunctival scarring
Various Keratopathies
Influence of some drugs eg, oral contraceptives, antihistamines, atropine
There are certain special clinical tests done to confirm a dry eye syndrome :
Vital Dye Staining
Fluorescein (2%) staining: It stains precorneal tear-film and intercellular tissue. It does not stain the mucus and devitalized epithelial cells.
Rose-Bengal (1%) staining: It has an affinity for devitalized epithelial cells, mucus, and filaments. It is very useful to detect mild cases of dry eye by staining the interpalpebral conjunctiva in the form of two triangles with their bases towards the limbus. Topical anesthesia should not be used prior to Rose-Bengal staining, as it may induce false-positive results.
Alcian blue staining: It is used to stain the mucus more selectively.
Fluorescein Staining((Source: Essentials of Ophthalmology by SK Basak)
Tear-Film Break-up Time
It is a simple test to assess the stability of the precorneal tear film.
A drop of fluorescein is instilled and the patient is asked to blink 2–3 times to
distribute the dye.
The patient is then asked not to blink while the cornea is studied by the cobalt blue
filter with the slit lamp.
The tear-film break-up time (TBUT) is the time in seconds between the last blink and the appearance of dry (black) spots on the cornea.
A normal TBUT is more than 10 seconds(11 to 35 seconds), and a TBUT value less than 10 seconds is abnormal.
Schirmer’s Test
A 5 mm wide and 35 mm long special filter paper is placed in the lower fornix at the junction of the middle and outer third of the eyelid after folding it at 5 mm. After 5 minutes, the amount of wetting from the fold is measured. The patient may blink or close his eyes as necessary during the test.
Schirmer’s Test (Source: Essentials of Ophthalmology by SK Basak)
Some Laboratory Tests which can also be conducted are:
Tear lysozyme assay
Tear osmolarity
Conjunctival impression cytology
Goblet-cell count of the conjunctiva
Treatment
There is no permanent cure for dry eye, but there are some options available to relieve symptoms:
Preservation of the existing tears
Reduction of the room temperature.
Humidifiers: Examples are swimmer’s goggles, moist-chamber goggles, etc.
Plenty of intake of drinking water.
Lid taping and tarsorrhaphy to prevent exposure to keratitis.
Punctal occlusion: It is to preserve the natural or artificial tears in contact with
the ocular surface for a longer time.
CMC Artificial Eye Tear Drops
Supplementation of tears: Essentially four types of tear substitutes are currently available in the market. The composition of tear substitutes are cellulose (methylcellulose, hydroxypropyl methylcellulose, hypermellose), polyvinyl alcohol, povidone, and sodium hyaluronate. They are used either alone or in combination.
Drops: Frequency of installation may vary with the severity of dry eye 4 times/
daily to the half-hourly interval.
Ointments: Petroleum mineral oil or jelly is used at bedtime as an ointment.
Slow-releasing inserts (ocusert): Lacrisert, formerly known as SRAT (slow-releasing artificial tear), is a small 5 mg pellet of hydroxypropyl cellulose in a cylinder form. It is placed in the lower fornix once daily. It dissolves slowly and releases its polymer into the tear film. Inadvertent loss of insert and blurred vision are common problems.
Gel-tears: The gel is a clear synthetic polymer of acrylic acid which dissolves very slowly. It persists in the conjunctival sac for several hours after installation. Temporary blurring of vision may be a problem.
(Source: Essentials of Ophthalmology by SK Basak)
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