DRY EYE SYNDROMES
They are the conditions in which there is defective wetting of the conjunctiva and cornea by tears making then dry and lustreless.
Types and etiology:-
1. Deficiency of the watery component of tears (Kerato-conjunctivitis sicca):
This syndrome occurs due to destruction of the main and accessory lacrimal glands. The causes of this syndrome are:
- Autoimmune destruction is the commonest cause, and it is usually bilateral and complete. It can be either:-
a. Isolated lacrimal glands destruction.
b. As a part of Sjograen syndrome (dryness of the eye, mouth, bronchial secretions, dry vulvo-vaginitis and poly-arthritis).
- Partial dryness (only lack of reflex lacrimation) occurs in cases of:-
a. Facial nerve lesions.
b. Surgical excision of lacrimal gland.
In these cases the accessory lacrimal glands will maintain the basal tear secretion.
2. Destruction of goblet cells (Xerosis):
Mucin is important for spread of watery tears over the surface of conjunctiva and cornea. So that deficiency of mucin causes dryness. Atrophy of goblet cells occurs in cases of:-
1. Local causes:-
a. Conjunctival scarring due to: - Healed trachoma
- Chemical burns.
- Membranous conjunctivitis.
b. Exposure and lagophthalmos.
2. Vitamin A deficiency due to: - Decrease intake (rare).
- Increased demand as lactation.
- Malabsorption syndromes.
- Burning sensation and sense of dryness.
- Photophobia if the cornea is affected.
- Loss of lustre of cornea and conjunctiva.
- Conjunctiva is injected and wrinkled.
- Increased debris in tears.
- Special signs in sicca syndrome:-
1. Punctate staining of the exposed part of bulbar conjunctiva by rose bengal.
2. Schemer test I & II show decreased watery tear production:-
- Local anaesthesia is instilled.
- 5 mm of the Schemer test paper (5 X 35 mm) is inserted in the lower fornix at the junction between outer third and inner thirds of the lower lid. It is left for 5 minutes to absorb tears by capillarity.
- Normally 10 - 25 mm of the test paper are wet (Schemer test‑I to measure basal tear secretion).
- To measure the reflex lacrimation (Schemer test‑II), another test paper is used with irritation of the nasal mucosa by an aromatic odour.
- Special signs in xerosis:-
1. Bitot spots which are triangular, white foamy patches on the bulbar conjunctiva. They occur due to abnormal activity of Meibomian glands and gas formation by proliferation of xerosis bacilli.
2. Rapid breaks in tear film as shown by "break up time test".
3. Conjunctival biopsy shows atrophy of goblet cells.
1. Corneal: - Keratitis, ulceration and keratinization.
2. Conjunctival: - Conjunctivitis, ulceration and keratinization.
1. Wetting of the eye:
a. Artificial tears as methyl cellulose 1 % eye drops.
b. Therapeutic contact lens of high water content + artificial tears.
c. Ointment at bed time.
2. In Xerosis we do scraping of Bitot spots and give systemic vitamin A.
3. Occlusion of the lacrimal puncti to decrease tear excretion in cases of severe sicca syndrome. Before permanent occlusion, we try temporary occlusion of the puncti for 1 week. If epiphora does not develop, we do permanent occlusion.