Discoloration of conjunctiva
Normal conjunctiva is a thin transparent structure.
In the bulbar region, underlying sclera and a fine network of episcleral and conjunctival vessels can be easily visualized.
In the palpebral region and fornices, it looks pinkish because of underlying fibrovascular tissue.
Causes of discolouration of conjunctiva.
Conjunctiva may show discoloration in various local and systemic diseases given below:
1. Red discoloration.
A bright red homogeneous discoloration suggests subconjunctival haemorrhage.
2. Yellow discoloration.
It may occur due to:
(i) bile pigments in jaundice,
(ii) blood pigments in malaria and yellow fever,
(iii) conjunctival fat in elderly and Negro patients.
3. Greyish discoloration.
It may occur due to application of Kajal (surma or soot) and mascara in females.
4. Brownish grey discoloration.
It is typically seen in argyrosis, following prolonged application of silver nitrate for treatment of chronic conjunctival inflammations. The discoloration is most marked in lower fornix.
5. Blue discoloration.
It is usually due to ink tattoo from pens or effects of manganese dust.
Blue discoloration may also be due to pseudopigmentation as occurs in patients with blue sclera and scleromalacia perforans.
6. Brown pigmentation.
Its common causes can be grouped as under:
(a) Non-melanocytic pigmentation
i. Endogenous pigmentation.
It is seen in patients with Addison's disease and ochronosis.
ii. Exogenous pigmentation.
It may follow longterm use of adrenaline for glaucoma.
Argyrosis may also present as dark brown pigmentation.
(b) Melanocytic pigmentation
i. Conjunctival epithelial melanosis.
It develops in early childhood, and then remains stationary. It is found in 90 percent of the blacks. The pigmented spot freely moves with the movement of conjunctiva. It has got no malignant potential and hence notreatment is required.
ii. Subepithelial melanosis.
It may occur as an isolated anomaly of conjunctiva or in association with the ipsilateral hyperpigmentation of the face.
iii. Pigmented tumours.
These can be benign naevi, precancerous melanosis or malignant melanoma.
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