Follicle: localised area of lymphoid herplasia, appearing white or grey elevations in the upper or lower tarsal conjunctiva, which may be accompned by inflammation(folliculosis) accompanrd by viral, allergic or bacterial conjuctivitis.
Follicle formation in conjunctiva is a lymphoid
reaction to insult of the conjunctiva, eg, bacterial, viral, irritant and drugs.
Follicles are small hemispherical
raised spots; there is no vessel in the
follicle. It mostly comprises lymphoid tissue,
with vessels either surround the follicles or
develop underneath them.
Causes of follicles are trachoma, chronic follicular
conjunctivitis and drug reaction. They are
generally seen in the lower fornix. In trachoma
they are seen in the palpebral conjunctiva also
Conjunctival follicles only occur after 3 months of age, as lymphoid tissues in conjunctiva are not developed before 3 months of age.
It is important to differentiate papaillae from folllicles.