lec 4 endocrine thyroid disease

endocrine
lec: 4 dr.mohammed alhamdany
graves’ ophthalmopathy
this condition is immunologically mediated but the autoantigen has not been identified.
pathophysiology:
there is cytokine-mediated proliferation of fibroblasts which secrete hydropinghilic glycosaminoglycans. the resulting increase in interstitial fluid content, combined with a chronic inflammatory cell infiltrate, causes marked swelling and ultimately fibrosis of the extraocular muscles and a rise in retrobulbar pressure. the eye is displaced forwards (proptosis, exophthalmos) and in severe cases there is optic nerve compression.
clinical feature:
it is helpful to distinguish patients with active inflammation from those in whom the inflammation has ‘burnt out’. the sign of active inflammation include:
1- periorbital oedema.
2- conjunctival inflammation.
3- changing orbital signs.
eye disease is detectable in up to 50% of thyrotoxic patients at presentation, but active ocular inflammation may occur before or after thyrotoxic episodes. it is more common in cigarette smokers and is exacerbated by poor control of thyroid function, especially hypothyroidism.
the symptoms include:
1- there may be excessive lacrimation made worse by wind and bright light.
2- a ‘gritty’ sensation in the eye.
3- pain due to conjunctivitis or corneal ulceration.
4- there may be reduction of visual acuity and/or visual fields as a consequence of corneal edema or optic nerve compression. other signs of optic nerve compression include reduced colour vision and a relative afferent pupillary defect, if the extraocular muscles are involved diplopia results.
treatment:
1- the majority of patients require no treatment.
2- smoking cessation.
3- methylcellulose eye dropings and gel reduce gritty discomfort of dry eyes.
4- tinted glasses reduce the excessive lacrimation triggered by sun or wind.
5- in patients with mild graves’ ophthalmopathy, oral selenium (100 ?g twice daily for 6 months) improves quality of life, reduces ocular involvement and slows progression of disease the benefits persisted 6 months following cessation of therapy.