Ocular manifestations of thyroid disease

Ocular manifestations of thyroid disease

Hyperthyroidism (Thyrotoxicosis)

Thyrotoxicosis is the clinical syndrome caused by excess secretion of thyroid hormones. Thyrotoxicosis is a feature of two quite distinct disease entities: toxic nodular goitre and Graves' disease.

Toxic nodular goitre

In this condition, thyroid hormones are secreted by a thyroid adenoma independently of the normal pituitary controlling mechanism . Multinodular disease occurs in females over 60 years old, and the less common singular nodule is seen in younger patients. Unless the tumour is sufficiently large to cause symptoms by local compression the clinical features of the disease are the consequence solely of this excess secretion. The only ocular abnormality to be found is over activity of the sympathetically innervated fibres of the levator palpebrae superioris muscle. Normally the upper eyelid covers some of the iris, but in this condition a rim of white sclera is exposed above the upper margin of the iris, causing a staring appearance with widening of the palpebral fissure and lid retraction when the patient looks ahead. If lid retraction is not observed, lid lag may be

demonstrated by asking the patient to follow the examiner's finger held at

arms length from him through an arc from 45° above to 45° below the horizontal.

Graves' disease

Graves' disease is an autoimmune, systemic disease affecting many tissues

which may include the thyroid gland and the eye. Unlike the toxic nodular

goitre whose clinical manifestations are only those of excess thyroid hormone secretion, in Graves' disease thyrotoxicosis is usually, but not always, present and is only part of the disorder, and the ocular changes, except for lid retraction are due to other still unknown causes. Graves' disease is due to the presence of IgG antibodies to the TSH receptor of the thyroid follicular cell. The features of Graves' disease are: Hyperthyroidism, when present, is due to excess thyroid hormone secretions, the production of which is stimulated by ill understood factors whose effect is superimposed on the normal pituitary and hypothalamic controlling mechanisms. It is the nature of the control which has changed and the patient may be either hyperthyroid or euthyroid

Pre-tibial myxoedema is characterised by bluish brown plaques of

mucopolysaccharide infiltration which are found on the feet and lower legs. It can occur in association with finger clubbing, phalangeal periosteal new bone formation and overlying oedema, a triad known as thyroid acropachy.

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