- -Endocrine Disease.t --- - - - - - - -- - - - - - - - - 4. O ptic N erves Bilateral retrobulbar neuritis may also be present. If the hypothyroidism is not treated, optic atrophy may result. 5. Field Defects Bitemporal hemianopsia and visual failure sometimes occurs and is due to hypertrophy of the pituitary gland in response to the hypothyroidism, with consequent pressure effects on the optic chiasma. In other instances the hypothyroidism is secondary to a primary pituitary tumor. The ocular changes of hypothyroidism are reversed by thyroid hormone administration.
P ARATIIYROID GLANDS: Hyperparathyroidism ( Von R ecklinghauseo's D isease of Bone) This is a rare condition due to excess parathyroid hormone, caused usually by an adenoma. The serum calcium concentration is raised and consequent ocular changes consist of deposits of calcium containing crystals in the bulbbar conjunctiva. Hypoparathyroidism A decrease or loss of parathyroid function is followed by a subnormal serum concentration of ionized calcium with all its consequences including hyperirritability of the nervous system and tetany. Ocular signs consist of blepharospasm, twitching of the eyelids, and lacrimation. If the hypocalcemia is of long duration small discrete punctate opacities may occur in the Ieos. They are usually bilateral and rarely interfere with vision. Occasionally, however, such cataracts develop very quickly and may require operative removal. A common cause of hypoparathyroidism is accidental surgical removal of the parathyroid glands. 36
PITUITARY GLAND: The ocular aspects of pttwtary dysfunction manifest itself mainly through the direct mechanical effect of tumor formation on the optic chiasma; characteristic bitemporal field defects occur, and the oculomotor nerves may become involved through lateral expansion of the tumor, resulting in abnormalities of eye movements. The pituitary tumors may also affect other endocrine glands and these, in turn, may give rise to ocular manifestations.
Basophil T umor These are usually to small to cause local pressure effects on the optic chiasma, but, because of their effect on the adrenal glands, they give rise to a secondary hypertension which may cause a diabetic retinopathy similar to that produced by essential hypertension. It may also give rise to thyrotrophic exophthalmos and exophthalmic ophthalmoplegia, as well as thyrotoxicosis.
Acidophil T umor Apart from its mechanical pressure effects on the optic chiasma this tumor frequently gives rise to giantism or acromegaly. A direct ocular effect of this condition is the increased prominence of the supraorbital ridges.
Chromophobe Tumor These are by far the most common tumors of the anterior pituitary gland. Their main symptoms and signs are due to their direct pressure effect on the optic chiasma. An important complication is the progressive involvement of the optic nerve which may lead to blindness. Some of these tumors cause pituitary insufficiency. The resulting hypothyroidism may cause its characteristic ocular manifestations to be present. U.W.O.
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