Astigmatism. Astigmatism is the eye fault of unequal curvature in the eyeball, particularly of the cornea. It is very common and causes most eye strain and vision distortion. Theoretically,
Fig. 10. Astigmatism, unequal curvature of the eyeball, distorts entering light rays, possibly to very slight degree. This out-of-round situation of the front of the eye distorts vision and creates eye strain. Effectively treated with glasses, it is a most common if not universal eye difficulty.
because nothing in this world is perfect, no eyeball is perfectly round and therefore, everyone has some astigmatism. It is usually relieved with suitable glasses.
Exophthalmos. This uncommon eye condition makes the eyeball appear enlarged, staring, and frightened; often as the result of disease. This appearance is caused by the eyeball being pushed outward, sometimes by a swollen or congested area behind the eye. It is frequently seen in over-activity of the thyroid, but can also occur from high blood pressure, kidney disease or
Fig. 11. Wide, staring eyeballs, called exopthalmus, sometimes are caused by thyroid disease. Enlarged thyroid (goiter), along with wide, staring eyes, shows the origin of the medical term, “exopthal-mic goiter.”
as an inherited family characteristic. It is seen mostly in men, and develops toward middle age. Even after effective treatment, it is usual for the exophthalmos to remain as a permanent feature.