Combinations are describable in similar terms. A tendency of the right eye to turn up and inward, is a “right hyperesophoria”; the left eye to turn down and out, a “left hyperexophoria,” etc. Tendencies of both eyes together are denoted by the terms which follow:
- Anaphoria signifies an upward tendency.
- Kataphoria signifies a downward tendency.
- Dextrophoria signifies a right tendency.
- Laevophoria signifies a left tendency.
Chapter XVII
SYMPTOMS OF HETEROPHORIA
These depend on the kind of error present as well as the degree and widely vary.
In general, they may be said to fall into three classes—(1) defective vision, (2) pain of greater or less degree—(3) reflex symptoms.
Defective Vision. The first class may be present, even though each eye has a normal visual acuity; since, even when compensation is very good, the brain gets the impression of two objects, nearly, though not quite fused; and vision may be considerably worse with both eyes together than with either eye singly.
When compensation is considerably impaired, the diplopia becomes more and more persistent, till the brain finally makes choice of one image as more satisfactory, entirely suppressing the other. Visual acuity may not suffer in either eye; but vision being no longer binocular, everything is seen in the flat, the judgments of depth and distance being regularly more or less defective. While this is a tremendous disadvantage in many occupations, people gradually and not infrequently become accustomed to these visual defects and are not conscious of the handicap.
Pain. It is quite different with the second set of symptoms, which are always accompanied with pain. In fact, the character of the subjective symptoms in refractive errors and muscular imbalance is so similar that it is practically impossible to differentiate in many cases.
In muscular asthenopia, however, in addition to becoming easily tired, the patient often complains that letters seem to jump or run together or he may contend that he sees double for an instant; or again that he can “feel his eyes turn” involuntarily in their sockets. These pains or conditions are sometimes present only during actual use of the eyes. At other times they persist for hours. In some cases, after days or weeks of overstimulation, an explosion in migraine form occurs at irregular intervals. This condition often lasts a day or two.
Reflex Symptoms. In the third and last case, there are other reflex symptoms—such as dizziness, nausea, fainting, indigestion, insomnia and pains in other portions of the body—sometimes stimulating organic diseases.