There are many causes for this condition such as optic neuritis, meningitis, acute infectious diseases, locomotor ataxia, arteriosclerosis, nasal disease, syphilis, traumatism, alcoholism, exposure, embolism of the central retinal artery, diabetes and poisoning. Diagnosis must determine the original cause. =Treatment.=—I have mentioned conditions in the nose as frequently accounting for various eye troubles. If these atrophies of the optic nerve can be gotten early, many of them will be influenced very favorably by osteopathic treatment. Spinal treatment to direct the circulation to the area of the orbit at the base of the brain is beneficial. Regulation of the patient’s diet, habits, methods of living and so forth is important. Excessive mental strain, excessive sexual intercourse and stresses of every kind should be prohibited. Special treatment should then be given according to the causal factors entering into the case. Eye Strain and Its Reflexes For the subject of refraction and refractive errors such as the different forms of hypermetropia, myopia and astigmatism the reader is referred to the many excellent works on ophthalmology which cover these subjects quite thoroughly. They are only used here in the relation to eye strain and its reflexes. The osteopathic logic here given should be combined with a reading of the refractive errors in such works as Fuchs, Weeks, De Schweinitz and others. Asthenopia =Eye strain, weak sight or asthenopia= embraces the group of symptoms dependent upon fatigue of the ciliary muscles or of the extraocular muscles. There are three varieties of asthenopia. (1) Retinal or nervous, (2) muscular and (3) accommodative. The symptoms are headache—frontal, fronto-temporal or fronto-occipital. It may extend into the neck between the shoulders. Eye balls may be tender, diplopia at times, may be photophobia, lachrymation, congestion of the eye, itching and burning of the lids. =Accommodative Asthenopia.=—In this form the ciliary muscle is fatigued. The cause is usually overuse of the eye when hyperopia and astigmatism exist; sometimes in myopia or presbyopia. =Treatment.=—In this form the treatment is the proper fitting of glasses and improvement of the general health. =Muscular Asthenopia= is due to tiring of the extraocular muscles, usually the internal rectus. This may result in a phoria or a non-paralytic squint. Ametropia may exist but asthenopia may come even in emmetropia due to overuse of the eye. =Treatment.=—Correct ametropia if present, with glasses. Exercise the weakened muscle. Correct the nerve supply to the weak muscle. Treat cervical and upper dorsal. Manipulate tissues of the orbit. Spring the jaw. Correct any nose and throat pathology. =Nervous, Neurasthenic or Reflex Asthenopia.=—The cause is supposed to be some functional disorder, more often found in females. May be due to too dim or too bright light, overuse of the eyes. Hysteria may follow ametropia.