OCULAR CHANGES - COMPLICATIONS OF DIABETES.
1. Cataract.—The opacity, almost always bilateral, of the lens is a late symptom of diabetes and belongs almost without exception to the cases in which there is marked and obstinate glycosuria. The complication attacks by preference young persons, and when it occurs in the elderly is indistinguishable from senile cataract. If the corti cal substance of the lens is not destroyed, the cataract usually im proves purl passe with the improvement of the original disease. The causes of the opacity of the lens were formerly thought to be maras inns, abstraction of water from the lens by reason of the sugar con tained in the aqueous humor and in the vitreous body, the presence of sugar in the lens itself, or the change of the sugar held in solution in the aqueous humor into lactic acid. All of these explanations are untenable. Of late we have been taught that a toxic disease of the vessels in the ciliary processes is the cause of the disturbance of nu trition of the lens.
2. Retinal Diseases.—Those which are dependent upon diabetes occur under three forms : (a) Albuminuric retinitis accompanying contracted kidney present as a complication or sequel of diabetes; (b) Retinitis ceutralis punctata with characteristic ophthalmoscopic changes (small, shining central spots, usually with hemorrhagic puncta, always bilateral, without involvement of the optic nerves; Leber, Hirschberg) ; (a) Retinitis hfflmorrhagica of the ordinary type. The retinal diseases are incurable, and are of unfavorable prognostic import. Galezowski found 27 cases of retinitis in 144 cases of diabetes.
3. Optic _Nerve. —Neuritis, neuroretinitis, retrobulbar neuritis with consecutive atrophy of the optic nerve. These diseases are progres sive; they occur more frequently in the severe forms of diabetes than in the milder cases, sometimes as early, sometimes as late, compli cations.
4. Amblyopia and Anwtrosis, without Ophthalmoscopic Changes.
As long as these troubles are not of cerebral origin they belong to the early stages of diabetes. They are often the first thing that leads the patient, ignorant of the existence of dialJetes, to seek medical ad vice. The amblyopia appears in the narrowing of the visual field, hemianopsia, or central or paracentral scotoma in an almost normal visual field; in the latter case the affection resembles the so-called intoxication amblyopia, especially that due to the abuse of tobacco. It would appear, moreover, that many cases are actually to be referred to nicotine poisoning, which occurs more readily in the diabetic than in the healthy organism. These troubles, due for the most part to retrobulbar neuritis, do not readily yield to treatment.
5. Ocular iluscles.—According to Galezowski, paralysis of the ocular muscles occurs in seven per cent. of the cases of diabetes; the muscles of accommodation and the external rectus suffer with especial frequency and early. Mautlmer considers hemorrhage in the nuclear region, perhaps also at the base of the brain, as the immediate cause of the paralysis. Disease of the vessels is therefore, according to this theory, to be regarded as the connecting link between diabetes and these paralyses. Others, doubtless more correctly, look upon peripheral (toxic?) neuritis as the cause.
C. Other Ocular Troubles.—Iritis, iridocyclitis, spontaneous my opia (due to distention of the lens in the early stage of juvenile dia betic cataract or to softening and stretching of the sclera), opacities of the vitreous body (from hemorrhage), recurring scleritis, pustular and ulcerative processes of the cornea., ciliary border, or lids (clue to increased vulnerability of the parts), and ueuroparaly tic keratitis may be simply referred to as comparatively rare phenomena related di rectly or indirectly to the original disease.