The last named affection of the cornea, of which but a few cases had until then been- observed, was seen and described during the influenza period remarkably often by many. It appears from the third to the seventh day of influenza, and undoubtedly stands in causal relation to the latter. Some assume that it is due to an invasion by the influenza germs into the lymph spaces of the cornea. The process, which is said always to occur unilaterally, is very protracted and not seldom results in permanent corneal opacity. The disease consists of a central bleb, from which dendriform arborizations extend, consisting either of opaque corneal tissue or of sulci with opaque floor; together with this there are only slight irritation, anesthesia of the cornea in the region of the area of dimness, slight photophobia, and moderate pericorneal injection. This influenza keratitis is also deserving of notice in that it resembles somewhat another infectious disease of the cornea, the malarial keratitis of Kipp, with which it seems to be clinically identical.
* Compare Ruhemann, loc. ext., p. 147.
Of the other diseases of the cornea, there were also observed postinfluenzal parenchymatous and hypopyon keratitis.
Of the diseases of the eye observed during and after influenza, we have yet to add: hyperemia of the iris, plastic iritis, iridochoroiditis and cyclitis, suppurative choroiditis terminating in purulent panophthalmitis, and phthisis bulbi; also fresh vitreous opacities and hemorrhages into the vitreous. Acute and occasionally even hemorrhagic glaucoma was repeatedly observed. Retinal hemorrhages and detachments of the retina and embolus of the central retinal artery have been described; also thrombosis of the retinal arteries, analogous to the previously mentioned arterial thromboses of the extremities (Dujardin). Pfluger, Bergmeister, Scholer, Snell, and Hardy report papillitis, neuroretinitis, and optic neuritis; Pfluger, Gutmann, Ruhemann, Bergmeister, and Eperon mention retrobulbar neuritis. Retrobulbar hematomata with exophthalmos are also mentioned.
Of the affections of the orbit, there occur: Inflammation of the capsule of Tenon, suppurative tenonitis terminating either in recovery or purulent panophthalmitis.
Of the affections of the sensory ocular nerves, we may mention photophobia, retinal hyperesthesia, and especially the frequent pain in the eyeball extending deep into the orbital cavity (neuralgia of the intra orbital branches of the trigeminus).
The many paralyses of the internal and external ocular muscles have been extensively considered in the section on Influenzal Neuroses. (Compare pp. 641 and 642.)
We are still quite in the dark concerning the pathogenesis of the numerous ocular affections just mentioned (whether due to influence of the toxin or invasion by the specific bacilli). The majority of the inflammatory processes, with the exception of the regular conjunctivitis, are probably, especially in the severe purulent conditions, due to a mixed infection with the ordinary pyogenic cocci. The presence of Pfeiffer's influenza bacillus has not yet been demonstrated in ophthalmic practice.
Undoubtedly, numerous diseases of the eye which occurred after recovery from influenza have, in the absence of other etiologic factors, through the vague etiology of many ocular diseases, been erroneously attributed to influenza, with which they had either but slight or no causal relation. [Anemia also occasionally follows influenza,-Ed.]