Iritis occurring in these last suggests the possibility of error in the diagnosis of the putative parent disease. Especially is the clinical similarity of gonorrhœal (polyarticular) rheumatism to rheumatoid arthritis to be borne in mind.
The Relative Incidence of Iritis.—In the text-books it is often stated that the syphilitic form of iritis is the one most frequently met with, and that gouty iritis, if it is met with at all, is much more rare. But in these comparative statements we have no clue to the frequency of iritis with syphilis, nor of iritis with gout. For a true analogy we do not want the syphilographer to tell us the aggregate number of cases of iritis that he has seen, but what is the percentage of cases of syphilis in which iritis occurs, and we want the gout physician to state his percentage of iritides in gout, or, negatively, what is the percentage of cases in which iritis does not occur.
If gout is a more prevalent disease than syphilis, it does not follow that “gouty” cases of iritis will be more numerous than those due to syphilis. Let us suppose, for the sake of clearness, that 1 per cent. of people suffering from gout get iritis, and that also 1 per cent. of people infected by syphilis get iritis, and that in a certain town there are two hundred people who are gouty and one hundred people who are syphilitic. It is probable that there will be two persons suffering from gouty iritis (always supposing there is such a disease), but only one from syphilitic iritis. The absolute totals will differ, but the relative will be identical. It is clear, then, that infectivity cannot be gauged by the statistical enumeration of the consulting-room. Gout is a rarer disease than our patients would have us believe, but accepting their views, even then we should expect to see more cases of iritis caused by it, if such existed; we should expect to find more definite proof of a causal connection, and less frequently a history of gonorrhœa, of pyorrhœa, and of syphilis.
No Uratosis, no Gout.—If we pin our faith to the equation
Hyperuricæmia + Uratosis = Gout,
we can at once exclude all cases of ocular disease as gouty in the absence of either factor. According to Garrod, “true gouty inflammation is always accompanied with a deposit of urate of soda in the inflamed part.” We should therefore expect that uratosis would occur in situ if an iritis were gouty. But it does not: the touch-mark is absent, and there are no chemical, pathological or clinical signs of urates in the iris after the inflammation has subsided. What then is the alternative? Either Garrod’s aphorism is inaccurate or iritis is never gouty. In other words, we must postulate that an iritis may be regarded as gouty without uratic deposits. If this be the case, the so-called gouty iritis may well rank with the occult migraines, flatulencies and acidities which are termed irregular, suppressed or latent gout. Strictly then it would be a latent gouty iritis fit to rank with that last refuge of the uric acid enthusiasts, the “latent nephritis” which they worship as the fons et origo mali of gout.
Metastasis.—The predilection of the gonococcus for synovial membranes is seen not only secondarily to urethral infections, but also in ophthalmia neonatorum, in which the joints of infants are affected sequentially to the eyes.[51]
The gonococcus also has been found in cases of peritonitis, pleurisy, pericarditis, etc., but it is said to have only once been isolated in the eye in iritis.[52]
It is not only the gonococcus which can initiate a metastasis from the eye to the joints, to the peritoneum, or elsewhere. The same process may be started by the bacillus typhosus, by the streptococcus of erysipelas, and by that of puerperal septicæmia.