SECONDARY CATARACT.—ThiS CORdi tion refers to the changes that are, at times, observed in the capsule of the lens following, for example, extraction of cataract. It is frequently seen after the attempted removal of an immature cat aract in which a portion of the lens substance remains. This occurs when the capsular membranes become agglu tinated together and the escape of any remaining lens-material is prevented. In many instances it happens that the entire pupillary area is not covered by the opacity, and fairly-satisfactory vision may be obtained.
When the condition does not develop until some months after the primary op eration for extraction, it is generally de pendent upon a fresh proliferation of the epithelial layer, with reduplication of the capsule.
Etiology.—Congenital conditions op erating upon the causation of cataract, which, at times based upon well-founded clinical observation, have been deter mined to be hereditary in type, prac tically resolve themselves either into developmental disturbances in the eye or antenatal inflammatory reaction of the organ.
The influence of heredity in the pro duction of cataract traced through six generations. In no instance was there any evidence of consanguinity. The transmission was effected by females alone. Promaget (Gaz. Hebd. des Sci ences Med. de Bordeaux, July 30, '93).
Senile change does not produce cata ract, but predisposes to it; the efficient determining causes are both ocular and general, while the general eauses are not particular diseases, but the condi tions arising in the course of disease. Jaekson (Universal Med. Journal, Dec., '93).
General disease, independent of senil ity, particularly if of vascular or lym phatic type, becomes, at times, a causa tive factor. Thus, diabetes mellitus is responsible for about 1 per cent. of cases, this variety being bilateral and develop ing rapidly. Rachitis, nephritis, and some affections of the skin are credited with the production of the condition.
Cataract affecting primarily the pos terior pole and cortex is not uncommon in association with retinitis pigmentosa and other diseases of the pigmentary coat of the eye; but, apart from these conditions, the presence of this variety of opacity of the lens is strongly indic ative of the presence of some serious interference with proper tissue metab olism, and, of all such alterations, by far most frequently of diabetes. The
special form which the variety takes is that of a rounded central posterior polar opacity. along with the formation of strim in the posterior layers of the cortex, these strifn being broad at the equator of the lens, with their apices pointed to the posterior polar region. These stri become broader and broader at the expense of the intervening clear portions, and then the opacity spreads to the anterior cortical layers, and last the eentral portions hecome non-trans parent. The author thinks that there is quite a sharp line of distinction into two classes of cataract ill regard to this matter. In one, the anterior cortex is affected before the posterior; this is the ordinary senile cataract. In the other the posterior cortex and pole are af fected first, as described above; this is the form associated with choroidal dis ease and metabolic anomalies. Klein (Wiener klin.Wochen.,45, 1901; Ophthal mic Review, April, 1902).
Certain tonics, such as ergot and naph thalin introduced into the system, are eminently causal in character.
Local diseases and traumatism fre quently produce all forms and varieties, influence directly upon the unprotected and exposed fibres themselves.
Influence of astigmatism in the genesis of cataract: in 33 cases of bilateral cata ract, 20 were found in which the more astigmatic eye first became cataractous, 5 were seen in which tbe less astigmatic eye was first affected, and 8 in which astigmatism was either absent or equal in the two eyes. Astigmatism should not be considered a cause of cataract, but rather as simply a condition which favors its development. Rome (Recueil d'Opbtal., Jan., '95).