EFFECTS OF RADIANT ENERGY ON THE EYE. G37 



The diagnosis and prognosis we can hardly better state than in the 

 words of Van Lint ^^^ in his report to the Belgian Ophthahnological 

 Society. 



" Diagnosis: The symptoms and evolution of the malady character- 

 ize very clearly accidents provoked by electric light. Nevertheless, 

 the diagnosis is sometimes delicate. Certain people, especially 

 employees w^orking habitually by electric light, complain of ocular 

 troubles which they assign to the influence of electricity. These 

 troubles have for the most part no relation to the cause invoked. 

 In the patient affected by conjunctivitis one generally finds a sliglit 

 infective conjunctivitis, if by troubles of vision one finds asthenopia 

 due either to a local cause, hypermetropia or astigmatism, or to a 

 general cause anemia, fatigue or the like. One must consequently 

 eliminate all these outside causes before concluding that the troubles 

 are chargeable to the electric light." 



"Prognosis: As one is able to see after a study of the symptoms 

 the prognosis is always favorable. A duration of about five days 

 seems to be necessary for the course of the malady. In case of nervous 

 asthenopia the prognosis is equally favorable provided one protects 

 the patient against the luminous sources. A case cited by Fere 

 endured six weeks, but the patient was affected by nervous symptoms 

 which had very remote relation with those provoked by electric light." 



Our first series of experiments was concerned with the relation 

 between cause and effect in photophthalmia of rabbits following 

 exposure to a powerful source of ultra violet radiation. As the source 

 of energ}' we employed a quartz mercury lamp operating on 220 \olt 

 circuit and normally taking 3.5 amperes with about 90 volts across 

 the terminals of the tube. This was the same lamp of which the radia- 

 tion has already been studied by one of us ^^ and which furnishes 

 by far the best source of energy for such experiments, inasmuch as its 

 ultra violet radiation is powei'ful and the light after running twenty to 

 thirty minutes to heat up is extraordinarily steady. It is also remark- 

 ably advantageous in the distribution of energy in its spectrum, since 

 it gives off relatively little radiation of long wave length, the nearer 

 infra red region being particularly weak, so that results obtained by 

 it are not complicated, save in some experiments with bacteria, by 

 any effects due purely to temperature. Although there is consider- 

 able heat loss in the lamp it is nearly all in the form of heat waves of 

 very long wave length which are wholly cut off by a cell containing 

 pure water, the infra red lines of the spectrum being ^•ery few. As 

 respects the radiation from this lamp, therefore, it is practically all 



