BOWMAN LECTURE. CV 



affected members, but nothing like universal, and V. 

 corrected is also apt to be subnormal. The relations of 

 this group will have to be worked out by future 

 observers. 



LEBER'S DISEASE. 



(Figs. 45 to 52 in text, 48 being inserted at p. Ixii.) 



The hereditary optic neuritis, or, as it is often called, 

 optic atrophy, described by Leber, is so well known that 

 I need dwell only upon certain points that call for further 

 study. 



Although nearly always symmetrical and usually 

 simultaneous in onset, it is sometimes unequal in 

 intensity in the two eyes even to the degree of 

 occasionally leaving one eye untouched, as in a case by 

 Johnson Taylor,* or but slightly affected, as in Norris's 

 case (Fig. 49, IV. 13), whilst an interval of weeks between 

 one eye and the other is not very rare, and even years 

 occasionally intervene (see Fig. 51). After an acute 

 or subacute onset the climax is generally reached in a 

 few weeks or months and no further change takes place, 

 the leading permanent feature being a central or nearly 

 central scotoma that varies in size and density in different 

 cases. Peripheral loss of field is much less common. 

 Total blindness is said to ensue in rare instances, but I 

 believe this has generally rested on lay testimony. The 

 usual age of onset is about 20 years. The subjects 

 are males in a large majority of cases, but descent nearly 

 always takes place through the unaffected mother. Con- 

 sanguinity of parents is but seldom met with. In only a 

 few cases do we find a history of other neuroses (most 

 often epilepsy) in the patient or his relations. The 

 following are good illustrative pedigrees of Leber's dis- 

 ease :t 



* T.O.8., xii, p. 146, Case 3. June 12th, 1909: Mr. Johnson Taylor 

 has kindly re-examined the members of this genealogy quite recently 

 and brought the history down to date. See Fig. 110, Appendix VI, a. 

 f For the other data on Leber's disease see Appendices I, i, and VI. 



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