Scrofula | 1,165| 71| 1,026 | 68| 6.1 | 88.1 | 5.8
b. Causes affecting iris | 1,307| 33| 1,093 | 181| 2.5 | 83.6 | 13.9
c. Causes affecting lens |11,769| 228| 9,467 | 2,074| 1.9 | 80.4 | 17.7
d. Other causes | 9,474| 235| 8,221 | 1,018| 2.5 | 86.8 | 10.7
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Nervous apparatus affected| 7,944| 276| 6,980 | 688| 3.5 | 87.8 | 8.7
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Unclassified |14,885| 938|12,463 | 1,484| 6.3 | 83.7 | 10.0
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(1) Congenital | 4,728| 632| 3,666 | 430|13.4 | 77.5 | 9.1
(2) Other causes |10,157| 306| 8,797 | 1,054| 3.0 | 86.6 | 10.4
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Unknown | 8,004| 313| 5,740 | 1,951| 3.9 | 71.7 | 24.4
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To quote from the Report:

The only specific causes, other than congenital, to which is
due a greater proportion of the total cases of blindness among
those whose parents were cousins than among those whose parents
were not related, are: Catarrh (parents cousins 28.1, parents
not cousins 8.7 per 1,000), scarlet fever (parents cousins
10.7, parents not cousins 10.1 per 1,000), scrofula (parents
cousins 28.9, parents not cousins 19 per 1,000), and measles
(parents cousins 28.9, parents not cousins 23.5 per 1,000). The
difference in these proportions is but slight, and the relative
number of cases of blindness attributed to each of the other
causes is greater among those whose parents were not
related.[77]

[Footnote 77: U.S. Census, 1900, op. cit., p. 17.]

It will be noted that the greatest proportion is in the case of
scrofula.

Since it is probable that a part of those who did answer the question
as to consanguinity are in fact the offspring of cousins, the
percentage in each case should be somewhat increased. Allowing for
these the same proportion as for those who did answer the question we
should have of all the blind 4.47 per cent as the offspring of
cousins; of the totally blind 4.14 per cent and of the partially blind
4.88. While of the congenitally blind we should have 14.7 per ce