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One would postulate that there should be a larger proportion of hypermetropic children
amongst infants, and that therefore they would yield the highest percentage of " No Change "
cases. The Tables show that this is so, the percentage figure being twice that of other age
groups. Conversely, at the other end of the scale the infants provide the lowest percentage of
children decreased by 5 Snellen lines. Theoretically one would expect that infants would provide
a smaller percentage of all cases of decrease in vision with a + 1 sphere than would other
age groups, and this is so in decreases of 1, 2, 4, 5 and 6 Snellen lines—but in a decrease of
3 Snellen lines the infants have a much larger figure than other age groups. I do not know
if there is any significance in this.
In Table I. (Total Children) it will be seen that a decrease of 3 Snellen lines represents
over one-third of all children tested, and this figure is repeated when analysed according to
sex. It seems probable that this decrease of 3 lines represents the most normal reaction to
reading with a + 1 sphere, and infants, therefore, show a higher percentage of normality
than do other age groups.
Indeed a decrease of 2 and 3 Snellen lines accounts for 57% of all the children, and it
seems reasonable to take these degrees of diminution of vision as normal.
Theorising from figures, however, particularly a small number such as 3,064, is usually
unprofitable and often dangerous.
Summary.
1. The advisability of a more thorough scheme of visual examination of school children.
This is stressed by the Committee of Inquiry of the Board of Education, who, as a result
of their investigations point out the danger of early myopic conditions being overlooked.
This must be the practical experience of all those who do refractions in the School
Clinics. From time to time children appear at the Refraction Clinic with a visual acuity of
6/24 or less—children who have never left the district, and who have been examined and found
normal at their previous routine examinations. Refractions show from 1-2 diopters of myopia.
How are such children to be found and treated earlier ?
2. The use of the + 1 sphere in the routine vision testing in the schools appears to
offer a useful method of detecting children who require further investigation—but its value is
at present minimised by lack of knowledge as to what is the real meaning of the results
obtained. The number of children whose vision is adversely affected by a + 1 sphere was
90% of those children who would be passed as normal under the ordinary procedure. This
makes refraction impossible unless it were made the subject of a special inquiry.
3. Under 1% had their vision reduced by 5 Snellen lines or more, and therefore represent
the greatest deviation from the normal reaction of visual acuity when a + 1 sphere is used,
and should be in the greatest need of further investigation. The smallness of the figure
makes this a practicable proposition, and it would seem desirable to refract and follow up all
such children.
4. The refraction results of the twenty cases show slight hypermetropia and slight
myopia combined in many cases with an astigmatism of 0.25 diopter.
The question then arises : Should slight myopic errors be corrected by the prescription
of lenses in cases of good vision and with no subjective symptoms?
On the assumption that the myopia will progress and that the wearing of correcting
lenses will prevent or check this advance, the answer should be in the affirmative—but wc
have no precise knowledge of this, only the known general tendency of myopia to increase in
the growing child.
The individual factor, also, cannot be overlooked, and it may well be that small
degrees of myopia fit in satisfactorily with the general "make-up" of some children, and are
in fact normal for such children. I am strongly of opinion that small errors of any kind
should not be corrected unless there is evidence of a lessened visual acuity or signs of strain.
But such children should be followed up and their vision tested frequently in case symptoms
should arise at a later date.
5. Greater frequency in testing the vision of school children would seem more advantageous
than increasing the numbers of refractions by endeavouring to refract children who
may be slightly myopic though without symptoms. So long as children are discovered and
treated within a short time of the appearance of symptoms, there cannot be any real injury
effected.
At present, however, the long intervals between the routine inspections make it possible
for children to be left for years with a disability untreated. This is particularly so during the
four year interval between Intermediates and Leavers—and at the very period when visual
defects are likely to manifest themselves owing to the increased work at school.
True, there are the School Clinics to which a child can always be referred if the defect
is noted, and many do obtain treatment in this way. But many also are missed by parent or
teacher—this year 250 cases of visual defect were discovered at the routine inspection against
112 found during special inspection at the School Clinics.
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