How Long Must the Near Work Be

How Long Must the Near Work Be

Performed to Induce Myopia?

 

Initially, the amount of near work was quantified

in “diopter hours”(amount of accommodation

 duration in hours).However, there was an

inherently low correlation between myopia

progression and the amount of near work, as

measured in diopter hours [43], although significant

correlations were achieved because of

the large numbers of samples already in the

early studies (i.e., 793 children.

  A large

study on the relationship of near work and

myopia in 1,005 school children in Singapore,

7–9 years old [54], showed that axial eye length

was correlated to the myopia of the parents

but also to the numbers of books that were

read per week. There was a significant increase

in myopia when two books were read vs when

one book was read, but only in those children

whose two parents were myopic. One possible

explanation for the relatively low correlation

between near work and myopia is that

the exact behavioral pattern during reading

may be important. It was already suggested by

Winawer and Wallman [87] that diopter hour

may not the best unit to predict myopia from

near work.

 

Summary for the Clinician

         If the observations in animal models (see

are applicable to human myopia,

interruption of reading for only short periods,

and looking at a distance, should effectively

inhibit the growth signal for the eye.

More research is necessary in the monkey

model and in children to find out whether

temporary wearing of positive lenses could

further strengthen this inhibitory signal for

axial eye growth

 

Night Light, Blue Light

            Based on the observation that the ocular growth

rhythms are disturbed during development of

deprivation myopia in chickens [82, 44],whether

diurnal light rhythms might interfere with

myopia development in children was tested. In

the initial study [52], a high correlation between

exposure to light during the night and myopia

development was found. Later studies [15, 89]

could not confirm this relationship and one

possible explanation was that myopic parents

had the lights on at night more frequently. The

higher incidence of myopia in their children

 

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