Friday, July 4, 2008

Bifocals for kids

Executive-style lenses for children are overkill. For one thing, these lenses are often prescribed to reduce accommodative esotropia, which often occurs in highly hyperopic children (who need a high plus power). These lenses are excessively thick, heavy, and limited in material availability.

A FT-35 should provide more than enough width for a child (I can't imagine a child turning his/her gaze out that far to read anything -- it's almost a 40-degree eye rotation). Also, a FT will leave a little temporal vision for seeing the ground in the periphery more easily. It should be pretty easy to get a FT-35 in several materials, including polycarbonate.

As far as progressives for children... I would be tempted to use a short-corridor progressive, myself (and only if cosmetics are a serious issue). Most children wearing bifocals do so because of binocular vision disorders, not because of reduced accommodative amplitudes. This means that children can often see clearly anywhere through the distance, corridor, or near zone of the lens. However, if the child doesn't reach the full power of the near zone the benefits of the lens are not realized. This is exactly why bifocals are positioned so high with children. Progressive lenses, which already require more depression of the eyes while reading, must be positioned several millimeters above the pupil on children. You should also be aware of reduced distance and near utility.

On the other hand, certain "computer" lenses might show more promise for children. I believe there was actually a study conducted to evaluate such lenses for children, although I do not have the results handy. Blended bifocals, fit high, might also be an affordable option.

By Darryl Meister

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