Q. Night Driving and Tinted Lenses
Are there any state or federally mandated laws that require a minimum light transmission for driving at night? We are a lens manufacturer and have customers who want to wear our yellow polarized lenses at night. We want to be sure there are no safety issues.--Eric Lindquist, Specialty Lens Corporation, Salt Lake City, Utah

A.
We checked with a number of sources on this question.

The American Optometric Association's attorney is not aware of any laws or statutes on the subject, but indicated that it is a subject of interest to the association.

The National Highway Safety Transportation Association reported: "This agency does not have authority over the actions of drivers. State, local, and municipal laws and statutes would apply. Wearing glasses that interfered with vision could fall under reckless driving laws, and tickets could be given."

We failed to get a response from the American Automobile Association, but the OLA's Technical Director Dan Torgersen reported as follows:

"There are no regulations I am aware of for minimum transmittance for night driving. There are some specifications given in ANSI and ISO standards. However, since these standards are voluntary, they are reference only. ANSI Z80.3 does list specifications for non-prescription lenses used for driving. These include traffic signal recognition, color limits, and 8 percent as the minimum luminous transmittance for daylight driving. However, there is nothing listed as a minimum transmittance for night driving.

"There are no transmittance requirements in Z80.1. In ISO 14889, Fundamental Requirements for Uncut Finished Lenses, the minimum transmittance for night driving is given as not less than 75 percent."

Q. Good Old Golden Rule Days
At what age should I begin recommending my kids get their first eye exam?

A.
Most children should begin having their vision checked annually before they enter school, unless there are outward signs of a problem. Parents need to keep in mind that 80 percent of the child's learning process comes through the eyes. If a child avoids reading due to poor vision, he or she may be improperly diagnosed with a learning disability or low self-esteem, among other possible problems.

Q. How Expensive is too Expensive?
I've heard of a progressive lens that is said to be custom made for each prescription in Germany. Can you explain the benefits of going to such great lengths and waiting so long for this "new" technology? Why are they so expensive? How does the manufacturer justify the cost?--C. Jennings, Pittsburgh

A.
The lens you've heard about is a new atoric progressive called Multigressiv II, produced by Rodenstock with individually calculated aspheric/atoric curves on the back surface, customized to the individual requirements of each prescription. The advantages of this technology are improved visual acuity, particularly in the periphery of the lens, and increase in the width of the visual zones in the intermediate and near portions. Wholesale laboratories are not equipped to produce these surfaces. Regarding the price, this technology costs some $70 more wholesale.--Alan Yuster, Rodenstock Lens EB

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