Soft, extended-wear contact lenses, one reason the number of contact lens wearers has risen sharply in recent years, may soon be obsolete.

A new kind of lens, the extended-wear hard lens, may win Food and Drug Administration within a year, a leading optometrist told a symposium on contact lenses in Boston last month.

"The soft lenses are best at day one and then get worse because the material deteriorates," says Dr. Harold E. Davis of Chicago. "The hard lenses are worst at day one and get better as the wearer adapts to them."

First-generation soft lenses became available in 1971 and quickly began to replace their hard predecessors.

Ten years later, extended-wear lenses, which are more comfortable and can be worn for extended periods because they allow oxygen to pass through, became available. Since 1977, the percentage of Americans contact-lens wears has doubled. But they have limitations. The soft lenses cannot be used to correct some vision problems, and they often must be replaced every year.

Davis, former president of the American Optometric Association's contact lens section, says extended-wear hard lenses are "the light at the end of the tunnel," providing the sharp vision of hard lenses and the comfort of soft.