THE CONSUMER movement has developed two conflicting drives - one in support of government regulation and one opposed to it. Nothing illustrates the situation as well as the recent actions of the Federal Trade Commission. Last week, it voted to end most restrictions on advertising the prices of eye glasses, contact lenses and eye examinations. A few weeks earlier, it had voted to study the advisability of placing new restrictions on advertising aimed at young children. The two actions are not completely contradictory. But taken together they suggest both the difficulty of regulating "in the consumer interest" and the way the perception of that interest changes.

The restrictions that now exist on price advertising of eye-care services and products were created by the states in the first two-thirds of this century. They were put in place , either through legislation or state-sanctioned codes of ethics, because the public was being badly served by the eye-care industry. Or so it was said at the time. Cut-rate eye care, the public was told, meant poor eye care. Restrictions on price advertising were necessary, as the Supreme Court put it just 15 years ago, "to assure high standards of professional competence."

The FTC's ruling last week rejects that entire rationale. Price advertising, the commission found, will reduce the cost of eye care without diminishing its quality. Quality can be controlled in other ways, it is now argued, and the bars against advertising have always been supported primarily by those in the eye-care business who don't want consumers to price-shop.

The FTC is probably right in its conclusion, but whether its new rule will stand up in court is another matter. It is exercising broad rule-making power over an entire industry for the first time and, if its action is upheld, similar rules to remove bars against advertising in other fields will surely follow. But it should be noted that, in the interest of the consumer, the federal government is trying to eliminate regulations that were imposed by the states to protect that same interest.

The problem, obviously, lies in defining the consumer - or public - interest. One change from 50 years ago, when those advertising restrictions were popular, is that the educational level of the public has risen. The restrictions were imposed to protect an unsophisticated public from charlatans and frauds; one premise of removing them has to be that the public is now clever enough to protect itself. That may well be true, especially since 112,000,000 Americand wear glasses and spend about $4 billion a yearfor eye care. But if it is true, what about the other kinds of regulation aimed at protecting the public from it s own unwitting mistakes?

That, of course, gets us back to the FTC and sugarcoated cereals. You could argue that the FTC is willing to trust parents to buy good eyeglasses for their children but not good cereals. Or that it thinks parents can withstand pressure created by advertising to buy flashy, bad glasses but not flashy, bad toys. What is the real consumer interest, in these and other areas, to which government regulation - or deregulation - should be directed? Price, as in eye glasses? Nutrition , as in cereal? Quality, as in drugs? Safety, as in automobile air bags? What about stepladders and slick barn floors?

The answer isn't always as easy as the advocates of regulation make it sound. The rule of thumb we prefer is one to which the FTC seems to be tending in the eye-care case: Don't regulate in those areas in which the public can reasonably be expected to have enough knowledge to buy intelligently. If the government would follow that general rule, President Carter's goal of large-scale deregulation might become a reality.