When VAMPAC, the Virginia Medical Political Action Committee, asked gubernatorial candidates J. Marshall Coleman and Charles S. Robb whether optometrists should be allowed to administer eye drops and other medication to customers, it turned out to be a $16,000 question.

Republican Coleman told a candidate-screening committee from the doctors' PAC at a private meeting last summer that he opposed the idea and supported Gov. John N. Dalton's previous veto of an "eye-drop bill." Democrat Robb was noncommittal.

Within a few weeks, VAMPAC's ophthalmologists, who bitterly fought the legislation as an incursion on their medical practices and fees, had forwarded a check for $10,000 to the Coleman campaign. Optometrists who favor the legislation donated $6,000 to Robb through their own PAC.

While Robb and Coleman publicly stump for the Virginia governorship on a variety of fiscal and social issues, they are waging another, less visible campaign for votes, and money, from Virginia's influential interest groups. Because state election law has no limits on the amounts individuals can contribute and no ban on corporate donations, the special interest campaign has been freewheeling. Many groups have given equally to both sides, fueling campaigns expected to total more than $4 million -- the most expensive gubernatorial contest in Virginia history.

"The bulk of the money in Virginia is smart money," says Roanoke Sen. Ray L. Garland, a Coleman supporter. "It has no permanent alliances, only permanent interests. It is totally cynical money."

While the link between donations and campaign commitments is often not as direct as in the case of VAMPAC, both Coleman and Robb have made commitments to interest groups on controversial issues that seldom show up in campaign press releases. They have been rewarded with financial support in return:

Both candidates and their running mates for lieutenant governor have told bankers and retailers that they will not oppose increasing the state's interest ceiling on credit card loans. The bankers and retailers tried unsuccessfully during the last General Assembly session to eliminate the interest limit, which is set at 18 percent per year, and are expected to try again next year. The banking and finance industry have contributed more than $52,000 to Robb and more than $21,000 to Coleman.

The Virginia Auto Dealers PAC wants relief from local gross receipts taxes on automobile dealerships. It won pledges from both candidates to support what Robb called "a reasonable approach" in limiting the tax, which provides millions of dollars to local governments. The PAC has donated $70,500 to the candidates and their running mates, plus another $31,000 in free use of automobiles and office space.

Virginia's coal barons, the state's largest campaign contributors, have won pledges that both candidates will oppose new restrictions on strip-mining and any proposals for a state tax on coal sales. Coal industry sources have given about $250,000 to both Coleman and Robb.

VAMPAC executive director C.E. Douglas, who acknowledges that the eye-drop controversy was the only real difference his group found between Robb and Coleman, says the money VAMPAC donated buys only "an open door." Says Douglas: "There's only two groups of people most politicians will listen to and respect -- those who work for his election and those who contribute to his election."

Critics say the big money has a perverse effect on campaigns and candidates. "It's a danger to our whole political system," says Jane Reuss, chairman of Virginia Common Cause. "That much money pouring in can be easily abused." Reuss adds that public financing of campaigns, which her group supports, "will be a long time coming in Virginia."

The candidates themselves, while denying their own positions on issues are influenced by campaign contributions, are quick to accuse each other of pandering to interest groups.

Members of the Robb campaign first leaked Coleman's VAMPAC commitment to the press. Coleman, in turn, has charged that Robb's proposal to invest up to 20 percent of the state's retirement funds in mortgages was designed to reap campaign contributions from members of the ailing housing and real estate industry. Robb has received more than $241,000 from real estate interests, builders and contractors, more than double what Coleman has reported receiving.

Coleman denounced the Robb proposal as "Great Society-style social engineering," a position that Mark Saurs, chief lobbyist for the Virginia Savings and Loan League, says did not endear the Republican with savings and loan officials and home builders. While publicly neutral, Saurs attended a $5,000-a-couple Robb fund-raiser and is said to have boosted Robb to S&L executives around the state, who have contributed $16,000 to the Democrat.

Alson Smith, Robb's chief fund-raiser, concedes his candidate's retirement fund proposal helped him raise money in the business community. Says Smith: "I'd be foolish to say it wouldn't turn them on . . . and Coleman was foolish to smack them in the face."

Smith says the money was flowing in long before the proposal and contends Robb has made no promises in return for it. "Chuck's so clean, sometimes it scares you," says Smith.

Coleman spokesman David Blee concedes his candidate "lost considerable financial support from the savings and loans" because he opposed Robb on the retirement funds issue, one where he says Robb "clearly went over the boundaries" of propriety.

Blee says Coleman's promises to interest groups stem purely from his commitment to free enterprise, not from campaign donations. "It'd be unnatural for us to take positions that weren't good for the state's economy," says Blee.

Even in Virginia, however, some PAC money isn't good enough for all candidates. Gerald Baliles, the Democratic candidate for state attorney general, returned his share of a $3,500 contribution to the joint Democratic campaign from a Virginia Electric & Power Co. PAC. Baliles said the donation could result in a conflict of interest because the attorney general's office represents consumers at Vepco's rate hearings.

The campaigns give interest groups a chance to reward their friends and punish their enemies. The state's beer and wine wholesalers have been angry at Coleman since two years ago, when as state attorney general, his office launched an investigation of allegations of beer price fixing. They have contributed about $26,000 to Robb, even though Coleman eventually called off the probe.

"I don't think that's the only reason they gave to Chuck, but that controversy certainly aggravated the situation," said William G. Thomas of Alexandria, the beer wholesaler's lawyer and a top Robb adviser.

Unlike federal elections, PACs are not a major feature in Virginia campaigns. "A PAC just calls attention to itself," says one lawyer-lobbyist. "You can help someone just as effectively and a lot more quietly with individual contributions."