The Virginia Board of Health, faced with a soaring deficit in the state's Medicaid program, today adopted a series of across-the-board cutbacks that will restrict medical services to more than 263,000 of the state's poorest residents.

The new plan, which would cut program costs by $122 million during the next two years, comes on top of previously approved reductions that will eliminate about 12,000 recipients from the rolls starting July 1. While the new plan does not remove any additional recipients, it does affect all those under the plan by eliminating free access to such services as eye examinations, dental services, drug prescriptions and most hospital care.

"This has been one of the most horrendous jobs that has ever been perpetuated on this commonwealth in the six years I've been on this job," said board chairman Dr. Clarence W. Taylor after the meeting. He called the cutbacks agonizing, although necessary because of the state's financial problems.

Advocacy groups for the poor today charged that some of the more painful reductions could have been avoided had state officials attempted to find new funding for the program.

"It's the low-income people who are really shouldering the entire burden of the deficit problem," said Jill Hanken, lawyer for the Virginia Poverty Law Center. "There was no strong effort by anyone either in the General Assembly or the Board of Health to find more money for the program. Instead the entire emphasis from the beginning has been on cutting it."

Among the most severe cutbacks were:

* Medicaid patients, who now have unlimited access to physician and pharmaceutical services, would be restricterd to 12 visits to a doctor's office a year and six drug prescriptions per month.

* Nursing home residents who are hospitalized for more than 15 days would no longer be guaranteed of returning to the same home. Advocacy groups charge this would traumatize many elderly who would have to move to new homes after their illnesses.

* A broad range of previously free services would be replaced by "copayments" requiring the Medicaid patient to pay a share of the cost. Some of the payments would be as low as a $1 charge for dental visits, but others such as hospitalization for "nonlife threatening" illnesses, would be as high as $30.

Dr. W. Leonard Weyl, the board's vice chairman, said it was fantastic to expect indigents to come up with the $30. "We're not talking about face lifts here," he said. "We're talking about needed surgery."

The board gutted a proposal to eliminate coverage for Valium, a tranquilizer used by about 8,000 Medicaid recipients. Health officials had argued that the drug is highly abused, but the board had been swamped with letters from pharmacists as part of a lobbying campaign orchestrated by Hoffman-LaRoche Inc., the drug's New Jersey-based manufacturer.

Virginia's Medicaid deficit has been growing for several years, partly because of Reagan administration cutbacks and of increasing health care costs. State officials estimate they will lose $46.4 million in federal Medicaid funds during the next two years as a result of federal reductions. The rest of the state's two-year deficit -- an estimated $76.2 million -- has been caused by jumps in program costs of about 20 percent a year.

To face the problem, the state legislature directed the administration of Gov. Charles S. Robb to come up with the $122 million in reductions. Proposals by a Robb-appointed task force generated a storm of criticism.

Much of the outcry had been generated by the state's politically influential nursing home industry -- a lobbying effort that was strongly criticized by Bruce Kozlowski, state's new Medicaid director. "I've always objected to the use of elderly people to achieve an end," he said today. Virginia Medicaid "Life for these people is tough enough."

The industry's lobbying nevertheless appeared to have paid off. The board today adopted a less severe restriction than it had once proposed, one that would limit state reimbursements to about $39 per patient per day in Northern Virginia and $35 per day elsewhere in the state -- the average industry cost.

Robert Seiler, director of the Virginia Health Care Association, said the impact of the new formula was unclear but still onerous. "It's going to be awfully difficult for an awful lot of homes to provide the level of care," he said.