In a startlingly clear contrast, Americans pay a billion dollars more per year to the same company for a slightly different version of the same drug, an injection for wet macular degeneration. The outpatient treatments involve an injection directly to the affected eye, to stave loss of vision.

Genentech, a division of the Roche Group, charges $50 per treatment for Avastin, in comparison to $2,000 for its Lucentis brand treatment. With slight molecular differences, the drugs were tested side by side, and were both found protective in the eye condition. However, the more expensive drug offers potential financial incentive for doctors under Medicare pay rules, which allow reimbursement for up to 6 percent more than the cost of the drug.

Now, The Washington Post says, Genentech markets its pricier drug to doctors with rebates for a higher sales volume. Although the two drugs are both similar to produce, at a more or less equal cost, Lucentis costs 40 times more than Avastin. The more expensive drug is prescribed 44 percent of the time for Medicare patients. Moreover, the manufacturer has not sought regulatory approval for the cheaper drug, which some experts see as more or less equal. In response, the company defends Lucentis as “the most appropriate medicine” for the macular degeneration treatment, “specially tailored” for the eye. The drug has left an “immense impact,” the company said.

Moreover, Genentech’s parent company the Roche Group spends $9 billion annually on research and development. “The price of Lucentis supports the research and development of new potential medicines, including the 92 percent of drugs that never make it to patients,” the company said. “We re-invest a larger portion of our revenue into clinical research than most pharmaceutical companies. Genentech believes it is in the best interest of patients to continue to focus our efforts in ophthalmology on discovering and developing new potential medicines for other serious diseases of the eye.”

Yet J. Gregory Rosenthal, a Toledo Ophthalmologist, protests the prescription of Lucentis over the cheaper drug. “Lucentis is Avastin — it’s the same damn molecule with a few cosmetic changes,” he told The Post. “Americans are paying a billion dollars every year for no good reason — unless you count making Genentech rich.”

Rosenthal co-founded the group Physicians for Clinical Responsibility specifically to protest prescriptions for Lucentis. Within just Medicare, those prescriptions brought the company $1.2 billion in revenue, according to The Post. Tami Holzman, a spokeswoman for the U.S. Centers for Medicare and Medicaid Services, said the government lacked authority to “dictate treatment” based on cost, given a 2009 federal judicial decision barring discrimination among medications based on price. “Under current law, Medicare must cover treatment that is deemed reasonable and medically necessary by a physician or other provider.”

However, that freedom to prescribe… comes with a cost.