From prostate surgery to gallbladder procedures, robots are already mainstays in the operating room. Now, they’re coming for your eyes.

In 2016, researchers from the University of Oxford’s Nuffield Department of Clinical Neurosciences kicked off a clinical trial to test the PRECEYES Surgical System, a robot designed to perform surgery on the retina, the surface at the back of the eyeball. On Monday, they published the results of their robot-assisted eye surgery trial in the journal Nature Biomedical Engineering.

A surgeon uses a joystick to control the mobile arm of the PRECEYES system. Doctors can attach various instruments to the arm, and because the system is robotic, it doesn’t suffer from any of the slight tremors that plague even the most steady-handed of humans.

For their trial, the researchers enlisted 12 patients that each needed a membrane removed from their retina — a fairly routine procedure, the study authors note. Doctors performed six of their surgeries the traditional way, while each of the others underwent a robot-assisted eye surgery.

The surgeries start with a tiny incision just above the pupil through which the surgeon inserts a flashlight. For the robotic version, the surgeon inserts the robot through an incision less than 1 mm in diameter, a bit below the pupil. It separates the membrane from the retina, then removes the membrane from the eye, exiting through the same hole it entered. In the surgeries conducted without the robot, the surgeon does this manually, using microsurgical instruments while looking through an operating microscope.

All 12 surgeries were successful; in some cases, the robot made the surgeon even more effective than usual, according to an Oxford press release. In a second phase of the trial, surgeons used the robot on three patients to dissolve under-retina hemorrhages that could have led to vision loss. Those surgeries were successful, too.

A robot-assisted eye surgery did take about three times as long as a traditional one, but trial leader Robert MacLaren told New Scientist that was just because the surgeons were unfamiliar with the robot and moved slowly out of caution.

Now that the researchers have evidence that they can use PRECEYES for routine procedures, they’re turning their attention to far more difficult surgeries — maybe even ones that are currently impossible.

“Our next step will be to use the robotic surgical device for precise and minimally traumatic delivery of a gene therapy to the retina, which will be another first-in-man achievement and is set to commence in early 2019,” MacLaren said in the press release.

While doctors can already perform that operation on patients who aren’t able to see at all, their hands aren’t reliable enough to pinpoint specific spots on the retina for  patients who still have some vision. MacLaren told New Scientist that PRECEYES might also allow surgeons to directly unblock blood vessels or inject treatments directly into patients’ optic nerves — two operations that are currently impossible.

PRECEYES is one of several robot surgeons in development, and while they generally may not work as quickly as their human counterparts, their precision will reduce the risk and open new doors to different types of surgery never before possible.