Why does a halo effect appear after laser correction of vision?

Nine out of ten patients who underwent laser vision surgery reported satisfactory results. But a significant percentage of patients experience new visual impairments. For example, they see halos around light sources up to six months after the procedure, according to a new study.

Side Effects of Surgery

"Although laser surgery has long been recognized as safe and effective, small, but a significant number of patients report such postoperative effects as glare, halos and other symptoms, and also speaks of dry eyes," said Dr. Christopher Starr. He is an assistant professor of ophthalmology in a hospital in New York.

"These effects tend to go away over time, either during the healing process, which can take up to 12 months, or they can be eliminated with additional procedures if necessary," said Starr, who did not participate in the new study.

Of the hundreds of patients surveyed, less than 1 percent reported an issue that affected their lives every day. Nevertheless, these problems can be more common than previously thought.

What problems are solved by laser surgery?

Laser surgery is used to treat problems such as nearsightedness and farsightedness, as well as astigmatism (eye disease, in which the perception of the image is distorted). Millions of patients who hoped to get rid of glasses or contact lenses have experienced laser surgery since it began more than 20 years ago.

To learn more about the consequences of this type of treatment, the US Food and Drug Administration has conducted two studies between 2011 and 2014.

Expert opinion

"Some of the problems described by patients included such debilitating symptoms as glare and halo effect, as well as dry eyes," said Dr. Malvina Eidelman, director of one of the FDA units and co-author of two new reports. According to her, daily activities and night driving were difficult for some patients.

Nevertheless, Eidelman and Starr said that the findings do not challenge the assumptions about the safety and effectiveness of laser surgery, since the studies were not intended to study these issues.

Researching

In one study, doctors examined the responses of 240 representatives of the Navy personnel one and three months after the operation. 50% of the respondents were young people.

In another study, the researchers analyzed the responses of 271 civilians, with an average age of 32 years. Their survey was conducted six months after they had been through laser surgery at one of the five centers in the United States.

Up to 46% of participants who had no visible symptoms prior to surgery reported that at least one visual symptom appeared three months after the operation.

Patients reported that the halo effect is most common. Up to 40% of participants without this effect before the operation was received it three months after it. In addition, up to 28% of participants without any symptoms of dry eye before the operation reported them three months later.

These data are consistent with previous studies, scientists say. Nevertheless, more than 90% of patients reported satisfactory results of the operation. And those who had complaints did not always seek help.

"Participants were more than twice as likely to report their visual symptoms during the interview, rather than talking about them to their treating doctors," said Adelman.

But it is not yet possible to say whether people of a certain age or sex can be more susceptible to these postoperative disorders.

Dr. Starr says that the questionnaire can be used to help researchers understand more deeply how laser surgery is related to vision problems that affect people's lives.

Risks and advantages

"Thanks to modern technological advances, probably there has never been a better time to agree to a laser vision correction," Starr said. He noted that a recent review of 4,400 clinical trials conducted between 2008 and 2015 found that patients received better visual results than ever before.

Nevertheless, laser surgery is not suitable for all patients who have impaired vision. There are some patients who prefer to stay in contact lenses or glasses, instead of performing laser vision correction. This indicates the importance of careful screening, as well as an open and honest dialogue between the patient and the doctor about the risks and benefits.