What technology is currently used in vision correction surgery?

In a procedure called photorefractive keratectomy (PRK), ophthalmologists use excimer lasers to ablate or burn away surface layers of the cornea—a transparent lens-like structure responsible for most of the eye’s focusing ability. PRK is approved by the FDA to correct nearsightedness and some forms of astigmatism by flattening the shape of the cornea. “However, the patient can experience temporary pain after surgery and recovery of normal vision is gradual taking anywhere from a few days to a few weeks,” said Alan Sugar, U-M professor of ophthalmology and a refractive surgeon at Kellogg Eye Center.

To speed recovery, a mechanical device can be used to cut a superficial flap in the surface layers of the cornea, which is then pulled aside giving the excimer laser access to deeper corneal tissue. “Since surface structures are not damaged in this LASIK procedure, it is relatively painless and vision returns more quickly,” Sugar explained. “This is a much more complex procedure than PRK. Because it relies on a mechanical device, there are risks of malfunction and associated occasional complications.”

What advantages will IntraLase lasers offer ophthalmologists and patients?

Currently, no laser can cut tissue within the transparent cornea without causing significant collateral tissue damage, according to Ron Kurtz, U-M assistant professor of ophthalmology and co-founder of IntraLase. Uultrafast lasers cut with greater precision, because they deliver energy in much shorter pulses lasting just a few femtoseconds. A femtosecond is one-millionth of one-billionth of a second.

Ultrafast lasers produce high surface quality cuts, and do not create large “shock waves” that can damage surrounding tissue, according to Tibor Juhasz, U-M associate research scientist and co-founder of IntraLase. U-M studies of corneal tissue cuts made with ultrafast lasers have shown significantly higher surface quality than cuts made with longer-pulsed lasers and fewer complications than are associated with mechanical cutting devices.

Ultrafast lasers are also being evaluated for other ophthalmic applications, including treatment of glaucoma and cataracts.

Tibor JuhaszU-M News and Information ServicesUniversity of Michigan