Is Laser Eye Surgery Safe?
For people with diabetes, its a matter of risk
I am not infrequently asked whether or not "laser eye surgery" is safe for patients with diabetes, and my answer has always been an unflinching "it depends." Here, I'd like to consider the pros and cons of such procedures specifically as they relate to patients with diabetes and, hopefully, defend my equivocal position.
First, it's important to know that there are two general categories of eye laser procedures: therapeutic and refractive. Therapeutic laser procedures are used to treat eye disease, such as severe diabetic retinopathy or glaucoma, with the aim of preventing or lowering the risk of permanent vision loss or blindness. Refractive laser procedures, by contrast, are intended solely to lessen a person's dependency on eyeglasses or contact lenses to achieve clear vision, and are used to correct extremely common optical (refractive) problems of the eyes like nearsightedness, farsightedness and astigmatism. Put another way, therapeutic laser procedures are medically necessary, whereas refractive laser procedures are not (i.e. the latter are, essentially, cosmetic). Given this important distinction, it's fair to say that the vast majority of questions patients have about "laser eye surgery" involve refractive laser treatments.
Several different laser refractive techniques currently are available, including PRK (photorefractive keratectomy), LASIK (laser assisted intrastromal keratomileusis) and LASEK (laser assisted epithelial keratomileusis). LASIK has become the technique of choice for most surgeons, but each has its own particular advantages and disadvantages. Each uses laser energy to reshape the cornea, the clear "window" at the front of the eye responsible for most of the eye's focusing ability (in essence, the precise curvature of the patient's eyeglass or contact lens is sculpted onto the cornea). Regardless of the particular technique (or laser) used, however, people with diabetes have increased risk of complications, especially complications involving the cornea.
High blood glucose weakens the attachments of cells on the front surface of the cornea, known as the epithelium. As a result, people with diabetes have a higher risk of corneal erosions -areas of the cornea where the epithelium episodically and, sometimes, painfully, comes off exposing nerve endings. Diabetic neuropathy can also impair sensation from corneal nerves, meaning that such corneal erosions may not cause pain, a phenomenon that increases the risk of infection and scar tissue formation.
Numerous studies have shown that the corneal epithelium of people with diabetes is much more fragile, and even minimal trauma (for example, eye rubbing) can tear off areas of the epithelium. Normally, the epithelium quickly regenerates and reattaches itself but, in diabetes, healing is slower and proper reattachment may never occur, resulting in a chronic cycle of erosions followed by imperfect healing followed by more erosions. This is one reason why it is riskier for people with diabetes to wear contact lenses; another is the fact that diabetes is associated with dry eyes, poor quality of tears and reduced ability of the eye to fight off infection. Refractive laser procedures increase all of these risks because they intentionally disrupt or remove the corneal epithelium. The bottom line: no patient with diabetes is an "ideal" candidate for laser refractive procedures. However, some patients with diabetes might be at least "reasonable" candidates.
June 5, 2016. Our Tour de Cure (New Jersey — Skylands) was nearly rained out. Rain, with periods of thunderstorms, was predicted all day. At the eleventh hour (almost literally! the email was timestamped 21:25 the evening before), the tour organizer notified us that the 100-mile route was being cancelled, but that riders could choose to ride the 66-mile course (or one of the shorter courses) instead. Just before midnight, the decision was made to have a rolling start for the...