|"Now that it's been identified, it's great. When patients show signs, I can put a name to it."|
— Daniel S. Durrie, MD
A syndrome investigators are calling transient light sensitivity has been identified as a postoperative complication of IntraLase flap creation. The syndrome, which does not affect visual acuity, is seen in less than 1% of patients and typically resolves with a short, aggressive course of steroids.
Some users of the IntraLase femtosecond laser keratome first noticed the complication when they began working with the system more than 2 years ago. Since then, the phenomenon has gone under multiple names.
“Patients would walk into the office with two pairs of sunglasses on and a baseball cap,” said Brian R. Will, MD, director of Will Vision & Laser Centers in Vancouver, Wash. “No one knew what to make of the symptoms — light sensitivity, preserved visual acuity and no slit-lamp findings.”
Dr. Will coined the term track-related iridocyclitis and scleritis (TRISC) syndrome to describe the condition he thought was due to gas bubbles and debris migrating toward the limbus during LASIK with IntraLase.
Karl G. Stonecipher, MD, another early user of IntraLase, called the syndrome good acuity plus photophobia (GAPP). “It’s similar to the late-onset inflammation we once saw with PRK,” Dr. Stonecipher, of Greensboro, N.C., told Ocular Surgery News. He believed that the inflammation was due to activated keratocytes in the interface.
As time passed, speculation grew among users. Surgeons became concerned about the cause and identity of the rare aftereffect of IntraLase flap creation.
“It was scary when we didn’t know what it was — frightening to the surgeon and the patient,” said Daniel S. Durrie, MD, director of Durrie Vision in Overland Park, Kan.
Transient light sensitivity
In July, IntraLase surveyed users of its system and discovered that the apparent photophobia phenomenon was unique to LASIK cases using IntraLase for creation of the flap.
“Transient light sensitivity, or TLS, is the term coined by IntraLase to describe the complication,” Dr. Durrie said.
“Once TLS and an effective treatment for the syndrome were identified, it was a relief to everyone,” Dr. Will said. “It was hard to treat something when you didn’t know what in the world it was.”
“Now that it’s been identified, it’s great,” Dr. Durrie said. “When patients show signs, I can put a name to it, say, ‘Oh, you have TLS. This is a known condition. It responds to steroids, and then it goes away for good.’”
TLS symptoms manifest 2 to 6 weeks after surgery.
“Patients’ eyes appear fine. There is no visual acuity loss, diffuse lamellar keratitis, redness, dry eye or inflammation inside or outside the eye — just light sensitivity,” said Perry Binder, MD, of the GordonBinder Vision Institute in San Diego.
Photophobia can be mild to severe, depending on the duration of symptoms at the time patients present.
“When patients wait 3 to 4 weeks, photophobia is usually moderate and easily treated. But when they wait 6 to 8 weeks after first noticing the symptoms or the diagnosis is delayed, it’s usually much worse,” Dr. Will said. Light sensitivity typically occurs bilaterally and is more common in patients with blue irides, he noted.
Dr. Stonecipher noted a higher incidence of TLS among female patients. “There is a female preponderance of 75%,” Dr. Stonecipher said.
Along with normal visual acuity, patients’ anterior segments appear normal with no iritis, cellular flare, corneal staining or anomaly, episcleritis, or redness in the conjunctiva/sclera. Patients with severe photophobia may complain of pain on upward gaze, Dr. Will said.
Activated Keratocytes in the interface of a patient with TLS (top) vs. a normal (bottom) IntraLase patient with no TLS.
Images: Stonecipher KG
Surgeons have been treating patients with TLS according to what has proved most effective in the clinic.
“I find that combined topical and oral steroids work extremely well together,” Dr. Will said.
In patients with mild to moderate photophobia, Dr. Will prescribes topical prednisolone acetate four times daily for the first week and then tapers treatment to one, two or three times a day over a few weeks, depending on the severity of photophobia. For patients with severe photophobia, assignments of oral steroids (medrol dose pack or predisone) and topical prednisolone are required until symptoms improve.
“Most people agree that a short course of steroids is all that’s needed,” Dr. Binder said.
“The earlier you start patients on steroids the better,” Dr. Durrie said. The incidence of TLS may be lower in Dr. Durrie’s patients, about 0.2%, because he aggressively treats all LASIK patients with postoperative topical steroids, he said.
“I treat all my LASIK patients with Pred Forte (prednisolone 1%, Allergan) for the first week, four times a day, and this practice has really helped to decrease my incidence of TLS,” Dr. Durrie said.
“When someone walks in with a complaint of photophobia, we immediately hit them with topical steroids,” Dr. Will said. “We are treating patients more aggressively now that we know what the condition is. The biggest problem occurs when you ignore the symptoms or don’t treat it properly. Then it can be hard to control and might recur.”
Dr. Will said that patients rarely respond to topical or oral nonsteroidal anti-inflammatory drugs, cycloplegic agents or Restasis (cyclosporine ophthalmic solution 0.05%, Allergan). Dr. Stonecipher said Restasis has been helpful.
“Restasis decreases the time of resolution. I think that steroids help, but steroids plus Restasis help even more,” Dr. Stonecipher said. For patients with TLS, Dr. Stonecipher prescribes a dose of prednisolone four to six times per day for the first week or two after patients present with symptoms. This treatment is combined with drops of Restasis two to four times daily.
“I maintain patients on Restasis and take them off steroids for the next week,” Dr. Stonecipher said. “I start anyone else who complains of light sensitivity on Restasis as well because it speeds up the healing process.”
Gas bubble theory
The root cause of TLS is unknown.
Dr. Binder, co-medical director at IntraLase, said that company researchers are currently looking into possible causes of TLS.
“There are several possible theories,” he said. A likely theory, Dr. Binder said, is one that Dr. Will initially suggested: track-related iridocyclitis and scleritis.
“In unusual cases, the gas from the evaporated cornea escapes into the episclera over the ciliary body and creates irritation through the ciliary body. Surgeons see a gas bubble at the limbus and through the trabecular meshwork into the anterior chamber,” Dr. Binder said.
“Full applanation of the cornea drives a lot of gas into the cornea itself,” Dr. Will said. For this reason, he started promoting a partial applanation docking technique with IntraLase a few years ago.
During flap creation with IntraLase, gas and liquid are formed after laser energy dissipates into solid corneal tissue. The laser energy converts tissue into carbon dioxide, carbon monoxide and water. These materials and associated cellular debris are “forcibly injected” back through the corneal tissue, Dr. Will said.
“The gas creates a track, a little opening or tunnel, from the edge of the interface near the hinge out to the peripheral part of the eye near the limbus, where the trabecular meshwork and iris insertion is,” Dr. Will explained. “Inflammatory cytokines produced during tissue remodeling and healing of the flap gain access to this area and create inflammation in the wall of the eye. In my view, this is what causes the photosensitivity.”
He noted that by lowering energy levels, the amount of gas and liquid driven into the cornea toward the limbus can be reduced. “As energy levels go down, a smaller track is created and less material will funnel through that track,” Dr. Will explained. “We have definitely seen a decrease in the incidence and severity of TLS when we reduced our laser energy settings.”
“If we can lower the laser energy we can certainly avoid complications,” Dr. Durrie said.
High energy, activated keratocytes
"It's hard to say exactly what the cause is, but we are looking into all the possibilities to determine if the complication can be prevented in the future"
— Perry S. Binder, MD
Dr. Stonecipher has found that switching from the 10-kHz femtosecond laser keratome to the updated platform, a 15-kHz laser, has reduced his incidence of TLS. “My incidence is lower with the 15-kHz keratome,” Dr. Stonecipher said. “I’ve been able to reduce my side-cut energy.”
“The newer platform gives us a better dissection with less gas and with lower energy, and undoubtedly this is what causes most of the problem in the first place,” Dr. Will noted.
Dr. Stonecipher believes that laser energy power contributes to TLS, but that activated keratocytes in the interface are also to blame.
“Through confocal microscopy, I was able to witness activation of keratocytes in patients with TLS. Inflammation was accompanied with perineuritis,” Dr. Stonecipher said. He compared the confocal microscopy photos of patients with TLS to IntraLase patients who did not have TLS and saw a “marked” difference in images, he said.
“We are not sure if activated keratocytes are related to TLS or if they are just a normal feature of LASIK surgery,” Dr. Binder said. “It’s hard to say exactly what the cause is, but we are looking into all the possibilities to determine if the complication can be prevented in the future.”
Dr. Stonecipher said surgeons can improve their IntraLase outcomes by lowering laser energy, decreasing the amount of suction time and improving dissection with smaller spot separations.
“A lot of our problems were derived from our own inexperience and lack of knowledge about how to use the technology. Once you work out the treatment settings and surgical process and get your laser energy optimized, TLS occurs so infrequently, it’s hardly an issue anymore,” Dr. Will said.
For Your Information:
- Perry S. Binder, MD, can be reached at the GordonBinder Vision Institute, 8910 University Center Lane, Suite 800, San Diego, CA 92122; 858-455-6800; fax: 858-455-0244; e-mail: firstname.lastname@example.org. Dr. Binder is co-medical director at IntraLase.
- Daniel S. Durrie, MD, can be reached at Durrie Vision, 5520 College Blvd., Suite 200, Overland Park, KS 66211; 913-491-3737; fax: 913-491-9650; e-mail: email@example.com. Dr. Durrie is a clinical investigator for IntraLase.
- Karl G. Stonecipher, MD, can be reached at Southeastern Laser and Refractive Center, 3312 Battleground Ave., Greensboro, NC 27410; 336-282-5000; fax: 336-282-5022; e-mail: firstname.lastname@example.org. Dr. Stonecipher has a direct financial interest in the IntraLase femtosecond laser keratome. He is a paid consultant for IntraLase.
- Brian R. Will, MD, can be reached at Will Vision & Laser Centers, 8100 NE Parkway Drive, Vancouver, WA 98662; 360-885-1327; e-mail: email@example.com. Dr. Will has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- IntraLase Corp. can be reached at 3 Morgan, Irvine, CA 92618; 949-859-5230; fax: 949-461-3323; Web site: www.intralase.com.
- OSN Staff Writer Nicole Nader covers pediatrics and strabismus and neuro-ophthalmology in addition to cataract and refractive surgery.