RETINA CLINICAL UPDATE

Vitreoretinal Surgeons: Keep an on the

s vitreoretinal surgeons know Diabetes. Vitreoretinal all too well, a surprise can arise surgery is safer for diabetic Aanytime during or after surgery patients than it used to be, —and it may be a substantial one. leading to fewer corneal and “A case that really hit home for me anterior segment complica- was a diabetic gentleman who’d had a tions than 20 years ago, said retinal detachment repaired elsewhere,” Jay Stewart, MD, at UCSF said Lisa S. Schocket, MD, at the Uni- Health in San Francisco. versity of Maryland in Baltimore. “As “Small-gauge instrumen- far as I could tell, the prior surgeon had tation with less dissection done a good job fixing the retina, but of the ocular surface makes the cornea had completely failed and surgery safer, creating less the patient’s vision in one eye was light post-op vascularization perception only.” When Dr. Schocket and irritation at the ocular attempted to fix a retinal detachment surface.” in the other eye, the entire epithelium However, he said, patients sloughed off, even though she hadn’t with diabetes have compro- touched the cornea—let alone scraped mised nerves and blood flow, it for better visualization of the retina. which can underlie some of COMPLICATION. Use care when repositioning a What went wrong? Although the the complications that may dislocated LASIK flap in order to avoid epithelial retina was free of retinopathy, diabetes arise, such as abnormal vas- ingrowth, pictured above. had devastated this patient’s cornea and cularization or nonhealing his vision. It’s a cautionary tale for vit- corneal epithelial defects. Dr. Schocket could be unstable,” he said. “To avoid reoretinal surgeons: You must also pay added, “Before going into the OR, be leakage through those incisions, it may attention to the condition of the cornea sure to take a thorough history.” be advisable to place sutures through to ensure an overall positive outcome. Aphakia. In aphakic patients, vitreo- the incisions prior to placement of the retinal surgery causes more turbulence trocars.” Remembering Risks to the of irrigation fluid flow at the corneal Prior refractive surgery. A LASIK Cornea endothelium, said Dr. Stewart, who flap wound never heals completely, Rahul S. Tonk, MD, MBA, is at the suggested application of a viscoelas- said Dr. Schocket, who’s experienced a Bascom Palmer Eye Institute in Miami. tic agent in the anterior chamber for dislocation twice. In fact, studies have He repeatedly sees corneal problems protection. shown that the strength of the healed following vitreoretinal surgery—from Recent incisions. Dr. Stewart also wound margin is on average only 28% infections to neurotrophic keratitis and suggests being mindful of corneal of the normal cornea.1 This can lead to epithelial defects. An important step for incisions from prior cataract or other flap dislocation during retina surgery. surgeons, he said, is to simply be aware anterior segment surgeries. “If the sur- “I’ve learned to specifically ask patients of patients who are at increased risk. gery was recently performed, incisions multiple times whether they’ve had LASIK, not just ,” she said, “because many don’t think of it as a BY ANNIE STUART, CONTRIBUTING WRITER, INTERVIEWING LISA S. surgical procedure.” (See sidebar,

Courtesy of Wuqaas Munir, MD, at University of Maryland. University at MD, Munir, of Wuqaas Courtesy SCHOCKET, MD, JAY STEWART, MD, AND RAHUL S. TONK, MD, MBA. “Dislocation of a LASIK Flap.”)

EYENET MAGAZINE • 29 When Neurotrophic Keratitis Occurs A degenerative disease characterized by Dislocation of a LASIK Flap decreased corneal sensitivity and poor If you’re not aware that a patient has a LASIK corneal healing, neurotrophic keratitis flap, you may inadvertently do things during (NK) makes the cornea susceptible to retina surgery to destabilize it, said Dr. Schocket. injury. “For example, if you’re placing viscoelastic jelly Because surgery can trigger or ex­ on the surface of the cornea and the wound is acerbate NK, it’s important for vitreo­ not perfectly sealed, the material can slowly retinal surgeons to discern which of ooze under the flap and loosen it.” The view to their patients already have it or to antic- the retina then becomes unclear, she said. Not ipate which patients may be predisposed realizing that this is due to a flap dislocation, STRIAE. Dislocated LASIK to NK, said Dr. Tonk. Patients at greatest the lead surgeon may scrape the cornea, which flap? Avoid striae with risk may include those with diabetes, as completes the displacement of the flap. proper repositioning. well as those—with or with­out diabetes Here’s how to avoid a LASIK flap dislocation. —who will undergo heavy endolaser Avoid a buckle. “I’ve only seen a dislocation happen with a buckle,” said photocoagulation for complex retinal Dr. Schocket. “It’s not always possible, but it’s best to try to avoid a buckle in detachments. In the latter scenario, “the patients with prior LASIK. During a buckle, viscoelastic material can potentially heavier or more confluent the laser, the seep under the flap and lift it off.” greater the risk of damage to the sensory If you must scrape. “If you need to scrape, do it carefully, starting from the long ciliary nerves,” he said. corneal apex and scraping toward the limbus,” said Dr. Tonk. “If you scrape As you look for NK, it’s important to from the limbus uphill toward the corneal apex, your blade may get under­ note that it has several stages. neath the LASIK flap, and you may inadvertently lift it.” Stage 1 NK may simply look like se- If dislocation occurs. Proper repositioning of the LASIK flap is critical to vere dry eye, said Dr. Tonk, except that avoid striae, irregular astigmatism, and epithelial ingrowth within the flap inter­ it doesn’t often respond to lubricant face. In addition, these must be watched carefully for diffuse lamellar drops alone. “Clues that you are dealing keratitis postoperatively. with NK include a diffuse pattern of Rinse the surface and interface thoroughly with BSS to wash away any punctate keratopathy and a swollen, released epithelial cells and prevent epithelial ingrowth, said Dr. Schocket. irregular epithelium, all of which can Then carefully reposition the flap, before completing the vitrectomy, which be responsible for several lines of de- may be more challenging now due to multiple interfaces. creased vision.” If the flap does not reposition smoothly into the stromal bed, Dr. Tonk Stage 2 NK is associated with re- advises the following: current or persistent epithelial defects 1. Remove the epithelium from over the top of the flap to reduce “bunching.” or delayed healing following epithelial 2. Use hypotonic saline or sterile water to swell and stretch out the flap. scraping, said Dr. Tonk. These defects 3. If all else fails, secure the flap with four to six sutures, but remove them are often bordered by rolled, loose within a few months to avoid inducing irregular astigmatism. edges of swollen epithelium. Stage 3 NK is characterized by a wherein the stroma may melt or even perforate. Surgeons should Protect nerves. Try to avoid laser diabetes or a LASIK flap, said Dr. investigate for melt when looking at photocoagulation at the 3 o’clock and Schocket. any epithelial defect, said Dr. Tonk. 9 o’clock meridians along the course of To reduce epithelial edema and This can be done easily with a thin, the long ciliary nerves. corneal clouding, Dr. Tonk noted that, high-powered slit beam or by obtaining Keep the cornea moist. A buckle to the extent possible, it’s important an anterior segment optical coherence can prolong the surgical time, which to limit surgical case time, infusion tomography scan. Even in the best case, increases the risk of the cornea drying pressure, and excess fluid volume melts are associated with corneal haze out, said Dr. Schocket. Viscoelastic passed through the eye (such as from and irregular astigmatism and can limit applied to the surface of the cornea leaky wounds). He added that surgeons final visual outcome. can help. “But if I’m concerned about can also use 50% glycerine to clear the a cornea in a person who had LASIK cornea via osmotic action, obviating Managing Corneal Challenges or has diabetes, I may let the resident the need to scrape. During and After Surgery do less, so I can speed things along.” If you must scrape to achieve ade- Although some may not heal as Avoid scraping, if possible. Don’t quate visualization, said Dr. Stewart, quickly as others, retina surgeons can scrape the corneal epithelium for visu- try to remove relatively small areas of take steps to lower the risks of corneal alization if you don’t have to, especially central epithelium. “A smaller epithelial

complications. high-risk patients such as those with defect has a better chance of healing in A. Goldman, MD. of David Courtesy of Ophthalmology, © American Academy

30 • JANUARY 2021 a shorter time. It’s not usually necessary 1. Place a bandage soft contact lens cornea specialist as quickly as possible to scrape the corneal epithelium out to at the time of surgery or the morning so you know you have the best chance the far peripheral portion of the cornea after. of healing the cornea.” where the limbal stem cells are located.” 2. Use preservative-free artificial tears. Alter post-op regimen. “A standard 3. Limit toxicity to the eye by modifying 1 Schmack et al. J Refract Surg. 2005;21(5):433-445. post-op regimen might include only a the use of eyedrops. For example, con- 2 Abdelkader H et al. Clin Exp Ophthalmol. 2011; visit on post-op day 1 and post-op week sider replacing glaucoma drops with an 39(3):259-270. 1,” said Dr. Stewart. “But patients who oral medication, reducing antibiotics required scraping should potentially to prophylactic dosing—typically two Dr. Schocket is a vitreoretinal surgeon and be seen more frequently to ensure the to four times a day—and reducing ste- associate professor, vice chair for clinical affairs, epithelium is healing and an infection roids to the minimum amount needed and chief of the retina division at the University is not developing.” to reduce inflammation. of Maryland, Department of Ophthalmology, in Don’t delay. “Surgeons must take 4. Consider punctal occlusion. Baltimore. Relevant financial disclosures: None. decisive action to promote rapid cor- Take aggressive steps—or refer. “If Dr. Stewart is a vitreoretinal surgeon and neal re-epithelialization,” said Dr. Tonk. the epithelium has not closed within professor of ophthalmology at the University Persistent epithelial defects that haven’t two weeks, treat aggressively as a per­- of California, San Francisco. Relevant financial healed within four weeks of surgery, he sistent epithelial defect,” said Dr. Tonk. disclosures: None. said, are frequently associated with cor- Surgeons might try autologous serum Dr. Tonk is a cornea specialist at Bascom Palmer neal haze and melt, or worse, infection eyedrops (available through a local Eye Institute and assistant professor of ophthal- or perforation. compounding pharmacy), temporary mology at the University of Miami Health System Speed closure. “If you have scraped tarsorrhaphy, amniotic membrane in Miami. Relevant financial disclosures: None. the epithelium,” said Dr. Tonk, “give (placed in the office or operating For full disclosures, see this article at aao.org/ your­self a strict timeline for partial room), or the use of Oxervate (Dompé), eyenet. and complete re-epithelialization— a nerve growth factor, to treat NK.2 within a week or two, at the most.” “But if you’re concerned about a MORE ONLINE. Learn about removal To speed closure, Dr. Tonk advises post-op problem with the cornea,” of corneal tissue from the vitreous cavi­ surgeons to do the following: said Dr. Schocket, “get it managed by a ty. See this article at aao.org/eyenet.

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EYENET MAGAZINE • 31