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Silence Is Golden During IVT
It’s common practice to wear surgical face masks in the OR. Now a new study suggests that physicians should also cover up in the clinic, at least when giving intravitreal therapy injections (IVT).1
The study recruited 15 volunteers to play doctor by standing in front of open agar plates at a distance comparable to where they’d stand if giving injections. Then the volunteers read a five-minute script while masked, unmasked, and turned away from the plate without a mask. They also stood in silence for five minutes. Finally, they played patient, reclining in a chair and speaking with an agar plate secured to the forehead. A “room control” agar plate was positioned 3 m away from the action.
The study was inspired by a meta-analysis that implicated streptococcal bacteria in about one-third of postinjection endophthalmitis cases.2 (This compares to streptococcal organisms causing about 7 to 9 percent of postsurgical endophthalmitis.)
“The main goal [of our study] was to try to explain why we see more streptococcal organisms among all the endophthalmitis cases after injection compared with endophthalmitis following procedures performed in the OR,” said Colin A. McCannel, MD, associate professor of clinical ophthalmology, Jules Stein Eye Institute at the University of California, Los Angeles.
Dr. McCannel already knew that streptococcal organisms are common in the mouth. “I thought, maybe when people are speaking, they’re spraying saliva onto the field. Maybe that’s part of the explanation.”
This appears to be correct. Streptococcal species represented 66.7, 77.7, and 82.6 percent of bacterial colonies isolated in the face turned, no face mask, and reclined scenarios, respectively. In contrast, no streptococcal colonies developed in the setting of a face mask or silence (there was no statistically significant difference between the masked and silent groups). Still, the findings don’t prove cause and effect, as both the study’s authors and an accompanying editorial note.3 The editorial also projected that wearing a new 50-cent mask for every injection would cost the health care system $1.5 million.
Dr. McCannel dismissed the cost of the mask as negligible compared to a $2,000 Lucentis injection.
However, he acknowledged that the only true confirmation of cause and effect would be by comparing, through DNA fingerprinting, the flora from the doctor’s mouth to the bacteria that caused an infection.
Although the study didn’t confirm the surgeon’s use or nonuse of a face mask as a modifiable risk factor for the patient’s developing postinjection endophthalmitis, Dr. McCannel always wears one when giving an injection. To save time and hassle, he wears a face mask with loop straps that go around the ears, rather than one with straps that tie behind the head.
His technicians instruct patients to remain silent during the procedure.
“This study suggests we should have similar precautions in the clinic as in the OR, that is, wearing a face mask or at least not talking,” Dr. McCannel said. “No one questions wearing a face mask in the OR. But we thought we could ignore the concept of saliva droplet contamination in the clinic.” He added, “To me, the three seconds it takes to put on the face mask are well spent.”
1 Wen JC et al. Arch Ophthalmol.
2 McCannel CA. Retina.
3 Schimel AM et al. Arch Ophthalmol.
Dr. McCannel reports no related financial interests.
What’s Big, Gray, and Wears a Contact Lens?
Perhaps it would be hyperbole to call it a red-letter day in pachyderm history. But the news about the first elephant in Europe to wear a super-sized contact lens warmed many hearts this winter as it was picked up by newspapers, television newscasts, and websites around the globe.
The story started in late December, when Win Thida, an Asian elephant at the Artis Royal Zoo in Amsterdam, developed a painful, red, weeping eye. Zoo officials suspected that her cornea had been scratched by a tree branch while she played with other elephants.
After topical medications failed, the zoo called in veterinary ophthalmologist Anne-Marie Verbruggen, DVM. Her prescription for the 45-year-old elephant was the same one that a human patient might receive: a bandage contact lens.
A diplomate of the European College of Veterinary Ophthalmologists, Dr. Verbruggen used her experience with corneal injuries in horses to choose a jumbo therapeutic lens for the similarly sized elephant eye. She chose an equine lens made of polyxylon, with 74 percent water content, a diameter of 34 mm, and a base curve of 18 mm. That compares to a diameter of about 14 mm for bandage lenses meant for humans.
But before Win Thida—the matriarch of the Amsterdam herd—could become the first contact lens–wearing elephant in Europe, keepers had to spend most of January training her to accept ophthalmic intervention.
Finally, on Jan. 25, Dr. Verbruggen climbed a ladder, anesthetized the eye, debrided the ulcer, and used a forceps to place the extra-soft hydrophilic lens onto the elephant’s eye. “The main difficulty was her height. Elephants can’t lie down for long before their immense weight impairs their breathing, so I used a ladder to get close enough. It wasn’t ideal, but it worked. Win Thida seemed happier straight away,” she said afterward.
Because of the contact lens’ high gas permeability, Dr. Verbruggen knew it would be safe to leave the lens in place for up to four weeks. “The zoo vet checked Win Thida one week after we had applied the contact lens and still could see it,” she said. “I went back two weeks later and the lens was gone. So my guess is that the lens stayed approximately 10 days.” Her follow-up visit at five weeks showed a healed and comfortable, but damaged, eye. “There was a scar in the center of the cornea, which might be due to the age of the animal and might have been the trigger of the ulceration, but no more fluorescein uptake on the ulcer that I had debrided,” Dr. Verbruggen said.
Dr. Verbruggen reports no related financial interests.
Trends in Practice
Residual Astigmatism After Toric IOLs
After cataract surgery with toric lens placement, residual postoperative astigmatism can be a cause of poor uncorrected visual acuity. How do comprehensive ophthalmologists manage this problem when the intraocular lens (IOL) is properly aligned? In an Academy survey, nearly half of respondents prescribe glasses or contacts, slightly more than a quarter perform relaxing incisions, about one-tenth refer or perform PRK or LASIK, and a nominal percent exchange the IOL. The rest pursue none of these options.
These results are not at all surprising, said Douglas D. Koch, MD, professor of ophthalmology at Baylor College of Medicine in Houston. “Many surgeons who are implanting toric IOLs are not comfortable with relaxing incisions,” he said. And they would be particularly uncomfortable using them for an overcorrection, he added, because corneal astigmatism would necessarily increase as a result of the need to steepen the cornea further along the steep meridian. On the other hand, if the lens is properly aligned and the patient is undercorrected, adding relaxing incisions can be done with ease, said Dr. Koch.
“One also has the option of LASIK or PRK, particularly if there is residual myopia or hyperopia,” he said, “but any corneal approach to address an astigmatic overcorrection will result in increasing corneal astigmatism. Proceeding with PRK or LASIK is not unreasonable, although it is less optimal optically than exchanging the lens.”
However, exchanging the implant means entering the eye a second time. Doing so is apparently a rarity. “Most people think, ‘I’ve got one crack at it; otherwise, I’ll prescribe glasses,’” said Dr. Koch. “If there were significant overcorrection—over a diopter—I would be inclined to exchange the lens.” But if the overcorrection were minimal, he would instead opt for a relaxing incision, which might slightly increase corneal astigmatism while reducing the overall ocular astigmatism.
As for the survey respondents who would pursue none of these options? Dr. Koch said this is certainly a reasonable approach if residual astigmatism is minimal. “Hopefully, we’re not promising the patient perfection. Sometimes you just have to say, ‘I think we’ve done enough.’”
Dr. Koch is a consultant for Alcon and AMO.
CLINICAL PREFERENCES. To better understand current practices on a number of topics, the Academy surveyed comprehensive ophthalmologists about how they would handle various clinical situations. Each month, EyeNet will feature one question—this month about how frequently gonioscopy is repeated—and ask an expert to provide perspective on the responses.
Anticoagulants Safe for Diabetic Vitrectomy
Patients on anticoagulation and/or antiplatelet medications may safely continue using them while undergoing diabetic vitrectomy, according to a study conducted at Detroit’s Kresge Eye Institute.1
The retrospective study looked at 97 eyes of patients undergoing diabetic pars plana vitrectomy over the course of 30 months. Prior to surgery, 50 eyes (52 percent) were on anticoagulation (warfarin) and/or antiplatelet (aspirin and/or clopidogrel) therapy. Of those, 27 remained on medication, while 23 stopped an average of 9.3 days prior to surgery.
Tamer H. Mahmoud, MD, PhD, who performed all the surgeries, said that one might expect the use of anticoagulants and antiplatelets to increase the risk of surgery-related hemorrhage. Patients with proliferative diabetic retinopathy are already at risk of vitreous hemorrhage and even more so during or after vitrectomy. However, the study found no difference in the incidence of postoperative vitreous hemorrhage between the group remaining on medication and the group that stopped.
Although the outcomes were similar, the surgeries were not. To reduce the risk of retrobulbar hemorrhage, patients on warfarin or clopidogrel with or without aspirin (but not on aspirin alone) received posterior sub-Tenon anesthesia. Dr. Mahmoud, who is now associate professor of vitreoretinal surgery at Duke University, advised retina surgeons to do the same in these patients. The other patients received transcutaneous retrobulbar injection.
He also advised stopping a patient’s medication if the indication for use is of marginal value. Dr. Mahmoud discontinued his patients’ medication in consultation with the primary physician or cardiologist. “If they deemed patients to be at low risk of systemic complications secondary to stopping, then I did,” he said. “Otherwise, the patients continued their treatment.”
Both groups experienced a significant postoperative increase in visual acuity, but Dr. Mahmoud was surprised that the eyes on medication—which had less severe ocular disease at baseline—had significantly worse postoperative vision (best-corrected visual acuity of 20/230 versus 20/100).
Dr. Mahmoud speculated that may be because the group with the poorer outcome had to stay on medication, probably secondary to more severe systemic vascular disease. “Since diabetes is a systemic disease affecting many blood vessels, patients with systemic vascular disease may then be at higher risk of retinal damage, with possibly worse outcomes,” he said.
The bottom line: For some patients, the risk of discontinuing anticoagulation and antiplatelet therapy may be high, with severe systemic complications, Dr. Mahmoud said. “Therefore, retina surgeons should consider keeping their patients on those medications.”
1 Brown JS et al. Retina.
Dr. Mahmoud reports no related financial interests.
Omega-3 + Vitamin A Slows VA Loss in RP
Visual acuity (VA) decline can be slowed dramatically in adult patients with retinitis pigmentosa (RP) who follow a diet that includes one or two servings of fish a week and a daily vitamin A palmitate supplement, according to Eliot L. Berson, MD, and colleagues at the Massachusetts Eye and Ear Infirmary in Boston.1
“It is not complicated. It is simple,” he said. “We are talking about a card-deck-sized serving of tuna or salmon—or what some call oily fish—twice a week, along with this vitamin A supplement.” RP patients on this regimen are estimated to have, on average, 18 more years of sight than their counterparts, said Dr. Berson, lead author of the study and professor of ophthalmology at Harvard and director of the Berman-Gund Laboratory for the Study of Retinal Degenerations at the Massachusetts Eye and Ear Infirmary.
The study results are based on a compilation of food questionnaires that were completed annually by 357 RP patients in three randomized trials dating back decades: 1984 to 1991, 1996 to 2001, and 2003 to 2008. Patients were also followed with measures of visual acuity during the study periods. Notably, the first of these trials found that patients who reported taking vitamin A seemed to have more stable disease.
Analysis of the food questionnaires showed that disease progress was slower among those who liked to eat fish, too. Dr. Berson emphasized that “fish alone is not therapeutic; patients must also take vitamin A.” The researchers estimate that people who eat fish at least once a week and who had started taking the supplement by their mid-30s would not lose central vision until they are nearly 80 years old, in contrast to other RP patients on vitamin A eating less than one serving of fish per week, who would experience that same loss at about age 61.
Why do a couple of meals of cold-water fish weekly combined with daily vitamin A palmitate confer such protection against loss of VA in RP? The process isn’t fully understood, but it seems that omega-3 fatty acids from the fish help delivery of vitamin A to the remaining cone photoreceptors. Cones become depleted of vitamin A in RP, and the optimal dose of vitamin A seems to be 15,000 IU daily, Dr. Berson said.
1 Berson EL et al. Arch Ophthalmol.
2012; Feb. 13. [Epub ahead of print]
Dr. Berson reports no related financial interests.