BE SAFE Preventive measures such as disposable instruments and antibiotic prophylaxis are the best cure for complications such as endophthalmitis and TASS.

No matter how hard we try to make things perfect, we can't escape the fact that we live in an imperfect world. We see proof of this tenet every day in the world of cataract surgery and intraocular lens implantation. Even if a surgeon performs the procedure with the utmost precision and flawless surgical technique, an adverse event may occur.

Earlier this year, an American Academy of Ophthalmology Task Force, of which I am a member, issued definitions for 11 post-operative adverse events associated with premium intraocular lenses (osmag.net/KqM7Df) intended to reduce spectacle dependence — namely, chronic anterior uveitis; clinically significant cystoid macular edema; corneal edema; endophthalmitis; mechanical pupillary block; increased intraocular pressure; rhegmatogenous retinal detachment; toxic anterior segment syndrome (TASS); and 3 secondary IOL interventions (exchange, removal and repositioning).

Although some of these adverse events may occur in small numbers for reasons that are beyond a surgeon's control, the surgeon plays a key role in managing, if not preventing, many of these complications. For example, consider 2 of the most serious inflammation-related adverse events:

Endophthalmitis. This rare but potentially devastating infectious intraocular inflammation occurs in fewer than 1 in 1,000 cases. Barring a significant manufacturing glitch from a key supplier — as a reminder, rely only on accredited 503B compounders and reputable manufacturers that can provide proof of sterilization — the majority of endophthalmitis cases originate from ocular flora native to the patient's eyelashes and lid margins.

Prevention may be the best cure. Using disposable injectors, cannulas and phaco tips may decrease the infection risk, as should prophylaxis with antibiotics like intracameral moxifloxacin and careful incision management. Also, using a povidone-iodine-based product, both in and around the eye as a method of surgical prep, may be another reliable form of prophylaxis.

TASS. TASS is a noninfectious hyper-inflammation of the anterior segment and is most often caused by contaminants from improperly cleaned and sterilized instruments. Usually starting 24 to 48 hours after surgery, the inflammation usually results in hypopyon — the layering of white blood cells in the anterior chamber — and commonly presents with corneal edema that tends to improve with steroidal treatment. Additional surgical interventions may be necessary if the condition does not respond to steroids.

In the aftermath of the TASS outbreak from several years ago, in which unclean cannulas, phaco handpieces and other intraocular instruments were identified as potential sources, the industry benefited from a renewed emphasis on proper cleaning and sterilization. To this day, following the recommendations crafted by the American Society of Cataract and Refractive Surgery and the American Society of Ophthalmic Registered Nurses can help surgical facilities take proactive steps to eliminate any future TASS outbreaks (osmag.net/2GjdJA).

NEGATIVE DYSPHOTOPSIA
Can Anti-dysphotopic IOL Prevent ND?

PROGRESS Surgeons may soon have access to IOL designs capable of preventing negative dysphotopsia.

The buzz surrounding negative dysphotopsia (ND) continues to build, specifically regarding the tools surgeons may soon have to treat it. We continue to hear about progress being made in manufacturers' quest to build devices that may help to detect the presence or extent of ND.

Perhaps the most compelling advancement may come in the form of new IOL designs that can prevent ND from even becoming an issue. A small number of anti-dysphotopic IOLs have already come into play in Europe, one of which is the Morcher 90S IOL, derived from a U.S. patent. This IOL, which I developed and licensed, has a circumferential groove on the anterior optic that lets the optic overlap the anterior capsulotomy.

Although the lens is not yet available in the United States, it has earned the CE mark — Europe's version of FDA approval — and has shown strong initial clinical results: nearly 90 cases, from 3 months to 3 years, with no instances of ND.

— Samuel Masket, MD

UNAVOIDABLE Some adverse events associated with cataract surgery may occur for reasons beyond a surgeon's control.

Predicting the unpredictable
Although conditions such as endophthalmitis and TASS have generated more than their fair share of headlines over the years — you might say they warrant the attention, considering their potential to cause severe damage to a patient's vision — there's a lesser known complication worth exploring: pseudophakic dysphotopsia.

Categorized as either positive or negative, dysphotopsias are common visual complaints that arise after in-the-bag IOL implantation. It's almost impossible to predict which patients will be affected by these conditions, and in fact they tend to occur in cases where a surgeon performs the procedure without compromise in otherwise uncomplicated surgeries.

Positive dysphotopsias typically appear as arcs, halos or streaks of light, while negative dysphotopsias are perceived as dark, crescent-shaped shadows hovering in the temporal periphery of the visual field. Of the latter, some patients have said the visual effect makes them feels as if they're wearing horse blinders, or that they feel as though a presence is standing beside them, but when they turn around they see nothing there.

Of the 2, negative dysphotopsia (ND) is generally considered the more serious, as it tends to be more bothersome to the patient. It's also a particularly frustrating and time-consuming complication for the surgeon, because it doesn't present as any abnormality; it's strictly a patient-reported outcome. Therefore, solving the problem requires a "diagnosis of exclusion," meaning you must first rule out any other pathway to disease.

Solving the mystery
Until recently, the etiology of ND has been something of a mystery. Some suggested it was caused by light diversion or the corneal incision, while others attributed its origins to pupil size, retinal shape and lens position. Ray-tracing analysis and clinical findings have since confirmed that ND can be attributed in part to an optical interaction between an in-the-bag IOL's anterior surface and the anterior capsulotomy. The immediate post-op incidence of ND is in the range of 15% of IOL patients. In most cases, the condition resolves on its own relatively quickly, aided by pharmacologic pupil dilation, but as many as 3% of patients complain of chronic long-term ND.

So how do we correct the problem? We currently have a few surgical options at our disposal: exchange the IOL; place a secondary "piggyback" IOL; and perform a reverse optic capture, with the optic placed on top of the anterior capsule and the haptics still in the capsular bag. Based on some of the developments we've been seeing overseas, we may soon have some other alternatives available.

Practicing vigilance
Even under the best-case scenarios, research shows that "only" slightly more than 90% of patients are satisfied with their IOL after cataract surgery. In other words, as many as 7% to 10% of patients are dissatisfied with their lenses even when all other risk factors have been eliminated. ND or some other post-op complaint could be the source of this dissatisfaction.

This tells us that there are still some phenomena we don't fully understand. That's why, as clinicians, it's our responsibility to be vigilant and responsive to the needs of our patients. Such awareness will not only help us as surgeons to give patients the outcomes they seek, but also to rule out any retinal pathology that may lead to long-term vision loss. OSM