Surgical skills, informed consent required for IOL exchange
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IOL exchange remains an important surgical procedure for the consultative ophthalmologist.
In the 1980s and 1990s, gathering information from multiple sources and meetings, as many as 2% of IOLs implanted required removal and replacement. This was driven by the high number of closed-loop anterior chamber and iris-supported IOL implants placed after intracapsular cataract extraction in the 1970s and early 1980s that developed pseudophakic bullous keratopathy (PBK), iridocyclitis and cystoid macular edema, along with IOL subluxation and power misses in early-generation posterior chamber IOLs. In the last 20 years, there has been a decline in the incidence of IOL exchange but an increase in the absolute number as IOL placements have expanded. Most reviews place the incidence today at slightly less than 1%, but that still represents nearly 40,000 per year in the U.S. alone.
The most common reasons for IOL exchange have evolved over my 5 decades of practice. Today, total IOL subluxation or visually significant decentration, often inside the capsular bag, has become the new leader. Most of these patients have pseudoexfoliation or high myopia with weak zonules. The incidence can approach 2% of IOLs implanted in patients with pseudoexfoliation at 20 years after surgery. Elegant but somewhat complex surgical procedures have evolved for rescuing many of these patients with transscleral fixation techniques, but many cases still require removal and replacement.
IOL power errors, including wrong axis placement with toric IOLs, holds second place. Many of these power or axis errors can be resolved with corneal refractive surgery, IOL rotation or a piggyback IOL, but some still require IOL exchange. IOL opacification, especially with early-generation hydrophilic IOLs, requires IOL exchange when visually significant. Presbyopia-correcting IOLs come next, with some patients failing to neuroadapt, with complaints of poor quality “waxy” vision and unwanted visual symptoms, especially at night. Similar complaints of positive and negative dysphotopsias also persist in a small number of monofocal IOLs. PBK and endophthalmitis treatment sometimes require IOL removal or replacement.
A few personal thoughts after decades of dealing with these patients. First, visual outcomes are not as good for patients who require an IOL exchange or removal when compared with standard cataract/IOL surgery. Complications can and do occur, especially retinal complications, including cystoid macular edema (CME) and retinal detachment. PBK risk is increased, and some lenses subluxate or decenter again after repair.
Careful and well-documented informed consent regarding the surgical procedure risks is appropriate, and some patients will choose to adapt to their current IOL once they appreciate the risk of IOL exchange. It is especially important to show the patient with a presbyopia-correcting IOL what they will lose at near if the IOL is exchanged for a monofocal IOL. This can be demonstrated by placing a –2.5 D to –3 D loose lens over the eye as the patient reads. I have seen many patients decide to retain their current presbyopia-correcting IOL after this simple demonstration.
IOL exchange over an intact capsule is much safer and easier than with an open capsule. IOL exchange with an open capsule requires advanced skills, including comfort with pars plana vitrectomy.
For many, referral to a consultative ophthalmologist who performs IOL exchange frequently is appropriate. Peribulbar anesthesia for all but the simplest case is wise, and it is not unusual for the expected routine IOL exchange case to suddenly become complex. IOLs can be removed intact, cut into pieces or refolded inside the eye. The so-called scaffold approach popularized by the Agarwal team, in which the replacement IOL is implanted before removing the exchanged IOL, can enhance safety for some. More aggressive anti-inflammatory therapy with steroids and NSAIDs may reduce the incidence of CME and iridocyclitis. Dispersive and cohesive viscoelastics are both often helpful. If vitrectomy is required, the risk for retinal detachment increases significantly, and indirect ophthalmoscopy with scleral depression during or after surgery to discover and treat any retinal hole or tear is appropriate.
A broad array of surgical skills and proper preoperative and postoperative examination and treatment are required for the best outcomes in the more complex IOL exchange cases.
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