17 IOL Exchange
17.1 Introduction
High rates of dislocated intraocular lenses (IOLs) were the main reason that Sir Harold Ridley abandoned the posterior chamber implantation of the IOL after cataract removal in the 1950s. Modifications in IOL design as well as cataract removal techniques have led to the decreased rate of IOL complications but not eliminated them. Therefore, every anterior segment surgeon who places a lens should be aware of and comfortable with the steps for IOL exchange if that lens needs to be removed.
17.2 Indications for IOL Exchange
Many IOL complications can be managed by IOL repositioning or other less invasive surgical alternatives; those that cannot require IOL exchange. Primary indications for IOL exchange include IOL damage, IOL dislocation, patient dissatisfaction due to IOL-related symptoms, or refractive error (Table 17-1). 1
Reason for IOL exchange | Alternatives | Notes (other chapters) |
Optic or haptic damage | Observation, PPV for calcification | |
Refractive error | LASIK, PRK, piggyback IOL | See Chapter 10 |
Dysphotopsias | Reassurance, optic capture, piggyback IOL | See Chapter 14 |
IOL opacifications | None | See Chapter 13 |
Intrinsic IOL properties (multifocal IOLs) | Observation for neuroadaptation, correction of refractive error | See Chapter 12 |
Decentration and dislocation | IOL repositioning and fixation | |
Uveitis-glaucoma-hyphema | Medical management, haptic amputation | See Chapter 15 |
Abbreviations: IOL, intraocular lens; LASIK, laser in situ keratomileusis; PPV, pars plana vitrectomy; PRK, photorefractive keratectomy. | ||
Advances in refractive surgery options have reduced the range of ametropia that needs IOL exchange for management, and a variety of techniques discussed in this text for IOL repositioning and fixation strategies have reduced the need for IOL exchange for lens malposition.
Outcomes for IOL exchange are usually very good in regard to visual acuity; however, it is still a surgery that has an increased risk of complications compared to cataract surgery. Fortunately, there are many strategies to manage IOL complications that do not require IOL exchange today. A variety of these techniques and strategies are covered throughout this book.
17.2.1 Refractive Surprise
Postoperative refractive error, also called refractive surprise, can necessitate IOL exchange if the error is large, especially if the result is a hyperopic outcome. Chapter 10 discusses the common causes for refractive surprises; all significant errors warrant an investigation to determine the source for wrong IOL implantation, including wrong patient, wrong eye, or wrong calculations, because this can help identify a potential systemic problem in one’s practice.s. Literatur , s. Literatur , 4 It is important to place refractive surprise within the context of common modern outcomes. Even with correct IOL calculation and placement, ~ 55 to 74% achieve emmetropia 5 due to the limitations of current IOL calculations. 6 , 7 Lens calculations after corneal refractive surgery are particularly prone to calculation errors 8 , 9 and are discussed in Chapter 7.
In addition to IOL exchange, refractive surprises can be managed by glasses or contact lens wear, corneal refractive surgery (laser in situ keratomileusis [LASIK], photorefractive keratectomy [PRK]), and piggyback IOL implantation. Smaller refractive errors, especially myopic errors, may be best managed with corneal refractive surgery. 10 There is no absolute defined range, but in general, patients between − 4 diopters (D) and + 2 D often have this option. Beyond this range, lens-based surgery is usually required.
Lens-based surgery offers some advantages over corneal refractive surgery: it can treat a large amount of error, it does not change the anterior cornea, and it does not require special equipment, such as an excimer laser. LASIK and PRK are more accurate and allow treatment of both sphere and cylinder errors. Studies have compared IOL exchange versus corneal refractive surgery in patients, with more accurate results in the patient who underwent the latter. 7 , 11 It is especially useful to avoid IOL exchange when possible in a patient who has an open posterior capsule following intraoperative complication or who has undergone postoperative neodymium:yttrium-aluminum-garnet (Nd:YAG) capsulotomy.
Piggyback IOL placement is another alternative to IOL exchange for refractive surprise. 12 Piggyback lens placement may be easier than IOL exchange, especially if there is significant capsule fibrosis, which causes the IOL removal to be riskier. 7 Special IOL calculations are required to compensate for this second IOL; if IOL calculation error caused the refractive surprise, one must be sure that the same calculation errors do not occur. One study showed piggyback lenses to be safer than IOL exchange. 13 Complications of piggyback lenses include intralenticular opacification (Fig. 17.1), which may be prevented by aspiration of epithelial cells and enlargement of the anterior capsule.s. Literatur , 15 Piggyback IOLs can also lead to persistent anterior chamber inflammation, iris chafing and damage, increased intraocular pressure, and corneal decompensation (Fig. 17.2), requiring IOL explantation. 16 , 17
17.2.2 Dysphotopsias
Dysphotopsias are relatively common but frequently not bothersome enough to require management. Patients often describe dysphotopsias as a temporal arc of light, or dark, and frequently will draw a semicircular or moon shape in their peripheral vision as they describe their symptoms.
The etiology of dysphotopsias remains controversial and incompletely understood. Their discussion is the focus of Chapter 14. Theories of dysphotopsias include internal reflection, anterior or posterior edge glare of the optic, pupil size and location, and angle kappa. 18 Options for treatment include observation, reverse optic capture (Video 17.1), piggyback IOL placement, and IOL exchange. If IOL exchange is pursued, a variety of IOLs may be used, including three-piece silicone or one-piece polymethyl methacrylate (PMMA) IOLs placed within the bag or sulcus. Negative dysphotopsias are especially challenging and may not resolve, even with IOL exchange. 19
17.2.3 Intrinsic Multifocal IOL Properties Resulting in Patient Dissatisfaction
Although most patients are satisfied with their vision following multifocal IOL implantation, a small proportion are significantly dissatisfied and require aggressive management of their symptoms, even with uneventful surgery and good IOL positioning (Fig. 17.3). Chapter 12 discusses issues with presbyopia-correcting IOLs and presents a decision tree for management. Complaints can be generally categorized as blurred vision or photic phenomena (glare, halos, starbursts, or other related complaints). Posterior capsule opacification (PCO) and residual refractive error are the most common causes for unwanted symptoms, and both can be improved. 20 However, timing of complaints is critical; symptoms present immediately after surgery are not related to PCO, and symptoms related to refractive error should abate with correction.
Some patients may become less bothered by photic phenomena over time, although this has not been confirmed in studies. This “neuroadaptation” in multifocal contact lenses has been shown to take weeks to months for patients to fully adapt. 21 This presents a challenge, because IOL exchange is easiest within the first 3 months postoperatively and is the only absolute treatment for these induced photic phenomena. Significant photic phenomena on the first operative eye present additional challenges for the second eye. Most patients enjoy better functional acuity with bilateral implantation of multifocal IOLs. 22
17.2.4 IOL Damage (and Opacifications)
Damage to the IOL, including haptic damage, optic damage, or lens opacification, usually necessitates IOL exchange. Damage can occur during the primary surgery, after trauma, or after another surgery such as Nd:YAG capsulotomy or retina surgery. 23 , 24
Most minor IOL opacifications (termed glistenings) are not visually significant and do not require management (Fig. 17.4). Other symptoms, such as glare or dysphotopsias, may be apparent in the setting of minor opacifications. In these cases, management is directed toward treating photic phenomena rather than glistenings.
Lens exchange is usually warranted for true IOL opacification (Fig. 17.5). 25 Surface opacifications include calcifications and silicone oil adherence. There have been reports of vitrectomy being used to treat types of adherence. 26 Within the IOL, degeneration and calcifications can occur in hydrophilic IOLs, 27 which often cause glare and decreased vision. 27 , 28 Reports of opacification in these lenses after keratoplasty have also been a concern. 29
17.2.5 Uveitis-Glaucoma-Hyphema Syndrome
Although IOL materials are usually inert in the eye, uveitis-glaucoma-hyphema (UGH) syndrome may still rarely occur with modern IOLs. Chapter 15 discusses UGH syndrome in greater detail. Poorly manufactured IOLs of poorly fitting anterior chamber IOLs have traditionally caused UGH syndrome; with modern IOLs, the most common culprit has been one-piece foldable acrylic IOLs with haptics in the sulcus. 30
When a pseudophakic patient presents with iris defects postoperatively (Fig. 17.6), persistent inflammation, and/or increased intraocular pressure it is important to address the lens as a possible cause. Anterior segment ultrasound may aid the diagnosis. 31 , 32 If only one haptic is in the sulcus, amputation and removal of the haptic may alleviate the syndrome, although careful follow-up is required to assure full resolution of the problems (Video 17.2). A single haptic may also be rotated back into the capsule; however, this may be difficult due to capsular fibrosis. If these simple maneuvers are not feasible or successful, IOL exchange with a three-piece IOL appropriate for sulcus placement, iris fixation (if the iris allows), or scleral fixation is indicated.
17.2.6 Decentrations/Dislocations
The preceding chapter covers IOL malpositions extensively. Today, many IOL decentrations or dislocations can be repaired with IOL repositioning and do not require IOL exchange. One-piece IOLs, such as PMMA lenses, may be fixated to the sclera in select circumstances, 33 , 34 but, along with plate haptic designs, they are the most common IOL design requiring IOL exchange.
17.3 IOL Repositioning versus IOL Exchange
Regarding IOL repositioning versus exchange, the basic decision is this: if the IOL is currently implanted otherwise correctly but in the wrong position, attempt reposition (Fig. 17.7); if it is in some way defective, exchange it (Fig. 17.8). Some IOLs are not suitable for sulcus placement, iris fixation, or scleral fixation and are thus better managed by IOL exchange than reposition, even if there is no specific damage to the IOL. This group includes plate haptic IOLs and other IOLs without open loop haptic designs, such as the Crystalens (Bausch & Lomb, Inc.) (Fig. 17.9).
Studies have varied in regard to whether IOL repositioning versus exchange yields better results; however, much of this retrospective data is confounded by the complexity of a surgery requiring the latter. 35 , 36 In regard to outcomes, one study showed that IOL exchange in these patients improves uncorrected visual acuity and refractive error but not corrected visual acuity. 37
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