The main indications for refractive lens exchange (RLE) are high myopia or hyperopia with coexisting presbyopia. Other possible indications include presbyopia without ametropia and prepresbyopia with high ametropia in patients not amenable to keratorefractive surgery or phakic IOL implantation. RLE is therefore mainly performed in very short or very long eyes, and patient age is significantly lower in RLE compared with cataract surgery.

Strategies have been established to avoid postoperative complications of RLE, particularly posterior capsular opacification (PCO) and retinal detachment (RD). Despite advances in vitreoretinal surgery, severe vision loss is frequent after RLE complicated by subsequent pseudophakic RD. Almost half of patients who experience this complication end up with vision below reading acuity.¹

Preventing complications after an elective refractive surgical procedure such as RLE is paramount for patient satisfaction. This article reviews the incidence of PCO and RD after RLE and presents strategies for avoiding these complications.

PCO AFTER RLE

PCO, the most common long-term complication of phacoemulsification, has been reported to occur in 2% to 15% of eyes within 1 year and 2% to 63% within 3 years after surgery.^2-5 Although many factors associated with PCO development remain unknown, risk factors appear to include patient age⁶ and IOL design.⁷ A Cochrane Review published in 2010 showed a significantly lower PCO score in patients implanted with sharpedged IOLs (Figure 1); however, no difference between one- and three-piece IOL designs was observed.⁷

Additionally, no significant differences in PCO development were found between IOL materials (PMMA, hydrogel [hydrophilic acrylic], hydrophobic acrylic, or silicone); however, in this review, hydrophilic acrylic IOLs tended to have higher PCO scores and silicone IOLs lower PCO scores. Possible reasons for the higher rate of PCO with hydrophilic acrylic IOLs include the lens material itself and the less-sharp optic edges of these IOLs compared with those of hydrophobic acrylic IOLs.

Other risk factors for PCO that should be considered include a history of uveitis⁸ and pseudoexfoliation syndrome.⁹ In these cases, patients should especially be informed about their higher risk of PCO. Another aspect that should be considered is history of glaucoma, as a trend of higher PCO rates in glaucoma patients has been observed.¹⁰ However, these pathologies should play a minor role in the context of RLE, as they form relative or absolute contraindications for refractive surgery.

STRATEGIES TO PREVENT PCO AFTER RLE

Independent of the type of IOL implanted, RLE is associated with an increased rate of PCO in comparison with cataract surgery due to the relatively younger patient age.⁶ Based on the evidence available, only IOLs with sharp-edged designs are advisable in RLE, and a detailed informed consent is necessary.

An additional step that can be taken during surgery to prevent PCO is polishing of the anterior capsule to reduce the number of lens epithelial cells remaining in the capsular bag. The IOL should be centered in the capsular bag, and the size of the anterior capsulorrhexis should allow a complete overlap of the anterior capsule and the IOL optic.

A recent study showed a higher incidence of PCO among patients operated on by junior surgeons compared with those operated on by senior surgeons.¹¹ This difference was also attributed to the fact that the junior surgeons generated a larger mean capsulorrhexis diameter: 5.4 mm, compared with 5.2 mm for the more senior surgeons. Also of note in this study is that female sex was a predisposing factor for PCO development.¹¹ Another recent study reported that laser-assisted capsulotomy was associated with lower PCO scores than manual capsulorrhexis.¹²

Avoiding PCO is important in order to reduce complications associated with Nd:YAG laser capsulotomy. These include damage of the IOL optic, elevation of intraocular pressure, iritis, vitreous prolapse, induction of a posterior vitreous detachment, cystoid macular edema, and possibly RD. Published data suggest that the incidence of RD after lens surgery and subsequent laser capsulotomy varies between 0% and 4%.^13,14

It is worth noting that some authors postulate that the incidence of RD after laser capsulotomy is not due to the application of laser energy but rather to the opening of the posterior capsule. A direct correlation of RD incidence with mode, configuration, point of time after lens surgery, or level of applied energy for laser capsulotomy has not yet been substantiated. However, the risk of RD after laser capsulotomy increases significantly with the degree of myopia. Therefore, after RLE in eyes with early PCO and axial lengths (ALs) of more than 24 mm, one should carefully weigh the risks of laser capsulotomy against the benefit of some gain in visual acuity. In certain cases, it may be advisable to perform surgical polishing of the posterior capsule instead of using the laser in order to avoid opening of the posterior capsule.

RD AFTER RLE

The incidence of rhegmatogenous RD in the general population is 0.02%.¹⁵ The risk for RD development increases with myopia due to higher degrees of retinal and vitreous degenerations, posterior vitreous detachment, and retinal hole formation. Phacoemulsification also increases the risk of RD, and the combination of myopia and phacoemulsification significantly increases this risk. Intraoperative complications such as rupture of the capsular bag or vitreous loss elevate the risk of RD up to 8% even in the general population (Table 1).

Published data on the incidence of RD after phacoemulsification in myopes vary greatly, with rates ranging from 0% to 8.1% (Table 2).¹⁶ The majority of studies of this issue have a retrospective design. Comparing the differences of incidences of RD in the studies listed in Table 2, which represents a meta-analysis of studies examining this issue, one must note the wide variation concerning the various—and particularly older—operative techniques (eg, intracapsular and extracapsular cataract extractions), the patient’s degrees of myopia, and the length of follow-up. Additionally, microincisional surgery, laser-assisted cataract surgery, and IOLs with sharp optic edge designs were not available until recently. The incidence of PCO was higher in younger patient groups, and laser capsulotomy had to be performed more often in these groups.

There is an overall tendency for studies with an RD rate of 0% to have a follow-up time of less than 4 years and for studies with longer follow-up to indicate higher rates of RD. In order to estimate the real cumulative incidence of RD after RLE, long-term follow-up is mandatory, as it has been shown that the cumulative risk of RD (Kaplan-Meier analysis) after lens surgery increases in a linear fashion over time. For example, one study demonstrated that the risk of RD after small-incision coaxial phacoemulsification in high myopes (of note, both RLE and cataract surgery) was 0.47% after 3 months, 0.71% after 6 months, 1.71% after 15 months, 2.59% after 48 months, and 3.28% after 63 to 147 months.¹⁷ Therefore, one should consider the cumulative risk of RD for young myopes who undergo RLE as somewhat higher with respect to their significantly longer life expectancy.

The risk profile for RD after hyperopic RLE is completely different from that after myopic RLE. Hyperopic eyes exhibit a short AL and typically do not display any intrinsic retinal pathology. Thus, published data from several retrospective studies including 133 eyes have not shown a single case of RD after hyperopic RLE during follow-up of up to 6 years.^18-22

STRATEGIES TO PREVENT RD AFTER RLE

Risk factors for RD after RLE include high AL, age greater than 50 years, male sex, white race, existence of peripheral retinal degenerations, intraoperative complications, and postoperative application of laser capsulotomy for the treatment of PCO.¹⁶ Approaches to avoid RD target the last three items in this list.

The debate over the role of prophylactic peripheral retinal photocoagulation in myopes to prevent RD after lens surgery is lengthy. It is noteworthy that retinal hole formation may also emerge in clinically unsuspicious areas. The main arguments against prophylactic retinal photocoagulation are that an unnecessary and nonevidence-based therapy is inefficient and expensive and may cause later complications, including a higher incidence of macular pucker, macular edema, and posterior vitreous detachment. Finally, the question of whether prophylactic peripheral retinal photocoagulation is beneficial in high myopes cannot yet be answered based on the heterogeneity of the current, mostly retrospective published data. Indication is therefore still based on individual consideration of the patient’s age, degree of myopia, existing retinal degenerations, state of the vitreous body, and complication profile of the lens surgery.

Because the incidence of RD after myopic RLE increases with intraoperative complications, as displayed in Table 1, avoiding capsular rupture and vitreous loss is mandatory and the most important element of performing RLE in myopes.

Although the development of retinal holes and subsequent RD after laser capsulotomy has been described in the literature, novel data from recent studies show controversial results. In one study, no correlation between RD and laser capsulotomy was found.²³ However, there was a tendency for problems to occur if laser capsulotomy was performed very early after lens surgery.²³

SUMMARY

Strategies to prevent complications after RLE resemble those to prevent complications after cataract surgery. However, particular differences in patient age and underlying degree of ametropia translate to specific caveats.

Daniel Kook, MD, PhD, FEBO, is a Consultant in the Department of Ophthalmology, Ludwig- Maximilians-University Munich, Germany. Dr. Kook states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: daniel.kook@med.uni-muenchen.de.

Nino Hirnschall, MD, PhD, is a Resident at the Vienna Institute of Research in Ocular Surgery (VIROS), Hanusch Hospital, Department of Ophthalmology, Vienna, Austria. Dr. Hirnschall states that he has no financial interest in the products or companies mentioned.

Oliver Findl, MD, MBA, FEBO, is Director and Professor of Ophthalmology at the Hanusch Hospital, Vienna, Austria, and a Consultant Ophthalmic Surgeon at Moorfields Eye Hospital, London. He is the Founder and Head of VIROS, Hanusch Hospital, Department of Ophthalmology, Vienna, Austria. Dr. Findl states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: oliver@findl.at.

Thomas Kohnen, MD, PhD, FEBO, is Professor and Chairman of the Department of Ophthalmology at Goethe-University, Frankfurt, Germany and is a member of the CRST Europe Editorial Board. Dr. Kohnen states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +49 69 6301 3945; e-mail: kohnen@em.uni-frankfurt.de.

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