Phacoemulsification with implantation of an intraocular lens

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1 REVIEW ARTICLe : Monofocal and Multifocal, Their Applications and Limitations Bita Manzouri, MB BS, MRCP, FRCOphth, MD,* Maria-Laura Dari, FMH, FEBO,* and Charles Claoué, MA (Cantab), MD, DO, FRCS (Eng), FRCOphth, FEBO Abstract: Supplemental intraocular lenses (IOLs) have been developed to replace IOLs designed for in-the-bag placement being used as piggy-back IOLs in the sulcus due to unacceptable complications. The new IOLs have unique platform designs to avoid these complications. As a result, a new nomenclature is needed to describe the 4 scenarios when supplemental IOL use is now indicated. Key Words: supplemental intraocular lenses, IOLs, piggyback (Asia-Pac J Ophthalmol 2017;6: ) Phacoemulsification with implantation of an intraocular lens (IOL) is one of the most frequently performed surgical procedures in current clinical practice. Advances in phacoemulsification techniques, a wide range of available IOLs, and accurate IOL calculation formulae allow clinicians to aim for optimal refractive outcomes. However, despite all the advances in modern phacoemulsification surgery, postoperative refractive surprises (residual hyperopia, myopia, and/or astigmatism) still occur, leading to unhappy patients and physicians and the possibility of medico-legal cases, especially in refractive lens exchange (RLE) patients. The management of post-phacoemulsification residual refractive error is therefore a challenge that every surgeon needs to be prepared to deal with and resolve. 1 In modern practice, 3 different approaches are available for this problem. The first is an IOL exchange. 1,2 This procedure is best performed early in the postoperative course before the capsular bag has formed adhesions that essentially lock the IOL into place. Hence, this option works best when the surgeon feels that the existing lens implant can be safely removed and yet can still preserve an intact capsular bag. Potential complications include posterior capsular rupture and zonular dialysis that can destabilize the lens implant. However, there are 2 potentially disastrous scenarios here. The first is where there is substantial damage to the zonulo-capsular complex, meaning that a premium IOL (toric or multifocal or both) cannot be fixated with certainty. In extreme cases where there is no support at all for a posterior chamber capsular-fixated IOL, then a separate operation for a scleralor iris-fixated or angle-supported IOL would be needed. The From the *Department of Ophthalmology, Queen s Hospital, BHR University Hospitals; Institute of Health Sciences, Barts & The London School of Medicine & Dentistry, Queen Mary University of London; and 119 Harley Street, London, England. Received for publication March 15, 2017; accepted May 29, The authors have no funding or conflicts of interest to declare. Reprints: Charles Claoué, 119 Harley Street, London, England. E mail: charles@ dbcg.co.uk. Copyright 2017 by Asia Pacific Academy of Ophthalmology ISSN: DOI: /APO second scenario is where the refractive surprise has arisen because of mislabeling of the original IOL implanted. This occurs occasionally, although manufacturers have high levels of vigilance. As an example, suppose the biometry for a RLE patient shows a diopter (D) IOL should be used; this is the power implanted, but although the packaging states the IOL power to be D, its true power is D and a myopic refractive surprise results. The surgeon reviews the biometry, cannot see an error, and uses the original biometry and postoperative refraction to calculate what they think the correct IOL power would be to produce emmetropia; say D for simplicity. However, after an IOL exchange for D, because this time the power of the IOL was the same as that on the packaging, the patient now has a hyperopic refractive surprise and is likely to lose faith in their surgeon. These 2 scenarios can be avoided by the other 2 options for managing refractive surprises. The second approach for managing a refractive surprise would be a keratorefractive surgical procedure with the excimer laser [ie, laser-assisted keratomileusis (LASIK), photorefractive keratectomy (PRK), and arcuate keratotomies (manual or laserassisted)]. 1,3,4 These surgeries are best accomplished when the refractive error is stable and the corneal shape is completely normal. Laser ablation is not a viable option in patients with abnormal corneal topography or preexisting higher order aberrations. 5 This option obviously demands easy access to an excimer laser facility. The third option is the insertion of piggyback IOLs. 6 Patients generally experience rapid visual rehabilitation and excellent refractive predictability after a piggyback IOL. With the lens insertion into the ciliary sulcus, the capsular bag is preserved and the chance of vitreous loss significantly decreased compared with an IOL exchange. 7 We will discuss the use of these IOLs in detail below. As the supplemental IOL power is only based on the refraction and a vergence calculation, the true power of the first IOL does not need to be known. As an additional option, more recently light-adjustable IOLs [Light Adjustable Lens (LAL); Calhoun Vision] have been used to enhance post-phacoemulsification refractive errors. 1,8 The LAL lens is a 6.0-mm square-edge lens made of customizable silicone. During the postoperative adjustment, the surgeon uses an ultraviolet (UV) light to treat a specific area of the lens depending on the refractive goal. However, this technology is not widely available and the digital light delivery system used with the LAL is expensive (~ 120,000). 9 Patients may also find wearing UV-blocking spectacles until the second part of their treatment irksome. History of Polypseudophakia Polypseudophakia means the presence of more than 1 IOL in an eye. Implanting 2 IOLs at the time of lens removal is Asia-Pacific Journal of Ophthalmology Volume 6, Number 4, July/August 2017

2 Asia-Pacific Journal of Ophthalmology Volume 6, Number 4, July/August 2017 primary polypseudophakia; secondary polypseudophakia is where an additional IOL is inserted at a later stage in front of the first one. The practice of polypseudophakia has been accepted for more than 20 years. The initial usage of this technique was for extreme hyperopia when a single IOL could not provide enough optical power. However, surgeons also started using the technique for cases of refractive surprise, but it was found that implanting a standard IOL in a different anatomical position than for which the design of the lens was intended was the cause of complications (pigment dispersion, glaucoma, hyperopic defocus from the contact area when 2 biconvex IOLs were used, and pupil capture). Therefore, given the potential applications of polyspeudophakia and the problems with standard design intraocular lenses, companies have manufactured IOLs with platforms specifically designed for sulcus placement: supplementary IOLs. The first piggyback IOL procedure was described more than 20 years ago by Gayton et al 10 in a case of cataract and microphthalmos in which the calculated IOL power was +46 D. The authors reported the insertion of 2 IOLs at the same time to create an optic with sufficient plus power for a microphthalmic eye. This approach described in 1993 was followed by others and piggyback IOLs gained broad use for the correction of high hyperopia and myopia. 2,6,10 14 A few years later, in 1999, Gayton et al 6 reported good visual outcomes with secondary piggyback IOL implantation in the ciliary sulcus of pseudophakic eyes used for the correction of postcataract ametropia, outlining the advantages of this technique over IOL exchange, which was the only available treatment until that time. The former is less traumatic, carries lower risks of both operative and postoperative complications, and postoperative refractive results are more predictable. 15 In Gayton s cohort, the IOL powers were selected based on the postoperative spherical equivalent refraction, without taking into consideration the axial length and keratometry. Minus power IOLs were selected for patients with myopic refractive error and hyperopic patients received plus power IOLs. Subsequently, other IOL calculation formulae were proposed by Holladay et al 11 and Gills 14 for myopic and hyperopic eyes, respectively, which were proved to give more predictable refractive outcomes. The first piggybacked multifocal IOL the Array (Abbott Medical Optics Inc, Santa Ana, California; no longer available) was described by Mejía in Two years later, Donoso and Rodríguez 17 reported on a series of 5 patients implanted with the Array. They concluded that piggyback IOL implantation with a multifocal lens was a safe and efficient procedure that yielded good refractive results, although during this period the complications of sulcus placement of IOLs designed for capsular fixation were not yet recognized. More recently, surgeons have described the use of piggyback IOLs to lessen patients complaints of negative dysphotopsias after cataract surgery. Masket and Fram 18 have demonstrated that a piggyback lens implant anterior to the anterior capsular edge reduces patients complaints of negative dysphotopsia. Potential Complications of The most serious vision-threatening complication of piggyback IOLs is opacification between the optics of the 2 lenses, known as interlenticular opacification (ILO) when both IOLs are placed within the capsular bag, although this technique is not contraindicated. This complication has also been reported to cause a hyperopic shift, although this is probably due to deformation due to contact between the 2 optics, and may be accentuated from opacification in the space between the 2 IOLs. 23 Initial studies suggested that ILO was particularly seen when both IOLs (especially acrylic lenses) were implanted in the bag through a small capsulorrhexis. 20 Although the exact cause of ILO is unknown, it is postulated that bioadhesion of the anterior lens to the anterior capsule and the posterior lens to the posterior capsule may prevent cell migration from the equatorial bow to the posterior capsule. This migration may be directed toward the interlenticular space, resulting in ILO. Interlenticular opacification usually develops 6 months to 2 years postoperatively and may be responsible for reduction in visual acuity consequent to the induced hyperopic shift. 23,24 Different types of opacification have been described, with the most common being the formation of Elschnig pearls, arising from retained/proliferative lens epithelial cells. Histopathological examinations performed in some cases after IOL explantation have revealed that epithelial cells were mixed with cortical lens material. 19 Incidence of ILO was found to be higher when acrylic IOLs were used compared with polymethylmethacrylate (PMMA) IOLs. 2,22 A different type of ILO with brown pigmented deposits surrounded by Newton rings was also described by different authors, appearing as early as 2 weeks postoperatively. 2 To address this matter, Gayton et al, 19 Shugar et al, 21 and Spencer et al 22 proposed sulcus rather than in-the-bag piggyback IOL implantation when possible, meticulous cortical cleanup, and creation of a relatively generous capsulorrhexis to sequester retained cells peripheral to the IOL optic by fusion of the anterior and posterior capsules. Although implanting the second IOL in the ciliary sulcus has been proposed to reduce the risk of ILO and specially formulated IOLs that are designed specifically for sulcus insertion are now available, there are still several potential postoperative complications that must be monitored. This positioning of the IOL has been correlated with pigment dispersion syndrome and glaucoma, 25 caused by the rubbing of the haptics and the sharp square edge of the IOL against the posterior surface of the iris. Pupillary block, microhypema, or secondary glaucoma have also been described, 26 hence why some surgeons advocate the creation of a peripheral iridotomy (PI) at the time of secondary lens insertion. We recommend that a PI should always be considered, especially in short eyes. Piggyback IOL rotation, decentration, and tilt have also been described. A reported 10-degree tilt of the anterior IOL in a polypseudophakic eye was shown to significantly reduce image quality at spatial frequencies as low as 3 cycles per degree. 13,27 Techniques of Polypseudophakia Although polypseudophakia was originally called piggybacking, we have reservations about the continuing use of this term. Although it is easily understood, the original descriptions were with the use of IOLs designed to be in the capsular bag. As such, if the 2 IOLs were implanted in the bag, there was the risk of ILO and a hyperopic defocus where the 2 biconvex IOL optics touched and caused mutual deformation. If 1 of the IOLs was placed in the ciliary sulcus, the square edge risked causing pigment dispersion with resultant secondary glaucoma. We therefore prefer the term supplemental IOL to designate IOLs specifically designed to be implanted in the sulcus in addition to 2017 Asia-Pacific Academy of Ophthalmology 359

3 Manzouri et al Asia-Pacific Journal of Ophthalmology Volume 6, Number 4, July/August 2017 a capsular-fixated IOL. There are essentially 4 current techniques for the practice of polypseudophakia 28 ; they are summarized as follows. Primary Duet Procedure This involves the primary implantation of 2 IOLs at the time of the primary procedure. One IOL is placed in the capsular bag and 1 IOL in the sulcus. This can be used to treat eyes with extreme refractive error (when biometry is less accurate) such has high myopia, high hypermetropia, or high astigmatism that cannot be that fully corrected using a single, commercially available IOL positioned in the capsular bag. In this setting, it would be possible to split the total refractive power between 2 IOLs while maintaining a small incision size, although the split is unlikely to be equal. Under these circumstances, any resultant refractive surprise (as is more common with these eyes with high preexisting refractive errors) can be treated by simply exchanging the supplementary IOL. These same principles can be used with post-lasik eyes, where biometric calculations are also less accurate, and eyes with a cataract secondary to silicone oil in situ where the refractive status of the eye will change once the silicone oil is removed. Keratoconic eyes or eyes after penetrating keratoplasty often have high astigmatism that would need additional toric correction with a supplementary IOL. Recognizing the possibility that these eyes may need a future repeat graft procedure leading to a change in astigmatism, a purely spherical lens should be implanted in the capsular bag and the supplementary IOL, carrying all the toricity to correct the astigmatism, should be placed in the sulcus. Caution is advised if there is significant possibility of the patient requiring a rigid contact lens postoperatively, as this would render the astigmatism manifest again. The other use is for patients who wish to have their presbyopia treated. Presbyopic lens exchange (PRELEX) can be performed as a primary duet procedure with a capsular-fixated monofocal IOL targeted on emmetropia and a plano multifocal IOL to provide presbyopia correction. Performed as a presby-duet procedure, the patient has the opportunity to experience multifocal vision. If this is not tolerated after a suitable period of neuro-adaptation (which should be at least 3 months), then it is easy to remove only the sulcus multifocal lens (a duet deconversion procedure as explained below); the eye has then effectively had a monofocal refractive lensectomy. It should be noted that this is the only effective reversible surgery for presbyopia. Secondary Duet Procedure This can be the secondary implantation of a supplemental IOL to treat pseudophakic refractive surprise. Appropriate IOL powers are used to correct any residual spherical refractive error and any significant astigmatism. However, a secondary duet procedure can also involve the secondary planned insertion of a supplemental IOL as part of the optical management of a patient. In children over 1 year of age, IOL implantation is an accepted procedure with the IOL being implanted in the capsular bag, with emmetropia the aim of the postoperative refraction. 29 However, as the child s eye grows with age, it becomes increasingly myopic. In this instance, duet implantation can be used to avoid this myopic shift. In pediatric duet implantation, the power of the first lens (placed in the capsular bag) is calculated to ensure the child is emmetropic once the eye is fully grown. The supplementary lens is then implanted in the sulcus on top of the conventional lens to provide an opportunity for the child to reach emmetropia. As a result, the child has good refraction both immediately after surgery and as the eye grows. To keep the refraction stable as the eye grows and becomes more myopic, the supplementary IOL can either be removed or exchanged for another lens (duet deconversion procedure as explained below). Although duet implantation is very new, it may be the answer to the myopic shift in the growing eyes of children and may improve amblyopia management. Duet Conversion Procedure For patients who have decided that they want to be completely spectacle independent after monofocal IOL cataract surgery, it is also possible to use this procedure to insert a plano multifocal supplementary IOL into the eye, thereby converting the eye from having monofocal to multifocal optics. Similarly, patients can also be converted from emmetropia to monovision by having a supplementary lens inserted into 1 eye, again to make them spectacle independent. In other words, these are secondary procedures where the supplementary IOL is used to convert the optics of patients with existing pseudophakic eyes. Duet Deconversion Procedure A modern supplementary IOL allows postoperative refractive manipulation by removal of a supplemental IOL. It would be advisable to avoid using the word explantation because the removal (or exchange), in these cases, is either planned or recognized as a possibility for overall management in contrast to conventional IOL explantation scenarios. The term that is preferable is duet deconversion because, in some circumstances, an eye is converted from polypseudophakia to monopseudophakia. This duet deconversion technique can be considered in several potential scenarios, such as an eye that requires silicone oil for a retinal detachment repair (which becomes hypermetropic depending on what type of silicone oil was injected). If oil removal is uncertain, a supplementary IOL can be implanted simultaneously with the injection of silicone oil; subsequent duet deconversion can be performed if the oil is later removed. Another example is patients who require spectacle independence but are concerned about potential halos from multifocal IOLs. A presby-duet procedure a monofocal IOL targeted for emmetropia implanted in the capsular bag and a plano/multifocal supplementary IOL implanted in the sulcus can provide patients with good vision after neuroadaptation. However, for the small minority who prefer absolute presbyopia, duet deconversion, by removing only the supplementary IOL, results in what we would call a monofocal refractive lens exchange. Lastly, pediatric cataract cases can benefit from a duet deconversion procedure (as alluded to above), as 2.00 D the approximate ideal refractive outcome to minimize amblyopia in childhood produces unacceptably high myopia later in life when the IOL is left in the eye. On the other hand, after implanting a capsular-fixated IOL powered for adult emmetropia and a supplementary IOL with the remaining power as part of a primary or secondary duet procedure, the supplementary IOL could be removed (duet deconversion) when the child grows up. Manufacturers of Supplemental IOLs Secondary supplemental IOLs are currently available as monofocal, toric, multifocal, and multifocal toric models. To date, there are 3 manufacturers of IOLs specifically designed for 2017 Asia-Pacific Academy of Ophthalmology

4 Asia-Pacific Journal of Ophthalmology Volume 6, Number 4, July/August 2017 secondary implantation in the ciliary sulcus to correct pseudophakic refractive surprise or pseudophakic presbyopia: the Sulcoflex lens by Rayner (the first to be commercially available), the Add-On lens by HumanOptics, and the 1st Add-On by 1stQ GmbH. A more recent model, the A4 Addon IOL from the Medicontur family, has recently been tested in cadaveric eyes. 30 The implantation of the secondary IOL in the ciliary sulcus has an important advantage over the classic implantation of both IOLs in the capsular bag, which is to increase the distance between the 2 IOLs, thus reducing the possibility of ILO. 6,21,31 In general, supplementary IOLs are hydrophilic and include a number of design features to avoid complications associated with implantation in the ciliary sulcus. The convex-concave configuration of the optic helps to further increase the space between the 2 IOLs (placed in the bag and sulcus, respectively) and contributes to avoiding the possibility of any ILO and the induced refractive errors and optical aberrations. They have a large optical diameter to avoid the capture of the IOL during pupil dilation. They have rounded edges to reduce the risk of contact between the IOL and posterior iris, so as to diminish iris irritation and consequently pigmentary dispersion and secondary pigmentary glaucoma. They also have a 10-degree posterior angulation to minimize the risk of contact with the pigment epithelium of the iris and to ensure central positioning and rotational stability of the IOL. Research conducted by McIntyre et al 32 on cadaver eyes demonstrated that for haptics, a 10-degree angulation helps to maintain the necessary distance between the front surface of the IOL and the posterior surface of the iris, even if the supplementary IOL haptic shifts forward consequent to excessive proliferation in the capsular bag (Soemmerring ring formation). The Sulcoflex IOL The Sulcofex IOLs (Fig. 1) are single-piece lenses made of a hydrophilic acrylic material (Rayacryl) demonstrated to have high uveal biocompatibility. The IOL optic has a large, 6.5-mm diameter that covers the whole circumference of the capsular bag IOL and reduces risks of pupillary block and photic effects. The optic also features round edges to reduce dysphotopsia risk and a concave posterior surface to avoid contact with the capsular bag IOL and induction of hyperopic defocus. 33 The undulated 14.0-mm haptics optimize IOL centration and rotational stability and a posterior haptic angulation of 10 degrees prevents iris touch and contributes to uveal clearance. Round haptic edges also reduce the risk of iris trauma. There are 3 types available: the Sulcoflex Aspheric (653L), in which the sphere range varies in 0.50 increments between 5.0 D and +5.0 D, the Sulcoflex Toric (653T), in which the spherical equivalent range varies in 0.50 increments between 3.0 D and +3.0 D and the cylinder range varies in 1.0 D increments between +1.0 D and +3.0 D, and the Sulcoflex Multifocal (653F), which has an addition of D (equivalent to +3.0 D at the spectacle plane) and in which the sphere range varies in 0.50 steps between 3.0 D and +3.0 D. 34 The Add-On IOL The Add-On is a 3-piece foldable IOL. The optic diameter is 7.0 mm with a posterior concavity designed to ensure a distance of approximately 0.5 mm between the optics of the supplemental and capsular lenses. This also provides iris protection and reduces photic phenomena. It has an overall length of 14.0 mm with a 45-degree sulcus contact area for long-term stability. The optic is made of silicone elastomer with a UV absorber. The modified C-loop haptics have 0-degree angulation and are made in high molecular weight PMMA. There are 4 types: the ASPIRA 3P-sPB (monofocal; Fig. 2), in which sphere range varies in 0.50 D increments between 6.0 D and +6.0 D and in 1.0 D increments from 23.0 D to 7.0 D and +7.0 D to D; the DIFFRACTIVA DIFF-sPB (multifocal), with an addition of (equivalent to +3.0 D at the spectacle plane) and in which the sphere range varies in 0.50 D steps between 6.0 D and +6.0 D; the TORICA-sPB, in which the sphere range varies in 0.50 D steps between 6.0 D and +3.0 D and in 1.0 D steps between 30.0 D and 7.0 D and between +4.0 D and +6.0 D and the cylinder range varies in 1.0 D steps between +1.0 D and D; and lastly, the TORICADIFFsPB in which the sphere range varies in 0.50 D steps between 2.5 D and +1.0 D and the cylinder range varies in 0.50 D increments between +1.0 D and +4.0 D. 35 The 1st Add-On IOL The 1st Add-On is a 1-piece, foldable, hydrophilic acrylic IOL. Optic diameter is 6.0 mm and overall length is 13.0 mm. It has convex-concave shape to minimize capsular IOL touch, a square design to prevent iris capture, and 4 flex-haptics to allow it to sit in the sulcus. There are 3 types: AddOn refractive (A4SW00; Fig. 3), in which the sphere range varies from 10.0 D to Figure 1. The Rayner Sulcoflex IOL (reprinted with permission from Rayner Intraocular Lenses Limited). Figure 2. The ASPIRA-3P-sSB IOL (reprinted with permission from Kestrel Ophthalmics Ltd) Asia-Pacific Academy of Ophthalmology 361

5 Manzouri et al Asia-Pacific Journal of Ophthalmology Volume 6, Number 4, July/August D in 0.25 D steps; AddOn toric (6 different models), in which the sphere range varies in 0.25 D steps between 10.0 D and D and the cylinder range varies in 0.75 D steps between +1.5 D and +9.0 D and in 1.0 D steps between +9.0 D and D; and AddOn progressive (3 models), which has an addition of +3.0 D and in which the sphere range varies in 0.25 D steps between 3.0 D and +3.0 D and in 0.50 D steps between 0.50 D and D. 36 The Surgical Technique Depending on the application, 2 implantation strategies for these supplemental IOLs are possible. They can either be implanted in the sulcus at the same time as the capsular bag IOL in a single surgical procedure, or separately (into a pseudophakic eye) in a planned subsequent surgery. In all cases, the authors advise that a peripheral iridotomy/iridectomy should be considered. A 1-stage procedure is a sensible option when there is an expectation of changing refraction or when the IOL is likely to be replaced at a later date. Aphakia should be corrected with the capsular bag IOL and a supplementary lol can then be used to provide additional optical features (multifocality, toricity, etc.). In a 2-stage procedure, the insertion of the supplementary IOL can be performed at any time, even long after the preceding capsular bag IOL implantation. A 2-stage procedure may be indicated to optimize postoperative refractive results or for patients who want to take advantage of the benefits of a premium IOL (toric, multifocal, etc.) after cataract surgery. Surgery in all cases is performed through incisions used for standard cataract surgery. Preoperatively the pupils are dilated with eye drops (phenylephrine 10% and tropicamide 1%). A clear corneal incision is performed (1st Add-On IOL can be inserted through a 2.2-mm incision, Sulcoflex IOL through a 3.0-mm incision using the Rayner Single Use Soft-Tipped Injector, and the Add-On through a 3.2-mm incision). A cohesive viscoelastic is used, when needing to insert the supplementary lens, to enlarge the sulcus to facilitate IOL insertion. The viscoelastic must be completely removed at the end of the procedure, especially for toric IOLs. The secondary IOL is implanted with an injector (Sulcoflex and 1st Add-On) or with forceps (Add-On) into the sulcus. After implantation of the IOL, the viscoelastic device is aspirated, including between the IOLs. The wound is hydrated with balanced salt solution and intracameral cefuroxime is administered. 37 The implantation of a secondary IOL with the piggyback technique is fairly easy for an experienced anterior segment surgeon and is safer than explanting an IOL that was implanted many years beforehand. The explantation of an IOL, in which there is marked fibrosis of the capsular bag, may have serious implications, such as capsular rupture with vitreous loss, which can result in retinal tears/detachment or macular edema, zonular damage, and cyclodialysis, along with an increased difficulty in the implantation of an IOL with the correct power. The IOL power calculation of a secondary piggyback IOL is more predictable than that of an IOL exchange because it is calculated purely based on the patient s subjective refraction and so it is not necessary to know the power of the primary IOL. 6,38 The implantation of a secondary IOL is a reversible procedure, enables the correction of a wider range of refractive errors, and has stable long-term refractive results in comparison with laser ablation procedures. The Ideal Supplementary IOL Patient The ideal supplementary IOL candidate patient has a stable posterior capsular IOL that is completely within an intact capsular bag, a normal or deep anterior chamber, a normal corneal endothelium, and no evidence of pigment dispersion syndrome. Not every patient can tolerate a piggyback IOL. Contraindications include the preoperative presence of pigmentary dispersion syndrome, especially in the presence of glaucoma or elevated IOP. Patients who have loose zonules from trauma or pseudoexfoliation are also not good candidates for supplementary IOLs. Other contraindications include patients who required a capsular tension ring for primary lens implantation and the presence of posterior synechiae to the capsular bag. Patients with a significantly reduced corneal endothelial cell count are at risk for corneal endothelial cell decompensation with a piggyback lol, but patients with mild guttata can tolerate these lenses. 39 CONCLUSIONS This article has looked at the treasure trove of modern supplemental IOLs. Fundamentally different in design from IOLs designed for in-the-bag placement, they should clearly be differentiated from piggybacking, when IOLs designed for capsular fixation were placed in the sulcus with resulting optical and pressure problems. Therefore, we strongly advise the use of the term supplemental IOLs for modern designs. Similarly, the variety of different optics now available mean that simply referring to surgery as primary or secondary is obsolete, and a thoughtful new nomenclature based on the concept of duet procedures has been presented. Modern supplemental IOLs are new tools easily added to the repertoire of anterior segment surgeons. Their versatility means they can be used in a large variety of situations from pediatric cataract surgery to reversible presbyopia surgery. The authors predict that their use will become widespread in the near future. Figure 3. The 1stQ AddOn spherical IOL (A4SW00) (reprinted with permission from 1stQ Deutschland GmbH). 1. REFERENCES Sales CS, Manche EE. Managing residual refractive error after cataract surgery. J Cataract Refract Surg. 2015;41: Asia-Pacific Academy of Ophthalmology

6 Asia-Pacific Journal of Ophthalmology Volume 6, Number 4, July/August Eleftheriadis H, Sciscio A, Ismail A, et al. Primary polypseudophakia for cataract surgery in hypermetropic eyes: refractive results and long term stability of the implants within the capsular bag. Br J Ophthalmol. 2001;85: Kuo IC, O Brien TP, Broman AT, et al. Excimer laser surgery for correction of ametropia after cataract surgery. J Cataract Refract Surg. 2005;31: Ruckl T, Dexl AK, Bachernegg A, et al. Femtosecond laser-assisted intrastromal arcuate keratotomy to reduce corneal astigmatism. J Cataract Refract Surg. 2013;39: Jin GJ, Merkley KH, Crandall AS, et al. Laser in situ keratomileusis versus lens-based surgery for correcting residual refractive error after cataract surgery. J Cataract Refract Surg. 2008;34: Gayton JL, Sanders V, Van der Karr M, et al. Piggybacking intraocular implants to correct pseudophakic refractive error. Ophthalmology. 1999; 106: Hill WE. 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