Removal of “acrylic pearls” from acrylic lenses

correspondence Removal of “Acrylic Pearls” from Acrylic Lenses

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e would like to describe an observation that we encountered during implantation of acrylic foldable intraocular lenses (IOLs). Acrylic IOLs are becoming increasingly popular among IOL surgeons worldwide.1 In a survey of the practice styles and preferences of members of the American Society of Cataract and Refractive Surgery, Leaming found that over half the respondents preferred acrylic IOLs for implantation after phacoemulsification.2 Owing to the squared-edge design of the optic of the AcrySof威 IOL (Alcon Laboratories, Inc.), the incidence of posterior capsule opacification has been found to be lower.3 The optical quality and ease of implantation are additional qualities that make it widely accepted for implantation. However, acrylic IOLs have been associated with compression marks, cracks, and glistenings.4 – 6 After implanting acrylic IOLs (AcrySof, MA60BM) for the past 2 years, we recently encountered an unusual finding in 2 lenses. In the first case, after the IOL was implanted, a small gelatinous material was found to be adherent to the center of the optic in the visual axis (Figure 1). The material was successfully detached from the optic by using an irrigating cannula and subsequently removed with a McPherson forceps. While the material was being detached, resinous fibers attached to the IOL optic could be seen. In a second case, a small triangular piece of material was adherent to the optic close to the optic–haptic junction. An irrigating cannula was used to gently detach it from the IOL optic; it was then removed with a McPherson forceps. Both samples were analyzed by infrared spectroscopy, and the peaks obtained were characteristic of polyacrylate material (Figure 2). Postoperatively, there was no anterior chamber reaction in either eye. Slitlamp biomicroscopy did not reveal acrylic residue or depression at the site of the attachment to the IOL optic. The visual acuity was 20/20 in both cases. Neither patient reported glare discomfort. The genesis of these “acrylic pearls” is unknown. They possibly occur during the manufacturing or packing of the lenses or perhaps later. These acrylic pearls, if © 2002 ASCRS and ESCRS Published by Elsevier Science Inc.

present, should be identified and removed immediately as was done in our cases. The pearls are amenable to removal and if left behind may be visually debilitating, especially if they are present in the center, obscuring the visual axis as was seen in our first case. Further, caution is mandatory in these cases because the presence of these acrylic pearls can compromise the quality of vision. If removed incompletely, the pearls can cause severe glare and a decrease in contrast sensitivity. Furthermore, even their complete removal can cause imperfection in the optical surface in the form of a facet, depression, or the impression of the tip of the instrument used to remove it, which may be responsible for suboptimal vision. Therefore, we recommend that care be taken to prevent

Figure 1. (Sinha) Acrylic pearl on the optic IOL.

Figure 2. (Sinha) Infrared spectroscopy reveals the presence of polyacrylate.

CORRESPONDENCE

such imperfections in the optic of the acrylic IOL to provide optimal quality of vision to the patient. RAJESH SINHA, MD JEEWAN S. TITIYAL, MD NAMRATA SHARMA, MD VANATHI M, MD RASIK B. VAJPAYEE, MBBS, MS New Delhi, India

References 1. Oshika T, Amano S, Araie M, et al. Current trends in cataract and refractive surgery in Japan—1999 survey. Jpn J Ophthalmol 2001; 45:383–387 2. Leaming DV. Practice styles and preferences of ASCRS members—2000 survey. J Cataract Refract Surg 2001; 7:948 –955 3. Nishi O, Nishi K. Preventing posterior capsule opacification by creating a discontinuous sharp bend in the capsule. J Cataract Refract Surg 1999; 25:521–526 4. Vrabec MP, Syverud JC, Burgess CJ. Forceps induced scratching of a foldable acrylic intraocular lens. Arch Ophthalmol 1996; 114:777 5. Pfister DR. Stress fractures after folding an acrylic intraocular lens. Am J Ophthalmol 1996; 121:572–574 6. Omar O, Pirayesh A, Mamalis N, Olson RJ. In vitro analysis of Acrysof intraocular lens glistenings in AcryPak and Wagon Wheel packaging. J Cataract Refract Surg 1998; 24:107–113

Use of the AMO SI-40NB Unfolder with the SI-55NB IOL in Highly Hyperopic Eyes

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he advantages of an injector system for intraocular lens (IOL) implantation with foldable IOLs are well known. The smaller wound size required as well as the narrow angle in axial hyperopic eyes make the use of an injection system potentially more advantageous than forceps insertion.1 However, the current AMO Unfolder system for the SI-55NB IOL (5.5 mm optic) is approved for IOLs up to 27.0 diopters (D). Initial studies with the SI-55NB IOL Unfolder system and the SI-5NB IOL higher than 27.0 D in power revealed optic and/or haptic damage with this insertion technique. Over this range, therefore, the manufacturer recommends a forceps insertion technique. I present a case and discuss my results using the AMO SI-40NB Unfolder system (designed for the SI-40NB IOL, which has a 6.0 mm optic and has a larger caliber Unfolder) with the

AMO SI-55NB IOL (5.5 mm optic IOL) in high dioptric powers. A 73-year-old woman developed visually significant cataracts and requested surgical intervention. The preoperative spherical equivalent was approximately ⫹6.00 D, and the axial length was 20.50 mm. The patient calculated for emmetropia at a power of 30.0 D with the AMO SI-55NB IOL. The patient had routine topical, temporal, clear corneal cataract extraction using a 2.65 mm diamond keratome. The viscoelastic agent was hyaluronate 3.0% (Vitrax威). A 30.0 D AMO SI-55NB IOL was placed in the AMO SI-40NB Unfolder after Vitrax was placed in the inserter. The insertion technique, chamber dwell time, and barrel dwell time were within the manufacturer’s recommendations.2 The IOL was inserted without difficulty. No cartridge cracks were noted after insertion.3 Nine other cases have been performed using between 28.0 and 30.0 D AMO SI-55NB IOLs with the AMO SI-40NB Unfolder with similar results. No IOL had haptic deformity, optic damage, or postoperative complications related to the insertion technique. The cross-sectional area of an IOL is commonly measured when analyzing injector system compatibility. The cross-sectional area of a 30.0 D AMO SI-55NB IOL is approximately 5% smaller than that of a 19.0 D AMO SI-40NB IOL (R. Glick, Allergan, written communication, February 2001). Although the 30.0 D IOL has a greater central thickness, the cross-sectional area is smaller because of the 5.5 mm optic and thinner edge design. (The AMO SI-40NB IOL has a 6.0 mm optic.) The actual diameter of the refractive portion of the 2 IOLs (SI-40NB and SI-55NB) in these high dioptric powers is the same, 5.0 mm. Using the Unfolder lens injection system for the AMO SI-40NB IOL with the AMO SI-55NB IOL appears to be a safe alternative in patients who require an IOL power between 28.0 and 30.0 D. A dispersive viscoelastic agent (Vitrax) was used in this series of patients. Previous studies have shown that dispersive viscoelastic agents have a lower torque value and lower adverse event rates overall with the Unfolder injection system than other viscoelastic agents.4 I routinely use the SI-55NB IOL (5.5 mm optic) in highly hyperopic eyes with a small anterior segment. The compression force necessary to implant the SI-55NB IOL is less than that to implant the SI-40NB IOL, and the effective re-

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