DEC 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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22 December 2013 EW CATARACT Cataract/IOL complications: Moran CPC reports A case of late postoperative opacification of a silicone IOL by Caleb Morris, MD, Liliana Werner, MD, PhD, and Nick Mamalis, MD served. The deposits on the posterior optic surface stained positive for calcium (alizarin red stain). Comments Caleb Morris, MD W Nick Mamalis, MD e have analyzed explanted silicone IOLs from almost 30 cases similar to the case described here in our laboratory. Although still relatively rarely described, surgeons should be aware of the possibility of this complication. Case report A 68-year-old woman presented with decreased vision in both eyes in 1999. At that time her best corrected visual acuity (BCVA) was 20/50 OU. On further examination she was found to have 2+ nuclear sclerotic cataracts bilaterally. Asteroid hyalosis was noted in her right eye. The patient had no history of diabetes mellitus. Shortly thereafter she underwent uncomplicated cataract surgery with implantation of an AMO (Santa Ana, Calif.) SI-30 threepiece silicone IOL in the right eye and a STAAR (Monrovia, Calif.) AQ2003V three-piece silicone IOL in the left eye. In 2008, 9 years later, she returned with complaints of decreased vision and was found to have BCVA of 20/40 OD, 20/30 OS with bilateral posterior capsule opacification, which was worse in the right eye. Liliana Werner, MD, PhD In May 2008 she underwent Nd:YAG laser posterior capsulotomies with the right eye done one week prior to the left eye. At that time no unusual posterior capsule opacification or deposits were noted in either eye after laser treatment. In February 2009, nine months later, the patient returned with complaints of decreased vision and was found to have a BCVA of 20/50 in her right eye. Posterior optic deposits were seen on slit lamp examination. Subsequently Nd:YAG laser "dusting" of the posterior optic surface was performed and BCVA improved to 20/25. Six months later, more deposits were seen on the posterior optic surface, and were associated with decreased visual acuity. The lens was therefore explanted. Laboratorial analyses & results The explanted IOL was sent to our laboratory in the dry state. Gross analysis was performed revealing whitish deposition on the posterior optic surface, concentrated in the central optic zone of the lens with irregular eccentric clearing. Light microscopy demonstrated that the deposits appeared confluent and crust-like in some areas; Nd:YAG laser optic pits could also be ob- Clinical photographs taken before (left) and after (right) Nd:YAG laser application to clean the posterior optic surface of the lens Source: Jason Jones, MD, Sioux City, Iowa Asteroid hyalosis is characterized by brilliant reflecting particles (asteroid bodies) floating in an apparently normal vitreous body. It usually appears unilaterally without any recognizable predisposition to gender or race.1 An electron spectroscopic imaging study conducted by Winkler and Lunsdorf confirmed a homogenous distribution of calcium, phosphorus, and oxygen within the asteroid bodies.2 The cases of silicone IOL calcification analyzed in our laboratory shared some common clinical characteristics.3-6 Many of the lenses were explanted because of decrease in visual acuity associated with the presence of whitish deposits on the posterior optic surface. Nd:YAG laser posterior capsulotomy was mostly performed years after IOL implantation, generally because of a diagnosis of decrease in visual acuity due to posterior capsule opacification. During the same laser session, the deposits on the posterior optic surface were observed, and could be partially removed or "dusted" from it. In other cases (such as the case described here), the deposits were first observed some months after Nd:YAG laser posterior capsulotomy. In any event, there was always a gradual increase in the density of the deposits after the capsulotomy procedure, mainly within the capsulotomy opening on the posterior surface of the lens. The phenomenon was originally described with plate silicone lenses, made of earlier generation silicone material.4 However, in a study from our laboratory, Stringham et al. reported a series of 22 cases of silicone IOL calcification related to 8 different designs including newer generation silicone IOLs.6 86.4% of cases had confirmed asteroid hyalosis, but in the remaining cases this information was sometimes not present in the patient chart (therefore the presence of asteroid hyalosis could not be completely ruled out). A previous case report by our center of a patient with bilateral asteroid hyalosis showed calcification of a three-piece silicone IOL but no calcification of the replacement PMMA IOL or of the contralateral hydrophobic acrylic AcrySof IOL (Alcon, Fort Worth, Texas).5 Studies on the barrier function of the posterior capsule demonstrated that it serves as a barrier only to large nonelectrolytes or negative electrolytes (e.g., lipids, proteins, hyaluronic acid, enzymes).7 Therefore, it is not surprising that calcium and phosphate originated from the vitreous in eyes with asteroid hyalosis may cross the posterior capsule and precipitate on the posterior IOL surface, even in the absence of posterior capsulotomies. Nd:YAG laser capsulotomy, however, promotes direct contact between the posterior IOL surface and the vitreous, possibly leading to acceleration of calcium precipitation. Dystrophic calcification of silicone lenses in the absence of asteroid hyalosis has not been reported. Indeed, in the absence of this vitreous condition, long-term calcified deposits previously were observed only on the surface or within the substance of some hydrophilic acrylic IOL designs.3 There is, therefore, increasing evidence that the material opacifying the silicone lenses is derived from the asteroid bodies or derived from a similar process that results in this vitreous condition. It is, however, still unclear why when compared to the assumed high volume of silicone lens implantation in patients with asteroid hyalosis only a few cases of calcification have been observed. Careful clinical examination of pseudophakic patients with asteroid hyalosis will confirm if this phenomenon is more widespread but only significant enough to require IOL explantation in a few cases. This will also confirm if the phenomenon is restricted to silicone lenses. Without such knowledge, it is difficult to proscribe silicone IOL implantation in the presence of asteroid hyalosis. Differential diagnosis 1. Calcification of an IOL is most commonly seen in hydrophilic acrylic IOLs and can be seen anywhere in the lens (surface/subsurface and/or substance of the lens). The calcified deposits cannot be removed from the surface of hydrophilic acrylic lenses by Nd:YAG laser. 2. Posterior capsule opacification is caused by migration and proliferation of residual lens epithelial

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