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Hydrogel Intraocular Lens Opacification and Calcification Pathology using a MemoryLens Model

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Title: Hydrogel Intraocular Lens Opacification and Calcification Pathology using a MemoryLens Model

Author(s): Jed H Assam, M.S., and Nick Mamalis, MD

Photographer: Jed H Assam

Date: 7/13/2016

Location in Core: Lens and Cataract > Complications of Cataract Surgery > Complications of IOL Implantation

Keywords / Main Subjects: IOL Calcification, IOL Opacification, MemoryLens, Hydrogels, Hydrophilic Acrylic

Diagnosis / Differential Diagnosis: Posterior Capsular Opacity, Soemmering’s Ring, Anterior Capsule Contraction Syndrome (ACCS)/Capsular Phimosis, Anterior Vitreous Floaters

Figure 1. The anterior surface of an explanted 3-piece hydrophilic acrylic IOL (MemoryLens) with significant calcification shown using light microscopic (large) and stereotactic (small) imaging.


Intraocular lens (IOL) opacification and calcification represent uncommon, but noteworthy causes of blurry vision and decreased visual acuity in pseudophakic patients. Awareness of this pathology becomes particularly important when considering the consequences of reflexively performing initial, errant procedures (nd:YAG and vitrectomy) directed at more common anatomic sources of visual disturbance in pseudophakic populations that typically includes the capsular bag or hyaloid.1,3 A survey (n = 142) evaluating foldable IOL complications requiring removal or secondary interventions identified IOL opacification as a minor cause of postoperative complication in most lens categories evaluated.6 However, for hydrogel (hydrophilic acrylic) IOLs, which represented 4% of the IOLs used in the study, post-operative opacification/calcification was the most common reason for lens removal.6

An explanted, calcified, posterior chamber IOL, MemoryLens (Ciba Vision Corp., Duluth, GA, USA), has been demonstrated in Figure 1. The MemoryLens is a 3-piece foldable hydrogel that was initially released in 1994.3,4 It has been the most heavily documented IOL with postoperative calcification complications in the United States.6 Several other hydrophilic acrylic lenses have also been implicated in calcific opacification as well (Hydroview, Bausch & Lomb; AquaSense, Ophthalmic Innovations International; SC60B-OUV, Medical Development Research).4,7


The time required from initial lens placement to the development of visually significant opacification in hydrogel lenses can take several years.1,7 The mean interval for the MemoryLens IOL was identified by one study examining 106 explanted lenses to be 25.8 ±11.9 months with a range from approximately 3 months to 6 ½ years.1

MemoryLens predisposition to opacification was believed to be related to the buffering process of the lenses manufactured through the year 1999.1,3,4 The mechanism by which granular calcific opacification (Figure 2) occurs in vivo remains unknown.  It is presently believed to be a multifactorial event related to the surface ionization of hydrogel under physiologic pH levels which facilitate calcium precipitation.4,7

Figure 2. High magnification light microscope image demonstrating Alizeran red staining on half of the calcified MemoryLens optic surface compared to an unstained half with granular deposits of calcium.

Risk Factors/Symptoms:

Some of the risk factors that have been associated with hydrogel IOL calcifications include exposure to surgically introduced exogenous substances such as gas, air, tissue plasminogen activator, and silicone oil.  Other risk factors include contact with lens packaging materials and lens polishing techniques.1,8 It is currently unknown whether the direct contact of surgical exogenous substances to the optical surface facilitates calcium precipitation or if such sequela is a consequence of increased inflammation resulting from surgical manipulation.7  Progressive visual loss is the most common primary symptom complaint identified in patients with calcified IOLs.6,7


Diagnostically, the presence of calcium may be confirmed on pathologic analysis post-explantation by observing characteristic histochemical staining of granules with Alizeran (1,2-dihydroxyanthraquinone) red, as shown in Figure 2 and Figure 3c, and by electron microscopy coupled with energy dispersive x-ray spectroscopy.8 Diffuse granular deposition is typically noted over the lens body, but tends to be more heavily concentrated on the optic center. In the MemoryLens the coated anterior surface shows heavier calcification than the posterior surface which shows less. Early on the posterior surface typically remains free of deposits (Figure 2b and d).3,4 For hydrogel lenses in general, calcium deposition distribution may be superficial, intralenticular, or both.7

Figure 3. Stereotactic images of a calcified MemoryLens following explantation. Lens opacification from anterior views can be appreciated on both unstained (a) and stained (c) lenses with significant granular calcium deposits. A relatively smooth posterior lens surface without deposition is appreciated on views of unstained (b) and stained (d) lens surfaces.


The only treatment currently available for resolving situations of an opacified calcific IOL includes explantation.5


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  2. Werner L. Biocompatability of intraocular lens materials. Current Opinion in Ophthalmology. 2008;19:41-49
  3. Haymore J, Zaidman G, Werner L, Mamalis N, Hamilton S, Cook J, Gillette T. Misdiagnosis of hydrophilic acrylic intraocular lens optic opacification: Report of 8 cases with the MemoryLens. Ophthalmology. 2007;114(9):1689-1695
  4. Neuhann IM, Werner L, Izak AM, Pandey SK, Kleinmann G, Mamalis N, Neuhann TF, Apple DJ. Late postoperative opacification of a hydrophilic acrylic (hydrogel) intraocular lens. Ophthalmology. 2004;111:2094-2101
  5. Werner L. Calcification of hydrophilic acrylic intraocular lenses. Am J. Ophthalmol. 2008;146(3):341-343
  6. Mamalis N, Brubaker J, Davis D, Espandar L, Werner L. Complications of foldable intraocular lenses requiring explantation or secondary intervention—2007 survey update. J Cataract Refract Surg. 2008;34:1584-1591
  7. Gartaganis SP, Prahs P, Lazari ED, Gartaganis PS, Helbig H, Koutsoukos PG. Calcification of hydrophilic acrylic intraocular lenses with a hydrophobic surface: laboratory analysis of 6 cases. Am J Ophthalmol. 2016;168:68-77
  8. Werner L, Wilbanks G, Ollerton A, Michelson J. Localized calcification of hydrophilic acrylic intraocular lenses in association with intracameral injection of gas. J Cataract Refract Surg. 2012;38:720-721