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 Table of Contents  
REVIEW ARTICLE
Year : 2021  |  Volume : 9  |  Issue : 2  |  Page : 51-54

Intraocular lens opacification: A rare enigma


Department of Community Ophthalmology, Global Hospital Institute of Ophthalmology, Sirohi, Rajasthan, India

Date of Submission23-Jul-2020
Date of Decision10-Jan-2021
Date of Acceptance06-May-2021
Date of Web Publication31-Jul-2021

Correspondence Address:
Prateek Jain
Global Hospital Institute of Ophthalmology, Abu Road, Sirohi - 307 510, Rajasthan
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcor.jcor_115_20

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  Abstract 


Intraocular lens (IOL) opacification is an infrequent and often delayed complication of cataract surgery. However, correct diagnosis of the complication followed by appropriate management is crucial for effective treatment. In spite of exhaustive research, the authors were not able to find comprehensive literature comprising all facets of IOL opacification. This article hopes to address this deficiency. Detailed literature search on IOL opacification was carried out using PubMed Medline, Web of Science, and Google Scholar. The studies which adhered to the inclusion and exclusion criteria were considered for this article.

Keywords: Hydrophilic intraocular lens, hydrophobic intraocular lens, intraocular lens calcification, intraocular lens explantation, intraocular lens opacification


How to cite this article:
Jain P, Pattnaik A. Intraocular lens opacification: A rare enigma. J Clin Ophthalmol Res 2021;9:51-4

How to cite this URL:
Jain P, Pattnaik A. Intraocular lens opacification: A rare enigma. J Clin Ophthalmol Res [serial online] 2021 [cited 2022 Jul 2];9:51-4. Available from: https://www.jcor.in/text.asp?2021/9/2/51/322784



Although generally considered as a privileged site, the intraocular environment does not preclude opacification. Intraocular lens (IOL) opacification is a rare but irreversible complication of cataract surgery [Figure 1]. In fact it has been reported as the third most common cause for IOL explantation following IOL dislocation and incorrect IOL power.[1] Clinical observations of opacification of hydrogel IOLs were first reported in 1987.[2] The causes of opacification can vary from conditions associated with the patient, type of IOL, IOL manufacturer, IOL storage, cataract extraction techniques, and additional procedures if any.[3] The potential for IOL opacification must be considered when evaluating the long-term biocompatibility of lens material. The management consists of IOL explanation and re-implantation of a new IOL. The purpose of this review is to enable a better understanding of the causes, risk factors, and effects of IOL opacification and to help clinicians manage such cases appropriately.
Figure 1: Opacified intraocular lens on slit-lamp biomicroscopy as photographed by the author

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The incidence of IOL opacification varies from 1.1% to 14.5%[4] based on the presence of above-mentioned factors. Duration for IOLs to be opacified varies from as less as 1 year after the surgery[5] to 7 years or longer[6] IOL opacification has most often been observed unilaterally but on rare instances, it can also be bilateral.[7]

The patient often has reduced visual acuity with low contrast sensitivity in the affected eye.[8]


  Methodology Top


A review of the existing literature was carried out with search focused on the etiology, pathogenesis, structural and biochemical analysis as well as diagnosis and management of opacification of IOLs. The search was made using the following databases: PubMed Medline, Web of Science, and Google Scholar including keywords “IOL opacification,” “causes of IOL opacification,” “structure of opacified IOL,” and “management of opacified IOL.”

The search included studies published from 2000 to 2020. The inclusion criterion was that articles must be original articles, review articles and case reports/series of IOL opacification. Descriptive studies with sample populations including all ages were included. Studies where main objective was not to describe the lens opacification, nonoriginal articles, and studies in a language other than English were excluded. The search was carried out in April 2020. Review of the study by the local institutional ethics committee was exempted since the study did not involve human subjects directly.

Etiology

(DELETE): IOL opacification has been associated with diabetes mellitus and also been reported in patients having hypertension and renal insufficiency.[5]

The type of IOL implanted is a crucial determinant for future opacification. Different patterns of opacification are observed in different IOLs such as Snowflake opacification in polymethylmethacrylate IOLs, discoloration in silicone IOLs, opacification in hydrophilic acrylic IOLs, and microvacuoles (glistenings) in hydrophobic acrylic IOLs.[9],[10] IOL material, structure, and sleeves used to hold IOL and IOL packaging have an impact on the incidence of opacification.[11] Most severe cases of IOL opacification have been associated with hydrophilic or hydrophilic-hydrophobic IOLs, but rarely with hydrophobic IOL.[12] The opacification may be present in anterior and posterior surface, deep central region, haptics, or in the entire IOL.[6]

The type of intraocular surgery performed, the techniques used while performing different steps of the surgery, any additional procedures performed during or after the primary surgery and type of chemicals used in surgery such as viscoelastics significantly dictate the chances of opacification. For instance, it has been documented to occur after nondescemet stripping automated endothelial keratoplasty (n-DSAEK), DSAEK, intravitreal air injection after pars plana vitrectomy (PPV), combined phacovitrectomy or following use of intraocular gas in complicated traumatized eyes.[13],[14],[15] Hence, in patients with Fuchs endothelial dystrophy who might require descemet membrane endothelial keratoplasty or DSAEK surgery and in patients with vitreoretinal pathology who might require PPV, implantation of hydrophilic acrylic IOL is not recommended as there is increased risk of IOL opacification after such procedures.

The presence of asteroid hyalosis, breakdown of blood aqueous barrier intraoperatively, and excessive postoperative inflammation have also been implicated in the pathogenesis of IOL Opacification. Secondary surgical interventions with instillation of foreign material into the anterior chamber, such as air, gas, or recombinant tissue plasminogen activator increase the risk of IOL opacification. Creation of direct contact between the posterior IOL surface and the vitreous after neodymium-doped yttrium aluminum garnet (Nd: YAG) laser posterior capsulotomy predisposes to IOL opacification.[8],[16]

IOL opacification has been classified by Neuhann et al. as (i) primary opacification, (ii) secondary opacification, and (iii) pseudocalcification.

Primary form refers to calcification inherent in the IOL material, based on possible inadequate formula of the polymer, the fabrication of the IOL, or issues with the packaging process. The calcification presumably occurs in otherwise normal eyes and seems not to be associated with comorbidities.

The secondary form refers to secondary superficial calcium deposits on the IOL, most likely because of environmental circumstances with changes in the intraocular aqueous milieu. These might occur with preexisting or concurrent diseases with disruption of the blood-aqueous barrier in patients with diabetes, uveitis, or in those who had a fluid-gas exchange during vitreoretinal surgery. By definition, it is not related to any problem with the IOL itself.

The third form refers to pseudocalcification phenomena when another pathology is mistaken for calcification or false-positive staining for calcium occurs.[17]

Pathogenesis

Several studies have suggested that the reaction to an implanted IOL significantly depends on protein adsorption on IOL surface, especially in the presence of microdefects on the polymer surfaces where they can attach. After adsorption, tightly bound complexes of protein and calcium form and this process are promoted by long chain fatty acids. Such macromolecules contribute to the formation of calcification nuclei and further propagation of the process.[18],[19]

The origin of such calcified nuclei, especially in hydrophilic IOLs is suggested to be from the increased calcium, phosphate, and albumin levels in the aqueous humor which often results from a breakdown of blood aqueous barrier.[20]

Other possible mechanisms include excessive inflow of water in hydrophobic materials, direct discoloration caused by dyes or medications, and even slow and progressive degradation of the IOL material.[21]

Structural and biochemical analysis

Anterior segment–optical coherence tomography (OCT) showed the presence of hyperreflective materials in the anterior surface of IOL [Figure 2].[12]
Figure 2: Anterior segment-optical coherence tomography revealing the presence of hyperreflective materials in the anterior surface of intraocular lens (a) Anterior segment-optical coherence (AS-OCT) tomography revealing the presence of hyperreflective materials in the anterior surface of intraocular lens- complete cross sectional view. (b) Magnified view of AS-OCT.[14]

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Light microscopy revealed numerous confluent ovaloid or spherical deposits just underneath the anterior optical surface. The opacifications invariably stained positive with Alizarin Red for calcium. The von Kossa staining of cross sections of the IOLs revealed numerous fine granular crystalline deposits distributed in a line parallel to and immediately underneath the anterior optical surface of the IOL [Figure 3].[16]
Figure 3: Light microscopic evaluation of opacified intraocular lens. (a) surface opacification with clear areas in between. (b) Image of intraocular lens optic at higher magnification. (c) Uniformly opacified intraocular lens, with some clear areas at the edges (staining with alizarin red 1%). (d) Image of intraocular lens haptic at a higher magnification[5]

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Surface electron microscopy reveals numerous fine and roughly spherical crystalline deposits of approximate 2–15 μm in diameter situated underneath the optical surface of the IOL, with an intervening clear zone. It has also been reported to show plate-like as well as prismatic nanoparticle deposits of calcium phosphate crystallites on the surface and in the interior of opacified IOLs [Figure 4]. The plate-like deposits exhibited morphology and particle size typical for octacalcium phosphate (OCP), while the respective characteristics of the prismatic nanocrystals were typical of hydroxyapatite (HAP). In some cases, microvacuoles within the crystals causing microscopically small cracks through the optical surface were also observed.[16],[22],[23]
Figure 4: Multiple high magnification scanning electron microscope-scans from cross-sections through the anterior optical surface showing calcium deposits[16]

Click here to view


Element mapping and X-ray spectroscopy also showed the deposits to be made up of calcium phosphate and calcium apatite.[18],[23]

Aqueous humor analysis showed that the humor is supersaturated with respect to both OCP and HAP, favoring the formation of the thermodynamically more stable HAP, while the formation and kinetic stabilization of other transient phases is also very likely.[20]

Diagnosis and management

The patient complains of gradual, progressive loss of vision with a grayish brown tint. On examination, visual acuity is observed to be reduced with low contrast sensitivity in the eye with opacified IOL.[8]

Diagnosis of opacified IOL can be done easily during slit-lamp biomicroscopy without the need for any additional investigations. A milky white opalescence of the entire IOL resembling a cataract along with a normal anterior and posterior segment is observed.

It is vital to differentiate IOL opacification from posterior capsular opacification (PCO) where the posterior capsule undergoes secondary opacification due to the migration, proliferation, and differentiation of lens epithelial cells. Therapeutic procedures for PCO such as posterior capsulotomy with Nd: YAG laser make explantation of opacified IOL and implantation of a new IOL in the capsular bag more difficult, in addition to subjecting the patient to an unnecessary procedure which is not exempt from complications.

The definitive management is explantation of opacified IOL followed by implantation of a new IOL. Meticulous dissection of the IOL from the capsular bag is the key to successful explantation. Explantation may involve extraction of just optic leaving the haptic in situ or removal of the entire IOL. Secondary IOL can be placed in the capsular bag, ciliary sulcus, or anterior chamber in these patients. Scleral fixated IOL, sutured iris fixated IOL, and retro-pupillary iris claw IOL are also viable options. Intraoperative complications include rupture of the posterior capsule, zonular dehiscence, IOL drop, hyphema, iridodialysis, and corneal decompensation.[24],[25]


  Conclusion Top


IOL opacification is a rare but irreversible complication of cataract surgery. While the maximum incidence has been observed in hydrophilic IOLs, opacification can occur in any type of IOL. It primarily occurs due to dystrophic calcification on IOL surface as a result of interplay of multiple systemic and local risk factors. Management involves the extraction of opacified IOL and implantation of a new IOL.

Acknowledgment

The authors acknowledge the guidance of Dr. V C Bhatnagar, Head of Department and Medical Superintendent, Global Hospital Institute of Ophthalmology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Fernández-Buenaga R, Alió JL. Intraocular lens explantation after cataract surgery: Indications, results, and explantation techniques. Asia Pac J Ophthalmol (Phila) 2017;6:372-80.  Back to cited text no. 1
    
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Buchen SY, Cunanan CM, Gwon A, Weinschenk JI, Gruber L, Knight PM. Assessing intraocular lens calcification in an animal model. J Cataract Refract Surg 2001;27:1473-84.  Back to cited text no. 2
    
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Werner L. Opacification and degradation of the implanted intraocular lenses. In: Biomaterials and Regenerative Medicine in Ophthalmology. Cambridge: Elsevier; 2016. p. 419-42.  Back to cited text no. 3
    
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Balasubramaniam C, Goodfellow J, Price N, Kirkpatrick N. Opacification of the Hydroview H60M intraocular lens: Total patient recall. J Cataract Refract Surg 2006;32:944-8.  Back to cited text no. 4
    
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Gurabardhi M, Haaberle H, Aurich H, Werner L, Pham DT. Serial intraocular lens opacifications of different designs from the same manufacturer: Clinical and light microscopic results of 71 explant cases. J Cataract Refract Surg 2018;44:1326-32.  Back to cited text no. 5
    
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Fernández J, Sánchez-García A, Rodríguez-Vallejo M, Piñero DP. Systematic review of potential causes of intraocular lens opacification. Clin Exp Ophthalmol 2020;48:89-97.  Back to cited text no. 6
    
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Pandey SK, Werner L, Apple DJ, Kaskaloglu M. Hydrophilic acrylic intraocular lens optic and haptics opacification in a diabetic patient: Bilateral case report and clinicopathologic correlation. Ophthalmology 2002;109:2042-51.  Back to cited text no. 7
    
8.
Ronge LJ. Opacification of IOLs: A Problem Often Misdiagnosed? Eyenet Magazine; September 2005. Available from: https://www.aao.org/eyenet/article/opacification-of-iols-problem-often-misdiagnosed. [Last accessed on 2020 Jun 20].  Back to cited text no. 8
    
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Werner L. Glistenings and surface light scattering in intraocular lenses. J Cataract Refract Surg 2010;36:1398-420.  Back to cited text no. 9
    
10.
Apple DJ, Peng Q, Arthur SN, Werner L, Merritt JH, Vargas LG, et al. Snowflake degeneration of polymethyl methacrylate posterior chamber intraocular lens optic material: A newly described clinical condition caused by unexpected late opacification of polymethyl methacrylate. Ophthalmology 2002;109:1666-75.  Back to cited text no. 10
    
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Ghosh YK, Goodall KL. Total opacification of intraocular lens implant after uncomplicated cataract surgery: A case series. Arch Ophthalmol 2004;122:782-4.  Back to cited text no. 11
    
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Prasad PS, Oliver SC, Gonzales CR. Midlenticular optic opacification af a hydrophobic acrylic intraocular lens in association with retained perfluorocarbon liquid following vitreoretinal surgery. Ophthalmic Surg Lasers Imaging 2010;9:1-2.  Back to cited text no. 12
    
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Walker NJ, Saldanha MJ, Sharp JA, Porooshani H, McDonald BM, Ferguson DJ, et al. Calcification of hydrophilic acrylic intraocular lenses in combined phacovitrectomy surgery. J Cataract Refract Surg 2010;36:1427-31.  Back to cited text no. 13
    
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Ma ST, Yang CM, Hou YC. Postoperative intraocular lens opacification. Taiwan J Ophthalmol 2018;8:49-51.  Back to cited text no. 14
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Dhital A, Spalton DJ, Goyal S, Werner L. Calcification in hydrophilic intraocular lenses associated with injection of intraocular gas. Am J Ophthalmol 2012;153:1154-600.  Back to cited text no. 15
    
16.
Giers BC, Tandogan T, Auffarth GU, Choi CY, Auerbach FN, Sel S, et al. Hydrophilic intraocular lens opacification after posterior lamellar keratoplasty – A material analysis with special reference to optical quality assessment. BMC Ophthalmol 2017;17:150.  Back to cited text no. 16
    
17.
Neuhann IM, Kleinmann G, Apple DJ. A new classification of calcification of intraocular lenses. Ophthalmology 2008;115:73-9.  Back to cited text no. 17
    
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Amon M. Biocompatibility of intraocular lenses. J Cataract Refract Surg 2001;27:178-9.  Back to cited text no. 18
    
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Linnola RJ, Werner L, Pandey SK, Escobar-Gomez M, Znoiko SL, Apple DJ. Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 2: Explanted intraocular lenses. J Cataract Refract Surg 2000;26:1807-18.  Back to cited text no. 19
    
20.
Nakanome S, Watanabe H, Tanaka K, Tochikubo T. Calcification of Hydroview H60M intraocular lenses: Aqueous humor analysis and comparisons with other intraocular lens materials. J Cataract Refract Surg 2008;34:80-6.  Back to cited text no. 20
    
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Jorge PA. Intraocular lens opacification. Rev Bras Oftalmol 2014;73:69-70.  Back to cited text no. 21
    
22.
Gartaganis SP, Kanellopoulou DG, Mela EK, Panteli VS, Koutsoukos PG. Opacification of hydrophilic acrylic intraocular lens attributable to calcification: Investigation on mechanism. Am J Ophthalmol 2008;146:395-403.  Back to cited text no. 22
    
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Werner L. Causes of intraocular lens opacification or discoloration. J Cataract Refract Surg 2007;33:713-26.  Back to cited text no. 23
    
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Yu AK, Ng AS. Complications and clinical outcomes of intraocular lens exchange in patients with calcified hydrogel lenses. J Cataract Refract Surg 2002;28:1217-22.  Back to cited text no. 24
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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