The following reader-author exchange refers to the article “Myth: Hydrophilic Acrylic IOLs Are Prone to Calcification and Should Be Avoided” by Abinaya Thenappan, MD; Shamik Bafna, MD; Harrison Sciulli, MD; and Llewelyn Rao, MD, which appeared as part of the cover series for CRST’s October 2024 edition.

The article aims to dispel the "myth” of hydrophilic IOL calcification. We read it with interest and concern, given that we, as a group of surgeons, are often asked to remove these IOLs after they calcify and cause significant vision loss. This is, unfortunately, a relatively common indication for IOL exchange in our practices, as we have previously reported (Figures 1–3).^1,2

In many cases, there has been no secondary procedure other than Nd:YAG laser capsulotomy. Unfortunately, this is often performed because calcification can be mistaken for posterior capsular opacification, which is already more frequent with hydrophilic acrylic lenses.³ When the Nd:YAG laser is used, it can pit the optic, further reducing clarity and complicating any subsequent IOL exchange.

The time frame for calcification typically ranges from about 7 to 15 years, but in cases where there has been a secondary surgical procedure (particularly when air or gas is placed in the eye, as in Descemet membrane endothelial keratoplasty or Descemet stripping automated endothelial keratoplasty [DSAEK]), opacification may occur much sooner. We have observed calcification as early as 3 months after scleral fixation of an Akreos implant (Bausch + Lomb), necessitating removal and replacement using the Yamane technique⁴ for intrascleral haptic fixation (ISHF) combined with pars plana vitrectomy (PPV) and DSAEK. More often, opacification is delayed and occurs years after the secondary surgery. Any secondary surgical procedure—including PPV, trabeculectomy, or intravitreal anti-VEGF injections—appears to increase the likelihood of this complication.

In their article, Dr. Thenappan and colleagues state that newer hydrophilic IOLs have an “anti-calcification coating” that reduces the risk, but no data are provided. We are not aware of any proven coating that effectively reduces this risk. Virtually every hydrophilic IOL on the market has demonstrated the capacity to calcify, with case reports involving a variety of lenses.^5-9 We have personally removed opacified Bausch + Lomb, Lenstec, Oculentis, Rayner, Morcher, and Carl Zeiss Meditec hydrophilic acrylic IOLs.^1,2 Most such cases are not reported and therefore never enter any database. There are also reports of Akreos lenses that calcified after scleral fixation without a secondary surgery.¹⁰

Removing a scleral-fixated Akreos lens is challenging and invasive. We implore surgeons not to use this lens for scleral fixation because alternative techniques are available that do not carry the risk of this complication. Although we believe that any hydrophilic acrylic implant poses a risk of calcification, some surgeons who are regarded as experts continue to place scleral-fixated hydrophilic lenses and recommend this practice. This risk can be avoided entirely with other options currently available (eg, Yamane ISHF, glued ISHF, scleral fixation) that use hydrophobic acrylic or PMMA lenses that do not carry a known risk of calcification.

As a group, we understand that hydrophilic acrylic lens material offers some optical benefits (eg, a low refractive index and high Abbe number). However, calcification is not a myth; it is a serious potential complication, particularly in complex eyes that may require future procedures. Calcification of hydrophilic lenses may be one of the leading causes of material-based pseudophakic vision loss worldwide⁶ and has driven the development of more sophisticated and successful IOL explantation techniques.^1,2 We believe that all cataract surgeons should carefully evaluate patients for corneal guttata and other pathology that might require secondary procedures, increasing the risk of calcification, before placing a hydrophilic acrylic lens. Given the wide range of hydrophobic acrylic options available, one should question the rationale for using a hydrophilic acrylic lens at all. We also believe that sutured scleral fixation of Akreos hydrophilic acrylic lenses in the absence of capsular support should be abandoned.>

—Steven G. Safran, MD; Dean P. Ouano, MD; Mark S. Gorovoy, MD;
Sadeer B. Hannush, MD; Audrey Rostov, MD; and Minas Coroneo,
BSc(Med), MBBS, MSc, MD, MS, FRACS, FRANZCO

1. Darian-Smith E, Safran SG, Öhman D, Coroneo MT. Choice and implications of intraocular lens in retinal surgery. In: Ohji M, Wong D, Chang A, eds. Macular Surgery: Current Trends and Controversies. Springer; 2020:533-547.

2. Safran SG, Darian-Smith E, Coroneo MT. Intraocular lens explantation following cataract surgery: indications, techniques, and video demonstrations. Eur J Ophthalmol. 2022;32(3):1333-1339.

3. Wu Q, Li Y, Wu L, Wang CY. Hydrophobic versus hydrophilic acrylic intraocular lens on posterior capsule opacification: a meta-analysis. Int J Ophthalmol. 2022;15(6):997-1004.

4. Yamane S, Sato S, Maruyama-Inoue M, Kadonosono K. Flanged intrascleral intraocular lens fixation with double-needle technique. Ophthalmology. 2017;124(8):1136-1142.

5. Dhital A, Spalton DJ, Goyal S, Werner L. Calcification in hydrophilic intraocular lenses associated with injection of intraocular gas. Am J Ophthalmol. 2012;153(6):1154-1160.

6. Neuhann IM, Neuhann TF, Rohrbach JM. Intraocular lens calcification after keratoplasty. Cornea. 2013;32(4):e6-e10.

7. Yildirim TM, Auffarth GU, Łabuz G, Bopp S, Son HS, Khoramnia R. Material analysis and optical quality assessment of opacified hydrophilic acrylic intraocular lenses after pars plana vitrectomy. Am J Ophthalmol. 2018;193:10-19.

8. Neuhann T, Yildirim TM, Son HS, Merz PR, Khoramnia R, Auffarth GU. Reasons for explantation, demographics, and material analysis of 200 intraocular lens explants [published correction appears in J Cataract Refract Surg. 2020;46(7):1068.]. J Cataract Refract Surg. 2020;46(1):20-26.

9. Renschler A, Kelkar N, Eid K, et al. Complications of foldable intraocular lenses requiring explantation or secondary intervention: 2022 survey with update of long-term trends. J Cataract Refract Surg. 2024;50(4):394-400.

10. Ahmed H, Subramanian S, Chalam KV. Opacification of a scleral-sutured Akreos AO60 intraocular lens in the absence of concurrent or subsequent surgery: a case series. J Surg Case Rep. 2023;2023(4):rjad181.

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Drs. Thenappan, Bafna, and Rao respond.

We would like to thank Dr. Safran and his colleagues for their thoughtful response regarding the potential for calcification in hydrophilic acrylic IOLs. We appreciate their extensive clinical experience and share their caution about using hydrophilic acrylic IOLs in eyes that may require subsequent surgery involving intraocular gas or air. In such cases, we prefer to use an alternative IOL. Our use of hydrophilic IOLs is limited to routine cataract surgeries where there is no anticipated need for future interventions requiring a gas bubble, such as in cases of clinically significant Fuchs dystrophy or retinal pathology.

Within this context, in our center, between three surgeons, we have implanted over 20,000 hydrophilic acrylic Rayner IOLs since 2016 without encountering a single instance of calcification. Furthermore, none of the 60 IOL exchanges or removals performed at our surgery center during that time were related to calcification of a hydrophilic acrylic IOL.

This clinical experience aligns with broader evidence. We queried two surgeons from different practices across the country with a combined experience of 65,000 cases (Bausch + Lomb and Lenstec hydrophilic lenses) over 15 years. Among their cases, only one instance of calcification was identified—in an eye with Fuchs dystrophy that underwent DSAEK (oral and email communications, November 2024). Similarly, a large study of 42,545 IOL implantations across various lens types (66% hydrophilic and 27.9% hydrophobic) reported an overall opacification rate of 0.03%, with 0.6% of hydrophilic lenses affected.¹ Finally, Rayner, a hydrophilic lens manufacturer, reported a calcification rate of only 0.0025% between 2016 and 2023, during which approximately 6.5 million Rayner lenses were implanted (Rayner, written communication, January 9, 2024).

Although calcification is exceedingly rare based on our collective clinical experience, the published literature, and industry reports, we acknowledge the occurrence has been described and is often cited in complex cases.^2-8 This highlights an important distinction: rather than dismiss hydrophilic lenses entirely, our article advocates for a more nuanced view that hydrophilic lenses can be safely used in routine cases.

WHAT IS THE BEST WAY TO EVALUATE AN IOL?

Evaluating IOLs based on a single complication, such as calcification, may not give the full picture. A more comprehensive metric for assessing IOL performance may be the overall reoperation rate, which accounts for all complications, including explantation for issues like dysphotopsia or unsatisfactory vision. For example, multifocal lenses are sometimes explanted for dysphotopsias, but we would not rule out using a multifocal IOL in appropriate candidates who understand the potential risks. While silicone IOLs have been associated with a higher risk of calcification in eyes with asteroid hyalosis,⁹ we still use silicone lenses when they are deemed the best option for a given case. Similarly, while calcification remains a potential risk for hydrophilic lenses, we believe they have valuable optical qualities that make them suitable for many patients in the appropriate context.

A broader analysis of IOL explantation cases helps contextualize the relative frequency of calcification compared to other causes of lens explantation. A survey of IOL complications requiring secondary intervention from 2007 to 2022 found that dislocation or decentration was the most common reason for explantation across all lens types.¹⁰ Multifocal IOLs were frequently linked to glare and optical aberrations. Calcification was reported but was considered a rare complication in hydrophilic acrylic and silicone lenses.¹⁰ Another study of 57 IOL exchanges found that the most common reasons for explantation were IOL dislocation (46%), incorrect IOL power (23%), and patient dissatisfaction (21%).¹¹ Surface calcification was seen in 7% of cases, including silicone lenses and the MemoryLens hydrophilic lens (Ciba Vision; no longer available). A separate study reviewing 105 IOL explantations found that subluxation or dislocation was the leading reason for removal (55.2%), followed by optical issues or incorrect IOL power (21%) and calcification (7.6%).¹² These studies highlight that calcification, while a concern, is a relatively uncommon cause of explantation compared to other complications.

TECHNOLOGICAL ADVANCES: PRIMARY VERSUS SECONDARY CALCIFICATION

The calcification of hydrophilic acrylic IOLs has been classified into primary and secondary types. Primary calcification is linked to manufacturing or packaging issues,¹³ whereas secondary calcification is believed to arise from external factors such as ocular inflammation, comorbidities, or secondary surgery.^2-8 In the 2000s, reports of primary calcification involving the Hydroview (Bausch + Lomb), MemoryLens, and Aqua-Sense (Ophthalmic Innovations International)¹⁴ prompted manufacturers to withdraw affected lenses from the market and change their manufacturing and packaging methods. Additionally, hydrophobic lens coatings were introduced to reduce calcification risk,¹⁵ as seen with the AT LISA tri (model 839MP, Carl Zeiss Meditec), which has been available in the European Union and Canada for over a decade but not in the United States. While primary calcification was more prevalent in older IOLs due to manufacturing defects, it has become a less significant concern with modern-day lenses due to improvements in production and storage processes. Secondary calcification remains a potential risk, particularly in cases that require the use of intraocular gases.

We reached out to Rayner regarding the incidence of calcification in their modern lenses. Between January 2016 and December 2023, Rayner reported an overall incidence rate of 0% for primary calcification and 0.0025% for secondary calcification in their hydrophilic lenses. While it is reasonable to assume that these figures may be underestimates, given that not all explanted lenses are returned to the manufacturer for analysis, the ballpark figure remains remarkably low. Additionally, it is worth noting that any lens returned to the company is subject to mandatory reporting.

NO PERFECT IOL: THE NEED FOR TAILORED CHOICES

There are no perfect IOLs, and there is no one-size-fits-all solution. At our center, in a given week, individual surgeons may use up to 10 different IOLs, ranging from hydrophilic acrylic monofocal lenses, hydrophobic acrylic monofocals (both aspheric and neutral), three-piece monofocals, monofocal plus, and extended depth of focus lenses to trifocals from two different manufacturers and light-adjustable silicone IOLs (Light Adjustable Lens, RxSight) . This variety reflects the fact that no single IOL is ideal for every patient. We tailor our choice of IOL based on the specific clinical context, including the patient’s ocular health and lifestyle needs and any potential risks associated with each IOL. Understanding the advantages and limitations of each type of IOL allows us to make the best decisions for our patients, ensuring that we match the right lens to the right patient.

Historical Perspective

The decision to use any IOL is rooted in a risk-benefit analysis. For example, the transition from PMMA lenses to foldable IOLs was accompanied by an increased rate of endophthalmitis,¹⁶ likely due to a shift from scleral tunnel incisions to clear corneal incisions. The benefits of convenience and ease of use justified this trade-off for most surgeons. Similarly, the use of polypropylene haptics introduced risks of decentration, while the widely used one-piece Alcon platform carries a risk of glistenings.¹⁷ These examples highlight how, as a field, we continually weigh the risks and benefits of new technologies to optimize patient outcomes.

Limitations of Hydrophobic IOLs: A Different Set of Challenges

It is worth noting that hydrophobic acrylic IOLs are not immune to complications. While rare, there have been reports of calcification in these lenses, too.¹⁸ On a broader scale, numerous studies have documented the association between hydrophobic acrylic IOLs and glistenings (Figure 1).^17,19-22 One study examining AcrySof IOLs (Alcon) found that glistenings were present in 86.5% of the eyes examined.²² Another study that randomly assigned 273 patients to one of seven types of IOLs observed glistenings in all groups and 40% to 67.5% of patients.²¹ Even Clareon IOLs (Alcon) have been reported to have a 5% incidence of glistenings.¹⁹ Although glistenings may not commonly result in IOL explantation, they can contribute to decreased BCVA and reduced contrast sensitivity. These imperfections highlight the importance of understanding the nuances of each lens type and factoring these into the clinical decision-making process.

Complex Cases

While hydrophilic lenses have specific optical advantages, their use in complex cases warrants caution. As mentioned earlier, in our experience with over 20,000 eyes, we consciously avoided using these lenses in scenarios where exposure to air bubbles, silicone oil, or intraocular gas was likely, such as in eyes with Fuchs or compromised retinal conditions. This decision was informed by the known risk of calcification in such contexts,^2-8 which remains a valid concern.

There is variability in the reported incidence of this complication. Nieuwendaal et al found that calcification occurred in 5% of eyes after Descemet stripping endothelial keratoplasty (8/160 eyes).²³ A recent study evaluating Akreos AO60 lenses in 783 eyes that underwent PPV found that only three eyes (0.38%) developed opacification.²⁴ A study evaluating 31 patients undergoing PPV and IOL implantation found that none of the Akreos lenses (n = 24 eyes) had developed calcification at 53 months, even those in patients with multiple comorbidities.²⁵ The study also found that both four-point sutured scleral fixation (Akreos AO60) and two-point sutureless flanged intrascleral fixation (CT Lucia, Carl Zeiss Meditec) provided good visual and refractive outcomes. Regardless of the incidence, these data indicate that calcification is a rare but real complication that cannot be ignored, particularly in eyes at higher risk.

Importantly, alternative techniques and lenses are not without challenges. The Yamane ISHF method carries risks of lens tilt, decentration, and uveitis-glaucoma-hyphema syndrome.²⁶ The CZ70BD lens (Alcon) requires a 7-mm incision and has single-point fixation, which increases the risk of lens tilt. The MX60 (Bausch + Lomb) can be sutured but with narrower dual-eyelet fixation compared to the wide four-point fixation of the Akreos (Figure 2). Additionally, it is a technically challenging lens to use—improper tension in the suture can lead to haptic breakage, and the lens itself can tilt or flip, resulting in uveitis-glaucoma-hyphema syndrome. In fact, in our practice, we have seen more reoperations from broken haptics with the MX60 than from calcified Akreos lenses. A retrospective study of 25 scleral-sutured MX60 IOL displacements found that eyelet fractures occurred postoperatively in 20 lenses (seven dislocated and 13 subluxated) and intraoperatively in five lenses.²⁷ There is no single perfect IOL or technique in these complex cases.²⁸

Ultimately, while hydrophilic lenses may be an option in certain cases, their use in complex eyes carries inherent risks that must be carefully weighed against the potential benefits and the known challenges of alternative techniques. In eyes with normal corneas and retinas, such as a dislocated lens in a pseudoexfoliation eye with a healthy endothelium, some surgeons might consider the Akreos lens as a viable option due to its four-point fixation. However, in eyes with compromised corneas or retinas or in cases where anterior chamber air bubbles, silicone oil, or gas are anticipated, the risk of calcification outweighs its benefits.

We take issue with the following comment by Dr. Safran and colleagues: “Given the wide range of hydrophobic acrylic options available, one should question the rationale for using a hydrophilic acrylic lens at all.” While calcification is not a myth and we apologize if any inference to the contrary was drawn, we want to emphasize that hydrophilic IOLs should not be dismissed outright. Hydrophilic acrylic IOLs offer unique optical benefits and are suitable for many patients when used in the appropriate context. Evaluating IOLs based on a single, rare complication risks overlooking the broader advantages that each lens material provides. The decision to use one lens over another should be made based on a comprehensive understanding of the patient’s needs and the specific strengths of each IOL.

We also recognize that clinical experiences and practices inevitably shape our perspectives and the recommendations we share with colleagues. Referral centers, by their nature, often encounter more complex or unusual cases, including uncommon complications. Our practice is also a referral center, and while we have seen cases of IOL exchanges for refractive or optical issues, we have not encountered calcification in over 20,000 uses of hydrophilic lenses since 2016, as noted earlier. By sharing these experiences, we hope to contribute to a broader, more nuanced understanding of IOL performance across diverse clinical settings.

According to the latest Market Scope report, hydrophilic acrylic IOLs accounted for approximately 29% of IOLs implanted worldwide in 2024. This substantial market share highlights their established utility and underscores the need for a balanced understanding of their risks and benefits. We fully support calls for more rigorous peer-reviewed studies to further clarify the risks of calcification with hydrophilic IOLs and explore strategies to mitigate these risks.¹⁵ By continuing to gather data and share clinical insights, we can make well-informed decisions that optimize patient outcomes.

1. Wang X, Wu X, Dai Y, Huang Y. Intraoperative and postoperative intraocular lens opacifications: analysis of 42545 cases. J Ophthalmol. 2021;2021:1285947.

2. Dhital A, Spalton DJ, Goyal S, Werner L. Calcification in hydrophilic intraocular lenses associated with injection of intraocular gas. Am J Ophthalmol. 2012;153(6):1154-1160.e1.

3. Memmi B, Knoeri J, Bouheraoua N, Borderie V. Intraocular lens calcification after pseudophakic endothelial keratoplasty. Am J Ophthalmol. 2023;246:86-95.

4. Darcy K, Apel A, Donaldson M, et al. Calcification of hydrophilic acrylic intraocular lenses following secondary surgical procedures in the anterior and posterior segments. Br J Ophthalmol. 2019;103(12):1700-1703.

5. Werner L, Wilbanks G, Nieuwendaal CP, et al. Localized opacification of hydrophilic acrylic intraocular lenses after procedures using intracameral injection of air or gas. J Cataract Refract Surg. 2015;41(1):199-207.

6. Yildirim TM, Auffarth GU, Łabuz G, Bopp S, Son HS, Khoramnia R. Material analysis and optical quality assessment of opacified hydrophilic acrylic intraocular lenses after pars plana vitrectomy. Am J Ophthalmol. 2018;193:10-19.

7. Morgan-Warren PJ, Andreatta W, Patel AK. Opacification of hydrophilic intraocular lenses after Descemet stripping automated endothelial keratoplasty. Clin Ophthalmol. 2015;9:277-283.

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9. Stringham J, Werner L, Monson B, Theodosis R, Mamalis N. Calcification of different designs of silicone intraocular lenses in eyes with asteroid hyalosis. Ophthalmology. 2010;117(8):1486-1492.

10. Renschler A, Kelkar N, Eid K, et al. Complications of foldable intraocular lenses requiring explantation or secondary intervention: 2022 survey with update of long-term trends. J Cataract Refract Surg. 2024;50(4):394-400.

11. Jones JJ, Jones YJ, Jin GJ. Indications and outcomes of intraocular lens exchange during a recent 5-year period. Am J Ophthalmol. 2014;157(1):154-162.e1.

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14. Rongé LJ. Opacification of IOLs: a problem often misdiagnosed? EyeNet Magazine. September 1, 2005. Accessed February 10, 2025. https://www.aao.org/eyenet/article/opacification-of-iols-problem-often-misdiagnosed

15. Huang Q, Cheng GP, Chiu K, Wang GQ. Surface modification of intraocular lenses. Chin Med J (Engl). 2016;129(2):206-214.

16. Bainbridge JW, Teimory M, Tabandeh H, et al. Intraocular lens implants and risk of endophthalmitis. Br J Ophthalmol. 1998;82(11):1312-1315.

17. Łabuz G, Knebel D, Auffarth GU, et al. Glistening formation and light scattering in six hydrophobic-acrylic intraocular lenses. Am J Ophthalmol. 2018;196:112-120.

18. Werner L, Wallace KJ, Balendiran V, Shumway C, Ellis N, Mamalis N. Surface deposits mimicking calcification on a hydrophobic acrylic intraocular lens. J Cataract Refract Surg. 2019;45(7):1036-1039.

19. Bouvarel H, Agard E, Billant J, et al. Long-term real-life outcomes of the Clareon hydrophobic intraocular lens: the Clarte study in 191 eyes: 3-years real-life outcomes of the Clareon intraocular lens. BMC Ophthalmol. 2024;24(1):133.

20. Colin J, Orignac I, Touboul D. Glistenings in a large series of hydrophobic acrylic intraocular lenses. J Cataract Refract Surg. 2009;35(12):2121-2126.

21. Tognetto D, Toto L, Sanguinetti G, Ravalico G. Glistenings in foldable intraocular lenses. J Cataract Refract Surg. 2002;28(7):1211-1216.

22. Colin J, Praud D, Touboul D, Schweitzer C. Incidence of glistenings with the latest generation of yellow-tinted hydrophobic acrylic intraocular lenses. J Cataract Refract Surg. 2012;38(7):1140-1146.

23. Nieuwendaal CP, van der Meulen IJ, Patryn EK, Werner L, Mourits MP, Lapid-Gortzak R. Opacification of the intraocular lens after Descemet stripping endothelial keratoplasty. Cornea. 2015;34(11):1375-1377.

24. Mishra AV, Martens R, Loh GK, Somani R, Greve MDJ, Seamone ME. Clinical outcomes of pars plana vitrectomy and polytetrafluoroethylene (Gore-Tex) scleral fixation of a monofocal aspheric intraocular lens (Akreos AO60). J Vitreoretin Dis. 2024;8(5):540-545.

25. Zyablitskaya M, Hong E, Chen RWS, Chang S, Suh LH. Outcomes of four-point suture fixated and two-point sutureless posterior chamber IOLs combined with pars plana vitrectomy. BMC Ophthalmol. 2022;22(1):57.

26. Zheng H, Tsougranis G, Sanchez G, Mantopoulos D, Miller D. Postoperative complication rates by haptic fixation distance from limbus in sutureless intrascleral intraocular lens fixation. Invest Ophthalmol Vis Sci. 2022;63(7):2866.

27. Watane A, Botsford BW, Sood AB, et al. Scleral-sutured intraocular lens dislocations secondary to eyelet fractures. Am J Ophthalmol. 2021;221:273-278.

28. Czajka MP, Frajdenberg A, Stopa M, Pabin T, Johansson B, Jakobsson G. Sutureless intrascleral fixation using different three-piece posterior chamber intraocular lenses: a literature review of surgical techniques in cases of insufficient capsular support and a retrospective multicentre study. Acta Ophthalmol. 2020;98(3):224-236.