[Hydrophobic surface properties of hydrophilic acrylic lenses do not protect against calcification]

Impact of Calcium and Phosphorus Levels on Optical Deterioration in Primary and Secondary Intraocular Lens Calcification

Purpose

The purpose of this study was to investigate the impact of calcium and phosphorus levels on optical deterioration in primary and secondary intraocular lens (IOL) calcification.

Methods

A total of 18 explanted IOLs, 10 with primary, and 8 with secondary calcification, were examined. Straylight and light loss were evaluated as predictors of optical impairment. The individual amount of calcium and phosphorus was determined using thermogravimetry followed by emission spectroscopy (ICP-OES). The relationship between calcification and optical impairment was investigated.

Results

Primary calcified IOLs contained significantly higher amounts of calcium and phosphorus compared to secondary calcified IOLs (calcium P < 0.02 and phosphorus P < 0.01), translating to greater light loss and significantly higher straylight mean values. In secondary calcification, light loss and straylight were highly dependent on calcium (r² = 0.90, P < 0.001 and r² = 0.70, P < 0.01) and phosphorus (r² = 0.66 and r² = 0.65, both P < 0.02), whereas these correlations were much lower in primary calcification (all r = 0.25, P > 0.05).

Conclusions

ICP-OES is the first methodology to precisely assess the calcium and phosphorus content in IOL calcification thus based on mass ratios allowing improved molecular characterization. Primary calcification showed higher amounts of calcium and phosphorus, translating to higher straylight and light loss and thus a higher risk for impairment of visual quality than secondary calcification.

Translational Relevance

This study is the first to quantify calcification and demonstrate the relationship to optical deterioration in IOLs, substantially contributing to understand how visual impairment arises in patients with calcified IOLs.

[Intraoperative Complications in Cataract Surgery]

Cataract surgery is frequently and successfully performed in the developed world. The indications for the operation have shifted on one hand towards healthier patients seeking freedom from glasses and on the other hand towards more complex cases. How should the patient be informed? What complications can occur intraoperatively, and what treatment options are available for these complications?This article offers a focus on conditions such as zonulopathy and pseudoexfoliation that can pose challenges to cataract surgery. It discusses the use of specialized tools such as capsular tension rings and capsular hooks and precise maneuvers to minimize stress on weakened zonules in order to ensure in-the-bag fixation of the IOL.Furthermore, the article addresses appropriate actions towards intraoperative complications such as anterior or posterior capsule ruptures and loss of nuclear fragments into the vitreous cavity.Exploring innovative advancements, this article presents the latest alternatives for intracapsular lens fixation, such as sutureless scleral fixation and emerging lens designs in cases where there is insufficient capsular support.Ultimately, the primary objective remains delivering optimal outcomes even for complex cases, and minimizing post-surgical issues. Numerous tools and techniques are available.

Opacification of Hydrophilic Acrylic Intraocular Lenses: Overview of Laboratory Methods for Histological Analysis and Replication of IOL Calcification

Opacification of intraocular lenses (IOLs) due to material changes is a serious complication that can compromise the good visual outcomes of uncomplicated cataract surgery. In hydrophobic acrylic IOLs, opacification can result from glistening formation, while in hydrophilic acrylic IOLs, there is a risk of calcification due to the formation of calcium phosphates within the polymer. Over time, various methods have been developed to investigate calcification in hydrophilic acrylic IOLs. The aim of this article is to provide an overview of standard histological staining and models used to simulate IOL calcification. Histological staining can be used to detect calcification and assess the extent of crystal formation. The development of in vivo and in vitro replication models has helped to identify the underlying pathomechanisms of calcification. In vivo models are suitable for assessing the biocompatibility of IOL materials. Bioreactors as an in vitro model can be used to investigate the kinetics of crystal formation within the polymer. The replication of IOL calcification under standardized conditions using electrophoresis allows for the comparison of different lens materials with respect to the risk of calcification. The combination of different analytical and replication methods can be used in the future to further investigate the pathomechanisms of calcium phosphate crystal formation and the influence of risk factors. This may help to prevent calcification of hydrophilic acrylic IOLs and associated explantation and complications.