Laboratory analyses of two explanted hydrophobic acrylic intraocular lenses

Intraoperative and Postoperative Intraocular Lens Opacifications: Analysis of 42545 Cases

Purpose

To assess the types and causes of intraocular lens (IOL) turbidity in a tertiary eye center. Setting. Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China.

Design

Retrospective case series.

Methods

Patients who underwent uncomplicated phacoemulsification and IOL implantation for cataract between January 2015 and December 2019 were included. Medical records were reviewed of participants with intraoperative or postoperative IOL opacification for clinical data, artificial crystal materials, and causes of the opacification.

Results

A total of 42545 IOLs were implanted in the five years, comprising 25471 (66.0%) hydrophilic IOLs, 11881 (27.9%) hydrophobic IOLs, and 2601 (6.1%) hydrophilic-hydrophobic acrylic IOLs. Among the operated eyes, 14 eyes (13 patients) experienced IOL opacification, which was permanent for 10 IOLs, including 7 (0.6%) hydrophilic IOLs (860UV) and 3 (0.2%) hydrophilic-hydrophobic acrylic IOLs (L-312). The mean interval between surgery and diagnosis of permanent opacification was 34.4 ± 18.4 (SD) months (range, 12 to 59 months). Permanent IOL clouding led to a statistically significant reduction in best corrected visual acuity (mean, 0.64 ± 0.4 logMAR; P < 0.004). Acute IOL clouding occurred in four eyes during the implantation of a hydrophilic-hydrophobic acrylic IOL of L-312, 809M, or 839M and returned to transparency several hours later. All four procedures were performed in winter, with the mean outside temperature being −5.75°C.

Conclusions

The rate of IOL opacification was 0.03%. Both delayed postoperative and acute intraoperative opacifications occurred with various characteristics in IOLs made of different materials and designs. Clinicians should be aware of this risk for cataract surgery.

Microscopic Characteristics of Late Intraocular Lens Opacifications

CONTEXT.—

The increases in overall life expectancy and in lens surgeries performed on younger patients have resulted in a significant increase in the anticipated duration of artificial intraocular lenses (IOLs) in the eye. Thus, the physicochemical properties of the IOL become a critical issue, and several types of postoperative IOL opacifications have been reported.

OBJECTIVE.—

To describe the microscopic characteristics of opacified IOLs. Glistenings and subsurface nanoglistenings are fluid-related phenomena developing mainly in hydrophobic acrylic IOLs and are associated with aqueous influx into the IOL matrix. Calcification presents in hydrophilic acrylic or silicone IOLs as deposits of hydroxyapatite or other phases of calcium. Snowflake degeneration is less common, and it manifests in older polymethyl methacrylate IOLs.

DATA SOURCES.—

PubMed and ScienceDirect databases were searched for the following keywords: intraocular lens, IOL, cataract surgery, phacoemulsification, opacification, glistening, subsurface nanoglistenings, calcification, snowflake degeneration. English-language articles published up to October 15, 2019 were included in the study. The manuscript contains mainly a literature review; however, it was supplemented with original investigations from the David J. Apple International Laboratory for Ocular Pathology.

CONCLUSIONS.—

Glistenings and subsurface nanoglistenings should be evaluated in a hydrated state and at room temperature; they manifest as microvacuoles sized from 1.0 to greater than 25.0 μm and less than 200 nm, respectively. Calcification deposits are situated on or underneath the surface of the IOL and can be stained with a 1% alizarin red solution or with the von Kossa method. Snowflake degeneration manifests as "particles" or "crystals," causing whitish IOL discoloration. Scanning electron microscopy or energy dispersive X-ray spectroscopy may improve the diagnostic accuracy.

Scanning electron microscopic features of explanted degraded hydrophobic acrylic intraocular lenses which were in vivo for a prolonged period

Purpose:

To study and document electron microscopic features in explanted hydrophobic microvacuoles affected acrylic intraocular lenses (IOL) which were in vivo for an average duration of 11 years.

Methods:

Scanning electron microscopic (SEM; Hitachi S 3000 N EXAX Genesis VP SEM) study of five explanted hydrophobic acrylic IOL which had clinically evident microvacuoles prior to explantation, was done. The IOLs were in vivo for a prolonged period and needed explantation for various indications. Only those hydrophobic acrylic IOLs which fulfilled the inclusion criteria were included. The findings were compared with control specimens.

Results:

The IOLs were in vivo for an average duration of 11.6 ± 4.21 years. The cause of explantation of IOL was subluxation in four cases and low visual acuity in one case. Bulk degradation and microvacuoles on cut sections throughout the IOL optics and undulating surface patterns over both the surfaces of the IOL has been documented in all the specimens. No such findings were noted in the control specimens where the surface and texture were homogenous.

Conclusion:

SEM findings of the structural changes in explanted IOL documented in the study demonstrate that hydrophobic acrylic IOL is degradable in vivo. Microvacuoles are a clinical manifestation of the structural changes that occur at a microscopic and molecular level. These changes are not seen in IOLs which have not undergone intraocular implantation. To our knowledge, a similar study of this kind has not been done.