Silicone oil content in ophthalmic viscosurgical devices

Localized calcification of hydrophilic acrylic intraocular lenses after posterior segment procedures

PURPOSE

To describe the clinical and laboratory findings in a series of cases of hydrophilic acrylic intraocular lens (IOL) opacification after posterior segment procedures.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, USA.

DESIGN

Experimental study.

METHODS

Thirty hydrophilic acrylic IOLs were explanted after various posterior segment procedures (pars plana vitrectomy, intravitreal anti-vascular endothelial growth factor injections) because of localized central anterior surface and subsurface optic opacification associated with decreased visual function. Once received by the laboratory in the dry state or in fixative by the explanting surgeons, microscopic, histochemical (alizarin red), and surface analysis (scanning electron microscopy [SEM], energy-dispersive X-ray spectroscopy [EDS]) evaluations were performed on the IOLs. The surgeons were sent a questionnaire to obtain information pertinent to each case.

RESULTS

Of the 30 explanted IOLs, 9 hydrophilic acrylic designs from 7 different manufacturers were identified. Gross microscopy and light microscopy showed granular deposits in a dense round pattern of distribution within the margins of the capsulorhexis or pupil on the anterior surface/subsurface of the IOLs. The granules stained positive for calcium with alizarin red. On SEM coupled with EDS, the granular deposits were found to comprise calcium and phosphate.

CONCLUSIONS

A localized pattern of anterior surface/subsurface calcification was seen on hydrophilic acrylic IOLs from various manufacturers. The calcification resembled the pattern seen on calcified IOLs after anterior segment procedures using intracameral injections of air or gas. This calcification of hydrophilic acrylic IOLs is likely the result of blood-aqueous barrier breakdown from repeated intraocular procedures.

Large-scale opacification of a hydrophilic/hydrophobic intraocular lens

PURPOSE

To determine the prevalence and risk factors related to the opacification of the LS-502-1 intraocular lens.

METHODS

Cross-sectional study including patients submitted to cataract surgery between January 2010 and March 2012, with implantation of the LS-502-1 intraocular lens. Past medical history was registered and a complete ophthalmologic evaluation, that included best-corrected visual acuity, slit-lamp examination and fundoscopy, was performed. Anterior segment photographs were taken whenever intraocular lens opacification was present.

RESULTS

One hundred and sixty-nine eyes of 154 patients were included, mean age 78.5 ± 7.9 years. The average follow-up after intraocular lens implantation was 65.6 ± 10.0 months. Intraocular lens opacification was seen in 53.3% (n = 90) and presented as one of four different patterns: peripheral (15.6%, n = 14), central (4.4%, n = 4), diffuse (71.1%, n = 64) and superficial white deposits (8.9%, n = 8). There was no statistically significant association with systemic or ophthalmic conditions. In patients with bilateral implantation, intraocular lens opacification in one eye was significantly related to intraocular lens opacification in the fellow eye. A significant variability in opacification was found across intraocular lens serial numbers: the odds ratio for opacification in intraocular lens with serial number beginning with 200003 was 6.0 when comparing with the remaining lenses.

CONCLUSION

The opacification prevalence of the LS-502-1 intraocular lens was 53.3%, which is the highest ever described for any intraocular lens model. Our results suggest that this occurrence is secondary to an interaction between unknown patient variables and problems related to intraocular lens manufacturing and storage procedures.

Intraocular lens dystrophic calcification after trans-scleral diode laser treatment for a cyclodialysis cleft

Purpose

To describe a case of intraocular lens (IOL) dystrophic calcification as a complication of trans-scleral diode laser successfully used to treat a post-trabeculectomy cyclodialysis cleft.

Observations

A 76-year-old male with primary open angle glaucoma and pseudophakia (+19.0D Akreos M160L, Bausch & Lomb) was evaluated for vision impairment 4 months post-trabeculectomy complicated by a cyclodialysis cleft of his right eye. The patient was successfully treated with trans-scleral diode laser. After this treatment IOL opacification developed. Slit lamp examination and color photography of the anterior segment was performed prior to exchange of the opacified IOL. The explanted IOL underwent star testing, macroscopic imaging, phase contrast and scanning electron microscopy in addition to energy dispersive x-ray spectroscopy.

Confluent IOL deposits developed 4 months after trans-scleral diode laser treatment requiring IOL exchange. Star optical testing of the explanted IOL showed disruption of the diffraction image. An asymmetric pattern of deposition was congruent with the laser treatment quadrant. The subsurface location and discrete nature of the deposits were seen on phase contrast and electron microscopy. Energy dispersive x-ray spectroscopy demonstrated a predominance of calcium/phosphate in the deposits. We are unaware of previous reports in the literature of IOL dystrophic calcification occurring as a complication of trans-scleral diode laser treatment for a post-trabeculectomy cyclodialysis cleft.

Conclusion and importance

Delayed postoperative IOL dystrophic calcification in our case may have been from a combination of IOL biomaterial susceptibility to diode laser energy; damaged IOL material providing a nidus for calcific nucleation; and blood ocular barrier breakdown altering aqueous composition. We suggest that pseudophakia should influence the consideration of diode laser as treatment of a cyclodialysis cleft.

Rapid detection of bacterial endotoxins in ophthalmic viscosurgical device materials by direct analysis in real time mass spectrometry

Bacterial endotoxins are lipopolysaccharides bound to the bacterial cell wall and released when bacteria rupture or disintegrate. Possible contamination of endotoxin in ophthalmic devices can cause a painful eye inflammation or result in toxic anterior segment syndrome after cataract surgery. Measurement of bacterial endotoxin in medical device materials is difficult since endotoxin binds with polymer matrix and some of the materials are very viscous and non-water soluble, where traditional enzyme-based Limulus amebocyte lysate (LAL) assay cannot be applied. Here we propose a rapid and high throughput ambient ionization mass spectrometric (MS) method using direct analysis in real time (DART) for the evaluation of endotoxin contamination in medical device materials. Large and structurally complex endotoxin instantaneously breaks down into low-mass characteristic fragment ions using DART and is detected by MS in both positive and negative ion modes. This method enables the identification and separation of endotoxin from medical materials with a detection limit of 0.03 ng mL^-1 endotoxins in aqueous solution. Ophthalmic viscosurgical device materials including sodium hyaluronate (NaHA), non-water soluble perfluoro-n-octane (PFO) and silicone oil (SO) were spiked with different known concentrations of endotoxin and analyzed by DART MS, where the presence of endotoxin was successfully detected and featured small mass fragment ions were generated for NaHA, PFO and SO as well. Current findings showed the feasibility of measuring endotoxin contamination in medical device materials using DART-MS, which can lead to a one-step analysis of endotoxins in different matrices, avoiding any potential contamination during sample pre-treatment steps.

Retention of silicone oil droplets from ophthalmic viscosurgical devices in the drainage angle of 2 eyes

We report the outcome in 2 eyes of 2 patients with retained silicone oil droplets in the anterior chamber drainage angle after the use of an ophthalmic viscosurgical device (OVD) during cataract surgery. Silicone oil droplets were observed when the OVD was injected into the anterior chamber during phacoemulsification. Despite removal by irrigation and aspiration, droplets were observed in the anterior chamber during the immediate postoperative period. At 15 months, they were observed in the drainage angle. The retained silicone did not produce untoward side effects in the eyes. Silicone oil is a common contaminant in OVDs but appears to be inert and harmless when retained in small amounts in the anterior chamber drainage angle.

Toxic anterior segment syndrome and possible association with ointment in the anterior chamber following cataract surgery

PURPOSE

To report clinical and laboratory findings of 8 cases of toxic anterior segment syndrome (TASS) related to an oily substance in the anterior chamber of patients following cataract surgery with intraocular lens (IOL) implantation.

SETTING

John Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

METHODS

Eight patients had uneventful phacoemulsification by the same surgeon via clear corneal incisions with implantation of the same 3-piece silicone IOL design. Postoperative medications included antibiotic/steroid ointment and pilocarpine gel; each eye was firmly patched at the end of the procedure. On the first postoperative day, some patients presented with diffuse corneal edema, increased intraocular pressure, and an oily film-like material within the anterior chamber coating the corneal endothelium. The others presented with an oily bubble floating inside the anterior chamber, which was later seen coating the IOL. Additional surgical procedures required included penetrating keratoplasty, IOL explantation, and trabeculectomy. Two corneal buttons were analyzed histopathologically. Two explanted IOLs had gross and light microscopic analyses (as well as surface analyses of 1 of them), and 4 other explanted IOLs had gas chromatography-mass spectrometry.

RESULTS

Pathological examination of the corneas showed variable thinning of the epithelium with edema. The stroma was diffusely thickened and the endothelial cell layer was absent. Evaluation of the explanted IOLs confirmed the presence of an oily substance coating large areas of their anterior and posterior optic surfaces. Gas chromatography-mass spectrometry of the lens extracts identified a mixed chain hydrocarbon compound that was also found in the gas chromatography-mass spectrometry analyses of the ointment used postoperatively.

CONCLUSIONS

The results indicate that the ointment gained access to the eye, causing the postoperative complications described. These cases highlight the importance of appropriate wound construction and integrity, as well as the risks of tight eye patching following placement of ointment.

Late opacification of a silicone intraocular lens caused by ophthalmic ointment

A 55-year-old man had uneventful phacoemulsification with implantation of a 3-piece silicone intraocular lens (IOL). Postoperative medications included antibiotic-steroid drops and ointments. Eight months postoperatively, the patient started having recurrent episodes of anterior chamber inflammatory reaction. Suspicion that lens instability was causing the reactions led to a lens repositioning procedure 11 months after the initial surgical implantation and again at 13 months. Eighteen months postoperatively, the IOL had a "greasy" film. Despite antiinflammatory and antibiotic treatment, the clinical outcome did not improve. Twenty-seven months after implantation, the lens was exchanged with a hydrophilic acrylic IOL. The course after the exchange was uneventful. The explanted lens was examined by gross and microscopic evaluations, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and gas chromatography-mass spectrometry (GC-MS) using electronic ionization. Gross and microscopic evaluations confirmed the presence of a thin, oily film covering the IOL optic surface. Surface analyses at the level of the oily substance showed unspecific peaks of sodium, chloride, and potassium. The GC-MS analysis showed the presence of compounds characteristic of hydrocarbons, including docosane, tricosane, and tetracosane, which are commonly found in the vehicle of ophthalmic ointments. The GC-MS analysis of 1 ointment used postoperatively found matching peaks, suggesting deposition of those compounds on the IOL.

Role of silicon contamination on calcification of hydrophilic acrylic intraocular lenses

PURPOSE

To verify the presence of the element silicon on hydrophilic acrylic intraocular lenses (IOLs) explanted because of calcification.

DESIGN

Interventional case series with clinicopathological correlation.

METHODS

Twenty explanted IOLs with surface deposits (MemoryLens), and 20 with deposits mostly within their optic substance (SC60B-OUV and Aqua-Sense; 10 each) were used. After gross, microscopic, and histochemical analyses to confirm the presence of deposits, the lenses underwent scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) for elemental composition, on the external surface of MemoryLens IOLs, and on the surface and internal substance of SC60B-OUV and Aqua-Sense IOLs. The weight percentage of the element silicon was obtained at the level of deposits, and at adjacent deposit-free areas in all lenses.

RESULTS

Scanning electron microscopy (SEM) coupled with EDS confirmed that the composition of the deposits was calcium/phosphate in all cases. The element silicon was found in all 40 lenses, on all areas analyzed. The silicon weight percentage was higher at the level of the deposits. The presence of aluminum on five MemoryLens IOLs, and in most of the SC60B-OUV and Aqua-Sense lenses might be related to scattering from the aluminum mounting stubs used for surface analyses.

CONCLUSIONS

Silicone compounds have been implicated in the calcification of another hydrophilic acrylic design (Hydroview). They may also have a role in the calcification of other hydrophilic acrylic IOLs. Further investigation on the relationship between the presence of the element silicon and the silicone compounds found on calcified hydrophilic acrylic lenses is necessary.