Surface Features of Used Intraocular Lenses

Cellular reaction on the anterior surface of poly(methyl methacrylate) intraocular lenses

PURPOSE

To assess the cellular reaction on the anterior surface of poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) implanted by phacoemulsification with continuous curvilinear capsulorhexis (CCC) or by extracapsular cataract extraction (ECCE) with a linear capsulotomy.

SETTING

Cataract and Refractive Surgery Research Unit. Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

METHODS

To document morphology, topography, and severity of the cellular reaction, specular microscopy of the anterior IOL surface was performed at 1 day, 1 week, and 1 and 3 months postoperatively in two parallel groups of 31 consecutive cataractous eyes operated on by phacoemulsification with CCC or by ECCE with a linear capsulotomy.

RESULTS

The local tissue response consisted of a nonspecific foreign-body reaction to the IOL and a lens epithelial cell reaction. The foreign-body reaction was significantly less severe in the phacoemulsification group than in the ECCE group, and the number of IOLs without inflammatory cells was significantly higher.

CONCLUSION

The foreign-body reaction to PMMA IOLs is significantly reduced when the lens is implanted by phacoemulsification with CCC. This could be of clinical benefit in high-risk eyes prone to the inflammatory complications of cataract surgery.

Continuous curvilinear capsulorhexis and intraocular lens biocompatibility

PURPOSE

To study the influence of continuous curvilinear capsulorhexis (CCC) on poly(methyl methacrylate) (PMMA) intraocular lens (IOL) biocompatibility.

METHODS

Biocompatibility was assessed by measuring the postoperative blood-aqueous barrier breakdown and the cellular reaction at the anterior capsule-IOL interface. In a prospective study, 30 consecutive eyes, normal except for having extracapsular cataract extraction (ECCE) with CCC by a single surgeon, has laser flare and cell measurements and specular microscopy of the anterior IOL surface at 1 day, 1 week, and 1 and 3 months postoperatively.

RESULTS

In addition to the foreign-body reaction previously described in eyes that had other capsulotomy types, the eyes in this study also had a lens epithelial cell (LEC) reaction. The severity of the foreign-body reaction and postoperative aqueous flare and cells was significantly less in eyes with an intact CCC than in those with rim tears in the capsulorhexis and in those having an ECCE with a linear or can-opener capsulotomy, as previously reported.

CONCLUSIONS

Continuous curvilinear capsulorhexis improves the biocompatibility of PMMA IOLs to a degree that could be of clinical benefit. In eyes with CCC, most cells seen on the anterior IOL surface were LECs.

Correlations between aqueous flare and cells and lens surface cytology in eyes with poly(methyl methacrylate) and heparin-surface-modified intraocular lenses

A prospective, single-surgeon study was performed on 59 patients randomized to receive a poly(methyl methacrylate) intraocular lens or a heparin-surface-modified lens after standardized endocapsular cataract surgery with a routine postoperative regimen. The anterior chamber laser flare and cell measurements and the cellular reaction on the anterior lens surface were monitored for a year following surgery. This report examines the correlations between the anterior chamber flare and cell reaction and the anterior IOL surface cellular reaction. The findings suggest that the early postoperative blood-aqueous barrier breakdown is primarily caused by surgical trauma; by one month the blood-aqueous barrier function is determined by inflammatory mediators released by small monocyte-derived cells on the IOL surface. Giant cells on the IOL surface did not correlate with aqueous flare, which suggests an insignificant capacity to release inflammatory mediators.

Pathology of fixation fibrosis on intraocular lenses

Ocular tissues frequently form a special kind of reactive fibrosis with distinct cellular strands that anchors prominent surface irregularities of lens implants--haptics, manipulation holes, or borders--to adjacent ocular structures and helps fixate the implant in the eye. The strands originate in reactive proliferation of chemotactically attracted sessile macrophages on the surface of lens implants. They are cellular in their early stages and may undergo secondary fibrosis or hyalinization. The formation of these strands is called "fixation fibrosis." An initial description of the pathology of this complicated process is presented.