[Effects of Nd:YAG microexplosions on heparin-coated PMMA intraocular lenses]

Abstract

Surface modification of intraocular lenses (IOL) have improved the quality of cataract surgery. Heparin surface-modified (HSM) IOL are implanted for special indications (e.g., recurrent uveitis, cataract surgery for children, preoperative synechia) because of decreased postoperative inflammatory reactions and higher long-term biocompatibility. Nevertheless, secondary cataract, precipitates and fibrinous membranes appear. The YAG laser is used for treatment.

Methods: PMMA intraocular lenses with or without a heparin monolayer were exposed to Nd:YAG laser. The experiment was performed under BSS using different energy levels and distances to the IOL. The heparin monolayer was stained with toluidin blue. Subsequently, the surface of the intraocular lenses was examined with light and scanning electron microscopy.

Results: The YAG laser marks of HSM IOL and PMMA IOL showed no morphological differences. Microexplosions and pressure waves of the Nd:YAG laser cleared parts of the heparin monolayer in the area of the laser spots dependent on energy distance to the IOL. Even "breakdown" behind the HSM IOL without any PMMA lesion shown circular destruction of the heparin monolayer.

Conclusions: The heparin surface defect of HSM IOL after YAG laser treatment should be taken into consideration, because a decreased heparin effect in vivo could be possible.