Hydrophilic intraocular lens opacification after posterior lamellar keratoplasty - a material analysis with special reference to optical quality assessment

Abstract

Background: Laboratory analysis and optical quality assessment of explanted hydrophilic intraocular lenses (IOLs) with clinically significant opacification after posterior lamellar keratoplasty (DMEK and DSAEK).

Methods: Thirteen opacified IOLs after posterior lamellar keratoplasty, 8 after descemet stripping automated endothelial keratoplasty (DSAEK), 3 after descemet membrane endothelial keratoplasty (DMEK) and 2 after both DSAEK and DMEK were analysed in our laboratory. Analyses included optical bench assessment for optical quality, light microscopy, scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS).

Results: In all IOLs the opacification was caused by a thin layer of calciumphosphate that had accumulated underneath the anterior optical surface of the IOLs in the area spared by the pupil/anterior capsulorhexis. The calcifications lead to a significant deterioration of the modulation transfer function across all spatial frequencies of the affected IOLs.

Conclusions: The instillation of exogenous material such as air or gas into the anterior chamber increases the risk for opacification of hydrophilic IOLs irrespective of the manufacturer or the exact composition of the hydrophilic lens material. It is recommended to avoid the use of hydrophilic acrylic IOLs in patients with endothelial dystrophy that will likely require procedures involving the intracameral instillation of air or gas, such as DMEK or DS(A)EK.

Keywords: Cataract surgery; Complications; Cornea; Descemet membrane endothelial keratoplasty; Fuchs endothelial dystrophy; IOL explantation; Intraocular lens; Optical quality; Posterior lamellar keratoplasty.

Fig. 1

IOLs 1–7. Light microscopy images representing an overview of the IOL optic and higher magnification images with Alizarin Red and von Kossa stainings. Details and magnification as noted under each individual panel

Fig. 2

IOLs 8–13. Light microscopy images representing an overview of the IOL optic and higher magnification images with Alizarin Red and von Kossa stainings. Details and magnification as noted under each individual panel

Fig. 3

SEM-scans from cross-sections through the anterior optical surface (IOL 1–4 and 6–11), high magnification scan of the opacified anterior optical surface showing individual calcium deposits (IOL 5), low magnification overview of an IOL specimen showing the opacifications in the center of the anterior optical surface (IOL 12). Magnification and scale bar given in each individual panel

Fig. 4

Exemplary Element Mapping showing calcium (green) and phosphorus (magenta) within the deposits in IOL 5

Fig. 5

Exemplary elementary analysis (IOL 5) using energy dispersive X-ray spectroscopy showing the deposits to consist of calcium phosphate

Fig. 6

(a) Representative modulation transfer function (MTF) of an opacified IOL (IOL 6) showing a deterioration at all spatial frequencies. The green line represents the diffraction limit. Blue lines represent the measured MTF values in sagittal (solid blue line) and tangential (dashed blue line) planes. (b) Representative MTF of a clear monofocal aspheric IOL from hydrophilic acrylate (CT Asphina 409 MP, Carl Zeiss Meditec, Jena, Germany) taken in our laboratory for comparison. (c) USAF target image obtained through IOL 6 at standard lighting conditions showing a significant reduction in light transduction. (d) With light adjustment an acceptable image quality could be achieved