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

Abstract

BackgroundLaboratory analysis and optical quality assessment of explanted hydrophilic intraocular lenses (IOLs) with clinically significant opacification after posterior lamellar keratoplasty (DMEK and DSAEK).MethodsThirteen 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).ResultsIn 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.ConclusionsThe 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.

Assessment of straylight and the modulation transfer function of intraocular lenses with centrally localized opacification associated with the intraocular injection of gas

“…2, 5, 9-12, 17, 18 Although numerous studies on histological examination have been performed, 2, 5, 7, 9-12, 17, 18 little can be found on the optical quality of the affected IOLs. 7,11 The optical performance of opacified lenses has been studied by means of light scattering (straylight) measurements, [21][22][23] and quality metrics derived from the point spread function, such as the modulation transfer function (MTF) and the Strehl ration (SR). [24][25][26][27] Studies on straylight from different types of IOL opacification such as calcification, snow-flake degeneration, and glistenings, have shown that straylight is a very sensitive measure to detect the presence of IOL pathology.…”

“…The lenses were stained for Calcium by means of the Alizarin and von Kossa method using a protocol that has been described in detail in recent articles. 7,11,30 Image analysis…”

“…Intraocular lens (IOL) opacification is a serious condition that may degrade patients' vision. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Although opacification has often been associated with hydrophilic IOLs, 2, 5, 7, 9-15, 17, 18 this postoperative complication has also been reported in other lens materials. 1,3,6,16 Studies on calcification of hydrophilic acrylic IOLs have pointed to several factors that may be related to the onset of opacification, such as lens packaging, 4 ophthalmic viscosurgical device, 8 surgical technique, 19 patient related conditions, 6 and most recently, intracameral injection of gas.…”

Systematic review of potential causes of intraocular lens opacification

“…Another reason why the evaluated studies did not achieve a high score with the Pierson tool was the lack of data in their methodology or results, such as the type of lens implanted or how the cataract surgery was carried out . These pieces of information are very relevant and should be considered, as differences in the polymers with which they are made may be crucial for a better understanding of the exact mechanisms of opacification.…”

“…Of the 45 articles, five did not fulfil the inclusion criteria and were excluded from further analysis. The remaining included articles numbered 40 and were analysed using the Pierson tool …”