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

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.

In vitro comparative optical bench analysis of a spherical and aspheric optic design of the same IOL model.

BACKGROUND: To analyse objective optical properties of the spherical and aspheric design of the same intraocular lens (IOL) model using optical bench analysis. METHODS: This study entailed a comparative analysis of 10 spherical C-flex 570 C and 10 aspheric C-flex 970 C IOLs (Rayner Intraocular Lenses Ltd., Hove, UK) of 26 diopters [D] using an optical bench (OptiSpheric, Trioptics, Germany). In all lenses, we evaluated the modulation transfer function (MTF) at 50 lp/mm and 100 lp/mm and the Strehl Ratio using a 3-mm (photopic) and 4.5-mm (mesopic) aperture. RESULTS: At 50 lp/mm, the MTF values were 0.713/0.805 (C-flex 570 C/C-flex 970 C) for a 3-mm aperture and 0.294/0.591 for a 4.5-mm aperture. At 100 lp/mm, the MTF values were 0.524/0.634 for a 3-mm aperture and 0.198/0.344 for a 4.5-mm aperture. The Strehl Ratio was 0.806/0.925 and 0.237/0.479 for a 3-mm and 4.5-mm aperture respectively. A Mann-Whitney U test revealed all intergroup differences to be statistically significant (p < 0.01). CONCLUSION: The aspheric IOL design achieved higher MTF values than the spherical design of the same IOL for both apertures. Moreover, the differences between the two designs of the IOL were more prominent for larger apertures. This suggests that the evaluated IOL provides enhanced optical quality to patients with larger pupils or working under mesopic conditions.

Removal of lymphangiectasis using high-frequency radio wave electrosurgery.

PURPOSE: To describe a novel technique using high-frequency radio wave electrosurgery (Ellman Surgitron Dual Frequency RF; Ellman International, Inc) for the management of lymphangiectasis. METHODS: Ablations were performed at the lowest power setting of 1 (of 100) in the cutting mode, producing the least amount of lateral heat. To prevent conjunctival hemorrhage, ablation was initiated immediately before introducing the tip of a needle electrode into the subconjunctival tissue under the target area. After the tip of the electrode reached the target area, ablation was maintained for 1 to 2 seconds on the surrounding area and for a longer time on the dilated lymphatic vessels, until the target conjunctiva blanched. These ablations were performed cautiously with the fine electrode to avoid thermal injury to the adjacent scleral tissue. RESULTS: Persistent lymphangiectasis accompanied by accumulated fluid was successively treated with high-frequency radio wave electrosurgery. Surgical time was less than 5 minutes. There were no intraoperative complications. Fourier domain optical coherence tomography revealed resolution of the accumulated fluid and a decrease of dilated lymphatic vessels. Postoperatively, no notable complications, such as charring, scarring of Tenon capsule, or symblepharon resulting from excessive cauterization, were observed. CONCLUSION: High-frequency radio wave electrosurgery may be a safe, quick, and effective modality for the treatment of symptomatic lymphangiectasis patients.