[Pupil centroid shift: Marketing tool or essential clinical parameter?]. / Verschiebung des Pupillenzentroids : Marketing oder klinisch relevanter Parameter?

BACKGROUND: Pupil centroid shift (PCS) is an easily measured parameter which is rarely taken into consideration when planning surgery. PURPOSE: The aim of this study was to determine the physiological range of PCS and to evaluate its role in refractive and cataract surgery. METHODS: The pupil center was measured in 103 eyes of 103 patients using the newest PCS module of the Allegro Topolyzer Vario (Version 1.76r58, Wavelight-Alcon, Erlangen, Germany) and the difference between a mesopic and a photopic environment was determined as PCSm. Additionally, these measurements were linearly extrapolated to pupil diameters of 2 mm and 7 mm (photopic-scotopic, PCSe). The statistical analysis included correlations between various demographic and topographic parameters and PCS. RESULTS: The average (± standard deviation) PCSm was 0.12 ± 0.08 mm with a range of 0.02-0.53 mm, with 2 eyes out of 95 (2%) having a PCSm of more than 0.4 mm. The extrapolated PCSe was 0.24 ± 0.16 mm and ranged from 0.03 to 0.78 mm, with 14 eyes out of 95 (15%) having a PCSe of more than 0.4 mm. Of the 95 eyes 3 (3%) showed a PCSe of more than 0.7 mm. There was no correlation between PCS with any of the demographic parameters tested. CONCLUSION: Up to 15% of the patients showed a PCS of more than 0.4 mm which requires a decision of the (refractive) ophthalmic surgeon as to whether the optical zone should be centered on the photopic or mesopic/scotopic pupil center. In the 3% of patients with a PCSe value greater than 0.7 mm, the implantation of multifocal intraocular lens (IOL) is not recommended.

[Complications of corneal cross-linking]. / Komplikationen der Vernetzung der Hornhaut.

BACKGROUND: More than 10 years after the clinical introduction of corneal cross-linking (CXL) the indications and contraindications are still not yet defined. Fundamental for such a list is the incidence of complications. METHODS: A PubMed search for complications of corneal crosslinking published up to March 2013 was carried out. RESULTS: The published complication rates ranged from 1 % to 10 % depending on the stage of keratoconus. Early postoperative complications were transient stromal haze, sterile infiltrates, endothelium decompensation, delayed epithelial healing and infectious keratitis. Stromal opacity can be a delayed postoperative event. CONCLUSIONS: Complications after corneal cross-linking treatment for keratoconus are rare but the management of these complications may need keratoplasty.

[Opacification of an intraocular lens: calcification of hydrophilic intraocular lenses after gas tamponade of the anterior chamber]. / Eintrübung einer Intraokularlinse: Kalzifizierung hydrophiler Intraokularlinsen nach Lufttamponade der Vorderkammer.

A patient with endothelial dystrophy was treated with Descemet stripping automated endothelial keratoplasty (DSAEK) combined with cataract extraction and implantation of a hydrophilic intraocular lens (IOL, Lentis-L312, Oculentis) but visual acuity dropped from 0.15 logMAR to 0.52 logMAR 18 months later due to calcification of the IOL. With new methods of lamellar corneal transplantation being used more frequently the number of necessary anterior chamber tamponades with air/gas are increasing. In cataract cases in which a gas tamponade and transplantation might be necessary later on (cornea guttata), hydrophilic IOLs should be avoided.

[Diagnosis of intraocular foreign bodies in multidetector-CT: influence of acquisition parameters on radiation dose and detectability]. / Intraokulare Fremdkörperdiagnostik in der Multidetektor-CT: Auswirkung der Akquisitionsparameter auf Strahlendosis und Erkennbarkeit.

PURPOSE: Determination of the influence of acquisition and reconstruction parameters on radiation dose and detectability of intraocular foreign bodies using multidetector CT (MDCT). MATERIALS AND METHODS: Porcine eyes with intraocular foreign bodies of a 0.3-mm quartz fiber and a 0.1-mm steel wire as well as 0.5 ml of blood in the vitreous were investigated using MDCT. The tube current was 500, 250, 100, and 50 mAs; the collimation was 16 x 0.75 mm and 16 x 1.5 mm; and the pitch was 0.5 and 0.75. Image reconstruction was performed using a soft tissue (H30), a bone algorithm (H60 s), and thin (0.7 and 2 mm, respectively) and thick (2 and 4 mm, respectively) reconstruction increments. The resulting data sets were then used to determine the signal difference to noise ratio (SDNR) between the foreign body and adjacent vitreous. RESULTS: Changes in tube current resulted in a proportional change in the radiation dose but only in the SDNR within a range of 1:2. Reducing the collimation from 1.5 mm to 0.75 mm resulted in a doubling of the SDNR at an approximately identical radiation dose. The series with a lower pitch at the same dose per volume showed a slightly higher SDNR. Reconstruction using a bone algorithm and thin increments resulted in an increase in the mean SDNR by a factor of 1.8 to 2.3. CONCLUSION: When diagnosing small intraocular foreign bodies using MDCT, the following parameters can yield an adequate SDNR while minimizing radiation exposure: tube current 50 mAs, pitch 0.5, collimation 16 x 0.75, bone algorithm, and reconstruction increment 0.7 mm.