Repeatability and agreement of Scheimpflug-based and swept-source optical biometry measurements.

PURPOSE: To evaluate the repeatability and comparability of biometry parameters between a Scheimpflug-based topography with axial length measurement (Pentacam AXL, Oculus, Wetzlar, Germany) and a swept-source optical biometry (IOLMaster 700, Carl Zeiss Meditec AG, Jena, Germany). METHODS: A total of 50 eyes from 50 adult subjects had biometry measurements in one session three times using the Pentacam AXL and the IOLMaster 700. Keratometry, anterior chamber depth (ACD) and axial length (AL) values were obtained by both devices. Mean keratometry (Kmean) was calculated and the corneal spherocylinder was converted into power vectors (J0, J45). Repeatability was assessed based on intraclass correlation coefficient (ICC). Agreement was evaluated by linear regression analysis and Bland-Altman analysis by calculating the mean difference and 95% limits of agreement (LoA). RESULTS: Assessment of intraoperator repeatability by means of ICC showed excellent reproducibility of measurements for both devices and all parameters examined ranging from 0.994 to 1.0. IOLMaster 700 exhibited significantly higher Kmean (p<0.001) and AL (p<0.001) values than the Pentacam AXL. Pentacam AXL showed significantly higher ACD (p<0.001) measurements than IOLMaster 700. There was no statistically significant difference of J0 (p=0.115) and J45 (p=0.255) values between Pentacam AXL and IOLMaster 700. CONCLUSIONS: Both devices provide high reproducible values for all parameters investigated. J0 and J45 values are statistically and clinically interchangeable between Pentacam AXL and IOLMaster 700. All other parameters are statistically different. In clinical practice, the differences for ACD and AL are to small and the values can be used interchangeable. However, Kmean values are clinically and statistically different and cannot be used interchangeable between the two devices.

The receptor for advanced glycation end products RAGE is involved in corneal healing.

Impaired corneal healing is still a major cause of blindness. As RAGE (receptor for advanced glycation endproducts) is involved in inflammation and wound healing in other tissues, we here investigated its relevance for corneal wound healing. Corneal re-epithelialization after alkaline injury was analysed in an ex-vivo approach with cultured, enucleated eyes from mice either of the C57Bl/6 NChR genotype (RAGE+/+) and mice of the same strain lacking the RAGE gene (RAGE-/-). The wound area was determined time dependently by fluorescence imaging using fluorescein staining. The eyes of RAGE-/- mice showed a significantly slower re-epithelialization than eyes of the RAGE+/- and the RAGE+/+ genotype. In immunohistochemistry, RAGE expression was increased in wounded corneas whereas the abundance of the RAGE ligand HMGB1 was unaffected, but an increase in S100b-like proteins was revealed upon injury. However, neither the addition of the RAGE agonist HMGB1 or an HMGB1 antagonising antibody nor bovine S100b protein to the culture medium of the wounded eyes had an effect on corneal wound closure in ex-vivo. Further gene expression analysis by RT-PCR demonstrated an increase in RAGE expression on the mRNA level, no significant regulation of HMGB1 and a differential regulation of the S100 gene family after alkaline burn of the cornea. In conclusion, RAGE is clearly involved in corneal re-epithelialization most probably mediated by signalling via S100 proteins.

Temporal and spatial expression pattern of Nnat during mouse eye development.

BACKGROUND: Neuronatin (Nnat) was initially identified as a highly expressed gene in neonatal mammalian brain. In this study, we analyze the spatial and temporal expression pattern of Nnat during mouse eye development as well as in the adult. METHODS: The expression of Nnat was analyzed on mRNA as well as protein level. The presence of Nnat transcripts in the adult retina was examined using reverse transcription-polymerase chain reaction (RT-PCR). Nnat protein expression was evaluated by Western blot and immunohistochemistry during eye development at embryonic day (E) 12, 15, 16 and postnatal day (P) 7, 14, 30 and 175 (adult). RESULTS: Immunohistochemical studies of the developing mouse eye revealed Nnat expression in embryonic and adult neuroretina as well as in corneal epithelial, stromal, endothelial cells and in lens epithelium. Expression of Nnat was detected from E12 onwards and was also present in adult eyes. CONCLUSIONS: The expression pattern suggests that Nnat may play an important role during eye development and in the maintenance of mature eye.

Evaluation of central corneal thickness after cataract surgery, penetrating keratoplasty and long-term soft contact lens wear.

PURPOSE: The aim of this study was to compare central corneal thickness (CCT) between corneas of normal healthy eyes (cNHE), corneas of eyes that had undergone cataract surgery by clear corneal phacoemulsification with implantation of an intracapsular intraocular lens (cIOL), corneal grafts after penetrating keratoplasty (gPK) and corneas of long-term soft contact lens wearers (cCL). METHODS: The study design was a consecutive cross-sectional trial. CCT was measured using rotating Scheimpflug camera (Pentacam, software version 1.16r04) in 80 cNHE, 79 cIOL, 46 gPK and 78 cCL. Analysis of variance (one-way ANOVA) was performed to compare differences of mean values between these four groups. Pearson's or Spearman's correlation coefficient (r) was determined between CCT value and age, follow up time after penetrating keratoplasty (timePK) or contact lens wearing time (timeCL). RESULTS: Means of CCT measurements were comparable between cNHE (mean CCT±standard deviation, 554±36µm), cIOL (551±40µm) and gPK (534±52µm) as determined by one-way ANOVA. Mean CCT values in cCL (537±37µm) were statistically significantly lower in comparison to cNHE (p=0.026, 95% CI=1.43-31.44). There was no linear correlation between age and CCT values of cNHE and cIOL (p=0.841, r=-0.031 and p=0.931, r=0.011, respectively). No linear relationship was determined between CCT values of cCL and timeCL (p=0.315, r=-0.125). CCT values of gPK did not correlate with timePK (p=0.738, r=0.054). CONCLUSIONS: The data reported here indicate that in the same statistical model among CCT values of cNHE, cIOL and gPK only long-term soft contact lenses (CL) wearer have significantly lower CCT measurements.