[The Effect of Cataract Surgery on the Reproducibility and Outcome of Optical Coherence Tomography Measurements of Macular and Retinal nerve Fibre Layer Thickness]. / Vliv operace katarakty na merení tloustky sítnice a vrstvy nervových vláken pomocí optické koherentní tomografie a na reprodukovatelnost optické koherentní tomografie.

INTRODUCTION: Optical coherence tomography (OCT) is a non-invasive imaging technique used for the examination of the macula and peripapillary retinal nerve fibre layer (RNFL), the result of which may be affected by the quality of the scanned image. The aim of our study was to assess the influence of uncomplicated cataract extraction on the measurement of macular and RNFL thickness with OCT and to determine the reproducibility of this method before and after cataract surgery in a group of healthy people. We also evaluated the effect of different intraocular lenses (IOL) (with/without yellow filter) on the reproducibility of the OCT examination. METHODS: The study group included 51 eyes of 51 patients who underwent cataract surgery with posterior chamber IOL implantation. Macular and RNFL thickness were measured with spectral domain OCT (Optovue, Model RT 100) one week before surgery, and postoperatively after one and six months. Three OCT scans were performed at each visit to assess the reproducibility of the measurement. Data were statistically processed. RESULTS: Analysis of the changes in macular and RNFL thickness showed a significant increase in retinal thickness, with the maximum increase one month after surgery, and regression of this thickening six months after surgery. Reproducibility of OCT examination improved significantly after cataract surgery, even though the preoperative values were of low coefficient of variance and therefore of high accuracy. No difference was found in the use of different intraocular lenses on the reproducibility of the OCT examination. CONCLUSION: The presence of cataract affects the OCT measurement of macular and RNFL thickness. The reproducibility of the method significantly improves after cataract surgery. It is likely that the increase in macular and RNFL thickness after cataract removal is partly due to improvement in the quality of the scanned image and thus to the greater accuracy of the OCT examination. KEY WORDS: optical coherence tomography, glaucoma, cataract, macular thickness, retinal nerve fibre layer thickness.

[Myopia or hyperopia?]. / Myopie nebo hypermetropie?

INTRODUCTION: The study describes cases of patients screened for worse vision and headaches. We are trying to point out we can measure minus diopters even at latent hypemetropes. These patients come to a doctor for a variety of problems that may be caused by inadequate correction of ametropia. It is necessary to know about this possibility, and rather perform cycloplegia in sporadic cases. METHODS: Patients were measured at autorefractometer without mydriasis, and then after using UNITROPIC 1% or CYCLOGYL 1%. Both of these substances induce cycloplegia. Visual acuity with the best correction was tested with and without cycloplegia. RESULTS: After cycloplegia, a significant change in both objective and subjective refraction was detected in most of the selected patients. This change was within the meaning of a shift to hyperopia. Subsequent adjustment correction led to resolving of problems. CONCLUSION: The work should highlight the necessity of an individual approach of prescription of the best correction. Not always an autorefractometer gives correct information, the real-needed correction is completely different in some cases.

[Comparison of central corneal thickness and keratometric measurements using the Scheimpflug HR imaging system, laser interferometry, automatic keratometry and ultrasound pachymetry]. / Srovnání merení tloustky a zakrivení rohovky pomocí Scheimpflugovy kamery, laserové interferometrie, automatické keratometrie a ultrazvukové pachymetrie.

INTRODUCTION: The aim of our study was to compare keratometry and central corneal thickness measurements obtained with three different ophthalmic devices and to decide if they can be used interchangeably in clinical practice. METHODS: 43 healthy persons were included in the study (29 women and 14 men, average age 25 ± 3.5 years). Central corneal thickness (CCT) was measured with the Scheimpflug HR imaging system (Pentacam), Allegro BioGraph and with ultrasound pachymetry (RXP OcuScan). Keratometry in two main meridians of the cornea (K1, K2) was measured with Pentacam, Allegro BioGraph and automated keratometry. RESULTS: The mean difference in K1-readings was 0.01 ± 0.31 D for BioGraph vs. automated keratometry, 0.06 ± 0.23 D for BioGraph vs. Pentacam and 0.05 ± 0.34 D for automated keratometry and Pentacam. The mean difference in K2-readings was 0.29 ± 0.45 D for BioGraph vs. automated keratometry, 0.11 ± 0.28 D for BioGraph vs. Pentacam and 0.19 ± 0.44 D for automated keratometry and Pentacam. The interdevice differences were in all cases statistically significant (p < 0.05). The mean difference in CCT was 4.57 ± 7.84 µm for BioGraph vs. ultrasound, 4.33 ± 7.55 µm for BioGraph vs. Pentacam and 8.90 ± 7.49 µm for ultrasound vs. Pentacam. The interdevice differences in CCT were also statistically significant (p < 0.05). CONCLUSION: Our results suggest that the measurements of keratometry and CCT may differ significantly between the tested machines and therefore should not be used interchangeably in clinical practice.