[Reproducibility of subjective refraction measurement]. / Zur Reproduzierbarkeit von Refraktionsbestimmungen.

BACKGROUND: Reproducibility of subjective refraction measurement is limited by various factors. The main factors affecting reproducibility include the characteristics of the measurement method and of the subject and the examiner. METHODS AND RESULTS: This article presents the results of a study on this topic, focusing on the reproducibility of subjective refraction measurement in healthy eyes. The results of previous studies are not all presented in the same way by the respective authors and cannot be fully standardized without consulting the original scientific data. To the extent that they are comparable, the results of our study largely correspond largely with those of previous investigations: During repeated subjective refraction measurement, 95% of the deviation from the mean value was approximately ±0.2 D to ±0.65 D for the spherical equivalent and cylindrical power. The reproducibility of subjective refraction measurement in healthy eyes is limited, even under ideal conditions. CONCLUSION: Correct assessment of refraction results is only feasible after identifying individual variability. Several measurements are required. Refraction cannot be measured without a tolerance range. The English full-text version of this article is available at SpringerLink (under supplemental).

[Comparison of different optical techniques for determination of the dimensions of anterior ocular segment]. / Vergleich verschiedener optischer Verfahren zur Vermessung der Dimensionen des okulären Vorderabschnitts.

BACKGROUND: The evaluation of the anterior ocular chamber sections along the optical axis/axis of vision has been carried out using single-line partial coherence interferometry for many years. Now, new technologies such as the Scheimpflug-technique of the Pentacam (Oculus Optikgeräte GmbH, Wetzlar) and the optical coherence tomography of the Visante OCT (Carl Zeiss Meditec AG, Jena) allow the two-dimensional imaging of the anterior ocular segment in addition to goniometry and ultrasonic biomicroscopy. PATIENTS/MATERIALS AND METHODS: The internal anterior chamber depth, central corneal thickness, angle-to-angle distance, and nasal and temporal anterior chamber angles of eight eyes (four patients) were examined using the Visante OCT and the Pentacam at three measurement periods within three days as part of a reproducibility study. In a comparative clinical trial on 97 eyes (53 patients), three to five measurements were made of the same parameters used in the reproducibility study, as well as external anterior chamber depths and white-to-white distances. RESULTS: The imaging techniques show high reproducibility with coefficients of variation up to 5.05%. The biometry instruments returned significantly different measuring results for the internal anterior chamber depth, corneal thickness and anterior chamber angle. Compared to the IOLMaster, the Visante OCT and the Pentacam produced external anterior chamber depths which were larger by 0.10 mm on average. Compared to the ACMaster, the measured internal anterior chamber depths were 0.01 mm and 0.03 mm smaller. The mean central corneal thickness measured with the Visante OCT was 3 +/- 5 microm smaller than the measured values obtained using the ACMaster. Compared to both these devices, the Pentacam produced central corneal thickness that was more than 20 microm larger. Both the Visante OCT and the Pentacam determined angle-to-angle-distances that were up to 1.3 mm smaller and up to 1.6 mm bigger than white-to-white-distances with the IOLMaster and ACMaster. On average, the anterior chamber angle measured with the Pentacam was larger 5.5 +/- 5.8 degrees (nasal) and 6.5 +/- 6.7 degrees (temporal) than the results provided by the Visante OCT. CONCLUSIONS: The Pentacam and Visante OCT imaging biometry instruments enabled high reproducibility and highly precise measurements of intraocular distances and displays of the anterior ocular segment.

Filtering bleb function after clear cornea phacoemulsification: a prospective study.

AIM: To evaluate the influence of clear cornea phacoemulsification on filtering bleb morphology, function, and intraocular pressure (IOP) in glaucomatous eyes with previously successful filtering surgery. METHODS: The clinical course of 30 patients (30 eyes) who underwent clear cornea phacoemulsification after successful filtering glaucoma surgery was prospectively evaluated. Mean IOP and filtering bleb morphology (standardised assessment criteria and score 0-12, 12 = optimum) were determined before surgery, and 3 days, 6 months, and 12 months after surgery. The control group consisted of 36 patients with glaucoma after clear cornea phacoemulsification without previous filtering surgery. RESULTS: Mean IOP increased after phacoemulsification by about 2 mm Hg (preoperatively 14.28 (SD 3.71) mm Hg, 12 months postoperatively 16.33 (3.31) mm Hg, p = 0.006). 15 patients (50%) showed an IOP increase of >2 mm Hg, 11 patients (36.7%) had no IOP difference (within 2 mm Hg), and in four patients (13.3%) IOP decreased >2 mm Hg. Mean score of filtering bleb morphology 1 year after surgery decreased from 9.5 to 9.0 (p = 0.154). In three of 30 preoperatively IOP regulated eyes the postoperative IOP was 21 mm Hg. The control group showed an average IOP decrease of 2.01 mm Hg (p = 0.014) 12 months after cataract surgery. CONCLUSION: An increase in IOP was found 1 year after phacoemulsification in half of the filtered glaucomatous eyes. IOP in glaucomatous eyes without previous filtering surgery decreased in the same period. Cataract extraction using clear cornea phacoemulsification may be associated with a partial loss of the previously functioning filter and with an impairment of filtering bleb morphology.

[Quantitative and objective follow-up of papilledema with the Heidelberg Retina Tomograph]. / Quantitative und objektive Verlaufskontrolle der Papillenschwellung mit dem Heidelberg-Retina-Tomographen.

UNLABELLED: The Heidelberg retina tomograph (HRT) is a new instrument to analyze the three-dimensional structure of the retina. It is based on confocal laser scanning technology. Scientific interest has so far focused on the follow-up of glaucomatous optic nerve head damage. As parameters such as cup depth and cup volume can be reproduced with a high degree of accuracy, this new instrument may prove to be an excellent tool to follow up swelling of the optic disk. PATIENTS AND METHOD: A total of 21 patients suffering from optic disk swelling of various etiologies were included in a pilot study. Measurements were taken at six different time points. The maximum optic disk elevation and the volume of swelling were evaluated. Visual acuity and the visual field were determined, and fundus photographs were taken. RESULTS: A reduction in optic disk swelling over time may be demonstrated by both morphological parameters and correlates with improvement in fundus changes. The change in the volume of swelling is greater than the change in maximum disk elevation. The course of optic disk swelling differs between patients with anterior ischemic optic neuropathy and those with pseudotumor cerebri. No correlation was found between our measurements with the HRT and functional parameters (visual acuity and visual field). CONCLUSION: The HRT is a good tool for the follow-up of optic disk swelling, particularly optic disk elevation due to increased intracranial pressure.