[Monochromatic aberration in accommodation. Dynamic wavefront analysis]. / Aberrationen höherer Ordnung bei Akkommodation. Dynamische Wellenfrontmessung.

BACKGROUND: Monochromatic aberrations may influence the visual acuity of the eye. They are not stable and can be affected by different factors. The subject of the following paper is the dynamic investigation of the changes in wavefront aberration with accommodation. METHOD: Dynamic measurement of higher and lower order aberrations was performed with a WASCA Wavefront Analyzer (Carl-Zeiss-Meditec) and a specially constructed target device for aligning objects in far and near distances on 25 subjects aged from 15 to 27 years old. RESULTS: Wavefront aberrations showed some significant changes in accommodation. In addition to the characteristic sphere reaction accompanying miosis and changes in horizontal prism (Z(1) (1)) in the sense of a convergence movement of the eyeball also occurred. Furthermore defocus rose (Z(2) (0)) and astigmatism (Z(2) (-2)) changed. In higher-order aberrations a decrease in coma-like Zernike polynomials (Z(3) (-1), Z(3) (1)) was found. The most obvious change appeared in spherical aberration (Z(4) (0)) which increased and changed from positive to negative. In addition the secondary astigmatism (Z(4) (-2)) and quadrafoil (Z(4) (4)) rise also increased. The total root mean square (RMS), as well as the higher-order aberrations (RMS-HO) significantly increased in accommodation which is associated with a theoretical reduction of visual acuity. An analysis of the influence of pupil size on aberrations showed significant increases in defocus, spherical aberration, quadrafoil, RMS and RMS HO by increasing pupil diameter. By accommodation-associated miosis, the growing aberrations are partially compensated by focusing on near objects. Temporal analysis of the accommodation process with dynamic wavefront analysis revealed significant delays in pupil response and changing of prism in relation to the sphere reaction. In accommodation to near objects a discrete time ahead of third order aberrations in relation to the sphere response was found. CONCLUSION: Using dynamic wavefront measurement achieved a sequential analysis of aberrations during accommodation. Significant changes in the lower and higher-order aberrations could be detected. These are additionally varied by the associated pupillary response. Moreover, the synchronicity of wave front reaction in the accommodation process was proven.

[The influence of eye movements on monochromatic wavefront aberrations]. / Aberrationen höherer Ordnung bei Blickbewegungen.

BACKGROUND: Wavefront-guided corneal surgery is a standard therapeutic option for correcting refractive errors. If the wavefront measured preoperatively is influenced by an incorrect alignment of the bulb, the ablation profile could be distorted and the quality of vision reduced. METHOD: Wavefront analysis was done on 49 eyes, examining the primary gaze of the bulb as well as abduction, adduction, elevation, and depression. RESULTS: The study demonstrated a significant influence of eye movements on astigmatic aberrations. Horizontal eye movements have a stronger influence than vertical ones do. Adduction especially leads to changes; here, RMS showed a significant difference. CONCLUSIONS: Eye movements have a significant effect on wavefront profiles. The amount of aberration induced is generally very low. In individual cases, the numbers of aberrations induced by eye movements are in ranges reported to reduce the postoperative quality of vision when the ablation profile is taken into account.

[The influence of phenylephrine and tropicamide on higher order monochromatic aberrations]. / Einfluss von Phenylephrin und Tropicamid auf Aberrationen höherer Ordnung.

BACKGROUND: For wave-front guided corneal surgery, measuring higher order monochromatic aberrations in mydriasis is needed. However, a potential influence of mydriatic drugs on such aberrations could distort the ablation profile. METHOD: Wave-front analysis was carried out on 20 (tropicamide) and 19 (phenylephrine) eyes after dark adaptation, followed by measurement after the instillation of the mydriatics one after another. RESULTS: Phenylephrine had no significant influence on the wave-front; neither sphere nor RMS data differed from those taken after dark adaptation. After instilling tropicamide, significant changes in Z(2) (0) and, in parallel, also of the sphere were found. The RMS showed no significant difference, only the spherical aberration Z(4) (0) was reduced by an average of 0.035 microm. CONCLUSION: The wave-front changes individually through the mydriasis due to phenylephrine and tropicamide. In the case of tropicamide, the deviation is statistically significant. Therefore, abandonment of these mydriatics before refractive surgery can be recommended, as can the use physiological pupil dilatation. Because of its lower influence, phenylephrine should be the first choice if dimout effects no adequate mydriasis.

[Advanced glycation end products and pseudoexfoliation--correlation between clinical outcome and histological findings]. / Zur Bedeutung von Advanced Glycation End Products (AGE's) beim Pseudoexfoliationssyndrom (PXS)--Korrelation klinischer Ergebnisse mit immunhistologischen Untersuchungen an humanen Linsenkapseln.

BACKGROUND: Pseudoexfoliation syndrome (PXS) as a stress-induced microfibrillopathy often shows a prolonged postoperative course. Formation of advanced glycation end products (AGEs) might be also associated with an increased oxidative stress. This study investigated for the first time immunohistochemically lens capsules of PXS patients for the AGE carboxymethylysine (CML) and correlated the findings with the clinical outcome of the patients. METHODS: 55 patients (22 male, 33 female; mean age 73.9 +/- 14.1 years) with PXS and pseudoexfoliation glaucoma (PXG) after cataract extraction were included. All lens capsules could be investigated immunohistochemically for the AGE CML. Both preoperative biometric data as well as intra- and postoperative courses were included in the investigations, followed by a correlation analysis of the immunohistochemical findings. RESULTS: 29 PXS and 26 PXG patients with a mean axial length of 23.1 +/- 1.1 mm were explored. Both groups showed a postoperative decrease of intraocular pressure and a moderate increase of visual acuity. Intraoperatively, 6 zonulolyses occurred and postoperatively 11 patients showed problems like increases of intraocular pressure. Immunohistochemically, CML could be detected in most of the epithelial cells of the lens capsules but only in a small part of the pseudoexfoliation (PEX) fibrils. A correlation between positive CML immunoreaction and the clinical course was not detectable. CONCLUSIONS: Cataract extraction in patients with PEX glaucoma shows different specialities and risks. The AGE CML was detectable in human lens capsules. A direct correlation between clinical course and immunohistochemical reaction of the PEX fibrils could not be found. Overall, CML seems not to be a valuable predictive factor for the clinical course in patients with PXS and PXG.

Ex vivo stimulation of renal transport of the cytostatic drugs methotrexate, cisplatin, topotecan (Hycamtin) and raltitrexed (Tomudex) by dexamethasone, T3 and EGF in intact human and rat kidney tissue and in human renal cell carcinoma.

Previous experiments have shown that both in vivo and in vitro pre-treatment with various hormones increases the renal transport capacity for weak organic acids, such as PAH, in rats. The aim of the present study was to test whether or not accumulation of the anticancer drugs methotrexate (MTX), cisplatin (CP), raltitrexed (Tomudex) and topotecan (Hycamtin) can be increased in intact, healthy rat and human renal cortical slices and in human renal cell carcinoma (RCC). Intact, healthy human tissue was obtained from tumour bearing kidneys of patients suffering from RCC. Experiments were intended as a new approach to overcome so-called multidrug resistance. Kidney tissue slices were incubated for 24 h in William's medium E containing various concentrations of dexamethasone, T(3), or EGF. Thereafter slices were placed in anticancer drug containing Cross-Taggart medium and the drug uptake into kidney tissue was measured for 2 h. In intact rat and human renal tissue slices, the uptake of p-aminohippurate (PAH = reference substance) increased significantly after incubation in dexamethasone containing medium (134% and 156%, respectively). There were no stimulating effects of either T(3) or EGF on PAH accumulation. On the other hand, only the accumulation of MTX, but not of CP, raltitrexed or topotecan, was significantly enhanced after hormone pre-treatment both in intact renal tissue and in RCC. A stimulation of renal PAH accumulation can be performed ex vivo, as reported previously, both in intact rat and human renal cortical slices and in RCC. Discrepancies between the effects of dexamethasone and T(3) or EGF indicate different modes of action of these substances at the cellular level. Unfortunately, with the exception of MTX, the uptake of anticancer drugs can not be stimulated effectively ex vivo in human RCC tissue by the substances used. Evidently the transport of these anticancer drugs out of the kidney cells is more effective than their uptake.