Biomedical subjects

B Csákány

Publications and source records attributed to B Csákány.

6 recordsLinked to original sources

PubMed2003

Changes in tear protein pattern after photorefractive keratectomy.

PURPOSE: Changes in tear protein composition of patients who underwent photorefractive keratectomy (PRK) were analyzed. METHODS: Tear samples were obtained from 23 eyes of 23 patients immediately before PRK and on the fourth postoperative day with glass capillaries. Tear proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Digital image analysis and evaluation of the densitometric data of the electrophoretic separations were done with BioDoc-Analyze. RESULTS: Analysis of discriminance found a significant difference in the protein patterns (p < 0.001). This type of analysis of the electrophoretic densitographs uses all peak information simultaneously. A significant decrease (p < 0.005) in three of the main protein peaks--lactoferrin, immunoglobulin A heavy chain, and lysozyme--was also found after PRK. CONCLUSIONS: Excimer laser ablation of the cornea has an acute effect on lacrimal gland protein secretion. Changes in tear composition may lead to feelings of dryness and to a decrease in tear film stability postoperatively.

Adult↗

PubMed2001

Corneal topography changes after a 15 second pause in blinking.

PURPOSE: To examine the effect of a short pause in blinking on the quantitative topographic parameters of the corneal surface. SETTING: Refractive corneal surgery unit of a university eye hospital. METHODS: Using a TMS-1 instrument (Computed Anatomy, Inc.), corneal topographic parameters were measured 5 and 15 seconds after a complete blink in 12 healthy subjects. The main outcome measures were changes in the surface regularity index (SRI) and the surface asymmetry index (SAI). RESULTS: During the pause in blinking, the mean SRI value increased from 0.18 +/- 0.19 (SD) to 0.30 +/- 0.19 (P <.02) and the SAI from 0.21 +/- 0.08 to 0.24 +/- 0.10 (P =.079, not statistically significant). There were no significant changes in the values for potential visual acuity, corneal refractive power, or astigmatism. CONCLUSION: The results indicated a significant change in corneal topography during even a short pause in blinking. In follow-up studies using corneal topography, all measurements should be done at a fixed time after a complete blink.

Adult↗

PubMed1996

[Examination of subepithelial scar formation after photorefractive keratectomy with the ultrasound biomicroscope].

BACKGROUND: The subepithelial haze and the concomittant refractive regression are the most important complications of photorefractive keratectomies (PRK). The authors examined the subepithelial haze characteristics by ultrasound biomicroscopy (UBM). MATERIALS AND METHODS: Twenty previously photokeratectomized myopic eyes, which showed a certain level of subepithelial scarring have been examined (age: 34.22 +/- 3.57 years, 12 women, 8 men). The range of PRK treatments varied between -4.0 D and -12.0 D. The subepithelial haze graded according to Hanna et al, between 1.0 and 4.0. The UBM examinations were carried out between 1-3 months following PRK with the 50-80 MHz transducer of a Model 840 Zeiss-Humphrey Ultrasound Biomicroscope. RESULTS: The severity of subepithelial haze correlated with the previous photoablation depth. Up till haze graded 2.0 according to Hanna et al. UBM showed loss of Bowman membrane and a slight thinning of the central cornea. Between grade 2.0 and 3.0 the reflectivity of anterior stroma increased, above grade 3.0 a hyperreflective 1/3 anterior stroma with irregular borders were observed. CONCLUSION: Haze phenomen graded below 2.0 is not observable with UBM. Haze, graded more than 2.0 caused an increase of anterior stormal reflectivity. In more serious cases the 1/3 of the anterior stroma might be affected. The UBM-method with a 50-80 MHz probe is suitable to document and follow the serious haze phenomen after photoablations.

Adult↗

PubMed1991

Effect of lanthanum-induced blockade of calcium channels on nerve regeneration.

Systemic lanthanum chloride administration results in impeded myelin formation of regenerating peripheral axons and in marked decrease of regenerative elongation of dorsal root axons within the upper dorsal horn of the spinal cord. It is assumed that the inhibitory action of lanthanum ions is based on a competitive antagonism with calcium ions, insofar as lanthanum ions induce blockade of calcium channels in axonal growth cones. Consequently, motility: of axonal filopodia emanating from axonal growth cones, instrumental in longitudinal growth of regenerating central axons, is inhibited by lanthanum ions. Supposedly, a similar inhibitory action upon rotational movement of Schwann cells results in the retarded myelinization of peripheral axons.

Animals↗

PubMedDate not supplied

Ultrasound biomicroscopic morphometry of the anterior eye segment before and after one drop of pilocarpine.

PURPOSE: To measure anterior eye-segment morphometric data using ultrasound biomicroscopy. This is a new high-frequency, high-resolution ultrasound method enabling the visualisation of the anterior segment of the living eye with magnification similar to a light microscope. METHODS: Thirteen morphometric parameters of the anterior eye segment were measured before and after the application of one drop of pilocarpine in 10 eyes of 5 persons, using a Zeiss-Humphrey Ultrasound Biomicroscope at a frequency of 50 MHz. In each session, 3 morphometric parameters in the central images (corneal thickness, anterior chamber depth, pupillary diameter) were measured 4 times, and 10 parameters in the radial images (scleral thickness, angle-opening distance, trabecular-iris angle, trabecular-ciliary process distance [TCPD], iris thickness, 1, 2 and 3, iris-ciliary process distance, iris-lens contact distance [ILCD], iris elevation) were measured on the 3, 6 and 9 o'clock meridians three times each. RESULTS: Statistically significant changes were noted in the following parameters: pupillary diameter, iris thickness 1 and 2, and TCPD were decreased, while ILCD was increased after pilocarpine. Wide chamber angles showed a tendency to become narrower and narrow ones to become wider after pilocarpine. CONCLUSION: One drop of pilocarpine caused significant changes in the anterior eye segment morphology. Not only the pupillary diameter decreased but iris thickness and trabecular-ciliary process distance were also decreased simultaneously. At the same time the contact surface between the lens and iris increased significantly. Ultrasound biomicroscopy gives new morphometric image information about the anterior eye segment which is not available using conventional gonioscopy or ophthalmic echography.

Administration, Topical↗

PubMedDate not supplied

Reproducibility of keratometric measurements decreases with time after blinking.

PURPOSE: The reproducibility of keratometry measurements was investigated in relation to the elapsed time after blinking. METHODS: Thirty ophthalmologically healthy subjects were examined, using a standard corneal topographic instrument (17 women, 13 men, age 25.7+/-5.6 years). Photographs were taken in series of four: at 5, 15, 30, and 60 seconds after a complete blink. The series was repeated three times in each individual. The main outcome measures were the mean values, the standard deviation, and the reproducibility error of the simulated keratometric values (K1, K2), the surface regularity index (SRI), and the surface asymmetry index (SAI). RESULTS: The mean of K 1 and K 2 values did not change (p=0.684 and p=0.982); however, the measurement error increased significantly for K1 (p=0.007) and for K2 (p=0.038). The mean values of SRI changed significantly (p=0.034) during the 1-minute pause in blinking together with a non-significant change in the standard deviation (p=0.106), without elevation of the measurement error (p=0.619). The elevation of SAI with time was not significant (p=0.093). CONCLUSIONS: The break-up phenomenon of the tear film at the ocular surface induces significant deterioration of the reliability of keratometric measurements on prolonged gaze without blinking. The created error can exceed 0.6 D, which is unacceptably high in practice. Therefore care should be taken to avoid such circumstances during the examination.

Adult↗