Christian Meltendorf

Corneal trephination with the femtosecond laser.

Purpose: To evaluate the feasibility and cut quality of corneal trephination in human donor corneal tissue with the femtosecond laser. Methods: Twelve human corneoscleral discs were inserted in an artificial anterior chamber. After corneal thickness measurement and tonometry, the cornea was mounted on a femtosecond laser (FEMTEC; 20/10 Perfect Vision, Heidelberg, Germany) through a contact lens (patient interface). Trephination was performed with diameters of 7.0, 7.5, 8.0, and 8.5 mm in 3 corneas each. The corneal button was removed from the corneoscleral disc in 2 of the 3 corneas in each case. The cut was not manipulated in the remaining corneas to enable histologic detection of possible tissue bridges. The cut edges were macroscopically and light-microscopically examined for quality. Results: Corneal buttons and corneoscleral discs could be separated by blunt dissection in all cases. Tissue bridges were more common in thicker edematous corneas than in thinner ones. Both the macro- and microscopic examination disclosed smooth rectilinear cut margins with a perpendicular cut edge. Conclusion: This feasibility study shows that the femtosecond laser enables sufficient trephination of human donor corneas.

A system for the automatic estimation of morphometric parameters of corneal endothelium in alizarine red stained images

Background/aims A computer program for the automatic estimation of endothelium morphometric parameters (cell density, pleomorphism, polymegethism) in alizarine red-stained images is presented and evaluated. Methods Images of corneal endothelium from 30 porcine eyes stained with alizarine red were acquired with an optical microscope and saved as grey-level digital images. Each image was first pre-processed for luminosity correction and contrast enhancement. An artificial neural network was used to classify all pixels as cell contour or cell body pixels. The segmented cell contours were then used to obtain estimates of morphometric parameters. The central area was assessed and the mean area per cornea was 0.54±0.07 mm2. The whole system was implemented as a computer program using the Matlab language. Estimated parameters were compared with the corresponding values derived from manual contour detection on the same images used for the automatic estimation. Results For the 30 images in our dataset, the mean differences for automatic versus manual parameters were −12±52 (range −103 to +145) cells/mm2 for density, 0.5±2.6% (range −5.6 to +5.6%) for pleomorphism and −0.7±1.9% (range −4.1 to +2.8%) for polymegethism. Conclusion The evaluation of the automatic system on 30 images from porcine eyes confirmed its ability to estimate reliably morphometric parameters with respect to parameter values derived by manual analysis.

Correlation between clinical in vivo confocal microscopic and ex vivo histopathologic findings of Salzmann nodular degeneration.

Purpose: To report clinical, in vivo confocal microscopy and ex vivo histopathologic findings of Salzmann nodular degeneration (SND). Methods: A 48-year-old woman with symptoms of ocular irritation and decreased visual acuity caused by SND in both eyes was treated by corneal scraping and phototherapeutic keratectomy (PTK). Slit-lamp biomicroscopy, in vivo confocal microscopy, ex vivo light microscopy, immunohistology, and corneal topography were performed. Results: In vivo confocal microscopy showed an irregular network of highly reflective structures representing activated keratocytes, which could be seen by light microscopy and characterized immunohistologically as myofibroblasts. Unstructured areas with increased reflectivity correlated with irregularly arranged collagen fibers and hyaline deposits in the nodulus. Epithelial cells in vivo appeared atypically shaped and elongated. These observations were consistent with decreased thickness of the epithelium over the nodules showed by histopathology. Treatment led to a dramatic reduction of hyperopia. Two months after surgery, uncorrected visual acuity (UCVA) in the right eye was 20/32 and 20/20 with a refraction of −0.75 -0.75/0°. UCVA in the left eye was 20/40 and 20/20 with a refraction of +0.50 −1.75/165°. Corneal topography showed regular astigmatism. Conclusion: In vivo confocal microscopy confirmed the clinicopathologic findings of Salzmanns nodular degeneration. Observations by in vivo confocal microscopy were consistent with the histopathologic descriptions of SND.

Arbeitsbedingungen des wissenschaftlichen Nachwuchses in der Augenheilkunde

PURPOSE By evaluating the current working conditions of young ophthalmology researchers in Germany, potential deficits should be highlighted to create a greater transparency. PATIENTS AND METHODS Within the time period between October 2008 and March 2009 all residents and junior researchers at university eye hospitals and teaching hospitals were invited to participate in an open online survey to retrieve validated data on four different topics. RESULTS A total of 187 validated residents filled out the questionnaire consisting of 48 items. The mean age of the 84 women and 77 men was 32±4 years and 48% of the physicians reported exceeding the normal working hours (by law) 4-5 times per week. Of the respondents 76% ruled out ever being supported in their research activities by a temporary release from clinical work. Nevertheless, several indices indicated enthusiastic career aspirations and research activities. The career success scale was greater than 5 in 70 (37%) of the participants (mean: 4.5). An adequate access to ophthalmologic online journals was indicated only by 59% of the people surveyed and 45% of scientists required additional support by English native speakers when writing a scientific manuscript. All physicians interviewed would decide in favor of ophthalmology again when asked which discipline would be chosen and 28% of the residents would not apply for a job at the same institution again. The atmosphere, access to surgical training and the quality of teaching were specified as the most important factors in the career decision in favor of a certain university. CONCLUSION Some deficits of the training and working conditions could be clearly identified in the view of ophthalmology residents. Facing the unbroken high attractiveness of clinical disciplines, the provided insights can support further training programs and research incentives to improve the scientific output and ophthalmologic research in the long term.

Vergrößerter blinder Fleck

Fletcher et al. [1] beschrieben das „Acute Idiopathic Blind Spot Enlargement Syndrome“ erstmals 1988 als Symptomkomplex mit plotzlich auftretendem, monokularem Gesichtsfelddefekt im Bereich des blinden Flecks ohne Papillenschwellung bei regelrechten Befunden bezuglich Visus, Farbwahrnehmung, Pupillenreaktion und Fundusbefund. Das Syndrom betrifft vor allem Frauen im mittleren Lebensalter [2, 3]. Die Atiologie ist bisher ungeklart. Es zeigen sich jedoch Parallelen zu anderen Krankheitsbildern wie dem „Multiple Evanescent White Dot Syndrome“, das eine entzundliche Genese vermuten lasst [7]. Shinoda et al. [4] zeigten, dass eine morphologische Storung im Bereich der Ausensegmente der Photorezeptoren vorliegt.