Continuous expression of the homeobox gene Pax6 in the ageing human retina.

PURPOSE: In the past few years, the essential role of the homeobox gene Pax6 for eye development has been demonstrated unambiguously in a variety of species including humans. In humans, Pax6 mutations lead to a variety of ocular malformations of the anterior and posterior segment. However, little is known about PAX6 expression in the adult human retina. We have therefore investigated PAX6 levels and localization in the human retina at various ages. METHODS: Adult human eyes of various ages (17-79 years) were obtained from the Zurich Eye Bank. PAX6 expression levels and patterns were analysed by Western blot analysis of total retinal protein and by immunohistochemistry on paraffin sections, respectively. RESULTS: PAX6 expression in the retina was detected up to 79 years of donor age and was predominantly localized to the ganglion cell layer and the inner part of the inner nuclear layer. CONCLUSIONS: PAX6 remains distinctly expressed throughout the lifespan of the human retina suggesting a role for PAX6 in the retina after completion of eye morphogenesis.

[Reoperations after LASIK]. / Reoperationen nach LASIK.

BACKGROUND: Repeat operations after refractive surgery have increased in frequency during the past 10 years. The spectrum of the indications for repeat LASIK may have changed. METHODS: All cases of repeat operations after refractive surgery performed between May 1, 2004 and April 30, 2005 at the Institute of Refractive and Ophthalmic Surgery (IROC) were retrospectively investigated regarding indication for repeat surgery and visual and refractive results. The 1-month results were used to estimate the refractive and visual success rate. RESULTS: Of the 76 reoperations, 69 were performed as re-lifts, 3 eyes had new lamellae cut, and 3 cases needed keratoplasties. The reoperations took place 7.5 +/- 13 months after the primary operation (range 0.5 to 60 months). The most frequent indication was residual astigmatism of 0.5 D and more. Visual loss of more than 1 decimal line did not occur and unaided visual acuity increased from 0.64 to 1.05. No complications were reported, however, 3 eyes needed additional enhancement. CONCLUSIONS: Reoperations after LASIK performed as re-lifts appear to be effective and reasonably safe when using the technique described and respecting a residual stromal thickness of 280 microns.

[Nomograms for the improvement of refractive outcomes]. / Verbesserung der refraktiven Ergebnisse durch Nomogramme.

BACKGROUND: Nomograms are efficient tools to improve the predictability of refractive procedures by using statistical methods to analyze pre- and postoperative refractive data. The purpose of this work was to analyze the clinical relevance and limitations of nomograms in a case series. METHODS: Computer simulations based on the known unpredictability for refractive outcomes were performed for three different distribution functions of the preoperative refractions. In addition, the clinical applicability was investigated in three different cohorts that underwent laser in situ keratomileusis (LASIK). RESULTS: The use of individual nomograms significantly improves the predictability of the refractive outcome. However, theoretical investigation demonstrates that a homogeneous data distribution within cohorts is a key factor for predictable nomogram calculations. Outliers within the cohorts are not integrated into the nomogram calculation due to the mathematical model used. CONCLUSIONS: Nomograms are helpful for improving refractive outcomes. However, they are currently limited to approximately 90% within +/-0.5 D.

Dependence of wave front refraction on pupil size due to the presence of higher order aberrations.

PURPOSE: Propagation of light through the optical pathway within the eye can lead to a deformation of the wave front that might affect objective but also subjective refraction depending on pupil size. The aim of this study was to investigate the change in wave front refraction that is calculated on the basis of second order Zernike polynomials when varying the pupil size from 6 mm to 3 mm. The change was correlated with the amount of fourth and sixth order spherical aberration and fourth and sixth order astigmatism. METHODS: Wave front aberrations were measured in 130 eyes by means of a Tscherning wave front sensor at a pupil size of 6 mm. Wave front aberrations in terms of Zernike coefficients up to sixth order were approximated for 6 mm and 3 mm pupil size. The wave front refraction was calculated based on the second order Zernike coefficients for both pupil diameters. Resulting differences in wave front refraction (sphere or cylinder) due to the change in pupil size were correlated with the initial higher order aberrations determined for the 6.0 mm pupil by means of a linear regression (Spearman rank correlation coefficient). RESULTS: The correlation between the change in sphere and cylinder on one hand and the spherical aberration and higher order astigmatism on the other hand was found to be highly significant (p<0.001), with a correlation coefficient of R = 0.96 for sphere and R = 0.85 for cylinder. CONCLUSIONS: Calculating the wave front refraction on the basis of second order Zernike polynomials is plagued with the influence of the higher order aberration preexisting in the individual eye. This is one reason why this method does not represent precisely enough subjective refraction. Other methods that calculate the refraction based on wave front measurement independent from the pupil size should be established in the ophthalmic community.

[Preserving vision in the elderly: a survey to start a quality development program in general practice]. / Erhaltung des Sehvermögens im Alter: Eine Patienten- und Hausarztbefragung zur Einleitung eines Qualitätsentwicklungsprojektes in der Hausarztpraxis.

The study examined the rate of patients, who do not follow recommendations for routine screening, do not visit physicians for eye-symptoms and when suffering from diabetes or glaucoma do not adhere to follow-up. To what extent can primary care physicians impact on these deficits of ophthalmologic care? 4918 consecutive, > or = 40 old patients of 107 primary care physicians of 9 networks participated. Of these patients 15% had never, 43% not within the last 3 years, consulted an ophthalmologist. 16% were diabetics, 7% had glaucoma and 46% had observed subjective eye symptoms. A quarter of these patients turn to their primary care physician, when having eye problems. Primary care physicians do not frequently suggest routine ophthalmologic controls nor do they use diagnostic tools like the Amsler-grid or the Swinging-Flash-Light Test.

Why study rod cell death in retinal degenerations and how?

Age-related macular degeneration (AMD) is a main causes of severe visual impairment in the elderly in industrialized countries. The pathogenesis of this complex diseases is largely unknown, even though clinical characteristics and histopathology are well described. Because several aging changes are identical to those observed in AMD, there appears to exist an unknown switch mechanism from normal ageing to disease. Recent anatomical studies using elegant innovative techniques reveal that there is a 30% rod loss in normal ageing, which is increased in early AMD. Those and other observations by Curcio and co-workers indicate that early rod loss is an important denominator of AMD (Curcio CA. Eye 2001; 15:376). As in retinitis pigmentosa (RP), rods appear to die by apoptosis. Thus it seems mandatory to study the regulation of rod cell death in animal models to unravel possible mechanisms of rod loss in AMD. Our laboratory investigates signal transduction pathways and gene regulation of rod death in our model of light-induced apoptosis. The transcription factor AP1 is essential, whereas other classical pro- and antiapoptotic genes appear to be less important in our model system. Caspase-1 gene expression is distinctly upregulated after light exposure and there are several factors which completely protect against light-induced cell death, such as the anesthetic halothane, dexamethasone and the absence of bleachable rhodopsin during light exposure. A fast rhodopsin regeneration rate increased damage susceptibility. Our data indicate that rhodopsin is essential for the initiation of light-induced rod loss. Following photon absorption, there may be the generation of photochemically active molecules wich then induce the apoptotic death cascade.

Traumatic rupture of the globe caused by cow horns.

PURPOSE: We investigated the epidemiology, clinical findings and functional outcome of open-globe injuries caused by cow horns over a 50-year period in eastern Switzerland. METHODS: We retrospectively evaluated the files of cases with ruptures of the globe caused by cow horns between 1950 and 1999. RESULTS: We found 59 cases with ruptures of the globe by cow horns, accounting for 5% of all open-globe injuries. The incidence of these accidents did not change during the observation period. Twenty-two eyes (37%) were enucleated. Only 7 eyes (12%) retained a vision of > or = 0.1. Between 1950 and 1989 only 2/43 eyes (5%) reached a vision of > or = 0.1. In the 1990's, with the introduction of vitreous surgery 5/16 eyes (31%) had a vision of > or = 0.1. Four patients (7%) had blinding eye disease in the partner eye, and three (5%) had a second open-globe trauma. CONCLUSIONS: In rural regions, with cattle breeding, open-globe injuries by cow horns are relatively common and the frequency is still the same as 50 years ago. The visual prognosis of these eyes is still guarded, but functional results have improved with the introduction of vitreous surgery. Patients who have had a rupture of the globe appear to have an increased risk for partner eye trauma. Therefore, all efforts are justified to preserve even limited vision in severely injured eyes.