Comparability of input parameters in the German Retina.net ROP registry and the EU-ROP registry - An exemplary comparison between 2011 and 2021

PURPOSE

The German Retina.net ROP registry and its Europe-wide successor, the EU-ROP registry, collect data from patients treated for ROP. This analysis compares input parameters of these two registries to establish a procedure for joint analyses of different registry data using exemplary datasets from the two registries.

METHODS

Exemplary datasets from the two databases over a 1-year period each (German Retina.net ROP Registry, 2011, 22 infants; EU-ROP Registry, 2021, 44 infants) were compared. The parameters documented in the two databases were aligned and analysed regarding demographic parameters, treatment modalities, complications within first 24 h and retreatments.

RESULTS

The current analysis showed that data can be aligned for joint analyses with some adjustments within the data structure. The registry with more detailed data collection (EU-ROP) needs to be reduced regarding granularity in order to align the different registries, as the registry with lower granularity determines the level of analyses that can be performed in a comparative approach. In the exemplary datasets, we observed that the overall most common ROP severity in both registries was zone II, 3+ (2011: 70.5%; 2021: 65%), with decreasing numbers of clock hours showing preretinal neovascularisations (2011: 10-12 clock hours in 29% of cases, 2021: 4-6 clock hours in 38%). The most prevalent treatment method was laser coagulation in 2011 (75%) and anti-VEGF therapy in 2021 (86.1%). Within the anti-VEGF group, all patients were treated with bevacizumab in 2011 and with ranibizumab in 2021. Retreatment rates were comparable in 2011 and 2021.

CONCLUSION

Data from two different ROP registries can be aligned and jointly analysed. The analysis reveals a paradigm shift in treatment modalities, from predominantly laser to anti-VEGF, and within the anti-VEGF group from bevacizumab to ranibizumab in Germany. In addition, there was a trend towards earlier treatment in 2021.

Large magnetoresistance and quantum oscillations in Sn0.05Pb0.95Te

We have synthesized high-quality single crystals of Sn_xPb_1-xTe and carried out detailed studies of the magnetotransport properties of one of the samples, Sn_0.05Pb_0.95Te. Longitudinal magnetoresistance increases almost linearly with increasing applied field (H) and reaches ∼310% atH= 13 T. At higher fields, both longitudinal and Hall resistance show clear Shubnikov de Haas oscillations. The oscillations are smooth and periodic, and there exists only one frequency,f_α∼ 57 T. However, an additional frequency,f_β∼ 69 T, appears as the angle between the field direction and the normal to the sample surface (θ) is increased. Bothf_αandf_βexhibitθ-dependence;f_αdecreases whereasf_βincreases gradually with increasingθ. The presence of two frequencies in Sn_0.05Pb_0.95Te indicates that there exist two Fermi surface pockets (αandβpockets). We have constructed the Landau-level fan plot and determined the Berry phase (δ) for theαpocket to beδ∼ 0.1. Thisδvalue is very close to the expected value of 0 for a topologically trivial system.

[Chorioretinal atrophy in pediatric cerebral folate deficiency-a preventable disease?]

Cerebral folate deficiency (CFD) results in neurological alterations and a massive degeneration of the choroid/retina if left untreated, which limit the visual field and visual acuity. This article reports the case of a female patient with CFD, who developed autistic personal characteristics prior to reaching school age and first started to speak at the age of 3 years. At the age of 6 years she was presented because of unclear reduced visual acuity in the right eye. At that time mild bilateral peripheral chorioretinal atrophy was present, which subsequently became more pronounced. Additionally, a centrally emphasized chorioretinal atrophy further developed. Visual acuity of both eyes progressively deteriorated until stagnating at 0.1 at the age of 14 years. The causal assignment of the findings of the patient was not possible for many years. Choroideremia was excluded by molecular genetic testing (CHM gene with no mutations) and gyrate atrophy was ruled out by a normal ornithine level. The existence of a mitochondrial disease was almost completely excluded by exome sequencing. After the onset of further nonocular symptoms, e.g. neuromuscular disorders, electroencephalograph (EEG) alterations and autistic disorder, intensified laboratory diagnostics were performed in the treating pediatric hospital. Finally, an extremely low level of the folic acid metabolite 5‑methyltetrahydrofolate was detected in the cerebrospinal fluid (CSF) leading to the diagnosis of CFD. High-dose substitution treatment with folic acid was subsequently initiated. After excluding the presence of a pathogenic mutation of the FOLR1 gene for the cerebral folate receptor 1, a high titer blocking autoantibody against cerebral folate receptor 1 was detected as the cause.

Discrimination between pathogenic and non-pathogenic E. coli strains by means of Raman microspectroscopy

Bacteria can be harmless commensals, beneficial probiotics, or harmful pathogens. Therefore, mankind is challenged to detect and identify bacteria in order to prevent or treat bacterial infections. Examples are identification of species for treatment of infection in clinics and E. coli cell counting for water quality monitoring. Finally, in some instances, the pathogenicity of a species is of interest. The main strategies to investigate pathogenicity are detection of target genes which encode virulence factors. Another strategy could be based on phenotypic identification. Raman spectroscopy is a promising phenotypic method, which offers high sensitivities and specificities for the identification of bacteria species. In this study, we evaluated whether Raman microspectroscopy could be used to determine the pathogenicity of E. coli strains. We used Raman spectra of seven non-pathogenic and seven pathogenic E. coli strains to train a PCA-SVM model. Then, the obtained model was tested by identifying the pathogenicity of three additional E. coli strains. The pathogenicity of these three strains could be correctly identified with a mean sensitivity of 77%, which is suitable for a fast screening of pathogenicity of single bacterial cells.

Isolation matters-processing blood for Raman microspectroscopic identification of bacteria

Bacteremia with its high mortality is a frequent case in clinical health care. Further, bacteremia includes the considerable risk of progressing to a sepsis. Even in case of survival, sepsis still entails diminished quality of life for the survivors and high indirect cost for the society. The crucial factor in sepsis is time. Therefore, timely description of adequate antibiotics is vital to reduce mortality and improve quality of life after survival. Despite that, the current gold standard of clinical bacteria diagnostic is based on cultivation of bacteria, which requires an average of 13-h cultivation. Consequently, there is a necessity for culture free identification methods without sacrificing the range of bacteria strains which can be identified. Raman microspectroscopy in general requires only single bacteria cells and has proven to offer high identification accuracies. However, the prerequisite for Raman microspectroscopy is a suitable isolation strategy to obtain single unharmed bacteria cells free from matrix. Moreover, in blood, bacteria are outnumbered by billions of blood cells. In this study, we present an isolation strategy to recover single bacteria cells from blood and evaluate their suitability for Raman microspectroscopic identification. Graphical abstract.

Toward genome editing in X-linked RP-development of a mouse model with specific treatment relevant features

Genome editing represents a powerful tool to treat inherited disorders. Highly specific endonucleases induce a DNA double strand break near the mutant site, which is subsequently repaired by cellular DNA repair mechanisms that involve the presence of a wild type template DNA. In vivo applications of this strategy are still rare, in part due to the absence of appropriate animal models carrying human disease mutations and knowledge of the efficient targeting of endonucleases. Here we report the generation and characterization of a new mouse model for X-linked retinitis pigmentosa (XLRP) carrying a point mutation in the mutational hotspot exon ORF15 of the RPGR gene as well as a recognition site for the homing endonuclease I-SceI. Presence of the genomic modifications was verified at the RNA and protein levels. The mutant protein was observed at low levels. Optical coherence tomography studies revealed a slowly progressive retinal degeneration with photoreceptor loss starting at 9 months of age, paralleling the onset of functional deficits as seen in the electroretinogram. Early changes to the outer retinal bands can be used as biomarker during treatment applications. We further show for the first time efficient targeting using the I-SceI enzyme at the genomic locus in a proof of concept in photoreceptors following adeno-associated virus mediated gene transfer in vivo. Taken together, our studies not only provide a human-XLRP disease model but also act as a platform to design genome editing technology for retinal degenerative diseases using the currently available endonucleases.

Raman spectroscopic identification of Mycobacterium tuberculosis

In this study, Raman microspectroscopy has been utilized to identify mycobacteria to the species level. Because of the slow growth of mycobacteria, the per se cultivation-independent Raman microspectroscopy emerges as a perfect tool for a rapid on-the-spot mycobacterial diagnostic test. Special focus was laid upon the identification of Mycobacterium tuberculosis complex (MTC) strains, as the main causative agent of pulmonary tuberculosis worldwide, and the differentiation between pathogenic and commensal nontuberculous mycobacteria (NTM). Overall the proposed model considers 26 different mycobacteria species as well as antibiotic susceptible and resistant strains. More than 8800 Raman spectra of single bacterial cells constituted a spectral library, which was the foundation for a two-level classification system including three support vector machines. Our model allowed the discrimination of MTC samples in an independent validation dataset with an accuracy of 94% and could serve as a basis to further improve Raman microscopy as a first-line diagnostic point-of-care tool for the confirmation of tuberculosis disease.

[Genotype-Phenotype Correlations in Patients with CRB1 Mutations]

Background Mutations in the CRB1 gene were identified in patients with early-onset severe retinal dystrophy (EOSRD), childhood-onset and juvenile-onset rod-cone dystrophy. This study describes the phenotypic spectrum of disease-causing CRB1-mutations in the first two decades of life. Materials and Methods Eight patients, aged three months to 20 years, underwent a full comprehensive ophthalmological examination including best corrected visual acuity testing (BCVA), color vision testing, funduscopy, spectral-domain optical coherence tomography (SD-OCT), and fundus autofluorescence (FAF) recording. Automated and manual retinal layer segmentation of SD-OCT recordings was performed using DIOCTA software. A full-field electroretinography (ffERG, ISCEV Standard) and visual fields were performed in cooperative patients. Results Five patients carried mutations causing a loss of the corresponding gene product (splice-mutation, nonsense-mutation, frame-shifting mutation). These patients presented with generally reduced vision in the first months of life that never exceeded 0.04 during the observational period. The sixth patient carried a homozygous missense mutation and reached maximal BCVA 0.05 at the age of 6 years. Two further patients, carrying at least one hypomorphic missense-mutation, presented with better preserved visual function with up to 0.5 at the age of 20 years. The recorded ffERG was below threshold in the majority of patients. Visual fields were severely restricted. The photoreceptor layers were significantly reduced in SD-OCT whenever stratification of retinal layers was possible. The inner nuclear layer thickness increased with progressing retinal degeneration. A-Scan analysis revealed better preservation of the retinal stratification in patients with missense mutations. Conclusions Patients with CRB1-mutations presented with a severe phenotype with severely reduced visual acuity from birth. Missense mutations with predicted residual function of the gene product were associated with moderate expression of the disease. Severe and progressive restriction of visual fields occurred in the first decade of life. The reduced retinal stratification indicates a general loss of structural integrity of the retinal layers.

[Handheld Optical Coherence Tomography in Paediatric Ophthalmology: Experience of the Department of Ophthalmology in Giessen]

Introduction: Optical coherence tomography is an important tool for the imaging and analysis of retinal structures. The usability of conventional table-top devices is limited in children. We report on our experiences with a handheld Spectral Domain Optical Coherence Tomography (HH-SD-OCT, Bioptigen™) in infants and young children in our daily practice. Methods: Between October 2014 and April 2016, we investigated 259 patients. Indications and diagnoses were assessed. Individual examples are shown to demonstrate the advantages and disadvantages of the novel technique. Results: It was possible to examine 259 children of at least 7 weeks of age (median: 1.59 years; ± 1.32 SD) with a mean investigation time of 18.3 minutes (± 8.3 SD). The most frequent indication was retinal assessment in prematures (32.8 %). Nystagmus, retinal dystrophies, reduced visual acuity and albinism amounted to additional 37.4 % of all indications. Conclusions: Handheld OCT is a beneficial complement for diagnosis of diseases in paediatric ophthalmology. As a complement to established methods like wide-field fundus photography, HH-SD-OCT allows the physician to assess and follow-up new objective structural information. As the Bioptigen does not have an eye tracker, it is challenging to orient the scan in the posterior retinal pole, in particular in case of instable fixation. This complicates follow-up investigations, which can only be performed with additional high programming and analysis effort.

[Indication and Results of the Anderson Procedure]

The major goal of extraocular muscle surgery for nystagmus is to reduce the abnormal head turn (AHT) which is caused by an eccentric null zone of the nystagmus. Shifting the null zone to the primary gaze position will eliminate the AHT. The Kestenbaum procedure consists of bilateral recession of the yoke muscles opposite to the AHT, combined with bilateral resection or plication of their antagonists. The Anderson procedure is confined to bilateral recession of the yoke muscles and is therefore less invasive. We report on our experience with the Anderson procedure. Patients and Methods: From September 2013 to June 2015, we performed the Anderson procedure in 11 consecutive orthotropic patients with infantile idiopathic or sensory defect nystagmus. Patients responsive to convergence inducing prisms who could benefit from artificial divergence surgery were excluded. Results: Medians and ranges (minimum-maximum) were: Age 7 years (4-30); binocular BCVA 0.5 (0.05-1.0); AHT 30° (20-40); equal recessions on the horizontal yoke muscles opposite to the AHT of 12 mm (10-17), in one case using bovine pericardium grafts. Three (3-6) months post surgery, the AHT was reduced to 7° (0-20). First step success rates, defined by residual AHT ≤ 10° and ≤ 15°, were 73 % (95 % CI 39-93 %) and 82 % (95 % CI 48-97 %). No over-correction or other adverse effects were observed. Two patients later received augmenting surgery. One patient with pre-existing exophoria later required strabismus surgery for exotropia. Conclusion: The AHT can be significantly reduced or completely corrected by the Anderson procedure. Recessions of at least 10 mm on both yoke muscles were performed. The success rates equaled success rates of augmented Kestenbaum surgery. Compared to the latter, the Anderson procedure is less invasive. It is followed by a shorter healing process. It is a vessel sparing method - an advantage for potential future surgery.

[Albinism and the Range of Fundus Hypopigmentation, Macular Hypoplasia, and Nystagmus]

From the ophthalmological view, albinism is a disorder of reduced pigmentation of the retinal and irdial pigment epithelium and the iris and choroid stroma. The reduced pigmentation is accompanied by morphological changes in the retina and the optic nerve. The functional relationship of these morphological changes is not yet well understood. This review summarises the genetic causes of reduced pigment synthesis and impaired pigment distribution, and discusses the variability of expression of albinism symptoms, in the light of other disorders affecting retinal development.

[Treatment Options for Basal Cell Carcinomas of the Medial Canthus]

Basal cell carcinoma is the most common skin cancer of the eyelid. It most frequently occurs on the lower eyelid and the medial canthus. Although metastases appear only very rarely, basal cell carcinoma is locally destructive if left untreated. Nowadays several surgical and nonsurgical treatments can be used to remove or destroy basal cell carcinomas. The selection of optimal treatment depends on the initial individual situation as well as the age and the general condition of the patient. The "gold standard" method for the treatment of basal cell carcinomas is surgical removal with subsequent histological examination. Because of the complex anatomical characteristics of the medial canthus and the lateral nasal root region, basal cell carcinomas of this area present great challenges for any treatment method. These characteristics also explain the higher rates of incomplete removal and greater risk of recurrence, with in depth extension of the tumor. Additionally, surgical removal of the tumor from the medial canthus area often results in extended tissue defects. The plastic covering of these defects can be achieved by various reconstruction procedures.

Correlation of central visual function and ROP risk factors in prematures with and without acute ROP at the age of 6-13 years: the Giessen long-term ROP study

AIM

To correlate light increment sensitivity (LIS) and visual acuity (VA) with birth weight (BW), gestational age (GA) and stage of acute retinopathy of prematurity (ROP) (STG) in premature children at school age.

METHODS

180 children (150 former prematures and 30 age-matched term-born children) were enrolled at age 6-13 years. Former prematures were categorised by the results of the initial ROP screening based on digital wide-field fundus imaging: absence of ROP (n=100) and spontaneously resolved ROP (n=50). The latter group was further subdivided according to their STG (Stg 1; Stg 2; Stg 3). Both groups were categorised into sectors by BW (<1000 g; 1000-1500 g; >1500 g), and GA (≤28 weeks; >28<32 weeks; ≥32 weeks). VA was assessed with Early Treatment of Diabetic Retinopathy Study letters, LIS was measured at 0°, 2.8° and 8° in the visual field (Microperimeter MP1, Nidek Technologies), and spherical equivalent refraction assessed with a Nidek autorefractor (Nidek, Italy).

RESULTS

Central and pericentral LIS (0° and 2.8°) and VA were significantly lower in all groups and sectors compared with term-born controls except for BW >1500 g for LIS and GA >28 to <32 W for VA. No significant differences were found for LIS at 8° in all groups. No correlation was found between LIS and VA on an individual basis.

CONCLUSIONS

Low BW, GA and increasing severity of spontaneously resolving ROP were associated with significantly decreased central visual function. In addition to VA, LIS measurement further describes foveal function and is a unique parameter to assess parafoveal function.

[Recruitment of Suitable Families to Identify Causative Genes in Hereditary Strabismus]

PURPOSE

The cause and origin of primary strabismus are not well understood. It is thought that there is multifactorial genetic inheritance. Only linkage analysis has been applied to study the genetic causes and correlations. The objective of this study was the compilation and statistical evaluation of a useful cohort of families for linkage analysis.

METHODS

The archives of the Department of Ophthalmology of the Justus-Liebig-University Gießen were used as a database for this study. Medical records of visits between January 2001 and July 2008 were analysed. Evaluation was based on the medical history form. The data set was scanned for index families in which at least two members had any form of primary strabismus. Patients were classified according to their type of primary strabismus. Families who were most suitable for linkage analysis were approached. A disease specific questionnaire was developed to complete the data.

RESULTS

Between January 2001 and July 2008, 20,813 patients affected by primary strabismus were treated. The data set contained 2380 patients with a positive family history of primary strabismus. The majority presented with esotropia (67 %), followed by exotropia (21 %). In most cases (80 %), two family members were affected and the child-parent relationship contributed the largest group, including 948 cases (40 %). Affected siblings were found in 397 families (17 %). Three affected patients were identified in 432 (18 %) families. In these, the relationship parent-child-sibling occurred most frequently, with 143 cases (6 %). A positive family history of at least four related patients was found in 46 families (2 %). Forty-two families were particularly suitable for linkage analysis. Seventeen of the 42 families answered a questionnaire aimed at improving the data set. Three families finally participated in ophthalmic examinations and agreed to blood sampling to perform linkage analysis.

CONCLUSION

The fraction of families with strabismus patients in more than two consecutive generations was extremely low. If these families are included in any study, this should be coupled to treatment to improve compliance.

[Manifestation of bilateral choroidal osteoma in childhood. Progressive myopia due to staphyloma posticum]

BACKGROUND

Case report of a 6-year-old boy with bilateral choroidal osteoma.

CASE REPORT

The patient was followed up for the next 6 years and during this period bilateral tumor progression was observed. In one eye a staphyloma posticum developed in the area of the osteoma which led to secondary anisometric myopia.

CONCLUSION

If undetected, this rare complication can lead to anisometric amblyopia; therefore, repeated cycloplegic refractometry is advisable in children with choroidal osteoma.

General theory of frictional heating with application to rubber friction

The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures which may strongly effect friction and wear. This is the case for rubber sliding on road surfaces at speeds above 1 mm s(-1). We derive equations which describe the frictional heating for solids with arbitrary thermal properties. The theory is applied to rubber friction on road surfaces and we take into account that the frictional energy is partly produced inside the rubber due to the internal friction of rubber and in a thin (nanometer) interfacial layer at the rubber-road contact region. The heat transfer between the rubber and the road surface is described by a heat transfer coefficient which depends on the sliding speed. Numerical results are presented and compared to experimental data. We find that frictional heating results in a kinetic friction force which depends on the orientation of the sliding block, thus violating one of the two basic Leonardo da Vinci 'laws' of friction.

Role of hydrophobicity on interfacial fluid flow: theory and some applications

The fluid flow through a seal interface depends on the percolating non-contact channels morphology, size and length, and on the interfacial surface energies. In particular, hydrophobic interfaces may expel fluids and decrease the fluid flow of seals, while increasing the sliding friction. We present results of interfacial fluid flow experiments on a hydrostatic column device which demonstrate how interfacial hydrophobicity can block fluid flow at interfaces and reduce the leak rate of seals. The presented results may help to understand the role of interfacial hydrophobicity in many practical applications, some of which we discuss briefly in this paper, e.g., rubber wiper blades on hydrophobic (usually wax-coated) glass, the locomotion of insects on surfaces in water, and syringes.

Nanodomain induced anomalous magnetic and electronic transport properties of LaBaCo2O5.5+δ highly epitaxial thin films

A giant magnetoresistance effect (∼46% at 20 K under 7 T) and anomalous magnetic properties were found in a highly epitaxial double perovskite LaBaCo₂O_5.5+δ (LBCO) thin film on (001) MgO. Aberration-corrected Electron Microscopy and related analytical techniques were employed to understand the nature of these unusual physical properties. The as-grown film is epitaxial with the c-axis of the LBCO structure lying in the film plane and with an interface relationship given by (100)_LBCO || (001)_MgO and [001]_LBCO || [100]_MgO or [010]_MgO. Orderly oxygen vacancies were observed by line profile electron energy loss spectroscopy and by atomic resolution imaging. Especially, oxygen vacancy and nanodomain structures were found to have a crucial effect on the electronic transport and magnetic properties.

[Specific gene therapy for hereditary retinal dystrophies - an update]

Treatment possibilities based on specific gene therapy strategies have become reality for a small number of patients with hereditary retinal dystrophies and are currently under investigation in several clinical trials worldwide. The most advanced studies are for patients suffering from mutations in the RPE65 gene. In addition, studies are ongoing for patients with disease causing mutations in the MERTK, REP1, ABCA4, or Myosin7A gene. Depending on the size of the gene copy to be transferred, two vectors are currently used in clinical trials: vectors based on adeno-associated virus (AAV) or on lentivirus (equine infectious anaemia virus, EIAV). An important aspect of current research includes the capacity to objectively measure the treatment effect in patients, since this is currently limited. This article gives an overview of the current state of specific gene therapy for hereditary retinal dystrophies.

Static or breakloose friction for lubricated contacts: the role of surface roughness and dewetting

We present experimental data for the static or breakloose friction for lubricated elastomer contacts, as a function of the time of stationary contact. Due to fluid squeeze-out from the asperity contact regions, the breakloose friction force increases continuously with the time of stationary contact. We consider three different cases: (a) PDMS rubber balls against flat smooth glass surfaces, (b) PDMS cylinder ribs against different substrates (glass, smooth and rough PMMA and an inert polymer) and (c) application to syringes. Due to differences in the surface roughness and contact pressures the three systems exhibit very different time dependences of the breakloose friction. In case (a) for rough surfaces the dry contact area A is a small fraction of the nominal contact area A0, and the fluid squeeze-out is fast. In case (b) the dry contact area is close to the nominal contact area, A/A0 ≈ 1, and fluid squeeze-out is very slow due to percolation of the contact area. In this case, remarkably, different fluids with very different viscosities, ranging from 0.005 Pa s (water–glycerol mixture) to 1.48 Pa s (glycerol), give very similar breakloose friction forces as a function of the time of stationary contact. In case (c) the contact pressure and the surface roughness are larger than in case (b), and the squeeze-out is very slow so that even after a very long time the area of real contact is below the percolation threshold. For all cases (a)–(c), the increase in the breakloose friction is mainly due to the increase in the area of real contact with increasing time, because of the fluid squeeze-out and dewetting.

Adhesion: role of bulk viscoelasticity and surface roughness

We study the adhesion between smooth polydimethylsiloxane (PDMS) rubber balls and smooth and rough poly(methyl methacrylate) (PMMA) surfaces, and between smooth silicon nitride balls and smooth PDMS surfaces. From the measured viscoelastic modulus of the PDMS rubber we calculate the viscoelastic contribution to the crack-opening propagation energy γeff(v,T) for a wide range of crack tip velocities v and for several temperatures T. The Johnson-Kendall-Roberts (JKR) contact mechanics theory is used to analyze the ball pull-off force data, and γeff(v,T) is obtained for smooth and rough surfaces. We conclude that γeff(v,T) has contributions of similar magnitude from both the bulk viscoelastic energy dissipation close to the crack tip, and from the bond-breaking process at the crack tip. The pull-off force on the rough surfaces is strongly reduced compared to that of the flat surface, which we attribute mainly to the decrease in the area of contact on the rough surfaces.

Rubber friction for tire tread compound on road surfaces

We have measured the surface topography and calculated the surface roughness power spectrum for an asphalt road surface. For the same surface we have measured the friction for a tire tread compound for velocities 10(-6) m s(-1) < v < 10(-3) m s(-1) at three different temperatures (at -8 °C, 20 °C and 48 °C). The friction data was shifted using the bulk viscoelasticity shift factor a(T) to form a master curve. We have measured the effective rubber viscoelastic modulus at large strain and calculated the rubber friction coefficient (and contact area) during stationary sliding and compared it to the measured friction coefficient. We find that for the low velocities and for the relatively smooth road surface we consider, the contribution to friction from the area of real contact is very important, and we interpret this contribution as being due to shearing of a very thin confined rubber smear film.

[Bilateral medial rectus recession with posterior fixation suture for large infantile esotropia]

BACKGROUND

Surgery for infantile large angle esotropia is not uniform. Bilateral medial rectus recession (BMR), combined recess-resect procedure, also combined with simultaneous contralateral medial rectus recession or secondary other procedures are common. Alternatively, bilateral medial rectus recession with posterior fixation suture (BMRF) has been used. We analysed the effect of BMRF for this specific indication.

PATIENTS AND METHODS

We undertook a retrospective evaluation of squint angles in simultaneous (S) and alternating (A) prism cover test before and 3 months after BMRF with and without additional oblique muscle surgery as primary surgery for esotropia ≥ 20° performed at our department between 1997 and 2009, as well as the rate of second procedures.

RESULTS

Sixty-one children (0.5 % of all patients who received eye muscle surgery during the same time interval) were included. Medians (10 % and 90 % quantiles) were: age at surgery 48.4 months (23.6; 76.0), refraction (spherical equivalent)2.25 dpt (0.25; 5.50), posterior fixation 5.5 mm + 13.0 mm (12.5; 13.0) from limbus, recession 5.0 mm (4.0; 5.0), inferior oblique recession in 29 children (27 bilateral), preoperative squint angles at 5 m S/A 29° (20; 40), at 0.3 m S/A 35° (24; 45), postoperative at 5 m S 0° (-6; 10), A 2° (-6; 11), at 0.3 m S 1° (-5; 12), A 3.5° (-5; 13), S ≤ 5° in 70.2 % at 5 m and 60.3 % at 0.3 m, consecutive exotropia 6-10° and > 10° in 7.0 and 3.5 % at 5 m and 8.6 and 1.7 % at 0.3 m, residual esotropia 6-10° and > 10° in 10.5 and 8.8 % at 5 m and 13.8 and 15.5 % at 0.3 m. Seven children (11.5 %) were re-operated for esotropia, four for exotropia (6.6 %).

CONCLUSION

Bilateral medial rectus recession with retroequatorial myopexy (Cüppers procedure) is an effective one-step procedure for large infantile esotropia. In roughly two-thirds of the cases, the squint angle was corrected within ± 5° with one surgery, which is similar to reported success rates of BMR.

[Autosomal recessive bestrophinopathy (ARB): a clinical and molecular description of two patients at childhood]

BACKGROUND

Autosomal recessive bestrophinopathy (ARB) is associated with mutations in BEST1. ARB is rarely diagnosed compared to BEST1-associated autosomal dominant (a. d.) juvenile vitelliform macular degeneration (Morbus Best, VMD). This is not only due to its low prevalence, but also to the phenotypic appearance. This paper describes typical features in two patients and discusses novel findings using improved ophthalmological diagnostic tools.

MATERIAL AND METHODS

Two unrelated boys with reduced visual acuity as well as five further relatives underwent a comprehensive ophthalmological examination including electroretinography (ERG) and electrooculography (EOG) according to ISCEV standard, fundus autofluorescence (FAF) and spectral-domain optic coherence tomography (SD‑OCT). BEST1 was screened for mutations based on the clinical diagnosis.

RESULTS

Visual acuity ranged between 0.2 and 0.5 in the patients. Multifocal yellowish paramacular and peripheral lesions were visible in the fundus correlating with spots of increased FAF. The lesions correlated with thickening of the RPE layer. Especially in the inner nuclear layer hyporeflective areas were visible, reminiscent of retinoschisis but without changes of FAF. In both patients the ganzfeld ERG was within the normal range and the mfERG presented obvious reductions of amplitudes in the central area. The EOG did not show a light peak. Goldmann perimetry was normal for isopters III/4e and I/4e. The fundus controlled perimetry revealed a central sensitivity loss. Molecular genetic analysis identified four (two novel) mutations in BEST1, in the compound heterozygous state in both patients. The screened relatives carried one of the mutations in the heterozygous state and were ophthalmologically unremarkable apart from age-related changes.

CONCLUSION

ARB is a rare disease, presenting with obvious differences to a.d. Mobus Best. The phenotype can easily be identified by the extramacular multifocal yellowish lesions with increased FAF and accompanied by early loss of visual acuity. Specific diagnostic tests like OCT, FAF recordings and electrophysiology support the diagnosis. Molecular genetic screening confirms the diagnosis and the autosomal recessive inheritance.

How to deal with diplopia

Diplopia is a frequent neuro-ophthalmologic symptom with diverse etiologies. This article describes elementary diagnostic tests and frequent causes of diplopia. Monocular diplopia persists when the other eye is closed and usually disappears when the patient looks through a pinhole. It is usually caused by errors in the optical media of the eye and has to be differentiated from spectacle-induced side effect and non-organic disorders. A sign of non-organic etiology is absence of change in image position when the head is tilted. Binocular diplopia disappears regardless of which eye is closed. Binocular diplopia occurs when the images of both eyes cannot be fused. The most frequent direct cause of diplopia is acquired strabismus. Knowledge of several specific types of strabismus enables efficient patient management. Congenital and decompensating strabismus like accommodative esotropia, pathophoria, strabismus surso- and deorsoadductorius, retraction syndrome, Brown's syndrome and esotropia in high myopia only need ophthalmologic treatment. Orbital injury, orbital tumor, ocular myositis, Graves orbitopathy and vascular disease usually require multidisciplinary management. Neurogenic paresis, superior oblique myokymia, ocular neuromyotonia, myasthenia, chronic progressive external ophthalmoplegia (CPEO), internuclear ophthalmoplegia (INO) and skew deviation require specific neurologic examination. Treatment of diplopia includes treatment of the fundamental disorder, monocular occlusion, prisms and strabismus surgery.

On the origin of why static or breakloose friction is larger than kinetic friction, and how to reduce it: the role of aging, elasticity and sequential interfacial slip

We discuss the origin of static friction and show how it can be reduced towards kinetic friction by the appropriate design of the sliding system. The basic idea is to use elastically soft solids and apply the external forces in such a way that different parts of the contacting interface start to slip at different times during the (tangential) loading process. In addition, the local slip must be large enough in order to result in a strong drop in the static friction force. We illustrate the theoretical predictions with the results of a simple model experiment.

[Blind spot enlargement syndrome in acute zonal occult outer retinopathy with detection of autoantibodies against the retinal antigens CRALBP and S-Ag]

Acute zonal occult outer retinopathy (AZOOR) is a rare disease and is part of the white dot syndrome occurring bilaterally and often asymmetrically in young healthy myopic women. Characteristic findings are distinct focal lesions of the outer segments (OS) of the photoreceptor (PR) layer and abnormalities in fundus autofluorescence (FAF) within the lesions. Currently there is a lack of defined disease criteria, such as specific laboratory findings. Also no effective therapy is known which makes it difficult to diagnose, differentiate and treat AZOOR. Supplementation of antioxidants may become part of therapeutic options in AZOOR. A 19-year-old myopic woman presented with unilaterally reduced visual acuity. Due to the clinical features and with the help of FAF, spectral domain optical coherence tomography (SD-OCT) and perimetry the diagnosis of blind spot enlargement syndrome in AZOOR was made. Identification of autoantibodies specific for two retinal antigens (CRALBP and S-Ag) supports the concept of an autoimmunological origin of the disease. Systemic steroids were given but stopped almost 6 weeks later as no improvement was seen. In follow-up controls over 12 months the clinical picture remained unchanged without any further therapy.

Field-induced continuous rotation of the polarization in multiferroic Mn0.95Co0.05WO4

We report the observation of a continuous rotation of the polarization in Mn0.95Co0.05WO4 under magnetic field. At zero field, this compound shows a transition into the spiral magnetic and ferroelectric phase at 12.2 K, which is the ground state, with the polarization oriented along the b-axis. Increasing b-axis magnetic fields rotate the ferroelectric polarization continuously toward the a-axis, indicating a rotation of the spin spiral plane. This rotation extends over a large field and temperature range. At a constant magnetic field of 3 T, the polarization also rotates from the a-axis at the ferroelectric transition toward the b-axis upon decreasing temperature.

Rubber friction: comparison of theory with experiment

We have measured the friction force acting on a rubber block slid on a concrete surface. We used both unfilled and filled (with carbon black) styrene butadiene (SB) rubber and have varied the temperature from -10 °C to 100 °C and the sliding velocity from 1 μm/s to 1000 μm/s. We find that the experimental data at different temperatures can be shifted into a smooth master-curve, using the temperature-frequency shifting factors obtained from measurements of the bulk viscoelastic modulus. The experimental data has been analyzed using a theory which takes into account the contributions to the friction from both the substrate asperity-induced viscoelastic deformations of the rubber, and from shearing the area of real contact. For filled SB rubber the frictional shear stress σ(f) in the area of real contact results mainly from the energy dissipation at the opening crack on the exit side of the rubber-asperity contact regions. For unfilled rubber we instead attribute σ(f) to shearing of a thin rubber smear film, which is deposited on the concrete surface during run in. We observe very different rubber wear processes for filled and unfilled SB rubber, which is consistent with the different frictional processes. Thus, the wear of filled SB rubber results in micrometer-sized rubber particles which accumulate as dry dust, which is easily removed by blowing air on the concrete surface. This wear process seams to occur at a steady rate. For unfilled rubber a smear film forms on the concrete surface, which cannot be removed even using a high-pressure air stream. In this case the wear rate appears to slow down after some run in time period.

[Surgery for strabismus sursoadductorius (congenital superior oblique palsy) in childhood]

PURPOSE

The aim of this study was to evaluate the effect of inferior oblique muscle recession (IOR) in children with pure unilateral strabismus sursoadductorius (so-called congenital superior oblique palsy, CSOP) operated before age 11 years.

PATIENTS AND METHODS

A retrospective study of IOR in children with unilateral CSOP and surgery before age 11 years was undertaken. In most cases, recession and anteroposition of the anterior part of the inferior oblique tendon next to the lateral edge of the inferior rectus muscle was performed without fixation of the posterior part of the tendon. Main outcome measures were change in abnormal head tilt, change in vertical deviation, both in straight and contralateral side gaze, and evaluation of squint angles.

RESULTS

Between 1997 and 2007, 36 consecutive children (aged 2 -10 years; 27 boys, 9 girls) received IOR for unilateral CSOP. The dose of IOR ranged between 6 and 12 mm. Vertical deviation in straight and contralateral gaze was reduced from median 5° (range 0 - 11°) and 12° (3 - 20°) to 0° (-2 - 8°) and 1° (-5 - 13°), respectively. Abnormal head tilt towards the contralateral shoulder was reduced from median 10° (0 - 20°) to 0° (-2,5 - 10°). Three children (8 %) received further extraocular muscle surgery within 2 years, one because of persistent hyperdeviation, and two because of consecutive hypodeviation of the operated eye.

CONCLUSIONS

The results indicate that IOR with fixation of only the anterior part of the inferior oblique to the sclera is an effective treatment for strabismus sursoadductorius/CSOP in children. Undercorrection into a residual, well compensated stage is a satisfying result. Both overcorrection and elevation deficiency were rare.

Fluid squeeze-out between rough surfaces: comparison of theory with experiment

We study the time dependence of the (average) interfacial separation between an elastic solid with a flat surface and a rigid solid with a randomly rough surface, squeezed together in a fluid. We use an analytical theory describing the fluid flow factors, based on the Persson contact mechanics theory and the Bruggeman effective medium theory, to calculate the removal of the fluid from the contacting interface of the two solids. In order to test this approach, we have performed simple squeeze-out experiments. The experimental results are compared to the theoretical predictions.

Autosomal recessive bestrophinopathy: new observations on the retinal phenotype - clinical and molecular report of an Italian family

PURPOSE

To describe the genotype and phenotype in a 9-year-old boy with bilateral retinopathy.

METHODS

The patient, his healthy (by history) nonconsanguineous parents and his sister were examined by best-corrected visual acuity, matrix frequency doubling technology, monocular static field analysis, fundus autofluorescence imaging, optical coherence tomography, Ganzfeld electroretinography (ERG), pattern ERG, multifocal ERG, electro-oculography and genotyping of the BEST1 gene.

RESULTS

The patient presented with an Arden ratio of 1.25, an unremarkable ERG and fluorescent yellow deposits distributed throughout the fundus suggestive of autosomal recessive bestrophinopathy (ARB). Genotyping revealed a homozygous nonsense mutation in BEST1 (p.R200X). The parents and the sister, who were heterozygous mutation carriers, presented with normal ophthalmological function.

CONCLUSIONS

ARB is a rare retinal disorder. We contribute a novel patient report indicative of ARB, assessed by clinical examination and confirmed by genotyping of BEST1, to the short list of ARB cases in the literature.