Visual and physiological optics: introduction to the Journal of the Optical Society of America A feature issue

The 9th European Meeting on Visual Physiological Optics (VPO2018) was held August 29-31, 2018, in Athens, Greece. This issue of the Journal of the Optical Society of America A (JOSA A) is a dedicated feature, including numerous articles that span a large range of visual optics related topics, ranging from geometrical optics to visual psychophysics and from optical metrology to ophthalmic diagnostic technologies. The next VPO meeting will be held August 2020 in Cambridge, UK.

Cellular-scale evaluation of induced photoreceptor degeneration in the living primate eye

Progress is needed in developing animal models of photoreceptor degeneration and evaluating such models with longitudinal, noninvasive techniques. We employ confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT) and high-resolution retinal imaging to noninvasively observe the retina of non-human primates with induced photoreceptor degeneration. Photoreceptors were imaged at the single-cell scale in three modalities of adaptive optics scanning light ophthalmoscopy: traditional confocal reflectance, indicative of waveguiding; a non-confocal offset aperture technique visualizing scattered light; and two-photon excited fluorescence, the time-varying signal of which, at 730 nm excitation, is representative of visual cycle function. Assessment of photoreceptor structure and function using these imaging modalities revealed a reduction in retinoid production in cone photoreceptor outer segments while inner segments appeared to remain present. Histology of one retina confirmed loss of outer segments and the presence of intact inner segments. This unique combination of imaging modalities can provide essential, clinically-relevant information on both the structural integrity and function of photoreceptors to not only validate models of photoreceptor degeneration but potentially evaluate the efficacy of future cell and gene-based therapies for vision restoration.

Selective S Cone Damage and Retinal Remodeling Following Intense Ultrashort Pulse Laser Exposures in the Near-Infrared

Purpose

Infrared ultrashort pulse lasers are becoming increasingly popular for applications in the living eye. However, safety standards are not yet well established. Here we investigate retinal damage close to threshold for this pulse regime in the living macaque eye.

Methods

Retinal radiant exposures between 214 and 856 J/cm2 were delivered to the photoreceptor layer with an ultrashort pulse laser (730 nm, 55 fs, 80 MHz) through a two-photon adaptive optics scanning light ophthalmoscope. Retinal exposures were followed up immediately after and over several weeks with high-resolution reflectance and two-photon excited fluorescence ophthalmoscopy, providing structural and functional information.

Results

Retinal radiant exposures of 856 J/cm2 resulted in permanent S cone damage. Immediately after the exposure, the affected cones emitted about 2.6 times less two-photon excited fluorescence (TPEF) and showed an altered TPEF time course. Several weeks after the initial exposure, S cone outer and inner segments had disappeared. The space was filled by rods in the peripheral retina and cones near the fovea.

Conclusion

Interestingly, S cones are the receptor class with the lowest sensitivity in the near-infrared but are known to be particularly susceptible to ultraviolet and blue light. This effect of selective S cone damage after intense infrared ultrashort pulse laser exposure may be due to nonlinear absorption and distinct from pure thermal and mechanical mechanisms often associated with ultrashort pulse lasers.

[Cystic fibrosis : A new disease pattern in adult medicine]

Cystic fibrosis (CF) is an inherited incurable multi-organ disease. Improvement in treatment approaches over the last 20 years have led to an increased life expectancy where the number of adult patients has doubled and will continue to increase exponentially. Due to the use of new substances which modulate the basic defect, a substantial improvement in the prognosis can be assumed but the existing healthcare structures in Germany do not meet these rising needs. With more than 50% of patients being adults, there are only very few internal medicine centers available. Only approximately one third of the patients are treated in adult health centers. Adolescence in particular is a very vulnerable phase of the disease, the risk of comorbidities is increased and adherence to the very laborious treatment recommendations is as a rule low. While in many other countries transition programs have been evaluated and implemented for more than 20 years, in Germany there have only been rudimentary approaches to transition. Meanwhile investigations are available on the perceptions of adolescents with respect to coping with the disease and their treatment needs, including the perception of the time when the transition process should begin. Successful transition seems to be performed best in combined pediatric and adult centers, with the back-up of an experienced multidisciplinary team of healthcare providers.

Mesh-augmented versus direct abdominal closure in patients undergoing open abdomen treatment

Background

Open abdomen (OA) may be required in patients with abdominal trauma, sepsis or compartment syndrome. Vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM) is a widely used approach for temporary abdominal closure to close the abdominal wall. However, this method is associated with a high incidence of re-operations in short term and late sequelae such as incisional hernia. The current study aims to compare the results of surgical strategies of OA with versus without permanent mesh augmentation.

Methods

Patients with OA treatment undergoing vacuum-assisted wound closure and an intraperitoneal onlay mesh (VAC-IPOM) implantation were compared to VAWCM with direct fascial closure which represents the current standard of care. Outcomes of patients from two tertiary referral centers that performed the different strategies for abdominal closure after OA treatment were compared in univariate and multivariate regression analysis.

Results

A total of 139 patients were included in the study. Of these, 50 (36.0%) patients underwent VAC-IPOM and 89 (64.0%) patients VAWCM. VAC-IPOM was associated with reduced re-operations (adjusted incidence risk ratio 0.48 per 10-person days; CI 95% = 0.39–0.58, p < 0.001), reduced duration of stay on intensive care unit (ICU) [adjusted hazard ratio (aHR) 0.53; CI 95% = 0.36–0.79, p = 0.002] and reduced hospital stay (aHR 0.61; CI 95% = 0.040–0.94; p = 0.024). In-hospital mortality [22.5 vs 18.0%, risk difference − 4.5; confidence interval (CI) 95% = − 18.2 to 9.3; p = 0.665] and the incidence of intestinal fistula (18.0 vs 22.0%, risk difference 4.0; CI 95% = −10.0 to 18.0; p = 0.656) did not differ between the two groups. In Kaplan–Meier analysis, hernia-free survival was significantly increased after VAC-IPOM (p = 0.041).

Conclusions

In patients undergoing OA treatment, intraperitoneal mesh augmentation is associated with a significantly decreased number of re-operations, duration of hospital and ICU stay and incidence of incisional hernias when compared to VAWCM.

Electronic supplementary material

The online version of this article (10.1007/s10029-018-1798-9) contains supplementary material, which is available to authorized users.

[CF Lung Disease - a German S3 Guideline: Module 2: Diagnostics and Treatment in Chronic Infection with Pseudomonas aeruginosa]

Cystic Fibrosis (CF) is the most common autosomal-recessive genetic disease affecting approximately 8000 people in Germany. The disease is caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene leading to dysfunction of CFTR, a transmembrane chloride channel. This defect causes insufficient hydration of the epithelial lining fluid which leads to chronic inflammation of the airways. Recurrent infections of the airways as well as pulmonary exacerbations aggravate chronic inflammation, lead to pulmonary fibrosis and tissue destruction up to global respiratory insufficiency, which is responsible for the mortality in over 90 % of patients. The main aim of pulmonary treatment in CF is to reduce pulmonary inflammation and chronic infection. Pseudomonas aeruginosa (Pa) is the most relevant pathogen in the course of CF lung disease. Colonization and chronic infection are leading to additional loss of pulmonary function. There are many possibilities to treat Pa-infection. This is a S3-clinical guideline which implements a definition for chronic Pa-infection and demonstrates evidence-based diagnostic methods and medical treatment for Pa-infection in order to give guidance for individual treatment options.

Zuchtmanagement bei Spitzmaulnashörnern (Diceros bicornis michaeli) im Zoo Magdeburg

Gegenstand und Ziel: Das afrikanische Spitzmaulnashorn gehört zu den vom Aussterben bedrohten Tierarten. In Deutschland gibt es fünf Zoos, die diese Tierart halten, jedoch nicht in jedem Zoo wird erfolgreich gezüchtet. So fand im Magdeburger Zoo die letzte Geburt im Dezember 2005 statt. Seitdem konnten keine Deckakte mehr beobachtet werden. Während des Baus einer neuen Nashornanlage, die den Tieren durch die großzügigen Außenanlagen ein weitestgehend natürliches Paarungsverhalten ermöglicht, wurde der Reproduktionsstatus der Kühe untersucht und eine hormonelle Behandlung durchgeführt. Material und Methoden: Von zwei Spitzmaulnashornkühen (Diceros bicornis michaeli; „Mana“, 30 Jahre, und „Maleika“, 17 Jahre) wurden ab 2009 in regelmäßigen Abständen Kotproben gesammelt und die Konzentrationen von Pregnandiolglucuronid (PdG) mittels Enzym immunoassay und die von Östradiol mit Radioimmunoassay bestimmt. Nach der Auswertung der Hormonprofile wurden beide Tiere am Ende der PdG-dominierten Phase über 12 Tage mit Regumate® Equine, einem synthetischen Progesteron, behandelt. Ergebnisse: Die Nashornkuh „Mana“ ließ sich 11 Tage nach dem Absetzen des Medikaments decken und brachte im Dezember 2011 ein gesundes Kalb zur Welt. Bei „Maleika“ fand 13 Tage nach Behandlungsende ein Deckakt statt. Dem schlossen sich in der Folgezeit zwei weitere Kopulationen an. Ihr erstes Kalb wurde im Juli 2012 geboren. Schlussfolgerung und klinische Relevanz: Beide Kühe wurden gezielt mit dem synthetischen Progesteron Regumate Equine® behandelt und in der Folge vom Bullen gedeckt. Bei beiden Kühen kam es zeitnah zu einer Trächtigkeit und der Geburt eines Kalbes. Dieses handelsübliche Präparat eignet sich, um den ovariellen Zyklus bei weiblichen Spitzmaulnashörnern zu aktivieren, doch müssen Zeitpunkt der Medikation und Dosierung genau beachtet werden.

Regulatory T Cells Promote Natural Killer Cell Education in Mixed Chimeras

Therapeutic administration of regulatory T cells (Tregs) leads to engraftment of conventional doses of allogeneic bone marrow (BM) in nonirradiated recipient mice conditioned with costimulation blockade and mammalian target of rapamycin inhibition. The mode of action responsible for this Treg effect is poorly understood but may encompass the control of costimulation blockade-resistant natural killer (NK) cells. We show that transient NK cell depletion at the time of BM transplantation led to BM engraftment and persistent chimerism without Treg transfer but failed to induce skin graft tolerance. In contrast, the permanent absence of anti-donor NK reactivity in mice grafted with F1 BM was associated with both chimerism and tolerance comparable to Treg therapy, implying that NK cell tolerization is a critical mechanism of Treg therapy. Indeed, NK cells of Treg-treated BM recipients reshaped their receptor repertoire in the presence of donor MHC in a manner suggesting attenuated donor reactivity. These results indicate that adoptively transferred Tregs prevent BM rejection, at least in part, by suppressing NK cells and promote tolerance by regulating the appearance of NK cells expressing activating receptors to donor class I MHC.

Mechanical and biological effects of infiltration with biopolymers on 3D printed tricalciumphosphate scaffolds

The aim of this study was to evaluate the influence of infiltrating 3D printed (TCP) scaffolds with different biodegradable polymers on their mechanical and biological properties. 3D printed TCP scaffolds with interconnecting channels measuring 450±50 µm were infiltrated with four different biodegradable copolymers. To determine the average compressive strength, a uniaxial testing system was used. Additionally, scaffolds were seeded with MC3T3 cells and cell viability was assessed by live/dead-assay. Uninfiltrated TCP had an average compression strength of 1.92±0.38 MPa. Mechanical stability was considerably increased in all infiltrated scaffolds up to a maximum of 7.36±0.57 MPa. All scaffolds demonstrated high cell survival rates with a maximum of 94±10 % living cells. In conclusion, infiltration of 3D printed tricalcium phosphate scaffolds with biodegradable polymers significantly improved mechanical properties and biological properties were comparable to those of uninfiltrated TCP scaffolds.

Night myopia is reduced in binocular vision

Night myopia, which is a shift in refraction with light level, has been widely studied but still lacks a complete understanding. We used a new infrared open-view binocular Hartmann-Shack wave front sensor to quantify night myopia under monocular and natural binocular viewing conditions. Both eyes' accommodative response, aberrations, pupil diameter, and convergence were simultaneously measured at light levels ranging from photopic to scotopic conditions to total darkness. For monocular vision, reducing the stimulus luminance resulted in a progression of the accommodative state that tends toward the subject's dark focus or tonic accommodation and a change in convergence following the induced accommodative error. Most subjects presented a myopic shift of accommodation that was mitigated in binocular vision. The impact of spherical aberration on the focus shift was relatively small. Our results in monocular conditions support the hypothesis that night myopia has an accommodative origin as the eye progressively changes its accommodation state with decreasing luminance toward its resting state in total darkness. On the other hand, binocularity restrains night myopia, possibly by using fusional convergence as an additional accommodative cue, thus reducing the potential impact of night myopia on vision at low light levels.