A comparative multicentric long-term study of un-augmented modified Nishida procedure vs augmentation in unilateral sixth nerve palsy

PURPOSE

To compare the effectiveness of three procedures: modified Nishida procedure alone vs modified Nishida procedure combined with medial rectus recession (MRc) vs modified Nishida procedure combined with MRc and botulinum toxin (BT) for severe unilateral sixth nerve palsy.

DESIGN

Consecutive, interventional case series.

METHODS

The medical records of a consecutive series of patients with severe unilateral sixth nerve palsy who underwent modified Nishida procedure in multiple centres were reviewed. Surgical technique was decided preoperatively at the surgeon's discretion. The preoperative and postoperative findings were compared.

RESULTS

Of the 43 patients with abducens palsy that received the procedure, 32 were included (mean age 38.6 ± 19.8 years). Mean preoperative deviation was 63.0 ± 27.3 prism dioptres (PD) and mean limitation of abduction -4.5 ± 1.2. Five patients underwent a modified Nishida procedure alone, 24 patients had an additional MRc and 3 patients were also injected with BT. Overall, the average correction of modified Nishida technique by itself was 29.4 ± 6.6 PD (range 20-36) and adding a MRc corrected 62.6 ± 23.8 PD (range 24-120). Modified Nishida procedure, MRc and BT altogether corrected 95.0 ± 18.0 PD (range 75-110). No postoperative complications were observed in any of the patients.

CONCLUSIONS

Excellent outcomes with fewer complications are obtained with modified Nishida procedure alone. The need for additional procedures such as MRc and BT which increase the effect in primary position can be determined depending on passive duction and preoperative horizontal deviation.

Modified Nishida's procedure in a case of medial rectus hypoplasia

Introduction: We report a case of large angle exotropia in a child with limitation of adduction in the left eye with a radiological finding of hypoplastic medial rectus. Methods: A 3- year- old male child presented with left eye large angle exotropia, left face turn, -4 adduction limitation and severe amblyopia. Orbital imaging revealed hypoplasia of the medial rectus and intraoperatively a thin medial rectus was noted. The surgical procedure planned was lateral rectus recession combined with Modified Nishida's technique in the left eye. In this technique the superior and inferior recti were transposed medially by inserting non-absorbable sutures in the sclera posteriorly, closer to the upper and lower borders of the medial rectus muscle. Result: There was improvement in adduction of left eye and reduction of original deviation following maximal lateral rectus recession and a modified Nishida's approach. The early and optimal correction of exotropia also improved the compliance to patching with subsequent gain in visual acuity of the amblyopic eye. Conclusion: Modified Nishida's technique has the advantage of no muscle splitting and no tenotomy, remains a less invasive surgical procedure to correct large deviations. The modification of placing the bellies closer to medial rectus augments the effect and further improves adduction in cases with severe limitation of adduction. This technique can thus be considered as a possible surgical approach in young children with large angle exotropia due to hypoplastic medial rectus.

Latent Dirichlet allocation model for world trade analysis

International trade is one of the classic areas of study in economics. Its empirical analysis is a complex problem, given the amount of products, countries and years. Nowadays, given the availability of data, the tools used for the analysis can be complemented and enriched with new methodologies and techniques that go beyond the traditional approach. This new possibility opens a research gap, as new, data-driven, ways of understanding international trade, can help our understanding of the underlying phenomena. The present paper shows the application of the Latent Dirichlet allocation model, a well known technique in the area of Natural Language Processing, to search for latent dimensions in the product space of international trade, and their distribution across countries over time. We apply this technique to a dataset of countries’ exports of goods from 1962 to 2016. The results show that this technique can encode the main specialisation patterns of international trade. On the country-level analysis, the findings show the changes in the specialisation patterns of countries over time. As traditional international trade analysis demands expert knowledge on a multiplicity of indicators, the possibility of encoding multiple known phenomena under a unique indicator is a powerful complement for traditional tools, as it allows top-down data-driven studies.

Challenging Surgical Approach to a Lost Inferior Rectus Muscle Following Penetrating Orbital Trauma

A 37-year-old man suffered a penetrating left orbital injury with rupture of the inferior rectus muscle and avulsion of the optic nerve. The orbit was explored and the inferior rectus muscle stump was identified 25 mm from the limbus. Despite this, the muscle was successfully reattached and the patient achieved satisfactory postoperative alignment. [J Pediatr Ophthalmol Strabismus. 2019;56:e49-e52.].

Bilateral Symmetric and Asymmetric Superior Rectus Recession for Patients with Dissociated Vertical Deviation

PURPOSE

To evaluate the outcome of bilateral symmetric and asymmetric superior rectus (SR) recessions in patients with bilateral dissociated vertical deviation (DVD) without oblique dysfunction and determine factors that might influence the surgical outcome.

DESIGN

Retrospective study.

METHODS

All patients who underwent bilateral SR recession for bilateral DVD from January 2012 to December 2016 at an eye hospital in New Delhi, India were included. Indication for surgery was decompensated DVD in 1 or both eyes. Symmetric SR recession was performed for symmetric DVD and asymmetric SR recession was performed for asymmetric DVD of 10 prism diopters (PD) or more. Patients with a minimum follow-up of 6 months were included. Success was defined as absence of manifest DVD in both eyes at the final postoperative visit.

RESULTS

Medical records of 27 patients were analyzed. Their median age at surgery was 8 years [interquartile range (IQR), 6-10 years] and mean follow-up was 16.3 months (range, 6-48 months). Symmetric and asymmetric surgeries were performed in 19 and 8 patients, respectively. The amount of SR recession performed ranged from 5 to 10 mm. The median DVD reduced from 9 PD (IQR, 6-14 PD) to 5 PD (IQR, 3-8 PD) in the right eye (P = 0.015) and 9 PD (IQR, 7-12 PD) to 6 PD (IQR, 3-10 PD) in the left eye (P = 0.016) after surgery. Successful outcome was seen in 63% of patients. There was no difference in successful outcome with respect to age, sex, preoperative horizontal deviation, preoperative vertical deviation, postoperative residual horizontal deviation, surgical technique, asymmetry of SR recession, and magnitude of preoperative DVD. Patients with a preference for fixation were more likely to have a successful outcome.

CONCLUSIONS

Bilateral SR recession resulted in a success rate of 63% after single operation for bilateral DVD without oblique dysfunction. We found that the probability of a successful outcome did not depend on age at surgery, sex, preoperative horizontal or vertical deviation, magnitude of preoperative DVD, symmetry of SR recession, or surgical technique.

Geostatistical multimodel approach for the assessment of the spatial distribution of natural background concentrations in large-scale groundwater bodies

Quantification of the (spatially distributed) natural contributions to the chemical signature of groundwater resources is an emerging issue in the context of competitive groundwater uses as well as water regulation and management frameworks. Here, we illustrate a geostatistically-based approach for the characterization of spatially variable Natural Background Levels (NBLs) of target chemical species in large-scale groundwater bodies yielding evaluations of local probabilities of exceedance of a given threshold concentration. The approach is exemplified by considering three selected groundwater bodies and focusing on the evaluation of NBLs of ammonium and arsenic, as detected from extensive time series of concentrations collected at monitoring boreholes. Our study is motivated by the observation that reliance on a unique NBL value as representative of the natural geochemical signature of a reservoir can mask the occurrence of localized areas linked to diverse strengths of geogenic contributions to the groundwater status. We start from the application of the typical Pre-Selection (PS) methodology to the scale of each observation borehole to identify local estimates of NBL values. The latter are subsequently subject to geostatistical analysis to obtain estimates of their spatial distribution and the associated uncertainty. A multimodel framework is employed to interpret available data. The impact of alternative variogram models on the resulting spatial distributions of NBLs is assessed through probabilistic weights based on model identification criteria. Our findings highlight that assessing possible impacts of anthropogenic activities on groundwater environments with the aim of designing targeted solutions to restore a good groundwater quality status should consider a probabilistic description of the spatial distribution of NBLs. The latter is useful to provide enhanced information upon which one can then build decision-making protocols embedding the quantification of the associated uncertainty.

Pediatric Frontalis Suspension With Braided Polyester: A Comparison of Two Techniques

PURPOSE

To demonstrate the benefits of using braided polyester in the management of severe or recurrent ptosis in children and young adults and to compare the efficacy of two surgical techniques.

METHODS

Retrospective, non-randomized record review of 30 patients (43 eyelid procedures) affected by congenital or acquired severe ptosis who underwent frontalis suspension with braided polyester from 2008 to 2016. Two surgical techniques were compared: the base-down triangle and the Fox pentagon, both of which were performed using a closed technique. Functional success was defined as clearing of the visual axis. Complications and results were examined.

RESULTS

Functional success was obtained in 39 eyes of 43 procedures. Marginal reflex distance increased an average of 2.51 mm with the base-down triangle technique and 1.70 mm with the Fox pentagon technique (P = .05). The vertical palpebral fissure height increased an average of 4.60 mm with the base-down triangle technique and 2.45 mm with the Fox pentagon technique (P < .001). Mean follow-up duration was 38.6 months. Complications included untied suture (n = 2), suture dehiscence (n = 1), cellulitis (n = 2), and granuloma (n = 1).

CONCLUSIONS

Braided polyester was found to be a safe, effective, easy-to-handle, and low-cost sling material for frontalis suspension and should be considered for clinical use, especially in developing countries where the cost and availability of other materials represents a significant barrier to treatment. In the authors' experience, the base-down triangle technique appeared superior to the Fox pentagon technique. [J Pediatr Ophthalmol Strabismus. 2018;55(4):229-233.].

RESULTS OF RELID STUDY 2014-BUENOS AIRES, ARGENTINA RETROSPECTIVE EVALUATION OF LENS INJURIES AND DOSE

High levels of scatter radiation in catheterization laboratories may lead to posterior subcapsular opacities in the lens of the staff. The international Retrospective Evaluation of Lens Injuries and Dose (RELID) was performed in Argentina for the first time in 2010 in the context of the congress of the Latin American Society of Interventional Cardiology (SOLACI) and recently, in 2014, was carried out for the second time (SOLACI-CACI 2014). The 2014 study included 115 participants: interventional cardiologists, technicians and nurses. Posterior subcapsular lens changes typical of ionizing radiation exposure were found in 91.5% of interventional cardiologists, in 77% of technicians and in 100% of nurses, according to the Merriam-Focht scale. This RELID study (Argentina 2014) has particular importance since it allowed the follow-up of 10 professionals evaluated in 2010. The results obtained in the study population highlight the importance of the availability and proper use of the elements of radiation protection, as well as staff training.

Variants in SKP1, PROB1, and IL17B genes at keratoconus 5q31.1-q35.3 susceptibility locus identified by whole-exome sequencing

Keratoconus (KTCN) is a protrusion and thinning of the cornea, resulting in impairment of visual function. The extreme genetic heterogeneity makes it difficult to discover factors unambiguously influencing the KTCN phenotype. In this study, we used whole-exome sequencing (WES) and Sanger sequencing to reduce the number of candidate genes at the 5q31.1-q35.3 locus and to prioritize other potentially relevant variants in an Ecuadorian family with KTCN. We applied WES in two affected KTCN individuals from the Ecuadorian family that showed a suggestive linkage between the KTCN phenotype and the 5q31.1-q35.3 locus. Putative variants identified by WES were further evaluated in this family using Sanger sequencing. Exome capture discovered a total of 173 rare (minor allele frequency <0.001 in control population) nonsynonymous variants in both affected individuals. Among them, 16 SNVs were selected for further evaluation. Segregation analysis revealed that variants c.475T>G in SKP1, c.671G>A in PROB1, and c.527G>A in IL17B in the 5q31.1-q35.3 linkage region, and c.850G>A in HKDC1 in the 10q22 locus completely segregated with the phenotype in the studied KTCN family. We demonstrate that a combination of various techniques significantly narrowed the studied genomic region and reduced the list of the putative exonic variants. Moreover, since this locus overlapped two other chromosomal regions previously recognized in distinct KTCN studies, our findings suggest that this 5q31.1-q35.3 locus might be linked with KTCN.

Implications of the change in confinement status of a heterogeneous aquifer for scale-dependent dispersion and mass-transfer processes

A series of experimental tracer tests were performed to explore the implications of the change in the pressure status of a heterogeneous bimodal aquifer for scale-dependent dispersion and mass-transfer processes. The sandbox was filled with sands and gravel channels and patches to form an alluvial-like bimodal aquifer. We performed multiple injections of a conservative tracer from 26 different locations of the sandbox and interpreted the resulting depth-integrated breakthrough curves (BTCs) at the central pumping well to obtain a scale-dependent distribution of local and field-integrated apparent longitudinal dispersivity (respectively, α_L^loc and α_L^app). We repeated the experiments under confined (CS) and unconfined (UNS) pressure status, keeping the same heterogeneous configuration. Results showed that α_L^loc(associated with transport through gravel zones) was poorly influenced by the change in aquifer pressure and the presence of channels. Instead, α_L^app(i.e. macrodispersion) strongly increased when changing from CS to UNS. In specific, we found α_L^app≈0.03r for the CS and α_L^app≈0.15r for the UNS (being r the distance from the well). Second-to-fourth-order temporal moments showed strong spatial dependence in the UNS and no spatial dependence in the CS. These results seem consistent with a "vadose-zone-driven" kinetic mass-transfer process occurring in the UNS but not in the CS. The vadose zone enhances vertical flow due to the presence of free surface and large contrasts in hydraulic conductivity triggered by the desaturation of gravel channels nearby the pumping well. The vadose zone enhances vertical mixing between gravel and sands and generates BTC tailing. In the CS vertical mixing is negligible and anomalous transport is not observed.

Variant c.2262A>C in DOCK9 Leads to Exon Skipping in Keratoconus Family

PURPOSE

Keratoconus (KTCN) is a degenerative disorder of the eye that is characterized by a conical shape and thinning of the cornea, resulting in impaired visual function. Previously, we identified heterozygous single base-pair substitutions in DOCK9, IPO5, and STK24, showing concurrent 100% segregation with the affected phenotype in an Ecuadorian family. As the pathogenic consequences of these variants were not obvious, we performed in vitro splicing analyses to determine their functional significance.

METHODS

We generated expression constructs using patient DNA as a template corresponding to the wild-type and mutant alleles of DOCK9, IPO5, and STK24. After transfecting HeLa cells with each construct, total RNA samples were extracted, reverse transcribed, and amplified using specific primers.

RESULTS

In vitro splicing analysis revealed that only c.2262A>C in exon 20 of DOCK9 led to aberrant splicing, resulting in the changed ratio between two protein isoforms: a normal transcript and a transcript with exon skipping. The exon skipping causes a premature stop codon, disrupting the functional domains of DOCK9 protein, which may alter the biological role of DOCK9 as a Cdc42 activator.

CONCLUSIONS

Based on in vitro results, we demonstrated that c.2262A>C substitution in DOCK9, previously identified in KTCN-affected members of an Ecuadorian family, leads to a splicing aberration. However, because the mutation effect was observed in vitro, a definitive relationship between DOCK9 and KTCN phenotype could not be established. Our results indicate that further elucidation of the causes of KTCN is needed.

Assessment of natural background levels in potentially contaminated coastal aquifers

The estimation of natural background levels (NBLs) of dissolved concentrations of target chemical species in subsurface reservoirs relies on a proper assessment of the effects of forcing terms driving flow and transport processes taking place within the system and whose dynamics drive background concentration values. We propose coupling methodologies based on (a) global statistical analyses and (b) numerical modeling of system dynamics to distinguish between the impacts of different types of external forcing components influencing background concentration values. We focus on the joint application of a statistical methodology based on Component Separation and experimental/numerical modeling studies of groundwater flow and transport for the NBL estimation of selected chemical species in potentially contaminated coastal aquifers. We consider a site which is located in Calabria, Italy, and constitutes a typical example of a Mediterranean coastal aquifer which has been subject to intense industrial development. Our study is keyed to the characterization of NBLs of manganese and sulfate and is geared to the proper identification of the importance of a natural external forcing (i.e., seawater intrusion) on NBL assessment. Results from the Component Separation statistical approach are complemented by numerical simulations of the advective-dispersive processes that could influence the distribution of chemical species (i.e., sulfate) within the system. Estimated NBLs for manganese are consistent with the geochemical composition of soil samples. While Component Separation ascribes the largest detected sulfate concentrations to anthropogenic sources, our numerical modeling analysis suggests that they are mainly related to the natural process of seawater intrusion. Our results indicate that the use of statistical methodologies in complex groundwater systems should be assisted by a detailed characterization of the dynamics of natural (and/or induced) processes to distinguish effective anthropogenic contamination from natural conditions and to define realistic environmental clean-up goals.

Geochemical modeling of arsenic release from a deep natural solid matrix under alternated redox conditions

Dissolved arsenic (As) concentrations detected in groundwater bodies of the Emilia-Romagna Region (Italy) exhibit values which are above the regulation limit and could be related to the natural composition of the host porous matrix. To support this hypothesis, we present the results of a geochemical modeling study reproducing the main trends of the dynamics of As, Fe, and Mn concentrations as well as redox potential and pH observed during batch tests performed under alternating redox conditions. The tests were performed on a natural matrix extracted from a deep aquifer located in the Emilia-Romagna Region (Italy). The solid phases implemented in the model were selected from the results of selective sequential extractions performed on the tested matrix. The calibrated model showed that large As concentrations have to be expected in the solution for low crystallinity phases subject to dissolution. The role of Mn oxides on As concentration dynamics appears significant in strongly reducing environments, particularly for large water-solid matrix interaction times. Modeled data evidenced that As is released firstly from the outer surface of Fe oxihydroxides minerals exhibiting large concentrations in water when persistent reducing conditions trigger the dissolution of the crystalline structure of the binding minerals. The presence of organic matter was found to strongly affect pH and redox conditions, thus influencing As mobility.