Outcomes and surgical management of persistent fetal vasculature

ObjectiveTo analyse outcomes in different forms of persistent fetal vasculature (PFV).Methods and analysisRetrospective cohort study at a university-based practice of children presenting with PFV between 2011 and 2020. Exclusion criteria was surgical management outside of our institution and follow-up less than 1 month. Wilcoxon and Student’s t-tests were used for statistical analysis.ResultsForty-six eyes of 45 patients presented with PFV at 16.7±31.3 (median 2.8) months old with 32.6±29.8 (median 22.5) months of follow-up. Types of PFV included: mild combined anterior-posterior (23 eyes, 50%), severe combined anterior-posterior (18 eyes, 39%), severe anterior (3 eyes, 7%), mild anterior (1 eye, 2%) and posterior (1 eye, 2%). Thirty-two eyes (70%) underwent PFV surgical correction; lensectomy (13 mild combined), vitrectomy (3 mild combined), sequential lensectomy then vitrectomy (3 severe combined), combined lensectomy-vitrectomy (11 severe anterior or severe combined), laser retinopexy (1 mild combined). Five eyes required additional vitrectomy surgery for retinal detachment, fold or cyclitic membrane. Nine eyes developed glaucoma, six requiring Intraocular pressure (IOP)-lowering surgery. At final follow-up, 32 eyes had at least form vision and 6 eyes were aversive to light. Eight eyes, all which were severe combined, and four that did not undergo PFV surgery, were unable to detect light due to phthisis bulbi (7) and optic nerve hypoplasia (1).ConclusionsClassification of PFV is important in determining surgical approach with severe cases often requiring both lensectomy and vitrectomy for optimal anatomic and functional outcomes.

Spectacular crinkled crust—A detachment fold train in the Carmel Formation, western San Rafael Swell, Utah

Imagine slipping on a small rug overlying a hardwood floor. In the process of sliding along the floor the rug produces a series of small folds and the rug moves forward from its original position. The same could be said for the “crinkled crust,” or folded layers of rocks in a detachment fold train. A spectacular detachment fold train, consisting of over 100 small, regularly spaced convex-upward folds called anticlines in gypsum-rich rock layers of the Middle Jurassic (about 168 million years ago [Ma]) Carmel Formation, is exposed immediately north of Interstate 70 (I-70) in the San Rafael Swell of east-central Utah (figures 1 and 2). The SanRafael Swell, a large anticlinal uplift, is an icon for everything that makes the Colorado Plateau dramatically scenic and geologically classic. However, the fold train is located in drab-colored, relatively featureless rock layers of the Carmel Formation in an area called Reed Wash along the gently dipping west flank of the Swell. After passing magnificent canyons, buttes, and mesas both to the east and west along I-70, the fold train typically goes unnoticed by not only the average tourist but geologists as well. Once the fold train is pointed out, the geologic observer is immediately struck with awe at this large, well-exposed, complex structural feature. Literally hundreds of classic geologic sites are well displayed in the San Rafael Swell; many are easily accessed overlooks and viewpoints. The detachment fold train, by contrast, is chosen as a geosite for its geologic uniqueness, educational instruction, and research opportunities in structural geology.

Structural analysis of the Bogotá Anticline, Colombian Eastern Cordillera: Implications on deformational styles of the Llanos Foothills

In this study we describe and discuss a structural analysis of the Bogotá Anticline, based on the creation of a new geological map and structural cross sections, to propose a model of evolution for the folding. The Bogotá Anticline is a complex geological structure with important variations in vergence and geometry over very short distances. Because of that, its formation was previously associated with gravitational collapses. The Bogotá Anticline is located in the Bogotá Plateau, which is part of the axial zone of the Eastern Cordillera of Colombia. We propose that this fold displays a lateral variation that evidence different stages of deformation of a faulted detachment fold with a detachment horizon located in the Chipaque Formation. A proposed thrust fault located to the east of the structure could generate the necessary shortening for the formation of this fold. The proposed model may serve as an analogue in an earlier less deformed state for the folds observed in similar rocks of the Llanos foothills.

Stratigraphical and Structural Analyses of the Sagrma (Sagerma) Anticline, Sulaimani Area, Iraqi Kurdistan Region

The Sagrma anticline is a name for two parallel series of mountain peaks that are separated by a deep, wide and elongate valley which has width and length of 2 and 40 km respectively. The valley is called Qopy Qaradagh and it is beautiful picnic area for the people of the nearby Qaradagh town and surrounding villages. The anticline is located 40 kms to the south of Sulaimani city at the boundary between High and Low Folded Zones. Recently the anticline is subjected to intense geological and seismic survey for oil exploration and an oil well is drilled to depth of 3400 m without finding economic oil. The aim of the present study is updating the data about the stratigraphy and structure of the anticline with the critical review of the previous studies. It is also aimed to give the possible reasons for the absence of oil in the anticline. The Kolosh, Sinjar, Gercus (or Khurmala) and Pila Spi Formations are exposed in the core, lower limbs, middle limbs and upper limbs of the inner arc of anticline respectively. The Pila Spi, Oligocene rocks, and Lower Fars, and Upper Fars Formations are exposed along the upper, middle and lower part of the outer arc of the two limbs. The previously described Sagerma and Avanah Formations are not recorded in the present study and this is true for the previous growth strata (as a syn-sedimentary deformation) too. Structurally, the Sagrma anticline is a tight double plunging anticline and its northeastern limb steeper than southwestern one. The anticline is not formed by fault propagation fold as concluded previously but deformed by limb rotation by which a detachment fold is generated. The rotation has intensely deformed the core of the anticline and due to this deformation the possible existed oil is not preserved. The main detachment fold is further deformed into several smaller (parasitic) anticlines which they have either Z or S shape which can be called anticlinorium. The anticline is shorted, in some places, by a large lateral thrust.

Quality control and risk assessment of seismic profiles using area-depth-strain analysis

Area-depth-strain (ADS) analysis is a method for quantifying the structural style, balance, boundary displacement, detachment locations, and subseismic strain from a seismic profile, information that is particularly useful for quality control and risk analysis. The method is based on measurements of excess area, width, depth, and bed length of multiple horizons in a structure. A balanced structure is indicated by a well-defined line or lines on an area-depth graph. The structural uncertainty or risk of the interpretation is quantified using the fit of the data to the least-squares line(s), the match between the ADS detachment values and the interpreted geometry, and the magnitudes of the calculated strains. The method also clearly separates syntectonic (growth) units from nontectonic (pregrowth and no-growth) units. Different area-depth graph styles represent (1) classic detachment folds, fault-propagation folds, and ramp anticlines; (2) buckle-style detachment folds; and (3) fault-bend folds. The focus here is on the first two. Numerical models of the detachment fold styles show the similarities and differences between their geometries and ADS interpretations. Both styles are evaluated with seismic profiles across oilfield-scale structures. The Alpha/Bobo field, Nigeria, is a classic detachment fold, and an Angolan anticline is of the buckle style. Profiles across the Alpha/Bobo field before and after the first well was drilled demonstrate the improvement in the ADS interpretation of the lower detachment location and the reduction of layer-parallel strains in the revised profile. The Alpha/Bobo field and the Angola fold illustrate the distinction between growth and no-growth intervals and the interpretation of growth strata. Both fields show the use of predicted versus observed ADS results to suggest possible improvements to the interpretation.