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Orthokeratology (ortho-k) is the process of deliberately reshaping the anterior cornea by utilising specialty contact lenses to temporarily and reversibly reduce refractive error after lens removal. Modern ortho-k utilises reverse geometry lens designs, made with highly oxygen permeable rigid materials, worn overnight to reshape the anterior cornea and provide temporary correction of refractive error. More recently, ortho-k has been extensively used to slow the progression of myopia in children. This report reviews the practice of ortho-k, including its history, mechanisms of refractive and ocular changes, current use in the correction of myopia, astigmatism, hyperopia, and presbyopia, and standard of care. Suitable candidates for ortho-k are described, along with the fitting process, factors impacting success, and the potential options for using newer lens designs. Ocular changes associated with ortho-k, such as alterations in corneal thickness, development of microcysts, pigmented arcs, and fibrillary lines are reviewed. The safety of ortho-k is extensively reviewed, along with an overview of non-compliant behaviours and appropriate disinfection regimens. Finally, the role of ortho-k in myopia management for children is discussed in terms of efficacy, safety, and potential mechanisms of myopia control, including the impact of factors such as initial fitting age, baseline refractive error, the role of peripheral defocus, higher order aberrations, pupil size, and treatment zone size. [ABSTRACT FROM AUTHOR]

Purpose: To examine the variation in intraocular pressure (IOP) during the first six months of scleral lens wear.Methods: Thirty-two neophyte scleral lens wearers were recruited and IOP was measured using Goldman applanation tonometry before, and after 1 and 6 months of scleral lens wear (following lens removal). All scleral lenses were designed based on scleral topography or an impression of the ocular surface. Central corneal thickness and the central post-lens fluid reservoir thickness were quantified using optical coherence tomography.Results: Post-lens removal IOP displayed an increasing trend after 1 and 6 months of lens wear, but the magnitude of change was not clinically or statistically significant using several repeated measures analyses to account for sporadic missing longitudinal data (mean increase of 1 mmHg or less, p > 0.05). Central corneal thickness and the central post-lens fluid reservoir remained stable throughout the first six months of lens wear.Conclusion: IOP measured following lens removal did not vary significantly during the first 6 months of lens wear in scleral lens neophytes. Further research is required to determine if IOP varies during lens wear, following lens removal, or after longer-term lens wear due to suction forces or tissue compression beneath the landing zone. [ABSTRACT FROM AUTHOR]

Scleral contact lenses have a range of therapeutic and optical applications. In recent years, scleral lens prescribing has increased due to significant advances in ocular imaging technology, lens manufacturing processes, and the widespread availability of scleral lenses globally. While the optical principles of scleral lenses are identical to those of corneal rigid lenses (i.e. the post-lens tear layer neutralises the majority of anterior corneal astigmatism and higher order aberrations), the nature of scleral lenses and their typical fitting characteristics means that many of the assumptions of 'thin lens' paraxial optics traditionally used for corneal rigid lens calculations may be inappropriate in certain clinical scenarios. This review provides a comprehensive overview of a variety of lens and fitting characteristics that are unique to scleral lenses, or not typically encountered with corneal rigid lenses, and how these factors may potentially influence optical performance based on theoretical modelling, in particular; scleral lens parameters, the post-lens tear layer, and dynamic changes during lens wear. Current front and back surface lens designs and future scleral lens applications are also discussed, along with lens modifications to improve visual outcomes and transient changes in corneal optics induced by appropriately fitted modern scleral lenses. [ABSTRACT FROM AUTHOR]

Purpose: To describe a simple method to quantify scleral contact lens decentration using over-topography captured with a Placido ring videokeratoscope, and its repeatability.Methods: Scleral lens over-topography (E300 videokeratoscope, Medmont) was measured on 10 healthy participants following 15 min of lens settling (16.5 mm total diameter ICD miniscleral, Capricornia). Horizontal and vertical lens decentration was quantified from the translation of the front optic zone relative to the pupil centre derived from ellipses manually fitted to tangential power over-topography maps using both a standard and normalised dioptric scale. Intrasession (different maps captured within the same measurement session), intraobserver (identical maps analysed by the same observer), and intertechqniue (standard or normalised tangential power scales) repeatability were calculated.Results: The mean lens decentration was 0.62 ± 0.18 mm temporally and 0.91 ± 0.33 mm inferiorly. Lens decentration derived from tangential topography maps with a standard power scale were more repeatable (95% limits of agreement for intraobserver repeatability ± 0.07 mm and intrasession repeatability ± 0.15 mm) than measurements derived from normalised maps (95% limits of agreement for intraobserver repeatability ± 0.11 mm and intrasession repeatability ± 0.20 mm).Conclusions: Scleral lens decentration can be reliably quantified using tangential power maps with a standard (fixed) scale captured during over-topography without the need for customised instrumentation or image analysis software. This method has a range of potential applications in research and clinical practice. [ABSTRACT FROM AUTHOR]

Purpose: To develop a methodology to reliably determine the thickness profile of scleral contact lenses and examine the relationship between the centre and average lens thickness for a range of lens designs and back vertex powers.Methods: High-resolution images of 37 scleral trial lenses (Epicon LC, Rose K2 XL and ICD 16.5) were captured using an optical coherence tomographer, and their thickness profiles were generated after correcting for known measurement artefacts. Centre lens thickness values were compared with manual lens gauge measurements, and repeatability was assessed by comparing average thickness values derived from orthogonal meridians of each lens.Results: The imaging technique displayed a high level of agreement with a manual lens gauge for centre thickness measurements; mean difference 5 ± 9 μm (95% LoA -14 to +23 μm), and a very high level of repeatability; mean difference between orthogonal meridians 1 ± 3 μm (95% LoA -6 to +8 μm). Lens thickness profiles varied between lens designs, with distance from the lens centre, and with back vertex power. Increasing back vertex powers resulted in a significant over or underestimation (up to 33% for high minus powers) of the average lens thickness based on the centre lens thickness.Conclusions: The thickness of scleral contact lenses varies with distance from the lens centre and the back vertex power. The average lens thickness value derived from the entire lens provides a more appropriate representation of the true lens thickness and should be used in the calculation of scleral lens oxygen transmissibility. [ABSTRACT FROM AUTHOR]

Purpose: To examine the influence of centre thickness upon miniscleral lens flexure and the association between the magnitude of in-vivo lens flexure and scleral toricity.Methods: In-vivo lens flexure was measured using a videokeratoscope in 9 healthy young participants (25 ± 4 years) with normal corneae fitted with ICD 16.5 miniscleral lenses (hexafocon B material) with centre thicknesses of 150, 250, and 350 μm. Scleral toricity was determined from sagittal height data over a 15 mm chord obtained from a corneo-scleral topographer.Results: On average, lens flexure increased with decreasing centre thickness, but remained <0.50 D (mean increase <0.25 D, p = 0.63). Scleral toricity was positively correlated with in-vivo flexure for the 150 μm (r = 0.77, p = 0.02) and 250 μm (r = 0.72, p = 0.03) lenses. Using a group mean split, eyes with >200 μm scleral toricity exhibited greater in-vivo flexure than eyes with <200 μm (0.40 D more, averaged across all lenses, p = 0.02), and this effect was greatest for the 150 μm lens (0.61 D more, p = 0.04).Conclusions: Decreasing the centre thickness from 350 μm to 150 μm resulted in <0.25 D increase in lens flexure for a high Dk and low modulus material. Scleral toricity >200 μm was associated with more in-vivo lens flexure. When intentionally reducing scleral lens centre thickness to enhance oxygen transmissibility, customised back surface designs may be required to minimise in-vivo flexure in eyes with >200 μm scleral toricity at a 15 mm chord. [ABSTRACT FROM AUTHOR]

Purpose: To examine the magnitude and time course of central epithelial, stromal and total corneal thickness changes during sealed miniscleral contact lens wear and the influence of initial central corneal clearance upon these thickness changes.Methods: High-resolution OCT images were captured over an 8 h period of miniscleral contact lens wear (using a rotationally symmetric 16.5 mm diameter lens) in 15 young, healthy participants with normal corneae. Corneal thickness data were derived from OCT images using semi-automated image processing techniques over the central 4 mm.Results: Changes in stromal and total corneal thickness followed a similar pattern throughout lens wear with oedema first detected 15 min after lens insertion (0.47 ± 0.09% increase in stromal and total corneal thickness, both p < 0.01) which peaked after 90 min of lens wear (1.36 ± 0.24% increase in stromal and 1.18 ± 0.20% increase in total corneal thickness, both p < 0.01) and gradually decreased thereafter. Epithelial thickness increased slightly during the first 30 min of lens wear (0.56 ± 0.30% increase, p > 0.05), then rapidly decreased reaching a minimum thickness 480 min after lens insertion (2.38 ± 0.70% decrease, p < 0.05). The maximum total corneal oedema, maximum stromal oedema, and maximum epithelial thinning were not associated with the initial central corneal clearance or the extent of lens settling over the 8 h period (all p > 0.05). Greater initial central corneal clearance resulted in less oxygen concentration reaching the cornea (∼2% less) based on previously published data, which manifested as ∼0.5% more central corneal oedema.Conclusions: Scleral lens induced corneal oedema is stromal in nature. On average, central stromal and total corneal thickness increased rapidly following lens insertion and peaked after 90 min, while central epithelial thickness gradually decreased throughout lens wear consistent with natural diurnal variation. A greater initial central corneal clearance resulted in reduced oxygen delivery to the cornea, which had minimal short-term impact upon healthy eyes, however, minimising central corneal clearance may be important in eyes with reduced endothelial cell function to minimise hypoxic stress. [ABSTRACT FROM AUTHOR]

To report the characteristics (prevalence, severity, and location) of corneal epithelial microcysts and investigate associated risk factors in children wearing orthokeratology (ortho-k) lenses. Ninety-five myopic children wearing ortho-k lenses (examined by one of three independent investigators from March to September 2020) were included in this retrospective cross-sectional study. Pertinent data at baseline before ortho-k treatment and at the aftercare visits (the first visit when the microcysts were observed for children with microcysts, and the last visit before October 2020 for children without microcysts) were retrieved and analysed. A microcystic response was observed in 52.6% of children wearing ortho-k lenses. Children with high myopia (≥ 5.00 D) had a higher prevalence (100.0%, 23/23) and severity (69.5% (16/23) > grade 2 Efron scale) compared to children with low myopia (≤ 4.00 D) (prevalence of 37.5% (27/72) and 7.0% (5/72) > grade 2, p < 0.001). Microcysts were predominantly (86.0%) observed in the region of the inferior pigmented arc, typically originating in the inferior mid-peripheral cornea, and expanding over time into a semi- or whole annulus. Baseline myopia and topographical change at the treatment zone centre were significantly greater (p < 0.05) in low myopic children with microcysts (univariate analyses). During the COVID-19 pandemic, probably due to lifestyle changes, microcysts were frequently observed in children wearing ortho-k lenses and were associated with higher baseline myopia. Practitioners should examine ortho-k wearers with caution using a slit lamp with high magnification and illumination, especially the mid-peripheral cornea. The use of highly oxygen permeable lenses and frequent aftercare are necessary for ortho-k wearers, especially those with higher myopia. [ABSTRACT FROM AUTHOR]

Purpose: To examine the time course of the reduction in central corneal clearance and horizontal and vertical lens translation (decentration) during miniscleral contact lens wear and the theoretical influence upon the optics of the post-lens tear layer.Methods: Repeated high-resolution OCT images were captured over an 8h period of miniscleral contact lens wear (using a rotationally symmetric 16.5mm diameter lens) in 15 young, healthy participants with normal corneae. Central corneal clearance and lens decentration were derived from OCT images using semi-automated image processing techniques.Results: Central corneal clearance decreased exponentially over time, reducing by 76±8μm over 8h. Fifty percent of this reduction occurred within 45min of lens wear and seventy-five percent within 2h, with thinning of the post-lens tear layer plateauing 4h after lens insertion. Lens translation exhibited a similar pattern of change (0.18±0.04mm temporal and 0.20±0.09mm inferior decentration) stabilising 1.5-2h after insertion. The change in the lens fit over time resulted in a small reduction in the power of the post-lens tear layer (-0.12±0.01 D) and induced a prismatic effect of 0.01±0.16 Δ base out and 0.50±0.19 Δ base down relative to the pupil centre.Conclusions: For the miniscleral contact lens studied, horizontal and vertical lens decentration followed an exponential decay over 8h that plateaued approximately 2h after lens insertion, while central post-lens tear layer thinning plateaued after 4h of lens wear. [ABSTRACT FROM AUTHOR]

Upper Jurassic-lowermost Cretaceous carbonate build-ups are imaged on seismic data in the Black Sea. They form important, untested, hydrocarbon reservoirs that are the focus of active exploration. Outcrop analogues to these build-ups around the Black Sea contain a series of subaerial exposure surfaces. The hiatuses associated with a number of these subaerial exposure surfaces have been dated in a well exposed Callovian or Upper Oxfordian to Barremian shallow-water inner platform carbonate succession (the Berdiga Formation) in the Eastern Pontides using strontium isotope stratigraphy and foraminiferal biostratigraphy. They span the latest Kimmeridgian to Tithonian or Berriasian, and the Hauterivian to Barremian. Less well constrained, but broadly contemporaneous stratigraphic gaps in multiple successions around the Black Sea provide additional insights and point to a regional driving mechanism. The timing of hiatus formation does not correspond to periods of eustatic lowstand. It does coincide, however, with Late Tithonian to Berriasian and Hauterivian to Early Aptian episodes of rifting in the Greater Caucasus Basin, located farther to the north. Thus, it is possible that subaerial exposure was caused by rift flank uplift during periods of regional extension. Uplift due to slab break off is discounted as a control because it post-dates (rather than pre-dates) locally developed Kimmeridgian magmatism. Rift-flank uplift is likely to have also affected carbonate build-ups on the intervening rift shoulders of the eastern Black Sea, the Shatskiy Ridge and the Mid Black Sea High. At outcrop, subaerial exposure is often associated with karstification and secondary porosity development. Similar processes may have occurred in the offshore helping to enhance the reservoir quality of these exploration targets. [ABSTRACT FROM AUTHOR]

Refracting telescopes are afocal compound optical systems consisting of two lenses that produce an apparent magnification of the retinal image. They are routinely used in visual rehabilitation in the form of monocular or binocular hand held low vision aids, and head or spectacle-mounted devices to improve distance visual acuity, and with slight modifications, to enhance acuity for near and intermediate tasks. Since the advent of ground glass haptic lenses in the 1930's, contact lenses have been employed as a useful refracting element of telescopic systems; primarily as a mobile ocular lens (the eyepiece), that moves with the eye. Telescopes which incorporate a contact lens eyepiece significantly improve the weight, comesis, and field of view compared to traditional spectacle-mounted telescopes, in addition to potential related psycho-social benefits. This review summarises the underlying optics and use of contact lenses to provide telescopic magnification from the era of Descartes, to Dallos, and the present day. The limitations and clinical challenges associated with such devices are discussed, along with the potential future use of reflecting telescopes incorporated within scleral lenses and tactile contact lens systems in low vision rehabilitation. [ABSTRACT FROM AUTHOR]

Intraocular pressure (IOP) is maintained through complex and interrelated systems which control aqueous production and drainage, and it has been suggested that scleral lens (SL) wear may disrupt these vital homeostatic processes. This review provides an overview of anatomical and physiological processes that control IOP, identifies potential effects of SLs on these regulatory mechanisms, and examines studies that have attempted to quantify the effect of SLs on IOP. Lack of access to the cornea during SL wear makes accurate assessment of IOP challenging; therefore, a range of different assessment techniques and instruments have been employed to quantify IOP during and following SL wear. Some studies have evaluated IOP using standard techniques prior to lens application and following lens removal, or through a large central fenestration. Other studies have utilised instruments that facilitate assessment of IOP on the peripheral cornea or conjunctiva overlying the sclera (e.g. Schiotz, transpalpebral, and pneumatonometry). Two studies have recently evaluated changes in optic nerve structure during SL wear. Conflicting results have been reported on this topic, much of which examines changes in IOP in healthy subjects over limited periods of time. Currently, only a few studies have reported on long-term effects of SL wear on IOP in habitual SL wearers (after lens removal). Future research in this area must not only consider the fact that ocular conditions treated with SLs may potentially alter corneal biomechanical properties which can influence IOP, but also that these properties may be further altered by SL wear. Monitoring other risk factors for glaucoma (permanent alterations in optic nerve physiology, visual field defects) could provide a more comprehensive assessment of potentially increased risk of glaucomatous optic neuropathy due to SL wear. Ongoing clinical assessment of optic nerve structure and function is advisable in patients at risk for glaucoma who require SLs. [ABSTRACT FROM AUTHOR]

Purpose: To quantify the influence of short-term wear of miniscleral contact lenses on the morphology of the corneo-scleral limbus, the conjunctiva, episclera and sclera.Methods: OCT images of the anterior eye were captured before, immediately following 3h of wear and then 3h after removal of a miniscleral contact lens for 10 young (27 ± 5 years) healthy participants (neophyte rigid lens wearers). The region of analysis encompassed 1mm anterior, to 3.5mm posterior to the scleral spur. Natural diurnal variations in thickness were measured on a separate day and compensated for in subsequent analyses.Results: Following 3h of lens wear, statistically significant tissue thinning was observed across all quadrants, with a mean decrease in thickness of -24.1 ± 3.6 μm (p<0.001), which diminished, but did not return to baseline 3h after lens removal (-16.9 ± 1.9 μm, p<0.001). The largest tissue compression was observed in the superior quadrant (-49.9 ± 8.5 μm, p<0.01) and in the annular zone 1.5mm from the scleral spur (-48.2 ± 5.7 μm), corresponding to the approximate edge of the lens landing zone. Compression of the conjunctiva/episclera accounted for about 70% of the changes.Conclusions: Optimal fitting miniscleral contact lenses worn for three hours resulted in significant tissue compression in young healthy eyes, with the greatest thinning observed superiorly, potentially due to the additional force of the eyelid, with a partial recovery of compression 3h after lens removal. Most of the morphological changes occur in the conjunctiva/episclera layers. [ABSTRACT FROM AUTHOR]

Intracorneal haemorrhage is a rare complication of modern contact lens wear. While a limited number of reports have described intracorneal haemorrhages (typically stromal) associated with the extended wear of soft contact lenses with limited oxygen permeability for the correction of aphakia, this case report documents the management and resolution of a significant intraepithelial corneal haemorrhage associated with long-term rigid contact lens wear for keratoconus and high myopia. [ABSTRACT FROM AUTHOR]

Bullous keratopathy is a pathological corneal condition that arises due to irreversible oedema associated with endothelial cell loss or dysfunction. Symptoms may vary from mild (transient blurred vision and increased glare from epithelial oedema) to severe (an acute and significant loss of vision associated with frank endothelial decompensation, and pain due to ruptured epithelial bullae). Possible treatments to restore vision and minimise pain include topical hypertonic agents, bandage contact lenses, superficial anterior corneal surgical procedures or penetrating full thickness or endothelial keratoplasty. This case report describes a rare presentation of painless, bilateral, asymmetric bullous keratopathy with severe vision loss in an elderly male with non-insulin dependent diabetes mellitus. [ABSTRACT FROM AUTHOR]

Purpose To examine the influence of short-term miniscleral contact lens wear on corneal shape, thickness and anterior surface aberrations. Methods Scheimpflug imaging was captured before, immediately following and 3 h after a short period (3 h) of miniscleral contact lens wear for 10 young (mean 27 ± 5 years), healthy participants. Natural diurnal variations were considered by measuring baseline diurnal changes obtained on a separate control day without contact lens wear. Results Small but significant anterior corneal flattening was observed immediately following lens removal (overall mean 0.02 ± 0.03 mm, p < 0.001) which returned to baseline levels 3 h after lens removal. During the 3 h recovery period significant corneal thinning (−13.4 ± 10.5 μm) and posterior surface flattening (0.03 ± 0.02 mm) were also observed (both p < 0.01). The magnitude of posterior corneal flattening during recovery correlated with the amount of corneal thinning ( r = 0.69, p = 0.03). Central corneal clearance (maximum tear reservoir depth) was not associated with corneal swelling following lens removal ( r = −0.24, p > 0.05). An increase in lower-order corneal astigmatism Z (2,2) was also observed following lens wear (mean −0.144 ± 0.075 μm, p = 0.02). Conclusions Flattening of the anterior corneal surface was observed immediately following lens wear, while ‘rebound’ thinning and flattening of the posterior surface was evident following the recovery period. Modern miniscleral contact lenses that vault the cornea may slightly influence corneal shape and power but do not induce clinically significant corneal oedema during short-term wear. [ABSTRACT FROM AUTHOR]

Acquired limbal stem cell deficiency (LSCD) describes a condition in which the corneal limbal stem cells are altered or destroyed, typically due to ocular trauma, chronic allergy or inflammation. Idiopathic LSCD is a term used to describe limbal stem cell failure in the absence of any identifiable causative factor. While several cases of adult-onset LSCD have been identified previously, this case report describes a rare presentation of bilateral asymmetric idiopathic paediatric limbal stem cell deficiency in a sixteen-year-old male with an otherwise unremarkable ocular history. [ABSTRACT FROM AUTHOR]

In 2019, van der Worp et al. [[1]] encouraged the scleral lens community to elevate the evidence base for modern scleral lens practice by extending beyond retrospective chart audits and case series. The academics and clinicians who have contributed to this issue of Contact Lens and Anterior Eye have answered the call to help advance the science of sclerals. 43, 2020, 543-552 4 P. Kumar, P.K. Bandela, S.R. Bharadwaj, Do visual performance and optical quality vary across different contact lens correction modalities in keratoconus?. [Extracted from the article]

Abstract: The Eastern Black Sea is one of the few remaining underexplored hydrocarbon basins in Europe. Reservoir quality is a key risk factor in the basin. The analysis of up-dip portions of Oligocene to Pliocene depositional systems exposed around its northern and eastern margins enable the composition and provenance of sandstones within the basin to be predicted. Two major sources of quartz-rich sandstone are present: the Russian western Greater Caucasus, which became a subaerial sediment source in the Oligocene, and the East European Craton–Scythian Platform. These are predicted to form better quality reservoirs at shallow and moderate burial depths than their rock fragment-rich counterparts, due to lesser amounts of compactional porosity loss. Oligo-Miocene sandstones from the Russian western Greater Caucasus were deposited as turbidites in the Tuapse Trough. Sandstones from the East European Craton–Scythian Platform were largely trapped within the Indolo-Kuban Basin north of the Greater Caucasus. They only entered the Eastern Black Sea in large volumes from latest Miocene or Pliocene time in the region of the Kerch–Taman shelf at the western tip of the Greater Caucasus. However, it is possible that a precursor to this system supplied the Oligocene to Early Miocene reservoir sandstones within the Subbotina field. The Dziruli Massif, in western Georgia, also generated quartz-rich sandstones, but these are not thought to have entered the Black Sea. [Copyright &y& Elsevier]

Abstract: This study compared the corneal and total higher order aberrations between the fellow eyes in monocular amblyopia. Nineteen amblyopic subjects (8 refractive and 11 strabismic) (mean age 30±11years) were recruited. A range of biometric and optical measurements were collected from the amblyopic and non-amblyopic eye including; axial length, corneal topography and total higher order aberrations. For a sub-group of eleven non-presbyopic subjects (6 refractive and 5 strabismic amblyopes, mean age 29±10years) total higher order aberrations were also measured during accommodation (2.5D stimuli). Amblyopic eyes were significantly shorter and more hyperopic compared to non-amblyopic eyes and the interocular difference in axial length correlated with both the magnitude of anisometropia and amblyopia (both p <0.01). Significant differences in higher order aberrations were observed between fellow eyes, which varied with the type of amblyopia. Refractive amblyopes displayed higher levels of 4th order corneal aberrations C(4,0)(spherical aberration), C(4,2)(secondary astigmatism 90°) and C(4,−2)(secondary astigmatism along 45°) in the amblyopic eye compared to the non-amblyopic eye. Strabismic amblyopes exhibited significantly higher levels of C(3,3)(trefoil) in the amblyopic eye for both corneal and total higher order aberrations. During accommodation, the amblyopic eye displayed a significantly greater lag of accommodation compared to the non-amblyopic eye, while the changes in higher order aberrations were similar in magnitude between fellow eyes. Asymmetric visual experience during development appears to be associated with asymmetries in higher order aberrations, in some cases proportional to the magnitude of anisometropia and dependent upon the amblyogenic factor. [Copyright &y& Elsevier]

Abstract: The South Caspian Basin contains major hydrocarbon reservoirs within the largely Early Pliocene Productive Series. This paper describes and contrasts outcrops of the uppermost ∼500 m of the series (the Surakhany Suite) deposited by two of the main fluvial systems that supplied the Azeri margin of the basin. Sedimentary facies and, for the first time from the Productive Series, palynological analyses document fluvial channel belt complexes, sheetflood overbank and flood plain to flood plain lake environments. The Productive Series on the Apsheron Peninsula, Azerbaijan, was supplied predominantly from the north by the palaeo-Volga river system. It displays an overall fining-upward trend, such that the Surakhany Suite at Lokbatan is dominated by mudstone. Siltstone and coarser-grained sediments make up 28% of the section. Channel bodies are on average 1.5 m thick and form 13% of the succession. In the sub-surface of the Apsheron Peninsula, ratty wireline log responses also indicate that siltstone and sandstone bodies are predominantly thin bedded, with SP-derived net-to-gross sand ratios of ∼0.35–0.40. The succession in the Kura Basin was sourced predominantly from the west by the palaeo-Kura river system. It displays a coarsening-upward trend, such that in the middle and upper Surakhany Suite at Babazanan siltstone and coarser sediments make up 52% of the section. It is characterised by numerous stacked and laterally continuous channel sandstone bodies that are on average 5.8 m thick and comprise 42% of the outcrop. In the sub-surface of the Kura Basin, wireline log responses of the Surakhany Suite have a blocky character and indicate SP-derived net-to-gross sand ratios of 0.26–0.38. These values are similar to calculated sandstone volumes at outcrop (44%). The palynological data, including multivariate analyses, show that the main controls on palynomorph distribution are the degree of fluvial or lacustrine influence, subaerial exposure and salinity. Despite their more lithic nature, Surakhany Suite sandstones derived from the palaeo-Kura river system along the Kurovdag-Babazanan-Neftchala trend have similar or better petrophysical properties than those derived from the palaeo-Volga river on the Apsheron Peninsula and its offshore continuation. This is probably due to their coarser-grain size. This, combined with their greater sandstone body thickness, would suggest that the axis of the Kura Basin forms the most promising part of the Azeri sector of the South Caspian Basin for exploration within the uppermost part of the Productive Series. [Copyright &y& Elsevier]

Active deformation in the South Caspian region demonstrates the enormous variation in kinematics and structural style generated where a rigid basement block lies within a collision zone. Rigid basement to the South Caspian Basin moves with a westward component relative both to stable Eurasia and Iran, and is beginning to subduct at its northern and western margins. This motion is oblique to the approximately north–south Arabia–Eurasia convergence, and causes oblique shortening to the south and northeast of the South Caspian Basin: thrusting in the Alborz and Kopet Dagh is accompanied by range-parallel strike–slip faults, which are respectively left- and right-lateral. There are also arcuate fold and thrust belts in the region, for two principal reasons. Firstly, weaker regions deform and wrap around the rigid block. This occurs at the curved transition zone between the Alborz and Talysh ranges, where thrust traces are concave towards the foreland. Secondly, a curved fold and thrust belt can link a deformation zone created by movement of the basement block to one created by the regional convergence: west-to-east thrusts in the eastern Talysh represent underthrusting of the South Caspian basement, but pass via an arcuate fan of fold trains into SSW-directed thrusts in the eastern Greater Caucasus, which accommodates part of the Arabia–Eurasia convergence. Each part of the South Caspian region contains one or more detachment levels, which vary dependent on the pre-Pliocene geology. Buckle folds in the South Caspian Basin are detached from older rocks on thick mid-Tertiary mudrocks, whereas thrust sheets in the eastern Greater Caucasus detach on Mesozoic horizons. In the future, the South Caspian basement may be largely eliminated by subduction, leading to a situation similar to Archaean greenstone belts of interthrust mafic and sedimentary slices surrounded by the roots of mountain ranges constructed from continental crust. [Copyright &y& Elsevier]

Granier (2019) questioned the identification of a number of foraminifer species within the study of Vincent et al. (2018). We dispute his findings and provide supporting evidence for our original identifications. Our biostratigraphic work was carried out to support the strontium isotope stratigraphy study of an Upper Jurassic – Lower Cretaceous carbonate succession in the eastern Pontides, northeast Turkey. This was undertaken to constrain the age and duration of a number of hiatal surfaces within the succession that we proposed have geodynamic significance for the Black Sea region. Even if Granier's identifications are correct, they do not impact upon the conclusions of our study. Thus, rather than being a 'disappointing application of [a] geochemical tool', our study illustrates the utility of the powerful strontium isotope stratigraphy approach. • We dispute Granier's revision of our foraminifer identifications from NE Turkey. • We support our original interpretations with additional annotated illustrations. • The major stratigraphic gap in the section does not correspond to the Berriasian. • A Hauterivian age for the top of the section is compatible with our SIS data. • Granier's intervention does not affect the regional implications of our study. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the incidence and peak elevation of conjunctival prolapse during short-term open eye scleral lens wear and its association with lens fitting characteristics.Methods: Ten young, healthy adults (mean age ± SD, 30 ± 4 years) wore a high Dk sealed scleral lens for 90 min with an initial central post-lens fluid reservoir thickness defined as low (144 ± 23 μm), medium (487 ± 63 μm), and high (726 ± 55 μm). Optical coherence tomography was used to quantify limbal clearance, lens settling, and changes in conjunctival thickness.Results: The incidence of conjunctival prolapse was 37% across all fluid reservoir thickness conditions, with 80% of participants exhibiting conjunctival prolapse at least once. Prolapse was observed more frequently nasally (73%) than temporally (27%) (p < 0.01). The peak prolapse elevation did not vary with fluid reservoir thickness condition or anatomical location (both p > 0.05). For the low fluid reservoir thickness condition, eyes with conjunctival prolapse had greater initial limbal clearance (97 ± 38 μm compared to 43 ± 34 μm, p = 0.01) and more settling after 90 min of lens wear (-85 ± 30 μm compared to -34 ± 29 μm, p < 0.01). Greater limbal settling was associated with a higher peak elevation of the conjunctival prolapse (r = 0.48, p = 0.02), but not with landing zone tissue compression (r = 0.22, p = 0.33) or the initial or final limbal fluid reservoir thickness asymmetry (r ≤ 0.07, p > 0.05).Conclusion: Conjunctival prolapse was commonly observed during short-term sealed scleral lens wear in healthy eyes. The peak elevation of the conjunctival prolapse was associated with the extent of limbal settling, but not landing zone tissue compression or fluid reservoir thickness asymmetry. [ABSTRACT FROM AUTHOR]

Purpose: To examine the relationship between central post-lens fluid reservoir thickness and central corneal oedema during short-term closed eye scleral lens wear, and to compare these empirical oedema measurements with open eye lens wear data and current theoretical modelling for overnight scleral lens wear.Methods: Ten participants (mean ± standard error 30 ± 1 years) with normal corneas wore scleral lenses (Dk 141 × 10-11 cm3 O2(cm)/[(sec.)(cm2)(mmHg)) under closed eye conditions on separate days with an initial central post-lens fluid reservoir thickness considered to be low (160 ± 7 μm), medium (494 ± 17 μm), or high (716 ± 16 μm). Epithelial, stromal, and total corneal oedema were measured using high-resolution optical coherence tomography immediately after lens application and following 90 min of wear, prior to lens removal. Data were compared to open eye scleral lens induced corneal oedema and a theoretical model of overnight closed eye scleral lens wear (Kim et al., 2018).Results: Central corneal oedema was primarily stromal in nature and increased with increasing fluid reservoir thickness; the mean total corneal oedema was 3.86 ± 0.50%, 4.71 ± 0.28% and 5.04 ± 0.42% for the low, medium, and high thickness conditions, respectively. A significant difference in stromal and total corneal oedema was observed between the low and high fluid reservoir thickness conditions only (both p ≤ 0.01). Theoretical modelling overestimated the magnitude of central corneal oedema and the influence of fluid reservoir thickness upon corneal oedema during closed eye conditions.Conclusion: Scleral lens induced central corneal oedema during closed eye lens wear increases with increasing fluid reservoir thickness, but at a decreased rate compared to theoretical modelling. [ABSTRACT FROM AUTHOR]

While scleral lenses have been fitted using diagnostic lenses or impression moulding techniques for over a century, recent advances in anterior segment imaging such as optical coherence tomography and corneo-scleral profilometry have significantly improved the current understanding of the anatomy of the anterior eye including the morphometry of the conjunctiva, sclera, and corneo-scleral junction, as well as the ocular surface shape and elevation. These technological advances in ocular imaging along with continual improvements and innovations in scleral lens design and manufacturing have led to a global increase in scleral lens prescribing. This review provides a comprehensive overview of the conjunctiva and sclera in the context of modern scleral lens practice, including anatomical variations in healthy and diseased eyes, the physiological impact of scleral lens wear, potential fitting challenges, and current approaches to lens modifications in order to minimise lens-induced complications and adverse ocular effects. Specific topics requiring further research are also discussed. [ABSTRACT FROM AUTHOR]

Purpose: To examine the influence of short-term fenestrated scleral lens wear on intraocular pressure (IOP) in healthy eyes.Methods: IOP was measured before, during, and after a brief period (1-2 min) of fenestrated, scleral lens wear, using a rebound tonometer, in fifty, young healthy adults (mean age 23 ± 4 years) with normal corneas.Results: Immediately following lens insertion, 48 of the 50 (96 %) of participants displayed an increase in IOP (mean ± SD increase in these participants of 3.8 ± 2.0 mmHg). Immediately following lens removal, 50 % of participants displayed a reduction in IOP, equal to or lower than, the pre-insertion IOP (-1.0 ± 0.8 mmHg lower than baseline). The remaining 50 % of participants displayed an IOP slightly greater than the pre-insertion IOP (1.6 ± 1.0 mmHg greater) after lens removal.Conclusions: Short-term fenestrated scleral lens wear resulted in a small, but statistically significant, increase in IOP in 96 % of young healthy participants (< 4 mmHg on average), which decreased to a level similar to pre-lens insertion IOP levels immediately following lens removal. Further research is required to determine if this measured change in IOP during scleral lens wear is artefactual, or an elevation in the true IOP. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of lens centre thickness (and mass) upon short-term horizontal and vertical scleral lens decentration, and the association between both scleral topography and apical clearance, with lens decentration.Methods: Lens decentration was measured using over-topography data from 9 healthy young participants (25 ± 4 years) with normal corneae fitted with ICD 16.5 scleral lenses (hexafocon B material) with centre thicknesses of 150, 250, and 350 μm, while controlling for other lens parameters. Scleral toricity and elevation were determined from sagittal height data over a 15 mm chord obtained from a corneo-scleral topographer and central apical clearance was quantified using anterior segment optical coherence tomography.Results: The mean lens decentration was 0.55 ± 0.19 mm temporally and 0.84 ± 0.35 mm inferiorly, which did not vary significantly with centre thickness (p > 0.05). The mean nasal-temporal asymmetry in scleral elevation data was substantially greater (619 ± 67 μm) compared to the vertical meridian (369 ± 57 μm) (p < 0.01), and this variation in scleral topography along the horizontal meridian was associated with the magnitude of horizontal lens decentration (r = 0.68, p = 0.04). Greater initial central apical clearance was associated with more inferior lens decentration (r = -0.78, p = 0.01).Conclusion: Lens centre thickness and mass did not significantly influence centration. Horizontal lens decentration was associated with the nasal-temporal asymmetry in scleral elevation, while vertical lens decentration correlated with initial central apical clearance. Factors affecting scleral lens centration may vary between the horizontal and vertical meridians. [ABSTRACT FROM AUTHOR]

Purpose: To examine the influence of anterior segment optical coherence tomography imaging protocols on the intraobserver and intrasession repeatability of epithelial, stromal, and total corneal thickness measurements.Methods: Repeated anterior segment optical coherence tomography (AS-OCT) images (Spectralis, Heidelberg) were obtained from 15 adults using single 8.3 mm wide horizontal line scans with an average of 2, 10, 20, 30, 50 and 100 B-scans. Volumetric scans consisting of nine 8.3 mm horizontal line scans encompassing a 1.3 mm vertical region were also captured (with 20 B-scans per line scan). Single point thickness measures (at the normal to the tangent of the anterior corneal surface) were compared with thickness measures averaged over the central 6 mm. The impact of B-scan averaging and intraobserver variability were examined for single line scans. For volumetric scans, the impact of the number of line scans upon intraobserver and intrasession variability were calculated.Results: Intraobserver repeatability did not vary significantly as a function of the number of averaged B-scans per line scan, but was lowest for 20-30 averaged B scans. For volumetric scans, increasing the number of line scans did increase scan duration (p < 0.001), with minimal impact upon the average scan quality index (p = 0.06). Averaging more than 3 line scans did not significantly improve intraobserver or intrasession repeatability for either single point or average thickness measurements.Conclusion: AS-OCT volumetric scans with 3 lines each consisting of 20 B-scans with measurements averaged over a central 6 mm of the cornea provide highly repeatable measures of epithelial, stromal and total corneal thickness (95 % LoA ≤ ±3.2 μm for intraobserver repeatability and ≤ ±3.7 μm for intrasession repeatability). This scanning protocol can provide reliable information when monitoring subtle changes in corneal thickness. [ABSTRACT FROM AUTHOR]

Corneal techniques for enhancing near and intermediate vision to correct presbyopia include surgical and contact lens treatment modalities. Broad approaches used independently or in combination include correcting one eye for distant and the other for near or intermediate vision, (termed monovision or mini-monovision depending on the degree of anisometropia) and/or extending the eye's depth of focus [1]. This report reviews the evidence for the treatment profile, safety, and efficacy of the current range of corneal techniques for managing presbyopia. The visual needs and expectations of the patient, their ocular characteristics, and prior history of surgery are critical considerations for patient selection and preoperative evaluation. Contraindications to refractive surgery include unstable refraction, corneal abnormalities, inadequate corneal thickness for the proposed ablation depth, ocular and systemic co-morbidities, uncontrolled mental health issues and unrealistic patient expectations. Laser refractive options for monovision include surface/stromal ablation techniques and keratorefractive lenticule extraction. Alteration of spherical aberration and multifocal ablation profiles are the primary means for increasing ocular depth of focus, using surface and non-surface laser refractive techniques. Corneal inlays use either small aperture optics to increase depth of field or modify the anterior corneal curvature to induce corneal multifocality. In presbyopia correction by conductive keratoplasty, radiofrequency energy is applied to the mid-peripheral corneal stroma, leading to mid-peripheral corneal shrinkage and central corneal steepening. Hyperopic orthokeratology lens fitting can induce spherical aberration and correct some level of presbyopia. Postoperative management, and consideration of potential complications, varies according to technique applied and the time to restore corneal stability, but a minimum of 3 months of follow-up is recommended after corneal refractive procedures. Ongoing follow-up is important in orthokeratology and longer-term follow-up may be required in the event of late complications following corneal inlay surgery. [ABSTRACT FROM AUTHOR]

Changes in higher order aberrations (HOA's) and retinal image quality during accommodation have not previously been examined in children. This study measured ocular HOA's in ninety non-myopic, school-aged children during short-term accommodation tasks at 0, 3, 6, and 9 D demands presented via a Badal optometer mounted to a Hartmann-Shack wavefront aberrometer (COAS-HD, Wavefront Sciences). Eighty-four participants who exhibited active accommodation were included in the analyses. An eighth order Zernike polynomial was fit across a 2.3 mm, 4 mm, and natural pupil diameter to evaluate changes in refractive power vectors (M, J180, and J45), accommodation errors (lags and leads), HOA root mean square (RMS) variables, individual Zernike coefficients, and the visual Strehl ratio based on the optical transfer function (VSOTF). All HOA RMS variables changed significantly with accommodation, with the greatest change observed for the 9 D demand. Of the individual Zernike coefficients, primary (C40) and secondary spherical aberration (C60) exhibited the greatest magnitude of change, becoming negative and positive with increasing accommodation, respectively. The VSOTF changed significantly with greater accommodation for both the 4 mm and natural pupil size, becoming significantly worse for the 9 D demand. HOA's increase and retinal image quality decreases significantly during higher levels of accommodation in children, similar to adults. These findings provide a greater understanding of the optical properties of children's eyes and insights into possible mechanisms for the association between accommodation, near work, and refractive error development. [ABSTRACT FROM AUTHOR]

Scleral lenses can affect a range of anterior segment structures including the eyelids and the tears. The eyelids, consisting of the outer skin layer, the middle tarsal plate, and the posterior palpebral conjunctiva, provide physical protection and house the meibomian glands and cilia which have important and unique functions. Tears consist of a mix of aqueous, mucus, and lipidomic components that serve vital functions of lubricity, protection, and nourishment to the ocular surface. Both the eyelids and the tear film interact directly with scleral lenses on the eye and can affect but also be impacted by scleral lens wear. The purpose of this paper is to review the anatomy and physiology of the eyelids and tear film, discuss the effects and impacts of the scleral lenses on these structures, and identify areas that require further research. [ABSTRACT FROM AUTHOR]

Scleral lenses were the first type of contact lens, developed in the late nineteenth century to restore vision and protect the ocular surface. With the advent of rigid corneal lenses in the middle of the twentieth century and soft lenses in the 1970's, the use of scleral lenses diminished; in recent times there has been a resurgence in their use driven by advances in manufacturing and ocular imaging technology. Scleral lenses are often the only viable form of contact lens wear across a range of clinical indications and can potentially delay the need for corneal surgery. This report provides a brief historical review of scleral lenses and a detailed account of contemporary scleral lens practice including common indications and recommended terminology. Recent research on ocular surface shape is presented, in addition to a comprehensive account of modern scleral lens fitting and on-eye evaluation. A range of optical and physiological challenges associated with scleral lenses are presented, including options for the clinical management of a range of ocular conditions. Future applications which take advantage of the stability of scleral lenses are also discussed. In summary, this report presents evidence-based recommendations to optimise patient outcomes in modern scleral lens practice. [ABSTRACT FROM AUTHOR]

Contact lens evidence-based academic reports (CLEAR), Rigid corneal lens, Abbreviations, Overnight wear. [Extracted from the article]

Keratoconus is a bilateral and asymmetric disease which results in progressive thinning and steeping of the cornea leading to irregular astigmatism and decreased visual acuity. Traditionally, the condition has been described as a noninflammatory disease; however, more recently it has been associated with ocular inflammation. Keratoconus normally develops in the second and third decades of life and progresses until the fourth decade. The condition affects all ethnicities and both sexes. The prevalence and incidence rates of keratoconus have been estimated to be between 0.2 and 4,790 per 100,000 persons and 1.5 and 25 cases per 100,000 persons/year, respectively, with highest rates typically occurring in 20- to 30-year-olds and Middle Eastern and Asian ethnicities. Progressive stromal thinning, rupture of the anterior limiting membrane, and subsequent ectasia of the central/paracentral cornea are the most commonly observed histopathological findings. A family history of keratoconus, eye rubbing, eczema, asthma, and allergy are risk factors for developing keratoconus. Detecting keratoconus in its earliest stages remains a challenge. Corneal topography is the primary diagnostic tool for keratoconus detection. In incipient cases, however, the use of a single parameter to diagnose keratoconus is insufficient, and in addition to corneal topography, corneal pachymetry and higher order aberration data are now commonly used. Keratoconus severity and progression may be classified based on morphological features and disease evolution, ocular signs, and index-based systems. Keratoconus treatment varies depending on disease severity and progression. Mild cases are typically treated with spectacles, moderate cases with contact lenses, while severe cases that cannot be managed with scleral contact lenses may require corneal surgery. Mild to moderate cases of progressive keratoconus may also be treated surgically, most commonly with corneal cross-linking. This article provides an updated review on the definition, epidemiology, histopathology, aetiology and pathogenesis, clinical features, detection, classification, and management and treatment strategies for keratoconus. [ABSTRACT FROM AUTHOR]

Mineralogical, geochemical and the potentiality of source shale rocks in the Khabour Formation from the Akkas-1 well, western Iraq and the Chia Zinnar section exposed in extreme northern Iraq were studied. Whole rock minerals observed are quartz, feldspars (labradorite, albite and orthoclase), pyrite and rare calcite. The main clay minerals observed in the studied shales are illite, chlorite, kaolinite, and mixed layer illite. SEM analysis shows that kaolinite is typically present as hexagonal plates and booklets, some of which are degraded, illite is commonly present as fibers and fine white flakes. Mixed layer illite is commonly observed as framboidal shapes while chlorite is observed as disc-shaped chlorite. Two samples from the upper, Hirnantian, part of the Akkas-1 well exhibit great differences from post Archean Australian shale (PAAS) in both major and trace element geochemistry. This is in contrast to the 13 other samples from the Akkas-1 well which have a trace element composition very close to PAAS. These differences are hard to interpret but they may record the impact of the Hirnantian glaciation. Common redox indicators (Th/U, Cu/Zn, V/Rb, Mn) all suggest an oxic environmental conditions prevailed during deposition of the Khabour Formation in the Akkas-1 well; this is supported by low TOC values. Khabour shales from the Akkas-1 well are organically lean (TOC 0.04–0.84%) and are late to post mature for oil generation. They represent poor sedimentary organic matter (SOM) but the presence of bitumen in the samples suggest source rocks do exist in this part of the succession. The studied samples from the Chia Zinnar section (extreme northern Iraq) are organically lean (TOC <0.2%) and have no source potential. Acritarchs provide new age constraints for the Khabour Formation at outcrop in northern Iraq. Six samples from the Chia Zinnar section contain Tremadocian acritachs and are assigned to the PZ10 palynozone. The surface section is therefore a chronostratigraphical equivalent to the basal shale unit observed in the Akkas-1 well. • The paper deals with the older known rocks in Iraq. • Possible record the impact of the Hirnantian glaciation. • Source potential, paleoenvironmental (paleoredox) conditions. [ABSTRACT FROM AUTHOR]