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Clinical relevance: An analysis of the professional perspective of vision therapy (VT) by eye care professionals allows understanding the current controversies about this therapeutic option of which aspects can be improved for its correct application in clinical practice. Background: The aim of the current study was to analyse the perception of VT and the clinical protocols in this context followed among optometrists and ophthalmologists in Spain. Methods: A cross-sectional survey among Spanish optometrists and ophthalmologists. Google Forms tool was used to collect data via an online questionnaire divided into 4 sections (40 questions): consent to participate, demographic characteristics, opinion of the professional perspective of VT, and protocols. Only one submission from each email address was permitted by the survey tool. Results: A total of 889 Spanish professionals answered (age, 25–62 years): 848 optometrists (95.4%) and 41 ophthalmologists (4.6%). VT was considered as a scientifically-based procedure by 95.1% of participants, but its recognition and prestige was considered as low. The main cause reported for this was bad reputation or perception of placebo therapy (27.3%). The main indication of VT according to the surveyed professionals was convergence and/or accommodation problems (72.4%). Significant differences were found in the perception of VT among optometrists and ophthalmologists (p ≤ 0.027). A total of 45.3% of professionals reported performing VT in their current clinical practice. A combination of training sessions in office and home was regularly prescribed by 94.5% of them, but with significant variability in the duration of such sessions. Conclusions: VT is perceived by Spanish optometrists and ophthalmologists as a therapeutic option with scientific basis, but with limited recognition and prestige, although with more negative perception among ophthalmologists. A great variability was found in the clinical protocols followed between specialis

La miopía es el defecto refractivo del ojo más frecuente. En los últimos años, ha crecido la preocupación por el incremento exponencial de la prevalencia de la miopía en la población juvenil, existiendo una gran presión para la investigación y desarrollo de nuevas técnicas para la predicción y el control de la elongación axial del ojo, que es la principal responsable del crecimiento de la miopía. El riesgo de padecer enfermedades como glaucoma o maculopatías se incrementa muy significativamente a medida que la miopía aumenta. De ahí, la importancia de conocer si existen factores geométricos a nivel de esclera que nos permitan predecir qué casos son más susceptibles de cambios en esclera que conduzcan al alargamiento del ojo y, por consiguiente, al crecimiento de la miopía. Según la literatura, las tecnologías que aparecen actualmente clínicamente aplicables para el análisis de las propiedades geométricas de la estructura esclero-conjuntival se basan en el uso de la tomografía de coherencia óptica de segmento anterior (AS-OCT), la perfilometría o la cámara Scheimpflug. Las tecnologías de ASOCT necesitan una serie de mejoras para alcanzar una caracterización clínica precisa y reproducible de esta estructura. De las técnicas de perfilometria, la perfilometría de dominio de Fourier con el sistema Eye Surface Profiler (ESP) es actualmente la tecnología más avanzada de uso clínico disponible en Europa que proporciona un análisis muy completo de las propiedades geométricas de la estructura escleral-conjuntival humana. Dentro de las tecnologías de cámara Scheimpflug, ha aparecido recientemente en el mercado el módulo de perfil corneo escleral (CSP) del sistema Pentacam que permite obtener datos clínicos de la morfología escleral-conjuntival, especialmente para la adaptación de lentes de contacto esclerales y blandas. La comparación de las mediciones corneo-esclerales obtenidas con estos dos últimos sistemas (ESP y módulo CSP del Pentacam) ha permitido concluir que las medid

Purpose: To compare the sagittal height (SH) measurements and best fit sphere (BFS) scleral curvature obtained with two different diagnostic technologies. Methods: Prospective, nonrandomized, and comparative study analyzing 23 healthy eyes of 23 patients (age, 14–52 years) was conducted. A complete eye examination was performed including a corneoscleral topographic analysis with the Scheimpflug camera–based system Pentacam (Oculus GmbH, Wetzlar, Germany) and afterward with the Fourier domain profilometer Eye Surface Profiler (ESP) (Eaglet-Eye, Houten, the Netherlands). Differences between devices in temporal SH (TSH), nasal SH (NSH), and mean SH (MSH) measurements at 13- and 15-mm chord length and in scleral BFS were analyzed. Results: Statistically significant differences were found in TSH, NSH, and MSH obtained with Pentacam and ESP (P≤0.017), with a range of agreement from 0.21 to 1.28 mm, and a clear trend of the Pentacam system to provide higher SH measurements. Significant differences were found between Pentacam scleral BFS and ESP outer BFS (P<0.001) (range agreement, 3.57 mm). Significant correlations were found between spherical equivalent and differences between devices in 15-mm TSH (r=0.485; P=0.048), as well as between the difference between devices for some SH measurements and the magnitude of such SH values (r≥0.504; P≤0.014). Conclusion: Sagittal height and scleral BFS measurements obtained with the two devices are not interchangeable, with an increased difference in SH measures between devices in eyes with less myopic refractive error and increased SH values.

The main objective of the current study was to investigate further the relationship of the overall length of the eye with a great variety of anterior segment parameters, including scleral geometry. A total of 64 eyes of 32 participants with ages from 12 to 52 years were included in this prospective non-randomized single-center study. All participants underwent a complete eye examination, including an analysis of corneo-scleral shape with a Fourier-domain profilometer. A strong negative correlation was found between axial length and temporal-nasal ocular sagittal height difference for different chord lengths. For the right eye, a consistent and stable linear model was obtained to predict the axial length from the spherical equivalent, the corneal diameter, the high-order aberrations root mean square, and the minimum sagittal height for 13- and 14-mm chord. For the left eye, a model was obtained to predict the axial length from the spherical equivalent and the mean corneal curvature, including other parameters such as corneal diameter or high-order aberrations, depending on the chord length, considered for estimating the sagittal height values. More studies with larger samples are needed to confirm these preliminary outcomes.

Purpose: To evaluate the intrasession repeatability of corneal, limbal and scleral measurements obtained by an experienced operator with a Fourier transform profilometer in healthy eyes. Methods: Prospective, single-center study including 35 eyes of 35 participants with ages ranging from 13 to 52 years. All patients underwent three consecutive corneoscleral topographic evaluations with the Eye Surface Profiler (ESP) system (Eaglet Eye b.v.). Intrasession repeatability was analyzed for different geometric and sagittal height variables using the following parameters: the within-subject standard deviation (Sw) of the three consecutive measurements, intrasubject precision (1.96 × Sw), coefficient of variation (CV) and the intraclass correlation coefficient (ICC). Results: Inner best fit sphere (BFS) showed good repeatability, with ICC of 0.844. Higher variability was observed for the repeated measurements of limbus and outer BFS, with ICCs of 0.636 and 0.739, respectively. For mean corneal and scleral radius, ICCs were 0.933 and 0.888, respectively. The repeatability of all sagittal height data was good for all chords evaluated (11–15 mm), with Sw values from 0.02 to 0.11 mm, and ICCs from 0.568 to 0.909. A significant positive correlation was found between the magnitude of temporal-nasal sagittal height difference for all measured chords and its Sw associated. Conclusion: The ESP system can provide consistent measurements of sagittal height data for different chord diameters as well as for mean corneal and scleral radius in healthy eyes. Best fit approaches for limbal and scleral areas were less repeatable, although within a clinically acceptable range.

To revise the peer-reviewed literature on geometric properties of the scleral-conjunctival structure in order to define their clinical relevance and the potential relationship between their changes and myopia development or progression. A bibliographic search focused on the study of the geometry of conjunctiva and/or sclera as well as those studies evaluating the relationship between geometric changes in the scleral-conjunctival structure and myopia was carried out. Several studies have been performed with different diagnostic technologies, including optical coherence tomography, profilometry and Scheimpflug imaging, to detect geometric changes of the scleral-conjunctival tissue in different physiological conditions of the eye, after use of contact lenses and in different ocular pathologies. Likewise, these technologies have been shown to be a valuable clinical tool to optimize scleral contact lens fitting. Future studies should investigate new potential clinical applications of such technologies, including the evaluation of anterior scleral changes related to myopia, as well as to define standardized clinical standard operating procedures for obtaining accurate and reproducible clinical measurement of the scleral-conjunctival morphology.

Background: In case of signifcant imperfections on the cornea, data acquisition is difcult and a signifcant level of missing data could require the interpolation of important areas of the cornea, resulting in a very ambiguous model. The development of methods to defne in vivo customised geometric properties of the cornea based only on real raw data is extremely useful to diagnose and assess the progression of diseases directly related to the corneal architecture. The present work tries to improve the prognostic of corneal ectasia creating a 3D customised model of the cornea and analysing diferent geometric variables from this model to determine which variables or combination of them could be defned as an indicator of susceptibility to develop keratoconus. Methods: A corneal geometric reconstruction was performed using zonal functions and retrospective Scheimpfug tomography data from 187 eyes of 187 patients. Mor‑ phology of healthy and keratoconic corneas was characterized by means of geometric variables. The performance of these variables as predictors of a new geometric marker was assessed and their correlations were analysed. Results: The more representative variable to classify the corneal anomalies related to keratoconus was posterior apex deviation (area under receiver operating characteris‑ tic curve>0.899; p<0.0001). However, the strongest correlations in both healthy and pathological corneas were provided by the metrics directly related to the thickness, as deviations of the anterior/posterior minimum thickness points. Conclusions: The presented morphogeometric approach based on the analysis and custom geometric modelling of the cornea demonstrates to be useful for the charac‑ terization and diagnosis of keratoconus disease, stating that geometrical deformation is an efective marker of the ectatic disease’s progression.

Purpose: To evaluate and characterize long-term clinical changes in keratoconus cases not requiring surgical treatment because of the absence of clinically significant visual degradation and to design a predictive model for the progression rate. Methods: This retrospective longitudinal study enrolled 68 nonsurgically treated keratoconic eyes of 46 patients (age range, 18–66 years), with a follow-up period of 6 years ± 12 months. Visual, refractive, topographic, and aberrometric changes were evaluated, detecting the abnormal levels of longitudinal changes in each clinical variable analyzed (percentiles 10% or 90%). Subsequently, the eyes were stratified into progression and no-progression groups based on the different variables evaluated, analyzing baseline differences between them. A progression index (PI%) was defined, and its relationship with baseline data was modeled using multiple linear regression analysis. Results: Significant differences were detected in more quantity of baseline parameters between progression and no-progression groups for changes in sphere, spherical-like and coma-like root mean square, central mean keratometry (KM3mm), corneal asphericity (Q80mm), and central astigmatism (Ast3mm). The progression index (PI%) was defined using these variables, obtaining a mean value of 24.39 ± 51.09% and a median of 1.85%. This parameter was significantly related to the baseline sphere, K23 mm (steepest central keratometry), and Q80 mm (P < 0.001, R2 = 0.429). Conclusions: More pronounced progression seems to be present in myopic eyes with central localized steepening but normal mid-periphery flattening. A new index has been defined to characterize and predict the level of progression in nonsurgically treated keratoconus in a medium–long term.

There are numerous tomographic indices for the detection of keratoconus risk. When the indexes based on corneal volume are analyzed, two problems are presented: on the one hand, they are not very sensitive to the detection of incipient cases of keratoconus because they are not locally defined in the primary developmental region of the structural abnormalities; and on the other hand, they do not register the geometric decompensation driven by the asymmetry present during the disease progression. This work performed a morphogeometric modeling of the cornea by the aid of CAD tools and using raw topographic data (Sirius system, CSO, Firenze). For this method, four singular points present on the corneal surfaces were located and the following parameters based on corneal volume were calculated: VOLmct, defined by the points of minimal thickness; VOLaap, defined by the anterior corneal apex, and VOLpap, defined by the posterior corneal apex. The results demonstrate that a further reduction of corneal volume in keratoconus happens and significantly progresses along the disease severity level. The combination of optical and volumetric data, that collect the sensitivity of the asymmetry generated by the disease, allows an accurate detection of incipient cases and follow up of the disease progression.

The aim of this study is to describe a new keratoconus detection method based on the analysis of certain parametric morphogeometric operators extracted from a custom patient-specific three-dimensional (3D) model of the human cornea. A corneal geometric reconstruction is firstly performed using zonal functions and retrospective Scheimpflug tomography data from 107 eyes of 107 patients. The posterior corneal surface is later analysed using an optimised computational geometry technique and the morphology of healthy and keratoconic corneas is characterized by means of geometric variables. The performance of these variables as predictors of a new geometric marker is assessed through a receiver operating characteristic (ROC) curve analysis and their correlations are analysed through Pearson or Spearman coefficients. The posterior apex deviation variable shows the best keratoconus diagnosis capability. However, the strongest correlations in both healthy and pathological corneas are provided by the metrics directly related to the thickness as the sagittal plane area at the apex and the sagittal plane area at the minimum thickness point. A comparison of the screening of keratoconus provided by the Sirius topographer and the detection of corneal ectasia using the posterior apex deviation parameter is also performed, demonstrating the accuracy of this characterization as an effective marker of the diagnosis and ectatic disease progression.

The aim of this study was to describe the application of a new bioengineering graphical technique based on geometric custom modelling capable to detect and to discriminate small variations in the morphology of the corneal surface. A virtual 3D solid custom model of the cornea was obtained employing Computer Aided Geometric Design tools, using raw data from a discrete and finite set of spatial points representative of both sides of the corneal surface provided by a corneal topographer. Geometric reconstruction was performed using B-Spline functions, defining and calculating the representative geometric variables of the corneal morphology of patients under clinical diagnosis of keratoconus.

To characterize corneal structural changes in keratoconus using a new morphogeometric approach and to evaluate its potential diagnostic ability.

Corneal ectatic disorders are characterized by a progressive weakening of the tissue due to biomechanical alterations of the corneal collagen fibers. Carbon nanostructures, mainly carbon nanotubes (CNTs) and graphene, are nanomaterials that offer extraordinary mechanical properties and are used to increase the rigidity of different materials and biomolecules such as collagen fibers. We conducted an experimental investigation where New Zealand rabbits were treated with a composition of CNTs suspended in balanced saline solution which was applied in the corneal tissue. Biocompatibility of the composition was assessed by means of histopathology analysis and mechanical properties by stress-strain measurements. Histopathology samples stained with blue Alcian showed that there were no fibrous scaring and no alterations in the mucopolysaccharides of the stroma. It also showed that there were no signs of active inflammation. These were confirmed when Masson trichrome staining was performed. Biomechanical evaluation assessed by means of tensile test showed that there is a trend to obtain higher levels of rigidity in those corneas implanted with CNTs, although these changes are not statistically significant (p > 0.05). Implanting CNTs is biocompatible and safe procedure for the corneal stroma which can lead to an increase in the rigidity of the collagen fibers.

Corneal ectatic disorders are characterized by a progressive weakening of the tissue due to biomechanical alterations of the corneal collagen fibers. Carbon nanostructures, mainly carbon nanotubes (CNTs) and graphene, are nanomaterials that offer extraordinary mechanical properties and are used to increase the rigidity of different materials and biomolecules such as collagen fibers. We conducted an experimental investigation where New Zealand rabbits were treated with a composition of CNTs suspended in balanced saline solution which was applied in the corneal tissue. Biocompatibility of the composition was assessed by means of histopathology analysis and mechanical properties by stress-strain measurements. Histopathology samples stained with blue Alcian showed that there were no fibrous scaring and no alterations in the mucopolysaccharides of the stroma. It also showed that there were no signs of active inflammation. These were confirmed when Masson trichrome staining was performed. Biomechanical evaluation assessed by means of tensile test showed that there is a trend to obtain higher levels of rigidity in those corneas implanted with CNTs, although these changes are not statistically significant (p>0.05). Implanting CNTs is biocompatible and safe procedure for the corneal stroma which can lead to an increase in the rigidity of the collagen fibers.

Currently available keratoprosthesis models (nonbiological corneal substitutes) have a less than 75% graft survival rate at 2 years. We aimed at developing a model for keratoprosthesis based on the use of poly(ethyl acrylate) (PEA)-based copolymers, extracellular matrix-protein coating and colonization with adipose-derived mesenchymal stem cells. Human adipose tissue derived mesenchymal stem cells (h-ADASC) colonization efficiency of seven PEA-based copolymers in combination with four extracellular matrix coatings were evaluated in vitro. Then, macroporous membranes composed of the optimal PEA subtypes and coating proteins were implanted inside rabbit cornea. After a 3-month follow-up, the animals were euthanized, and the clinical and histological biointegration of the implanted material were assessed. h-ADASC adhered and survived when cultured in all PEA-based macroporous membranes. The addition of high hydrophilicity to PEA membranes decreased h-ADASC colonization in vitro. PEA-based copolymer containing 10% hydroxyethyl acrylate (PEA-HEA10) or 10% acrylic acid (PEA-AAc10) monomeric units showed the best cellular colonization rates. Collagen plus keratan sulfate-coated polymers demonstrated enhanced cellular colonization respect to fibronectin, collagen, or uncoated PEAs. In vivo implantation of membranes resulted in an extrusion rate of 72% for PEA, 50% for PEA-AAc10, but remarkably of 0% for PEA-HEA10. h-ADASC survival was demonstrated in all the membranes after 3 months follow-up. A slight reduction in the extrusion rate of h-ADASC colonized materials was observed. No significant differences between the groups with and without h-ADASC were detected respect to transparency or neovascularization. We propose PEA with low hydroxylation as a scaffold for the anchoring ring of future keratoprosthesis.