No abstract

Corticosteroids remain the mainstay of the treatment for various ocular conditions affecting the ocular surface, anterior and posterior segments of the eye due to their anti-inflammatory, anti-oedematous and anti-neovascularization properties. Prednisolone, prednisolone acetate, dexamethasone, triamcinolone acetonide, fluocinolone acetonide, and loteprednol etabonate are amongst the most widely used ophthalmic corticosteroids. Corticosteroids differ in their activity and potency in the eye due to their inherent pharmacological and pharmaceutical differences.Different routes and regimens are available for ocular administration of corticosteroids. Conventional topical application to the eye is the route of choice when targeting diseases affecting the ocular surface and anterior segment, while periocular, intravitreal, and suprachoroidal injections can 3 be potentially effective for posterior segment diseases. Corticosteroid-induced intraocular pressure elevation and cataract formation remain the most significant local risks following topical as well as systemic corticosteroid administration. Invasive drug administration via intracameral, subconjunctival and intravitreal injection can enhance ocular bioavailability and minimize dose and dosing frequency of administration, yet may exacerbate ocular side effects of corticosteroids. This review provides a critical appraisal of the ophthalmic uses of corticosteroid, routes of administration, drug delivery fundamentals and novel ocular implantable steroids delivery systems, factors influencing side effects and future perspectives for ocular corticosteroid therapy.

The lens, a major optical component of the eye, has a gradient refractive index, which is required to provide sufficient refractive power and image quality. The refractive index variations across the lens are dependent on the distributions and concentrations of the varying protein classes. In this study, we present the first measurements of the refractive index in the in situ eye lens from five species using a specially constructed X-ray Talbot grating interferometer. The measurements have been conducted in two planes: the one containing the optic axis (the sagittal plane) and the plane orthogonal to this (the equatorial plane). The results show previously undetected discontinuities and fluctuations in the refractive index profile that vary in different species. These may be linked to growth processes and may be the first optical evidence of discrete developmental stages.

BackgroundTo describe and compare visual function measures of two groups of school age children (6-14 years of age) attending a specialist eyecare practice in Austria; one group referred to the practice from educational assessment centres diagnosed with reading and writing difficulties and the other, a clinical age-matched control group.MethodsRetrospective clinical data from one group of subjects with reading difficulties (n = 825) and a clinical control group of subjects (n = 328) were examined.Statistical analysis was performed to determine whether any differences existed between visual function measures from each group (refractive error, visual acuity, binocular status, accommodative function and reading speed and accuracy).ResultsStatistical analysis using one way ANOVA demonstrated no differences between the two groups in terms of refractive error and the size or direction of heterophoria at distance (p > 0.05). Using predominately one way ANOVA and chi-square analyses, those subjects in the referred group were statistically more likely to have poorer distance visual acuity, an exophoric deviation at near, a lower amplitude of accommodation, reduced accommodative facility, reduced vergence facility, a reduced near point of convergence, a lower AC/A ratio and a slower reading speed than those in the clinical control group (p < 0.05).ConclusionsThis study highlights the high proportions of visual function anomalies in a group of children with reading difficulties in an Austrian population. It confirms the importance of a full assessment of binocular visual status in order to detect and remedy these deficits in order to prevent the visual problems continuing to impact upon educational development.

BackgroundThe enactment of the General Data Protection Regulation (GDPR) will impact on European data science. Particular concerns relating to consent requirements that would severely restrict medical data research have been raised.ObjectiveOur objective is to explain the changes in data protection laws that apply to medical research and to discuss their potential impact.MethodsAnalysis of ethicolegal requirements imposed by the GDPR.ResultsThe GDPR makes the classification of pseudonymised data as personal data clearer, although it has not been entirely resolved. Biomedical research on personal data where consent has not been obtained must be of substantial public interest.ConclusionsThe GDPR introduces protections for data subjects that aim for consistency across the EU. The proposed changes will make little impact on biomedical data research.

Aim: To measure corneal and scleral radii of curvature in response to intraocular pressure (IOP). Methods: Using digital photographic profile images of 16 fresh porcine eyes, the curvatures of the cornea and sclera were determined in response to five consecutive incremental 100 ml saline intravitreal injections. IOP was measured and ocular rigidity calculated. Elastic moduli of the cornea and sclera were estimated. Results: Intraocular pressure and the radius of curvature of the sclera increased linearly with increasing volume. There was no statistical change in corneal curvature. The elasticity of the cornea and sclera was constant during the 15-50 mm Hg increase in IOP. The estimated range of the elastic moduli of the cornea and sclera were, respectively 0.07-0.29 MPa and 0.2 MPa to 0.5 MPa. The scleral rigidity ranged from 0.0017 to 0.0022. Conclusions: The elastic moduli of the cornea and sclera are independent of IOP. The modulus of elasticity of the sclera is higher than that of the cornea. Elevation of IOP changes the curvature of the sclera but not that of the cornea. Porcine scleral rigidity is similar to human scleral rigidity. Scleral curvature could be a novel method for measuring IOP. F riedenwald 1 was the first to define scleral rigidity in terms of ocular volume and intraocular pressure (IOP). He realised that the sclera was important in understanding the effects of IOP on the optic nerve, and that the manifestations of glaucoma and the severity of its sequelae may be dependent on scleral rigidity. Recently, a non-linear finite element sensitivity study demonstrated that the stiffness of the sclera was the most important factor for determining the vulnerability of the optic nerve head to increasing IOP.2 This study demonstrated that even large strains of neural tissue had less effect on the optic nerve head than the indirect effects of IOP on the sclera. The effect of increasing IOP on scleral deformation has not been quantified. As the eyeball is a biological and a curved structure, a sensitive method is required to measure the small deformational changes induced by fluctuations in IOP. This study investigates the change in radii of curvatures of the fresh intact porcine cornea and sclera with IOP. Ocular rigidity is calculated and the ranges of elastic moduli of the cornea and sclera are estimated. METHODSSixteen porcine eyes were obtained from the local abattoir; eyes were collected was within 4 h of death and then transported on ice. All eyes were from animals aged 5.5 months. Experiments were completed between 3-6 h postmortem. During the preparation and experiment, samples were kept moist with saline solution. The extraocular muscles and extraneous fat were carefully removed from each eyeball and each specimen weighed on a digital balance before and after experimentation.At 20˚C, the eyeballs were placed, with their optic axes horizontal, on a specially designed base made of hollow, clear perspex tubing with gradation along the edge, to enable them to be maintained in a secure position duri...

The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height.

Lifelong eye lens function requires an appropriate gradient refractive index, biomechanical integrity and transparency. We conducted an extensive study of wild-type mouse lenses 1-30 months of age to define common age-related changes. Biomechanical testing and morphometrics revealed an increase in lens volume and stiffness with age. Lens capsule thickness and peripheral fiber cell widths increased between 2 to 4 months of age but not further, and thus, cannot account for significant age-dependent increases in lens stiffness after 4 months. In lenses from mice older than 12 months, we routinely observed cataracts due to changes in cell structure, with anterior cataracts due to incomplete suture closure and a cortical ring cataract corresponding to a zone of compaction in cortical lens fiber cells. Refractive index measurements showed a rapid growth in peak refractive index between 1 to 6 months of age, and the area of highest refractive index is correlated with increases in lens nucleus size with age. These data provide a comprehensive overview of age-related changes in murine lenses, including lens size, stiffness, nuclear fraction, refractive index, transparency, capsule thickness and cell structure. Our results suggest similarities between murine and primate lenses and provide a baseline for future lens aging studies.