Is the human sclera a tendon-like tissue? A structural and functional comparison

Atta, Ghada; Tempfer, Herbert; Kaser-Eichberger, Alexandra; Traweger, Andreas; Heindl, Ludwig M.; Schroedl, Falk

doi:10.1016/j.aanat.2021.151858

Cited by 6 publications

(2 citation statements)

References 135 publications

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“…However, sGAGs and collagen crimp have also been shown to be related in tendon, which is more comparable to the sclera in terms of sGAG content (approximately 10% in articular cartilage, approximately 2.5% in tendon, and approximately 1% in the sclera) and other anatomic features. 74 , 75 …”

Section: Discussionmentioning

confidence: 99%

Altered Structure and Function of Murine Sclera in Form-Deprivation Myopia

Brown

Kowalski

Paulus

et al. 2022

Invest. Ophthalmol. Vis. Sci.

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Purpose The sclera is believed to biomechanically influence eye size, facilitating the excessive axial elongation that occurs during myopigenesis. Here, we test the hypothesis that the sclera will be remodeled and exhibit altered biomechanics in the mouse model of form-deprivation (FD) myopia, accompanied by altered retinoid concentrations, a potential signaling molecule involved in the process. Methods Male C57 Bl/6J mice were subjected to unilateral FD ( n = 44 eyes), leaving the contralateral eye untreated (contra; n = 44). Refractive error and ocular biometry were measured in vivo prior to and after 1 or 3 weeks of FD. Ex vivo measurements were made of scleral biomechanical properties (unconfined compression: n = 24), scleral sulfated glycosaminoglycan (sGAG) content (dimethylmethylene blue: n = 18, and immunohistochemistry: n = 22), and ocular all-trans retinoic acid (atRA) concentrations (retina and RPE + choroid + sclera, n = 24). Age-matched naïve controls were included for some outcomes ( n = 32 eyes). Results Significant myopia developed after 1 (−2.4 ± 1.1 diopters [D], P < 0.001) and 3 weeks of FD (−4.1 ± 0.7 D, P = 0.025; mean ± standard deviation). Scleral tensile stiffness and permeability were significantly altered during myopigenesis (stiffness = −31.4 ± 12.7%, P < 0.001, and permeability = 224.4 ± 205.5%, P < 0.001). Total scleral sGAG content was not measurably altered; however, immunohistochemistry indicated a sustained decrease in chondroitin-4-sulfate and a slower decline in dermatan sulfate. The atRA increased in the retinas of eyes form-deprived for 1 week. Conclusions We report that biomechanics and GAG content of the mouse sclera are altered during myopigenesis. All scleral outcomes generally follow the trends found in other species and support a retina-to-sclera signaling cascade underlying mouse myopigenesis.

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Section: Discussionmentioning

confidence: 99%

Altered Structure and Function of Murine Sclera in Form-Deprivation Myopia

Brown

Kowalski

Paulus

et al. 2022

Invest. Ophthalmol. Vis. Sci.

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“…The sclera is anteriorly lined by the conjunctiva. Its function is to maintain the shape of the bulb and to provide attachment to the tendons of the striated muscles of the eye [ 40 ]. The cornea is a transparent lamina without vessels (necessary conditions for the passage of light).…”

Section: Introductionmentioning

confidence: 99%

Fluorescent Nanosystems for Drug Tracking and Theranostics: Recent Applications in the Ocular Field

et al. 2022

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The greatest challenge associated with topical drug delivery for the treatment of diseases affecting the posterior segment of the eye is to overcome the poor bioavailability of the carried molecules. Nanomedicine offers the possibility to overcome obstacles related to physiological mechanisms and ocular barriers by exploiting different ocular routes. Functionalization of nanosystems by fluorescent probes could be a useful strategy to understand the pathway taken by nanocarriers into the ocular globe and to improve the desired targeting accuracy. The application of fluorescence to decorate nanocarrier surfaces or the encapsulation of fluorophore molecules makes the nanosystems a light probe useful in the landscape of diagnostics and theranostics. In this review, a state of the art on ocular routes of administration is reported, with a focus on pathways undertaken after topical application. Numerous studies are reported in the first section, confirming that the use of fluorescent within nanoparticles is already spread for tracking and biodistribution studies. The first section presents fluorescent molecules used for tracking nanosystems’ cellular internalization and permeation of ocular tissues; discussions on the classification of nanosystems according to their nature (lipid-based, polymer-based, metallic-based and protein-based) follows. The following sections are dedicated to diagnostic and theranostic uses, respectively, which represent an innovation in the ocular field obtained by combining dual goals in a single administration system. For its great potential, this application of fluorescent nanoparticles would experience a great development in the near future. Finally, a brief overview is dedicated to the use of fluorescent markers in clinical trials and the market in the ocular field.

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