Cornea and Sclera

Remington, Lee Ann

doi:10.1016/b978-1-4377-1926-0.10002-5

Cited by 8 publications

(4 citation statements)

References 125 publications

(139 reference statements)

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“…It is generally accepted that the width of the limbus is between 1 and 2 mm. 2 , 12 , 13 However, our study shows that the limbal width in the superior quadrant in Caucasian eyes is longer than 2 mm and that the limbal width in the nasal and temporal quadrants in Chinese Han eyes is shorter than 1 mm. Compared with the limbal widths in the Chinese group, the limbal widths in the US Caucasian population are 32.8% to 36.7% longer in all four limbal quadrants.…”

Section: Discussionmentioning

confidence: 52%

In Vivo Evaluation of the Limbus Using Anterior Segment Optical Coherence Tomography

Cordova

et al. 2018

Trans. Vis. Sci. Tech.

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PurposesTo investigate the limbal structure using anterior segment optical coherence tomography (AS-OCT) and compare the difference between a Chinese Han population and a Caucasian population.MethodsSixty healthy Chinese Han subjects (109 eyes, Chinese group) and 32 healthy Caucasian subjects (51 eyes, Caucasian group) were included in this comparative cross-sectional study. The central cornea and the superior, inferior, nasal, and temporal limbal regions of each subject underwent Fourier-domain AS-OCT. The following parameters were measured: corneal epithelial thickness (CET), maximum limbal epithelial thickness (LET), the mean LET, the width of limbus, distance between scleral spur and the location where limbal epithelium was the thickest (S-T), and limbal epithelial area between scleral spur and the end of Bowman's layer (LEA).ResultsCET was similar in both groups (P = 0.577). The width of limbus was more than 32.8% greater in all limbal quadrants in the Caucasian group (range, 1.25–2.20 mm) than in the Chinese group (range, 0.81–1.40 mm). S-T and LEA were also significantly higher in all limbal quadrants in the Caucasian group (all P < 0.001). The maximum LET and mean LET were 7.8% and 6.9% thicker at the nasal limbus and 8.1% and 8.7% thicker in the temporal limbus in Caucasian subjects than in Chinese subjects.ConclusionsThe limbal structures can be visualized using AS-OCT and differ significantly between the Caucasian and Chinese eyes.Translational RelevanceResearch of the limbus and surgeons performing procedures involving the limbal area should take into consideration of the anatomic differences especially when limbus is used as an anatomic reference.

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Section: Discussionmentioning

confidence: 52%

In Vivo Evaluation of the Limbus Using Anterior Segment Optical Coherence Tomography

Cordova

et al. 2018

Trans. Vis. Sci. Tech.

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“…Nonspecific absorption trough the conjunctiva, which covers the eye surface and the interior of the eyelids except the cornea (Figure 1), further reduces the remaining formulation available for transcorneal absorption [24]. The cornea, as detailed in Figure 1, is a highly differentiated tissue containing a lipophilic external epithelium and an internal endothelium separated by a thicker hydrophilic stroma [25,26]. This hydrophobicity gradient and an elevated presence of inter-cellular tight junctions within the epithelium hinder simple drug diffusion, which consequently relies on substance molecular weight and the hydrodynamic radius [2].…”

Section: Overcoming Ophthalmic Barriers With Lipid-based Nanocarriersmentioning

confidence: 99%

“…The cornea, as detailed in Figure 1 , is a highly differentiated tissue containing a lipophilic external epithelium and an internal endothelium separated by a thicker hydrophilic stroma [ 25 , 26 ]. This hydrophobicity gradient and an elevated presence of inter-cellular tight junctions within the epithelium hinder simple drug diffusion, which consequently relies on substance molecular weight and the hydrodynamic radius [ 2 ].…”

Section: Overcoming Ophthalmic Barriers With Lipid-based Nanocarriersmentioning

confidence: 99%

Lipid-Based Nanocarriers for Ophthalmic Administration: Towards Experimental Design Implementation

González-Fernández

Bianchera

Gasco³

et al. 2021

Pharmaceutics

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Nanotherapeutics based on biocompatible lipid matrices allow for enhanced solubility of poorly soluble compounds in the treatment of ophthalmic diseases, overcoming the anatomical and physiological barriers present in the eye, which, despite the ease of access, remains strongly protected. Micro-/nanoemulsions, solid lipid nanoparticles (SLN) or nanostructured lipid carriers (NLC) combine liquid and/or solid lipids with surfactants, improving drug stability and ocular bioavailability. Current research and development approaches based on try-and-error methodologies are unable to easily fine-tune nanoparticle populations in order to overcome the numerous constraints of ocular administration routes, which is believed to hamper easy approval from regulatory agencies for these systems. The predictable quality and specifications of the product can be achieved through quality-by-design (QbD) implementation in both research and industrial environments, in contrast to the current quality-by-testing (QbT) framework. Mathematical modelling of the expected final nanoparticle characteristics by variation of operator-controllable variables of the process can be achieved through adequate statistical design-of-experiments (DoE) application. This multivariate approach allows for optimisation of drug delivery platforms, reducing research costs and time, while maximising the understanding of the production process. This review aims to highlight the latest efforts in implementing the design of experiments to produce optimised lipid-based nanocarriers intended for ophthalmic administration. A useful background and an overview of the different possible approaches are presented, serving as a starting point to introduce the design of experiments in current nanoparticle research.

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“…Astigmatism is the condition of refraction in which the rays of light coming from a point source cannot produce a point on the retina [ 1 , 2 ]. Cornea is the major source of astigmatism in the optical system as it is responsible for about 74% of the total dioptric power of a normal eye [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Scheimpflug topographical changes after Femtosecond LASIK for mixed astigmatism – theoretical aspects and case study

Tăbăcaru¹,

Stanca²

2017

rjo

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Objective: To evaluate the corneal topographical changes after Femtosecond-LASIK surgery in eyes with mixed astigmatism. Methods:We present the analysis of the corneal Scheimpflug topographies of a patient treated with Femtosecond-LASIK technique for bilateral mixed astigmatism. Results: Three-dimensional reconstruction maps and differential anterior curvature maps were used to demonstrate the ablation profile and its stability in time. Conclusions: Visual and refractive results were very good after surgery, being topographically confirmed by the corneal reshaping which was performed as planned, the achieved ablation being stable during the one-year follow-up period.

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Cornea and Sclera

Cited by 8 publications

References 125 publications

In Vivo Evaluation of the Limbus Using Anterior Segment Optical Coherence Tomography

In Vivo Evaluation of the Limbus Using Anterior Segment Optical Coherence Tomography

Lipid-Based Nanocarriers for Ophthalmic Administration: Towards Experimental Design Implementation

Scheimpflug topographical changes after Femtosecond LASIK for mixed astigmatism – theoretical aspects and case study

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