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Investigative Ophthalmology & Visual... Nov 2023To evaluate whether pigmented guinea pigs with spontaneous myopia present characteristic changes of pathologic myopia.
PURPOSE
To evaluate whether pigmented guinea pigs with spontaneous myopia present characteristic changes of pathologic myopia.
METHODS
The fundus images of guinea pigs (3 weeks old) were graded according to fundus tessellation (FT) degree. Biometric parameters, including refraction, vitreous chamber depth (VCD), and axial length (AL), were measured at ages 21 and 43 days. Some of these animals were divided into three groups: hyperopic without FT (H w/o FT), myopic without FT (M w/o FT), and myopic with FT (M w/ FT). The horizontal and vertical radii of curvature of posterior sclera (RP-H and RP-V, respectively) and the radii of curvature and arc lengths of superior sclera (RS and LS, respectively), inferior sclera (RI and LI, respectively), nasal sclera (RN and LN, respectively), and temporal sclera (RT and LT) were evaluated by Fuji.
RESULTS
The fundi were graded as type A or type B (both without FT), type C (mild FT), or type D (severe FT). The prevalence of FT was correlated with myopic refraction, longer VCD, and longer AL. Eyes of M w/FT animals had shorter RP-H and RP-V, longer RS and RT, and longer LS and LT than eyes of H w/o FT or M w/o FT animals. Refractions shifted toward hyperopia in eyes lacking FT, but not in eyes having FT. The changes in VCD were consistent with the changes in refraction. This relatively myopic shift in refraction and shortening of VCD were found only in myopic eyes with FT, but not in myopic eyes without FT.
CONCLUSIONS
Spontaneously myopic guinea pig eyes have a high prevalence of FT. Myopic eyes with FT presented characteristic signs of pathologic myopia.
Topics: Guinea Pigs; Animals; Myopia; Anterior Eye Segment; Posterior Eye Segment; Refraction, Ocular; Sclera; Hyperopia
PubMed: 37962527
DOI: 10.1167/iovs.64.14.19 -
Clinical Ophthalmology (Auckland, N.Z.) 2023Lattice degeneration (LD), routinely diagnosed with indirect ophthalmoscopy, is one of the most common and clinically significant peripheral retinal findings. In this... (Review)
Review
Lattice degeneration (LD), routinely diagnosed with indirect ophthalmoscopy, is one of the most common and clinically significant peripheral retinal findings. In this review, we have summarized the data on currently available imaging techniques which help to improve diagnosis and our understanding of LD pathogenesis. Ultra-wide field imaging provides reliable color fundus capturing for the primary diagnosis of LD and may also be used as a screening tool. Wide-field imaging can be used for targeted documentation of LD lesions using true colors and with minimal optical distortions. Information on the status of the vitreoretinal interface, including detection of retinal holes, detachments, and vitreous tractions, can be obtained with peripheral structural optical coherence tomography (OCT) or scanning laser ophthalmoscopy in retro-mode. These techniques clarify the associated risks of rhegmatogenous retinal detachment. Fundus autofluorescence can provide details on atrophic changes. However, the risk of retinal detachment by means of this technique requires further investigation. OCT angiography may be successfully performed for some lesions. Taken together, OCT and OCT angiography demonstrate thinning of the choroid, alteration of local choroidal microcirculation, and, in severe lesions, involvement of the sclera. OCT angiography confirms loss of retinal microcirculation within LD lesion, which was previously shown with fluorescein angiography. In conclusion, despite relatively simple primary diagnosis, imaging of LD lesions remains challenging due to their peripheral localization. However, several new strategies, including ultra-wide field imaging, peripheral OCT, and scanning laser ophthalmoscopy, make LD imaging possible on a routine basis, improving diagnosis and understanding of LD pathogenesis.
PubMed: 37605766
DOI: 10.2147/OPTH.S405200 -
Progress in Retinal and Eye Research Sep 2023The limbus is a transition from the cornea to conjunctiva and sclera. In human eyes, this thin strip has a rich variation of tissue structures and composition, typifying... (Review)
Review
The limbus is a transition from the cornea to conjunctiva and sclera. In human eyes, this thin strip has a rich variation of tissue structures and composition, typifying a change from scleral irregularity and opacity to corneal regularity and transparency; a variation from richly vascularized conjunctiva and sclera to avascular cornea; the neural passage and drainage of aqueous humor. The limbal stroma is enriched with circular fibres running parallel to the corneal circumference, giving its unique role in absorbing small pressure changes to maintain corneal curvature and refractivity. It contains specific niches housing different types of stem cells for the corneal epithelium, stromal keratocytes, corneal endothelium, and trabecular meshwork. This truly reflects the important roles of the limbus in ocular physiology, and the limbal functionality is crucial for corneal health and the entire visual system. Since the anterior limbus containing epithelial structures and limbal epithelial stem cells has been extensively reviewed, this article is focused on the posterior limbus. We have discussed the structural organization and cellular components of the region beneath the limbal epithelium, the characteristics of stem cell types: namely corneal stromal stem cells, endothelial progenitors and trabecular meshwork stem cells, and recent advances leading to the emergence of potential cell therapy options to replenish their respective mature cell types and to correct defects causing corneal abnormalities. We have reviewed different clinical disorders associated with defects of the posterior limbus and summarized the available preclinical and clinical evidence about the developing topic of cell-based therapy for corneal disorders.
Topics: Humans; Limbus Corneae; Cornea; Epithelium, Corneal; Corneal Diseases; Stem Cells
PubMed: 37392960
DOI: 10.1016/j.preteyeres.2023.101192 -
Journal of Controlled Release :... Jul 2024Microneedles (MNs) are micron-sized needles, typically <2 mm in length, arranged either as an array or as single needle. These MNs offer a minimally invasive approach... (Review)
Review
Microneedles (MNs) are micron-sized needles, typically <2 mm in length, arranged either as an array or as single needle. These MNs offer a minimally invasive approach to ocular drug delivery due to their micron size (reducing tissue damage compared to that of hypodermic needles) and overcoming significant barriers in drug administration. While various types of MNs have been extensively researched, significant progress has been made in the use of hollow MNs (HMNs) for ocular drug delivery, specifically through suprachoroidal injections. The suprachoroidal space, situated between the sclera and choroid, has been targeted using optical coherence tomography-guided injections of HMNs for the treatment of uveitis. Unlike other MNs, HMNs can deliver larger volumes of formulations to the eye. This review primarily focuses on the use of HMNs in ocular drug delivery and explores their ocular anatomy and the distribution of formulations following potential HMN administration routes. Additionally, this review focuses on the influence of formulation characteristics (e.g., solution viscosity, particle size), HMN properties (e.g., bore or lumen diameter, MN length), and routes of administration (e.g., periocular transscleral, suprachoroidal, intravitreal) on the ocular distribution of drugs. Overall, this paper highlights the distinctive properties of HMNs, which make them a promising technology for improving drug delivery efficiency, precision, and patient outcomes in the treatment of ocular diseases.
Topics: Needles; Humans; Drug Delivery Systems; Animals; Administration, Ophthalmic; Eye; Pharmaceutical Preparations; Microinjections
PubMed: 38735395
DOI: 10.1016/j.jconrel.2024.05.013 -
Bioengineering (Basel, Switzerland) Sep 2023Over the last two decades, there has been growing interest in assessing corneal biomechanics in different diseases, such as keratoconus, glaucoma, and corneal disorders.... (Review)
Review
Over the last two decades, there has been growing interest in assessing corneal biomechanics in different diseases, such as keratoconus, glaucoma, and corneal disorders. Given the interaction and structural continuity between the cornea and sclera, evaluating corneal biomechanics may give us further insights into the pathogenesis, diagnosis, progression, and management of glaucoma. Therefore, some authorities have recommended baseline evaluations of corneal biomechanics in all glaucoma and glaucoma suspects patients. Currently, two devices (Ocular Response Analyzer and Corneal Visualization Schiempflug Technology) are commercially available for evaluating corneal biomechanics; however, each device reports different parameters, and there is a weak to moderate agreement between the reported parameters. Studies are further limited by the inclusion of glaucoma subjects taking topical prostaglandin analogues, which may alter corneal biomechanics and contribute to contradicting results, lack of proper stratification of patients, and misinterpretation of the results based on factors that are confounded by intraocular pressure changes. This review aims to summarize the recent evidence on corneal biomechanics in glaucoma patients and insights for future studies to address the current limitations of the literature studying corneal biomechanics.
PubMed: 37892838
DOI: 10.3390/bioengineering10101108 -
Ceska a Slovenska Oftalmologie :... 2024To summarize the history and current trends in the use of scleral grafts in ophthalmology. (Review)
Review
AIM
To summarize the history and current trends in the use of scleral grafts in ophthalmology.
MATERIALS AND METHODS
We conducted a review of the literature through the MEDLINE and Cochrane Library databases. The search terms were "sclera", "graft", and "surgery". The search resulted in 1596 articles, of which we evaluated 192 as relevant. The relevant articles were sorted chronologically and according to the method of using scleral grafts, which enabled the development of a review article.
RESULTS
The sclera has been routinely used in ophthalmology since the 1950s in many different indications. Some of these indications have become practically obsolete over time (for example, use in the surgical management of retinal detachment), but a large number still find application today (especially use in glaucoma or oculoplastic surgery, or as a patch for a defect in the sclera or cornea).
CONCLUSION
Even though allogeneic sclera is currently used less frequently in ophthalmology compared to other tissue banking products and the range of its indications has partially narrowed, it remains a useful material due to its availability and properties.
Topics: Humans; Ophthalmology; Sclera; Glaucoma; Retinal Detachment; Cornea
PubMed: 38413226
DOI: 10.31348/2024/11