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Fulltext Central corneal thickness and intraocular pressure in Malay children

Heidary F, Gharebaghi R, Wan Hitam WH, Naing NN, Wan-Arfah N, Shatriah I

PLoS One, 2011;6(10):e25208.

PMID: 21998644 DOI: 10.1371/journal.pone.0025208

To determine the mean values for central corneal thickness (CCT) and intraocular pressure (IOP) and the relationship between these values, in healthy Malay children to serve as reference values in diagnosis and treatment.

Matched MeSH terms: Cornea/physiology

Histomorphometric profile of the corneal response to short-term reverse-geometry orthokeratology lens wear in primate corneas: a pilot study

Cheah PS, Norhani M, Bariah MA, Myint M, Lye MS, Azian AL

Cornea, 2008 May;27(4):461-70.

PMID: 18434851 DOI: 10.1097/ICO.0b013e318165642c

To investigate the histological changes in primate cornea induced by short-term overnight orthokeratology (OK).

Matched MeSH terms: Cornea/physiology*

Fulltext Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes

Zouache MA, Eames I, Samsudin A

PLoS One, 2016;11(3):e0151490.

PMID: 26990431 DOI: 10.1371/journal.pone.0151490

In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.

Matched MeSH terms: Cornea/physiology

Liposomes in topical ophthalmic drug delivery: an update

Agarwal R, Iezhitsa I, Agarwal P, Abdul Nasir NA, Razali N, Alyautdin R, et al.

Drug Deliv, 2016 May;23(4):1075-91.

PMID: 25116511 DOI: 10.3109/10717544.2014.943336

Topical route of administration is the most commonly used method for the treatment of ophthalmic diseases. However, presence of several layers of permeation barriers starting from the tear film till the inner layers of cornea make it difficult to achieve the therapeutic concentrations in the target tissue within the eye. In order to circumvent these barriers and to provide sustained and targeted drug delivery, tremendous advances have been made in developing efficient and safe drug delivery systems. Liposomes due to their unique structure prove to be extremely beneficial drug carriers as they can entrap both the hydrophilic and hydrophobic drugs. The conventional liposomes had several drawbacks particularly their tendency to aggregate, the instability and leakage of entrapped drug and susceptibility to phagocytosis. Due to this reason, for a long time, liposomes as drug delivery systems did not attract much attention of researchers and clinicians. However, over recent years development of new generation liposomes has opened up new approaches for targeted and sustained drug delivery using liposomes and has rejuvenated the interest of researchers in this field. In this review we present a summary of current literature to understand the anatomical and physiological limitation in achieving adequate ocular bioavailability of topically applied drugs and utility of liposomes in overcoming these limitations. The recent developments related to new generation liposomes are discussed.

Matched MeSH terms: Cornea/physiology*

Scanning electron microscopy of cornea re-epithelization after transplanted with bilayered corneal construct

Masrudin SS, Ghafar NA, Saidi M, Aminuddin BS, Rahmat A, Ruszymah BH, et al.

Med J Malaysia, 2008 Jul;63 Suppl A:109-10.

PMID: 19025009

The present work was to determine the development and re-epithelization of bilayered corneal construct (BCC) in vitro and in vivo using scanning electron microscopy (SEM). The in vitro BCC was transplanted to the rabbit's eye and after 90 days the BCC was harvested and analyzed. The corneas were processed for morphology studies. The result indicates that the BICC that was transplanted for 90 days showed good development and re-epithelization of epithelial layer similar to the normal cornea.

Matched MeSH terms: Cornea/physiology*

Critical review: effects of optical defocus on refractive development and ocular growth and relation to accommodation

Chung KM

Optom Vis Sci, 1993 Mar;70(3):228-33.

PMID: 8483585

Studies of optical defocus on refractive development and ocular growth in animals are presented and discussed in relation to the accommodation hypothesis. None of these studies fully support the accommodation hypothesis. The problems encountered in these studies are also discussed.

Matched MeSH terms: Cornea/physiology

Fulltext Non-invasive tear break-up time in normal Malays

Mohidin N, Bay TC, Yap M

Clin Exp Optom, 2002 Jan;85(1):37-41.

PMID: 11952394 DOI: 10.1111/j.1444-0938.2002.tb03070.x

Tear stability in normal Malays with consideration of gender and age has not been reported. In this study, we measured tear stability in normal Malays using the non-invasive tear break-up time (NIBUT).

Matched MeSH terms: Cornea/physiology*

Fulltext Neuroprotective Effects and Therapeutic Potential of Transcorneal Electrical Stimulation for Depression

Yu WS, Kwon SH, Agadagba SK, Chan LL, Wong KH, Lim LW

Cells, 2021 09 21;10(9).

PMID: 34572141 DOI: 10.3390/cells10092492

Transcorneal electrical stimulation (TES) has emerged as a non-invasive neuromodulation approach that exerts neuroprotection via diverse mechanisms, including neurotrophic, neuroplastic, anti-inflammatory, anti-apoptotic, anti-glutamatergic, and vasodilation mechanisms. Although current studies of TES have mainly focused on its applications in ophthalmology, several lines of evidence point towards its putative use in treating depression. Apart from stimulating visual-related structures and promoting visual restoration, TES has also been shown to activate brain regions that are involved in mood alterations and can induce antidepressant-like behaviour in animals. The beneficial effects of TES in depression were further supported by its shared mechanisms with FDA-approved antidepressant treatments, including its neuroprotective properties against apoptosis and inflammation, and its ability to enhance the neurotrophic expression. This article critically reviews the current findings on the neuroprotective effects of TES and provides evidence to support our hypothesis that TES possesses antidepressant effects.

Matched MeSH terms: Cornea/physiology*

Corneal regeneration by induced human buccal mucosa cultivated on an amniotic membrane following alkaline injury

Man RC, Yong TK, Hwei NM, Halim WHWA, Zahidin AZM, Ramli R, et al.

Mol Vis, 2017;23:810-822.

PMID: 29225457

Various clinical disorders and injuries, such as chemical, thermal, or mechanical injuries, may lead to corneal loss that results in blindness. PURPOSE: The aims of this study were to differentiate human buccal mucosa (BMuc) into corneal epithelial-like cells, to fabricate engineered corneal tissue using buccal mucosal epithelial cells, and to reconstruct a damaged corneal epithelium in a nude rat model.

Methods: BMuc were subjected to 10 d of induction factors to investigate the potential of cells to differentiate into corneal lineages.

Results: Corneal stem cell markers β1-integrin, C/EBPδ, ABCG2, p63, and CK3 were upregulated in the gene expression analysis in induced BMuc, whereas CK3 and p63 showed significant protein expression in induced BMuc compared to the uninduced cells. BMuc were then left to reach 80% confluency after differential trypsinization. The cells were harvested and cultivated on a commercially available untreated air-dried amniotic membrane (AM) in a Transwell system in induction medium. The corneal constructs were fabricated and then implanted into damaged rat corneas for up to 8 weeks. A significant improvement was detected in the treatment group at 8 weeks post-implantation, as revealed by slit lamp biomicroscopy analysis. The structure and thickness of the corneal layer were also analyzed using histological staining and time-domain optical coherence tomography scans and were found to resemble a native corneal layer. The protein expression for CK3 and p63 were continuously detected throughout the corneal epithelial layer in the corneal construct.

Conclusions: In conclusion, human BMuc can be induced to express a corneal epithelial-like phenotype. The addition of BMuc improves corneal clarity, prevents vascularization, increases corneal thickness and stromal alignment, and appears to have no adverse effect on the host after implantation.

Matched MeSH terms: Cornea/physiology*

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