Displaying publications 21 - 40 of 94 in total

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  1. Antiapoptotic effect of taurine against NMDA-induced retinal excitotoxicity in rats
    Lambuk L, Iezhitsa I, Agarwal R, Bakar NS, Agarwal P, Ismail NM
    Neurotoxicology, 2019 01;70:62-71.
    PMID: 30385388 DOI: 10.1016/j.neuro.2018.10.009
    OBJECTIVE: N-methyl-D-aspartate (NMDA) excitotoxicity has been proposed to mediate apoptosis of retinal ganglion cells (RGCs) in glaucoma. Taurine (TAU) has been shown to have neuroprotective properties, thus we examined anti-apoptotic effect of TAU against retinal damage after NMDA exposure.

    METHODOLOGY: Sprague-Dawley rats were divided into 5 groups of 33 each. Group 1 was administered intravitreally with PBS and group 2 was similarly injected with NMDA (160 nmol). Groups 3, 4 and 5 were injected with TAU (320 nmol) 24 hours before (pre-treatment), in combination (co-treatment) and 24 hours after (post-treatment) NMDA exposure respectively. Seven days after injection, rats were sacrificed; eyes were enucleated, fixed and processed for morphometric analysis, TUNEL and caspase-3 staining. Optic nerve morphology assessment was done using toluidine blue staining. The estimation of BDNF, pro/anti-apoptotic factors (Bax/Bcl-2) and caspase-3 activity in retina was done using ELISA technique.

    RESULTS: Severe degenerative changes were observed in retinae after intravitreal NMDA exposure. The retinal morphology in the TAU pre-treated group appeared more similar to the control retinae and demonstrated a higher number of nuclei than the NMDA group both per 100 μm length (by 1.5-fold, p 

    Matched MeSH terms: Retina/drug effects*; Retina/metabolism; Retina/pathology
  2. Fulltext A Review on the Extraction of Quantitative Retinal Microvascular Image Feature
    Kipli K, Hoque ME, Lim LT, Mahmood MH, Sahari SK, Sapawi R, et al.
    Comput Math Methods Med, 2018;2018:4019538.
    PMID: 30065780 DOI: 10.1155/2018/4019538
    Digital image processing is one of the most widely used computer vision technologies in biomedical engineering. In the present modern ophthalmological practice, biomarkers analysis through digital fundus image processing analysis greatly contributes to vision science. This further facilitates developments in medical imaging, enabling this robust technology to attain extensive scopes in biomedical engineering platform. Various diagnostic techniques are used to analyze retinal microvasculature image to enable geometric features measurements such as vessel tortuosity, branching angles, branching coefficient, vessel diameter, and fractal dimension. These extracted markers or characterized fundus digital image features provide insights and relates quantitative retinal vascular topography abnormalities to various pathologies such as diabetic retinopathy, macular degeneration, hypertensive retinopathy, transient ischemic attack, neovascular glaucoma, and cardiovascular diseases. Apart from that, this noninvasive research tool is automated, allowing it to be used in large-scale screening programs, and all are described in this present review paper. This paper will also review recent research on the image processing-based extraction techniques of the quantitative retinal microvascular feature. It mainly focuses on features associated with the early symptom of transient ischemic attack or sharp stroke.
    Matched MeSH terms: Retina
  3. Fulltext Surgical management of unilateral rhegmatogenous retinal detachment associated with ocular coloboma in a 7-year-old child with Noonan syndrome
    Bastion ML, Qader AM
    BMJ Case Rep, 2011;2011.
    PMID: 22696753 DOI: 10.1136/bcr.02.2011.3889
    The authors would like to present an unusual case of unilateral retinal detachment, phacodonesis, dense cataract and ocular coloboma in a 7-year-old Indian Muslim boy with Noonan syndrome. He underwent lensectomy, 23G pars planar vitrectomy, air fluid exchange, endolaser and silicone oil injection which successfully reattached the retina. His best corrected visual acuity was 6/24 6 months after the surgery and oil removal.
    Matched MeSH terms: Retina/abnormalities*; Retina/surgery; Retinal Detachment/etiology; Retinal Detachment/surgery*
  4. Secretory proteostasis of the retinal pigmented epithelium: Impairment links to age-related macular degeneration
    Paraoan L, Sharif U, Carlsson E, Supharattanasitthi W, Mahmud NM, Kamalden TA, et al.
    Prog Retin Eye Res, 2020 11;79:100859.
    PMID: 32278708 DOI: 10.1016/j.preteyeres.2020.100859
    Secretory proteostasis integrates protein synthesis, processing, folding and trafficking pathways that are essential for efficient cellular secretion. For the retinal pigment epithelium (RPE), secretory proteostasis is of vital importance for the maintenance of the structural and functional integrity of apical (photoreceptors) and basal (Bruch's membrane/choroidal blood supply) sides of the environment it resides in. This integrity is achieved through functions governed by RPE secreted proteins, which include extracellular matrix modelling/remodelling, angiogenesis and immune response modulation. Impaired RPE secretory proteostasis affects not only the extracellular environment, but leads to intracellular protein aggregation and ER-stress with subsequent cell death. Ample recent evidence implicates dysregulated proteostasis as a key factor in the development of age-related macular degeneration (AMD), the leading cause of blindness in the developed world, and research aiming to characterise the roles of various proteins implicated in AMD-associated dysregulated proteostasis unveiled unexpected facets of the mechanisms involved in degenerative pathogenesis. This review analyses cellular processes unveiled by the study of the top 200 transcripts most abundantly expressed by the RPE/choroid in the light of the specialised secretory nature of the RPE. Functional roles of these proteins and the mechanisms of their impaired secretion, due to age and genetic-related causes, are analysed in relation to AMD development. Understanding the importance of RPE secretory proteostasis in relation to maintaining retinal health and how it becomes impaired in disease is of paramount importance for the development and assessment of future therapeutic advancements involving gene and cell therapies.
    Matched MeSH terms: Retina/metabolism*; Retina/pathology; Retinal Pigment Epithelium/metabolism*; Retinal Pigment Epithelium/pathology
  5. 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: Retina/metabolism; Retina/physiology
  6. Fulltext Expression of Endogenous Angiotensin-Converting Enzyme 2 in Human Induced Pluripotent Stem Cell-Derived Retinal Organoids
    Ahmad Mulyadi Lai HI, Chou SJ, Chien Y, Tsai PH, Chien CS, Hsu CC, et al.
    Int J Mol Sci, 2021 Jan 28;22(3).
    PMID: 33525682 DOI: 10.3390/ijms22031320
    Angiotensin-converting enzyme 2 (ACE2) was identified as the main host cell receptor for the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its subsequent infection. In some coronavirus disease 2019 (COVID-19) patients, it has been reported that the nervous tissues and the eyes were also affected. However, evidence supporting that the retina is a target tissue for SARS-CoV-2 infection is still lacking. This present study aimed to investigate whether ACE2 expression plays a role in human retinal neurons during SARS-CoV-2 infection. Human induced pluripotent stem cell (hiPSC)-derived retinal organoids and monolayer cultures derived from dissociated retinal organoids were generated. To validate the potential entry of SARS-CoV-2 infection in the retina, we showed that hiPSC-derived retinal organoids and monolayer cultures endogenously express ACE2 and transmembrane serine protease 2 (TMPRSS2) on the mRNA level. Immunofluorescence staining confirmed the protein expression of ACE2 and TMPRSS2 in retinal organoids and monolayer cultures. Furthermore, using the SARS-CoV-2 pseudovirus spike protein with GFP expression system, we found that retinal organoids and monolayer cultures can potentially be infected by the SARS-CoV-2 pseudovirus. Collectively, our findings highlighted the potential of iPSC-derived retinal organoids as the models for ACE2 receptor-based SARS-CoV-2 infection.
    Matched MeSH terms: Retina/cytology*; Retina/metabolism
  7. Bilateral Norrie's disease in identical twins
    Sukumaran K
    Br J Ophthalmol, 1991 Mar;75(3):179-80.
    PMID: 2012789
    A case of Norrie's disease in an identical twins is reported. No positive family history was obtained. The couple had no other children. The older of the twins died at the age of 9 months of uncertain cause. To the best of my knowledge this is the first case of Norrie's disease reported in Malaysia. And its occurrence in an identical twins is very rare.
    Matched MeSH terms: Retina/abnormalities*; Retina/pathology; Retinal Detachment/congenital; Retinal Detachment/pathology
  8. Fulltext The structural effect of intravitreal Brilliant blue G and Indocyanine green in rats eyes
    Ooi YL, Khang TF, Naidu M, Fong KC
    Eye (Lond), 2013 Mar;27(3):425-31.
    PMID: 23196646 DOI: 10.1038/eye.2012.260
    To compare the potential retinal toxicity of two commercially Brilliant blue G dyes (Brilliant Peel and Ocublue Plus) and Indocyanine green (ICG) at usual clinical concentration.
    Matched MeSH terms: Retina/drug effects*; Retina/pathology; Retinal Ganglion Cells/drug effects; Retinal Ganglion Cells/pathology; Vitreoretinal Surgery
  9. A case report on allopurinol induced crystalline maculopathy
    Cheah CK, Vijaya Singham N, Gun SC
    Int J Rheum Dis, 2017 Dec;20(12):2253-2255.
    PMID: 26864240 DOI: 10.1111/1756-185X.12827
    Matched MeSH terms: Retina/drug effects*; Retina/physiopathology; Retinal Diseases/chemically induced*; Retinal Diseases/diagnosis; Retinal Diseases/physiopathology
  10. Lion's Mane, Hericium erinaceus and Tiger Milk, Lignosus rhinocerotis (Higher Basidiomycetes) Medicinal Mushrooms Stimulate Neurite Outgrowth in Dissociated Cells of Brain, Spinal Cord, and Retina: An In Vitro Study
    Samberkar S, Gandhi S, Naidu M, Wong KH, Raman J, Sabaratnam V
    Int J Med Mushrooms, 2015;17(11):1047-54.
    PMID: 26853959
    Neurodegenerative disease is defined as a deterioration of the nervous system in the intellectual and cognitive capabilities. Statistics show that more than 80-90 million individuals age 65 and above in 2050 may be affected by neurodegenerative conditions like Alzheimer's and Parkinson's disease. Studies have shown that out of 2000 different types of edible and/or medicinal mushrooms, only a few countable mushrooms have been selected until now for neurohealth activity. Hericium erinaceus is one of the well-established medicinal mushrooms for neuronal health. It has been documented for its regenerative capability in peripheral nerve. Another mushroom used as traditional medicine is Lignosus rhinocerotis, which has been used for various illnesses. It has been documented for its neurite outgrowth potential in PC12 cells. Based on the regenerative capabilities of both the mushrooms, priority was given to select them for our study. The aim of this study was to investigate the potential of H. erinaceus and L. rhinocerotis to stimulate neurite outgrowth in dissociated cells of brain, spinal cord, and retina from chick embryo when compared to brain derived neurotrophic factor (BDNF). Neurite outgrowth activity was confirmed by the immu-nofluorescence method in all tissue samples. Treatment with different concentrations of extracts resulted in neuronal differentiation and neuronal elongation. H. erinaceus extract at 50 µg/mL triggered neurite outgrowth at 20.47%, 22.47%, and 21.70% in brain, spinal cord, and retinal cells. L. rhinocerotis sclerotium extract at 50 µg/mL induced maximum neurite outgrowth of 20.77% and 24.73% in brain and spinal cord, whereas 20.77% of neurite outgrowth was observed in retinal cells at 25 µg/mL, respectively.
    Matched MeSH terms: Retina/cytology; Retina/drug effects*
  11. Age-related rarefaction in retinal vasculature is not linear
    Che Azemin MZ, Ab Hamid F, Aminuddin A, Wang JJ, Kawasaki R, Kumar DK
    Exp Eye Res, 2013 Nov;116:355-358.
    PMID: 24512773 DOI: 10.1016/j.exer.2013.10.010
    The fractal dimension is a global measure of complexity and is useful for quantifying anatomical structures, including the retinal vascular network. A previous study found a linear declining trend with aging on the retinal vascular fractal dimension (DF); however, it was limited to the older population (49 years and older). This study aimed to investigate the possible models of the fractal dimension changes from young to old subjects (10-73 years). A total of 215 right-eye retinal samples, including those of 119 (55%) women and 96 (45%) men, were selected. The retinal vessels were segmented using computer-assisted software, and non-vessel fragments were deleted. The fractal dimension was measured based on the log-log plot of the number of grids versus the size. The retinal vascular DF was analyzed to determine changes with increasing age. Finally, the data were fitted to three polynomial models. All three models are statistically significant (Linear: R2 = 0.1270, 213 d.f., p 
    Matched MeSH terms: Retina; Retinal Vessels
  12. Kearns-Sayre syndrome: An unusual ophthalmic presentation
    Ahmad SS, Ghani SA
    Oman J Ophthalmol, 2012 May;5(2):115-7.
    PMID: 22993469
    Kearns-Sayre syndrome (KSS) belongs to the group of neuromuscular disorders known as mitochondrial encephalomyopathies. It has characteristic syndromal features, which include: chronic progressive external ophthalmoplegia, bilateral atypical pigmentary retinopathy, and cardiac conduction abnormalities. So far, only a single case has been reported where a patient with KSS had a normal retina. Herein, we report this extremely rare variant of KSS, which not only presented later than the normal age of presentation, but also had minimal pigmentary retinopathy.
    Matched MeSH terms: Retina
  13. Fulltext Intracameral injection of ranibizumab caused regression of iris neovascularisation and clearance of hyphaema in a non-diabetic patient with ischaemic remnant retinal flap in a silicone filled eye
    Bastion ML
    BMJ Case Rep, 2010;2010.
    PMID: 22242074 DOI: 10.1136/bcr.10.2009.2398
    The use of 0.5 mg/0.05 ml of ranibizumab intracamerally, to induce regression of iris neovascularisation in a non-diabetic patient, is reported. A 55-year-old Malay man presented with left eye rubeosis and hyphaema secondary to ischaemic remnant retinal flap in his silicone filled pseudophakic eye. Regression of rubeosis and resolution of hyphaema was noted within 4 days of injection of intracameral ranibizumab, allowing repeat vitrectomy to be performed without much bleeding, thus facilitating removal of his intraocular lens and laser to remaining flap. One month postoperatively he remained comfortable with counting fingers vision similar to the pre-hyphaema period.
    Matched MeSH terms: Retina
  14. Fulltext Short-term postoperative perfluoro-n-octane tamponade for pediatric recurrent retinal detachment
    Ling KP, Wu AL, Lai CC, Wu WC
    Taiwan J Ophthalmol, 2019 1 15;8(4):249-252.
    PMID: 30637197 DOI: 10.4103/tjo.tjo_100_18
    We report a case with multiple recurrences of retinal detachment (RD) with severe proliferative vitreoretinopathy in a 12-year-old child who underwent vitrectomy using a heavy liquid perfluoro-n-octane (PFO) as a short-term postoperative tamponade. He had an encircling band and three vitrectomies with gas, followed by silicone oil tamponade for retinal redetachment prior to the use of PFO as a short-term tamponade. Short-term PFO tamponade was used in which inferior retinal reattachment was considered to be difficult with conventional gas or silicone oil tamponade, especially in regard to proper postoperative posturing. The PFO was left in the eye for 1 week, and the retina remained reattached after removal of the PFO which was replaced with silicone oil tamponade in this case. PFO appears feasible and tolerable as a short-term postoperative tamponade in the management of complex pediatric RD.
    Matched MeSH terms: Retina; Retinal Detachment
  15. Fulltext Recurrent orbital cellulitis secondary to the ‘forgotten’ scleral buckle: a case report
    Hor, S.M., Noor Aniah, A., Mushawiahti, M., Mushawiahti, M., Bastion, M.L.C.
    Journal of Surgical Academia, 2017;7(2):49-52.
    MyJurnal
    Scleral buckle placement is a well-established technique for the treatment of primary rhegmatogenous retinal
    detachment. Complications associated with scleral buckle are uncommon and its presentations can be vary. We
    report a case of recurrent orbital cellulitis with anterior segment ischemia following a forgotten episode of previous
    scleral buckling surgery, presenting with blurring of vision, redness and swelling of the lids. The presence of scleral
    buckle was detected by detailed examination and confirmed by orbital imaging. Orbital infection and rubeosis iridis
    were successfully treated with scleral buckle removal, intravenous antibiotics and intracameral ranibizumab.
    However, the retinal detachment recurred and the visual acuity deteriorated to light perception. There was no further
    intervention as the family declined in view of her old age. In cases of recurrent orbital infection, detailed clinical
    examination is important to look for evidence of ocular prostheses as a source of infection. Orbital imaging is an
    adjunct for making the diagnosis especially in cases where history is unreliable. Anterior segment ischemia due to
    scleral buckle responds well to buckle removal with ranibizumab injection.
    Matched MeSH terms: Retina; Retinal Detachment
  16. Fulltext An introduction to DARC technology
    Ahmad SS
    Saudi J Ophthalmol, 2017 Jan-Mar;31(1):38-41.
    PMID: 28337061 DOI: 10.1016/j.sjopt.2016.08.001
    Glaucoma is a multi-factorial neurodegenerative disorder. The common denominator in all types of glaucomas is retinal ganglion cell death through apoptosis. However, this cellular demise in glaucoma is detected late by structural or functional analyses. There can be a 10-year delay prior to the appearance of visual field defects and pre-perimetric glaucoma is an issue still being addressed. However, a new cutting-edge technology called detection of apoptosing retinal cells (DARC) is being developed. This technique is capable of non-invasive, real-time visualization of apoptotic changes at the cellular level. It can detect glaucomatous cell damage at a very early stage, at the moment apoptosis starts, and thus management can be initiated even prior to development of visual field changes. In future, this technique will also be able to provide conclusive evidence of the effectiveness of treatment protocol and the need for any modifications which may be required. This article aims to provide a concise review of DARC technology.
    Matched MeSH terms: Retina; Retinal Ganglion Cells
  17. Fulltext Connexin Hemichannel Block Using Orally Delivered Tonabersat Improves Outcomes in Animal Models of Retinal Disease
    Mat Nor MN, Rupenthal ID, Green CR, Acosta ML
    Neurotherapeutics, 2020 Jan;17(1):371-387.
    PMID: 31637594 DOI: 10.1007/s13311-019-00786-5
    Increased Connexin43 hemichannel opening is associated with inflammasome pathway activation and inflammation in a range of pathologies including ocular disorders, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). In this study, the effect on retinal function and morphology of clinically safe doses of orally delivered tonabersat, a small molecule connexin hemichannel blocker, was investigated in the light-damaged retina animal model of dry AMD and in a spontaneous rat model of DR. Clinical parameters (fundus imaging, optical coherence tomography (OCT), and electroretinography) and inflammatory markers (immunohistochemistry for Iba-1 microglial marker, astrocyte marker glial fibrillary acidic protein, and Connexin43 protein expression) were assessed. Tonabersat treatment reduced inflammation in the retina in parallel with preservation of retinal photoreceptor function when assessed up to 3 months post light damage in the dry AMD model. In the DR model, clinical signs, including the presence of aneurysms confirmed using Evans blue dye perfusion, were reduced after daily tonabersat treatment for 2 weeks. Inflammation was also reduced and retinal electrical function restored. Tonabersat regulates assembly of the inflammasome (NLRP3) through Connexin43 hemichannel block, with the potential to reduce inflammation, restore vascular integrity and improve anatomical along with some functional outcomes in retinal disease.
    Matched MeSH terms: Retina/drug effects*; Retina/metabolism; Retina/pathology; Retinal Diseases/complications; Retinal Diseases/drug therapy*; Retinal Diseases/pathology
  18. Fulltext Tonabersat Prevents Inflammatory Damage in the Central Nervous System by Blocking Connexin43 Hemichannels
    Kim Y, Griffin JM, Nor MNM, Zhang J, Freestone PS, Danesh-Meyer HV, et al.
    Neurotherapeutics, 2017 Oct;14(4):1148-1165.
    PMID: 28560708 DOI: 10.1007/s13311-017-0536-9
    The cis benzopyran compound tonabersat (SB-220453) has previously been reported to inhibit connexin26 expression in the brain by attenuating the p38-mitogen-activated protein kinase pathway. We show here that tonabersat directly inhibits connexin43 hemichannel opening. Connexin43 hemichannels have been called "pathological pores" based upon their role in secondary lesion spread, edema, inflammation, and neuronal loss following central nervous system injuries, as well as in chronic inflammatory disease. Both connexin43 hemichannels and pannexin channels released adenosine triphosphate (ATP) during ischemia in an in vitro ischemia model, but only connexin43 hemichannels contributed to ATP release during reperfusion. Tonabersat inhibited connexin43 hemichannel-mediated ATP release during both ischemia and reperfusion phases, with direct channel block confirmed using electrophysiology. Tonabersat also reduced connexin43 gap junction coupling in vitro, but only at higher concentrations, with junctional plaques internalized and degraded via the lysosomal pathway. Systemic delivery of tonabersat in a rat bright-light retinal damage model (a model for dry age-related macular degeneration) resulted in significantly improved functional outcomes assessed using electroretinography. Tonabersat also prevented thinning of the retina, especially the outer nuclear layer and choroid, assessed using optical coherence tomography. We conclude that tonabersat, already given orally to over 1000 humans in clinical trials (as a potential treatment for, and prophylactic treatment of, migraine because it was thought to inhibit cortical spreading depression), is a connexin hemichannel inhibitor and may have the potential to be a novel treatment of central nervous system injury and chronic neuroinflammatory disease.
    Matched MeSH terms: Retina/drug effects; Retina/pathology; Retina/physiopathology
  19. Fulltext Zone specific fractal dimension of retinal images as predictor of stroke incidence
    Aliahmad B, Kumar DK, Hao H, Unnikrishnan P, Che Azemin MZ, Kawasaki R, et al.
    ScientificWorldJournal, 2014;2014:467462.
    PMID: 25485298 DOI: 10.1155/2014/467462
    Fractal dimensions (FDs) are frequently used for summarizing the complexity of retinal vascular. However, previous techniques on this topic were not zone specific. A new methodology to measure FD of a specific zone in retinal images has been developed and tested as a marker for stroke prediction. Higuchi's fractal dimension was measured in circumferential direction (FDC) with respect to optic disk (OD), in three concentric regions between OD boundary and 1.5 OD diameter from its margin. The significance of its association with future episode of stroke event was tested using the Blue Mountain Eye Study (BMES) database and compared against spectrum fractal dimension (SFD) and box-counting (BC) dimension. Kruskal-Wallis analysis revealed FDC as a better predictor of stroke (H = 5.80, P = 0.016, α = 0.05) compared with SFD (H = 0.51, P = 0.475, α = 0.05) and BC (H = 0.41, P = 0.520, α = 0.05) with overall lower median value for the cases compared to the control group. This work has shown that there is a significant association between zone specific FDC of eye fundus images with future episode of stroke while this difference is not significant when other FD methods are employed.
    Matched MeSH terms: Retina/pathology*; Retinal Vessels/pathology
  20. Combined large radial retinotomy and circumferential retinectomy in the management of advanced proliferative vitreoretinopathy
    Lim AK, Alexander SM, Lim KS
    Retina, 2009 Jan;29(1):112-6.
    PMID: 18784619 DOI: 10.1097/IAE.0b013e318187f14a
    Matched MeSH terms: Retina/surgery*; Retinal Detachment/surgery*
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