Displaying publications 1 - 20 of 94 in total

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  1. Maheshwari S, Kanhangad V, Pachori RB, Bhandary SV, Acharya UR
    Comput Biol Med, 2019 Feb;105:72-80.
    PMID: 30590290 DOI: 10.1016/j.compbiomed.2018.11.028
    BACKGROUND AND OBJECTIVE: Glaucoma is a ocular disorder which causes irreversible damage to the retinal nerve fibers. The diagnosis of glaucoma is important as it may help to slow down the progression. The available clinical methods and imaging techniques are manual and require skilled supervision. For the purpose of mass screening, an automated system is needed for glaucoma diagnosis which is fast, accurate, and helps in reducing the burden on experts.

    METHODS: In this work, we present a bit-plane slicing (BPS) and local binary pattern (LBP) based novel approach for glaucoma diagnosis. Firstly, our approach separates the red (R), green (G), and blue (B) channels from the input color fundus image and splits the channels into bit planes. Secondly, we extract LBP based statistical features from each of the bit planes of the individual channels. Thirdly, these features from the individual channels are fed separately to three different support vector machines (SVMs) for classification. Finally, the decisions from the individual SVMs are fused at the decision level to classify the input fundus image into normal or glaucoma class.

    RESULTS: Our experimental results suggest that the proposed approach is effective in discriminating normal and glaucoma cases with an accuracy of 99.30% using 10-fold cross validation.

    CONCLUSIONS: The developed system is ready to be tested on large and diverse databases and can assist the ophthalmologists in their daily screening to confirm their diagnosis, thereby increasing accuracy of diagnosis.

    Matched MeSH terms: Retina
  2. Mat Nor MN, Rupenthal ID, Green CR, Acosta ML
    Int J Mol Sci, 2021 Feb 10;22(4).
    PMID: 33578721 DOI: 10.3390/ijms22041755
    Dysregulation of retinal function in the early stages of light-induced retinal degeneration involves pannexins and connexins. These two types of proteins may contribute to channels that release ATP, leading to activation of the inflammasome pathway, spread of inflammation and retinal dysfunction. However, the effect of pannexin channel block alone or block of both pannexin channels and connexin hemichannels in parallel on retinal activity in vivo is unknown. In this study, the pannexin channel blocker probenecid and the connexin hemichannel blocker tonabersat were used in the light-damaged rat retina. Retinal function was evaluated using electroretinography (ERG), retinal structure was analyzed using optical coherence tomography (OCT) imaging and the tissue response to light-induced injury was assessed immunohistochemically with antibodies against glial fibrillary acidic protein (GFAP), Ionized calcium binding adaptor molecule 1 (Iba-1) and Connexin43 (Cx43). Probenecid did not further enhance the therapeutic effect of connexin hemichannel block in this model, but on its own improved activity of certain inner retina neurons. The therapeutic benefit of blocking connexin hemichannels was further evaluated by comparing these data against results from our previously published studies that also used the light-damaged rat retina model. The analysis showed that treatment with tonabersat alone was better than probenecid alone at restoring retinal function in the light-damaged retina model. The results assist in the interpretation of the differential action of connexin hemichannel and pannexin channel therapeutics for potential treatment of retinal diseases.
    Matched MeSH terms: Retina/drug effects*; Retina/pathology; Retina/radiation effects; Retinal Diseases/drug therapy*; Retinal Diseases/etiology; Retinal Diseases/pathology
  3. Mat Nor N, Guo CX, Rupenthal ID, Chen YS, Green CR, Acosta ML
    Invest Ophthalmol Vis Sci, 2018 07 02;59(8):3682-3693.
    PMID: 30029255 DOI: 10.1167/iovs.17-22829
    Purpose: To evaluate the long-term effect on inflammation and inflammasome activation of intravitreally delivered connexin43 mimetic peptide (Cx43MP) in saline or incorporated within nanoparticles (NPs) for the treatment of the light-damaged rat eye.

    Methods: Light-induced damage to the retina was created by exposure of adult albino Sprague-Dawley rats to intense light for 24 hours. A single dose of Cx43MP, Cx43MP-NPs, or saline was injected intravitreally at 2 hours after onset of light damage. Fluorescein isothiocyanate (FITC)-labelled Cx43MP-NPs were intravitreally injected to confirm delivery into the retina. Electroretinogram (ERG) recordings were performed at 24 hours, 1 week, and 2 weeks post cessation of light damage. The retinal and choroidal layers were analyzed in vivo using optical coherence tomography (OCT) and immunohistochemistry was performed on harvested tissues using glial fibrillary acidic protein (GFAP), leukocyte common antigen (CD45), and Cx43 antibodies.

    Results: FITC was visualized 30 minutes after injection in the ganglion cell layer and in the choroid. Cx43MP and Cx43MP-NP treatments improved a-wave and b-wave function of the ERG compared with saline-injected eyes at 1 week and 2 weeks post treatment, and prevented photoreceptor loss by 2 weeks post treatment. Inflammation was also reduced and this was in parallel with downregulation of Cx43 expression.

    Conclusions: The slow release of Cx43MP incorporated into NPs is more effective at treating retinal injury than a single dose of native Cx43MP in solution by reducing inflammation and maintaining both retinal structure and function. This NP preparation has clinical relevance as it reduces possible ocular complications associated with repeated intravitreal injections.

    Matched MeSH terms: Retina/metabolism; Retina/pathology*; Retinal Diseases/drug therapy*; Retinal Diseases/metabolism; Retinal Diseases/pathology
  4. 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
  5. Sadikan MZ, Abdul Nasir NA, Lambuk L, Mohamud R, Reshidan NH, Low E, et al.
    BMC Ophthalmol, 2023 Oct 19;23(1):421.
    PMID: 37858128 DOI: 10.1186/s12886-023-03155-1
    Diabetic retinopathy (DR), one of the leading causes of visual impairment and blindness worldwide, is one of the major microvascular complications in diabetes mellitus (DM). Globally, DR prevalence among DM patients is 25%, and 6% have vision-threatening problems among them. With the higher incidence of DM globally, more DR cases are expected to be seen in the future. In order to comprehend the pathophysiological mechanism of DR in humans and discover potential novel substances for the treatment of DR, investigations are typically conducted using various experimental models. Among the experimental models, in vivo models have contributed significantly to understanding DR pathogenesis. There are several types of in vivo models for DR research, which include chemical-induced, surgical-induced, diet-induced, and genetic models. Similarly, for the in vitro models, there are several cell types that are utilised in DR research, such as retinal endothelial cells, Müller cells, and glial cells. With the advancement of DR research, it is essential to have a comprehensive update on the various experimental models utilised to mimic DR environment. This review provides the update on the in vitro, in vivo, and ex vivo models used in DR research, focusing on their features, advantages, and limitations.
    Matched MeSH terms: Retina/pathology
  6. 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
  7. Neoh YL, Neoh PF, Salleh A, Yusof ZB, Gurusamy B, Ahmad Tajudin LS
    Ann Acad Med Singap, 2018 06;47(6):226-229.
    PMID: 30019068
    Matched MeSH terms: Retina/pathology*
  8. Mohd Khalid MK, Yakob Y, Md Yasin R, Wee Teik K, Siew CG, Rahmat J, et al.
    Mol Vis, 2015;21:1185-90.
    PMID: 26539030
    The availability of molecular genetic testing for retinoblastoma (RB) in Malaysia has enabled patients with a heritable predisposition to the disease to be identified, which thus improves the clinical management of these patients and their families. In this paper, we presented our strategy for performing molecular genetic testing of the RB1 gene and the findings from our first 2 years of starting this service.
    Matched MeSH terms: Retina/metabolism; Retina/pathology; Retinal Neoplasms/ethnology; Retinal Neoplasms/genetics*; Retinal Neoplasms/pathology
  9. Ramli R, Idris MYI, Hasikin K, A Karim NK, Abdul Wahab AW, Ahmedy I, et al.
    J Healthc Eng, 2017;2017:1489524.
    PMID: 29204257 DOI: 10.1155/2017/1489524
    Retinal image registration is important to assist diagnosis and monitor retinal diseases, such as diabetic retinopathy and glaucoma. However, registering retinal images for various registration applications requires the detection and distribution of feature points on the low-quality region that consists of vessels of varying contrast and sizes. A recent feature detector known as Saddle detects feature points on vessels that are poorly distributed and densely positioned on strong contrast vessels. Therefore, we propose a multiresolution difference of Gaussian pyramid with Saddle detector (D-Saddle) to detect feature points on the low-quality region that consists of vessels with varying contrast and sizes. D-Saddle is tested on Fundus Image Registration (FIRE) Dataset that consists of 134 retinal image pairs. Experimental results show that D-Saddle successfully registered 43% of retinal image pairs with average registration accuracy of 2.329 pixels while a lower success rate is observed in other four state-of-the-art retinal image registration methods GDB-ICP (28%), Harris-PIIFD (4%), H-M (16%), and Saddle (16%). Furthermore, the registration accuracy of D-Saddle has the weakest correlation (Spearman) with the intensity uniformity metric among all methods. Finally, the paired t-test shows that D-Saddle significantly improved the overall registration accuracy of the original Saddle.
    Matched MeSH terms: Retina
  10. Munira Y, Zunaina E, Azhany Y
    Int Med Case Rep J, 2013;6:37-9.
    PMID: 23966803 DOI: 10.2147/IMCRJ.S47769
    A 15-year-old boy presented with painless progressive blurring of vision in the right eye for 1 year in duration. His visual acuity in the right eye was hand movement. The right fundus showed presence of extensive subretinal exudates at the posterior pole and a retinal macrocyst at the temporal periphery. It was associated with exudative retinal detachment at the inferior periphery of the retina. Fundus angiography revealed telangiectatic retinal vessels at the superotemporal retina. Based on clinical and angiographic findings, a diagnosis of Coats disease was made. He was treated with retinal laser photocoagulation. There was resolution of the exudative retinal detachment, reduction of subretinal exudates, and regression of the retinal macrocyst with improvement of visual acuity to 1/60 post-laser therapy.
    Matched MeSH terms: Retina; Retinal Detachment; Retinal Vessels; Retinal Telangiectasis
  11. Yong KC, Kah TA, Ghee YT, Siang LC, Bastion ML
    BMC Ophthalmol, 2011;11:24.
    PMID: 21867521 DOI: 10.1186/1471-2415-11-24
    To report a case of branch retinal vein occlusion in a young adult with bipolar mood disorder treated with quetiapine fumarate.
    Matched MeSH terms: Retina/drug effects; Retina/pathology*; Retinal Vein Occlusion/chemically induced*; Retinal Vein Occlusion/diagnosis
  12. 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
  13. Hor, S.M., Noor Aniah, A., Mushawiahti, M., Mushawiahti, M., Bastion, M.L.C.
    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
  14. Pee XK, Low A, Ab Kahar MEPI, Mohamed SO, Chong YJ
    BMC Ophthalmol, 2023 Nov 07;23(1):444.
    PMID: 37932684 DOI: 10.1186/s12886-023-03186-8
    BACKGROUND: To report a rare case of pulmonary and ocular complications with visual loss due to bilateral Purtscher-like retinopathy and paracentral acute middle maculopathy (PAMM) following a hyaluronic acid (HA) filler injection to the breast. Systemic and visual recovery was attained following corticosteroid therapy.

    CASE PRESENTATION: A 27-year-old lady presented with painless blurring of vision in both eyes for 2 weeks following hyaluronic acid breast filler injections by a non-medical practitioner. She was initially admitted to the medical ward for diffuse alveolar haemorrhage and altered sensorium. The presenting visual acuity was counting fingers in both eyes. Bilateral dilated fundus examination showed hyperaemic discs, concentric rim of retinal whitening around macula with patches of polygonal-shaped retinal whitening, generalised cotton-wool spots, tortuous veins, and flame-shaped haemorrhages. Spectral-domain optical coherence tomography (SD-OCT) macula revealed hyper-reflective bands at the inner nuclear layer (INL). Fluorescein angiography demonstrated hot discs, delayed arm-to-retina time, arterial filling, and arterio-venous transit time with staining of the vessels at the posterior pole. She was managed with a tapering dose of systemic corticosteroids. The visual acuity improved to 6/12 over 8 weeks with significant anatomical and functional improvement. Dilated fundus examination showed resolution of initial funduscopy findings. The hyper-reflective bands on the OCT had resolved with subsequent thinning of the INL and disorganisation of retinal inner layers.

    CONCLUSION: Filler injections are in increasing demand and are frequently being performed by non-medical practitioners. Visual loss from non-facial HA fillers is rare. Inadvertent entry of HA into a blood vessel may potentially cause systemic and sight-threatening ocular complications. Good anatomical knowledge and proper injection technique are vital in preventing this unfortunate sequela. There are limited reports on successful visual recovery following various treatment approaches and we hope this case provides valuable insights.

    Matched MeSH terms: Retina
  15. Chung KM
    Optom Vis Sci, 1999 Feb;76(2):121-6.
    PMID: 10082059
    The clinical significance of fundus magnification produced during direct ophthalmoscopy of the corrected eye has not been fully established. Based on paraxial ray tracing, fundus magnification (M) can be defined by a simple equation, M = (K'/4) x (Fs/K), where K' is the dioptric axial power of the eye, Fs is the correcting thin lens power and K is the ocular ametropia. Refractive myopes produce greater fundus magnification than axial myopes, whereas refractive hyperopes produce lower fundus magnification than axial hyperopes. If we assume 15 x fundus magnification as our standard magnification for an emmetropic reduced eye, then wearing glasses or putting the focusing lens at or close to the anterior focus of the eye is able to achieve the standard magnification for axial myope and axial hyperope, whereas wearing contact lenses is able to achieve the standard magnification for refractive myope and refractive hyperope. Vertex distance has greater influence on fundus magnification produced during direct ophthalmoscopy than other funduscopic techniques. In conclusion, the newly defined formula has clinical applications during direct ophthalmoscopy.
    Matched MeSH terms: Retina/pathology*
  16. Agarwal P, Wong YH, Das Gupta E, Agarwal R, Livingstone BI, Ramamurthy S, et al.
    Cutan Ocul Toxicol, 2015;34(3):179-84.
    PMID: 25068998 DOI: 10.3109/15569527.2014.938751
    BACKGROUND: Hydroxychloroquine (HCQ) is widely used for long-term treatment of autoimmune diseases such as rheumatoid arthritis. However, its long-term use is known to be associated with visual changes due to retinal damage. Retinal damage associated with long-term HCQ therapy is preventable if the drug is discontinued early when the patients are still asymptomatic. In view of contrasting reports from previous studies, we investigated the association of prolonged HCQ therapy with retinal thickness in macular area.
    METHODS: This study included 48 patients on long-term HCQ therapy and 38 healthy controls. All subjects underwent examination for corrected visual acuity, fundus photography, visual fields and SD-OCT for retinal thickness.
    RESULTS: Visual acuity, visual fields, fundus photography and SD-OCT did not reveal changes consistent with diagnosis of established HCQ retinopathy in any of the subjects from HCQ group. Retinal thickness in central, parafoveal and perifoveal areas did not show significant differences between HCQ and control groups. However, we observed negative correlation between cumulative dose and retinal thickness in the parafoveal (p = 0.003) and perifoveal areas (p = 0.019) but not in the central area.
    CONCLUSIONS: Correlation of cumulative dose with retinal thickness in parafoveal and perifoveal areas and not the central area is in accordance with the late appearance of HCQ-induced bull's eye retinopathy. Hence screening of asymptomatic patients using OCT seems to be of great importance for early detection of retinal changes.
    KEYWORDS: Cumulative dose; OCT; hydroxychloroquine; retinal thickness
    Matched MeSH terms: Retina/drug effects*; Retina/pathology
  17. Eu-sen VO
    Med J Malaya, 1969 Sep;24(1):18-20.
    PMID: 4243836
    Matched MeSH terms: Retina*
  18. Mohd Aznan MA, Khairidzan MK, Razman MR, Fa’iza A
    MyJurnal
    Introduction: Diabetic retinopathy (DR) is one of the commonest complications of diabetes mellitus. This study was to determine the prevalence of DR and its association with chronic kidney disease (CKD), high HbA1c and dyslipidemia among diabetic patients in government primary care clinics.
    Materials and Methods: A cross sectional study was carried out. The respondents were selected from diabetic registry at two government primary care clinics in Kuantan, Pahang via stratified random sampling method during the study period from May 2010 to April 2011. The respondents were interviewed and assessed clinically using a structured questionnaire. Retinal examination was performed by accredited staff using non-mydratic retinal imaging and DR was classified according to the International Clinical Diabetic Retinopathy Disease Severity Scale.
    Results: Out of 400 respondents, 58.8% were diagnosed with diabetes less than 5 years and 51.0% had uncontrolled blood pressure (>130/80 mmHg). The prevalence of DR and maculopathy were 33.5% and of 17.8% respectively. Most of these patients (22.3%) had mild non-proliferative DR. DR patients had higher percentages CKD (17.9% vs. 6.8%; p<0.001) and a higher mean of HbA1C (8.69 vs. 8.11; p=0.015) compared to non-DR patients. The study revealed that DR was independently associated with CKD {OR: 3.46, 95% CI (1.76, 6.80)} and high HbA1c {OR: 1.12, 95% CI (1.02, 1.23)}. Those with dyslipidemia however, has 39% less risk of DR {OR: 0.61, 95% CI (0.39, 0.94)}.
    Conclusion: This study showed that diabetic patients with CKD and high HbA1c have greater risks to develop DR but has protective risk with dyslipidemia.
    KEYWORDS: diabetic retinopathy (DR), non-mydratic retinal camera, primary care clinic
    Matched MeSH terms: Retina; Retinal Diseases
  19. 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
  20. Norshamsiah, M.D., Wan Haslina Wah, Kok, H.S., Sharifa Ezat, W.P., Fuad, I.
    Medicine & Health, 2015;10(1):23-31.
    MyJurnal
    Radiation retinopathy (RR) is a known complication after radiotherapy for Nasopharyngeal Carcinoma (NPC). This study aims to relate the relationship of RR and radiation dose in patients with NPC through assessment with clinical
    funduscopy and fundus fluorescein angiogram (FFA). A cross sectional study was conducted on patients with NPC who had completed radiotherapy treatment in the Oncology Clinic, Universiti Kebangsaan Malaysia Medical Centre (UKMMC). Eighty two eyes of 42 patients were examined and the prevalence of RR was found to be 35.4%. The severity of RR is strongly associated with the dose of radiation to the retina (Spearman correlation value=0.48; p<0.001). The common features of RR assessed by FFA were telangiectatic vessels (26.2%) and capillary non-perfusion (14.3%). Retinal neovasularization occurred in 10.7% of eyes. The level of visual deterioration correlated with the severity of RR with 26% of eyes experiencing a visual acuity of 6/18 or worse. More than one third of patients developed RR, with radiation maculopathy being the commonest cause for significant visual loss. FFA is a useful tool in detecting early signs of radiation retinopathy and maculopathy.
    Keywords: nasopharyngeal carcinoma, fluorescein fundus angiography, retinopathy, radiotherapy
    Study site: Oncology Clinic, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
    Matched MeSH terms: Retina; Retinal Neovascularization
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