Displaying publications 1 - 20 of 56 in total

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  1. See WYN, Ismail F, Sheikh Abdul Kadir SH, Subrayan V
    Curr Eye Res, 2021 Dec 29.
    PMID: 34963422 DOI: 10.1080/02713683.2021.2011326
    PURPOSE/ AIM: The main purpose of this work is to study the cellular viability effect of irradiated riboflavin in cultured human tenon fibroblasts.

    MATERIALS AND METHODS: The tenon tissue was harvested from a patient undergoing strabismus surgery. The human tenon fibroblast cell culture and isolation were performed according to the standard laboratory cell culturing protocol. The cells were divided into three groups: control, treatment with irradiated and non-irradiated riboflavin. There were five different concentrations (0.00156%, 0.003125%, 0.00625%, 0.0125%, 0.025%) in each group of riboflavin. The fibroblasts were treated with riboflavin and the cellular viability was assessed at 24-hour and 48-hour post treatment with MTT 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide colorimetric assay. The absorbance values were analysed using Magellan microplate reader data analysis. A triplicate of readings was taken. The data were presented as mean ± standard deviation of the triplicates. Statistical analysis was performed with Statistical Package for Social Sciences (SPSS) analysis version 23.

    RESULTS: Irradiated riboflavin caused a concentration-dependent cell death in human tenon fibroblast cell culture (p

  2. Lee HN, Subrayan V
    Med J Malaysia, 2021 Nov;76(6):950-952.
    PMID: 34806694
    Internuclear Ophthalmoplegia (INO) is an inability of the ipsilateral adduction with a contralateral horizontal abducting saccade on attempted gaze to the contra-lesion side. Injury to the medial longitudinal fasciculus (MLF) will obstruct the signalling pathway between the ipsilateral abducens nucleus and the contralateral medial rectus muscle. Infarction accounts for 38% of INO cases with mostly being unilateral (87%), followed by demyelination (34%), which mostly being bilateral (73%). Lacunar infarct is the most common ischemic stroke. INO can be easily missed due to its subtle presentation with no complaints from the patients. A full cranial nerves assessment, includes the extraocular muscles movement, is important. Ischemic and demyelinating INO typically recover. We present here of a case of INO following right lacunar infarct in a 72-year-old Malay woman. She had hypertensive crisis due to missed medications. Her blood pressure was well controlled throughout the hospital admission and finally she was discharged home with continuation of care at her primary facility.
  3. Daphne Teh AL, Jayapalan JJ, Loke MF, Wan Abdul Kadir AJ, Subrayan V
    Exp Eye Res, 2021 10;211:108734.
    PMID: 34428458 DOI: 10.1016/j.exer.2021.108734
    This study aimed to investigate the metabolite differences between patients with keratoconus and control subjects and identify potential serum biomarkers for keratoconus using a non-targeted metabolomics approach. Venous blood samples were obtained from patients with keratoconus (n = 20) as well as from age-, gender- and race-matched control subjects (n = 20). Metabolites extracted from serum were separated and analyzed by liquid chromatography/quadrupole time-of-flight mass spectrometer. Processing of raw data and analysis of the data files was performed using Agilent Mass Hunter Qualitative software. The identified metabolites were subjected to a principal component and hierarchical cluster analysis. Appropriate statistical tests were used to analyze the metabolomic profiling data. Together, the analysis revealed that the dehydroepiandrosterone sulfate from the steroidal hormone synthesis pathway was significantly upregulated in patients with keratoconus (p 
  4. Santiagu F, Bakhtiari A, Iqbal T, Khaliddin N, Lansingh VC, Subrayan V
    Int Ophthalmol, 2018 Oct;38(5):2069-2076.
    PMID: 28879527 DOI: 10.1007/s10792-017-0701-5
    BACKGROUND: Purpose of this study is to evaluate changes in the central corneal thickness (CCT) in patients during the third trimester and postpartum phases of normal pregnancy, pregestational diabetes mellitus (DM), and gestational diabetes mellitus (GDM).
    METHODS: This was a prospective study. Patients that fulfilled the inclusion criteria were recruited from the obstetric clinic. They were grouped into normal pregnancy, pregestational DM, and GDM. Ophthalmic assessment and haematological investigations were done during the third trimester (after 28 weeks of gestation) and in the postpartum phase (6 weeks postpartum).
    RESULTS: A total of 192 pregnant patients were recruited for this study. Out of the 192 patients, only 143 of them came back for their follow-up 6 weeks postpartum. A total of 70 (36.5%) normal pregnancy patients, 51 (26.6%) DM patients, and 71 (36.9%) GDM patients were included in this prospective study. Our study showed that the CCT decreased postpartum in all three groups. Patients in all three groups did not have significantly different CCT during the third trimester of pregnancy and postpartum phase. However, patients who had thicker CCT irrespective of the grouping during the third trimester also had a thicker CCT post-delivery (p value <0.001). However, these changes did not appear to affect refractive error and visual acuity.
    CONCLUSIONS: Diabetes mellitus during pregnancy did not appear to influence the CCT.
    Study site: Obstetrics clinic, University Malaya Medical Center (UMMC), Kuala Lumpur, Malaysia
  5. Lim IL, Loo AVP, Subrayan V, Khang TF, See MH, Alip A, et al.
    Breast, 2018 Jun;39:117-122.
    PMID: 29660599 DOI: 10.1016/j.breast.2018.04.003
    It is now increasingly common for breast cancer patients to receive adjuvant tamoxifen therapy for a period of up to 10 years. As survival rate increases, managing tamoxifen ocular toxicities is important for patients' quality of life. Macular pigments in photoreceptor cells protect against free radical damage, which can cause macular degeneration. By reducing macular pigment concentration, tamoxifen may increase the risk of macular degeneration. Here, we compared macular pigment optical density (MPOD) and central macular thickness between breast cancer patients on tamoxifen adjuvant therapy (n = 70), and a control group (n = 72). Multiple regression analysis indicated that MPOD decreases with increasing tamoxifen dosage, up to a threshold of about 20 g, after which MPOD plateaus out. Mean MPOD in the treatment group (mean = 0.40) was significantly lower (p-value = 0.02) compared to the control group (mean = 0.47) for the left eye, and for the right eye (treatment mean = 0.39; control mean = 0.48; p-value = 0.009). No significant difference in mean central macular thickness was found between the treatment and the control group (p-values > 0.4). In the control group, MPOD and central macular thickness showed significant correlation (r∼0.30; p-values 
  6. Lee KR, Peng LY, Iqbal TB, Subrayan V
    Ocul Immunol Inflamm, 2018;26(8):1146-1149.
    PMID: 28362518 DOI: 10.1080/09273948.2017.1298821
    PURPOSE: To report a case of systemic lupus erythematosus-induced choroidal vasculitis.

    METHODS: A 34-year-old woman with a long-standing history of systemic lupus erythematosus had a sudden painless loss of vision in the right eye over 12 hours. Ocular examination revealed a visual acuity of counting fingers of 1 foot on the right eye and 20/20 on the left. There was a relative afferent pupillary defect on the right side with a pink, distinct optic disk margin.

    RESULTS: Optical coherence tomography of the macula and fundus fluorescein angiogram for the eyes were normal. The MRI brain and orbit with the cerebral MRA did not show signs of optic neuritis or occipital vasculitic changes. However, the indocyanine green angiography revealed patches of ill-defined areas of choroidal hypofluorescence in the early- to mid-phase in the macula region.

    CONCLUSION: ICGA becomes the crucial tool in unmasking the presence of choroidal vasculitis.
  7. Bakri NM, Ramachandran V, Kee HF, Subrayan V, Isa H, Ngah NF, et al.
    Kaohsiung J. Med. Sci., 2017 Dec;33(12):602-608.
    PMID: 29132549 DOI: 10.1016/j.kjms.2017.08.003
    Age-related macular degeneration (AMD) is the most widely recognised cause of irreversible vision loss and previous studies have suggested that the advancement of wet AMD is influenced by both modifiable and non-modifiable elements. Single nucleotide polymorphism (SNPs) and copy number of variations (CNVs) have been associated with AMD in various populations, however the results are conflicting. Our aim is to determine the CNVs of Complement Factor H-Related genes among Malaysian subjects with wet AMD. 130 patients with wet AMD and 120 healthy controls were included in this research. DNA was extracted from all subjects and CNVs of CFH, CFHR1 and CFHR3 genes; determined using quantitative real-time PCR and were compared between the two groups. A consistent association was observed between CFH gene and wet AMD susceptibility (P 
  8. Koay CL, Quo MJ, Subrayan V
    Int Ophthalmol, 2017 Jun;37(3):655-671.
    PMID: 27558260 DOI: 10.1007/s10792-016-0306-4
    The purpose of this study was to investigate the reproducibility of choroidal thickness measurements in normal subjects on 3 spectral domain optical coherence tomography instruments, namely: Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA), Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany), and Optovue RTVue (Optovue Inc., Fremont, CA). This cross-sectional non-interventional study was performed in a single institution. Images were obtained in 47 eyes of 47 healthy volunteers which age ranged between 23 and 72 without ocular pathology. All subjects were imaged on the fovea using Cirrus HD 1-line raster, Spectralis enhanced depth imaging, and RTVue retina-cross. The choroid was measured subfoveally and at intervals of 500 µm from the fovea nasally and temporally up to 2500 µm. Paired t test, modified Bland-Altman plot, and Pearson's correlation were used to compare the results. There is no significant difference between the systems for any measurement within 2500 µm either side of the fovea for most points. Inter-observer correlation was strong for RTVue, and moderate in both Cirrus and Spectralis.
  9. Ng JB, Poh RY, Lee KR, Subrayan V, Deva JP, Lau AY, et al.
    Clin. Lab., 2016 Sep 01;62(9):1731-1737.
    PMID: 28164597 DOI: 10.7754/Clin.Lab.2016.160144
    BACKGROUND: Keratoconus is an ocular degeneration characterized by the thinning of corneal stroma that may lead to varying degrees of myopia and visual impairment. Genetic factors have been reported in the pathology of keratoconus where Asians have a higher incidence, earlier onset, and undergo earlier corneal grafts compared to Caucasians. The visual system homeobox 1 (VSX1) gene forms part of a paired-like homeodomain transcription factor which is responsible for ocular development. The gene was marked as a candidate in genetic studies of keratoconus in various populations. Single nucleotide polymorphisms (SNPs) in the VSX1 gene have been reported to be associated with keratoconus. The detection of the SNPs involves DNA amplification of the VSX1 gene followed by genomic sequencing. Thus, the objective of this study aims to establish sensitive and accurate screening protocols for the molecular characterization of VSX1 polymorphisms.

    METHODS: Keratoconic (n = 74) and control subjects (n = 96) were recruited based on clinical diagnostic tests and selection criteria. DNA extracted from the blood samples was used to genotype VSX1 polymorphisms. In-house designed primers and optimization of PCR conditions were carried out to amplify exons 1 and 3 of the VSX1 gene. PCR conditions including percentage GC content, melting temperatures, and differences in melting temperatures of primers were evaluated to produce sensitive and specific DNA amplifications.

    RESULTS: Genotyping was successfully carried out in 4 exons of the VSX1 gene. Primer annealing temperatures were observed to be crucial in enhancing PCR sensitivity and specificity. Annealing temperatures were carefully evaluated to produce increased specificity, yet not allowing sensitivity to be compromised. In addition, exon 1 of the VSX1 gene was amplified using 2 different sets of primers to produce 2 smaller amplified products with absence of non-specific bands. DNA amplification of exons 1 and 3 consistently showed single band products which were successfully sequenced to yield reproducible data.

    CONCLUSIONS: The use of in-house designed primers and optimized PCR conditions allowed sensitive and specific DNA amplifications that produced distinct single bands. The in-house designed primers and DNA amplification protocols established in this study provide an addition to the current repertoire of primers for accurate molecular characterization of VSX1 gene polymorphisms in keratoconus research.

  10. See WYN, Sumugam K, Subrayan V
    Allergy Rhinol (Providence), 2016 Jan 01;7(4):223-226.
    PMID: 28683249 DOI: 10.2500/ar.2016.7.0178
    BACKGROUND: To report an unusual case of compressive optic neuropathy secondary to a large onodi air cell.
    METHOD: Case report.
    RESULTS: A 50 year-old gentlemen presented to the eye clinic with left eye painless loss of vision for one day. Visual acuity was counting finger in the left eye with a positive relative afferent pupillary defect (RAPD). Dilated left fundus examination revealed a pale optic disc. A computed tomography of orbit and brain showed a large left sphenoid sinus with onodi-cell-like projection on the left superior margin of left optic canal impinging on the left optic nerve. He was referred to the otorhinolaryngology team and subsequently underwent left optic nerve decompression. Post-operatively, his left visual acuity improved to 6/60 with reversal of RAPD.
    CONCLUSION: There are many causes of optic neuropathy and compressive optic neuropathy due to large onodi air cell is uncommon. Acute unilateral loss of vision heralds from a multitude of sinister causes and junior residents should be vigilant that onodi air cell pneumotisation could be one of them.
  11. Chee CS, Chang KM, Loke MF, Angela Loo VP, Subrayan V
    PeerJ, 2016;4:e2022.
    PMID: 27280065 DOI: 10.7717/peerj.2022
    AIM/HYPOTHESIS: The aim of our study was to characterize the human salivary proteome and determine the changes in protein expression in two different stages of diabetic retinopathy with type-2 diabetes mellitus: (1) with non-proliferative diabetic retinopathy (NPDR) and (2) with proliferative diabetic retinopathy (PDR). Type-2 diabetes mellitus without diabetic retinopathy (XDR) was designated as control.
    METHOD: In this study, 45 saliva samples were collected (15 samples from XDR control group, 15 samples from NPDR disease group and 15 samples from PDR disease group). Salivary proteins were extracted, reduced, alkylated, trypsin digested and labeled with an isobaric tag for relative and absolute quantitation (iTRAQ) before being analyzed by an Orbitrap fusion tribrid mass spectrometer. Protein annotation, fold change calculation and statistical analysis were interrogated by Proteome Discoverer. Biological pathway analysis was performed by Ingenuity Pathway Analysis. Data are available via ProteomeXchange with identifiers PXD003723-PX003725.
    RESULTS: A total of 315 proteins were identified from the salivary proteome and 119 proteins were found to be differentially expressed. The differentially expressed proteins from the NPDR disease group and the PDR disease group were assigned to respective canonical pathways indicating increased Liver X receptor/Retinoid X receptor (LXR/RXR) activation, Farnesoid X receptor/Retinoid X receptor (FXR/RXR) activation, acute phase response signaling, sucrose degradation V and regulation of actin-based motility by Rho in the PDR disease group compared to the NPDR disease group.
    CONCLUSIONS/INTERPRETATION: Progression from non-proliferative to proliferative retinopathy in type-2 diabetic patients is a complex multi-mechanism and systemic process. Furthermore, saliva was shown to be a feasible alternative sample source for diabetic retinopathy biomarkers.
  12. Peyman M, Tai LY, Khaw KW, Ng CM, Win MM, Subrayan V
    Int Ophthalmol, 2015 Oct;35(5):651-5.
    PMID: 25189684 DOI: 10.1007/s10792-014-9989-6
    To assess the intra-observer repeatability and inter-observer reproducibility of central corneal thickness (CCT) measurements of PachPen (Accutome, Inc., Pennsylvania, USA), a hand-held, portable ultrasonic pachymeter when used by an ophthalmic nurse compared to an ophthalmologist. Ophthalmology Clinic, University of Malaya Medical Center In this prospective study, CCT was measured in 184 eyes of 92 healthy subjects, first by a corneal surgeon experienced in ultrasound pachymetry (Observer 1) followed by an ophthalmic nurse new to the procedure (Observer 2). Nine measurements were obtained from each eye by each observer, independently. Measurements were compared between the observers. Coefficients of repeatability and reproducibility were calculated. The Bland-Altman plot was used to assess agreement between observers. Mean age of the study population was 54.3 ± 15.2 years old and consisted of 43.5% male. Mean CCT as measured by Observers 1 and 2 were 528.3 ± 32.9 and 530.7 ± 33.3 µm, respectively. Observer 1 showed higher repeatability of measurements compared to that of Observer 2 (coefficient of repeatability 3.46 vs. 5.55%). The measurements by both observers showed high correlation (0.96) and good agreement (mean difference -2.4 µm; 95% limits of agreement -21.4, 16.7 µm). Coefficient of reproducibility of measurements between observers was 5.08%. Accutome PachPen hand-held ultrasound pachymeters gives excellent intra-observer repeatability and inter-observer reproducibility by personnel of different training grades.
  13. Naicker P, Sundralingam S, Peyman M, Juana A, Mohamad NF, Win MM, et al.
    Int Ophthalmol, 2015 Aug;35(4):459-66.
    PMID: 25024102 DOI: 10.1007/s10792-014-9970-4
    To determine the accuracy of intraocular lens (IOL) calculations in eyes undergoing phacoemulsification cataract surgery with IOL implantation using immersion A-scan ultrasound (US) and Lenstar LS 900(®) biometry. In this prospective study, 200 eyes of 200 patients were randomized to undergo either Lenstar LS 900(®) or immersion A-scan US biometry to determine the IOL dioptric power prior to phacoemulsification cataract surgery. Post-operative refractive outcomes of these two groups of patients were compared. The result showed no significant difference between the target spherical equivalent (SE) and the post-operative SE value by the Lenstar LS 900(®) (p value = 0.632) or immersion A-scan US biometry (p value = 0.438) devices. The magnitude of difference between the two biometric devices were not significantly different (p value = 0.868). There was no significant difference in the predicted post-operative refractive outcome between immersion A-scan US biometry and Lenstar LS 900(®). Based on the results, the immersion A-scan US technique is as accurate as Lenstar LS 900(®) in the hands of an experienced operator.
  14. Bin NJ, Heng HM, Poh R, Noor SM, Subrayan V
    Retina, 2015 Jun;35(6):1266-72.
    PMID: 25549071 DOI: 10.1097/IAE.0000000000000446
    To evaluate the association of phospholipase A2, Group V (PLA2G5), with benign familial fleck retina in a consanguineous family with triplets.
  15. Ismail F, Peyman M, Waran V, Vasudevan S, Subrayan V
    Optom Vis Sci, 2015 Apr;92(4 Suppl 1):S33-5.
    PMID: 25730333 DOI: 10.1097/OPX.0000000000000528
    To report a rare case of nasal chondroma presenting as hypertelorism.
  16. Koay CL, Patel DK, Tajunisah I, Subrayan V, Lansingh VC
    Int Ophthalmol, 2015 Apr;35(2):201-7.
    PMID: 24652461 DOI: 10.1007/s10792-014-9932-x
    To determine the avoidable causes of childhood blindness in Malaysia and to compare this to other middle income countries, low income countries and high income countries. Data were obtained from a school of the blind study by Patel et al. and analysed for avoidable causes of childhood blindness. Six other studies with previously published data on childhood blindness in Bangladesh, Ethiopia, Nigeria, Indonesia, China and the United Kingdom were reviewed for avoidable causes. Comparisons of data and limitations of the studies are described. Prevalence of avoidable causes of childhood blindness in Malaysia is 50.5 % of all the cases of childhood blindness, whilst in the poor income countries such as Bangladesh, Ethiopia, Nigeria and Indonesia, the prevalence was in excess of 60 %. China had a low prevalence, but this is largely due to the fact that most schools were urban, and thus did not represent the situation of the country. High income countries had the lowest prevalence of avoidable childhood blindness. In middle income countries, such as Malaysia, cataract and retinopathy of prematurity are the main causes of avoidable childhood blindness. Low income countries continue to struggle with infections such as measles and nutritional deficiencies, such as vitamin A, both of which are the main contributors to childhood blindness. In high income countries, such as the United Kingdom, these problems are almost non-existent.
  17. Chang KM, Patel DK, Tajunisah I, Subrayan V
    Asia Pac J Public Health, 2015 Mar;27(2):217-24.
    PMID: 22887807 DOI: 10.1177/1010539512455047
    Retinopathy of prematurity (ROP) is one of the most important causes of childhood blindness worldwide. The trend of ROP in Malaysia was unclear because there was no national registry before 2002. The purpose of this study is to analyze ROP students of different ages in the schools for the blind in Malaysia in order to evaluate the trend of ROP from 1992 to 2001. Data were obtained from a previous survey of 24 blind schools. It was found that 78 students or 17.4% were blind/severely visual impaired as a result of ROP. There was a significant surge in the number of ROP students who were born in 1994 when the use of synthetic surfactants was first introduced in Malaysia; otherwise there was no increasing trend in the number of students with ROP. However, the percentage of ROP in total was increasing, which indicates that ROP is becoming a more important cause of childhood blindness in this country.
  18. Noh SM, Abdul Kadir SH, Crowston JG, Subrayan V, Vasudevan S
    Mol Vis, 2015;21:1191-200.
    PMID: 26539031
    Inhibiting exaggerated wound healing responses, which are primarily mediated by human Tenon's fibroblast (HTF) migration and proliferation, has become the major determining factor for a successful trabeculectomy. Antivascular endothelial growth factor (anti-VEGF) has showed promising results as a potential antifibrotic candidate for use concurrently in trabeculectomy. Preliminary cohort studies have revealed improved bleb morphology following trabeculectomy augmented with ranibizumab. However, the effects on HTFs remain unclear. This study was conducted to understand the effects of ranibizumab on transforming growth factor (TGF)-β1 and transforming growth factor (TGF)-β2 expression by HTFs.
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