Pick Topic
Review Topic
List Experts
Examine Expert
Save Expert
  Site Guide ··   
Glaucoma: HELP
Articles by Louis Tong
Based on 6 articles published since 2008

Between 2008 and 2019, L. Tong wrote the following 6 articles about Glaucoma.
+ Citations + Abstracts
1 Review Computer-aided diagnosis of glaucoma using fundus images: A review. 2018

Hagiwara, Yuki / Koh, Joel En Wei / Tan, Jen Hong / Bhandary, Sulatha V / Laude, Augustinus / Ciaccio, Edward J / Tong, Louis / Acharya, U Rajendra. ·Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489, Singapore. · National University of Singapore, Institute of System Science. · Department of Ophthalmology, Kasturba Medical College, Manipal, India. · National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore. · Department of Medicine, Columbia University, New York, USA. · Ocular Surface Research Group, Singapore Eye Research Institute, Singapore; Cornea and External Eye Disease Service, Singapore National Eye Center, Singapore; Eye Academic Clinical Program, Duke-NUS Medical School, Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. · Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489, Singapore; Department of Biomedical Engineering, School of Science and Technology, Singapore School of Social Sciences, Singapore; School of Medicine, Faculty of Health and Medical Sciences, Taylor's University, Subang Jaya, Malaysia. Electronic address: aru@np.edu.sg. ·Comput Methods Programs Biomed · Pubmed #30337064.

ABSTRACT: BACKGROUND AND OBJECTIVES: Glaucoma is an eye condition which leads to permanent blindness when the disease progresses to an advanced stage. It occurs due to inappropriate intraocular pressure within the eye, resulting in damage to the optic nerve. Glaucoma does not exhibit any symptoms in its nascent stage and thus, it is important to diagnose early to prevent blindness. Fundus photography is widely used by ophthalmologists to assist in diagnosis of glaucoma and is cost-effective. METHODS: The morphological features of the disc that is characteristic of glaucoma are clearly seen in the fundus images. However, manual inspection of the acquired fundus images may be prone to inter-observer variation. Therefore, a computer-aided detection (CAD) system is proposed to make an accurate, reliable and fast diagnosis of glaucoma based on the optic nerve features of fundus imaging. In this paper, we reviewed existing techniques to automatically diagnose glaucoma. RESULTS: The use of CAD is very effective in the diagnosis of glaucoma and can assist the clinicians to alleviate their workload significantly. We have also discussed the advantages of employing state-of-art techniques, including deep learning (DL), when developing the automated system. The DL methods are effective in glaucoma diagnosis. CONCLUSIONS: Novel DL algorithms with big data availability are required to develop a reliable CAD system. Such techniques can be employed to diagnose other eye diseases accurately.

2 Article Diagnosis of retinal health in digital fundus images using continuous wavelet transform (CWT) and entropies. 2017

Koh, Joel E W / Acharya, U Rajendra / Hagiwara, Yuki / Raghavendra, U / Tan, Jen Hong / Sree, S Vinitha / Bhandary, Sulatha V / Rao, A Krishna / Sivaprasad, Sobha / Chua, Kuang Chua / Laude, Augustinus / Tong, Louis. ·Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489 Singapore, Singapore. · Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489 Singapore, Singapore; Department of Biomedical Engineering, School of Science and Technology, SIM University, 599491 Singapore, Singapore; Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Malaysia, Malaysia. Electronic address: aru@np.edu.sg. · Department of Instrumentation and Control Engineering, Manipal Institute of Technology, Manipal University, Manipal 576104, India. · Visiting Scientist, Global Biomedical Technologies, CA, USA. · Department of Ophthalmology, Kasturba Medical College, Manipal 576104, India. · Consultant ophthalmologist, NIHR Moorfields Biomedical Research Centre, London, United Kingdom. · National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore 308433, Singapore. · Singapore Eye Research Institute, Ocular Surface Research Group, Singapore, Singapore; Singapore National Eye Center, Cornea and External Eye Disease Department, Singapore, Singapore; Duke-National University of Singapore Graduate Medical School, Singapore, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. ·Comput Biol Med · Pubmed #28351716.

ABSTRACT: Vision is paramount to humans to lead an active personal and professional life. The prevalence of ocular diseases is rising, and diseases such as glaucoma, Diabetic Retinopathy (DR) and Age-related Macular Degeneration (AMD) are the leading causes of blindness in developed countries. Identifying these diseases in mass screening programmes is time-consuming, labor-intensive and the diagnosis can be subjective. The use of an automated computer aided diagnosis system will reduce the time taken for analysis and will also reduce the inter-observer subjective variabilities in image interpretation. In this work, we propose one such system for the automatic classification of normal from abnormal (DR, AMD, glaucoma) images. We had a total of 404 normal and 1082 abnormal fundus images in our database. As the first step, 2D-Continuous Wavelet Transform (CWT) decomposition on the fundus images of two classes was performed. Subsequently, energy features and various entropies namely Yager, Renyi, Kapoor, Shannon, and Fuzzy were extracted from the decomposed images. Then, adaptive synthetic sampling approach was applied to balance the normal and abnormal datasets. Next, the extracted features were ranked according to the significances using Particle Swarm Optimization (PSO). Thereupon, the ranked and selected features were used to train the random forest classifier using stratified 10-fold cross validation. Overall, the proposed system presented a performance rate of 92.48%, and a sensitivity and specificity of 89.37% and 95.58% respectively using 15 features. This novel system shows promise in detecting abnormal fundus images, and hence, could be a valuable adjunct eye health screening tool that could be employed in polyclinics, and thereby reduce the workload of specialists at hospitals.

3 Article Effect of chronic anti-glaucoma medications and trabeculectomy on tear osmolarity. 2013

Lee, S-Y / Wong, T T / Chua, J / Boo, C / Soh, Y F / Tong, L. ·Singapore Eye Research Institute, Singapore, Singapore. ·Eye (Lond) · Pubmed #23846375.

ABSTRACT: PURPOSE: To evaluate the tear film osmolarity (TFO) and ocular surface clinical signs and symptoms in chronically medicated glaucoma patients and post-trabeculectomy patients. METHODS: This is a single-center, prospective case-controlled study. One-hundred and thirty eyes of 130 participants aged ≥ 45 years were included (49 normal controls, 50 glaucoma patients on chronic preserved anti-glaucoma medication ≥ 6 months, and 31 post-trabeculectomy patients not on medication ≥ 6 months). TFO, tear break-up time (TBUT), Schirmer's test I and dry eye symptoms were evaluated. Data from both groups of glaucoma patients were compared with age and sex-matched controls. Logistic regression was performed to calculate the odds ratios. RESULTS: Mean TFO in the three groups were 301.4 ± 7.7, 307.0 ± 9.3, and 307.4 ± 11.6 mOsm/l, respectively. Compared with normal controls, chronically medicated glaucoma patients and post-trabeculectomy patients were more likely to have a raised TFO, with odds ratios (95% CI) of 4.43 (1.74-11.32) and 2.76 (1.02-7.94), respectively. Both groups of glaucoma patients were also more likely to experience dry eye symptoms, with ORs of 4.72 (1.92-11.59) and 4.24 (1.54-11.72). There was no significant difference in TFO and symptoms between both groups of glaucoma patients, and in TBUT and Schirmer's test across all three groups. CONCLUSIONS: Patients on chronic topical anti-glaucoma medication and post-trabeculectomy patients were more likely to have raised TFO and dry eye symptoms, suggesting significant ocular surface disease. Glaucoma practitioners should be aware that dry eye symptoms and raised TFO may occur in the absence of TBUT and Schirmer's test abnormality.

4 Article Proteomic profiling of inflammatory signaling molecules in the tears of patients on chronic glaucoma medication. 2011

Wong, Tina T / Zhou, Lei / Li, Jing / Tong, Louis / Zhao, Shao Zhen / Li, Xiao Rong / Yu, Shang Juan / Koh, Siew Kwan / Beuerman, Roger W. ·Singapore Eye Research Institute, Singapore. tina.wong.t.l@snec.com.sg ·Invest Ophthalmol Vis Sci · Pubmed #21697136.

ABSTRACT: PURPOSE: To identify the tear proteins associated with the long-term use of glaucoma medication by using proteomic analysis and to compare these proteins to those previously reported in primary dry eye disease. METHODS: Eighteen patients treated with topical antiglaucoma medications and 10 normal age-matched subjects with no prior topical treatment were recruited for the study. Tears were collected by using Schirmer's strip and analyzed by iTRAQ (isobaric tag for relative and absolute quantitation) for tear proteins by mass spectrometry. Conjunctival samples were collected and RNA expression determined by PCR. RESULTS: Of the 124 identified tear proteins (99% confidence, ProtScore ≥ 2.0), we found that the tear levels of S100-A8, S100-A9, mammaglobin B, and 14-3-3 ζ/δ were significantly increased in the medicated group compared with levels in the nonmedicated group (P < 0.05). For S100-A9, mammaglobin B, and 14-3-3 ζ/δ, use of topical medication for less than 1 year did not reach statistical significance compared with that in the nonmedicated group. Eyes on topical medication for less than 1 year showed a decrease in proline-rich 4 protein tear level (P = 0.0049) compared to nonmedicated group. The tear proteins detected in the medicated group differed from those in the primary dry eye group. CONCLUSIONS: Treatment with topical antiglaucoma medications for longer than 1 year may start to induce ocular surface inflammation. The inflammatory tear protein profile present in chronically medicated glaucomatous eyes appears to be different from that found in primary dry eye. Identification of tear proteins specific to medicated glaucomatous eyes will help to specifically develop targeted screening modalities and therapeutic agents different from current conventional dry eye management.

5 Article The use of HRT with and without the aid of disc photographs. 2011

Loon, Seng Chee / Tong, Louis / Gazzard, Gus / Chan, Yiong Huak / Sim, Ee Ling / Aung, Tin / Tan, Donald T H / Healey, P R / Wong, Tien Yin / Koh, Victor / Saw, Seang Mei. ·Department of Ophthalmology, National University Hospital, Singapore National Eye Centre, London, UK. ploonsc@yahoo.com ·J Glaucoma · Pubmed #20577099.

ABSTRACT: PURPOSE: To evaluate the measurement of optic disc morphology using Heidelberg Retinal Tomography (HRT) with and without the aid of optic disc photos. METHODS: One hundred three children (aged 11 and 12 y, 52 boys) were selected randomly from the Singapore Cohort study of Risk Factors for Myopia. Optic nerve head topography and retinal nerve fiber layer thickness measurements were assessed using the HRT-II (Heidelberg, Germany) scanning laser ophthalmoscope. All contour lines were drawn by the same researcher on 2 occasions. The first drawing was made without optic disc photographs but using the 3-dimensional rotation assessment. The second drawing was made with the additional aid of digital monoscopic optic disc photographs. RESULTS: There was a high correlation between the measurements taken with and without optic disc photographs. For the global disc area, the difference between the mean readings was 0.67 mm and the intraclass correlation (ICC) was 0.81 [95% confidence interval (CI) 0.73-0.86]. The mean difference for the global cup-to-disc ratio was 0.03 [ICC 0.86 (95% CI 0.80-0.90)]. The ICCs were high across almost all of the readings except rim volume, in which the ICC was 0.57 (95% CI 0.43-0.69). CONCLUSIONS: This study shows minimal differences in HRT measured optic disc parameters when optic disc photos are used to aid in the definition of the scleral ring. Omitting the use of disc photographs in measuring HRT outputs may translate into significant savings in time and logistics in simultaneously obtaining HRT and optic disc photographs in large population-based studies.

6 Article Corneal biomechanics, thickness and optic disc morphology in children with optic disc tilt. 2008

Lim, L / Gazzard, G / Chan, Y-H / Fong, A / Kotecha, A / Sim, E-L / Tan, D / Tong, L / Saw, S-M. ·Singapore Eye Research Institute, Singapore. ·Br J Ophthalmol · Pubmed #18703551.

ABSTRACT: AIMS: To determine the associations between corneal biomechanical parameters as measured by the Reichert Ocular Response Analyser (ORA) and disc morphology and retinal nerve fibre layer thickness (RNFL) measured by the Heidelberg Retinal Tomograph (HRT) II in Singaporean children. METHODS: This is a cross-sectional study conducted on a subset of children enrolled in the Singapore Cohort Study of the Risk Factors of Myopia (SCORM). Corneal hysteresis (CH), corneal resistance factor (CRF) and central corneal thickness (CCT) were measured with the ORA. Optic disc morphology and RNFL thickness were assessed by the HRT II. Cycloplegic refraction and ultrasound A-scans were also performed, and disc tilt was assayed from stereo photographs. RESULTS: 102 subjects (mean age 12.01 (SD 0.57) years; range 11-14 years) were included in the study. The mean CH was 12.00 (1.40) mm Hg, the mean CRF was 11.99 (1.65) mm Hg, and the mean CCT was 581.12 (33.53) mum. Eyes with tilted discs had significantly longer axial lengths and more myopic refraction than eyes without tilted discs. There were no significant correlations between CH, CRF or CCT and the HRT II parameters, after the application of the Bonferroni correction. When stratified for disc tilt, however, the global disc area was significantly correlated with CCT (r = -0.49, p = 0.001). CONCLUSION: Corneal biomechanical properties as measured with the ORA do not vary with optic disc parameters or RNFL. Central corneal thickness is correlated with disc area in Singaporean schoolchildren with tilted discs. This relationship may influence glaucoma risk in myopic subjects.