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Prof. Henry Chan
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Prof. Henry CHAN Ho-lung

Professor

Prof. Henry CHAN Ho-lung (陳浩龍) currently is a Professor in the School of Optometry, The Hong Kong Polytechnic University. He is also an Honorary Associate Professor in the Department of Ophthalmology, The University of Hong Kong.

  • HJ504
  • +852 2766 7937
  • henryhl.chan@polyu.edu.hk
  • Prof. Chan's main research area is visual electroretinogram (ERG). He specializes in techniques and experimental planning/setting for the study of visual electrophysiology.

Biography

Prof. Henry Ho-lung CHAN (陳浩龍) completed his undergraduate training in Optometry in The Hong Kong Polytechnic and obtained his PhD in The Hong Kong Polytechnic University in the area of clinical electrophysiology in vision. His current position is Professor in the School of Optometry, The Hong Kong Polytechnic University. He also obtained his fellowship of American Academy of Optometry (FAAO). He is currently the Honorary Associate Professor in the Department of Ophthalmology, The University of Hong Kong. 

Research Overview

In 2006, he developed a new paradigm – modified global flash multifocal electroretinogram (mfERG) –for early glaucoma diagnosis. This new method has over 90% of sensitivity and specificity for differentiating eyes with glaucoma from normal eyes. This special measurement has been proved to detect the glaucomatous changes at least 4 years before detected by the current clinical tests.

Over the same period, he used the mfERG to investigate the myopia eye. The central inner retinal activities obtained using a specific multifocal ERG measurement is significantly correlated with later myopia progression in children. It is a potential reference for juvenile myopia development.

Recently, he also worked on the area of the environmental influence in myopia progression. It is a new area to explore the mechanism of myopia development. Moreover, he also focuses on the treatment of eye diseases using Lycium Barbarum (LB) which is a commonly used TCM. One of his studies showed that a 12-month LB treatment was able to preserve vision and retinal structure in Retinitis Pigmentosa (RP) patients.

Education and Academic Qualifications

  • Associate Professor, School of Optometry, PolyU (2005 – present)
  • Assistant Professor, Department of Optometry and Radiography, PolyU (1999-2005)
  • Demonstrator, Department of Optometry and Radiography, PolyU (1997-1999)
  • Honorary Associate Professor, Department of Ophthalmology, Li Ka Shing Faculty of Medicine, Hong Kong University (2007 – present)
  • Honorary Research Fellow, School of Life & Health Sciences, Aston University, UK (2016 – 2018)
  • Honorary Associate Professor, School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, Hong Kong University (20152016)
  • Honorary Associate Professor, Department of Anatomy, Li Ka Shing Faculty of Medicine, Hong Kong University (20052015)
  • Honorary Assistant Professor, Department of Anatomy, Li Ka Shing Faculty of Medicine, Hong Kong University (2003 2005)
  • Visiting Optometrist, Department of Ophthalmology, Queen Mary Hospital (2007 – 2009)
  • Adjunct Clinical Associate Professor of Optometry, School of Optometry, Indiana University, US (2007 – 2009)
  • Member of Education Committee for the Optometrists Board in Hong Kong (Nov 2008 – Oct 2014)
  • Director of The Hong Kong Federation of Societies for Prevention of Blindness (Jan 2013 – Dec 2014; Jan 2017 – present)
  • Vice-president of The Hong Kong Society of Professional Optometrists (Chairman of the Professional Development Committee) (2003 – 2004)
  • Registered Optometrist (Part I) in Hong Kong (1996 – present)
  • Credentialed Optometrist and overseas examiner, Civil Aviation Authority (CAA) of New Zealand (2006-2008)
  • Member of Hong Kong Society of Professional Optometrists (1991 – present)
  • Member of The International Society of Clinical Electrophysiology for Vision (ISCEV) (2000 – present)

Professional Qualifications

  • Fellow of the American Academy of Optometry

Research Interests

  • Visual electrophysiology (both in human and animal studies, basic and clinical research)
  • Visual Neuroscience and psychophysics (basic and clinical research)
  • Glaucoma research
  • Retinal physiology and diseases
  • Myopia research
  • Retinitis pigmentosa research
  • Diabetic retinopathy research
  • Age-related maculopathy research

Research Output

In this exploratory analysis of 2 cohort studies, the intervention using defocus incorporated multiple segments (DIMS) lens was significantly associated with slower myopia progression and axial elongation during COVID-19 lockdown by 46% and 34%, respectively, when compared with regular single vision lens. Optical defocus intervention was significantly associated with slower myopia progression in schoolchildren, which was exaggerated during the COVID-19 lockdown.
This study demonstrated that the characteristics of near work scene profile (e.g. defocus dispersion, etc.) and home size strongly influence further myopia progression. In addition, from my unpublished data, myopia progression in an animal model was found to be dependent on the composition of spatial stimuli. All these findings could allow the future development of a new measure to provide appropriate spatial details in the environment
Glaucoma is an irreversible blinding disease that causes compartmentalized degeneration of the retinal ganglion cells. As glaucoma is a multifactorial disease, current standard treatments depend largely on altering a single risk factor, elevated intraocular pressure (IOP). Lowering the IOP, remains the mainstay of current standard clinical protocol. However, a proportion of glaucoma sufferers continued to deteriorate despite well-controlled IOP. To target this problem, complementary and alternative medicines, e.g. Traditional Chinese Medicine (TCM), are widely considered to be applied on top of the current standard IOP lowering treatments. Pretreatment with LBP, as a kind of TCM with a strong neuroprotective effect, had been reported to protect against retinal damage in animal glaucoma models. However, there was no published evidence of post-treatment effect of LBP in glaucoma. This study successfully demonstrated the therapeutical effect of LBP under post-treatment condition to delay both functional and structural deterioration in both acute and chronic glaucoma animal models. The results will help in developing the next generation of glaucoma drugs in the future.
This study aimed to evaluate the drug treatment effect of atropine in myopia control on the children with different predicted rates of myopia progression. The results showed that atropine gives very different effects on children with different predicted myopia progression rates. It is a very important finding which will help to decide the customized clinical treatment protocol for an individual child.
Abnormal neural rewiring in the mutated retinitis pigmentosa (RP) retina is solid evidence of the neural network re-construction. My research findings found an unbalanced activities of ON- and OFF-pathways which were likely to cause abnormal feedback from the inner retina and finally modify and trigger an overall weak electro-retinal response from the mutated retina This new evidence introduced a new concept of retinal neuroplasticity and provides an alternative direction for treatment. This study was to investigate the effectiveness of Lycium Barbarum supplement to delay retinal degeneration in RP patients. Lycium Barbarum was found to have strong neuroprotective effects which can reduce the oxidative stress in the retina and could help delay or minimize degeneration of retinal cells in RP. A local TCM company has started to produce this supplement for the market.
Myopia (short-sightedness) is caused by visual-guided ocular growth. The retinal electrophysiology in a myopic child differs from that of a myopic adult. It is likely related to the myopic progression. In this study.the central inner retinal activities obtained by the specific multifocal ERG paradigm was significantly correlated with later myopia progression. This suggested that subclinical reduction of the central inner retinal function in young children could be a myopigenic factor and it might be a potential reference marker for juvenile myopia development.
This study first showed that the human retina can respond to different signs of defocus with various magnitudes in terms of electrophysiology. It is a novel finding in humans, since only animal results had been previously reported. I also determined that the human retina had different responses to various spatial stimulations under different levels of optical defocus. Visual stimuli are composed of various spatial details. If detection of defocus is spatially tuned, a particular range of spatial frequencies may act as regulators for eyeball growth in response to defocus. Hence, manipulating the spatial details in the environment may be another important factor in retarding myopia progression.
This study aimed to develop a new method by application of the concept of temporal visual function, rather than spatial visual function, bypassing the detriment of ocular media (e.g. Cataract) to measure retinal activities. This was a novel approach in clinical examination, and it will benefit the fields of both optometry and ophthalmology.
This study was to apply multifocal ERG to investigate glaucomatous lesions in the human retina. A new visual electrophysiological examination method was developed to overcome the traditional problems to improve the diagnostic effectiveness for glaucoma detection. The sensitivity and the specificity of this new technique are both more than 90%. Further study showed that this technique can detect the early manifestations of glaucomatous damage at least 4 years earlier than all the current clinical glaucoma assessments.
  1. Chan HHL, Lam HI, Choi KY, Li SZ, Lakshmanan Y, Yu WY, Chang RCC, Lai J, So KF. Delay of cone degeneration in retinitis pigmentosa using a 12-month treatment with Lycium barbarum supplement. J Ethnopharmacol 2019;236:336-344
  2. Lakshmanan Y, Wong FSY, Yu WY, Li SZC, Choi KY, So KF, Chan HHL. Lycium Barbarum Polysaccharides rescue neurodegeneration in an acute ocular hypertension rat model under pre- and post-treatment Conditions. Invest Ophthalmol Vis Sci 2019;60:2023-2033.
  3. Lam C, Li KK, Do CH, Chan H, To CH, Kwong JMK. Quantitative profiling of regional protein expression in rat retina after partial optic nerve transection using fluorescence difference two-dimensional gel electrophoresis. Mol Med Rep 2019;20:2734-2742.
  4. Tse JSH, Lam TC, So KHY, Lam CDM, Cheung JKW, Sze AYH, Wong GTK, Wong ACK, Yee GMC, Chan HHL. Data on Assessment of safety and tear proteome change in response to orthokeratology lens – insight from integrating clinical data and next generation proteomics. Data in brief 2020;29:105186.
  5. Choi KY, Mok AYT, Do CW, Lee PH, Chan HHL. The diversified defocus profile of the near-work environment and myopia development. Ophthal Physiol Opt 2020;40:463-471.
  6. Lakshmanan Y, Wong FSY, Zuo B, Bui BV, Chan HHL. Longitudinal outcomes of circumlimbal suture model induced chronic ocular hypertension in Sprague-Dawley albino rats. Graefe’s Arch Clin Exp Ophthalmol 2020;258:2715-2728.
  7. Abokyi S, Shan SW, To CH, Chan HHL, Tse DYY. Autophagy upregulation by the TFEB inducer Trehalose protects against oxidative damage and cell death associated with NRF2 inhibition in human RPE cells. Oxid Med Cell Longev 2020 Jul; doi.org/10.1155/2020/5296341
  8. Fung MMY, Choi KY, Chan HHL. The effect of simultaneous dual-focus integration on the global flash multifocal electroretinogram in the human eye. Ophthal Physiol Opt 2020;41:171-178.
  9. Yu WY, Cheong AMY, Chan HHL, Lee MH, Woo G. Importance of Longitudinal Visual Function Assessments after Orbital Cavernoma Removal. Optometry and Visual Performance 2021;9:80-85.
  10. Wong NK, Lai D, Chan HHL, Lam BYH. Neural and Retinal Characteristics in Relation to Working Memory in Older Adults with Mild Cognitive Impairment. Curr Alzheimer Res 2021;18:185-195.
  11. Choi KY, Wong HY, Chan HHL. Utilizing Advanced Technology to Facilitate Diagnosis of Rare Retinal Disorders - A Case of Bietti Crystalline Dystrophy. Optom Vis Sci 2021 doi: 10.1097/OPX.0000000000001763
  12. Abokyi S, Shan SW, Lam CHI, Catral KP, Pan F, Chan HHL, To CH, Tse DYY. Targeting lysosomes to reverse hydroquinone-induced autophagy defects and oxidative damage in human retinal pigment epithelial cells. Int J Mol Sci 2021;22:9042 doi.org/10.3390/imjs22169042
  13. Tse JSH, Cheung JKW, Wong GTK, Lam TC, Choi KY, So KHY, Lam CDM, Sze AYH, Wong ACK, Yee GMC, Chan HHL. Integrating clinical data and tear proteomics to assess efficacy, ocular surface status, and biomarker response after orthokeratology lens wear. Transl Vis Sci Technol 2021;10:18 https://doi.org/10.1167/tvst.10.11.18
  14. Choi KY, Chan SSH, Chan HHL. Effect of spatially-related environmental risk factors in visual scenes on myopia. Clin Exp Optom 2021 DOI: 10.1080/08164622.2021.1983400

Esteem Measures

Honorary Associate Professor, Department of Ophthalmology, Li Ka Shing Faculty of Medicine, Hong Kong University (2007 – present)

Editorial board member of Graefes Archive for Clinical and Experimental Ophthalmology (2011-present)

Fellow of The American Academy of Optometry (AAO) (2002 – present)

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