Dennis S C Lam

Sun Yat-Sen University, Shengcheng, Guangdong, China

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Publications (810)2769.2 Total impact

  • Dennis S. C. Lam ·

    08/2015; 4(1). DOI:10.1097/APO.0000000000000116
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    ABSTRACT: To identify clinical factors correlating with failure to control intraocular pressure (IOP) in primary angle-closure glaucoma (PACG) eyes with cataract after phacoemulsification or phacotrabeculectomy. Retrospective analysis of two prospective randomized controlled clinical trials. Primary angle-closure glaucoma eyes with cataract received phacoemulsification or phacotrabeculectomy. Failure was defined as having IOP of 21mm Hg or greater, or requiring glaucoma drugs to maintain an IOP of less than 21 mm Hg, or having had additional IOP-lowering surgery. Factors correlating with failure at 24 months after surgery were identified using logistic regression model. One hundred twenty-three PACG eyes with cataract and receiving phacoemulsification (n = 62) and phacotrabeculectomy (n = 61) were analyzed. With univariate analysis, factors associated with failure included a higher preoperative IOP, a higher preoperative requirement for glaucoma drugs, absence of plateau iris configuration, and phacoemulsification alone. With multivariate analysis, factors associated with failure included a higher preoperative IOP [odds ratio (OR), 1.732 per increase in IOP of 5 mm Hg], a higher preoperative requirement for glaucoma drugs (OR, 1.913), and performance of phacoemulsification alone (OR, 10.24). In PACG eyes with cataract, higher preoperative IOP and increased requirement for glaucoma drugs correlate with failure to control IOP after phacoemulsification or phacotrabeculectomy. Phacotrabeculectomy is more likely than phacoemulsification to achieve IOP control.
    06/2015; 4(1):56-59. DOI:10.1097/APO.0000000000000091
  • Article: Cataract

    06/2015; DOI:10.1038/nrdp.2015.14
  • Vineet Ratra · Dennis S. C. Lam ·
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    ABSTRACT: Small pupils pose problems for cataract surgery. The pupil is dilated with topical mydriatic drugs for all cataract surgeries to improve the surgeon's access to, and visualization of, the lens nucleus, cortex, and capsular structures. Limited dilation poses a risk of surgical complications such as iris trauma or tearing of the anterior or posterior capsule. There are many ways and methods to achieve the appropriate pupil dilation, from pre-operative medications to intraoperative pharmacological and/or surgical methods. A management algorithm for small pupil will be discussed in this review. The various methods and maneuvers may work in isolation or combination to achieve adequate pupil dilation.
    05/2015; 4(3). DOI:10.1097/APO.0000000000000119
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    ABSTRACT: To investigate the changes of retinal oxygen saturation (Sat O2) concentrations, choroidal thickness (CT), and retinal nerve fibre layer (RNFL) in eyes with trabeculectomy-required acute primary angle closure (APAC). Prospective, longitudinal study. Twenty-three eyes with trabeculectomy-required APAC were recruited. Retinal oximetry was performed at postoperative day one and again at approximately 1 month. CT and the RNFL were tested on the same day. A paired t test and Pearson correlation were used for analysis. Mean Sat O2 increased in retinal arterioles from 88.74% ± 14.36% at postoperative day 1 to 96.61% ± 18.42% at 1 month (p = 0.049). The mean diameter of the arterioles was statistically different between postoperative day 1 and 1 month (p = 0.044), as was the mean diameter of the venules (p = 0.027). APAC eyes at postoperative 1 month had a thinner mean CT, compared with day 1 (p = 0.002). No significant difference was found in the RNFL between postoperative day 1 and 1 month (p > 0.05). The Sat O2 in retinal arterioles correlated with the mean diameter of the arterioles at postoperative day 1 (r = -0.482, p = 0.020) and at 1 month (r = -0.463, p = 0.026). No significant correlation was found between retinal Sat O2 and other parameters. Increased Sat O2 in retinal arterioles, changed vessel diameter, and thinner CT from postoperative day 1 to 1 month suggest gradual recovery from APAC. However, the different pathophysiologies for APAC still need further study to prove. Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.
    Canadian Journal of Ophthalmology 04/2015; 50(2):159-165. DOI:10.1016/j.jcjo.2014.11.015 · 1.33 Impact Factor
  • Dennis S C Lam ·

    03/2015; 4(2). DOI:10.1097/APO.0000000000000115
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    ABSTRACT: Aims: To identify the reasons for poor uptake of cataract surgery in a program of outreach screening and low-cost surgery in Pucheng County, a rural area in northwestern China. Methods: Detailed interviews with a semi-structured questionnaire were conducted by telephone or face-to-face for participants who had been advised to attend a low-cost cataract surgery program but did not schedule the surgery within 3 months after the initial screening. Results: Among 432 eligible subjects, 355 (82.2%) were interviewed (mean age 70.6 ± 6.6 years, 73.8% female). A total of 138 subjects (38.9%) were interviewed by phone and 217 (61.1%) were interviewed face-to-face. Lack of family support (n = 106, 29.9%) and failure to understand the need for surgery (n = 96, 27.0%) were the two main reasons for not undergoing cataract surgery. Other factors included fear of surgery (n = 62, 17.5%), lack of faith in doctors (n = 36, 10.1%), financial constraints (n = 25, 7.0%) and lack of transportation (n = 4, 1.1%). Conclusion: The principal barriers to low-cost cataract surgery uptake in rural China included lack of family support and failure to understand the need for surgery. Education targeting entire families to eliminate these barriers and development of community support systems at the family level are required to achieve greater uptake of low-cost cataract surgery programs in rural China.
    Ophthalmic epidemiology 04/2014; 21(3). DOI:10.3109/09286586.2014.903981 · 1.15 Impact Factor
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    Peter Heiner · Edoardo Ligabue · Alex Fan · Dennis Lam ·
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    ABSTRACT: To evaluate the safety and effectiveness of a single-piece hydrophobic acrylic intraocular lens (IOL) (enVista® MX60; Bausch and Lomb Incorporated, Rochester, NY, USA) following implantation to correct aphakia subsequent to extracapsular cataract extraction in adults. This was an open-label, non-interventional, observational study conducted in 19 university and private-practice settings in Europe and the Asia-Pacific region to investigate clinical outcomes of the MX60 IOL in standard practice. Eligible subjects were at least 18 years of age and had undergone standard phacoemulsification and extracapsular cataract extraction with implantation of the MX60 IOL. The primary safety endpoint was the occurrence of adverse events, and the primary effectiveness endpoints included visual and refractive outcomes and stability, with data collected up to 2 years post-procedure. In this multicenter study, pooled data of 255 eyes were collected and analyzed. Excellent visual and refractive outcomes and stability were demonstrated. At postoperative visit 4 (61-180 days postoperative), 62.2% of subjects achieved a Snellen best-corrected distance visual acuity (CDVA) of 20/20 (decimal 1.00), and 97.8% of subjects achieved a CDVA of 20/40 (decimal 0.50) or better. One eye (1.0%) underwent neodymium:yttrium aluminum garnet capsulotomy at 12 months post-procedure. No glistenings of any grade were reported for any subject at any visit. Adverse events were infrequent and were consistent with incidences generally reported with cataract surgery. This study, which enrolled all comers, provided evidence of the excellent safety and effectiveness of the MX60 IOL in standard practice. Favorable clinical outcomes included outstanding visual and refractive outcomes and stability. No glistenings were reported at any postoperative visit.
    Clinical ophthalmology (Auckland, N.Z.) 03/2014; 8:629-35. DOI:10.2147/OPTH.S56135
  • Mary Ho · David T L Liu · Alvin L. Young · Dennis S C Lam ·
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    ABSTRACT: Choroidal neovascularization (CNV) secondary to pathological myopia is an important cause of significant visual impairment in young adults. High myopia is particularly prevalent in Asian population. New scientific contributions have been made to the understanding of high myopia and myopic CNV. Treatment for myopic CNV has previously relied on photodynamic therapy, laser photocoagulation, and submacular surgery. The treatment outcomes from these modalities are, however, controversial. The introduction of antiangiogenic agents including bevacizumab and ranibizumab has brought the treatment of myopic CNV into a new era. The purpose of this review was to provide an overview of the natural history of myopic CNV, the prognostic factors, and the various treatment options including laser photocoagulation and photodynamic therapy, with particular attention on antiangiogenic agents.
    03/2014; 3(2):94-103. DOI:10.1097/APO.0000000000000017
  • Frank H P Lai · David T L Liu · Dennis S C Lam ·
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    ABSTRACT: The purpose of this article is to highlight evidence about the medical and surgical management of intermediate uveitis (IU). Updated understandings of the immunopathology of IU were reviewed in this retrospective literature review. Literature selection for this review was based on the PubMed database (National Library of Medicine) and OVID database (Wolters Kluwer). Articles deemed relevant were selected and highlighted. Intermediate uveitis is most often a benign form of uveitis. Since intermediate uveitis has been described in association with different systemic disorders, the initial diagnostic evaluation should serve to exclude masquerade syndromes and infectious diseases in which immunosuppression may be ineffective or contraindicated. Although the pathogenesis of intermediate uveitis is not fully understood, identification of proinflammatory molecules involved in the IU has contributed to the development and implementation of new therapies. Studies about the use of various immunosuppressants, biological agents and surgical treatment on IU have provided more evidence for managing IU. Nevertheless, corticosteroids remain the mainstay of treatment. The treatment options of intermediate uveitis are evolving, with the development of various immunosuppressants and biological agents. The management of intermediate uveitis should be tailored individually, based on specific causes of the disease and associated complications.
    11/2013; 2(6):375-387. DOI:10.1097/APO.0b013e3182a2c90b

  • Ophthalmology 10/2013; 120(10):e71-e72. DOI:10.1016/j.ophtha.2013.06.036 · 6.14 Impact Factor

  • Ophthalmology 07/2013; 120(7):e45-6. DOI:10.1016/j.ophtha.2013.03.008 · 6.14 Impact Factor
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    ABSTRACT: OBJECTIVE: To define the prevalence of blindness and visual impairment (VI) in people in rural Hainan using the rapid assessment of avoidable blindness (RAAB) and to report the outcomes of cataract surgery among the residents. DESIGN: Population-based, cross-sectional survey. PARTICIPANTS: A total of 6482 rural residents of the Hainan province. METHODS: A total of 136 clusters, each of which consisted of 50 people aged ≥50 years, were selected through probability-proportionate-to-size sampling. Door-to-door visits were performed by 2 outreach teams. Visual acuity (VA) was measured on site, and those with VA <6/18 in either eye were examined by an ophthalmologist. Causes of blindness and VI were determined. The causes of poor visual outcome after cataract surgery were evaluated. Information regarding barriers to receiving surgery was collected by trained interviewers. MAIN OUTCOME MEASURES: Prevalence and causes of blindness (VA <3/60), severe VI (SVI) (VA <6/60 but ≥3/60), and VI (VA <6/18 but ≥6/60) based on presenting VA (PVA) were assessed. Outcomes of cataract surgery performed in public and private hospitals and charitable organizations were compared. RESULTS: A total of 6482 subjects were examined (response rate, 95.3%). The sample prevalence of blindness was 4.4% (95% confidence interval [CI], 2.0-6.8). The prevalence of SVI and VI was 1.9% (95% CI, 0-4.3) and 9.9% (95% CI, 7.6-12.2), respectively. Age and sex were associated with increased prevalence of blindness, SVI, and VI. Overall, cataract accounted for approximately 60% of blindness and SVI. Of the 524 eyes that had received cataract surgery, 87.2% had intraocular lenses implanted, 21% had a poor visual outcome (PVA <6 /60), and 20% had a borderline visual outcome (PVA <6/18 but ≥6/60). Eyes that received surgery in charitable organizations had a higher rate of intraocular lens implantation and good visual outcome (VA ≥6/18) compared with eyes that were operated on elsewhere. CONCLUSIONS: The prevalence of blindness, SVI, and VI was high among rural residents in Hainan. Cataract remained the leading cause of avoidable blindness. Outcomes of cataract surgery performed in public hospitals were suboptimal. Quality-control initiatives should be introduced to improve cataract surgery outcomes. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
    Ophthalmology 05/2013; 120(11). DOI:10.1016/j.ophtha.2013.04.003 · 6.14 Impact Factor
  • Mary Ho · David T.L. Liu · Vesta C.K. Chan · Dennis S.C. Lam ·
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    ABSTRACT: PURPOSE: To measure choroidal thickness (CT) in myopic eyes using enhanced depth imaging (EDI). DESIGN: A cross-sectional study. PARTICIPANTS: Fifty-six consecutive patients with spherical equivalent refractive error of at least 6 diopters (D) were evaluated. METHODS: Enhanced depth imaging optical coherence tomography (OCT) images were obtained by positioning the spectral-domain OCT device close enough to the eye to acquire an enhanced signal of the choroidal layer. Choroidal depth was measured as the distance between the outer reflective retinal pigment epithelium (RPE) layer and the inner sclera border. Measurements were made in a horizontal fashion across the fovea at 500-μm intervals of the sections. The CT was measured at the subfoveal region in a horizontal fashion, 3 mm temporal to fovea and 3 mm nasal to fovea. MAIN OUTCOME MEASURES: Correlations among CT with age, refractive error in diopters, and visual acuity in logarithm of the minimum angle of resolution (logMAR) were analyzed with linear mixed models. RESULTS: The mean age of the 56 patients was 50.4 years (±2.03 years standard deviation; interquartile range [IQR], 42-62 years), and the mean refractive error was -8.7 D (IQR, -6.1 to -11 D). The mean subfoveal CT was 118 μm (±68 μm) and correlated negatively with age (P = 0.032) and refractive error (P = 0.011). Regression analysis suggested that subfoveal CT decreased by 11.9 μm for each decade of life and by 6.205 μm for each diopter of myopia. The subfoveal CT was inversely correlated with the logMAR visual acuity (P = 0.008), and visual acuity improved by 0.02 (logMAR) in a 10-μm increase in CT. CONCLUSIONS: Choroidal thickness decreases with age and severity of myopia. Visual acuity decreases in line with decreasing subfoveal CT. A reduction in CT is related to aging and the severity of myopia, whereas visual acuity depends on subfoveal CT. Our study supports the theory that choroidal abnormality may play a key role in the pathogenesis of myopic degeneration. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
    Ophthalmology 05/2013; 120(9). DOI:10.1016/j.ophtha.2013.02.005 · 6.14 Impact Factor
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    Xiao Ying Liang · Mingguang He · Dennis S C Lam ·

    05/2013; 2(3):141-142. DOI:10.1097/APO.0b013e318296cd99
  • Isabel Lai · Heather Mak · Gilda Lai · Marco Yu · Dennis S.C. Lam · Christopher K.S. Leung ·
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    ABSTRACT: OBJECTIVE: To investigate the use of swept-source optical coherence tomography (OCT) for measuring the area and degree of peripheral anterior synechia (PAS) involvement in patients with angle-closure glaucoma. DESIGN: Cross-sectional study. PARTICIPANTS: Twenty-three eyes with PAS (detected by indentation gonioscopy) from 20 patients with angle-closure glaucoma (20 eyes had primary angle-closure glaucoma and 3 eyes had angle-closure glaucoma secondary to chronic anterior uveitis [n = 2] and Axenfeld-Rieger syndrome [n = 1]). METHODS: The anterior chamber angles were evaluated with indentation gonioscopy and imaged by swept-source OCT (Casia OCT, Tomey, Nagoya, Japan) in room light and in the dark using the "angle analysis" protocol, which was composed of 128 radial B-scans each with 512 A-scans (16-mm scan length). The area and degree of PAS involvement were measured in each eye after manual detection of the scleral spur and the anterior irido-angle adhesion by 2 masked observers. The interobserver variability of the PAS measurements was calculated. MAIN OUTCOME MEASURES: The agreement of PAS assessment by gonioscopy and OCT, the area and the degree of PAS involvement, and the intraclass correlation coefficient (ICC) of interobserver PAS measurements. RESULTS: The area of PAS (mean ± standard deviation) was 20.8±16.9 mm(2) (range, 3.9-74.9 mm(2)), and the degree of PAS involvement was 186.5±79.9 degrees (range, 42-314 degrees). There was no difference in the area of PAS (P = 0.90) and the degree of PAS involvement (P = 0.95) between images obtained in room light and in the dark. The interobserver ICCs were 0.99 (95% confidence interval [CI], 0.98-1.00) for the area of PAS and 0.99 (95% CI, 0.97-1.00) for the degree of PAS involvement. There was good agreement of PAS assessment between gonioscopy and OCT images (kappa = 0.79; 95% CI, 0.67-0.91). CONCLUSIONS: Swept-source OCT allows visualization and reproducible measurements of the area and degree of PAS involvement, providing a new paradigm for evaluation of PAS progression and risk assessment for development of angle-closure glaucoma. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
    Ophthalmology 03/2013; 120(6). DOI:10.1016/j.ophtha.2012.12.006 · 6.14 Impact Factor
  • Hamish McKee · Cong Ye · Marco Yu · Shu Liu · Dennis S C Lam · Christopher K S Leung ·
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    ABSTRACT: Objective: To determine the visibility of the scleral spur (SS), Schwalbe's line (SL), and Schlemm's canal (SC) imaged by a swept-source optical coherence tomographer (OCT). Methods: One eye from each individual was randomly selected from 30 normal subjects and 30 patients with primary open-angle glaucoma for anterior segment imaging with a swept-source OCT. The angles were imaged with 2 protocols: (1) high-density (HD, a raster of 64 B-scans each with 512 A-scans over 8 mm) and (2) low-density scans (LD, 128 radial scans each with 512 A-scans over 16 mm). The visibility of the angle structures was determined by 2 masked observers and compared among the superior (90 degrees), nasal (0 degrees), inferior (270 degrees), and temporal (180 degrees) quadrants. Results: The interobserver agreement for assessment of visibility of the angle structures was high with agreement coefficients ranging between 0.769 and 0.987. The SS, SL, and SC were visible by both observers in 95% to 100%, 68% to 98%, and 12% to 42% of a total of 240 (4×60) quadrants in 60 HD images, respectively. The visibility was reduced in LD images (50% to 95%, 0% to 10%, and 0%, respectively). The temporal and nasal quadrants generally had superior visibility of the angle structures than the superior and inferior quadrants. Conclusions: The SS, SL, and SC could be identified with the swept-source OCT although their visibility varied with the scan location and scan density. The SS was best visualized, followed by the SL and then the SC in the OCT images.
    Journal of glaucoma 01/2013; 22(6). DOI:10.1097/IJG.0b013e31824485fa · 2.11 Impact Factor
  • Tsz Kin Ng · Dennis S C Lam · Herman S. Cheung ·
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    ABSTRACT: Retinal diseases, including glaucoma, retinitis pigmentosa, diabetic retinopathy, and age-related macular degeneration, are the leading causes of irreversible visual impairment and blindness in developed countries. Traditional and current treatment regimens are based on surgical or medical interventions to slow down the disease progression. However, the number of retinal cells would continue to diminish, and the diseases could not be completely cured. There is an emerging role of stem cells in retinal research. The stem cell therapy on retinal diseases is based on 2 theories: cell replacement therapy and neuroprotective effect. The former hypothesizes that new retinal cells could be regenerated from stem cells to substitute the damaged cells in the diseased retina, whereas the latter believes that the paracrine effects of stem cells modulate the microenvironments of the diseased retina so as to protect the retinal neurons. This article summarizes the choice of stem cells in retinal research. Moreover, the current progress of retinal research on stem cells and the clinical applications of stem cells on retinal diseases are reviewed. In addition, potential challenges and future prospects of retinal stem cell research are discussed.
    01/2013; 2(1):57-63. DOI:10.1097/APO.0b013e31827e3e5d
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    ABSTRACT: Aims To examine the additive effect of the z-4 microsatellite polymorphism of aldose reductase gene (ALR2) and glycaemic control on risk of cataract in a prospective cohort of Chinese type 2 diabetic patients. Methods The (CA)n microsatellite polymorphism of ALR2 was determined using PCR followed by capillary gel electrophoresis. Cataract was defined by presence of lens opacity on direct ophthalmoscopy or history of cataract surgery. A non-linear curve approach was used to identify the threshold of glycated hemoglobin (HbA1c) at which the odds ratio (OR) for cataract started to increase. The association of z-4 allele with cataract, above and below this threshold, was assessed using multiple logistic regression analysis. Results Of the 5,823 patients analyzed, 28.1% had cataracts. After adjusting for conventional risk factors and using non-z-4 carriers with HbA1c < 8.0 % as referent group(n = 3173), the OR(95% confidence intervals) for cataract was highest in z-4 carriers with HbA1c≥ 8.0%[1.43(1.05-1.96), n = 244], compared to non-z-4 carriers with HbA1c≥ 8.0[1.27(1.10-1.47), n = 1836] and z-4 carriers with HbA1c < 8.0%[1.01(0.77-1.29), n = 420, Ptrend < 0.001]. This additive association remained significant after additional adjustments for drug use (Ptrend = 0.002) and renal function (Ptrend = 0.01). Conclusions In type 2 diabetic patients with suboptimal glycaemic control, the z-4 allele of ALR2 (CA)n polymorphism was independently associated with increased susceptibility to cataracts.
    Journal of diabetes and its complications 01/2013; 28(2). DOI:10.1016/j.jdiacomp.2013.10.011 · 3.01 Impact Factor
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    ABSTRACT: Background: Lipoprotein lipase (LPL) promotes the binding and transfer of apolipoprotein E (ApoE) lipoprotein particle components to cells. Age-related macular degeneration (AMD), characterized by drusen, containing lipids, is reportedly associated with a lower frequency of the ApoE 4 allele than are control subjects. Because of the functional association of LPL and ApoE, we sought to examine whether an LPL polymorphism affects AMD risk. The common LPL alteration Ser447Ter decreases triglyceride levels and risk of cardiovascular disease. Methods: We genotyped this LPL polymorphism in 140 unrelated Hong Kong Chinese AMD patients and 100 elderly normal controls using polymerase chain reaction followed by Mnl I restriction enzyme digestion. Results: There was no difference in frequency of the 447Ter allele between patients (11.4%) and controls (11.0%). Conclusions: Either LPL does not play a role in AMD, or its effect is not revealed by this polymorphism or in this ethnic group.

Publication Stats

14k Citations
2,769.20 Total Impact Points


  • 2015
    • Sun Yat-Sen University
      • State Key Laboratory of Oncology
      Shengcheng, Guangdong, China
  • 1995-2014
    • The Chinese University of Hong Kong
      • Department of Ophthalmology and Visual Sciences
      Hong Kong, Hong Kong
  • 2001-2012
    • Caritas Hong Kong
      Chiu-lung, Kowloon City, Hong Kong
  • 2008-2010
    • Shantou University
      Swatow, Guangdong, China
  • 2009
    • Hong Kong Sanatorium & Hospital
      Hong Kong, Hong Kong
  • 1994-2009
    • Prince of Wales Hospital, Hong Kong
      Chiu-lung, Kowloon City, Hong Kong
  • 2006
    • Fudan University
      Shanghai, Shanghai Shi, China
  • 2005-2006
    • Alice Ho Miu Ling Nethersole Hospital
      Ch’üan-wan, Tsuen Wan, Hong Kong
  • 2004-2006
    • Hong Kong SAR Government
      Hong Kong, Hong Kong
  • 2001-2004
    • Christian Hospital
      Saint Louis, Michigan, United States
  • 2003
    • Tuen Mun Hospital
      Hong Kong, Hong Kong
  • 2002
    • City University London
      • Applied Vision Research Centre
      Londinium, England, United Kingdom
  • 2001-2002
    • Hong Kong Hospital Authority
      Hong Kong, Hong Kong