Publications by authors named "Alfred Gan"
Introduction: The concomitant impact of visual impairment (VI) and cognitive impairment (CI) on health-related quality of life (HRQoL) in older adults is unclear. We aimed to determine the synergistic effect of baseline VI and CI on HRQoL decline at 6 years in multiethnic Asians.
Methods: We included Chinese, Malay, and Indian adults aged ≥60 years who participated in baseline (2004-2011) and 6-year (2011-2017) follow-up visits of the Singapore Epidemiology of Eye Diseases Study, a population-based cohort study in Singapore.
Genetic Variability of Complement Factor H Has Ethnicity-Specific Associations With Choroidal Thickness.
Invest Ophthalmol Vis Sci
February 2023
Purpose: To identify genetic alleles associated with differences in choroidal thickness (CT) in a population-based multiethnic Asian cohort.
Methods: A population-based multiethnic Asian cohort without retinal pathology was subjected to spectral-domain OCT (SD-OCT) and genotyping of risk alleles in CFH, VIPR2, ARMS2, and CETP. Subfoveal choroidal thickness (SFCT) values were assessed from SD-OCT, and associations with the risk alleles were determined for each cohort.
Purpose: To compare quality of life (QoL) between patients who receive bilateral small-incision lenticule extraction (SMILE) or laser in situ keratomileusis (LASIK) vs bilateral sequential SMILE-LASIK (BSSL) surgery.
Setting: Singapore National Eye Centre, Singapore.
Design: Retrospective cohort study.
Prcis: In this population-based, cross-sectional study of Indian and Malay adults in Singapore aged 40 years or above, intermediate or high risk of obstructive sleep apnea (OSA) was associated with 50% higher odds of having glaucoma.
Background/aims: The relationship between OSA and glaucoma is unclear. We assessed the association between the risk of OSA and glaucoma in an Asian population.
To determine the differential impact of the irreversible eye diseases on vision-related quality of life (VRQoL) in a multi-ethnic Asian population. 2652 participants from the Singapore Epidemiology of Eye Disease Study, with any of the following early and late-stage eye conditions including age-related macular degeneration (AMD, n = 158), diabetic retinopathy (DR, n = 105; non vision threatening [non-VTDR]; VTDR), glaucoma (n = 57) and myopic macular degeneration (MMD, n = 106), or none of the above (controls, 2226 [83.9%]) were included.
View Article and Find Full Text PDFBackground: Diagnostic performance of optical coherence tomography (OCT) to detect Alzheimer's disease (AD) and mild cognitive impairment (MCI) remains limited. We assessed whether compensating the circumpapillary retinal nerve fiber layer (cpRNFL) thickness for multiple demographic and anatomical factors as well as the combination of macular layers improves the detection of MCI and AD.
Methods: This cross-sectional study of 62 AD (n = 92 eyes), 108 MCI (n = 158 eyes), and 55 cognitively normal control (n = 86 eyes) participants.
Sensory impairments and sarcopenia are both highly prevalent age-related conditions, with the former having been postulated to contribute to the pathogenesis of the latter condition. Confirming this hypothesis may therefore help to better inform strategies for early treatment and intervention of sarcopenia. We performed a systematic review of the current literature examining the relationships between four major sensory impairments [vision (VI), hearing (HI), smell (SI), and taste (TI)] with (i) sarcopenia; and (ii) its associated components (low handgrip strength, slow gait speed, and low muscle mass).
View Article and Find Full Text PDFPurpose: To use optical coherence tomography angiography (OCTA) parameters from both the retinal and choroidal microvasculature to detect the presence and severity of diabetic retinopathy (DR).
Method: This is a cross-sectional case-control study. OCTA parameters from retinal vasculature, fovea avascular zone (FAZ) and choriocapillaris were evaluated from 3×3 mm fovea-centred scans.
Aims: To examine the relationship between vision impairment (VI) and employment outcomes in a multiethnic Asian population.
Methods: We included 7608 Asian individuals aged ≥40 years (mean (SD) age: 58.4 (10.
Introduction: We investigated the knowledge, attitudes and practice (KAP) towards coronavirus disease 2019 (COVID-19) and its related preventive measures in Singaporeans aged ≥60 years.
Methods: This was a population-based, cross-sectional, mixed-methods study (13 May 2020-9 June 2020) of participants aged ≥ 60 years. Self-reported KAP about ten symptoms and six government-endorsed preventive measures related to COVID-19 were evaluated.
Purpose: To evaluate whether optical coherence tomography (OCT) can determine polypoidal lesion (PL) perfusion in polypoidal choroidal vasculopathy eyes after 12 months of aflibercept monotherapy. Polypoidal lesion perfusion status, assessed by indocyanine green angiography, is an important anatomical outcome in polypoidal choroidal vasculopathy management.
Methods: Post hoc data from a prospective randomized, open-label, study in eyes with polypoidal choroidal vasculopathy undergoing monotherapy with aflibercept evaluated PL perfusion status based on indocyanine green angiography (gold standard) and OCT features from baseline to 12 months.
Importance: A glaucoma-specific instrument for estimating utilities across the spectrum of glaucoma severity is currently lacking, hindering the assessment of the cost-effectiveness of glaucoma treatments.
Objective: To develop and validate the preference-based Glaucoma Utility Instrument (Glau-U) and to ascertain the association between Glau-U utilities and severity of glaucoma and vision impairment.
Design, Setting, And Participants: This cross-sectional study was conducted in 2 stages at the Singapore National Eye Centre glaucoma clinics.
Purpose: To investigate the prevalence of dual sensory impairment (DSI), its associated factors and relationship with health-related quality of life (HR-QoL) in residential care facilities (RCF) in Singapore.
Methods: This was a cross-sectional study of 123 residents aged ≥40 years from six RCFs, conducted between 2016 and 2018. DSI was defined as concomitant presenting visual acuity (better-eye) >0.
Background/aims: To examine the relationship between macular perfusion, as assessed using optical coherence tomography angiography (OCTA), and long-term visual outcome after surgical repair of macula-off rhegmatogenous retinal detachment (RRD).
Methods: A prospective study of 29 patients who had undergone successful surgical repair of macula-off RRD. OCTA imaging was performed at month 3 and repeated at months 6 and 12 after surgery.
Background: We examined the associations between the 6-year incidence of age-related macular degeneration (AMD) and vision-related quality of life (VRQoL), and the contribution of presenting visual acuity (VA), in an Asian population.
Methods: Fundus images from the Singapore Chinese Eye Study, a population-based cohort study (baseline: 2009-2011; follow-up: 2015-2017), were graded using a modified Wisconsin age-related maculopathy grading system. Incident AMD was defined as no baseline AMD in both eyes and early/late AMD in the worse eye at follow-up.
Background: The relationship between self-reported visual disability and cognitive impairment in older individuals is unclear.
Objective: To determine the relationship of vision-specific functioning (VSF), vision-specific mobility (VSM) and visual acuity (VA) with clinically assessed cognitive impairment in the Epidemiology of Dementia in Singapore study.
Design: Cross-sectional.
Purpose: To prospectively evaluate whether diabetic macular ischemia detected with coherence tomography angiography (OCTA) is associated with change in functional outcomes over a period of one year.
Methods: This is a one-year prospective, observational study that included 56 eyes with varying levels of diabetic retinopathy. All participants underwent best corrected visual acuity evaluation, swept-source OCTA and microperimetry at baseline and repeated at one year.
Topic: Visual impairment (VI) and cognitive impairment (CIM) are prevalent age-related conditions that impose substantial burden on the society. Findings on the hypothesized bidirectional association of VI and CIM remains equivocal. Hence, we conducted a systematic review and meta-analysis to examine this bidirectional relationship.
View Article and Find Full Text PDFTo describe the rationale, design and methodology of a geographically-representative and population-based study investigating the epidemiology, impact, personal and economic burden of age-related eye diseases, declining visual and other sensory systems in Asians aged >60 years in Singapore.PIONEER (The PopulatION HEalth and Eye Disease PRofilE in Elderly Singaporeans Study) is currently a cross-sectional study targeting 3152 Chinese, Malay and Indian adults who are Singapore citizens or permanent residents aged 60 years and older living across Singapore. The study is intended to be longitudinal, with several waves of data planned to be collected in the future.
View Article and Find Full Text PDFPurpose: A validated questionnaire assessing diabetic retinopathy (DR)- and diabetic macular edema (DME)-related knowledge (K) and attitudes (A) is lacking. We developed and validated the Diabetic Retinopathy Knowledge and Attitudes (DRKA) questionnaire and explored the association between K and A and the self-reported difficulty accessing DR-related information (hereafter referred to as Access).
Methods: In this mixed-methods study, eight focus groups with 36 people with DR or DME (mean age, 60.
Purpose: To evaluate associations between choroidal thickness and features of polypoidal choroidal vasculopathy (PCV) lesions based on multimodal imaging.
Methods: This cross-sectional analysis included treatment-naive PCV eyes from a prospectively recruited observational cohort. Associations between of subfoveal choroidal thickness (SFCT) and qualitative and quantitative morphologic features of PCV lesions on color fundus photographs, indocyanine green and fluorescein angiography, and spectral-domain optical coherence tomography were evaluated.
Purpose: Evaluate efficiency, precision, and validity of RetCAT, which comprises ten diabetic retinopathy (DR) quality of life (QoL) computerized adaptive tests (CATs).
Methods: In this cross-sectional clinical study, 183 English and/or Mandarin-speaking participants with DR (mean age ± standard deviation [SD] 56.4 ± 11.
Purpose: To determine the rates and develop an initial risk prediction model for nonadherence to post screening ophthalmic referral (PSOR) in type 2 diabetes mellitus (T2DM) patients attending a national diabetic retinopathy screening program in Singapore.
Methods: Data from 2387 patients with T2DM (mean [standard deviation] age: 66.5 [11] years; 52.
Purpose: The purpose of this study was to determine the rates of, and factors associated with, eyecare utilization and spectacle affordability among Singaporeans with vision impairment (VI).
Methods: We included adults with VI from their second visit of the Singapore Epidemiology of Eye Disease Study. Data on eyecare utilization and spectacle affordability were collected.
Purpose: Visual impairment (VI) can have a detrimental impact on vision-related quality of life (VRQoL), but it is still unclear how this relationship varies with age across the VI spectrum. We determined the age-stratified, cross-sectional, and longitudinal associations between VI severity and VRQoL.
Design: The baseline and follow-up Singapore Chinese Eye Studies (SCES-1/-2; 2009-2011 and 2015-2017).