Publications by authors named "Colin S Tan"

177 Publications

Assessment of the Macular Microvasculature in High Myopes With Swept Source Optical Coherence Tomographic Angiography.

Front Med (Lausanne) 2021 17;8:619767. Epub 2021 May 17.

Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore.

The risk of pathologic myopia (PM) increases with worsening myopia and may be related to retinal microvasculature alterations. To evaluate this, we analyzed the macular microvasculature of myopes with swept source-optical coherence tomographic angiography (SS-OCTA) in adolescent and young adult Singaporeans. This is a prevalent case-control study including 93 young Chinese from the Strabismus, Amblyopia and Refractive error in Singaporean children (STARS, = 45) study and the Singapore Cohort Study of Risk Factors for Myopia (SCORM, = 48) studies. Macular vessel density (VD) measurements were obtained from 3 × 3 mm SS-OCTA scans and independently assessed using ImageJ. These measurements were compared between individuals with non-high myopia [non-HM, = 40; SE >-5.0 diopter (D)] and HM (SE ≤-5.0D, = 53). The mean macular VD was 40.9 ± 0.6% and 38.2 ± 0.5% in the non-HM and HM, groups, respectively ( = 0.01 adjusted for age and gender). Mean FAZ area in the superficial layer was 0.22 ± 0.02 mm in the HM group, which was smaller compared to non-HM group (0.32 ± 0.03 mm, = 0.04). Mean deep FAZ area was similar between the two groups (0.45 ± 0.03 mm and 0.48 ± 0.04 mm in the HM and non-HM groups, respectively, = 0.70). VD was lower and superficial FAZ area was smaller, in adolescents and young adults with HM compared to non-HM. These findings require validation in prospective studies to assess their impact on the subsequent development of PM.
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http://dx.doi.org/10.3389/fmed.2021.619767DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8165745PMC
May 2021

Comparison of Polypoidal Choroidal Vasculopathy Lesion Sizes Measured on Multicolor Imaging and Indocyanine Green Angiography.

Transl Vis Sci Technol 2021 Feb;10(2):35

National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore.

Purpose: To evaluate the areas of lesion components of polypoidal choroidal vasculopathy (PCV) measured using multicolor imaging compared to indocyanine green angiography (ICGA).

Methods: In a prospective study of 50 consecutive treatment-naïve PCV patients, multicolor imaging and ICGA were performed. The images were independently graded by reading center-certified retinal specialists to confirm the diagnosis of PCV and identify lesion components. The areas of the respective lesion components were compared.

Results: The mean age of the participants was 67.8 years. PCV was diagnosed in 96% of eyes using multicolor imaging. The mean numbers of polypoidal lesions identified using ICGA and multicolor were 4.0 and 2.1, respectively (P < 0.001), with mean total polypoidal lesion areas of 0.32 mm2 versus 0.30 mm2 (P = 0.727). The area of the branching vascular network (BVN) on ICGA was 7.8 mm2 compared to 5.7 mm2 on multicolor imaging (P = 0.289). Patients with four or more polypoidal lesions on ICGA had larger differences in total lesion area between ICGA and multicolor imaging (4.07 vs. -0.70 mm2, p = 0.039). Those with total lesion area ≥ 2.0 mm2 on ICGA had larger differences in mean polypoidal lesion number compared to those with smaller areas (2.2 vs. 0.5; P = 0.026).

Conclusions: Multicolor imaging is a useful, noninvasive adjunct for detecting PCV lesion components, revealing lesion areas similar to but generally smaller than those seen on ICGA. This is important to consider when making treatment decisions with different imaging modalities.

Translational Relevance: New features seen on multicolor imaging can aid in the diagnosis and treatment of PCV.
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http://dx.doi.org/10.1167/tvst.10.2.35DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7910643PMC
February 2021

RANIBIZUMAB WITH OR WITHOUT VERTEPORFIN PHOTODYNAMIC THERAPY FOR POLYPOIDAL CHOROIDAL VASCULOPATHY: Predictors of Visual and Anatomical Response in the EVEREST II Study.

Retina 2021 Feb;41(2):387-392

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.

Purpose: To evaluate the demographic and imaging factors at baseline and Month 3 (M3) that predict visual or anatomical responses at Month 12 (M12) in the EVEREST-II study for polypoidal choroidal vasculopathy.

Methods: Post-hoc analysis of 322 participants in the EVEREST-II study. Patient factors, best-corrected visual acuity (BCVA), treatment, and imaging parameters at baseline and M3 were evaluated with respect to outcomes at M12 using univariate and multivariable analysis.

Results: Younger age (P < 0.001) and lower baseline BCVA (P < 0.001) were associated with higher BCVA gains at M12. Smaller baseline polypoidal lesion area was associated with higher BCVA gains at M12 only in the ranibizumab monotherapy arm (P = 0.008). Central subfield thickness at M3, area of branching vascular network at M3, BCVA at M3, and age were associated with change in BCVA from M3 at M12. Higher odds of fluid-free retina at M12 were associated with lower baseline central subfield thickness (P = 0.006), treatment with combination therapy (baseline and M3 models; P < 0.001), and absence of subretinal fluid at M3 (P < 0.001).

Conclusion: Several imaging parameters at baseline and M3 can predict treatment outcome. The interaction between treatment arm and total polypoidal lesion area suggests this feature may assist selecting between initial ranibizumab monotherapy or combination therapy.
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http://dx.doi.org/10.1097/IAE.0000000000002902DOI Listing
February 2021

Artificial intelligence for teleophthalmology-based diabetic retinopathy screening in a national programme: an economic analysis modelling study.

Lancet Digit Health 2020 05 23;2(5):e240-e249. Epub 2020 Apr 23.

Singapore Eye Research Institute, Singapore National Eye Centre, Singapore; Tan Tock Seng Hospital, National Healthcare Group, Singapore; State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yet-Sen University, Guangzhou, China. Electronic address:

Background: Deep learning is a novel machine learning technique that has been shown to be as effective as human graders in detecting diabetic retinopathy from fundus photographs. We used a cost-minimisation analysis to evaluate the potential savings of two deep learning approaches as compared with the current human assessment: a semi-automated deep learning model as a triage filter before secondary human assessment; and a fully automated deep learning model without human assessment.

Methods: In this economic analysis modelling study, using 39 006 consecutive patients with diabetes in a national diabetic retinopathy screening programme in Singapore in 2015, we used a decision tree model and TreeAge Pro to compare the actual cost of screening this cohort with human graders against the simulated cost for semi-automated and fully automated screening models. Model parameters included diabetic retinopathy prevalence rates, diabetic retinopathy screening costs under each screening model, cost of medical consultation, and diagnostic performance (ie, sensitivity and specificity). The primary outcome was total cost for each screening model. Deterministic sensitivity analyses were done to gauge the sensitivity of the results to key model assumptions.

Findings: From the health system perspective, the semi-automated screening model was the least expensive of the three models, at US$62 per patient per year. The fully automated model was $66 per patient per year, and the human assessment model was $77 per patient per year. The savings to the Singapore health system associated with switching to the semi-automated model are estimated to be $489 000, which is roughly 20% of the current annual screening cost. By 2050, Singapore is projected to have 1 million people with diabetes; at this time, the estimated annual savings would be $15 million.

Interpretation: This study provides a strong economic rationale for using deep learning systems as an assistive tool to screen for diabetic retinopathy.

Funding: Ministry of Health, Singapore.
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http://dx.doi.org/10.1016/S2589-7500(20)30060-1DOI Listing
May 2020

Predictors of persistent disease activity following anti-VEGF loading dose for nAMD patients in Singapore: the DIALS study.

BMC Ophthalmol 2020 Aug 6;20(1):324. Epub 2020 Aug 6.

Novartis (Singapore) Private Limited, Singapore, Singapore.

Background: To determine the frequency of persistent disease activity following 3 loading doses of anti- vascular endothelial growth factor (VEGF) agents, and the anatomic and demographic predictors of early persistent disease activity among patients with neovascular age-related macular degeneration (nAMD).

Methods: In a retrospective real-world cohort study, 281 consecutive patients with nAMD were reviewed at baseline and after 3 anti-VEGF injections for pre-defined indicators of disease activity. Optical coherence tomography (OCT) features such as subretinal fluid, intraretinal cysts and intraretinal fluid were assessed by reading-center certified graders. Multiple logistic regression was performed on demographic and anatomic factors.

Results: At month 3, 66.1% of patients had persistent disease activity. The best-corrected visual acuity (BCVA) improvement was 0.16 LogMAR for those with no disease activity compared to 0 for patients with persistent activity (p < 0.001). The significant risk factors for persistent activity at 3 months were male gender (odds ratio [OR] 0.54, 95% confidence interval [CI] 0.32-0.93, p = 0.025), intraretinal cysts at baseline (OR 2.95, 95% CI 1.67-5.20, p < 0.001) and subretinal fluid at baseline (OR 3.17, 95% CI 1.62-6.18, p = 0.002). At 3 months, 58% of patients had features of activity on OCT. Patients with intraretinal cysts and intraretinal fluid at baseline had worse BCVA at month 3 compared to patients without these OCT features (0.69 vs. 0.43, p < 0.001, and 0.62 vs. 0.43, p < 0.001, respectively).

Conclusions: In a real-world study, 66.1% of nAMD patients have persistent disease activity after the initial loading dose, with poorer BCVA compared to those without. Baseline OCT features (intraretinal cysts and subretinal fluid) are useful predictors of persistent disease activity at month 3.
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http://dx.doi.org/10.1186/s12886-020-01582-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7409440PMC
August 2020

Comparison of Ranibizumab With or Without Verteporfin Photodynamic Therapy for Polypoidal Choroidal Vasculopathy: The EVEREST II Randomized Clinical Trial.

JAMA Ophthalmol 2020 09;138(9):935-942

Eye & Retina Surgeons, Camden Medical Centre, Singapore.

Importance: The 2-year efficacy and safety of combination therapy of ranibizumab administered together with verteporfin photodynamic therapy (vPDT) compared with ranibizumab monotherapy in participants with polypoidal choroidal vasculopathy (PCV) are unclear.

Objective: To compare treatment outcomes of ranibizumab, 0.5 mg, plus prompt vPDT combination therapy with ranibizumab, 0.5 mg, monotherapy in participants with PCV for 24 months.

Design, Setting, And Participants: This 24-month, phase IV, double-masked, multicenter, randomized clinical trial (EVEREST II) was conducted among Asian participants from August 7, 2013, to March 2, 2017, with symptomatic macular PCV confirmed using indocyanine green angiography.

Interventions: Participants (N = 322) were randomized 1:1 to ranibizumab, 0.5 mg, plus vPDT (combination therapy group; n = 168) or ranibizumab, 0.5 mg, plus sham PDT (monotherapy group; n = 154). All participants received 3 consecutive monthly ranibizumab injections, followed by a pro re nata regimen. Participants also received vPDT (combination group) or sham PDT (monotherapy group) on day 1, followed by a pro re nata regimen based on the presence of active polypoidal lesions.

Main Outcomes And Measures: Evaluation of combination therapy vs monotherapy at 24 months in key clinical outcomes, treatment exposure, and safety. Polypoidal lesion regression was defined as the absence of indocyanine green hyperfluorescence of polypoidal lesions.

Results: Among 322 participants (mean [SD] age, 68.1 [8.8] years; 225 [69.9%] male), the adjusted mean best-corrected visual acuity (BCVA) gains at month 24 were 9.6 letters in the combination therapy group and 5.5 letters in the monotherapy group (mean difference, 4.1 letters; 95% CI, 1.0-7.2 letters; P = .005), demonstrating that combination therapy was superior to monotherapy by the BCVA change from baseline to month 24. Combination therapy was superior to monotherapy in terms of complete polypoidal lesion regression at month 24 (81 of 143 [56.6%] vs 23 of 86 [26.7%] participants; P < .001). Participants in the combination group received fewer ranibizumab injections (median, 6.0 [interquartile range (IQR), 4.0-11.0]) than the monotherapy group (median, 12.0 [IQR, 7.0-17.0]) up to month 24. The combination group required a median of 2.0 (IQR, 1.0-3.0) vPDT treatments for 24 months, with 75 of 168 participants (44.6%) requiring only 1 vPDT treatment.

Conclusions And Relevance: The 24-month data findings confirm that ranibizumab therapy, given as monotherapy or in combination with vPDT, is efficacious and safe for treatment of PCV. Combination therapy with vPDT added to ranibizumab achieved superior BCVA gain, increased odds of complete polypoidal lesion regression, and fewer treatment episodes compared with ranibizumab monotherapy.

Trial Registration: ClinicalTrials.gov Identifier: NCT01846273.
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http://dx.doi.org/10.1001/jamaophthalmol.2020.2443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7366282PMC
September 2020

Optical Coherence Tomography Angiography as an Important Diagnostic Tool for Amblyopia.

JAMA Ophthalmol 2020 08;138(8):865-866

Fundus Image Reading Centre, National Healthcare Group Eye Institute, Singapore.

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http://dx.doi.org/10.1001/jamaophthalmol.2020.2219DOI Listing
August 2020

Use of Smartphones to Detect Diabetic Retinopathy: Scoping Review and Meta-Analysis of Diagnostic Test Accuracy Studies.

J Med Internet Res 2020 05 15;22(5):e16658. Epub 2020 May 15.

Family Medicine and Primary Care, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.

Background: Diabetic retinopathy (DR), a common complication of diabetes mellitus, is the leading cause of impaired vision in adults worldwide. Smartphone ophthalmoscopy involves using a smartphone camera for digital retinal imaging. Utilizing smartphones to detect DR is potentially more affordable, accessible, and easier to use than conventional methods.

Objective: This study aimed to determine the diagnostic accuracy of various smartphone ophthalmoscopy approaches for detecting DR in diabetic patients.

Methods: We performed an electronic search on the Medical Literature Analysis and Retrieval System Online (MEDLINE), EMBASE, and Cochrane Library for literature published from January 2000 to November 2018. We included studies involving diabetic patients, which compared the diagnostic accuracy of smartphone ophthalmoscopy for detecting DR to an accurate or commonly employed reference standard, such as indirect ophthalmoscopy, slit-lamp biomicroscopy, and tabletop fundus photography. Two reviewers independently screened studies against the inclusion criteria, extracted data, and assessed the quality of included studies using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, with disagreements resolved via consensus. Sensitivity and specificity were pooled using the random effects model. A summary receiver operating characteristic (SROC) curve was constructed. This review is reported in line with the Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy Studies guidelines.

Results: In all, nine studies involving 1430 participants were included. Most studies were of high quality, except one study with limited applicability because of its reference standard. The pooled sensitivity and specificity for detecting any DR was 87% (95% CI 74%-94%) and 94% (95% CI 81%-98%); mild nonproliferative DR (NPDR) was 39% (95% CI 10%-79%) and 95% (95% CI 91%-98%); moderate NPDR was 71% (95% CI 57%-81%) and 95% (95% CI 88%-98%); severe NPDR was 80% (95% CI 49%-94%) and 97% (95% CI 88%-99%); proliferative DR (PDR) was 92% (95% CI 79%-97%) and 99% (95% CI 96%-99%); diabetic macular edema was 79% (95% CI 63%-89%) and 93% (95% CI 82%-97%); and referral-warranted DR was 91% (95% CI 86%-94%) and 89% (95% CI 56%-98%). The area under SROC curve ranged from 0.879 to 0.979. The diagnostic odds ratio ranged from 11.3 to 1225.

Conclusions: We found heterogeneous evidence showing that smartphone ophthalmoscopy performs well in detecting DR. The diagnostic accuracy for PDR was highest. Future studies should standardize reference criteria and classification criteria and evaluate other available forms of smartphone ophthalmoscopy in primary care settings.
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http://dx.doi.org/10.2196/16658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7316182PMC
May 2020

Comparing efficacy of reduced-fluence and standard-fluence photodynamic therapy in the treatment of polypoidal choroidal vasculopathy.

BMC Ophthalmol 2020 Apr 15;20(1):150. Epub 2020 Apr 15.

National Healthcare Group Eye Institute, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore.

Background: The EVEREST II study reported superior polyp closure rates and visual outcomes using combination standard photodynamic therapy (PDT) with intravitreal ranibizumab in the treatment of polypoidal choroidal vasculopathy (PCV). The optimal PDT protocol remains controversial and it is postulated that less intensive PDT strategies may reduce complications. We aimed to compare the efficacy of reduced and standard-fluence PDT.

Methods: Case-control review of 38 consecutive PDT-naïve macular PCV patients who underwent verteporfin PDT using one of two PDT regimens at a tertiary referral centre in an Asian population. Comparison of outcomes between standard-fluence PDT (light dose, 50 J/cm2; dose rate, 600 mW/cm2; wavelength, 689 nm PDT applied to the treatment eye for 83 s) and reduced-fluence PDT (light dose, 25 J/cm2; dose rate, 600 mW/cm2; wavelength, 689 nm PDT applied to the treatment eye for 42 s). Primary outcome measure was best corrected LogMAR visual acuity (VA). Secondary outcome measures included OCT measurements such as central retinal thickness (CRT), height of subfoveal sub-retinal fluid (SRF), central choroid thickness (CCT), mean number of PDT treatments needed, mean number of anti-VEGF injections needed, polyp closure and recurrence rates.

Results: Of these 38 eyes of 38 patients, an equal number of eyes (19 in each arm) were treated with standard-fluence and reduced-fluence PDT. Mean letter gain at 12 months for the standard-fluence group was 6.0 compared to 4.3 letters for the reduced-fluence group (p = 0.61). Similar results were observed at all time points. There was no statistically significant difference between the retinal and choroidal anatomical OCT outcomes, rates of polyp closure and recurrences between the two PDT regimens.

Conclusions: Reduced-fluence PDT was comparable to standard-fluence PDT in the treatment of PCV in terms of visual gains, clinical and anatomical OCT outcomes.
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http://dx.doi.org/10.1186/s12886-020-01419-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7161176PMC
April 2020

Wide-field angiography in retinal vein occlusions.

Int J Retina Vitreous 2019 12;5(Suppl 1):18. Epub 2019 Dec 12.

5Doheny Eye Institute, University of California, Los Angeles, CA USA.

Background: Retinal vein occlusion (RVO) is the second most common retinal vascular disease after diabetic retinopathy. It can result in significant visual loss from complications like macula edema, retinal and iris neovascularization, and vitreous hemorrhage. Recently, ultra-widefield imaging (UWF) has been developed for posterior pole visualization and has shown to be useful in the evaluation and treatment of RVO.

Main Text: Ultra-widefield imaging (UWF) imaging allows for visualization of the retina up to an angle of 200°. This is especially important in detecting peripheral retinal pathologies, especially in retinal conditions such as RVO, where the disease process affects the peripheral as well as central retina. In particular, retinal non-perfusion in RVO is a risk factor for neovascularization. Various techniques, such as ischemic index and stereographic projection, have been described to assess areas of ischemia on UWF images. Retinal non-perfusion has an impact on disease complications, such as macular edema, and retinal and iris neovascularization. Retinal non-perfusion also has implications on disease response, including visual acuity, reduction in retinal edema and treatment burden.

Conclusion: Ultra-widefield imaging (UWF) imaging plays an important role in the assessment and management of RVO, especially in measuring retinal non-perfusion in the peripheries.
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http://dx.doi.org/10.1186/s40942-019-0163-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6907103PMC
December 2019

Impact of refractive error and choroidal thickness on choroidal vascular density.

Photodiagnosis Photodyn Ther 2020 Mar 19;29:101626. Epub 2019 Dec 19.

National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore, Singapore; Fundus Image Reading Center, National Healthcare Group Eye Institute, Singapore, Singapore. Electronic address:

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http://dx.doi.org/10.1016/j.pdpdt.2019.101626DOI Listing
March 2020

Use of smartphones for detecting diabetic retinopathy: a protocol for a scoping review of diagnostic test accuracy studies.

BMJ Open 2019 12 8;9(12):e028811. Epub 2019 Dec 8.

Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore

Introduction: Diabetic retinopathy (DR) is a common microvascular complication of diabetes mellitus and the leading cause of impaired vision in adults worldwide. Early detection and treatment for DR could improve patient outcomes. Traditional methods of detecting DR include the gold standard Early Treatment Diabetic Retinopathy Study seven standard fields fundus photography, ophthalmoscopy and slit-lamp biomicroscopy. These modalities can be expensive, difficult to access and require involvement of specialised healthcare professionals. With the development of mobile phone technology, there is a growing interest in their use for DR identification as this approach is potentially more affordable, accessible and easier to use. Smartphones can be employed in a variety of ways for ophthalmoscopy including the use of smartphone camera, various attachments and artificial intelligence for obtaining and grading of retinal images. The aim of this scoping review is to determine the diagnostic test accuracy of various smartphone ophthalmoscopy approaches for detecting DR in diabetic patients.

Methods And Analysis: We will perform an electronic search of MEDLINE, Embase and Cochrane Library for literature published from 2000 onwards. Two reviewers will independently analyse studies for eligibility and assess study quality using the QUADAS-2 tool. Data for a 2⨉2 contingency table will be extracted. If possible, we will pool sensitivity and specificity data using the random-effects model and construct a summary receiver operating characteristic curve. In case of high heterogeneity, we will present the findings narratively. Subgroup analysis and sensitivity analysis will be performed where appropriate.

Ethics And Dissemination: This scoping review aims to provide an overview of smartphone ophthalmoscopy in DR identification. It will present findings on the accuracy of smartphone ophthalmoscopy in detecting DR, identify gaps in the literature and provide recommendations for future research. This review does not require ethical approval as we will not collect primary data.
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http://dx.doi.org/10.1136/bmjopen-2018-028811DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6924876PMC
December 2019

Choroidal Thickness in Pre-eclampsia.

Curr Eye Res 2020 02 4;45(2):227. Epub 2019 Oct 4.

Department of Ophthalmology, National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore.

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http://dx.doi.org/10.1080/02713683.2019.1665185DOI Listing
February 2020

Long-Term Changes in Submacular Choroidal Thickness After Treatment for Neovascular Age-Related Macular Degeneration.

Curr Eye Res 2020 04 3;45(4):526. Epub 2020 Jan 3.

Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.

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http://dx.doi.org/10.1080/02713683.2019.1662054DOI Listing
April 2020

Effect of Fasting on Choroidal Thickness and Its Diurnal Variation.

Curr Eye Res 2019 11 25;44(11):1278. Epub 2019 Jun 25.

National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore.

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http://dx.doi.org/10.1080/02713683.2019.1634738DOI Listing
November 2019

Multicolor Fundus Imaging of Polypoidal Choroidal Vasculopathy.

Ophthalmol Retina 2019 05 18;3(5):400-409. Epub 2019 Jan 18.

National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore.

Purpose: Polypoidal choroidal vasculopathy (PCV) is a variant of neovascular age-related macular degeneration with distinct phenotypes, treatment, and visual prognosis. Multicolor imaging is a novel noninvasive imaging method that enables visualization of structures located at different layers of the retina and may be useful in detecting features of diseases. The features of PCV seen on multicolor imaging have not been studied. We aimed to describe the features of PCV detected using multicolor imaging and to compare these with standard color fundus photography (CFP).

Design: Hospital-based, cross-sectional study.

Participants: Fifty consecutive treatment-naive patients diagnosed with PCV seen in a tertiary referral center.

Methods: Multimodal imaging was performed using standardized protocols, and included CFP, multicolor imaging, fluorescein angiography, and indocyanine green angiography (ICGA). The CFP and ICGA images were independently graded by reading center-certified retinal specialists to confirm the diagnosis of PCV and identify lesion components. The features of the lesion components seen on multicolor images were compared with those detected using CFP and ICGA.

Main Outcome Measures: Frequency and features of lesions associated with PCV, specifically, polyps, branching vascular network (BVN), pigment epithelial detachments (PEDs), hemorrhages, and drusen.

Results: The mean age of the 50 participants was 67.9 years, and 60% were male. Polyps were most clearly seen on the infrared reflectance image and detected in 49 of 50 eyes (98%), appearing as dark gray oval lesions with distinct margins. On the multicolor composite images, polyps appeared as dark green oval lesions. The BVN appeared as mottled gray regions on infrared reflectance imaging and were seen less frequently compared with polyps (30/50 eyes, 60%). The margins of the BVN were less distinct compared with polyps. Other clinical features detected using multicolor imaging included PEDs (26%), subretinal hemorrhages (40%), and drusen (66%).

Conclusions: Multicolor imaging is able to detect polypoidal lesions in most patients with PCV. The appearance of PCV lesions on multicolor imaging differs from standard CFP, although the location and shape of lesions correlate well with features seen on CFP and ICGA. Multicolor imaging is a useful, noninvasive adjunct to detect features suggestive of PCV, which may prompt definitive investigations such as ICGA.
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http://dx.doi.org/10.1016/j.oret.2019.01.009DOI Listing
May 2019

Insights of Swept-Source Optical Coherence Tomographic Angiography on the Structures in Polypoidal Choroidal Vasculopathy.

JAMA Ophthalmol 2019 06;137(6):650-651

Fundus Image Reading Centre, National Healthcare Group Eye Institute, Singapore.

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http://dx.doi.org/10.1001/jamaophthalmol.2019.0412DOI Listing
June 2019

EVEREST study report 4: Fluorescein angiography features predictive of polypoidal choroidal vasculopathy.

Clin Exp Ophthalmol 2019 07 10;47(5):614-620. Epub 2019 Feb 10.

Fundus Image Reading Centre, National Healthcare Group Eye Institute, Singapore, Singapore.

Importance: It is important to identify features of polypoidal choroidal vasculopathy (PCV) that differentiate it from typical neovascular age-related macular degeneration (nAMD) on various imaging modalities, including fluorescein angiography (FA).

Background: PCV was thought to be indistinguishable from nAMD using FA alone. In real-world practice, indocyanine-green angiography may often be unavailable or contraindicated.

Design: Analysis of FA images from a prospective, multicentre study.

Participants: Study images of both PCV and nAMD patients from the EVEREST study.

Methods: FA features at baseline were independently graded by masked graders (fellowship-trained ophthalmologists) using standardized diagnostic algorithms.

Main Outcome Measures: Predictive indicators (sensitivity, specificity, positive and negative predictive values) for PCV.

Results: Of the 95 patients screened, 61 had PCV. Of the 34 screening failures, 15 were diagnosed as nAMD. Hyperfluorescent nodules on FA were observed in 80% of patients with PCV vs 20% with nAMD (P < 0.001). Blocked fluorescence on FA, which corresponded to the presence of subretinal haemorrhage, occurred more frequently among patients with PCV vs nAMD (61.7% vs 13.3%, P = 0.001). Similarly, the leakage characteristic of occult choroidal neovascularization occurred more frequently among patients with PCV vs nAMD (95.0% vs 73.3%, P = 0.026). The positive predictive value for PCV was 94.1% for hyperfluorescent nodules, 94.9% for blocked fluorescence, 83.8% for occult choroidal neovascularization and 82.0% for pigment epithelial detachment.

Conclusions And Relevance: This study demonstrated that certain FA features can be predictive of PCV and may be considered as an indication for retina specialists to perform indocyanine green angiography as confirmatory test.
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http://dx.doi.org/10.1111/ceo.13464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6767036PMC
July 2019

Corneal, Scleral, Choroidal, and Foveal Thickness in Patients with Rheumatoid Arthritis

Turk J Ophthalmol 2018 Dec;48(6):326-327

National Health Group Eye Institute, Tan Tock Seng Hospital, Singapore

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http://dx.doi.org/10.4274/tjo.36528DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6330666PMC
December 2018

The role of dilated fundus examination following cataract surgery.

J Cataract Refract Surg 2019 01;45(1):113

Singapore.

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http://dx.doi.org/10.1016/j.jcrs.2018.09.031DOI Listing
January 2019

Multicolour imaging for the detection of polypoidal choroidal vasculopathy and age-related macular degeneration.

Clin Exp Ophthalmol 2019 07 14;47(5):621-630. Epub 2019 Feb 14.

National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore, Singapore.

Importance: Multicolour is a new imaging technology and its sensitivity for detecting polypoidal choroidal vasculopathy (PCV) and age-related macular degeneration (AMD) has not been well described.

Background: To evaluate the accuracy of multicolour imaging compared to colour fundus photography (CFP) in differentiating AMD and PCV from normal eyes, and in detecting PCV.

Design: Prospective cohort study at a tertiary referral centre.

Participants: Fifty consecutive patients with PCV or AMD.

Methods: Standardized multimodal imaging, including CFP, multicolour imaging, and fluorescein and indocyanine green angiography, were graded by a Central Reading Center using standardized grading protocols.

Main Outcomes And Measures: Sensitivity, specificity, positive and negative predictive values (PPV and NPV).

Results: Of 100 eyes, 44 had PCV, 33 had AMD, and 23 were normal. Multicolour imaging had higher specificity (73.9% vs 52.2%) and NPV (94% vs 85.7%) compared to CFP for detecting all types of AMD. For the detection of PCV, multicolour had higher sensitivity (86.4% vs 59.1%) and NPV (89.3% vs 74.3%). Polypoidal lesions were detected in 39 of 44 eyes (88.6%) using multicolour imaging, while the branching vascular network (BVN) was detected in 16 of 44 eyes (36.4%). Using BVN as a parameter, infrared imaging specificity and PPV for detecting PCV were 96.6% and 88.9%, respectively.

Conclusions And Relevance: Multicolour imaging is superior to standard CFP in differentiating AMD and PCV from normal eyes, and in detecting features of PCV. Specific features seen on multicolour imaging can alert ophthalmologists to the likely presence of these diseases so that additional definitive investigations can be performed.
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http://dx.doi.org/10.1111/ceo.13462DOI Listing
July 2019

Sex-Dependent Choroidal Thickness Differences in Healthy Adults: A Study Based on Original and Synthesized Data.

Curr Eye Res 2019 02 29;44(2):236. Epub 2018 Oct 29.

b Department of Ophthalmology , Tan Tock Seng Hospital , Singapore.

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http://dx.doi.org/10.1080/02713683.2018.1532013DOI Listing
February 2019

Independent Factors of Choroidal Thickness.

Ocul Immunol Inflamm 2019 6;27(4):567-568. Epub 2018 Aug 6.

a Tan Tock Seng Hospital , National Healthcare Group Eye Institute , Singapore , Singapore.

We read with interest the article by Agarwal et al. reporting that mean choroidal thickness was significantly higher in HIV patients, especially those with HIV microangiopathy, compared to healthy controls matched for age, ethnicity, and gender. We would like to highlight two important factors which may affect choroidal thickness assessment, namely diurnal variation and myopia, which should be taken into consideration. It is important to know that mean choroidal thickness is likely to be higher among HIV patients, especially those with HIV microangiopathy, compared to healthy subjects. However, it is also important to note and account for other factors, such as timing of image acquisition and refractive errors of subjects, as these could potentially affect the study results.
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http://dx.doi.org/10.1080/09273948.2018.1499941DOI Listing
July 2019

Comment on 'Difference of uveal parameters between the acute primary angle closure eyes and the fellow eyes'.

Eye (Lond) 2018 12 31;32(12):1908-1916. Epub 2018 Jul 31.

Department of Ophthalmology, Tan Tock Seng Hospital, Singapore, Singapore.

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http://dx.doi.org/10.1038/s41433-018-0181-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6292878PMC
December 2018

Macular photostress and its impact on visual experience during cataract surgery.

J Cataract Refract Surg 2018 06 4;44(6):791. Epub 2018 Jul 4.

Singapore.

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http://dx.doi.org/10.1016/j.jcrs.2018.05.003DOI Listing
June 2018

Choroidal remodeling after photodynamic therapy for polypoidal choroidal vasculopathy.

Lasers Surg Med 2018 12 28;50(10):978-979. Epub 2018 Jun 28.

Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.

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http://dx.doi.org/10.1002/lsm.22998DOI Listing
December 2018

Letter to the Editor: Choroidal Thickness in Diabetic Macular Edema Compared to Normal Controls.

Curr Eye Res 2018 10 17;43(10):1302. Epub 2018 Jul 17.

c Singapore National Eye Centre, Singapore Health Services , Singapore.

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http://dx.doi.org/10.1080/02713683.2018.1493738DOI Listing
October 2018

Assessment of choroidal and retinal thickness in psychosis.

Psychiatry Res 2018 12 30;270:1172. Epub 2018 May 30.

Yong Loo Lin School of Medicine, National University of Singapore, Singapore.

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http://dx.doi.org/10.1016/j.psychres.2018.05.072DOI Listing
December 2018