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Articles by N Cheung
Total Records ( 3 ) for N Cheung
  V. S. E Jeganathan , N Cheung , W. T Tay , J. J Wang , P Mitchell and T. Y. Wong

Objective  To describe the prevalence and risk factors of retinopathy in an Asian population without diabetes.

Methods  We conducted a population-based, cross-sectional study of 3280 Malays aged 40 to 80 years residing in Singapore. Participants had retinal photographs taken, which were graded for retinopathy signs using the modified Airlie House Classification System. Risk factors were assessed from standardized interviews, clinical examinations, and laboratory investigations.

Results  Of participants without diabetes (n = 2500), 149 (6.0%; 95% confidence interval [CI], 5.0-6.9) had signs of retinopathy that represented minimal (5.8%) or mild (0.2%) retinopathy. After adjusting for multiple covariables, higher serum glucose levels (odds ratio [OR], 1.13; 95% CI, 1.00-1.28; per millimole per liter increase), higher systolic blood pressure (OR, 1.15; 95% CI, 1.06-1.25; per 10–mm Hg increase), higher body mass index (OR, 1.04; 95% CI, 1.00-1.07 per point increase), and a history of heart attack (OR, 2.68; 95% CI, 1.48-4.83) were significantly associated with the presence of retinopathy lesions in persons without diabetes.

Conclusions  Similar to studies in white individuals, signs of retinopathy are common in Asian persons without diabetes. Early signs of retinopathy in persons without diabetes are related to metabolic and vascular risk factors and may indicate intermediate pathologic changes along the pathway to cardiovascular disease.

  G. J Ben Simon , N Cheung and A. A. McNab

Objective  To report the incidence and risk factors associated with delayed epistaxis (2-8 days after the procedure) after external dacryocystorhinostomy (DCR).

Design  We identified and analyzed all cases of patients who underwent external DCR procedures at 2 institutions from January 1999 through December 2005. Cases of delayed epistaxis and their final surgical outcome were compared with those without it.

Setting  All patients who underwent surgery and were examined at 2 public hospitals in Melbourne, Australia.

Patients  A total of 374 patients who underwent 437 DCRs.

Interventions  Medical treatment, hospitalization, and endonasal examination with cautery.

Main Outcome Measures  Rate of delayed epistaxis and current and past use of antiplatelet medications.

Results  Of the 374 patients (mean [SD] age, 62 [18] years; 280 [75%] were women) who underwent 437 external DCRs, 15 (3.4%) had an episode of delayed epistaxis. They were generally older and more likely to have a history of active dacryocystitis compared with those who did not develop delayed epistaxis. Preoperative use of aspirin, nonsteroidal anti-inflammatory drugs, or warfarin sodium was not associated with delayed epistaxis or poorer surgical outcome if these anticoagulants were discontinued preoperatively as instructed. None of the 15 patients with delayed epistaxis had continued ingesting anticoagulants before undergoing DCR. Patients who developed epistaxis (80%) had a significantly lower rate of satisfactory surgical outcome than those who did not (90%) (P = .02).

Conclusion  The risk of delayed epistaxis should be similar for patients taking or not taking anticoagulant agents if their use is stopped within a defined period of time before DCR.

  N Cheung , T Mosley , A Islam , R Kawasaki , A. R Sharrett , R Klein , L. H Coker , D. S Knopman , D. K Shibata , D Catellier and T. Y. Wong

Silent brain infarct and white matter lesions are common radiological findings associated with the risk of clinical stroke and dementia; however, our understanding of their underlying pathophysiology and risk factors remains limited. This study aimed to determine whether assessment of retinal microvascular abnormalities could provide prognostic information regarding the risk of brain infarct and white matter lesions on magnetic resonance imaging. This study is based on a subset of 810 middle-aged persons without clinical stroke or baseline magnetic resonance imaging infarct enrolled in the Atherosclerosis Risk in Communities Brain Magnetic Resonance Imaging Study, a prospective, population-based study. Participants had a baseline magnetic resonance imaging brain examination and retinal photography in 1993–1995, and returned for a repeat magnetic resonance imaging examination in 2004–2006. Magnetic resonance images were graded for presence of any cerebral infarct, infarct with lacunar characteristics and white matter lesions according to standardized protocols. Retinal photographs were graded for presence of retinopathy lesions and retinal arteriolar abnormalities following a standardized protocol. Over a median follow-up of 10.5 years, 164 (20.2%) participants developed cerebral infarct, 131 (16.2%) developed lacunar infarct, 182 (24.2%) developed new white matter lesions and 49 (6.1%) had evidence of white matter lesion progression. After adjusting for age, gender, race, cardiovascular risk factors and carotid intima-media thickness, retinopathy was associated with incident cerebral infarct (odds ratio 2.82; 95% confidence interval 1.42–5.60) and lacunar infarct (odds ratio 3.19; 95% confidence interval: 1.56–6.50). Retinal arteriovenous nicking was associated with incident cerebral infarct (odds ratio 2.82; 95% confidence interval: 1.66–4.76), lacunar infarct (odds ratio 2.48; 95% confidence interval: 1.39–4.40) and white matter lesion incidence (odds ratio 2.12; 95% confidence interval: 1.18–3.81) and progression (odds ratio 2.22; 95% confidence interval: 1.00–5.88). In conclusion, retinal microvascular abnormalities are associated with emergence of subclinical magnetic resonance imaging brain infarcts and white matter lesions, independent of shared risk factors. Retinal vascular imaging may offer a non-invasive tool to investigate the pathogenesis and natural history of cerebral small-vessel disease.

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