Time filter

Source Type

Zhongshan, China

How A.C.,Singapore Eye Research Institute | Baskaran M.,Singapore Eye Research Institute | Kumar R.S.,Singapore Eye Research Institute | He M.,Zhongshan Ophthalmic Center | And 8 more authors.

Purpose: Novel anterior segment optical coherence tomography (ASOCT) parameters associated with angle closure include anterior chamber area (ACA), anterior chamber volume (ACV), anterior chamber width (ACW), lens vault (LV), iris thickness (IT), iris area (I-area), and iris curvature (I-curv). We aimed to investigate changes in these parameters after laser peripheral iridotomy (LPI) in a cohort of primary angle-closure suspects (PACS). Design: Prospective observational study. Participants and Controls: A total of 176 PACS aged <50 years who underwent LPI in 1 eye. Methods: We analyzed ASOCT images (Visante, Carl Zeiss Meditec, Dublin, CA) from all subjects using customized software before and 1 week after LPI. Multivariate linear regression analysis was performed for predictors of percentage change in mean angle opening distance (AOD750). Main Outcome Measures: Change in ASOCT parameters after LPI. Results: The mean age of participants was 63±7.3 years. The majority of subjects were Chinese (95.5%) and women (76.7%). Mean angle width (modified Shaffer grade) changed from 0.68±0.54 at baseline to 1.76±0.69 after LPI (P<0.001) with a corresponding increase in mean AOD500 (0.12 vs. 0.19 mm, P<0.001), trabecular iris surface area (TISA500, 0.06 vs. 0.08 mm 2, P<0.001), and angle recess area (ARA, 0.13 vs. 0.17 mm 2, P<0.001). Mean ACA (15.0 vs. 16.0 mm 2, P<0.001) and ACV (91.6 vs. 103.0 mm 3, P<0.001) increased significantly after LPI, but there was no change in ACW, anterior chamber depth (ACD), or LV. Mean I-curv was reduced (0.375 vs. 0.18 mm, P<0.001) after LPI, but there was no significant change in IT or I-area. After multivariate analysis, mean LV (β = 0.286, P = 0.001), mean IT at 2000 μm (IT2000, β = 0.172, P = 0.034), and intraocular pressure (β = 0.159, P = 0.042) at baseline were found to be associated with ΔAOD750. Conclusions: This study confirms that LPI results in a significant increase in the angle width in PACS. The ACA and ACV increased after LPI, but there was no change in ACD, ACW, LV, IT, or I-area. The increase in ACA/ACV was mainly due to decreased I-curv after LPI. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. © 2012 American Academy of Ophthalmology. Source

Tan X.,Nanjing Medical University | Tan X.,Zhongshan Ophthalmic Center | Tan X.,Jiangsu Institute of Nuclear Medicine | Tan X.,University of Sydney
Eye (London, England)

PURPOSE: To determine the levels of Th17-associated cytokines, particularly interleukin (IL)-17 and IL-22 in tears of patients with dry eye syndrome.METHODS: Tear samples were collected from 20 healthy volunteers, 20 dry eye (DE) patients with non-Sjögren's syndrome (NSSDE) and 20 DE patients with Sjögren's syndrome (SSDE). Symptom questionnaire was self-administered and multiple dry eye disease (DED)-related clinical tests were performed. The levels of IL-17 and IL-22 in tears were measured by enzyme-linked immunosorbent assay.RESULTS: The levels of IL-17 and IL-22 were significantly increased in tears of DE patients compared with those of controls and also higher in SSDE patients compared with those of NSSDE patients (P<0.05). Moreover, the levels of IL-17 and IL-22 were positively correlated with questionnaire score and keratopathy score but negatively correlated with tear film break-up time and Schirmer I test in both NSSDE and SSDE patients (P<0.05).CONCLUSIONS: The levels of IL-17 and IL-22 in tears were significantly increased in DE patients, which were associated with the disease severity. Therefore, Th17 cell-associated cytokines, particularly IL-17 and IL-22, may have important roles in the immunopathogenesis of the DED. Source

Yuen L.H.,Singapore National Eye Center | He M.,Zhongshan Ophthalmic Center | Aung T.,Singapore National Eye Center | Htoon H.M.,Singapore Eye Research Institute | And 3 more authors.
Investigative Ophthalmology and Visual Science

Purpose. To investigate the normative data of corneal and anterior segment biometric parameters and their associations in Chinese adults, for use in preoperative assessment for corneal and anterior segment surgery. Methods. This cross-sectional, population-based study included 750 subjects aged ≥50 years. The subjects underwent an ophthalmic examination including imaging with anterior segment optical coherence tomography (AS-OCT). Dimensions were subsequently measured with the Zhongshan Assessment Program (ZAP). Also measured was posterior corneal arc length (PCAL), a novel parameter defined as the arc distance between scleral spurs on the posterior border of the cornea. Correlations with age, sex, height, weight, body mass index (BMI), refractive sphere and cylinder, and intraocular pressure were also measured. Results. The subjects' mean age was 63.3 ± 7.9 years and 349 (46.5%) were men. Corneal parameters (mean ± SD) included PCAL (12.924 ± 0.544 mm), anterior chamber depth (ACD; 2.684 ± 0.309 mm), central corneal thickness (562.39 ± 31.85 fjim), anterior chamber curvature (7.35 ± 0.37 mm), and posterior corneal curvature (6.65 ± 0.34 mm). A moderate correlation was observed between PCAL and ACD (R = 0.55, P < 0.001) and a poor correlation between PCAL and age, height, weight, and BMI. Multivariate analysis showed a significant association between PCAL and ACD, ACC, PCC, and cylinder (P < 0.05).Conclusions. In this Chinese population, PCAL was found to correlate moderately with ACD. The data may be useful for corneal and anterior segment procedures such as Descemet's stripping automated endothelial keratoplasty (DSAEK). © Association for Research in Vision and Ophthalmology. Source

Narayanaswamy A.,Singapore Eye Research Institute | Sakata L.M.,Federal University of Parana | He M.-G.,Zhongshan Ophthalmic Center | Friedman D.S.,Wilmer Eye Institute | And 6 more authors.
Archives of Ophthalmology

Objective: To assess the diagnostic performance of angle measurements from anterior segment optical coherence tomography (AS-OCT) images for identifying eyes with narrow angles. Methods: We conducted a community-based cross-sectional study of individuals 50 years or older who had phakic eyes and who underwent AS-OCT imaging in the dark by a single operator and gonioscopy by an ophthalmologist masked to AS-OCT findings. An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for at least 180° on gonioscopy. Horizontal AS-OCT images were analyzed for the following measurements using customized software: angle opening distance (AOD) at 250, 500, and 750 μm from the scleral spur; trabecular-iris space area (TISA) at 500 and 750 μm; and angle recess area (ARA) at 750 μm. Areas under the receiver operating characteristic curves (AUCs) were generated for AOD, TISA, and ARA to assess the performance of these measurements in detecting eyes with narrow angles. Results: Of 2047 individuals examined, 582 were excluded mostly because of poor image quality or inability to locate the scleral spur. Of the remaining 1465 participants, 315 (21.5%) had narrow angles on gonioscopy. Mean (SD) age was 62.7 (7.7) years, 54.1% were women, and 90.0% were Chinese. The AUCs were highest for AOD750 in the nasal (0.90 [95% confidence interval, 0.89-0.92]) and temporal (0.91 [0.90-0.93]) quadrants. Conclusions: The AOD750 is the most useful angle measurement for identifying individuals with gonioscopic narrow angles in gradable AS-OCT images. Poor definition of the scleral spur precludes quantitative analysis in approximately 25% of AS-OCT images. ©2010 American Medical Association. All rights reserved. Source

Chen Y.,Ophthalmic Research Institute | Lan W.,Ophthalmic Research Institute | Lan W.,Zhongshan Ophthalmic Center | Schaeffel F.,Ophthalmic Research Institute
Vision Research

When the eye is covered with a filter that transmits light below 480. nm and a blue field is observed on a computer screen that is modulated in brightness at about 1. Hz, the fovea is perceived as small irregular dark spot. It was proposed that the "foveal blue scotoma" results from the lack of S-cones in the foveal center. The foveal blue scotoma is highly variable among subjects. Possible factors responsible for the variability include differences in S-cone distribution, in foveal shape, and in macular pigment distribution. Nine young adult subjects were instructed to draw their foveal blue scotomas on a clear foil that was attached in front of the computer screen. The geometry of their foveal pit was measured in OCT images in two dimensions. Macular pigment distribution was measured in fundus camera images. Finally, blue scotomas were compared with Maxwell's spot which was visualized with a dichroic filter and is commonly assumed to reflect the macular pigment distribution. The diameters of the foveal blue scotomas varied from 15.8 to 76.4. arcmin in the right eyes and 15.5 to 84.7. arcmin in the left and were highly correlated in both eyes. It was found that the steeper the foveal slopes and the narrower the foveal pit, the larger the foveal blue scotoma. There was no correlation between foveal blue scotoma and macular pigment distribution or Maxwell's spot. The results are therefore in line with the assumption that the foveal blue scotoma is a consequence of the lack of S-cones in the foveal center. Unlike the foveal blue scotoma, Maxwell's spot is based on macular pigment as previously proposed. © 2014 Elsevier B.V. Source

Discover hidden collaborations