Clinical Instructor, Ophthalmology
Fellowship: Stanford University Ophtalmology Fellowships (2020) CA
Board Certification: Ophthalmology, American Board of Ophthalmology (2019)
Residency: Wilmer Eye Institute Ophthalmology Residency (2018) MD
Internship: Greater Baltimore Medical Center Internal Medicine Residency (2015) MD
Medical Education: National Taiwan University College of Medicine (2008) Taiwan
PhD, Bloomberg School of Public Health, Johns Hopkins University, Epidemiology (2013)
MPH, Bloomberg School of Public Health, Johns Hopkins University (2009)
MD, National Taiwan University (2008)
- A 3D Deep Learning System for Detecting Referable Glaucoma Using Full OCT Macular Cube Scans TRANSLATIONAL VISION SCIENCE & TECHNOLOGY 2020; 9 (2)
Efficacy of Laser Peripheral Iridotomy for the Prevention of Angle Closure: A Randomized Controlled Trial
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
View details for Web of Science ID 000488628104164
Macular sensitivity endpoints in geographic atrophy secondary to age-related macular degeneration - exploratory analysis of two parallel randomized phase 3 trials
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
View details for Web of Science ID 000488628105157
The incidence of acute angle-closure attack in primary angle closure suspect after pharmacologic mydriasis: A randomized controlled trial
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
View details for Web of Science ID 000488628106345
Laser peripheral iridotomy for the prevention of angle closure: a single-centre, randomised controlled trial.
Lancet (London, England)
2019; 393 (10181): 1609–18
Primary angle-closure glaucoma affects 20 million people worldwide. People classified as primary angle closure suspects have a higher but poorly quantified risk of developing glaucoma. We aimed to assess efficacy and safety of laser peripheral iridotomy prophylaxis against primary angle-closure glaucoma in Chinese people classified as primary angle closure suspects.In this randomised controlled trial, bilateral primary angle closure suspects aged 50-70 years were enrolled at the Zhongshan Ophthalmic Center, a tertiary specialised hospital in Guangzhou, China. Eligible patients received laser peripheral iridotomy in one randomly selected eye, with the other remaining untreated. The primary outcome was incident primary angle closure disease as a composite endpoint of elevation of intraocular pressure, peripheral anterior synechiae, or acute angle-closure during 72 months of follow-up in an intention-to-treat analysis between treated eyes and contralateral controls. This trial is registered with the ISRCTN registry, number ISRCTN45213099.Of 11 991 screened individuals, 889 individuals were randomly assigned from June 19, 2008 (889 treated and 889 untreated eyes). Incidence of the primary outcome was 4·19 per 1000 eye-years in treated eyes compared with 7·97 per 1000 eye-years in untreated eyes (hazard ratio 0·53; 95% CI 0·30-0·92; p=0·024). A primary outcome event occurred in 19 treated eyes and 36 untreated eyes with a statistically significant difference using pair-wise analysis (p=0·0041). No serious adverse events were observed during follow-up.Incidence of angle-closure disease was very low among individuals classified as primary angle closure suspects identified through community-based screening. Laser peripheral iridotomy had a modest, albeit significant, prophylactic effect. In view of the low incidence rate of outcomes that have no immediate threat to vision, the benefit of prophylactic laser peripheral iridotomy is limited; therefore, widespread prophylactic laser peripheral iridotomy for primary angle-closure suspects is not recommended.Fight for Sight, the Sun Yat-Sen University 5010 Project Fund, Moorfields Eye Charity, and the National Natural Science Foundation of China.
View details for DOI 10.1016/S0140-6736(18)32607-2
View details for PubMedID 30878226
- Central Scotoma After Liver Transplant. JAMA ophthalmology 2019; 137 (2): 214–15
The Relationship Between Quantitative Pupillometry and Estimated Ganglion Cell Counts in Patients With Glaucoma.
Journal of glaucoma
2019; 28 (3): 238–42
To assess the relationship between pupillary light reflex and estimated retinal ganglion cell (RGC) counts in patients with glaucoma.We recorded and analyzed pupil responses using an automated binocular pupillometer in 148 patients with glaucoma (mean age 67±11, 49% female) and 71 controls (age 60±9.6, 69% female) as part of a prospective clinical study. The amplitude of pupil constriction was calculated as the percentage change in pupil diameter between constriction onset and peak constriction in response to controlled stimuli. The magnitude of a relative afferent pupillary defect (RAPD) was defined as the log of the ratio of the amplitude between 2 eyes multiplied by 10. RGC counts were estimated using empirical formulas that combine estimates from both functional (eccentricity and sensitivity measured by standard automated perimetry) and structural (retinal nerve fiber layer thickness) tests. For analyses performed at the level of individual eyes, we used multilevel modeling to account for between-eye correlations within individuals.Eyes with higher estimated RGC counts had a larger pupil response amplitude (z-score=8.24, P<0.001), shorter latency (z=-3.17, P=0.002), faster constriction velocity (z=6.64, P<0.001), shorter time to maximum constriction (z=-1.96, P=0.049), and longer time to maximum dilation (z=6.66, P<0.001). For every 0.3 log unit difference in RAPD score, there was an average decrease in estimated RGC count of 37,817 (P<0.001).There is a statistically significant association between estimated RGC count and pupillary response to stimuli. Quantitative pupillography may be useful in diagnosis and monitoring of optic neuropathies.
View details for DOI 10.1097/IJG.0000000000001183
View details for PubMedID 30624390
Darkroom prone provocative testing in primary angle closure suspects and those with open angles.
The British journal of ophthalmology
To describe the results of darkroom prone provocative testing (DRPPT) in primary angle closure suspects (PACS) and to compare the findings to controls with open angles.889 subjects with PACS in the Zhongshan Angle Closure Prevention Trial (a randomised controlled trial to compare prophylactic laser iridotomy to no treatment in PACS) and 89 with open angles in the 5-year follow-up of Liwan Eye Study were placed in a darkroom face down for 15 min. Intraocular pressure (IOP) was measured immediately before and after DRPPT.PACS participants were of similar age than controls (59.3 vs 60.5), more often female (82.9% vs 58.4%) and had lower IOP (14.3 vs 15.2 mm Hg). The average IOP increases after DRPPT was 4.3±3 mm Hg in PACS and 5.2±2.8 in controls (p<0.05). 20.5% of controls and 13.9 % of those with PACS developed an IOP spike ≥8 mm Hg after DRPPT (p<0.05). Among PACS, 15.8 % of those with all four quadrants closed had an IOP elevation of ≥ 8 mm Hg as opposed to 10.0%-12.4 % with two or three closed quadrants (p<0.05). DRPPT failed to predict who would reach a clinical trial endpoint over 6-year follow-up of those with PACS.A modified DRPPT failed to separate PACS from those with open angle. Although the test resulted in greater IOP elevation among those PACS participants with all four quadrants closed than in those with two or three closed quadrants, it did not offer any insight into the risk of developing acute or chronic angle closure disease over 6-year follow-up.
View details for DOI 10.1136/bjophthalmol-2018-313362
View details for PubMedID 30819689
Prevalence of eye disease and reading difficulty in an inner city elementary school population - Preliminary results from the Baltimore Reading and Eye Disease Study (BREDS)
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2016
View details for Web of Science ID 000394174003361
The relationship between quantitative pupillometry and estimated ganglion cell counts in patients with glaucoma
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2016
View details for Web of Science ID 000394210202182
Results From a Modified Bleb Needling Procedure With Continuous Infusion Performed in the Operating Room.
Journal of glaucoma
2016; 25 (9): 720–26
Needling of a scarred trabeculectomy bleb is often performed in the office using a slit-lamp microscope as an alternative to additional surgery to lower intraocular pressure (IOP). However, the success rate in an office setting is highly variable, with reported success rates as low as 13%. We report a retrospective assessment of an intraoperative needling technique for reviving failed blebs.A retrospective chart review.Patients undergoing the intraoperative modified bleb revision technique in the setting of a failed trabeculectomy due to scarring at the Wilmer Eye Institute, Johns Hopkins Hospital between August 16, 2010 and August 29, 2012.Patients with uncontrolled IOP were operated on using a modified bleb needling technique. In this technique, a 25-G infusion cannula is placed in the anterior chamber and fibrotic adhesions within the bleb are lysed with a 25-G needle. The continuous infusion of balanced salt solution from the anterior chamber causes bleb elevation, which helps to guide the endpoint of lysis for the procedure. A subconjunctival injection of 5-fluorouracil is given at the conclusion of each case.IOP reduction and number of glaucoma medications at postoperative day 1, week 1, month 1, month 3, month 6, and month 12.A total of 33 eyes of 30 patients were included. At the visit before the procedure, the mean (±SD) IOP was 22.1±9.2 (range, 11 to 58) and subjects were using an average of 2.3±1.4 (range, 0 to 4) glaucoma medications. The mean IOP reduction was 8.7 mm Hg [95% confidence interval (CI), 5.6-11.8] at postoperative day 1, 8.1 mm Hg (95% CI, 4.0-12.3) at week 1, 8.9 mm Hg (95% CI, 5.3-12.5) at month 1, 8.1 mm Hg (95% CI, 4.2-12.0) at month 3, 8.2 mm Hg (95% CI, 3.9-12.5) at month 6, and 6.2 mm Hg (95% CI, 3.6-8.7) at month 12. IOP was reduced about 30% to 40% compared with baseline at each time point (P<0.05). The average reduction in medications used was 1.7 at day 1, 1.0 at month 1, 1.2 at month 3, 1.5 at month 6, and 0.5 at month 12. Seven patients underwent repeat needling. Overall, 64% of subjects maintained IOP at or below their target after 12 months.A modified bleb needling procedure performed in the operating room can successfully lower IOP in the setting of a previous trabeculectomy in over 60% of subjects a year after the procedure.
View details for DOI 10.1097/IJG.0000000000000511
View details for PubMedID 27552502
The Association between Near Work Activities and Myopia in Children-A Systematic Review and Meta-Analysis.
2015; 10 (10): e0140419
Myopia has a multifactorial etiology, although environmental factors are predominant in determining its current patterns. Currently, associations between near work activities and myopia have not been consistently observed. Therefore, we performed a systematic review to quantify the effect of near work activities on myopia in children. Relevant articles published between 1989 and 2014 were identified in MEDLINE, Embase, and the Cochrane Library, and the citation lists were reviewed. Twelve cohort studies and 15 cross-sectional studies were included (25,025 children aged between 6 and 18 years). The I2 statistic was used to assess heterogeneity. Study-level data were pooled using a random-effects model or a fixed-effects model (when less than 5 studies were included). We found that more time spent on near work activities was associated with higher odds of myopia (odds ratio [OR] = 1.14; 95% confidence interval [CI] = 1.08-1.20) and that the odds of myopia increased by 2% (OR:1.02; 95% CI = 1.01-1.03) for every one diopter-hour (hr) more of near work per week. Therefore, the development of a strategy to reduce the impact of near work on myopia would be important for preventing myopia in children.
View details for DOI 10.1371/journal.pone.0140419
View details for PubMedID 26485393
View details for PubMedCentralID PMC4618477
Longitudinal changes of angle configuration in primary angle-closure suspects: the Zhongshan Angle-Closure Prevention Trial.
2014; 121 (9): 1699–1705
To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes.Longitudinal cohort study.Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial.Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI.Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images.No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8-1.6) in treated eyes and 1.6°/year (95% CI, 1.3-2.0) in untreated eyes (P<0.001).Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period.
View details for DOI 10.1016/j.ophtha.2014.03.039
View details for PubMedID 24835757
View details for PubMedCentralID PMC4624262
Assessment of a rapid method to determine approximate visual acuity in large surveys and other such settings.
American journal of ophthalmology
2014; 157 (6): 1315–21.e1
To evaluate the efficacy of an iPod application developed to rapidly measure approximate visual acuity (VA).Prospective, cross-sectional study.One hundred four subjects (104 eyes) with a wide range of VA underwent both Early Treatment Diabetic Retinopathy Study (ETDRS) VA testing and iPod application testing. The application presented 4 randomized ETDRS letters at the Snellen equivalent of 20/40 and 20/200 each. In separate analyses, sensitivity and specificity of the iPod test were determined using the ETDRS VA testing results as the gold standard and defining "failure" to see as identifying 1, 2, 3, or all 4 letters incorrectly out of 4 trials. The minimum number of iPod trials necessary to maintain high accuracy was determined by defining a "failure" as getting the first, first 2, first 3, or all trial letters incorrect. In 13 subjects, the time necessary to perform the testing was determined.Forty-six subjects had an ETDRS Snellen equivalent VA ≥20/40; 45 had a VA <20/40 and ≥20/200; and 13 had a VA <20/200. The mean ± SD testing time for the 3 groups was 43 ± 13, 60 ± 15, and 72 ± 25 seconds, respectively. The highest sensitivity and specificity combination was observed when a "failure" was defined as getting all letters incorrect for both the 20/40 (sensitivity = 98.3%/specificity = 93.5%) and 20/200 (sensitivity/specificity both 92.3%) cutoffs.An iPod application requiring about a 1-minute testing time provides an objective, portable, rapid, and low-cost method to determine approximate VA, allowing VA testing to be performed efficiently in large surveys and other settings where approximate VA should be measured.
View details for DOI 10.1016/j.ajo.2014.02.031
View details for PubMedID 24548874
Electronic monitoring to assess adherence with once-daily glaucoma medications and risk factors for nonadherence: the automated dosing reminder study.
2014; 132 (7): 838–44
Adherence with topical glaucoma medications is low in some patients. To identify these patients, we need more information on risk factors for nonadherence.To assess adherence with once-daily glaucoma medication.Prospective cohort study involving patients who were recruited from a university-based glaucoma clinic and treated with once-daily prostaglandin eyedrops. Baseline characteristics were recorded, and each patient was provided a medication bottle to hold his or her eyedrop bottle throughout the study. An electronic cap recorded each time the larger bottle holding the eyedrops was opened. Participants were administered standardized tests of depression and mental status and answered questions about their health and their attitudes toward medication adherence. They used the electronic monitors for 3 months, during which their adherence with medications was assessed.Adherence with daily glaucoma medication and factors associated with poor adherence.Of the 491 participants enrolled, 407 (82.9%) successfully completed the 3-month adherence assessment. Of this group, 337 (82.8%) took their medication correctly on at least 75% of days and were deemed adherent. Compared with this adherent group, the 70 participants (17.2%) who were nonadherent were slightly younger, were more likely to be of African descent, took medications for a shorter time, had a lower level of educational attainment, and had worse scores on mental status and depression scales (P < .05 for all). Nonadherent participants were less likely to be able to name their glaucoma medications, reported a lower estimate of adherence, and were more likely to admit some missed doses over the past 2 weeks or in general (P < .05 for all). Those who were nonadherent were also less likely to agree that remembering their eyedrops is easy, more likely to strongly agree with the statement that eyedrops can cause problems, and less likely to agree that they followed physicians' orders.Electronic monitoring of patient adherence documented that a sizable number of patients with glaucoma do not take their medications as prescribed. Factors were identified that may prove useful in targeting those nonadherent patients for interventions.
View details for DOI 10.1001/jamaophthalmol.2014.856
View details for PubMedID 24830878
Automated telecommunication-based reminders and adherence with once-daily glaucoma medication dosing: the automated dosing reminder study.
2014; 132 (7): 845–50
Topical glaucoma medications lower intraocular pressure and alter the course of the disease. Because adherence with glaucoma medications is a known problem, interventions are needed to help those patients who do not take their medications as prescribed.To assess the ability of an automated telecommunication-based intervention to improve adherence with glaucoma medications.We performed a prospective cohort study of medication adherence, followed by a randomized intervention for those found to be nonadherent, of individuals recruited from a university-based glaucoma subspecialty clinic. A total of 491 participants were enrolled in the initial assessment of adherence. Of those, 70 were nonadherent with their medications after 3 months of electronic monitoring and randomized to intervention and control groups.A personal health record was used to store the list of patient medications and reminder preferences. On the basis of those data, participants randomized to the intervention received daily messages, either text or voice, reminding them to take their medication. Participants randomized to the control group received usual care.Difference in adherence before and after initiation of the intervention.Using an intent-to-treat analysis, we found that the median adherence rate in the 38 participants randomized to the intervention increased from 53% to 64% (P < .05). There was no statistical change in 32 participants in the control group. To assess the real efficacy of the intervention, the same comparison was performed for the participants who successfully completed the study after randomization. Analyzed this way, the adherence rate in the 20 participants in the intervention group increased from 54% to 73% (P < .05), whereas there was again no statistical change in the 19 participants in the control group. Eighty-four percent of the participants who received reminders agreed they were helpful and would continue using them outside the study.Automated telecommunication-based reminders linked to data in a personal health record improved adherence with once-daily glaucoma medications. This is an effective method to improve adherence that could realistically be implemented in ophthalmology practices with a minimum amount of effort on the part of the practice or the patient.
View details for DOI 10.1001/jamaophthalmol.2014.857
View details for PubMedID 24831037
Symmetry of the Pupillary Light Reflex and its Relationship to Retinal Nerve Fiber Layer Thickness and Visual Field Defect in Subjects With and Without Glaucoma
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2013
View details for Web of Science ID 000436232705153
Development and validation of an associative model for the detection of glaucoma using pupillography.
American journal of ophthalmology
2013; 156 (6): 1285–96.e2
To develop and validate an associative model using pupillography that best discriminates those with and without glaucoma.A prospective case-control study.We enrolled 148 patients with glaucoma (mean age 67 ± 11) and 71 controls (mean age 60 ± 10) in a clinical setting. This prototype pupillometer is designed to record and analyze pupillary responses at multiple, controlled stimulus intensities while using varied stimulus patterns and colors. We evaluated three approaches: (1) comparing the responses between the two eyes; (2) comparing responses to stimuli between the superonasal and inferonasal fields within each eye; and (3) calculating the absolute pupil response of each individual eye. Associative models were developed using stepwise regression or forward selection with Akaike information criterion and validated by fivefold cross-validation. We assessed the associative model using sensitivity, specificity and the area-under-the-receiver operating characteristic curve.Persons with glaucoma had more asymmetric pupil responses in the two eyes (P < 0.001); between superonasal and inferonasal visual field within the same eye (P = 0.014); and smaller amplitudes, slower velocities and longer latencies of pupil responses compared to controls (all P < 0.001). A model including age and these three components resulted in an area-under-the-receiver operating characteristic curve of 0.87 (95% CI 0.83 to 0.92) with 80% sensitivity and specificity in detecting glaucoma. This result remained robust after cross-validation.Using pupillography, we were able to discriminate among persons with glaucoma and those with normal eye examinations. With refinement, pupil testing may provide a simple approach for glaucoma screening.
View details for DOI 10.1016/j.ajo.2013.07.026
View details for PubMedID 24011523
View details for PubMedCentralID PMC3880829
Development and validation of a predictive model for nonadherence with once-daily glaucoma medications.
2013; 120 (7): 1396–1402
To develop and validate a predictive model to estimate the probability of being nonadherent to topical glaucoma medications.Prospective cohort study.Patients being treated with once-daily prostaglandin eye drops.A predictive model for nonadherence was developed from the Travatan Dosing Aid (TDA) study (n = 196) using stepwise logistic regression. The performance of the TDA-derived model was assessed using a separate cohort of subjects from the Automated Dosing Reminder Study (ADRS; n = 407). The assessment was based on regression coefficients, discrimination, and calibration. We also developed a scoring system from the TDA-derived model to simplify the estimation of risk for clinical use.Usage of drops was monitored electronically for 3 months in both studies. Adherence was calculated as the percentage of days on which a dose was taken within 4 hours of the average dosing time for that patient. Nonadherence was defined as taking ≤ 75% prescribed doses within a window starting 2 weeks after the baseline visit until 2 weeks before the follow-up visit.Six factors, including younger age, black race, worse general health status, shorter duration of glaucoma medication therapy, lower self-reported adherence, and admitting to not following doctors' orders, were associated with being nonadherent and were included in the predictive model. The coefficients for the TDA-derived and the ADRS-derived predictive models were similar. The risk scoring system developed from the TDA study had good discrimination (area under the receiver operating characteristic curve of 0.80) and calibration (Hosmer-Lemeshow goodness-of-fit test, P = 0.102) when applied to the ADRS population.The TDA-derived predictive model for nonadherence performed well in an independent population. A risk scoring system was developed using demographic data and patient responses to 4 questions to provide an estimate of the probability of being nonadherent.
View details for DOI 10.1016/j.ophtha.2013.01.002
View details for PubMedID 23541760
View details for PubMedCentralID PMC4016983
Accuracy of pupil assessment for the detection of glaucoma: a systematic review and meta-analysis.
2013; 120 (11): 2217–25
To assess the accuracy of using pupillary light reflex (PLR) in detecting glaucoma.Glaucoma is a specific disease of the optic nerve and is often more severe in 1 eye. When large enough, this asymmetry in disease severity can cause a relative afferent pupillary defect (RAPD). Better detection of RAPDs may be one way to identify persons with glaucoma.We searched Medline and Embase through June 2012 and searched bibliographies for relevant studies for additional references. Two authors independently reviewed all articles and selected studies that assessed PLRs in patients with glaucoma. We analyzed data using mixed-effect bivariate summary receiver operating characteristic meta-analysis models.A total of 30 studies were included in this review. An RAPD was observed in 9% to 82% of patients with glaucoma. Eleven studies with a total of 7271 participants were included in the analysis, and the pooled estimate corresponded to a sensitivity of 0.63 (95% confidence interval [CI], 0.43-0.80) and a specificity of 0.93 (95% CI, 0.85-0.97). After excluding 2 studies that used the swinging flashlight test, the sensitivity increased to 0.74 (95% CI, 0.59-0.85) with a specificity of 0.85 (95% CI, 0.77-0.90). Study designs and different pupil measurement techniques explained part of the heterogeneity between studies.Patients with glaucoma frequently have an abnormal PLR and comparing the responses between the 2 eyes can in part distinguish between those with glaucoma and those without the disease. Newer instruments and analytic approaches to assess pupil function may improve the performance of pupil screening.
View details for DOI 10.1016/j.ophtha.2013.04.012
View details for PubMedID 23809274
View details for PubMedCentralID PMC3818414
Symmetry of the pupillary light reflex and its relationship to retinal nerve fiber layer thickness and visual field defect.
Investigative ophthalmology & visual science
2013; 54 (8): 5596–5601
To assess the relationship between the pupillary light reflex (PLR) and visual field (VF) mean deviation (MD) and retinal nerve fiber layer (RNFL) thickness.A total of 148 patients with glaucoma (mean age 67 ± 11, 49% female) and 71 controls (mean age 60 ± 10, 69% female) were included in this study. Using a pupillometer, we recorded and analyzed pupillary responses at varied stimulus patterns (full field, superonasal and inferonasal quadrant arcs). We compared the responses between the two eyes, compared responses to stimuli in the superonasal and inferonasal fields within each eye, and calculated the absolute PLR value of each individual eye. We assessed the relationship among PLR, MD, and RNFL thickness using the Pearson correlation coefficient. For analyses performed at the level of individual eyes, we used multilevel modeling to account for between-eye correlations within individuals.For every 0.3 log unit difference in between-eye asymmetry of PLR, there was an average 2.6-dB difference in visual field MD (correlation coefficient R = 0.83, P < 0.001) and a 3.2-μm difference in RNFL thickness between the two eyes (R = 0.67, P < 0.001). Greater VF damage and thinner RNFL for each individual eye were associated with smaller response amplitude, slower velocity, and longer time to peak constriction and dilation after adjusting for age and sex (all P < 0.001). However, within-eye asymmetry of PLR between superonasal and inferonasal stimulation was not associated with corresponding within-eye differences in VF or RNFL.As measured by this particular device, the PLR is strongly correlated with VF functional testing and measurements of RNFL thickness.
View details for DOI 10.1167/iovs.13-12142
View details for PubMedID 23860751
View details for PubMedCentralID PMC4591738
Early lens extraction compared to standard treatment in acute primary angle closure.
The Cochrane database of systematic reviews
This is the protocol for a review and there is no abstract. The objectives are as follows: To compare the efficacy as well as harms of early lens extraction versus standard treatment in patients with acute primary angle closure.
View details for DOI 10.1002/14651858.CD010220
View details for PubMedID 25152692
View details for PubMedCentralID PMC4139041
Comparing approaches to screening for angle closure in older Chinese adults.
Eye (London, England)
2012; 26 (1): 96–100
Primary angle-closure glaucoma is expected to account for nearly 50% of bilateral glaucoma blindness by 2020. This study was conducted to assess the performance of the scanning peripheral anterior chamber depth analyzer (SPAC) and limbal anterior chamber depth (LACD) as screening methods for angle closure.This study assessed two clinical populations to compare SPAC, LACD, and gonioscopy: the Zhongshan Angle-closure Prevention Trial, from which 370 patients were eligible as closed-angle participants and the Liwan Eye Study, from which 72 patients were selected as open-angle controls. Eligible participants were assessed by SPAC, LACD, and gonioscopy.Angle status was defined by gonioscopy. Area under the receiver operating characteristic curve (AUROC) for SPAC was 0.92 (0.89-0.95) whereas AUROC for LACD was 0.94 (0.92-0.97). Using conventional cutoff points, sensitivity/specificity was 93.0%/70.8% for SPAC and 94.1%/87.5% for LACD. Sequential testing using both SPAC and LACD increased the specificity to 94.4% and decreased the sensitivity to 87.0%.SPAC has significantly lower specificity than LACD measurement using conventional cutoffs but interpretation of the findings can be performed by modestly trained personnel.
View details for DOI 10.1038/eye.2011.244
View details for PubMedID 21997356
View details for PubMedCentralID PMC3259582
Immediate changes in intraocular pressure after laser peripheral iridotomy in primary angle-closure suspects.
2012; 119 (2): 283–88
To determine the immediate changes in intraocular pressure (IOP) after laser peripheral iridotomy in primary angle-closure suspects.Prospective, randomized controlled trial (split-body design).Seven hundred thirty-four Chinese people 50 to 70 years of age.Primary angle-closure suspects underwent iridotomy using a neodymium:yttrium-aluminum-garnet laser in 1 randomly selected eye, with the fellow eye serving as a control. Intraocular pressure was measured using Goldmann applanation tonometry before treatment and 1 hour and 2 weeks after treatment. Total energy used and complications were recorded. Risk factors for IOP rise after laser peripheral iridotomy were investigated.Intraocular pressure.The proportion of treated eyes with an IOP spike (an elevation of ≥8 mmHg more than baseline) at 1 hour and 2 weeks after treatment was 9.8% (95% confidence interval [CI], 7.7-12.0) and 0.82% (95% CI, 0.2-1.5), respectively. Only 4 (0.54%) of 734 eyes (95% CI, 0.01-1.08) had an immediate posttreatment IOP of 30 mmHg or more and needed medical intervention. The average IOP 1 hour after treatment was 17.5±4.7 mmHg in the treated eyes, as compared with 15.2±2.6 mmHg in controls. At 2 weeks after treatment, these values were 15.6±3.4 mmHg in treated eyes and 15.1±2.7 mmHg in controls (P<0.001). No significant difference was detected in the baseline IOP of the treated and untreated eyes. Logistic regression showed that the incidence of IOP spike was associated with greater laser energy used and shallower central anterior chamber.Laser peripheral iridotomy in primary angle-closure suspects resulted in significant IOP rise in 9.8% and 0.82% of cases at 1 hour and 2 weeks, respectively. Eyes in which more laser energy and a higher number of laser pulses were used and those with shallower central anterior chambers were at increased risk for IOP spikes at 1 hour after laser peripheral iridotomy.
View details for DOI 10.1016/j.ophtha.2011.08.014
View details for PubMedID 22036632
View details for PubMedCentralID PMC3570569
Inequities in Cataract Surgery and Postsurgical Quality-of-Life Outcomes in Handan, China.
Asia-Pacific journal of ophthalmology (Philadelphia, Pa.)
2012; 1 (3): 147–51
This study aimed to describe the rate of cataract surgical coverage (CSC) and the quality-of-life (QoL) outcomes after cataract surgery in rural China.Cross-sectional study.A clustered, random sampling procedure was used to select 7557 Chinese patients aged 30 years and older from Handan, China. Comprehensive eye examinations, including standardized refraction and classification of lens characteristics, were offered to all eligible subjects. Visual impairment was defined as any individual with presenting visual acuity of less than 20/60 in the better-seeing eye. The main outcome measures were CSC rate and a summary measure assessing QoL in visually impaired (VI) participants.Of 5592 participants older than 40 years, there were 41 cataract patients operated on and 54 VI cataract patients not operated on. The CSC rate among individuals with VI was 43.2%. Older age was significantly negatively associated with a history of cataract surgery (adjusted odds ratio, 0.44 per 10-year increase in age; 95% confidence interval, 0.26-0.74). Women were less likely to have had cataract surgery compared with men, although not significantly (adjusted odds ratio, 0.44; 95% confidence interval, 0.17-1.12). The QoL summary measure was significantly better in the cataract group operated on than that not operated on (P < 0.01).There is a large unmet need for cataract surgery in rural Handan, China. Those who had surgery were more likely to have better QoL outcomes than those who did not. There is a potential need to promote cataract surgery and develop age- and sex-sensitive interventions in rural China.
View details for DOI 10.1097/APO.0b013e3182531e89
View details for PubMedID 24163787
View details for PubMedCentralID PMC3806141
Single versus sequential testing with scanning peripheral anterior chamber depth analyser, IOLMaster and anterior segment optical coherence tomography for the detection of narrow angles.
The British journal of ophthalmology
2011; 95 (10): 1410–14
Scanning peripheral anterior chamber depth analyser (SPAC), IOLMaster and anterior segment optical coherence tomography (AS-OCT) are devices that can screen non-invasively for narrow angles (NAs) and may reduce the need for gonioscopy, especially where the availability of ophthalmologists is limited. When used individually to detect NAs, neither SPAC, AS-OCT nor IOLMaster were able to achieve both high sensitivity and specificity when using gonioscopy as a gold standard.To assess whether sequential testing improves discrimination of NAs over single testing.In a prospective community-based cross-sectional study in Singapore, 2047 phakic right eyes underwent SPAC, IOLMaster and AS-OCT. NA eyes were defined as present when Shaffer scores were 0 or 1 in ≥ 2 quadrants on gonioscopy. Sensitivities and specificities of single and sequential testing were compared.At a fixed specificity of 95%, sensitivities in detecting NA eyes were 57.8% (95% CI 52.7% to 62.7%) for SPAC, 43.3% (95% CI 38.3% to 48.3%) for IOLMaster and 52.1% (95% CI 46.4% to 57.7%) for AS-OCT. After sequential testing using SPAC followed by AS-OCT, the sensitivity rose to 70.3% (95% CI 65.5% to 74.8%) while specificity remained at 94.3% (95% CI 93.1% to 95.4%), with sensitivity significantly higher than single testing alone (p<0.001).Sequential testing significantly improves the accuracy of detecting NAs and may be useful in screening settings.
View details for DOI 10.1136/bjo.2009.175869
View details for PubMedID 21242582
Prevalence and characteristics of primary angle-closure diseases in a rural adult Chinese population: the Handan Eye Study.
Investigative ophthalmology & visual science
2011; 52 (12): 8672–79
To investigate the prevalence and characteristics of primary angle-closure suspect (PACS), primary angle closure (PAC), and primary angle-closure glaucoma (PACG) in a rural population in China.In all, 6716 Han Chinese 30 years of age and older (5480 subjects 40 years of age and older) from 13 villages in Handan were randomly selected and completed an ophthalmologic examination, including visual acuity, intraocular pressure (IOP), slit-lamp examination, gonioscopy and stereoscopic photography, and visual field. PACS was defined as present if either eye had the posterior trabecular meshwork not visible for 180° or more on gonioscopy. PAC was present in an eye with PACS and peripheral anterior synechiae (PAS) and/or IOP ≥ 21 mm Hg, but without glaucomatous neuropathy (GON). PACG was defined as PAC with evidence of GON.The standardized prevalences of PACG, PAC, and PACS were 0.5% (95% confidence interval [CI]: 0.3-0.7%), 1.5% (95% CI: 1.2-1.8%), and 10.4% (95% CI: 9.6-11.2%) in those 40 years of age and older. The prevalence of all three conditions increased with age (P < 0.001). Females had much higher rates of PACS, PAC, and PACG (P < 0.05); 21 persons with PACG (65%) were blind in at least one eye: 13 were due to glaucoma and the other 8 likely had other causes.The prevalence of PACS, PAC, and PACG in this rural population is similar to what was previously reported in urban Chinese residents. Two thirds of those with PACG were blind in at least one eye. Strategies to detect and treat this preventable disease in rural China are needed.
View details for DOI 10.1167/iovs.11-7480
View details for PubMedID 21908580
Prevalence of primary open angle glaucoma in a rural adult Chinese population: the Handan eye study.
Investigative ophthalmology & visual science
2011; 52 (11): 8250–57
To estimate the prevalence and associations of primary open angle glaucoma (POAG) in a rural population of northern China.In a rural county in Handan, China, 6716 adults residing in 13 villages were randomly selected and participated in the study. All participants completed a comprehensive eye examination, including intraocular pressure (IOP), slit-lamp examination, and fundus evaluation. Visual fields were obtained with on glaucoma suspects.Sixty-five persons (1.2%) had POAG, with an adjusted prevalence of 1.0% (95% confidence interval [CI], 0.7% -1.3%) in those aged 40 years and older. Sex was not significantly associated with POAG (P > 0.05). Age (odds ratio [OR], 1.9; 95% CI, 1.4-2.5, for each 10-year increase), IOP (OR, 1.5; 95% CI 1.2-2.0 for each 5-mm Hg increase), axial length (OR, 1.3; 95% CI, 1.1-1.6), and moderate myopia (3.1-6.0 D; OR, 4.7; 95% CI, 1.6-13.5) increased the risk for POAG in multivariate analysis. The mean IOP of persons with POAG was 16.3 ± 3.5 mm Hg, and 90% of them presented with an IOP ≤ 21 mm Hg. Of those with POAG, 4.5% were blind from glaucoma in at least one eye.Approximately 1% of adults aged 40 years and older living in rural China have POAG. As seen in other populations, increasing age, higher IOP, greater axial length, and having myopia were associated with POAG. Given the rapid aging and myopic shift (acquired myopia) in China's population, POAG is likely to increase in prevalence in the coming decades.
View details for DOI 10.1167/iovs.11-7472
View details for PubMedID 21896871
A population-based assessment of 24-hour intraocular pressure among subjects with primary open-angle glaucoma: the handan eye study.
Investigative ophthalmology & visual science
2011; 52 (11): 7817–21
To describe the distribution of the 24-hour intraocular pressure (IOP) among subjects with primary open-angle glaucoma (POAG) in a population-based study in north China.All untreated POAG patients (n = 66) identified in the Handan Eye Study were invited to attend a follow-up study in which IOP was tested with a Goldmann applanation tonometer at 10 AM, 2 PM, 6 PM, 10 PM, 2 AM, and 6 AM.Forty-seven subjects with untreated POAG (47/66; 71.2%) attended the study. Of them, 39 (83.0%) had a peak IOP ≤ 21 mm Hg. The peak IOP (mean ± SD) was 18.4 ± 3.7 mm Hg. Peak IOP occurred in early morning in approximately 76.5% of the subjects (6 AM to 10 AM), and the trough occurred during night time in 70.2% of the subjects (10 PM to 2 AM). The 24-hour IOP (mean ± SD) was 15.4 ± 3.1 mm Hg and the mean fluctuation was 6.0 ± 2.2 mm Hg (range, 2-11 mm Hg). In the 22 persons with unilateral glaucoma, no significant differences were found in mean 24-hour IOP, peak IOP, trough IOP, or IOP fluctuation when comparing the glaucomatous eye with the nonglaucomatous eye (P > 0.05).About 80% of Chinese persons with POAG identified in a population-based study had maximum IOPs of 21 mm Hg or less over a 24-hour period. Twenty-four-hour IOP was similar between glaucomatous and contralateral nonglaucomatous eyes suggesting that factors other than IOP may play a role in the development of glaucomatous optic neuropathy in these eyes.
View details for DOI 10.1167/iovs.11-7528
View details for PubMedID 21873661
Choroidal thickness measured by spectral domain optical coherence tomography: factors affecting thickness in glaucoma patients.
2011; 118 (8): 1571–79
To measure choroidal thickness and to determine parameters associated with it.Cross-sectional study.Seventy-four glaucoma patients and glaucoma suspects.Spectral domain optical coherence tomography (SD-OCT) scans were obtained to estimate average choroidal thickness in a group of glaucoma suspects and glaucoma patients. The average thickness was calculated from enhanced depth SD-OCT images and manually analyzed with Image J software. Open-angle glaucoma, open-angle glaucoma suspect, primary angle-closure glaucoma, primary angle closure, and primary angle-closure suspect were defined by published criteria. Glaucoma suspects had normal visual fields bilaterally. Glaucoma was defined by specific criteria for optic disc damage and visual field loss in ≥1 eye. The most affected eye was analyzed for comparisons across individuals, and right/left and upper half/lower half comparisons were made to compare thickness against degree of visual field damage.Average macular and peripapillary choroidal thickness measured using SD-OCT.The choroidal-scleral interface was visualized in 86% and 96% of the macular and peripapillary scans, respectively. In multivariable linear regression analysis, the macular choroid was significantly thinner in association with 4 features: Longer eyes (22 μm per mm longer [95% confidence interval (CI), -33, -11]), older individuals (31 μm thinner per decade older [95% CI, -44, -17]), lower diastolic ocular perfusion pressure (26 μm thinner per 10 mmHg lower [95% CI, 8, 44]), and thicker central corneas (6 μm per 10 μm thicker cornea [95% CI, -10, 0]). The choroid was not significantly thinner in glaucoma patients than in suspects (14 μm [95% CI, -54, 26]; P = 0.5). Peripapillary choroidal thickness was not significantly different between glaucoma and suspect patients. Thickness was not associated with damage severity as estimated by visual field mean deviation or nerve fiber layer thickness, including comparisons of right with left eye or upper with lower values.Age, axial length, CCT, and diastolic ocular perfusion pressure are significantly associated with choroidal thickness in glaucoma suspects and glaucoma patients. Degree of glaucoma damage was not consistently associated with choroidal thickness.Proprietary or commercial disclosure may be found after the references.
View details for DOI 10.1016/j.ophtha.2011.01.016
View details for PubMedID 21492939
View details for PubMedCentralID PMC3139809