Henrietta Ho

Imaging of the Iridocorneal Angle with the RTVue Spectral Domain Optical Coherence Tomography

PURPOSE To determine the ability of the RTVue spectral domain optical coherence tomography (SDOCT) to image the anterior chamber angle (ACA). METHODS Consecutive subjects, recruited from glaucoma clinics, prospectively underwent ophthalmic evaluation including gonioscopy by an ophthalmologist and anterior chamber imaging with SDOCT, adapted with a corneal lens adapter (cornea anterior module-low magnification [CAM-L]) and anterior segment OCT (ASOCT), both performed by a technician. Two different ophthalmologists, masked to gonioscopy findings, assessed visualization of the scleral spur (SS), Schwalbes line (SL), and trabecular meshwork (TM) by the two modalities. The ability to detect a closed angle was compared with gonioscopy. RESULTS The average age (SD) of the 81 subjects enrolled was 64.1 (11.4) years; the majority were Chinese (91.4%) and female (61.7%). SDOCT images revealed the SS in 26.9% (56/324) of quadrants and the SL in 44.1% (143/324) of quadrants; in ASOCT images, the SS could be visualized in 69.1% (224/324) of quadrants (P < 0.0001), but the SL was undetectable. The TM was detected equally well (17.3%, P < 0.92) using either device. The angle status was gradable in only 41.7% images with SDOCT, compared with 71.3% of ASOCT images (P < 0.0001). ACA was classified as closed in 19.3% of quadrants (26/135) with SDOCT images and in 44.2% (102/231) with ASOCT images compared with 37.7% (122/324) on gonioscopy. When analyzing the horizontal quadrants only, both modalities agreed well with gonioscopy, 0.75 and 0.74, respectively (AC1 statistics). CONCLUSIONS The RTVue SDOCT allowed visualization of SL, TM, and SS. However, these landmarks were not detected in a large percentage of images.

The Spatial Profile of Macular Pigment in Subjects From a Singapore Chinese Population

PURPOSE To examine the spatial profile of macular pigment (MP) and its relationship with serum concentrations of lutein (L) and zeaxanthin (Z) in subjects from a Singapore Chinese population. METHODS In this cross-sectional study, the following details were recorded in 95 healthy subjects: sociodemographic, lifestyle information, body mass index (BMI), visual acuity, MP spatial profile using a macular densitometer, and serum L and Z. RESULTS The mean (SD) age of the population was 42.40 (± 13) years, ranging from 21 to 68 years. Females demonstrated significantly lower MP optical density (MPOD) than males (MPOD: females = 0.52 ± 0.17; males = 0.61 ± 0.21, P = 0.03). MP spatial profile was typical and atypical with central dip in 68 (85%) and 12 (15%) subjects, respectively. Age and BMI were found to be significant predictors for atypical MP spatial profile (age: odds ratio, OR = 1.06, 95% confidence interval, CI = 1.01-1.13, P = 0.04; BMI: OR = 1.17, 95% CI = 1.01-1.34, P = 0.03). A positive relationship was observed between MPOD and serum concentrations of L and Z, but only the latter relationship reached statistical significance (serum L: r = 0.12, P = 0.30; serum Z: r = 0.26, P = 0.02). CONCLUSIONS A central dip in MP spatial profile was observed with older age and higher BMI, the two known risk factors for AMD, suggesting that atypical MP spatial profile may be associated with an increased risk of AMD. Further studies with larger sample sizes are required to confirm these observations.

Association of Systemic Medication Use With Intraocular Pressure in a Multiethnic Asian Population: The Singapore Epidemiology of Eye Diseases Study

Importance There is limited understanding of the associations between systemic medication use and intraocular pressure (IOP) in the general population. Objective To examine the association between systemic medication use and IOP in a multiethnic Asian population. Design, Setting, and Participants In this post hoc analysis of the Singapore Epidemiology of Eye Diseases study, a population-based study of 10 033 participants (78.7% response rate) from 3 racial/ethnic groups (Chinese [recruited from February 9, 2009, through December 19, 2011], Malays [recruited from August 16, 2004, though July 10, 2006], and Indians [recruited from May 21, 2007, through December 29, 2009]), participants with glaucoma, previous ocular surgery, or trauma and an IOP asymmetry greater than 5 mm Hg between eyes were excluded. Intraocular pressure was measured using Goldmann applanation tonometry. An interviewer-administered questionnaire was conducted to collect data on medication and other variables. Data analysis was performed from August 1 through October 31, 2015. Main Outcomes and Measures Associations between medication and IOP were assessed using linear regression models adjusted for age, sex, body mass index, ethnicity, and the medical condition for which the medication was taken (angiotensin-converting enzyme inhibitors [ACEIs], angiotensin receptor blockers [ARBs], and &bgr;-blockers adjusted for blood pressure, statins adjusted for lipids, and biguanides, sulfonylureas, &agr;-glycosidase inhibitors [AGIs], and insulin adjusted for glycosylated hemoglobin). Medications associated with significant IOP differences were incorporated into regression models adjusted for concomitant use of multiple medications. Generalized estimating equation models were used to account for correlation between eyes. Results Of the 10 033 participants, we analyzed 8063 (mean [SD] age, 57.0 [9.6] years; 4107 female [50.9%]; 2680 Chinese [33.2%], 2757 Malay [34.2%], and 2626 Indian [32.6%] individuals). Systemic &bgr;-blocker use was independently associated with an IOP of 0.45 mm Hg lower (95% CI, −0.65 to −0.25 mm Hg; P < .001). Conversely, higher mean IOP was associated with use of ACEIs (0.33 mm Hg higher; 95% CI, 0.08 to 0.57 mm Hg; P = .008), ARBs (0.40 mm Hg higher; 95% CI, 0.40-0.75 mm Hg; P = .02), statins (0.21 mm Hg higher; 95% CI, 0.02-0.4 mm Hg; P = .03), and sulfonylureas (0.34 mm Hg higher; 95% CI, 0.05-0.63 mm Hg; P = .02). An interaction between medication classes for additive, synergistic, or antagonistic effects on IOP was not identified. Conclusions and Relevance Although systemic &bgr;-blocker use was associated with lower IOP and systemic ACEI, ARB, statin, and sulfonylurea use was associated with higher IOP in this study, the associations were modest at best. Only the associations with systemic hypoglycemic agents were greater than 1 mm Hg, a threshold that has translated to a 14% greater risk of incident glaucoma across 5 years in other studies. At this point, the effect of systemic medication on IOP in eyes with glaucoma is not well elucidated but important. Our findings indicate that patients with glaucoma may potentially be at risk of higher or lower IOP, depending on medication class, and this would in turn affect management of IOP control.

Retinopathy Signs Improved Prediction and Reclassification of Cardiovascular Disease Risk in Diabetes: A prospective cohort study

CVD risk prediction in diabetics is imperfect, as risk models are derived mainly from the general population. We investigate whether the addition of retinopathy and retinal vascular caliber improve CVD prediction beyond established risk factors in persons with diabetes. We recruited participants from the Singapore Malay Eye Study (SiMES, 2004–2006) and Singapore Prospective Study Program (SP2, 2004–2007), diagnosed with diabetes but no known history of CVD at baseline. Retinopathy and retinal vascular (arteriolar and venular) caliber measurements were added to risk prediction models derived from Cox regression model that included established CVD risk factors and serum biomarkers in SiMES, and validated this internally and externally in SP2. We found that the addition of retinal parameters improved discrimination compared to the addition of biochemical markers of estimated glomerular filtration rate (eGFR) and high-sensitivity C-reactive protein (hsCRP). This was even better when the retinal parameters and biomarkers were used in combination (C statistic 0.721 to 0.774, p = 0.013), showing improved discrimination, and overall reclassification (NRI = 17.0%, p = 0.004). External validation was consistent (C-statistics from 0.763 to 0.813, p = 0.045; NRI = 19.11%, p = 0.036). Our findings show that in persons with diabetes, retinopathy and retinal microvascular parameters add significant incremental value in reclassifying CVD risk, beyond established risk factors.

A comparison of two approaches to managing acute primary angle closure in Asian eyes.

Purpose To review the management regimes of acute primary angle closure (APAC) in two hospitals in Singapore, and to identify the incidence of and risk factors for progression to glaucomatous optic neuropathy. Methods We conducted a retrospective review of 40 patients from National University Hospital (NUH) and 52 patients from Singapore National Eye Centre (SNEC) who were diagnosed with APAC. Patients were treated with similar protocols of intensive medical therapy until laser peripheral iridotomy could be performed. In the event of failed medical treatment, patients at NUH only underwent laser iridoplasty. The 1-year outcomes were reviewed. Results The demographic features of patients and presenting intraocular pressures (IOP) were similar in both centers. More patients from NUH presented within 3 days of symptom onset, compared to those from SNEC (90.0% versus 71.2%, respectively) (P = 0.037). The mean ± standard deviation time to break the attack was 18.2 ± 32.9 hours at SNEC and 9.80 ± 10.6 hours at NUH (P = 0.11). The mean follow up duration was 18.8 ± 14.0 months. Nineteen patients (36.5%) from SNEC and six patients (22.5%) from NUH developed raised IOP (P = 0.032) within 1-year of the attack. Of these, glaucomatous optic neuropathy developed in thirteen patients (68.4%) from SNEC and all six patients (100%) from NUH. At final review, the mean IOP of the APAC eye was 14.8 ± 4.3 mmHg from SNEC and 13.4 ± 3.0 mmHg from NUH. There was no significant difference in final visual acuity or IOP between both groups. Conclusion Treatment strategies in both centers were effective in aborting an APAC attack. The development of raised IOP appears to be associated with a longer period of attack suggesting that greater urgency in aborting APAC attacks may entail better long term outcomes.

Altered Anterior Segment Biometric Parameters in Mice Deficient in SPARC

Purpose Secreted protein acidic and rich in cysteine (SPARC) and Hevin are structurally related matricellular proteins involved in extracellular matrix assembly. In this study, we compared the anterior chamber biometric parameters and iris collagen properties in SPARC-, Hevin- and SPARC-/Hevin-null with wild-type (WT) mice. Methods The right eyes of 53 WT, 35 SPARC-, 56 Hevin-, and 63 SPARC-/Hevin-null mice were imaged using the RTVue-100 Fourier-domain optical coherence tomography system. The parameters measured were anterior chamber depth (ACD), trabecular-iris space area (TISA), angle opening distance (AOD), and pupil diameter. Biometric data were analyzed using analysis of covariance and adjusted for age, sex, and pupil diameter. Expression of Col1a1, Col8a1, and Col8a2 transcripts in the irises was measured by quantitative polymerase chain reaction. Collagen fibril thickness was evaluated by transmission electron microscopy. Results Mice that were SPARC- and SPARC-/Hevin-null had 1.28- and 1.25-fold deeper ACD, 1.45- and 1.53-fold larger TISA, as well as 1.42- and 1.51-fold wider AOD than WT, respectively. These measurements were not significantly different between SPARC- and SPARC-/Hevin-null mice. The SPARC-null iris expressed lower Col1a1, but higher Col8a1 and Col8a2 transcripts compared with WT. Collagen fibrils in the SPARC- and SPARC-/Hevin-null irises were 1.5- and 1.7-fold thinner than WT, respectively. The Hevin-null iris did not differ from WT in these collagen properties. Conclusions SPARC-null mice have deeper anterior chamber as well as wider drainage angles compared with WT. Therefore, SPARC plays a key role in influencing the spatial organization of the anterior segment, potentially via modulation of collagen properties, while Hevin is not likely to be involved.

Distinct iris gene expression profiles of primary angle closure glaucoma and primary open angle glaucoma and their interaction with ocular biometric parameters

This study aimed to evaluate differences in iris gene expression profiles between primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) and their interaction with biometric characteristics.

Distinct iris gene expression profiles of PACG and POAG and their interaction with ocular biometric parameters

This study aimed to evaluate differences in iris gene expression profiles between primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) and their interaction with biometric characteristics.

Ocular 'Roid Rage

Corticosteroids use can cause raised intraocular pressure (IOP), leading to glaucoma. We present a case report of steroid induced glaucoma in a young male with keratoconjunctivitis (VKC). Our patient was uncompliant with instructions to stop steroid use, initially started for VKC treatment, and required aggressive medical and surgical intervention for IOP control. He eventually progressed to severe glaucomatous optic neuropathy and eventual tunnel vision. Steroid induced glaucoma is an important and frequently encountered condition in ophthalmology clinics. This report serves to remind all physicians of the dangers of steroid eye drop usage.