Pull-through insertion of EndoArt for complex eyes

Purpose

To report an alternative technique to implant the EndoArt using a pull-through insertion. This technique is helpful in complex eyes, especially in eyes with unstable iris lens diaphragm.

Observation

We present a case of advanced pseudophakic bullous keratopathy with aniridia, previous vitrectomy, and tube implants in which the initial attempt to implant the EndoArt failed, and the device was lost to the vitreous cavity. An alternative surgical technique, a pull-through insertion, was used to implant a second device successfully. The patient was followed over a period of 1 year. Corneal edema gradually improved over time, and all epithelial bullae resolved. The central corneal thickness (CCT) decreased from 911um to 691 μm.

Conclusion and Importance

EndoArt is a treatment for endothelial failure in complex eyes. In addition, the pull-through insertion technique can help improve control over the implant in very complicated eyes.

A Multitask Deep-Learning System to Classify Diabetic Macular Edema for Different Optical Coherence Tomography Devices: A Multicenter Analysis

OBJECTIVE

Diabetic macular edema (DME) is the primary cause of vision loss among individuals with diabetes mellitus (DM). We developed, validated, and tested a deep learning (DL) system for classifying DME using images from three common commercially available optical coherence tomography (OCT) devices.

RESEARCH DESIGN AND METHODS

We trained and validated two versions of a multitask convolution neural network (CNN) to classify DME (center-involved DME [CI-DME], non-CI-DME, or absence of DME) using three-dimensional (3D) volume scans and 2D B-scans, respectively. For both 3D and 2D CNNs, we used the residual network (ResNet) as the backbone. For the 3D CNN, we used a 3D version of ResNet-34 with the last fully connected layer removed as the feature extraction module. A total of 73,746 OCT images were used for training and primary validation. External testing was performed using 26,981 images across seven independent data sets from Singapore, Hong Kong, the U.S., China, and Australia.

RESULTS

In classifying the presence or absence of DME, the DL system achieved area under the receiver operating characteristic curves (AUROCs) of 0.937 (95% CI 0.920-0.954), 0.958 (0.930-0.977), and 0.965 (0.948-0.977) for the primary data set obtained from CIRRUS, SPECTRALIS, and Triton OCTs, respectively, in addition to AUROCs >0.906 for the external data sets. For further classification of the CI-DME and non-CI-DME subgroups, the AUROCs were 0.968 (0.940-0.995), 0.951 (0.898-0.982), and 0.975 (0.947-0.991) for the primary data set and >0.894 for the external data sets.

CONCLUSIONS

We demonstrated excellent performance with a DL system for the automated classification of DME, highlighting its potential as a promising second-line screening tool for patients with DM, which may potentially create a more effective triaging mechanism to eye clinics.

Longitudinal Structural and Microvascular Observation in RCS Rat Eyes Using Optical Coherence Tomography Angiography

Purpose

To evaluate the change of retinal thickness and ocular microvasculature in a rat model of retinitis pigmentosa using swept source optical coherence tomography angiography (SS-OCTA)

Methods

Three-weeks-old Royal College of Surgeons (RCS) rats (n = 8) and age-matched control rats (n = 14) were imaged by a prototype SS-OCTA system. Follow-up measurements occurred every three weeks on six RCS rats until week 18, and cross-sectional measurements were conducted on control rats. Thicknesses of different retinal layers and the total retina were measured. The enface angiograms from superficial vascular plexiform (SVP) and deep capillary plexiform (DCP) were analyzed, and the image sharpness was also extracted from the choroidal angiograms. Immunohistochemical analysis was done in the RCS rats after week 18, as well as in three-week-old RCS rats and age-matched controls.

Results

In RCS rats, the thicknesses of the ganglion cell complex, the nuclear layer, the debris/photoreceptor layer and the total retina decreased over the weeks (P < 0.001). The SVP metrics remained unchanged whereas the DCP metrics decreased significantly over the weeks (P < 0.001). The immunohistochemical analysis confirmed our OCTA findings of capillary dropout in the DCP. The choroidal plexus appeared indistinct initially due to scattering of light at the intact retinal pigment epithelium (RPE) and became more visible after week nine probably due to RPE degeneration. Loss of choriocapillaris was visualized at week 18. In control rats, no vascular change was detected, but nuclear layers, photoreceptor layers and total retina showed slight thinning with age (P < 0.001).

Conclusions

Photoreceptor degeneration in RCS rats was associated with the loss of capillaries in DCP, but not in SVP. The OCTA imaging allows for the characterization of structural and angiographic changes in rodent models.

Diabetic Macular Edema Management in Asian Population: Expert Panel Consensus Guidelines

PURPOSE

The aim of this consensus article was to provide comprehensive recommendations in the management of diabetic macular edema (DME) by reviewing recent clinical evidence.

DESIGN

A questionnaire containing 47 questions was developed which encompassed clinical scenarios such as treatment response to anti-vascular endothelial growth factor and steroid, treatment side effects, as well as cost and compliance/reimbursement in the management of DME using a Dephi questionnaire as guide.

METHODS

An expert panel of 12 retinal specialists from Singapore, Malaysia, Philippines, India and Vietnam responded to this questionnaire on two separate occasions. The first round responses were compiled, analyzed and discussed in a round table discussion where a consensus was sought through voting. Consensus was considered achieved, when 9 of the 12 panellists (75%) agreed on a recommendation.

RESULTS

The DME patients were initially profiled based on their response to treatment, and the terms target response, adequate response, nonresponse, and inadequate response were defined. The panellists arrived at a consensus on various aspects of DME treatment such as need for classification of patients before treatment, first-line treatment options, appropriate time to switch between treatment modalities, and steroid-related side effects based on which recommendations were derived, and a treatment algorithm was developed.

CONCLUSIONS

This consensus article provides comprehensive, evidence-based treatment guidelines in the management of DME in Asian population. In addition, it also provides recommendations on other aspects of DME management such as steroid treatment for stable glaucoma patients, management of intraocular pressure rise, and recommendations for cataract development.

Agreement in Measures of Macular Perfusion between Optical Coherence Tomography Angiography Machines

We evaluated the agreements in foveal avascular zone (FAZ) area and vessel density (VD) parameters (within the superficial capillary plexus region), between two widely used optical coherence tomography angiography machines. Participants who attended the Singapore Malay Eye Study III between 29th March and 6th August 2018, were enrolled in this study. Participants underwent fovea-centered 6×6-mm macular cube scan, using both AngioVue and Cirrus HDOCT machines. Scans were analyzed automatically using built-in review software of each machine. 177 eyes (95 participants) without retinal diseases were included for final analysis. Mean FAZ area was 0.38 ± 0.11 mm² and 0.30 ± 0.10 mm², based on AngioVue and Cirrus HDOCT, respectively. Mean parafoveal VD was 0.50 ± 0.04 in Angiovue, and 0.43 ± 0.04 in Cirrus HDOCT. Cirrus HDOCT measurements were consistently lower than those by AngioVue, with a mean difference of −0.08 (95% limits of agreement [LOA], −0.30–0.13) mm² for FAZ area, and −0.07 (95% LOA, −0.17–0.03) for parafoveal VD. Intraclass correlation coefficients for FAZ area and parafoveal VD were 0.33 and 0.07, respectively. Our data suggest that agreements between AngioVue and Cirrus HDOCT machines were poor to fair, thus alternating use between these two machines may not be recommended especially for follow up evaluations.

Quantitative Microvascular Analysis With Wide-Field Optical Coherence Tomography Angiography in Eyes With Diabetic Retinopathy

IMPORTANCE

Wide-field optical coherence tomographic angiography (OCTA) may provide insights to peripheral capillary dropout in eyes with diabetic retinopathy (DR).

OBJECTIVE

To describe the diagnostic performance of wide-field OCTA with and without large vessel removal for assessment of DR in persons with diabetes.

DESIGN, SETTING, AND PARTICIPANTS

This case-control study was performed from April 26, 2018, to April 8, 2019, at a single tertiary eye center in Singapore. Case patients were those with type 2 diabetes for more than 5 years and bilateral DR diagnosed by fundus imaging; control participants included those with no self-reported history of diabetes, a fasting glucose level within the normal range in the past year, and no ocular pathologic findings. A wide-field (12 × 12-mm2) fovea-centered scan was performed using a prototype swept source OCTA system. Retinal microvasculature was examined by separating the angiograms into large vessels, capillaries, and capillary dropout regions.

MAIN OUTCOMES AND MEASURES

Area under the receiver operating characteristic curve (AUC) for DR severity discrimination using wide-field vascular metrics. Retinal perfusion density (RPD), capillary perfusion density (CPD), large vessel density (LVD), and capillary dropout density (CDD) were calculated. Low-contrast regions were excluded from the calculation.

RESULTS

A total of 49 eyes in 27 control participants (17 male [63.0%]; mean [SD] age, 59.96 [7.63] years; age range, 44-79 years) and 76 eyes in 47 patients with diabetes (29 male [61.7%]; mean [SD] age, 64.36 [8.08] years; range, 41-79 years) were included. Among eyes in patients with diabetes, 23 were in those with diabetes but no DR, 25 in those with mild nonproliferative DR, and 28 in those with moderate to severe nonproliferative DR. There was no difference in RPD, CPD, LVD, and CDD between the control group and the group with diabetes and no DR. There was a stepwise decrease in RPD, CPD, and CDD in the diabetes with no DR, mild nonproliferative DR, and moderate to severe nonproliferative DR groups, whereas LVD was not associated with DR staging. The nonproliferative DR group had decreased RPD, CPD, and CDD compared with the control group. The CPD had higher AUCs than RPD for discriminating diabetes with nonproliferative DR (combined mild and moderate to severe nonproliferative DR) vs no DM (AUC, 0.92 [95% CI, 0.87-0.98] vs 0.89 [95% CI, 0.83-0.95], P = .01), diabetes with no DR vs mild nonproliferative DR (AUC, 0.81 [95% CI, 0.68-0.94] vs 0.77 [95% CI, 0.64-0.91], P = .18), and mild nonproliferative DR vs moderate to severe nonproliferative DR (AUC, 0.82 [95% CI, 0.71-0.94] vs 0.78 [95% CI, 0.65-0.91], P = .01) but similar AUCs for no DM vs diabetes with no DR. The total perfusion density and CPD in wide-field OCTA had better discriminative power than the central 6 × 6-mm2 field (CPD, 0.89 [95% CI, 0.83-0.95] vs 0.84 [95% CI, 0.77-0.92], P = .06; total perfusion density, 0.93 [95% CI, 0.87-0.98] vs 0.90 [95% CI, 0.83-0.96], P = .06).

CONCLUSIONS AND RELEVANCE

The findings suggest that wide-field OCTA provides information on microvascular perfusion and may be useful for detecting predominant peripheral capillary dropout in eyes with nonproliferative DR. A vascular selectivity approach excluding the large vessels may improve the discriminative power for different stages of DR.

Multiethnic Genome-Wide Association Study of Diabetic Retinopathy Using Liability Threshold Modeling of Duration of Diabetes and Glycemic Control

To identify genetic variants associated with diabetic retinopathy (DR), we performed a large multiethnic genome-wide association study. Discovery included eight European cohorts (n = 3,246) and seven African American cohorts (n = 2,611). We meta-analyzed across cohorts using inverse-variance weighting, with and without liability threshold modeling of glycemic control and duration of diabetes. Variants with a P value <1 × 10-5 were investigated in replication cohorts that included 18,545 European, 16,453 Asian, and 2,710 Hispanic subjects. After correction for multiple testing, the C allele of rs142293996 in an intron of nuclear VCP-like (NVL) was associated with DR in European discovery cohorts (P = 2.1 × 10-9), but did not reach genome-wide significance after meta-analysis with replication cohorts. We applied the Disease Association Protein-Protein Link Evaluator (DAPPLE) to our discovery results to test for evidence of risk being spread across underlying molecular pathways. One protein-protein interaction network built from genes in regions associated with proliferative DR was found to have significant connectivity (P = 0.0009) and corroborated with gene set enrichment analyses. These findings suggest that genetic variation in NVL, as well as variation within a protein-protein interaction network that includes genes implicated in inflammation, may influence risk for DR.

An overview of the clinical applications of optical coherence tomography angiography

Optical coherence tomography angiography (OCTA) has emerged as a novel, non-invasive imaging modality that allows the detailed study of flow within the vascular structures of the eye. Compared to conventional dye angiography, OCTA can produce more detailed, higher resolution images of the vasculature without the added risk of dye injection. In our review, we discuss the advantages and disadvantages of this new technology in comparison to conventional dye angiography. We provide an overview of the current OCTA technology available, compare the various commercial OCTA machines technical specifications and discuss some future software improvements. An approach to the interpretation of OCTA images by correlating images to other multimodal imaging with attention to identifying potential artefacts will be outlined and may be useful to ophthalmologists, particularly those who are currently still unfamiliar with this new technology. This review is based on a search of peer-reviewed published papers relevant to OCTA according to our current knowledge, up to January 2017, available on the PubMed database. Currently, many of the published studies have focused on OCTA imaging of the retina, in particular, the use of OCTA in the diagnosis and management of common retinal diseases such as age-related macular degeneration and retinal vascular diseases. In addition, we describe clinical applications for OCTA imaging in inflammatory diseases, optic nerve diseases and anterior segment diseases. This review is based on both the current literature and the clinical experience of our individual authors, with an emphasis on the clinical applications of this imaging technology.

Diabetic macular oedema

Diabetic macular oedema, characterised by exudative fluid accumulation in the macula, is the most common form of sight-threatening retinopathy in people with diabetes. It affects one in 15 people with diabetes resulting in more than 20 million cases worldwide. Few epidemiological studies have been done to specifically investigate risk factors for diabetic macular oedema, although poor glycaemic and blood pressure control are associated with the presence and development of the disorder. The pathophysiological processes begin with chronic hyperglycaemia, and interplay between vascular endothelial growth factor (VEGF) and inflammatory mediators. Non-invasive imaging using optical coherence tomography has allowed clinicians to detect mild levels of diabetic macular oedema in order to monitor progress and guide treatment. Although focal or grid laser photocoagulation was the traditional mode of treatment, intraocular pharmacotherapy with anti-VEGF agents is now the standard of care. However, these therapies are expensive and resource intensive. Emerging therapeutic strategies include improving efficacy and duration of VEGF suppression, targeting alternative pathways such as inflammation, the kallikrein-kinin system, the angiopoietin-Tie2 system, and neurodegeneration, and using subthreshold and targeted laser therapy. Ongoing research should lead to improvements in screening, diagnosis, and management of diabetic macular oedema.

Prevalence and determinants of undiagnosed diabetic retinopathy and vision-threatening retinopathy in a multiethnic Asian cohort: the Singapore Epidemiology of Eye Diseases (SEED) study

OBJECTIVE

To determine the prevalence and risk factors of undiagnosed diabetic retinopathy (DR), in particular vision-threatening DR (VTDR) in a multiethnic Asian cohort.

DESIGN

A population-based survey of 3353 Chinese, 3280 Malays and 3400 Indians (73.6% response) aged 40-80 years residing in Singapore. Diabetes mellitus (DM) was defined as random glucose ≥11.1 mmol/L, use of diabetic medication or a previous physician diagnosis. DR severity was graded from retinal photographs following the modified Airlie House classification. VTDR was defined as the presence of severe non-proliferative DR (NPDR), proliferative DR (PDR) or clinically significant macular oedema (CSMO), using the Eye Diseases Prevalence Research Group definition. Participants were deemed 'undiagnosed' if they reported no prior physician diagnosis in structured interviews, in those with the condition.

RESULTS

Of 10 033 participants, 2376 had DM (23.7%), of which 805 (33.9%) had DR. Among 2376 with DM, 11.1% (n=263) were undiagnosed. Among 805 with DR, 671 (83.3%) were undiagnosed. Among 212 with VTDR, 59 (27.3%) were undiagnosed. In multivariate models, factors associated with undiagnosed VTDR were higher low-density lipoprotein (LDL) cholesterol (OR=1.53, 95% CI 0.99 to 2.35, p=0.05) and absence of visual impairment or blindness in any eye in terms of best-corrected vision OR=3.00, 95% CI 1.47 to 6.11, p=0.003).

CONCLUSIONS

In this community, a quarter with VTDR is undiagnosed, and 8 in 10 with any DR are undiagnosed, compared with only 1 in 10 with DM undiagnosed. These findings suggest that screening for diabetes is successful, while screening for DR is currently inadequate in our population. Public health strategies to aid early diagnosis of DR in Singapore are urgently warranted to reduce blindness due to diabetes.

New loci and coding variants confer risk for age-related macular degeneration in East Asians

Age-related macular degeneration (AMD) is a major cause of blindness, but presents differently in Europeans and Asians. Here, we perform a genome-wide and exome-wide association study on 2,119 patients with exudative AMD and 5,691 controls, with independent replication in 4,226 patients and 10,289 controls, all of East Asian descent, as part of The Genetics of AMD in Asians (GAMA) Consortium. We find a strong association between CETP Asp442Gly (rs2303790), an East Asian-specific mutation, and increased risk of AMD (odds ratio (OR)=1.70, P=5.60 × 10⁻²²). The AMD risk allele (442Gly), known to protect from coronary heart disease, increases HDL cholesterol levels by 0.17 mmol l⁻¹ (P=5.82 × 10⁻²¹) in East Asians (n=7,102). We also identify three novel AMD loci: C6orf223 Ala231Ala (OR=0.78, P=6.19 × 10⁻¹⁸), SLC44A4 Asp47Val (OR=1.27, P=1.08 × 10⁻¹¹) and FGD6 Gln257Arg (OR=0.87, P=2.85 × 10⁻⁸). Our findings suggest that some of the genetic loci conferring AMD susceptibility in East Asians are shared with Europeans, yet AMD in East Asians may also have a distinct genetic signature.

Age-related macular degeneration (AMD) is a major cause of blindness worldwide. Here, the authors carry out a two-stage genome-wide association study for AMD and identify three new AMD risk loci, highlighting the shared and distinct genetic basis of the disease in East Asians and Europeans.

SUBRETINAL NEOVASCULARIZATION IN MACULAR TELANGIECTASIA TYPE 2: OPTICAL COHERENCE TOMOGRAPHIC ANGIOGRAPHY AND TREATMENT RESPONSE

PURPOSE

To report the optical coherence tomographic angiography findings and response to treatment in a case of macular telangiectasia Type 2 with subretinal neovascularization.

METHODS

Case report.

RESULTS

A 64-year-old man with macular telangiectasia Type 2 developed subretinal neovascularization, which was imaged on optical coherence tomographic angiography. He was treated with intravitreal aflibercept, and there was a remarkable reduction of flow in the subretinal neovascular network on optical coherence tomographic angiography.

CONCLUSION

Optical coherence tomographic angiography provides detailed information on the retinal microvasculature and subretinal neovascularization in macular telangiectasia Type 2. It can be used to assess response to treatment.

Comparison of keratometric and pachymetric parameters with Scheimpflug imaging in normal and keratoconic Asian eyes

PURPOSE

To evaluate the keratometric and pachymetric parameters of keratoconic corneas of Asian eyes with the Scheimpflug imaging camera.

PATIENTS AND METHODS

This is a cross-sectional study of 22 eyes with Amsler-Krumeich stage 1 keratoconus and 48 eyes from normal subjects conducted in a tertiary eye hospital. A rotating Scheimpflug imaging system, the Pentacam, was used to evaluate all eyes for tomographic parameters, as well as pachymetric progression indices (PPI) and Ambrósio relational thickness (ART).

RESULTS

All PPI and ART parameter values were significantly different between study and control groups. Cornea minimum radius of curvature, absolute distance from corneal apex to thinnest location, as well as the distance from corneal apex to thinnest location in Y-axis also demonstrated statistically significant differences. The mean ART values for keratoconus eyes were 241 μm (ART-maximum) and 352 μm (ART-average), falling within previously reported best cutoff values for detecting keratoconus. On receiver operating characteristics curve analysis, the area under the curve values were highest for PPI and ART parameters.

CONCLUSION

There are significant differences in tomographic parameters between stage 1 keratoconic and normal Asian eyes. Pachymetric indices such as the PPI and the ART index can serve as additional tools in differentiating keratoconic from normal eyes. The findings validate the usefulness of the ART in identifying keratoconic eyes in Asians.

Correlation of anterior segment optical coherence tomography measurements with graft trephine diameter following descemet stripping automated endothelial keratoplasty

Background

To assess repeatability of the Zhongshan Assessment Program (ZAP) software measurement of Anterior Segment Optical Coherence Tomography (ASOCT) images and correlate with graft trephine diameter following Descemet Stripping Automated Endothelial Keratoplasty (DSAEK)

Methods

Retrospectively evaluated interventional case series. 121 consecutive eyes undergoing DSAEK over a 26 month period underwent ASOCT imaging 1month after their surgery. ASOCT images were processed using ZAP software which measured the graft and cornea parameters including anterior and posterior graft arc length and cord length, posterior cornea arc length (PCAL) and anterior chamber width.

Results

The graft measurements showed good repeatability on ASOCT using ZAP with high intra class coefficient and small variation in the coefficient of variation. On ASOCT, the mean recipient PCAL was 12.99+/−0.69mm and the anterior chamber width was 11.16+/−0.57mm. The mean Graft anterior arc length was 9.69+/−0.66mm and the mean Graft anterior cord length was 8.92+/−2.94mm. The mean graft posterior arc length was 9.24+/−0.75mm and the mean graft posterior cord length was 8.15+/−0.57mm. Graft posterior arc length (rho=0.788, p< 0.001) correlated best with intra-operative graft trephine diameter. The mean ratio of posterior graft arc length to PCAL was 0.712 +/− 0.056.

Conclusions

We have validated the repeatability of the ZAP software for DSAEK graft measurements from ASOCT images and shown that the graft arc length parameters calculated from the ASOCT images correlate well with the intra-operative graft trephine diameter. This software may help surgeons determine the optimal DSAEK graft size based on pre-operative ASOCT measurements of the recipient eye.

Determinants of lens vault and association with narrow angles in patients from Singapore

PURPOSE

To describe the distribution and determinants of lens vault and to investigate the association of lens vault with narrow angles.

DESIGN

Prospective cross-sectional study.

METHODS

Phakic subjects 50 years and older were evaluated at a primary healthcare clinic with gonioscopy, partial laser interferometry, and anterior segment optical coherence tomography (AS-OCT). Narrow angles were defined as posterior trabecular meshwork not visible for ≥2 quadrants on non-indentation gonioscopy. Lens vault was defined as the perpendicular distance between the anterior pole of the crystalline lens and the horizontal line joining the 2 scleral spurs on horizontal AS-OCT scans. Analysis of covariance, multivariate logistic regression, and area under the receiver operating characteristic curves (AUC) were performed.

RESULTS

Of the 2047 subjects recruited, 582 were excluded because of poor image quality or inability to locate scleral spurs, leaving 1465 subjects for analysis. Eyes with narrow angles had greater lens vault compared to eyes with open angles (775.6 µm vs 386.5 µm, P < .0001). Women had significantly greater lens vault than men (497.28 µm vs 438.56 µm, P < .001), and lens vault increased significantly with age (P for trend <.001). Adjusted for age and sex, significant associations with greater lens vault were shorter axial length, shallower anterior chamber depth(ACD), higher intraocular pressure, and more hyperopic spherical equivalent (all P < .001). On multivariate analysis, subjects with lens vault >667.6 µm were more likely to have narrow angles (OR 2.201, 95% CI: 1.070-4.526) compared to those with lens vault ≤462.7 µm. The AUC for lens vault (0.816) and ACD (0.822) for detecting narrow angles were similar (P = .582).

CONCLUSIONS

Lens vault was independently associated with narrow angles and may be useful in screening to detect eyes with narrow angles.

Blindness and long-term progression of visual field defects in chinese patients with primary angle-closure glaucoma

PURPOSE

To investigate the long-term rates of blindness and visual field (VF) progression in treated primary angle-closure glaucoma (PACG) patients.

DESIGN

Retrospective observational case series.

METHODS

PACG patients with ≥10 years of follow-up were analyzed. All VFs (static automated perimetry, central 24-2 threshold test) performed were reviewed and reliable VFs (fixation losses <20%, false positives and false negatives <33%) were scored using the Advanced Glaucoma Intervention Study (AGIS) system. Progression of a VF defect was defined as a change of ≥4 from baseline on 2 consecutive VF tests.

RESULTS

From the 137 eyes of 87 patients with PACG with ≥10 years of follow-up identified, 6% and 30.1% were blind based on initial visual acuity (VA) and VF criteria respectively and 12.0% had an initial AGIS score of 20; these were excluded. Eighty-three eyes from 57 patients (all Chinese, mean age 59.9 ± 8.2 years, 67.5% female) were analyzed. The mean AGIS score was 5.14 ± 4.37 at baseline. VF deterioration was detected in 27 eyes (32.5%) of 21 patients, with 4.8% and 7.2% of eyes progressing to blindness based on VA and VF criteria respectively. On Cox regression, eyes with VF progression had higher mean overall IOP (P < .001), and higher prevalence of previous acute angle closure (AAC, P = .008).

CONCLUSIONS

Over 10 years, a third of PACG patients were found to have VF progression, with 7% progressing to blindness while on treatment. Eyes with higher mean overall IOP and a history of previous AAC were more likely to have VF progression.

Rosiglitazone toxicity: accidental overdose leading to macular edema

BACKGROUND/PURPOSE

To highlight the clinical effects of rosiglitazone overdose.

METHODS

Case report, observational.

RESULTS

A 60-year-old Chinese man accidentally ingested 20 mg rosiglitazone. His usual dose was 2 mg once in the morning. Complications of drug overdose were monitored. He consequently developed right mild macular edema. This resolved spontaneously without laser treatment. No systemic toxicity, hypoglycemia, or peripheral edema was observed.

CONCLUSION

Rosiglitazone overdose causes acute macular edema that resolves spontaneously.

Diabetes, metabolic abnormalities, and glaucoma

OBJECTIVE

To examine the relationship of diabetes mellitus and metabolic abnormalities with intraocular pressure and glaucoma.

METHODS

A population-based study was conducted in 3280 (78.7% response) Malay adults aged 40 to 80 years. Diabetes was defined as a random serum glucose level of 200 mg/dL or greater or physician diagnosis of diabetes mellitus. Metabolic abnormalities including body mass index, lipid levels, and blood pressure were measured. Glaucoma was defined from a standardized examination by means of the International Society for Geographical and Epidemiological Ophthalmology criteria.

RESULTS

There were 764 persons (23.3%) who had diabetes. After controlling for age, sex, education, smoking, central corneal thickness, and diabetes treatment, intraocular pressure was higher in persons with than without diabetes (16.7 vs 15.0 mm Hg, P < .001) and in those with higher serum glucose levels (P < .001), glycosylated hemoglobin concentrations (P < .001), total cholesterol levels (P = .001), triglyceride levels (P = .002), and body mass index (P = .001). However, the prevalence of glaucoma was similar between persons with and without diabetes (4.7% vs 4.5%). In multivariate logistic regression models adjusting for age, sex, education, smoking, central corneal thickness, and diabetes treatment, diabetes was not associated with glaucoma (odds ratio, 1.00; 95% confidence interval, 0.63-1.61).

CONCLUSION

These data suggest that, although diabetes and metabolic abnormalities may be associated with a small increase in intraocular pressure, they are not significant risk factors for glaucomatous optic neuropathy.

Is routine pupil dilation safe among asian patients with diabetes?

PURPOSE

To investigate the risk of acute angle closure (AAC), changes in intraocular pressure (IOP), and factors associated with these outcomes after routine pupil dilation in a cohort of Asian subjects with diabetes mellitus.

METHODS

The study was a prospective observational case series of 1910 consecutive Asian subjects newly referred for assessment of diabetic retinopathy at a tertiary clinic. All subjects underwent routine pupil dilation unless there was a prior history of angle-closure glaucoma. Noncontact air-puff tonometry was used to assess IOP, which was measured by the same observer before and 1 hour after pupil dilation. Subjects were assessed for signs and symptoms of AAC before leaving the clinic, and their charts were also subsequently reviewed for revisits with AAC.

RESULTS

Of the 1910 subjects who participated, none developed AAC. Sixty-nine subjects (3.6%, 95% CI: 2.8%-4.5%) showed an increase in IOP of >or=5 mm Hg in the either eye, 37 subjects (1.9%, 95% CI: 1.4%-2.6%) had a postdilation IOP >25 mm Hg in either eye, and only 10 subjects (0.52%, 95% CI: 0.25%-0.96%) had an increase in IOP >or=5 mm Hg and had a postdilation IOP >25 mm Hg in either eye. The level of predilation IOP and a known history of glaucoma were significant risk factors for a postdilation IOP >or=25 mm Hg.

CONCLUSIONS

In this cohort of Asian persons with diabetes, the risk of AAC was insignificant after routine dilation of pupils for fundus examination. These data substantiate the safety of routine dilation of pupils in Asian patients with diabetes.

Intracranial laterally based supratentorial neurenteric cyst

Neurenteric cysts are rare developmental cysts lined by endodermal derived epithelium. We present the case of a 68-year-old patient presenting with seizures who was found to have an extra-axial low density lesion with associated wall calcification on CT. Aspiration and biopsy of the cyst revealed a neurenteric cyst. Such lesions of the lateral supratentorial convexity are extremely rare and calcification has not been previously reported in these intracranial cysts.

[A study of quality standards for fuyanke granule]

OBJECTIVE

To establish the quality standards for fuyanke(FYK) granule.

METHODS

The phellodendron Chinese schneid, polygonum cuspidatum, sieb. et Zucc and glycyrrihza uralensis fisch in FYK granule were identified by thin-layer chromatography(TLC). The contents of berberine were determined by thin-layer chromatographic scanning(TLCs).

RESULTS

The average recovery rate was 97.86%, and the relative standard deviation 1.96%.

CONCLUSION

The method is simple, accurate and reliable.

[Determination of tetrandrine in human plasma by high-performance liquid chromatography]

The paper reports the determination of tetrandrine by high performance liquid chromatography (HPLC). A C18 column was used and the mobile phase was methanol-water(80:20) containing 0.03% triethylamine, detective wave was at 282 nm, the internal standard was diazepam, the sample was extracted with ether. The linear range was from 0.289 microgram.ml-1 to 4.618 micrograms.ml-1, the average recovery rate was 95.8%. The coefficients of variation of within-day and day-to-day were less than 5%. This method is simple, rapid and accurate. It can be used in biomedical sample analysis of tetrandrine.

Hepatitis B virus variants with lamivudine-related mutations in the DNA polymerase and the 'a' epitope of the surface antigen are sensitive to ganciclovir

Lamivudine is a new antiviral agent effective against hepatitis B viral (HBV) infections but can result in virus-drug resistance associated with mutations in the conserved 'YM552DD' motif of the HBV DNA polymerase. Due to their overlapping coding regions in the HBV genome, mutations in the DNA polymerase may result in substitutions in the hepatitis B surface antigen (HBsAg), albeit outside the antigenic 'a' epitope. Here we report the identification of a novel type of lamivudine-related mutations located in both the polymerase (YM552DD-->Y1552DD) and the 'a' epitope of HBsAg (Gly130-->Asp130). The same virus carried a HBsAg Gly145-->Arg145 mutation prior to therapy. Both the wild type HBV and lamivudine-related mutants with the Gly145-->Arg145 HBsAg mutation were suppressed following ganciclovir treatment, indicating a beneficial additive effect of both drugs against different forms of HBV mutants.

Comparison of cAMP receptor protein (CRP) and a cAMP-independent form of CRP by Raman spectroscopy and DNA binding

The secondary structures of the cAMP receptor protein (CRP), a complex of CRP and cAMP, and a cAMP-independent receptor protein mutant (CRP*141 gln) were examined by using Raman spectroscopy. Spectra were obtained from CRP and CRP*141 gln dissolved in 0.3 M NaCl and 30 mM sodium phosphate at protein concentrations of 30-40 mg/mL. CRP and CRP.cAMP1 were compared at lower protein concentrations (10-12 mg/mL) in a solvent of 0.35 M NaCl and 20 mM sodium phosphate. Raman analysis indicates that CRP structural changes induced by one bound cAMP or by the Gly to Gln mutation at residue 141 are small. Spectra of the three CRP samples are essentially identical from 400 to 1900 cm-1. This result differs from the Raman spectroscopy study of CRP and CRP.cAMP2 cocrystals [DeGrazia et al. (1990) Biochemistry 29, 3557]. The latter work showed spectral differences between CRP and CRP.cAMP2 consistent with alterations in the protein conformation. These studies indicate that CRP and CRP.cAMP1 in solution are similar in structure and differ from CRP.cAMP2 cocrystals. Protease digestion and a DNA binding assay were also employed to characterize the wild-type and mutant proteins. CRP*141 gln exhibited the same conformational characteristics of previously reported cAMP-independent mutant proteins. It was sensitive to proteolytic attack in the absence of cAMP, or upon addition of cGMP. In the absence of cAMP, both wild-type and mutant CRPs bound noncooperatively to a 62 bp lac promoter DNA. The equilibrium constants were approximately 10(6) M-1 in 0.1 M Na+. CRP*141 gln had a 2-4-fold higher affinity for the 62 bp DNA than CRP.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of base-pair sequence on the conformations and thermally induced transitions in oligodeoxyribonucleotides containing only AT base pairs

Tm curves, CD spectra, and kinetics results of the self-complementary DNA dodecamers d(A6T6), d(A3T3A3T3), d(A2T2A2T2A2T2), d(ATATATATATAT), and d(T6A6) demonstrate that the thermal transitions of these oligomers at low salt concentration involve a hairpin intermediate. At high salt concentrations (greater than 0.1 M Na+) only a duplex to denatured-strand transition appears to occur. The temperature and salt-concentration regions of the transitions are very sequence dependent. Alternating-type AT sequences have a lower duplex stability and a greater tendency to form hairpins than sequences containing more nonalternating AT base pairs. Of the two nonalternating sequences, d(T6A6) is significantly less stable than d(A6T6). Both oligomers have CD curves that are very similar to the unusual CD spectrum of poly(dA).poly(dT). The Raman spectra of these two oligomers are also quite similar, but at low temperature, small intensity differences in two backbone modes and three nucleoside vibrations are obtained. The hairpin to duplex transition for the AT dodecamers was examined by salt-jump kinetics measurements. The transition is faster than transitions for palindromic-sequence oligomers containing terminal GC base pairs. Stopped-flow kinetics studies indicate that the transition is second order and has a relatively low activation energy. The reaction rate increases with increasing ionic strength. These results are consistent with a three-step mechanism for the hairpin to duplex reaction: (i) fraying of the hairpin oligomers' terminal base pairs, (ii) a rate-determining bimolecular step involving formation of a cruciform-type intermediate from two hairpin oligomers with open terminal base pairs, and (iii) base-pair migration and formation in the intermediate to give the duplex.

Investigation of the cAMP receptor protein secondary structure by Raman spectroscopy

Raman spectroscopy was employed to examine the secondary structure of the cAMP receptor protein (CRP). Spectra were obtained over the range 400-1900 cm-1 from solutions of CRP and from CRP-cAMP cocrystals. The spectra of CRP dissolved in 30 mM sodium phosphate and 0.15 M NaCl buffered at either pH 6 or pH 8 or dissolved in 0.15-0.2 M NaCl at protein concentrations of 5, 15, and 30 mg/mL were examined. Estimates of the secondary structure distribution were made by analyzing the amide I region of the spectra (1630-1700 cm-1). CRP secondary structure distributions were essentially the same in either pH and at all protein concentrations examined. The amide I analyses indicated a structural distribution of 44% alpha-helix, 28% beta-strand, 18% turn, and 10% undefined for CRP in solution. Raman spectra of CRP-cAMP cocrystals differed from the spectra of CRP in solution. Some differences were assigned to interfering background bands, whereas other spectral differences were attributed to changes in CRP structure. Differences in the amide III region and in the intensity at 935 cm-1 were consistent with alterations in secondary structure. Analysis of the amide I region of the CRP-cAMP cocrystal spectrum indicated a secondary structure distribution of 37% alpha-helix, 33% beta-strand, 17% turn, and 12% undefined. This result is in agreement with a published secondary structure distribution derived from X-ray analysis of CRP-cAMP cocrystals (37% alpha-helix and 36% beta-strand).(ABSTRACT TRUNCATED AT 250 WORDS)

Solubilities of trace copper and lead species and the complexing capacity of river water in the Linggi River Basin

Chemical forms of copper and lead in river water of the Linggi River Basin have been fractionated into ASV labile, moderately labile, slowly labile, and inert metal species, based on a previously proposed scheme. Free (hydrated) metal ions were identified by a potentiometric method using an ion selective electrode. Speciation results showed that the soluble copper and lead species occurred mainly in the moderately labile and slowly labile fractions. The speciation results are primarily interpreted in terms of organic interaction due to agricultural based and light industries, and urban discharges. The measured metal complexing capacity (MCC) of the samples reveals consistency of the results with the nature of the discharge. MCC correlates reasonably well with the value from the permanganate test on the river water. In general, the speciation pattern was found to be consistent with the findings of other workers.