Vikas Chopra

Detection of Macular Ganglion Cell Loss in Glaucoma by Fourier-Domain Optical Coherence Tomography

PURPOSE To map ganglion cell complex (GCC) thickness with high-speed Fourier-domain optical coherence tomography (FD-OCT) and compute novel macular parameters for glaucoma diagnosis. DESIGN Observational, cross-sectional study. PARTICIPANTS One hundred seventy-eight participants in the Advanced Imaging for Glaucoma Study, divided into 3 groups: 65 persons in the normal group, 78 in the perimetric glaucoma group (PG), and 52 in the preperimetric glaucoma group (PPG). METHODS The RTVue FD-OCT system was used to map the macula over a 7 x 6 mm region. The macular OCT images were exported for automatic segmentation using software we developed. The program measured macular retinal (MR) thickness and GCC thickness. The GCC was defined as the combination of nerve fiber, ganglion cell, and inner plexiform layers. Pattern analysis was applied to the GCC map and the diagnostic powers of pattern-based diagnostic parameters were investigated. Results were compared with time-domain (TD) Stratus OCT measurements of MR and circumpapillary nerve fiber layer (NFL) thickness. MAIN OUTCOME MEASURES Repeatability was assessed by intraclass correlation, pooled standard deviation, and coefficient of variation. Diagnostic power was assessed by the area under the receiver operator characteristic (AROC) curve. Measurements in the PG group were the primary measures of performance. RESULTS The FD-OCT measurements of MR and GCC averages had significantly better repeatability than TD-OCT measurements of MR and NFL averages. The FD-OCT GCC average had significantly (P = 0.02) higher diagnostic power (AROC = 0.90) than MR (AROC = 0.85 for both FD-OCT and TD-OCT) in differentiating between PG and normal. One GCC pattern parameter, global loss volume, had significantly higher AROC (0.92) than the overall average (P = 0.01). The diagnostic powers of the best GCC parameters were statistically equal to TD-OCT NFL average. CONCLUSIONS The higher speed and resolution of FD-OCT improved the repeatability of macular imaging compared with standard TD-OCT. Ganglion cell mapping and pattern analysis improved diagnostic power. The improved diagnostic power of macular GCC imaging is on par with, and complementary to, peripapillary NFL imaging. Macular imaging with FD-OCT is a useful method for glaucoma diagnosis and has potential for tracking glaucoma progression.

Baseline Risk Factors that Predict the Development of Open-Angle Glaucoma in a Population: The Los Angeles Latino Eye Study

OBJECTIVE To determine which baseline sociodemographic, lifestyle, anthropometric, clinical, and ocular risk factors predict the development of open-angle glaucoma (OAG) in an adult population. DESIGN A population-based, prospective cohort study. PARTICIPANTS A total of 3772 self-identified Latinos aged ≥40 years from Los Angeles, California, who were free of OAG at baseline. METHODS Participants from the Los Angeles Latino Eye Study had standardized study visits at baseline and 4-year follow-up with structured interviews and a comprehensive ophthalmologic examination. We defined OAG as the presence of an open angle and a glaucomatous visual field abnormality and/or evidence of glaucomatous optic nerve damage in ≥1 eye. Multivariate logistic regression with stepwise selection was performed to determine which potential baseline risk factors independently predict the development of OAG. MAIN OUTCOME MEASURES Odds ratios for various risk factors. RESULTS Over the 4-year follow-up, 87 participants developed OAG. The baseline risk factors that predict the development of OAG include older age (odds ratio [OR] per decade, 2.19; 95% confidence interval [CI], 1.74-2.75; P<0.001), higher intraocular pressure (IOP; OR per mmHg, 1.18; 95% CI, 1.10-1.26; P<0.001), longer axial length (OR per mm, 1.48; 95% CI, 1.22-1.80; P<0.001), thinner central cornea (OR per 40 μm thinner, 1.30; 95% CI, 1.00-1.70; P = 0.050), higher waist-to-hip ratio (OR per 0.05 higher, 1.21; 95% CI, 1.05-1.39; P = 0.007) and lack of vision insurance (OR, 2.08; 95% CI, 1.26-3.41; P = 0.004). CONCLUSIONS Despite a mean baseline IOP of 14 mmHg in Latinos, higher IOP is an important risk factor for developing OAG. Biometric measures suggestive of less structural support such as longer axial length and thin central corneal thickness were identified as important risk factors. Lack of health insurance reduces access to eye care and increases the burden of OAG by reducing the likelihood of early detection and treatment of OAG. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Intraocular Pressure, Central Corneal Thickness, and Prevalence of Open-Angle Glaucoma: The Los Angeles Latino Eye Study

PURPOSE To examine the relationship between the prevalence of open-angle glaucoma (OAG) and intraocular pressure (IOP) and the impact of central corneal thickness (CCT) on this relationship. DESIGN Population-based cross-sectional study. METHODS The study cohort consisted of 5,970 participants from the Los Angeles Latino Eye Study (LALES) with no history of glaucoma treatment and with complete ophthalmic examination data. The relationship between the prevalence of OAG and IOP was contrasted across persons with CCT designated as thin, normal, or thick. RESULTS Prevalence of OAG was exponentially related to IOP. When stratified by CCT, persons with thin CCT had a significantly higher prevalence of OAG than did those with normal or thick CCTs at all levels of IOP. Adjusting each IOP individually for CCT did not impact significantly the relationship between the prevalence of OAG and IOP. CONCLUSIONS These findings suggest that adjusting for the impact of CCT on IOP by correction algorithms is not necessary in a population based assessment of glaucoma prevalence; CCT, however, is an important independent risk factor for the prevalence of OAG.

Regional Correlation Among Ganglion Cell Complex, Nerve Fiber Layer, and Visual Field Loss in Glaucoma

PURPOSE To analyze the relationship among macular ganglion cell complex (GCC) thickness, peripapillary nerve fiber layer (NFL) thickness, and visual field (VF) defects in patients with glaucoma. METHODS A Fourier-domain optical coherence tomography (FD-OCT) system was used to map the macula and peripapillary regions of the retina in 56 eyes of 38 patients with perimetric glaucoma. The macular GCC and peripapillary NFL thicknesses were mapped and standard automated perimetry (SAP) was performed. Loss of GCC and NFL were correlated with the VF map on both a point-by-point and regional basis. RESULTS Correlation between GCC thickness and peripapillary NFL thickness produced a detailed correspondence map that demonstrates the arcuate course of the NFL in the macula. Corresponding regions within the GCC, NFL, and VF maps demonstrate significant correlation, once parafoveal retinal ganglion cell (RGC) displacement is taken into account. CONCLUSIONS There are significant point-specific and regional correlations between GCC loss, NFL loss, and deficits on SAP. Using these different data sources together may improve our understanding of glaucomatous damage and aid in the management of patients with glaucoma.

Postoperative Complications in the Ahmed Baerveldt Comparison Study During Five Years of Follow-up

PURPOSE To compare the late complications in the Ahmed Baerveldt Comparison Study during 5 years of follow-up. DESIGN Multicenter, prospective randomized clinical trial. METHODS setting: Sixteen international clinical centers. STUDY POPULATION Two hundred seventy-six subjects aged 18-85 years with previous intraocular surgery or refractory glaucoma with intraocular pressure of >18 mm Hg. INTERVENTIONS Ahmed Glaucoma Valve FP7 or Baerveldt Glaucoma Implant BG 101-350. MAIN OUTCOME MEASURES Late postoperative complications (beyond 3 months), reoperations for complications, and decreased vision from complications. RESULTS Late complications developed in 56 subjects (46.8 ± 4.8 5-year cumulative % ± SE) in the Ahmed Glaucoma Valve group and 67 (56.3 ± 4.7 5-year cumulative % ± SE) in the Baerveldt Glaucoma Implant group (P = .082). The cumulative rates of serious complications were 15.9% and 24.7% in the Ahmed Glaucoma Valve and Baerveldt Glaucoma Implant groups, respectively (P = .034), although this was largely driven by subjects who had tube occlusions in the 2 groups (0.8% in the Ahmed Glaucoma Valve group and 5.7% in the Baerveldt Glaucoma Implant group, P = .037). Both groups had a relatively high incidence of persistent diplopia (12%) and corneal edema (20%), although half of the corneal edema cases were likely due to pre-existing causes other than the aqueous shunt. The incidence of tube erosion was 1% and 3% in the Ahmed Glaucoma Valve and Baerveldt Glaucoma Implant groups, respectively (P = .04). CONCLUSIONS Long-term rates of vision-threatening complications and complications resulting in reoperation were higher in the Baerveldt Glaucoma Implant than in the Ahmed Glaucoma Valve group over 5 years of follow-up.

Four-year incidence of Open-angle Glaucoma and Ocular Hypertension: The Los Angeles Latino Eye Study

PURPOSE To estimate the 4-year incidence of open-angle glaucoma (OAG) and ocular hypertension (OHT) among adult Latinos 40 years of age and older. DESIGN Population-based longitudinal study. METHODS Comprehensive ophthalmologic examinations including intraocular pressure, visual field testing, and stereoscopic fundus photography were performed at both baseline and the 4-year follow-up examination. Incident OAG at the 4-year follow-up examination was defined as the presence of an open angle and a glaucomatous visual field abnormality or evidence of glaucomatous optic disc damage, or both when not present at baseline. Incident OHT was defined as intraocular pressure of more than 21 mm Hg and the absence of optic disc damage or abnormal visual field results at the 4 year follow-up examination when not present at baseline. RESULTS Among the 3939 participants (mean age, 54.7 ± 10.5 years) with complete data for a diagnosis of glaucoma at both baseline and follow-up examination, incident OAG at the 4-year follow-up was identified in 87 persons (4-year incidence rate, 2.3%; 95% confidence interval, 1.8% to 2.8%). Incident OHT at the 4-year follow-up was identified in 124 persons (4-year incidence rate, 3.5%; 95% confidence interval, 2.9% to 4.1%). In participants with OAG in 1 eye, the 4-year risk of OAG developing in the fellow eye was 5 times as high as the risk for those without OAG in either eye at baseline. In participants with OHT in 1 eye, the 4-year risk of OHT developing in the fellow eye was 10 times as high as the risk for those without OHT in either eye at baseline. The incidence rates of OAG and OHT were higher in older Latinos than in younger Latinos. CONCLUSIONS Incidence of OAG in Latinos is higher than in non-Hispanic whites, but lower than in Afro-Caribbeans. The relatively high rate of incident OAG and OHT underscores the need for community screening programs in this fastest growing segment of the United States population.

Does Optic Nerve Head Size Variation Affect Circumpapillary Retinal Nerve Fiber Layer Thickness Measurement by Optical Coherence Tomography

PURPOSE To determine the relationship between retinal nerve fiber layer (RNFL) thickness, optic disc size, and image magnification. METHODS The cohort consisted of 196 normal eyes of 101 participants in the Advanced Imaging for Glaucoma Study (AIGS), a multicenter, prospective, longitudinal study to develop advanced imaging technologies for glaucoma diagnosis. Scanning laser tomography was used to measure disc size. Optical coherence tomography (OCT) was used to perform circumpapillary RNFL thickness measurements using the standard fixed 3.46-mm nominal scan diameter. A theoretical model of magnification effects was developed to relate RNFL thickness (overall average) with axial length and magnification. RESULTS Multivariate regression showed no significant correlation between RNFL thickness and optic disc area (95% confidence interval [CI] = -0.9 to 4.1 μm/mm², P = 0.21). Linear regression showed that RNFL thickness depended significantly on axial length (slope = -3.1 μm/mm, 95% CI = -4.9 to -1.3, P = 0.001) and age (slope = -0.3 μm/y, 95% CI = -0.5 to -0.2, P = 0.0002). The slope values agreed closely with the values predicted by the magnification model. CONCLUSIONS There is no significant association between RNFL thickness and optic disc area. Previous publications that showed such an association may have been biased by the effect of axial length on fundus image magnification and, therefore, both measured RNFL thickness and apparent disc area. The true diameter of the circumpapillary OCT scan is larger for a longer eye (more myopic eye), leading to a thinner RNFL measurement. Adjustment of measured RNFL thickness by axial length, in addition to age, may lead to a tighter normative range and improve the detection of RNFL thinning due to glaucoma.

Endoscopic cyclophotocoagulation (ECP) in the management of uncontrolled glaucoma with prior aqueous tube shunt.

PurposeTo evaluate the efficacy and safety of endoscopic cyclophotocoagulation (ECP) in the treatment of uncontrolled glaucoma with a prior aqueous tube shunt. MethodsA prospective, nonrandomized, interventional clinical trial with up to 2 years of follow up included 25 eyes of 25 consecutive glaucoma patients with a previous tube shunt and uncontrolled intraocular pressure (IOP) despite medical therapy. Patients had IOP greater than 21 mm Hg on maximal medications or IOP ⩽21 mm Hg but intolerant to medications or using an oral carbonic anhydrase inhibitor. Application of ECP over 360 degrees was performed and subjects were followed for 6 months minimum. Main outcome measures were mean reduction in IOP and medications at 12 months. Success was defined as reduction in IOP of 3 mm Hg and discontinuation of nontolerated glaucoma medications. A failure was defined as continued uncontrolled IOP, vision loss to no light perception, or additional medications or glaucoma surgery required. ResultsAt 12 months, the mean IOP dropped from 24.02 to 15.36 mm Hg. The mean of the differences was −7.77 mm Hg (−30.8%). The mean number of medications was 3.2 before laser and 1.5 at 12 months (P<0.001). The success rate at 12 months (n=18) was 88% and remained at that level until the end of the follow-up period of 2 years (n=11, P<0.00005). There were no serious complications. ConclusionsECP seems to be a safe and effective treatment in patients with uncontrolled IOP with a prior aqueous tube shunt, and is a reasonable option in this group of refractory glaucoma patients.

Retinal vessel density from optical coherence tomography angiography to differentiate early glaucoma, pre-perimetric glaucoma and normal eyes

Purpose To evaluate optic nerve vascular density using swept source optical coherence tomography angiography (OCTA) in patients with early primary open angle glaucoma (POAG), pre-perimetric glaucoma and normal eyes. Methods This is a prospective, observational study including 56 eyes in total and divided into 3 groups; 20 eyes with mild POAG, 20 pre-perimetric glaucoma eyes, and 16 age-matched normal eyes as controls. The optic disc region was imaged by a 1050-nm-wavelength swept-source OCT system (DRI OCT Triton, TOPCON). Vessel density was assessed as the ratio of the area occupied by the vessels in 3 distinct regions: 1) within the optic nerve head; 2) in the 3 mm papillary region around the optic disc; and 3) in the peripapillary region, defined as a 700-μm-wide elliptical annulus around the disc. The potential associations between vessel density and structural, functional measures were analyzed. Results There was a statistically significant difference for the peripapillary vessel density, optic nerve head vessel density, and papillary vessel density among all the groups (p<0.001). Control eyes showed a significant difference for all measured vessel densities compared to glaucomatous eyes (p values from 0.001 to 0.024). There was a statistically significant difference between control and pre-perimetric glaucoma eyes for peripapillary, optic nerve head and papillary vessel density values (p values from 0.001 to 0.007). The optic nerve head vessel density, superior and inferior papillary area vessel density (Pearson r = 0.512, 0.436, 0.523 respectively) were highly correlated with mean overall, superior and inferior RNFL thickness in POAG eyes (p = 0.04, p = 0.02 and p = 0.04 respectively). Multiple linear regression analysis of POAG group showed that optic nerve head vessel density in POAG group was more strongly linked to RNFL thickness than to any other variables. Conclusions Eyes with mild POAG could be differentiated from pre-perimetric glaucoma eyes, which also could be differentiated from normal eyes using OCTA-derived retinal vessel density measurements.

Clinical Results of Ab Interno Trabeculotomy Using the Trabectome in Patients with Pigmentary Glaucoma compared to Primary Open Angle Glaucoma

To evaluate outcomes of Trabectome on pigmentary glaucoma (PG) patients compared to matched controls with primary open angle glaucoma (POAG).