Sirisha Senthil

Retinal nerve fiber layer and macular inner retina measurements by spectral domain optical coherence tomograph in Indian eyes with early glaucoma

PurposeTo compare the diagnostic abilities of peripapillary retinal nerve fiber layer (RNFL) and macular inner retina (MIR) measurements by spectral domain optical coherence tomography (SD–OCT) in Indian eyes early glaucoma.MethodsIn an observational, cross-sectional study, 125 eyes of 64 normal subjects and 91 eyes of 59 early glaucoma patients underwent RNFL and MIR imaging with SD–OCT. Glaucomatous eyes had characteristic optic nerve and RNFL abnormalities and correlating visual field defects and a mean deviation of better than or equal to -6 dB on standard automated perimetry. Areas under the receiver operating characteristic curves (AUC), sensitivities at a fixed specificity and likelihood ratios (LRs) were estimated for all RNFL and MIR parameters.ResultsThe AUCs for the RNFL parameters ranged from 0.537 for the temporal quadrant thickness to 0.821 for the inferior quadrant RNFL thickness. AUCs for the MIR parameters ranged from 0.603 for the superior minus inferior MIR thickness average to 0.908 for ganglion cell complex focal loss volume (GCC–FLV). AUC for the best MIR parameter (GCC–FLV) was significantly better (P<0.001) than that of the best RNFL parameter (inferior quadrant thickness). The sensitivities of these parameters at high specificity of 95%, however, were comparable (52.7% vs58.2%). Evaluation of the LRs showed that outside normal limits results of most of the RNFL and MIR parameters were associated with large effects on the post-test probability of disease.ConclusionMIR parameters with RTVue SD–OCT were as good as the RNFL parameters to detect early glaucoma.

Predictors of normal optic nerve head, retinal nerve fiber layer, and macular parameters measured by spectral domain optical coherence tomography.

PURPOSE To evaluate the effects of signal strength, age, sex, optic disc size, and axial length on the normal optic nerve head (ONH), retinal nerve fiber layer (RNFL), and macular measurements with spectral domain optical coherence tomography (SD-OCT). METHODS In an observational, cross-sectional study, 119 eyes of 60 normal subjects of Indian origin underwent ONH, RNFL, and macular imaging with SD-OCT during the same visit. Linear mixed-modeling methods were used to evaluate the effects of signal strength, age, sex, optic disc area, and axial length on ONH, RNFL, and macular measurements. RESULTS ONH rim measurements increased and cup measurements decreased with increasing signal strengths. For a 10-unit increase in signal strength, total rim area increased by a mean of 0.1 mm(2). ONH measurements also increased with increasing optic disc size. Rim measurements decreased and cup measurements increased with increasing axial length. None of the predictors influenced RNFL measurements. Macular inner retinal thickness decreased by a mean of 1.7 μm and macular full retinal thickness decreased by an average of 3.4 μm for every decades increase in age. Sex did not influence any of the measurements. CONCLUSIONS Signal strength, optic disc size, and axial length had a significant effect on ONH measurements, whereas age had a significant effect on macular measurements. None of the predictors evaluated influenced the RNFL measurements. These predictors should be considered when evaluating change in the structural measurements in glaucoma over time.

Effect of Spectrum Bias on the Diagnostic Accuracy of Spectral-Domain Optical Coherence Tomography in Glaucoma

PURPOSE To evaluate the influence of a control group on the diagnostic accuracy of spectral-domain optical coherence tomography (SD-OCT) in early glaucoma. METHODS In a diagnostic, case-control study, 119 eyes of 60 normal subjects with no findings suspicious for glaucoma (control cohort 1); 76 eyes of 41 subjects referred by general ophthalmologists as glaucoma suspects based on optic disc morphology, but found by glaucoma experts to be normal but with physiological variations in their optic nerves (control cohort 2); and 65 eyes of 46 early-glaucoma patients (cases) underwent imaging of the optic nerve head (ONH), retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) by SD-OCT. RESULTS Areas under the receiver operating characteristic curves (AUC) of ONH parameters discriminating glaucomatous eyes from normal eyes of control cohort 2 were significantly lesser (P < 0.001) than those discriminating glaucomatous eyes from normal eyes of control cohort 1. AUCs of RNFL parameters discriminating glaucomatous eyes from normal eyes of control cohorts 2 and 1 were comparable. Although the AUCs of GCC thickness parameters were comparable, AUCs of GCC focal and global loss volume in control cohort 2 (0.684 and 0.671. respectively) were significantly less (P < 0.05) than in control cohort 1 (0.881 and 0.841, respectively). CONCLUSIONS The effectiveness of most SD-OCT parameters in detecting glaucoma significantly decreased when evaluated against a clinically relevant control group with suspicious-looking optic nerves compared with that against a control group consisting of normal subjects with no findings suspicious for glaucoma.

Prevalence and Risk Factors for Primary Glaucomas in Adult Urban and Rural Populations in the Andhra Pradesh Eye Disease Study

PURPOSE To compare the prevalence of and risk factors for primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG) in urban and rural populations in the Andhra Pradesh Eye Disease Study. DESIGN A population-based, cross-sectional study using a stratified, random, cluster, and systematic sampling strategy. PARTICIPANTS Between 1996 and 2000, participants from 94 clusters in 1 urban and 3 rural areas representative of the population were included. METHODS We performed a detailed eye examination, including applanation tonometry, gonioscopy, and dilated fundus evaluation after ruling out risk of angle closure. Humphrey threshold 24-2 visual fields were performed when indicated. MAIN OUTCOME MEASURES Glaucoma was diagnosed and categorized using International Society of Geographical and Epidemiological Ophthalmology criteria. The prevalence and risk factors for POAG and PACG in subjects aged > or = 40 years were compared between the urban and rural cohorts. RESULTS There were 3724 subjects > or = 40 years, with 934 in the urban and 2790 in the rural cohort. The prevalence of POAG was greater in the urban compared with the rural cohort (4% vs 1.6%; P<0.001). Age and intraocular pressure (IOP) were risk factors for POAG in both cohorts. Blindness owing to POAG was 11.1% in the rural and 2.7% in the urban cohort. The prevalence of PACG (1.8% vs 0.7%; P<0.01), primary angle closure (PAC) (0.8% vs 0.2%; P = 0.02) and primary angle closure suspect (PACS; 3.5% vs 1.5%; P<0.01) were significantly different between the urban and rural cohorts. Increasing age was a risk factor in the urban cohort. Intraocular pressure was a risk factor in both the populations. Blindness owing to PACG was equal (20%) in both the populations. Female gender was a risk factor in the rural cohort (P = 0.032). CONCLUSIONS The prevalence of both POAG and PACG was greater in urban than in the rural population. Intraocular pressure was a significant risk factor for both POAG and PACG in both cohorts. Increasing age was a significant risk factor for POAG in both cohorts and for PACG in the urban cohort. Female gender was a risk factor for PACG in the rural cohort. There was more blindness owing to PACG than to POAG. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Angle Closure in the Andhra Pradesh Eye Disease Study

OBJECTIVE To estimate the prevalence and associated risk factors for primary angle-closure glaucoma (PACG), primary angle closure (PAC), and primary angle-closure suspects (PACS) in the Indian state of Andhra Pradesh. DESIGN A population-based, cross-sectional study using a stratified, random, cluster, and systematic sampling strategy. PARTICIPANTS Between 1996 and 2000, participants aged > or =40 years from 94 clusters in 1 urban and 3 rural areas were included. METHODS Trained professionals performed a detailed eye examination, including visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, and dilated fundus evaluation after ruling out risk of angle closure. Humphrey threshold 24-2 visual fields (VFs) were performed when indicated by disc criteria or if intraocular pressure (IOP) was > or =22 mmHg. MAIN OUTCOME MEASURES Angle closure was diagnosed and categorized using International Society of Geographical and Epidemiological Ophthalmology criteria. RESULTS Primary angle-closure glaucoma was present in 35 of 3724 subjects aged > or =40 years, an age- and gender-adjusted prevalence of 0.94% (95% confidence interval [CI], 0.63-1.24). Primary angle closure was present in 12 subjects (0.3%; 95% CI, 0.1-0.5), and PACS was present in 71 subjects (2%; 95% CI, 1.5-2.3). The prevalence of angle-closure disease (ACD=PACG+PAC) was 1.26% (95% CI, 0.90-1.62). Forty-one of 47 subjects (87.2%) with ACD were unaware of their disease. The prevalence of PACG increased from 0.56% (0.17-0.94) in the fourth decade to 2.5% (0.87-4.12) in the seventh decade. Seven (20%) of the 35 subjects with PACG were blind (visual acuity <3/60). Intraocular pressure increase (odds ratio [OR] 1.16; 95% CI, 1.11-1.22; P<0.001), diabetes mellitus (OR 3.18l; 95% CI, 1.34-7.58; P=0.001), and female gender (OR 2.07; 95% CI, 1.09-3.93; P=0.025) were significantly associated with angle-closure disease. No significant association was found with systemic hypertension (P=0.24) and hyperopia (P=0.05). CONCLUSIONS The prevalence of PACG in this population was 0.94%. Increasing age, increasing IOP, diabetes mellitus, and female gender were significantly associated with angle-closure disease. Blindness due to PACG was 20%.

Ability of different scanning protocols of spectral domain optical coherence tomography to diagnose preperimetric glaucoma.

PURPOSE To evaluate the ability of the optic nerve head (ONH), retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) parameters of spectral domain optical coherence tomograph (SDOCT) in detecting preperimetric glaucoma. METHODS In a cross-sectional study, 34 preperimetric glaucoma eyes (34 patients) and 72 control eyes (72 subjects) with large physiologic optic disc cupping underwent ONH, RNFL, and GCC imaging with SDOCT. Preperimetric glaucoma was diagnosed in the presence of glaucomatous optic neuropathy on masked evaluation of optic disc photographs by two glaucoma experts and normal visual fields. The ability of SDOCT parameters to discriminate preperimetric glaucoma eyes from eyes with large physiologic cups was evaluated by areas under the receiver operating characteristic curves (AUC), sensitivities at fixed specificities, and likelihood ratios (LR). RESULTS All SDOCT parameters were significantly different (P < 0.05) between the two groups. The ONH, RNFL, and GCC parameters with best AUCs to differentiate preperimetric glaucoma from eyes with large physiologic cups were vertical cup to disc ratio (0.76), inferior quadrant RNFL thickness (0.76), and inferior quadrant GCC thickness (0.75), respectively. Sensitivities at 95% specificity of SDOCT parameters ranged between 15% and 29%. Likelihood ratios of outside normal limits category of parameters ranged between 3 and 11, and within normal limits category between 0.5 and 0.8. CONCLUSIONS Diagnostic abilities of ONH, RNFL, and GCC parameters of SDOCT to differentiate preperimetric glaucoma eyes from control eyes with large physiologic cupping were only moderate.

Relationship between Severity of Visual Field Loss at Presentation and Rate of Visual Field Progression in Glaucoma

PURPOSE To evaluate the relationship between severity of visual field (VF) loss at presentation and rate of VF progression in glaucoma. DESIGN Clinic-based, retrospective study. PARTICIPANTS We included 512 eyes of 310 primary glaucoma patients. METHODS We analyzed the VFs of all subjects of primary glaucoma who had >5 VFs between 1989 and 2008. Based on the mean deviation (MD), we classified the VF loss as mild (MD > -6 dB), moderate (MD ≤ -6 to ≥ -12 dB) or severe (MD < -12 dB). Guided Progression Analysis software which gives the rate of progression (ROP) of Visual Field Index per year was used to assess the ROP. MAIN OUTCOME MEASURES Relationship between severity of VF loss at presentation and ROP. RESULTS The median duration of follow-up was 6.8 years. The ROP increased (worsened) by 0.02% per year for every dB worsening of MD (P = 0.02) and for every year of increasing age (P = 0.001). Association between MD and ROP showed a significant positive relationship in mild (β = 0.18; P = 0.001) and a significant negative relationship in severe (β = -0.16; P<0.001) VF loss category. Association between MD and ROP was not significant in the moderate VF loss category (β = -0.05; P = 0.61). CONCLUSIONS In early stages of glaucoma, the ROP worsened as the severity increased, but, in later stages of the disease, ROP became smaller as the severity increased. There is a need for better methods to detect progression in eyes with severe glaucomatous damage.

Comparison of outcomes of trabeculectomy with mitomycin C vs. ologen implant in primary glaucoma

Purpose: To compare the safety and efficacy of trabeculectomy with Ologen implant vs. trabeculectomy with Mitomycin C (MMC). Materials and Methods: In a prospective, randomized, pilot study, 39 eyes of 33 subjects with medically uncontrolled primary glaucoma, aged 18 years or above underwent trabeculectomy either with MMC (20 eyes) or with Ologen implant (19 eyes). The primary outcome measure was cumulative success probability, defined as complete if the intraocular pressure (IOP) was > 5 and ≤ 21 mm Hg without anti-glaucoma medications or additional surgery and qualified if an IOP was > 5 and ≤ 21 mm Hg with or without anti-glaucoma medications. Results: Mean (± standard deviation) follow-up in Ologen group was 19.1 ± 8.1 months, and in MMC group was 18.0 ± 8.4 months. Mean IOP reduction at 6 months was significantly lower (P = 0.01) in the MMC group (11.9 ± 2.9 mm Hg) as compared to Ologen group (14.6 ± 2.7 mm Hg). However, at 12 months (P = 0.81) and 24 months (P = 0.32), the mean IOP was similar between the 2 groups. Complete success probability at the end of 6 months in Ologen group was 100% (95% confidence interval: 59.1 - 99.0) was similar (P = 0.53) to that in MMC group (93.8%, 95% CI: 63.2 - 99.1). The incidences of early post-operative complications were similar in the 2 groups, except hyphema, which was significantly more in Ologen group (P = 0.02). Conclusion: In this pilot study, the success of trabeculectomy and complications were similar in both Ologen and MMC groups at the end of 6 months.

Evaluation of central corneal thickness measurement with RTVue spectral domain optical coherence tomography in normal subjects.

Purpose: To determine (1) repeatability of central corneal thickness (CCT) measurements by spectral domain optical coherence tomography (RTVue; Optovue, Inc, Fremont, CA) and (2) agreement between CCT measurements by RTVue and those by ultrasonic pachymetry, Orbscan, and anterior segment optical coherence tomography (ASOCT). Methods: In a prospective observational study, 2 cohorts of normal subjects were recruited. In the first cohort (51 subjects), 5 measurements of CCT were obtained by RTVue during the same visit to determine the repeatability. In the second cohort (65 subjects), CCT measurements were obtained by RTVue, ultrasonic pachymetry, Orbscan, and ASOCT during the same visit to determine the agreement among these instruments. Repeatability was assessed by intraclass correlation coefficient (ICC), within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation. Agreement was assessed by ICC and Bland and Altman plots. Results: Repeatability of CCT measurements by RTVue as assessed by ICC, within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation was 0.99 (0.99-0.99), 2.2 (1.9-2.5), 4.2 μm (3.6-4.8), and 0.4% (0.3-0.5), respectively. The average CCT by RTVue (529 μm) was comparable to that by ultrasonic pachymetry (539 μm; P = 0.15), Orbscan (536 μm; P = 0.54), and ASOCT (526 μm; P = 0.77). The 95% limits of agreement on Bland and Altman plots ranged from 20 μm (between RTVue and ASOCT) to 33 μm (between RTVue and Orbscan). Conclusions: CCT measurements by RTVue have an excellent repeatability. Although CCT measurements by RTVue are comparable to that by ultrasonic pachymetry, Orbscan, and ASOCT, the difference between instruments can be significant depending on the clinical situation considered.

Treatment outcomes in malignant glaucoma.

PURPOSE To report treatment outcomes in malignant glaucoma. DESIGN Retrospective case series. PARTICIPANTS Twenty-eight eyes of 26 patients who were treated for malignant glaucoma between 1991 and 2009. METHODS Malignant glaucoma was diagnosed based on the presence of a shallow or flat central and peripheral anterior chamber in the presence of patent iridotomy, with intraocular pressure (IOP) of 22 mmHg or more after any intraocular surgery. The treatment algorithm included antiglaucoma medications and cycloplegics as first-line methods; the second-line therapy in pseudophakic eyes was laser hyaloidotomy, followed by vitrectomy-hyaloidotomy-iridectomy (VHI) or transscleral cyclophotocoagulation (TSCPC). MAIN OUTCOME MEASURES Resolution was defined as deepening of the central anterior chamber and IOP of 21 mmHg or less (on 2 successive follow-ups at least 1 week apart) with or without topical antiglaucoma medications in the absence of systemic antiglaucoma medications. RESULTS At the diagnosis of malignant glaucoma, 5 eyes were phakic and 23 were pseudophakic. The preceding surgeries were trabeculectomy (11 eyes), cataract surgery (10 eyes), and combined cataract and glaucoma surgery (7 eyes). Mean IOP decreased from 34 ± 8.3 mmHg at presentation to 14.3 ± 5.2 mmHg at the last visit (P<0.001). Resolution of malignant glaucoma was seen in 27 eyes (27/28; 96%), 17 eyes resolved with 1 intervention, and 10 eyes required repeat procedures. Of the 27 eyes whose disease resolved, this result was achieved in 4 eyes with medical treatment, in 7 pseudophakic eyes with laser hyaloidotomy, in 4 eyes with VHI, and in 12 eyes with TSCPC. The median duration of follow-up was 192 days (interquartile range, 35-425 days). There was no difference in the visual acuity at presentation and at the final visit in 14 eyes. Eight eyes gained 2 lines or more and 6 eyes lost 2 lines or more of visual acuity. CONCLUSIONS Malignant glaucoma can be managed successfully by appropriate and timely interventions. Medical treatment was beneficial in phakic eyes, laser hyaloidotomy was beneficial in pseudophakic eyes, and vitrectomy and TSCPC were beneficial in refractory cases. A stepladder approach to treatment was successful (96%) in this series. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.