Rajeev R. Pappuru

Acute macular neuroretinopathy: long-term insights revealed by multimodal imaging.

Purpose: To report the structural and functional changes in acute macular neuroretinopathy (AMN) and their long-term evolution. Multimodal retinal imaging was acquired, including Fourier domain optical coherence tomography (OCT), infrared (IR) reflectance, and near IR autofluorescence (NIA). Methods: In this retrospective observational case series, detailed clinical history and multimodal imaging are reported in eight patients with AMN. Manual segmentation of the Fourier domain OCT volume scans was done in one patient with the largest AMN lesion to yield retinal sublayer topographic maps. Results: Two patients were seen within the first 1 to 2 days of symptoms, and both showed outer nuclear and outer plexiform layer hyperreflectivity. Both patients developed enlargement of the lesion over the first week on IR reflectance imaging with a corresponding lateral extension of the outer retinal disruption on Fourier domain OCT. Thinning of the outer nuclear layer persisted in all patients with lesions >100 &mgr;m width, and in one patient this thinning worsened over the course of follow-up, as noted on the sublayer maps. This structural abnormality correlated with long-term functional deficits, persisting up to 14 months after the initial episode. Infrared reflectance highlights the lesion best, and abnormalities on near IR autofluorescence may be present. Conclusion: Acute macular neuroretinopathy acutely affects the outer nuclear and plexiform layers manifesting as OCT hyperreflectivity. The hallmark long-term changes are outer nuclear thinning on Fourier domain OCT and a fading dark lesion on IR reflectance imaging. These changes correspond to focal disruption of the outer segment/retinal pigment epithelium junction on OCT, and not the inner segment/outer segment junction, as previously reported. Optical coherence tomography and near IR autofluorescence abnormalities suggest previously unrecognized melanin and retinal pigment epithelium derangements in this condition.

Relationship between outer retinal thickness substructures and visual acuity in eyes with dry age-related macular degeneration.

PURPOSE To explore the correlation between outer retinal substructures and visual acuity in dry age-related macular degeneration (AMD). METHODS Analysis of spectral domain optical coherence tomography datasets from 100 eyes of 100 consecutive patients with dry AMD was performed. The internal limiting membrane, outer nuclear layer (ONL), external limiting membrane (ELM), inner segment-outer segment (IS-OS) junction, outer photoreceptor border, inner and outer retinal pigment epithelium (RPE) borders, and Bruchs membrane, were manually segmented by Doheny Image Reading Center (DIRC) graders. Areas, thicknesses, and volumes of RPE, IS, OS, ONL, and the total retina in the foveal central subfield were correlated with the logarithm of minimal angle of resolution (logMAR) visual acuity using univariable and multivariable regression analysis. RESULTS The visual acuity in this group ranged from logMAR 0 to 1.3 with a mean of 0.23. Areas, thicknesses, and volumes of ONL, IS and OS, thicknesses of total retinal and RPE, and intensities of IS, OS, and RPE, showed statistically significant association (P < 0.05) with logMAR best corrected visual acuity. The highest correlations were observed for the ONL (thickness: r = -0.49, volume: -0.47, area: -0.50) and photoreceptor IS (thickness: -0.59, area: -0.63, volume: -0.53). The model with the highest correlation in this study included thicknesses of ONL, IS, OS and RPE, as well as area of ONL, IS, OS, RPE, and intensity of RPE. CONCLUSIONS. Although integrity of outer retinal substructures in the foveal central subfield correlates with visual acuity in the eyes of patients with dry AMD, the correlation is only moderate and does not fully explain the variability in acuity in these cases.

Correlation between optical coherence tomography-derived assessments of lower tear meniscus parameters and clinical features of dry eye disease

Purpose: To measure the correlation between subjective symptom score, conventional clinical tests, and Fourier-domain optical coherence tomography (FD-OCT) of lower tear meniscus parameters in patients with dry eye disease. Methods: Eighteen patients with dry eye disease requiring medical therapy and/or punctal occlusion were recruited for this prospective, nonrandomized, observational case series. Severity of symptoms of dry eye disease was assessed using the Indiana University Dry Eye Questionnaire 2002. Clinical assessments were completed using slit-lamp biomicroscopy, rose bengal dye staining, fluorescein tear breakup time (TBUT), and a 5-minute Schirmer test with topical anesthesia. The lower tear meniscus was imaged using an FD-OCT system with 5-&mgr;m axial resolution and measured manually by a masked grader using computer calipers. Correlation was assessed using Spearman correlation coefficient (&rgr;). Results: The mean (±SD) scaled symptom score was 58 ± 21, with a range of 0 to 100. Vital staining test averaged 1.7 ± 3.4, TBUT averaged 4.4 ± 1.8 seconds, and Schirmer tests averaged 10.2 ± 8.1 mm. As determined by optical coherence tomography, the meniscus height was 228 ± 153 &mgr;m, depth was 127 ± 79 &mgr;m, and cross-sectional area was 0.018 ± 0.021 mm2. Optical coherence tomography meniscus area was negatively correlated with the symptom questionnaire score (P < 0.01) and positively correlated with Schirmer test results (P < 0.01). There was no significant correlation between symptom score and rose bengal staining, TBUT, or Schirmer test results (P > 0.01). Conclusions: Lower tear meniscus measurement with FD-OCT is an objective noninvasive test that correlates well with symptoms of dry eye disease and the Schirmer test.

Ultra-wide-field green-light (532-nm) autofluorescence imaging in chronic Vogt-Koyanagi-Harada disease.

BACKGROUND AND OBJECTIVE To assess the prevalence of peripheral fundus autofluorescence (FAF) abnormalities in chronic Vogt-Koyanagi-Harada disease (VKH). PATIENTS AND METHODS A retrospective review of cases at the Doheny Eye Institute between December 2009 and April 2010. Patients with chronic VKH who had ultra-wide-field FAF and pseudo-color imaging performed were included. All images were reviewed independently by two reading center certified retina specialists. RESULTS Twenty eyes of 10 patients were included in this analysis. Fourteen eyes of 7 patients (70%) showed peripheral changes on FAF images outside the posterior pole. Three different patterns were observed: multifocal hypofluorescent spots (n = 11 eyes), hyperfluorescent spots (n = 8 eyes), and a unique lattice-like pattern in both eyes of one patient. There were noticeable disparities between FAF and color images. CONCLUSION Peripheral FAF abnormalities are frequent in chronic VKH and are readily revealed by wide-field FAF imaging and manifesting with distinct patterns. Further investigation in prospective studies is warranted.

Vancomycin-resistant Gram-positive bacterial endophthalmitis: epidemiology, treatment options, and outcomes

BackgroundThe purpose of this study is to evaluate the microbiological profile and treatment outcomes of vancomycin-resistant Gram-positive bacterial endophthalmitis. Medical records of all patients with Gram-positive bacterial endophthalmitis resistant to vancomycin presenting between 1 January 2005 and 31 December 2010 were reviewed in this noncomparative, consecutive, retrospective case series. Favorable outcome was defined as a best-corrected visual acuity of ≥20/200.ResultsOut of 682 culture-positive endophthalmitis isolates, 448/682 (65.6%) were associated with Gram-positive bacteria. In vitro resistance to vancomycin was noted in 7/448 (1.56%). Three cases were posttraumatic, three were postoperative, and one was endogenous in origin. Four Bacillus isolates, two Staphylococcus isolates, and an Enterococcus isolate were resistant. Isolates resistant to vancomycin were sensitive in vitro to ciprofloxacin in 6/7 (86%) patients. Presenting visual acuity was light perception in all seven cases. Favorable outcome was achieved in only 1/7 (14.3%) cases.ConclusionsVancomycin-resistant endophthalmitis is uncommon and usually associated with poor visual outcome. Bacillus sp. is the most frequent Gram-positive bacteria resistant to vancomycin. Fluoroquinolones like ciprofloxacin may be considered as a useful alternative in vancomycin-resistant endophthalmitis.

Efficacy of anti-vascular endothelial growth factor therapy in subretinal neovascularization secondary to macular telangiectasia type 2.

Purpose: To evaluate the efficacy of intravitreal anti–vascular endothelial growth factor monotherapy in the treatment of naive subretinal neovascular membrane (SRNVM) secondary to macular telangiectasia (Mactel) Type 2. Methods: A retrospective chart review of consecutive patients with naive SRNVM secondary to Mactel who were examined between January 2007 and April 2011 was performed. Eyes with diabetic retinopathy, age-related macular degeneration, or any other macular pathology were excluded. Demographic data, medical history, and ocular history were recorded. The mean change in best-corrected visual acuity at the final visit was the primary outcome measure. The mean number of intravitreal injections, retinal thickness on optical coherence tomography, and intraocular pressure were the secondary outcomes. Results: A total of 16 eyes of 16 patients were included in the study. Of 16 eyes, 4 were treated with intravitreal ranibizumab monotherapy and 12 with intravitreal bevacizumab monotherapy. The average follow-up duration was 12 months (range, 3–43 months). The mean baseline visual acuity was 0.17 ± 0.16 (Snellen equivalent 20/120) (range, 0.001–0.5), and the mean final visual acuity was 0.27 ± 0.14 (Snellen equivalent 20/70) (range, 0.05–0.66), and this difference was statistically significant (P = 0.02). The mean number of intravitreal injections was 1.9 (range, 1–3), and there were no injection-related complications. Conclusion: Intravitreal anti–vascular endothelial growth factor monotherapy appears to be effective and safe in treatment-naive SRNVM secondary to Mactel.

Combined ceftazidime and amikacin resistance among Gram-negative isolates in acute-onset postoperative endophthalmitis: prevalence, antimicrobial susceptibilities, and visual acuity outcome

BackgroundThe purpose of this study is to evaluate the prevalence, antimicrobial susceptibilities, and visual acuity outcome of acute-onset postoperative Gram-negative bacterial endophthalmitis cases resistant to both ceftazidime and amikacin seen between 2005 and 2010 at L. V. Prasad Eye Institute, a tertiary care ophthalmic Centre in South India. Medical records of all patients with Gram-negative bacterial endophthalmitis resistant to both amikacin and ceftazidime between 1 January 2005 and 31 December 2010 were reviewed in this non-comparative, consecutive, retrospective case series. Favorable outcome was defined as a best-corrected visual acuity of ≥20/200.ResultsSixty five (39.6%) of 164 culture-positive postoperative endophthalmitis were caused by Gram-negative organisms. Among these 65 isolates, 32 (49%; 95% confidence interval (CI) 37% to 61%) were resistant to ceftazidime, 17 (26%; 95% CI 15% to 37%) to amikacin, and 12 (18.5%; 95% CI 9% to 27%) to both ceftazidime and amikacin. Eight Pseudomonas isolates, three Enterobacter isolates, and one Haemophilus isolate were resistant to both ceftazidime and amikacin. The isolates were sensitive to fluoroquinolones (42%) and imipenem (50%). Presenting visual acuity was light perception in 10 (83.3%) cases. A final visual acuity ≥20/200 was achieved in 5/12 (41.7%) of these patients.ConclusionIn the current study, Pseudomonas was the most common Gram-negative bacteria resistant to both amikacin and ceftazidime. The emergence of multidrug-resistant bacteria causing endophthalmitis is a matter of concern in India. Alternative antibiotics like imipenem or fluoroquinolones may be considered for the management of these resistant organisms.

Different phenotypes of the appearance of the outer plexiform layer on optical coherence tomography

PurposeTo present a selected case series of different phenotypes of the normal outer plexiform layer (OPL) visualized by optical coherence tomography (OCT).MethodsFive cases were selected to represent the spectrum of appearances of the OPL in this case series. Categorical descriptions of each manifestation were then developed. Additional SD-OCT scans were obtained from a normal volunteer to further support the hypothesis.ResultsThe inner one-third of the OPL typically appears hyperreflective on OCT, while the outer two-thirds (Henle fiber layer) may have a more varied appearance. Six different phenotypes of Henle fiber layer reflectivity were noted in this series, and classified as: bright, columnar, dentate, delimited, indistinct, and dark. The brightness of the Henle fiber layer appears to depend on the geometric angle between the OCT light beam and the axonal fibers in this portion of the OPL. This angle appears to be a function of the natural orientation of the Henle fiber layer tissue (θN), the existence of subretinal pathology that alters the angle of the neurosensory retina (θP), and the tilt angle of the tissue on the B-scan (θT) due to decentered OCT acquisition.ConclusionsSince accurate interpretation of the OPL/ONL boundary is of vital importance to study the thickness of ONL, location of cystoid lesions, hyperreflective crescents over drusen, et al., our case series may aid better understanding of the OPL appearance in SD-OCT. In the absence of clear delineation, it may be most correct to refer to indistinct OPL and ONL together as the photoreceptor nuclear axonal complex (PNAC).

Clinical Significance of B-Scan Averaging With SD-OCT

Averaging multiple scans is a potential advantage of optical coherence tomography. The authors evaluate the qualitative benefits of B-scan averaging on the visualization of outer retinal structures. A retrospective analysis was performed on Cirrus OCT (Carl Zeiss Meditec, Dublin, CA) B-scans from 1 eye of 35 patients referred to the imaging unit who underwent three types of scan acquisitions: no averaging, 4× averaging, and 20× averaging. Masked assessment of quality was made using a qualitative scale of 0 (worst) to 3 according to the ability to identify structure, brightness, and continuity. Quality scores consistently improved with 4× averaging, but improved only slightly further with 20×. Averaging appeared to have a statistically significant beneficial effect for the assessment of the external limiting membrane and outer nuclear layer (P < .05), with no significant benefit for visualization of the retinal pigment epithelium and inner segment/outer segment junction. The benefits of oversampling or averaging B-scans for visualizing outer retinal substructures are apparent even when averaging relatively few frames. These findings may be helpful when designing acquisition protocols in clinical trials and clinical practice.

Choroidal thickness profi le in healthy Indian subjects

Purpose: The aim was to study choroidal thickness (CT) and its profile based on location in healthy Indian subjects using Cirrus high definition (HD) optical coherence tomography. Materials and Methods: A total of 211 eyes of 115 healthy subjects with no retinal or choroidal disease were consecutively scanned using Cirrus HD 1 line raster scan mode without pupillary dilation. Eyes with any ocular disease or axial length (AXL) >24 mm or <20 mm were excluded. Experienced technician measured CT from the lower border of the retinal pigment epithelium (RPE) to the lower border of choroid. CT was measured from the posterior edge of the RPE to the choroid/sclera junction at 500-μm intervals up to 3000 μm temporal and nasal to the fovea. Generalized estimating equations were used to evaluate the correlation between CT at various locations and age, AXL, spherical equivalent, and macular thickness. Results: Mean age was 42.8 ± 13.6 years. Mean AXL was 22.84 ± 0.78 mm. Median spherical equivalent was 0.16 ± 0.64 D. Mean central macular thickness was 216.4 ± 30.03 μm. Choroidal was thinnest nasally and thickest subfoveally. On multivariate regression, age was the most significant factor affecting subfoveal CT (P = 0.000). Regression analysis showed an approximate decrease in CT of 1.18 μm every year. Conclusions: Our study provides CT profile in Indian healthy subjects in various age groups. CT depends on its location, subfoveal being the thickest and nasal being the thinnest. Age is a critical factor, which is negatively correlated with CT.