Use Of Spectral-domain Optical Coherence Tomography Research Articles

SD-OCT Imaging of Macular Changes in Fabry Disease: A Case Report

ABSTRACT Fabry disease (FD) is a rare, X-linked lysosomal storage disorder that can result in fatal end-stage renal disease, heart failure, and cerebro-occlusive events. Vague clinical symptoms and rarity often mean diagnosis and potential treatment is delayed. Ophthalmic findings in FD patients can be helpful in establishing an early diagnosis and timely treatment. Spectral domain optical coherence tomography (SD-OCT) imaging in FD patients shows hyper-reflective foci (HRF) in characteristic patterns within the inner retinal layers. We found that the HRF was localised in linear distributions at the deep and superficial borders of the retinal inner nuclear layer, likely reflecting anatomic vascular plexuses and FD-related sphingolipid deposition within the vessel walls. These results highlight the potential use of SD-OCT in FD and how it may aid diagnosis in undifferentiated patients, prognostication, and disease monitoring.

Evaluation of optic coherence tomography findings in patients with inflammatory bowel disease

BackgroundOcular complications are known to appear in inflammatory bowel disease (IBD). Among these, posterior segment complications can lead to substantial morbidity. The aim of the study is to evaluate the retinal nerve fiber layer (RNFL), ganglion cell-inner plexiform layer (GCIPL), and macula thickness measurement in patients with IBD. MethodsA total of 118 patients with IBD (42 Crohn's disease (CD), 76 ulcerative colitis (UC)) and 52 healthy subjects were included in the study. RNFL, GCIPL, and macula thickness were measured using spectral-domain optical coherence tomography (SD-OCT). ResultsThe central macular thickness was increased, mean and all superior quadrants of GCIPL thickness measurements were significantly decreased, but RNFL thickness wasn't changed in CD compared to healthy subjects. Although the central macular thickness increased, no change was observed in mean RNFL and GCIPL in UC compared to healthy subjects. Mean RNFL, GCIPL, and macular thickness did not differ during the remission and active phases of the disease in IBD. There was no difference in RNFL, GCIPL, and macular thicknesses in CD patients in terms of the location and behavior of the disease. A significant thickness increase was found in extensive type UC for inferior RNFL value compared to the left side and proctitis. ConclusionsIBD may cause an increase in macular thickness. This finding may be related to the inflammation or ischemia of the retina. The use of SD-OCT in ophthalmologic examination in patients with IBD may enable early detection of retinal changes and alert the clinician to complications of IBD.

Multifocal Electroretinogram, Central Macula Thickness and Visual Acuity in Diabetic Macular Edema Following Intravitreal Injection of anti-VEGF

Introduction : Diabetic Retinopathy (DR) is one of the major cause of visual acuity deterioration in diabetic patients. The loss of central visual acuity in diabetic patients are mainly due to macula edema, which is found in 29% diabetic patients with the over 20 years duration of disease. The aim of this study is to evaluate and investigate the possible correlation among changes of visual acuity (VA), central macular thickness (CMT) using Spectral Domain Optical Coherence Tomography (SD-OCT). Electrophysiological responses using multifocal electroretinography (MfERG) in diabetic macular edema (DME) following intravitreal injection of bevacizumab.
 Methods: Single arm clinical trial. Thirty-three eyes of 33 DME patients (16 non-proliferative diabetic retinopathy and 17 non-high-risk proliferative diabetic retinopathy), receives intravitreal bevacizumab 1,25mg. All patients underwent complete ophthalmic examination including ETDRS VA testing, Sixty-one scaled hexagon MfERG and SD-OCT scan at baseline, 1-week and 1-month post-injection. Components of the first order kernel (N1, N2 and P1) in central 2o were measured.
 Result : MfERG showed reduced P1 amplitude (P<0.05) at 1-week after injection followed by increased P1 amplitude (P>0.05) at 1-month after treatment as compared to the baseline in all subjects. There was 19% improvement CMT and 0.2Logmar VA improvement in 1-month post-injection compared to the baseline (P<005). This study showed no serious ocular adverse effects. There was no significant correlation between changes in visual acuity with changes in CMT or other MfERG parameters.
 Conclusion: Intravitreal injection bevacizumab resulting in improved VA, reduction in CMT and mild improvement in the MfERG responses. Although VA changes did not correlate with reduced CMT nor with improved responses of MfERG, the combined use of SD-OCT and MfERG may be used to evaluate macular function in DME patient with worsened visual acuity post anti-VEGF injection.

Spectral-Domain Optical Coherence Tomography Is More Sensitive for Hydroxychloroquine-Related Structural Abnormalities Than Short-Wavelength and Near-Infrared Autofluorescence.

PurposeTo analyze the appearance of structural abnormalities due to hydroxychloroquine (HCQ) toxicity by spectral-domain optical coherence tomography (SD-OCT) and short-wavelength autofluorescence (SW-AF) and near-infrared fundus autofluorescence (NIR-AF) imaging.MethodsThis retrospective cohort study included 88 eyes from 44 patients who had a history of or were currently taking HCQ. SD-OCT, SW-AF, and NIR-AF images were analyzed by two independent graders for the detection of HCQ-associated abnormalities.ResultsSixty eyes (30 patients, 68%) presented with no abnormalities for either imaging modality. Twenty eyes (10 patients, 23%) presented with parafoveal abnormalities (ellipsoid zone attenuation and/or interdigitation zone continuity loss) in SD-OCT scans but with qualitatively normal SW-AF and NIR-AF images. Eight eyes (four patients, 9%) presented with bull's-eye maculopathy in SW-AF and NIR-AF images, with corresponding outer retinal structures disrupted parafoveally in SD-OCT scans (“flying saucer” sign). No patients presented with normal SD-OCT scans and concurrent abnormalities in SW-AF or NIR-AF images.ConclusionsSD-OCT was more sensitive in detecting structural abnormalities than either SW-AF or NIR-AF imaging, suggesting its superiority as a screening imaging modality for HCQ toxicity. Maculopathy and abnormalities in the retinal pigment epithelium from HCQ toxicity can be appreciated in both SW-AF and NIR-AF images.Translational RelevanceAlthough debate exists regarding the best imaging modalities for screening patients for potential HCQ toxicity, our study supports the use of SD-OCT over both SW-AF and NIR-AF imaging as a screening modality.

OCT proves that vitreomacular adhesion is significantly more likely to develop vision-threatening retinal complications than vitreomacular separation

BackgroundSD-OCT is becoming commonplace in everyday practice. Vitreomacular adhesions (VMAs) are being more routinely diagnosed. Predictive studies to the natural course of VMA are thus clinically significant. Spectral domain-optical coherence tomography (SD-OCT) was presently utilized to analyze the incidence of floaters, the complete vitreomacular separation or VMA, the VMA complication, the vitreomacular angle (VMAng), and the complication mechanism.MethodsMonthly SD-OCT was performed on patients with/without symptomatic floaters. OCT allowed VMA and vitreomacular separation to be compared. The incidence was assessed applying one-tailed Fisher’s exact tests. The VMAngs between the inner retina and posterior hyaloid were measured, and the complication mechanism was studied using OCT image. For macular hole (MH), pre- and/or post-operative best corrected visual acuities (BCVAs; LogMAR), refractions and photoreceptor conditions were also evaluated.ResultsTotally, 124 eyes were included; there were 116 eyes with VMA and 8 eyes with vitreomacular separation. Considering the percentages over 124 eyes, floaters were present in 14.5% of enrolled eyes (=18/124), consisting of 12.9% of eyes with VMA (16/124) and 1.6% of eyes with vitreomacular separation (2/124). Moreover, there were twelve eyes (9.7%) with VMA-associated vision-threatening complications, including MH (n = 8; 6.5%), retinal detachment (RD; n = 2; 1.6%), vitreomacular traction (VMT; n = 1; 0.8%) and macular pucker (MP; n = 1; 0.8%). Eyes with initial VMA had a significantly greater possibility of complications than eyes with initial vitreomacular separation (p = 0.03). Among these eyes with MH (n = 8), the pre-operative BCVA (LogMAR) was 1.1 ± 0.5, which was insignificantly (p = 0.35) improved to 0.8 ± 0.7 post-operatively. The VMAng of VMA eyes with MHs was 24.2 ± 24.9° (n = 8). The critical VMAng was 13.3°.ConclusionsA minority of eyes with VMA or vitreomacular separation had floaters. Moreover, the use of SD-OCT could identify vision-threatening sequelae, namely MH, RD, MP and VMT, and this was significantly more frequent in eyes with VMA than in eyes with complete vitreomacular separation. Therefore, SD-OCT might be a useful way of identifying either identity, and evaluating VMA-associated complications. Whether VMA eyes with MH (n = 8) that have a VMAng greater than critical VMAng have a greater likelihood of tangential traction and subsequent MH needs further investigation.

Nystagmus and optical coherence tomography findings in CNGB3-associated achromatopsia

To describe the nystagmus characteristics of subjects with molecularly confirmed CNGB3-associated achromatopsia and report the spectral domain optical coherence tomography (SD-OCT) findings in these individuals. Adults and children with CNGB3-achromatopsia underwent visual acuity testing, ocular motility assessments, video nystagmography, and SD-OCT imaging. Qualitative assessment of foveal structure was performed by grading SD-OCT images into one of five categories. A total of 18 subjects (11 adults) were included. The majority demonstrated a phoria, with manifest strabismus present in only 3 subjects. The predominant nystagmus waveform within the cohort was pure pendular. Nine individuals demonstrated a mixture of waveforms. Nystagmus frequencies were 4-8 cycles/second, with no notable differences in eye movements between adults and children. SD-OCT imaging revealed a continuous ellipsoid zone (EZ) at the fovea in 2 subjects (grade 1) and EZ disruption (grade 2) in the remaining 16. Retinal structure characteristics were symmetrical in both eyes in each subject. In our study cohort, nystagmus in CNGB3-associated achromatopsia had distinctive features, and the majority of subjects had retinal abnormalities at the fovea on SD-OCT. Early use of SD-OCT in the clinical work-up may eliminate the need for more invasive investigations, such as neuro-imaging.

Noninvasive Diagnosis of Regional Alteration of Retinal Morphology and Structure with Optical Coherence Tomography in Rodents.

Spectral-domain optical coherence tomography (SD-OCT) produces high-resolution images of retinal cross sections and is becoming a method of choice for in vivo analyses of retinal morphology in rodents. We have adopted this technology to identify and analyze alterations of retinal structure, particularly those with regional and subtle changes. In this technical brief, we will demonstrate the use of SD-OCT in identifying subtle changes in retinal structure and morphology due to the effect of mosaic gene deletion in conditional knockout mice and of uneven distribution of intravitreally delivered compounds, review the application of SD-OCT in measuring pathological lesion volumes, and discuss the major benefits of SD-OCT technology over the traditional histological methods.

The Use of Spectral-Domain Optical Coherence Tomography to Detect Glaucoma Progression.

Detection of progression and measurement of rates of change is at the core of glaucoma management, and the use of Spectral Domain Optical Coherence Tomography (SD-OCT) has significantly improved our ability to evaluate change in the disease. In this review, we critically assess the existing literature on the use of SD-OCT for detecting glaucoma progression and estimating rates of change. We discuss aspects related to the reproducibility of measurements, their accuracy to detect longitudinal change over time, and the effect of aging on the ability to detect progression. In addition, we discuss recent studies evaluating the use of combined structure and function approaches to improve detection of glaucoma progression.

Monitoring Keratitis Resolution with Optical Coherence Tomography

Biomicroscopy is generally used, sometimes in conjunction with photography or ultrasound pachymetry, to monitor conditions involving stromal keratitis and edema. Spectral-domain optical coherence tomography (SD-OCT), a technology typically used to examine the posterior segment, may be useful in monitoring the therapeutic interventions for conditions involving corneal edema such as disciform keratitis. Two cases of disciform keratitis were followed to resolution using SD-OCT with anterior segment imaging software (Cirrus 4000; Carl Zeiss Meditec, Dublin, CA) to quantify decreasing edema throughout treatment. The thickest area of the cornea was located and measured across time using SD-OCT until resolution was achieved. Throughout each case, SD-OCT allowed precise localization of microcystic edema and keratic precipitates as well as the objective measurement of therapeutic interventions resulting in reduced edema and thickness. The use of SD-OCT allows objective measurements of corneal thickness and presents an additional method for following stromal keratitis with greater accuracy than can be appreciated using biomicroscopy alone.

Three-Dimensional Assessment of Vascular and Perivascular Characteristics in Subjects with Retinopathy of Prematurity

To study vascular features detected with spectral domain optical coherence tomography (SD-OCT) in subjects undergoing retinopathy of prematurity (ROP) screening. Cross-sectional study. Fifty-seven premature neonates, 10 with plus disease in at least 1 eye and 47without plus disease. Bedside noncontact SD-OCT imaging was performed after obtaining parental consent on 97 consecutive infants between January 2009 and September 2012. Fifty-seven subjects (31-49 weeks' post-menstrual age) who had an SD-OCT scan in at least 1 eye showing the edge of the optic nerve and at least 1 major retinal vascular arcade were included. One eye per subject was randomly selected for analysis. Two masked graders evaluated scans for (1) retinal vessel elevation, (2) scalloped retinal layers, (3) hyporeflective vessels, and (4) retinal spaces. To coalesce the weight of these features, a Vascular Abnormality Score by OCT (VASO) was created. For quantitative assessment of vessel elevation, retinal surface maps were created. Prevalence of SD-OCT vascular abnormalities, the VASO, intergrader agreement, and presence of elevation on surface maps. From among 67 SD-OCT characteristics that were recorded, the most common characteristics found were vessel elevation (44%), hyporeflective vessels (40%), scalloped layers (22%), and retinal spaces (11%). Features significantly associated with plus disease were vessel elevation (P= 0.01), hyporeflective vessels (P= 0.04), and scalloped retinal layers (P= 0.006). Intragrader agreement was between 74% and 90% for all features. The VASO was significantly higher in subjects with plus disease (P= 0.0013). On 3-dimensional SD-OCT volumes, eyes with plus disease had greater retinal surface elevation that more often matched en face retinal vascular patterns. We present a novel 3-dimensional analysis of vascular and perivascular abnormalities identified in SD-OCT images of eyes with ROP. The SD-OCT characteristics that are more common in eyes with plus disease provide the first invivo demonstration of the effects of vascular dilation and tortuosity on perivascular tissue. The VASO and surface maps also delineate the severity of vascular pathology in plus disease. Further studies evaluating these findings in eyes with pre-plus versus normal posterior pole vessels may determine the usefulness of SD-OCT in the early detection of vascular abnormalities in ROP.

Online monitoring of printed electronics by Spectral-Domain Optical Coherence Tomography

Spectral-Domain Optical Coherence Tomography (SD-OCT) is an optical method capable of 3D imaging of object's internal structure with micron-scale resolution. Modern SD-OCT tools offer the speed capable of online monitoring of printed devices. This paper demonstrates the use of SD-OCT in a simulated roll-to-roll (R2R) process through monitoring some structural properties of moving screen printed interdigitated electrodes. It is shown that structural properties can be resolved for speeds up to ca. 1 m/min, which is the first step towards application of this method in real manufacturing processes, including roll-to-roll (R2R) printing.

Sensitivity of fluorescein angiography alone or with SD-OCT for the diagnosis of myopic choroidal neovascularization

Myopic choroidal neovascularization (mCNV) has certain characteristics and features that distinguish it from choroidal neovascularization secondary to age-related macular degeneration. There may be angiographic diagnostic difficulties even when using the scanning laser ophthalmoscope, which gives more contrast and better definition than traditional angiography. The aim of the study is to compare the sensitivity of fluorescein angiography (FA) alone or combined with Spectral Domain Optical Coherence Tomography (SD-OCT) for assessing the incidence of mCNV. In this retrospective study, two authors reviewed the charts and images of patients with recent (<30 days) vision deterioration, pathologic myopia, axial length >26 mm, documentation or suspicion of mCNV or macular exudative pathologies at FA and OCT. They only examined the images at first presentation obtained by the multi-modal imaging system that combines Infrared reflectance, FA, and SD-OCT, (Spectralis, Heidelberg Engineering, Germany). The images selected were then evaluated by three other investigators in blinded, independent conditions, in order to make their diagnosis, which was noted or rated as doubtful if it could not be decided on the basis of FA alone. SD-OCT images were then shown and compared to IR and FA by each of the three investigators individually to formulate a conclusive diagnosis. A total of 71 eyes of 69 patients were suitable for the study, mean age 65.97±14.57 years, spherical equivalent refraction -8.82 ± 2.51 diopters. Concordance between the three examiners' interpretations of FA features and FA-guided SD-OCT was 50/71 (70.4 %) and 67/71 (94 %) respectively. Total agreement on diagnosis between the three examiners was achieved in 55 % of cases for FA (κ = 0.53, p < 0.001), and 94 % for FA-guided SD-OCT (k = -0.01, p = 0.5). The final diagnosis with FA and FA-guided SD-OCT differed in 29 cases (40 %; 95 % C.I. 29-42 %), whereas 12 (17 %) mCNV were overlooked at FA, and in 11 (15 %) cases none of the examiners reached a diagnosis based on FA alone. On the basis of FA alone, active mCNV can be misdiagnosed. The use of SD-OCT combined with FA should therefore be strongly considered.

Multicenter Spanish study of spectral‐domain optical coherence tomography in normal children

To compile a multicenter normative database of retinal nerve fibre layer (RNFL) and macular thicknesses and macular volume values in healthy Caucasian children 4-17 years using spectral-domain optical coherence tomography (SD-OCT). To analyse variations in the OCT measurements as a function of age, sex, refraction, and axial length (AL). An observational, multicenter and cross-sectional study among 301 healthy Caucasian children recruited at three Spanish centres was performed. To compile the database, each child underwent a dilated eye examination and a cycloplegic refraction, five AL measurements (IOL Master; Carl Zeiss Meditec, Dublin, CA, USA), five OCT scans with Cirrus OCT: three peripapillary RNFL scans (Optic Disc Cube 200X200 protocol) and two macular scans (Macular Cube 512X128 protocol). One eye of each subject was selected randomly for analysis. Two hundred eighty-three children (117 boys, 41.34%; 166 girls, 58.66%) were included in this study. The mean age of the children was 9.58 ± 3.12 years (range, 4-17). The mean SE was +0.63 ± 1.65 D; (range, -4.88 to +5.25). The mean AL was 22.94 ± 1.10 mm (range, 20.10-26.27). The mean global RNFL thickness was 97.40 ± 9.0 μm (range, 77-121.7 μm). Multivariate analysis showed a positive correlation between the RNFL and spherical equivalent (SE) (p = 0.014). The mean central macular thickness was 253.85 ± 19.76 μm, the average thickness 283.62 ± 14.08 μm, and the mean macular volume 10.22 ± 0.49 μm(3) . Multivariate analysis showed a positive correlation between central macular thickness and age (p < 0.001). Boys had a significantly thicker central macula than girls (p < 0.001). Normative paediatric SD-OCT data might facilitate use of SD-OCT for assessing childhood ophthalmic diseases. This study provides a multicenter paediatric normative database of SD-OCT peripapillary RNFL and macular data.

New Developments in the Pathophysiology and Management of Diabetic Retinopathy

New Developments in the Pathophysiology and Management of Diabetic Retinopathy

Imaging in vitreoretinal diagnostics

Imaging in vitreoretinal diagnostics

Characterizing the Phenotype and Genotype of a Family With Occult Macular Dystrophy

To characterize the phenotype of a white patient with occult macular dystrophy (OMD) and her clinically unaffected family members and to determine whether similar mutations were present in the RP1L1 gene in this family. Occult macular dystrophy is a rare macular dystrophy with central cone dysfunction hidden behind a normal fundus appearance that has been attributed to a mutation in the retinitis pigmentosa 1-like 1 (RP1L1) gene in 4 Japanese families. In this observational cross-sectional study of 1 white family with OMD, patients meeting the clinical criteria for OMD and their family members were evaluated by use of multifocal electroretinography, the Farnsworth D-15 color vision test, automated perimetry, spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence, and fundus photography. Fluorescein angiography was performed only on the proband. Members of this family were screened for genetic mutations in the RP1L1 gene. In the family studied, the clinically affected proband was noted to have loss of the foveal outer segments and absence of bowing of the inner segment/outer segment junction on SD-OCT scans. In addition, 1 clinically unaffected family member also demonstrated loss of the foveal photoreceptor outer segments and, therefore, decreased bowing of the inner segment/outer segment junction on SD-OCT scans. The fundus autofluorescence images of the eyes of the proband and her family members were normal. Although mutations in the RP1L1 gene have been identified in sporadic and autosomal dominant OMD pedigrees, no mutations in the RP1L1 gene were found in any of the participants. Loss of the outer segments of foveal photoreceptors can be detected and quantified by use of SD-OCT in patients with OMD. Similar findings are present in some clinically unaffected family members and may represent subclinical manifestations of the disease. Although mutations in the RP1L1 gene have been described in several Japanese families with OMD, there were no such mutations in this white family of European descent, which suggests that inherited OMD is a genetically heterogeneous disorder.

The use of SD-OCT in the differential diagnosis of dots, spots and other white retinal lesions.

To demonstrate the utility of a retinal imaging technique using spectral domain optical coherence tomography (SD-OCT) for creating a B-scan layer-by-layer analysis to aid in the differential diagnosis of various retinal dots, spots, and other white lesions. Review. A retrospective review of imaging studies performed with SD-OCT (Topcon, 3DOCT-2000, Oakland, NJ) at SUNY State College of Optometry. B-scan layer-by-layer analysis and unique SD-OCT reflectivity patterns of the following retinal white lesions are reviewed in the order of their retinal layer localization: myelinated nerve fiber layer, cotton wool spot, exudates, edema residues, drusen, fundus albipunctatus, Stargardt disease, Bietti crystalline dystrophy, punctate inner choroidopathy (PIC), presumed ocular histoplasmosis syndrome (POHS), post-photocoagulation chorioretinal scarring, and osseous choristoma. The reviewed images demonstrate the utility of SD-OCT in the identification of the unique characteristics of the presented retinal pathologies. SD-OCT is ideal for retinal layer localization of lesions, thus enhancing the differential diagnosis of retinal dots, spots, and other white lesions. Even though true pathognomonic patterns are rare, highly suggestive findings of certain retinal abnormalities often facilitate immediate recognition and diagnosis.

Race- and Sex-Related Differences in Retinal Thickness and Foveal Pit Morphology

To examine sex- and race-associated differences in macular thickness and foveal pit morphology by using spectral-domain optical coherence tomography (SD-OCT). One hundred eighty eyes of 90 healthy patients (43 women, 47 men) underwent retinal imaging with spectral-domain OCT. The lateral scale of each macular volume scan was corrected for individual differences in axial length by ocular biometry. From these corrected volumes, Early Treatment Diabetic Retinopathy Study (ETDRS) grids of retinal thickness were generated and compared between the groups. Foveal morphology was measured with previously described algorithms. Compared with the Caucasians, the Africans and African Americans had reduced central subfield thickness. Central subfield thickness was also reduced in the women compared with the men, although the women also showed significant thinning in parafoveal regions. There was no difference between the sexes in foveal pit morphology; however, the Africans/African Americans had significantly deeper and broader foveal pits than the Caucasians. Previous studies have reported race- and sex-associated differences in macular thickness, and the inference has been that these differences represent similar anatomic features. However, the data on pit morphology collected in the present study reveal an important and significant variation. Between the sexes, the differences are due to global variability in retinal thickness, whereas the variation in thickness observed between the races appears to be driven by differences in foveal pit morphology. These differences have important implications for the use of SD-OCT in detecting and diagnosing retinal disease.

Differentiation of Optic Nerve Head Drusen and Optic Disc Edema with Spectral-Domain Optical Coherence Tomography

To evaluate the efficacy of spectral-domain optical coherence tomography (SD-OCT) in differentiating optic disc edema (ODE) and optic nerve head drusen (ONHD) and to reveal the differential points. Comparative case series. Forty-five patients with ONHD, 15 patients with ODE, and 32 normal controls. Spectral-domain optical coherence tomography was performed with scans on the optic nerve head and measurements of retinal nerve fiber layer thickness. Qualitative findings of optic nerve head scans and retinal nerve fiber layer thickness profiles on SD-OCT. Optic nerve head drusen was visualized as a focal, hyperreflective, subretinal mass with a discrete margin on SD-OCT. The retinal nerve fiber layer was deformed and showed pseudoedema and high reflectance. The outer nuclear layer smoothly covered the drusen, which led to a hyporeflective, boot-shaped area adjacent to the drusen. In ODE, peripapillary retinal nerve fiber layers were significantly thicker in all sections than ONHD (average thickness of ODE: 174.1±53.5 μm vs ONHD: 119.2±20.2 μm vs control: 103.4±19.1 μm, P<0.001). Retinal nerve fiber thickness in the nasal section provides a good differential marker for ODE from ONHD (area under receiver operating characteristic curve = 0.866). With the use of SD-OCT, noninvasive and accurate differentiation of ONHD and ODE is possible.

Ocular Coherence Tomography and Diabetic Eye Disease

Optical Coherence Tomography (OCT) is a high-resolution, cross-sectional imaging technique that allows detailed assessment of retinal thickness and morphologic evaluation of the neurosensory retinal layers. OCT imaging has rapidly been integrated into diagnosis and management of diabetic macular edema (DME) in routine clinical practice and clinical trials. OCT findings correlate well with other evaluation techniques for DME. Although there is a moderate correlation between OCT measured retinal thickness and visual acuity, OCT cannot replace visual acuity because there is a high degree of variability. Recent improvements in OCT technology have led to widespread interest in the use of spectral domain OCT, which is faster and has higher resolution than time domain OCT. Future research in OCT imaging will likely result in improvements in image quality. The ability to combine OCT with other various diagnostic modalities will further improve the evaluation of DME in both clinical practice and trials.