Spectral-domain optical coherence tomography use in macular diseases: a review

Difference of central foveal thickness measurement in patients with macular edema using optical coherence tomography in different display modes

Purpose

To assess the differences in the measurement of central foveal thickness (CFT) in patients with macular edema (ME) between two display modes (1:1 pixel and 1:1 micron) on optical coherence tomography (OCT).

Design

This is a retrospective, cross-sectional study.

Methods

Group A consisted of participants with well-horizontal OCT B-scan images and group B consisted of participants with tilted OCT B-scan. We manually measured the CFT under the two display modes, and the values were compared statistically using the paired t-test. Spearman's test was used to assess the correlations between the OCT image tilting angle (OCT ITA) and the differences in CFT measurement. The area under the curve (AUC) was calculated to define the OCT ITA cutoff for a defined CFT difference.

Results

In group A, the mean CFT in the 1:1 pixel display mode was 420.21 ± 130.61 µm, similar to the mean CFT of 415.27 ± 129.85 µm in the 1:1 micron display mode. In group B, the median CFT in the 1:1 pixel display mode is 409.00 μm (IQR: 171.75 μm) and 368.00 μm (IQR: 149.00 μm) in the 1:1 micron display mode. There were significant differences between the two display modes with the median (IQR) absolute difference and median (IQR) relative difference of 38.00 μm (75.00 μm) and 10.19% (21.91%) (all p = 0.01). The differences in CFT measurement between the two display modes were correlated with the OCT ITA (absolute differences, r = 0.88, p < 0.01; relative differences, r = 0.87, p < 0.01). The AUC for a predefined CFT difference was 0.878 (10 μm), 0.933 (20 μm), 0.938 (30 μm), 0.961 (40 μm), 0.962 (50 μm), and 0.970 (60 μm).

Conclusion

In patients with DM, when the OCT B-scan images were well-horizontal, manual CFT measurements under the two display modes were similar, but when the B-scan images were tilted, the CFT measurements were different under the two display modes, and the differences were correlated to the OCT ITA.

Automatic Segmentation of Retinal Layers in Multiple Neurodegenerative Disorder Scenarios

Retinal Optical Coherence Tomography (OCT) allows the non-invasive direct observation of the central nervous system, enabling the measurement and extraction of biomarkers from neural tissue that can be helpful in the assessment of ocular, systemic and Neurological Disorders (ND). Deep learning models can be trained to segment the retinal layers for biomarker extraction. However, the onset of ND can have an impact on the neural tissue, which can lead to the degraded performance of models not exposed to images displaying signs of disease during training. We present a fully automatic approach for the retinal layer segmentation in multiple neurodegenerative disorder scenarios, using an annotated dataset of patients of the most prevalent NDs: Alzheimer's disease, Parkinson's disease, multiple sclerosis and essential tremor, along with healthy control patients. Furthermore, we present a two-part, comprehensive study on the effects of ND on the performance of these models. The results show that images of healthy patients may not be sufficient for the robust training of automated segmentation models intended for the analysis of ND patients, and that using images representative of different NDs can increase the model performance. These results indicate that the presence or absence of patients of ND in datasets should be taken into account when training deep learning models for retinal layer segmentation, and that the proposed approach can provide a valuable tool for the robust and reliable diagnosis in multiple scenarios of ND.

Preoperative fundoscopy versus optical coherence tomography to detect occult maculopathy during cataract surgery preassessment

PURPOSE

To assess the proportion of maculopathy detectable only on optical coherence tomography (OCT) versus slit lamp indirect ophthalmoscopy (SLIO) during cataract assessment.

METHODS

Population: Consecutive patients attending cataract assessments.

DATA COLLECTION

All patients underwent OCT and SLIO. SLIO findings were recorded before reviewing OCT. Scans were examined to compare with recorded SLIO findings.

PRIMARY OUTCOME

analyse the proportion of eyes with maculopathy missed by SLIO.

SECONDARY OUTCOME

to assess the proportion of patients with maculopathy on OCT, the incidence of maculopathy in the fellow eye on OCT and proportion with cataracts too dense to allow SLIO or OCT.

RESULTS

Six hundred twenty-six patients were enroled. Eighty (12.8%) had maculopathy detectable only on OCT which included: 26 (4.2%) epiretinal membrane (ERM), 25 (4%) dry age-related macular degeneration (AMD), 19 (3%) vitreomacular traction (VMT), 5 (0.8%) lamellar macular hole (LMH), 2 (0.3%) cystoid macular oedema (CMO) and 1 (0.2%) wet AMD. 166 (26.5%) had maculopathy on OCT, of which only 48 (7.7%) had known history of maculopathy. In fellow eyes, 29 (4.6%) had significant findings and 29 (4.6%) were unable to have SLIO or OCT due to dense cataract.

CONCLUSIONS

A quarter of the patients had occult maculopathy. One-tenth of the occult maculopathy were missed without OCT, with ERM, dry AMD, VMT, LMH, CMO and wet AMD being the primary missed diagnosis. Less than 5% had occult maculopathy in fellow eye, and <5% had dense cataracts where neither SLIO nor OCT was not possible.

A deep network embedded with rough fuzzy discretization for OCT fundus image segmentation

The noise and redundant information are the main reasons for the performance bottleneck of medical image segmentation algorithms based on the deep learning. To this end, we propose a deep network embedded with rough fuzzy discretization (RFDDN) for OCT fundus image segmentation. Firstly, we establish the information decision table of OCT fundus image segmentation, and regard each category of segmentation region as a fuzzy set. Then, we use the fuzzy c-means clustering to get the membership degrees of pixels to each segmentation region. According to membership functions and the equivalence relation generated by the brightness attribute, we design the individual fitness function based on the rough fuzzy set, and use a genetic algorithm to search for the best breakpoints to discretize the features of OCT fundus images. Finally, we take the feature discretization based on the rough fuzzy set as the pre-module of the deep neural network, and introduce the deep supervised attention mechanism to obtain the important multi-scale information. We compare RFDDN with U-Net, ReLayNet, CE-Net, MultiResUNet, and ISCLNet on the two groups of 3D retinal OCT data. RFDDN is superior to the other five methods on all evaluation indicators. The results obtained by ISCLNet are the second only inferior to those obtained by RFDDN. DSC, sensitivity, and specificity of RFDDN are evenly 3.3%, 2.6%, and 7.1% higher than those of ISCLNet, respectively. HD95 and ASD of RFDDN are evenly 6.6% and 19.7% lower than those of ISCLNet, respectively. The experimental results show that our method can effectively eliminate the noise and redundant information in Oct fundus images, and greatly improve the accuracy of OCT fundus image segmentation while taking into account the interpretability and computational efficiency.

The Classification of Common Macular Diseases Using Deep Learning on Optical Coherence Tomography Images with and without Prior Automated Segmentation

We compared the performance of deep learning (DL) in the classification of optical coherence tomography (OCT) images of macular diseases between automated classification alone and in combination with automated segmentation. OCT images were collected from patients with neovascular age-related macular degeneration, polypoidal choroidal vasculopathy, diabetic macular edema, retinal vein occlusion, cystoid macular edema in Irvine-Gass syndrome, and other macular diseases, along with the normal fellow eyes. A total of 14,327 OCT images were used to train DL models. Three experiments were conducted: classification alone (CA), use of automated segmentation of the OCT images by RelayNet, and the graph-cut technique before the classification (combination method 1 (CM1) and 2 (CM2), respectively). For validation of classification of the macular diseases, the sensitivity, specificity, and accuracy of CA were found at 62.55%, 95.16%, and 93.14%, respectively, whereas the sensitivity, specificity, and accuracy of CM1 were found at 72.90%, 96.20%, and 93.92%, respectively, and of CM2 at 71.36%, 96.42%, and 94.80%, respectively. The accuracy of CM2 was statistically higher than that of CA (p = 0.05878). All three methods achieved AUC at 97%. Applying DL for segmentation of OCT images prior to classification of the images by another DL model may improve the performance of the classification.

Clinical characteristics of patients with epiretinal membrane-Foveoschisis

PURPOSE

The purpose of this study is to investigate the clinical and morphological characteristics of epiretinal membrane (ERM)-Foveoschisis.

METHODS

Medical charts of 2088 patients diagnosed with idiopathic ERM were screened and eyes with ERM-Foveoschisis were included. All eyes underwent a complete ophthalmological examination including spectral domain optical coherence tomography (SD-OCT). OCT features and best corrected visual acuity (BCVA) were analysed. ERM-Foveoschisis was defined as open, closed, elevated or flat based on the OCT features. Ellipsoidal zone (EZ) abnormality, intraretinal cystoid spaces, central foveal thickness (CFT), posterior vitreous detachment (PVD) and lens status were assessed.

RESULTS

One hundred-sixty-six patients (175 eyes) (72% female, mean age 70.46 years) were included. Incidence of ERM-Foveoschisis was 6.7%. Open type was seen in 86.8% and had a significantly better mean BCVA than closed type (p = 0.01). No statistically significant difference of mean BCVA was noted between the elevated and flat types. Mean BCVA was significantly lower in eyes with EZ abnormality (p = 0.03) and eyes with intraretinal cystoid spaces (p = 0.02). Patients with 'closed' ERM-Foveoschisis showed a significant higher median CFT than 'open' ERM-Foveoschisis (respectively, 364 µm and 176 µm, p < 0.001). A total of 81.9% eyes had PVD.

CONCLUSION

We differentiated four morphological types of ERM-Foveoschisis based on the OCT examination. Closed ERM-Foveoschisis presented with a higher CFT and lower BCVA than the open type. ERM-Foveoschisis with cystoid intraretinal spaces presented with a lower BCVA. The impact of the morphological types of the ERM-Foveoschisis on the clinical course and for therapy decision requires further long-term studies.

Plasma homocysteine and macular thickness in older adults-the Rugao Longevity and Aging Study

OBJECTIVES

To determine the association of plasma homocysteine levels with retinal layer thickness in a large community cohort of older adults.

METHODS

The Rugao Longevity and Ageing Study is an observational, prospective and community-based cohort study. A total of 989 older adults who underwent spectral-domain optical coherence tomography (SD-OCT) were included and analyzed. Foveal, macular retinal nerve fibre layer (mRNFL) and ganglion cell layer plus inner plexiform layer (GC-IPL) thicknesses were measured by SD-OCT. Plasma homocysteine levels were measured using chemiluminescence immunoassay. Linear regression analyses were performed to evaluate the relationship between plasma homocysteine and retinal layer thickness while controlling for confounding factors.

RESULTS

Of the 989 participants, 500 (50.56%) were men. The mean age was 78.26 (4.58) years, and the mean plasma homocysteine level was 16.38 (8.05) μmol/L. In multivariable analyses, each unit increase in plasma homocysteine was associated with an 8.84 × 10^-2 (95% CI: -16.54 × 10^-2 to -1.15 × 10^-2, p = 0.032) μm decrease in the average inner thickness of the GC-IPL after controlling for confounding factors. The association remained significant even in participants without major cardiovascular disease or diabetes (β = -10.33 × 10^-2, 95% CI: -18.49 × 10^-2 to -2.18 × 10^-2, p = 0.013). No significant associations of plasma homocysteine levels with macular thickness or mRNFL were found in primary and sensitivity analyses (p > 0.05).

CONCLUSIONS

Increased plasma homocysteine levels are associated with a thinner GC-IPL. Plasma homocysteine may be a risk factor for thinner retinas in older adults.

Intra- and Inter-Slice Contrastive Learning for Point Supervised OCT Fluid Segmentation

OCT fluid segmentation is a crucial task for diagnosis and therapy in ophthalmology. The current convolutional neural networks (CNNs) supervised by pixel-wise annotated masks achieve great success in OCT fluid segmentation. However, requiring pixel-wise masks from OCT images is time-consuming, expensive and expertise needed. This paper proposes an Intra- and inter-Slice Contrastive Learning Network (ISCLNet) for OCT fluid segmentation with only point supervision. Our ISCLNet learns visual representation by designing contrastive tasks that exploit the inherent similarity or dissimilarity from unlabeled OCT data. Specifically, we propose an intra-slice contrastive learning strategy to leverage the fluid-background similarity and the retinal layer-background dissimilarity. Moreover, we construct an inter-slice contrastive learning architecture to learn the similarity of adjacent OCT slices from one OCT volume. Finally, an end-to-end model combining intra- and inter-slice contrastive learning processes learns to segment fluid under the point supervision. The experimental results on two public OCT fluid segmentation datasets (i.e., AI Challenger and RETOUCH) demonstrate that the ISCLNet bridges the gap between fully-supervised and weakly-supervised OCT fluid segmentation and outperforms other well-known point-supervised segmentation methods.

PRE-RETINOPATHY OF TYPE 1 DIABETES IN THE CONTEXT OF FUNCTIONAL, STRUCTURAL AND MICROCIRCULATORY CHANGES IN THE MACULAR AREA

AIM

The authors assessed the development of intraocular changes in type 1 diabetes (T1DM) from the onset of the disease leading to diabetic retinopathy (DR). The quote: &#8220;There must be an intermediate stage between the physiological intraocular finding and the diabetic retinopathy itself &#8220;, (prof. Jan Vav&#345;inec).

METHODS

A two-year study (2018 and 2019) was conducted at the Department of Ophthalmology of the Teaching Hospital Kralovske Vinohrady in Prague (Czech Republic). There were 54 patients aged 17-42 years, the detection of T1DM ranged between the 1st and 14th year of life, with a duration of 12-35 years. Individual patients were always examined simultaneously by three methods: CS (contrast sensitivity), SD-OCT (spectral domain optical coherence tomography) and OCT-A (optical coherence tomography-angiography). We examined 106 eyes once and in a comprehensive manner.

RESULTS

We have shown that there is an intermediate stage between the physiological finding on the retina and DR, so-called diabetic pre-retinopathy (DpR). Subsequent redistribution of the observed into two DpR subgroups was derived from the size of the FAZ, either with its smaller area or with a larger area determining the microvascularity of the central area of the retina. The results of both other methods were assigned to these values. For SD-OCT, the depth of the fovea (the difference between the central retinal thickness and the total average retinal thickness) was determined, which was affected by the increased the macular cubature. In all patients it was on average 10.3 &#956;m3. The retina in the central area was significantly strengthened compared to the healthy population at the level of significance p 0,001. We divided the actual DpR into an image: DpR1 in 26.5 % of eyes - condition with an average shallower fovea only by 21.5 &#956;m below the level of the surrounding retina and an average narrower FAZ: 0.165 mm2 and with a more significant decrease in CS; DpR2 in 40.5 % of eyes - condition with average deeper fovea by 42 &#956;m, i.e., more significantly and average larger FAZ: 0.325 mm2 with lower decrease of CS. At the same time, other changes in microvascularity were noted, such as disorders in the sense of non-perfusion in the central part of the retina of various degrees. This finding differed significantly from changes in already established (non-proliferative) NPDR in 36 % of eyes, when a significant decrease in CS with normal visual acuity was found 4/4 ETDRS. Statistical differences in CS between DpR1 and DpR2 and NPDR were determined - always p 0.001. The average depth of the fovea was NPDR: 29.5 &#956;m. NPDR had the largest average FAZ: 0.56 mm2. Also significant were the most significant changes in non-perfusion and especially the presence of microaneurysms.

CONCLUSIONS

These three non - invasive methods helped to monitor the dynamics of the development of ocular changes in T1DM of better quality than the determination of visual acuity and ophthalmoscopic examination. Increased retinal volume induced hypoxia of visual cells with subsequent dual autoregulatory mechanism conditioning two types of diabetic pre-retinopathy before the onset of DR.

Agreement and differences between macular values in children using two types of spectral optical coherence tomography

OBJECTIVES

To determine the degree of agreement and differences between macular parameters according to sex, age, laterality, ethnicity and type of optical coherence tomography (OCT) in paediatric patients.

MATERIALS AND METHODS

Prospective, transversal, and comparative study. OCT Spectralis and OCT Cirrus were used to obtain the macular values of both eyes in 100 patients between 5 and 15 years without ocular pathology. Due to the similarity between the values of both eyes, in the final sample we only considered the right eyes (OD) (n = 100).

RESULTS

The average central macular thickness (CMT) was 244.2 μm with Cirrus and 261.7 μm with Spectralis. The degree of agreement for the GMC was moderate (Intraclass Correlation Coefficient: 0.66) and from low to very low in the other quadrants. The GMC values of both systems were significantly higher in men than in women (P < .05). The macular retinal nerve fibre layer (mRNC), ganglion cell layer (GCC), the inner plexiform layer (IPLC), and the inner nuclear layer (INFL) had significantly higher values in men than in women (P < .01). There were no statistically significant differences in the GMC by age and laterality, however it was significantly higher in ethnic European children than in ethnic Latin American children; Cirrus (P = .042) and Spectralis (P = .033).

CONCLUSIONS

Macular parameters obtained by OCT Spectralis and OCT Cirrus should not be interchangeable in pediatric patients.

Microperimetry-Assessed Functional Alterations and OCT-Changes in Patients after Retinal Detachment Surgery Using Pars Plana Vitrectomy and SF6 Tamponade

Background: We study the retinal function measured by macular integrity assessment microperimetry (MAIA) and structural changes assessed by scanning swept source optical coherence tomography (SS-OCT) between healthy individuals and patients undergoing pars plana vitrectomy (PPV) after rhegmatogenous retinal detachment (RRD). Methods: Cross-sectional study. Early Treatment Diabetic Retinopathy Study (ETDRS) grids were measured by SS-OCT and compared with the MAIA parameters. Results: Thirty-eight eyes with RRD (19 macula-on and 19 macula-off) were compared with 113 healthy eyes. The retinal sensitivity and average total threshold were reduced in all sectors in the RRD group; macular integrity index was increased. Macular thicknesses in total retina and ganglion cell layer (GCL)++ protocols were higher in the RRD group in nasal outer (NO) and central (C) sectors and only in C sector for GCL+ protocol. Thicknesses were lower in total retina, GCL++ protocols in the temporal outer (TO) sector and in the GCL+ protocol in NO sector. Best-corrected visual acuity (BCVA) correlated moderately with retinal sensitivity in all sectors and in just several sectors with time between the date of surgery and the test. The central nasal (CN) sector thickness and the average total threshold were higher in the macula-on subgroup. Conclusions: RRD and subsequent surgery results in functional and structural changes, especially in individuals with macular detachment.

Agreement and differences between macular values in children using two types of spectral optical coherence tomography

OBJECTIVE

To determine the degree of agreement and differences between macular parameters according to sex, age, laterality, ethnicity and type of optical coherence tomography (OCT) in paediatric patients.

MATERIALS AND METHODS

Prospective, transversal, and comparative study. OCT Spectralis and OCT Cirrus were used to obtain the macular values of both eyes in 100 patients between 5 and 15years without ocular pathology. Due to the similarity between the values of both eyes, in the final sample we only considered the right eyes (OD) (n=100).

RESULTS

The average central macular thickness (CMT) was 244.2μm with Cirrus and 261.7μm with Spectralis. The degree of agreement for the GMC was moderate (intraclass correlation coefficient: 0.66) and from low to very low in the other quadrants. The GMC values of both systems were significantly higher in men than in women (P<.05). The macular retinal nerve fibre layer (mRNC), ganglion cell layer (GCC), the inner plexiform layer (IPLC), and the inner nuclear layer (INFL) had significantly higher values in men than in women (P<.01). There were no statistically significant differences in the GMC by age and laterality, however it was significantly higher in ethnic European children than in ethnic Latin American children; Cirrus (P=.042) and Spectralis (P=.033).

CONCLUSIONS

Macular parameters obtained by OCT Spectralis and OCT Cirrus should not be interchangeable in pediatric patients.

Macular microhole and foveal red spot syndrome: a critical review of the literature

PURPOSE

The purpose of this article is to review the literature on nomenclature, natural history, clinical features, diagnosis, management, and prognosis of both macular microhole (MMH) and foveal red spot syndrome (FRS).

METHODS

A PubMed primary literature search (February 1, 2020) utilizing the terms macular microhole, foveal red spot syndrome, and outer retinal hole was conducted. All chosen articles were case reports or case series. Articles qualified for inclusion if they documented symptoms, imaging findings, or followed patients longitudinally.

RESULTS

A total of 14 studies from 1988 to 2019 that evaluated either MMH, FRS, or both were included in the review. No comparative study between the two defects was found. Studies often used the terms FRS and MMH interchangeably to reference both partial- and full-thickness lesions of the macula. Spectral-domain optical coherence tomography (SD-OCT) was most frequently able to identify these lesions and revealed an absence of all neural retinal layers from the inner limiting membrane (ILM) to the retinal pigment epithelium (RPE) in the full-thickness lesions while the partial-thickness lesions most often involved the photoreceptor layer (PRL) and less frequently the external limiting membrane (ELM). OCT revealed that vitreomacular traction (VMT) was involved in the natural history of both FRS and MMH for a significant subset of patients.

CONCLUSION

The terms MMH and FRS have been used interchangeably in the literature. Advances in OCT have revealed that MMHs and FRSs are distinct but sometimes overlapping entities. We suggest that MMH and FRS are similar entities defined as one or more sharply defined lesions in the fovea of the eye < 150 μm in size. MMHs are a full-thickness defect of the entire neuroretina at the center of the foveola while FRSs are partial-thickness lesions. Current literature suggests that there may be subtle differences in the pathogenesis, clinical features, and diagnosis between MMH and FRS; however, prognosis and management for both are favorable. Lastly, we suggest that the terms outer lamellar macular microholes and full-thickness macular microholes may be the more appropriate terminologies to refer to FRS and MMH, respectively.

Predicting response of ischemic central retinal vein occlusion to bevacizumab injections: 1 year follow-up

PURPOSE

To identify baseline optical coherence tomography (OCT) factors in ischemic central retinal vein occlusion (CRVO) that predict response to bevacizumab injections.

METHODS

Patients underwent OCT at diagnosis and the central macular thickness, subretinal fluid width and height as well as the presence of intraretinal cysts were measured. The extent of disorganized retinal inner layers, outer plexiform layer (OPL), external limiting membrane, ellipsoid zone and cone outer segment tips (COST) was recorded. Patients received three consecutive monthly injections of bevacizumab followed by pro re nata treatment.

RESULTS

Overall 32 eyes of 32 patients aging 69.4 ± 12.7 years were included. In univariate correlational analyses baseline OPL disruption (- 41, p = 0.02), EZ disruption (r = - 0.36, p = 0.05) and COST disruption (r = - 0.37, p = 0.04) correlated with deterioration in BCVA at 1 year. Partial least squares demonstrated that the factors most largely associated with deterioration in BCVA were COST disruption and OPL disruption followed by EZ disruption, while worst vision at baseline was associated with improvement in vision.

CONCLUSION

In patients with ischemic CRVO treated with bevacizumab, BCVA improvement at 1 year can be partially predicted from baseline OCT measurements by the extent of COST, OPL and EZ disruption.

Measurement of macular thickness with optical coherence tomography: impact of using a paediatric reference database and analysis of interocular symmetry

PURPOSE

Optical coherence tomography (OCT) software is used to classify abnormality of macular thickness by colour category based on reference data from adult series. We assessed the impact of using paediatric reference thickness values for macular thickness instead of adult reference values.

METHODS

Cross-sectional study. Primary and tertiary healthcare setting. Out of 140 healthy participants aged 5 to 18 years, 126 were eligible, 83% from European origin. Following a dilated eye examination and cycloplegic refraction, participants underwent macular scanning with OCT (Topcon 3D OCT-2000). Macular thickness paediatric reference values were recorded by spherical equivalent (SE) and sex, and the specific agreement between paediatric and adult reference values below or equal to percentile 5 and above percentile 95 was estimated. The absolute interocular differences for all macular parameters were determined.

RESULTS

Multivariate regression analysis confirmed statistically independent positive associations between SE and average thickness, total volume, and temporal and inferior outer quadrants (all p values ≤ 0.003). The analysis also revealed higher values in males for average thickness, central thickness, and all inner macula quadrants (all p values ≤ 0.039). The use of the adult database only detected 49% of the extreme values (≤ p5 and > p95) in our paediatric sample. The 95th percentile limits for absolute interocular differences for all macular parameters ranged from 12 to 17 μm.

CONCLUSIONS

OCT-based macular reference values for paediatric SE and sex improve detection of children with abnormal macular thicknesses. Interocular differences exceeding standard references for macular parameters should be considered for further examinations.

Correlation between Macular Pigment Optical Density and Neural Thickness and Volume of the Retina

Macular pigment (MP), which is composed of lutein/zeaxanthin/mezo-zeaxanthin, is concentrated in the central part of the retina, the macula. It protects the macula by absorbing short-wavelength light and suppressing oxidative stress. To evaluate whether MP levels are related to retinal neural protection and resulting health, we analyzed the association between the MP optical density (MPOD), and the macular thickness and volumes. Forty-three eyes of 43 healthy adult volunteers (21 men and 22 women; age: 22–48 (average 31.4 ± 1.1) years) were analyzed. Highly myopic eyes (<-6 diopters) were excluded. MPOD was measured using MPS2®, and the neural retinal thickness and volume were measured using optical coherence tomography. The mean MPOD was 0.589 ± 0.024, and it positively correlated with the central retinal thickness (P = 0.017, R = 0.360) and retinal volume of the fovea (1-mm diameter around the fovea; P = 0.029, R = 0.332), parafovea (1–3-mm diameter; P = 0.002, R = 0.458), and macula (6-mm diameter; P = 0.003, R = 0.447). In the macular area (diameter: 6 mm), MPOD was correlated with the retinal neural volume of the ganglion cell layer (P = 0.037, R = 0.320), inner plexiform layer (P = 0.029, R = 0.333), and outer nuclear layer (P = 0.020, R = 0.353). Thus, MPOD may help in estimating neural health. Further studies should determine the impact of MP levels on neuroprotection.

Dynamic intraoperative optical coherence tomography for inverted internal limiting membrane flap technique in large macular hole surgery

BACKGROUND/OBJECTIVES

To assess the efficacy of dynamic intraoperative spectral-domain optical coherence tomography (iSD-OCT) imaging for inverted internal limiting membrane (ILM) flap technique (IILMFT) in large macular hole (MH) surgery.

SUBJECTS/METHODS

Prospective, non-randomized, observational study was conducted on 8 eyes of 7 patients with large, chronic and recurrent MHs, which were treated by pars plana vitrectomy (PPV) with IILMFT. All patients underwent standard pre- and postoperative examination. The iSD-OCT imaging was performed using microscope integrated systems before, during, and after ILM peeling. The iSD-OCT data were post-processed using graphic software and reviewed for tissue behavior and instruments position.

RESULTS

The real-time iSD-OCT-assisted IILMFT allowed for real-time imaging of the entire surgery with visualization of the MH, vitreoretinal instruments, and all steps of inverted ILM flap formation. In spite of shadowing created by the steel instruments, it was possible to follow and control the distance between the instrument tips and retinal layers. Dynamic imaging of the surgical maneuvers including ILM peeling and mechanical apposition of MH edges revealed the iatrogenic impact on the retina (depression and appearance of hyporeflective zones). iSD-OCT imaging could confirm the proper position of the inverted ILM flap at the very end of the surgery after fluid-air exchange.

CONCLUSIONS

iSD-OCT imaging is an effective tool for learning and performing a well-controlled and safe inverted ILM flap technique in patients with large MH. Clinical significance of the structural iSD-OCT findings has to be further studied.

Lamellar Macular Holes: The Role of Microperimetry in Functional Assessment

Introduction

The aim of our observational cross-sectional study was to evaluate the association between visual function and anatomical characteristics of LMH, considering in particular different subtypes of LMH and their features.

Materials and Methods

This observational clinical study has been conducted in the Ophthalmology Clinic, ASST-Sette Laghi, University of Insubria of Varese-Como, Italy. Included patients underwent a complete ophthalmological examination, as well as MP1 microperimetry evaluation and optical coherence tomography (OCT). Two experienced masked observers evaluated OCT imaging in order to assess the integrity of the photoreceptor layer (interdigitation zone and ellipsoid zone: IZ/EZ) and the external limiting membrane (ELM).

Results

Twenty-five patients affected by an LMH were evaluated. Eighteen eyes of 18 patients met the study criteria and were included. Based on morphological and functional data, LMHs were divided into two subgroups: tractional (tLMH) and degenerative (dLMH). We identified 11 tLMHs and seven dLMHs. Functional parameters showed a significative difference in visual acuity and retinal sensitivity between the two groups, respectively: (sample median and the interquartile range) 0.0 (0.0; 0.09) LogMAR vs 0.15 (0.09; 0.52) LogMAR and 16.2 (14.2; 17.7) dB vs 10.0 (7.5; 11.8) dB (p < 0.05). Fixation was predominantly central in 90.9% of tLMH vs 71.4% of dLMH and stable in 81.8% tLMH vs 42.9% dLMH, but the differences were not statistically significant. Tractional and degenerative LMHs showed no significant differences in central foveal thickness. Conversely, LMH depth and horizontal diameters appeared different between the two groups. Tractional LMH showed a greater depth 257 (205; 278) μm vs 190 (169; 249) μm, whereas degenerative LMH showed a greater horizontal diameter 653 (455; 750) μm vs 429 (314; 620) μm (p < 0.05). IZ/EZ line was unaffected in 81.8% of tLMHs eyes versus 14.3% of dLMHs eyes (p < 0.05). Visual acuity and retinal sensitivity were higher in eyes with integrity of both IZ/EZ and ELM compared to those with a disruption of one or both layers (p < 0.05).

Conclusion

Two different subtypes of LMH showed peculiar functional aspects due to their morphological features. Tractional LMHs revealed higher visual acuity and retinal sensibility due to the relative preservation of the outer retinal layers compared to degenerative LMHs. Moreover, we underlined the importance of microperimetry to better identify functional defects in macular degenerative pathologies.

Automated segmentation of macular edema in OCT using deep neural networks

Macular edema is an eye disease that can affect visual acuity. Typical disease symptoms include subretinal fluid (SRF) and pigment epithelium detachment (PED). Optical coherence tomography (OCT) has been widely used for diagnosing macular edema because of its non-invasive and high resolution properties. Segmentation for macular edema lesions from OCT images plays an important role in clinical diagnosis. Many computer-aided systems have been proposed for the segmentation. Most traditional segmentation methods used in these systems are based on low-level hand-crafted features, which require significant domain knowledge and are sensitive to the variations of lesions. To overcome these shortcomings, this paper proposes to use deep neural networks (DNNs) together with atrous spatial pyramid pooling (ASPP) to automatically segment the SRF and PED lesions. Lesions-related features are first extracted by DNNs, then processed by ASPP which is composed of multiple atrous convolutions with different fields of view to accommodate the various scales of the lesions. Based on ASPP, a novel module called stochastic ASPP (sASPP) is proposed to combat the co-adaptation of multiple atrous convolutions. A large OCT dataset provided by a competition platform called "AI Challenger" are used to train and evaluate the proposed model. Experimental results demonstrate that the DNNs together with ASPP achieve higher segmentation accuracy compared with the state-of-the-art method. The stochastic operation added in sASPP is empirically verified as an effective regularization method that can alleviate the overfitting problem and significantly reduce the validation error.

What Does Optical Coherence Tomography Offer for Evaluating Physical Disability in Patients with Multiple Sclerosis?

Visual dysfunction is one of the most common clinical manifestations of multiple sclerosis (MS). For example, optic neuritis is the onset symptom in 20% of patients with MS. Visual pathway impairment presents in most patients with MS, including patients who have not experienced optic neuritis. During the last decade, many clinical trials of MS have included visual outcomes. One tool used in these studies, optical coherence tomography, is a non-contact, noninvasive, high-resolution optical imaging technology that helps segmentation and measurement of specific retinal layers using computerized algorithms. Optical coherence tomography is used in various stages of MS from diagnosis to treatment of the disease. In this review, we summarize the use of optical coherence tomography in MS and study its usefulness for evaluating the physical disabilities of MS patients.

Budget impact analysis of ocriplasmin for the treatment of symptomatic vitreomacular adhesion in the USA

Background: Vitreomacular traction (VMT) treatment options include watchful waiting, vitrectomy and intravitreal ocriplasmin injection (Jetrea®). This analysis used results from the recently completed OASIS randomized clinical trial to evaluate the 2-year budget impact of ocriplasmin injection availability for treatment of Stage I or II VMT without epiretinal membrane formation in a modeled US health plan. Materials & methods: VMT prevalence, treatment patterns and disease resolution rates were from literature, a US retinal-specialist survey and the OASIS trial. Medicare payment rates were applied and a national scenario analysis was conducted. Results: With ocriplasmin available, vitrectomy use and complications-related costs decreased. Budget impact of ocriplasmin to the health plan was US$143,599 over 2 years or US$0.0060 per-member per-month. Conclusion: Ocriplasmin was projected to be minimally cost-additive at US$0.0060 per-member per-month over 2 years.

Using spectral-domain optical coherence tomography to evaluate the type and thickness of interdigitation zone band in adult Chinese

To study types and thickness of interdigitation zone band in adult Chinese subjects, we conducted a cross-sectional study. The population-based Beijing Eye Study 2011 included 3468 individuals with a mean age of 64.6 ± 9.8 years. 263 people (263eyes) with a mean age of 64.8 years were randomly selected cases without macular diseases included in the study. A detailed ophthalmic examination was performed including SD-OCT for measurement of the thickness of interdigitation zone band. There are two types of interdigitation zone band; the type1 which can distinguish RPE–BM complex in 170 eyes; and the Type 2 which the two layers merged involved 93 eyes. In type1, the mean thickness of the interdigitation zone band was significantly thicker in the foveal center (16.46 ± 2.92 μm), then nasal macular region (16.19 ± 2.69 μm), temporal macular region (15.73 ± 2.68 . μm), superior region (15.72 ± 2.70 μm), and inferior macular region (14.84 ± 2.63 μm) (P all < 0.05). And the mean thickness of the interdigitation zone band in the foveal center associated with the subfoveal choroidal thickness (P = 0.025) and level of education (P = 0.033). The increase in the thickness of the interdigitation zone band may play a role in the pathophysiologic features of various age-related ocular conditions.

Blood platelet and serum bilirubin in the diagnosis of central serous chorioretinopathy

Diagnostic value of blood platelet (PLT) and serum total bilirubin (TBIL) for central serous chorioretinopathy (CSC) was investigated. A total of 537 patients with CSC and 182 people with normal physical conditions were selected from June 2012 to August 2016. The 537 patients included 294 males and 243 females with an average age of 45.5±17.8 years, and all patients were treated in the Department of Ophthalmology of Yantai Hospital of Traditional Chinese Medicine and the Department of Ophthalmology of Yantai Liuhuangding Hospital. Clinical data of the patients were retrospectively analyzed. The 182 people with normal physical conditions included 103 males and 79 females with an average age of 43.6±15.2 years, and they were set as the control group. PLT and TBIL tests at admission and after treatment were collected and compared between CSC and the control group to analyze the diagnostic values of PLT and TBIL for CSC. PLT level in the CSC group was significantly higher than that in the control group, but TBIL level in the CSC group was significantly lower than that in the control group (p<0.05). Linear correlation analysis showed that PLT was a risk factor for CSC, and TBIL was a protective factor for CSC. The sensitivity of PLT and TBIL in diagnosis of CSC was 75.2 and 72.7%, respectively, and the specificity of PLT and TBIL in diagnosis of CSC was 65.8 and 63.3%, respectively. PLT of CSC patients was significantly higher than that of the control group, and TBIL of CSC patients was significantly lower than that of the control group, but they both gradually reduced to normal levels after treatment, which can be regarded as the index for the clinical diagnosis of CSC in the future.

Influence of the Vitreoretinal Interface on the Treatment with Anti-VEGF for Exudative Age-Related Macular Degeneration

PURPOSE

To investigate the influence of the vitreoretinal interface on the outcomes of different ranibizumab regimens for exudative age-related macular degeneration.

METHODS

We conducted a retrospective subanalysis of 2 prospective clinical trials. Patients were treated with ranibizumab for 12 months according to 3 different regimens: pro-re-nata (PRN), treat and extend (T&amp;E), and monthly. Vitreoretinal interface was assessed for absence (group ON) or presence (group OFF) of posterior vitreous detachment (PVD).

RESULTS

We included 64 eyes from 64 patients. Visual improvement was poorer for group ON (0.3 ± 10.7 letters) than for group OFF (9.2 ± 13.3; p = 0.007). A significant difference in letters of improvement between groups was observed in the PRN cohort (ON: -5.0 ± 12.9; OFF: 11.4 ± 11.9; p = 0.003), but not in the cohorts with monthly (ON: 5.7 ± 7.8; OFF: 7.9 ± 15.2; p = 0.735) or T&amp;E (ON: 4.3 ± 4.3; OFF: 7.8 ± 11.1; p = 0.424) treatment.

CONCLUSION

The negative impact of absence of PVD is regimen dependent, with monthly dosing providing similar outcomes to PVD patients. In the absence of PVD (group ON), PRN should be avoided, and T&amp;E might be an alternative.

SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY FINDINGS AND VISUAL OUTCOME AFTER TREATMENT FOR VITREOMACULAR TRACTION

PURPOSE

To evaluate the capacity of spectral domain optical coherence tomography macular findings to predict best-corrected visual acuity (BCVA) outcomes after treatment for symptomatic vitreomacular traction.

METHODS

This consecutive, retrospective study included 24 patients (29 eyes) who experienced vitreomacular traction release with pneumatic vitreolysis (n = 9), intravitreal ocriplasmin (n = 6), or pars plana vitrectomy (n = 14). Preoperative and postoperative spectral domain optical coherence tomography images were used to determine the cone outer segment tips (COST) line, inner segment/outer segment line, and other frequently used features. Correlations between optical coherence tomography findings and BCVA were determined using regression analyses.

RESULTS

Postoperative BCVA was correlated with length of the COST line and inner segment/outer segment line defects at 1, 3, 6, and 12 months postoperatively (P < 0.05) by simple linear regression analysis. However, multivariable regression analysis showed that only length of the COST line defect was significantly correlated with BCVA preoperatively and postoperatively (P < 0.05). Postoperative BCVA improvement at 12 months was significantly correlated with preoperative length of the COST line defect (P < 0.01).

CONCLUSION

Recovery of the COST line and inner segment/outer segment line defects as observed by spectral domain optical coherence tomography is positively correlated with visual acuity improvement after successful vitreomacular traction treatment. Best-corrected visual acuity improvement may be predicted using the length of the preoperative COST line defect.

Secondary Epiretinal Membrane After Trabeculectomy

PURPOSE

To determine the frequency of epiretinal membranes (ERM) in eyes with primary open-angle glaucoma subjected to trabeculectomy.

METHODS

We conducted a retrospective study on patients subjected to trabeculectomy with at least a 6-month follow-up. Ophthalmologic examination and spectral-domain optical coherence tomography (SD-OCT) were analyzed. Eyes with previous surgical or laser treatments or other pathologies (other than glaucoma and ERM) were excluded.

RESULTS

A total of 50 eyes (40 patients) were included in this study. The mean follow-up time after surgery was 27.8 months. After surgery, 9 eyes (18%) had preretinal macular fibrosis and 19 eyes (38%) had cellophane macular reflex. Of the 16 eyes with a preoperative macular SD-OCT, 3 (18.8%) developed ERM and 4 (25%) progressed from cellophane macular reflex to preretinal macular fibrosis, after surgery. The ERM frequency did not differ significantly between eyes subjected to trabeculectomy with or without the use of antimetabolites (P=0.08), or between eyes subjected to simple or combined surgery (phacotrabeculectomy) (P=0.09).

CONCLUSION

Trabeculectomy may predispose one to the appearance and progression of ERM. Further studies are needed to clarify this intriguing relation.

HYPERREFLECTIVE FOCI AS AN INDEPENDENT VISUAL OUTCOME PREDICTOR IN MACULAR EDEMA DUE TO RETINAL VASCULAR DISEASES TREATED WITH INTRAVITREAL DEXAMETHASONE OR RANIBIZUMAB

PURPOSE

To evaluate the potential role of hyperreflective foci (HF) in predicting visual outcome in patients undergoing treatment for macular edema due to retinal vascular diseases.

METHODS

Data and images of 92 patients with macular edema due to diabetes mellitus or branch retinal vein occlusion, treated with either intravitreal dexamethasone implant or ranibizumab, were analyzed. All patients underwent best-corrected visual acuity measurement, slit-lamp examination, spectral domain optical coherence tomography at baseline and at all time points of the follow-up (Month 1, 2, 3, 6, and 9). Generalized least squares random effects linear or logistic regression analysis was used to investigate potential factors associated with the final best-corrected visual acuity and number of HF, respectively.

RESULTS

Increasing age (P < 0.001), central retinal thickness (P < 0.001), number of HF (P = 0.028), presence of subretinal fluid (P < 0.001), intraretinal fluid (P < 0.001), intraretinal cysts (P < 0.001), and disruption of ellipsoid zone/external limiting membrane (P < 0.001) were significantly associated with poorer visual outcome. Factors associated with HF were increasing central retinal thickness (P = 0.003), presence of subretinal fluid (P = 0.049), intraretinal fluid (P = 0.002), cysts (P = 0.015), and disruption of ellipsoid zone (P = 0.047). No significant differences in change in best-corrected visual acuity, central retinal thickness, and HF were observed between the two treatment groups.

CONCLUSION

Hyperreflective foci are associated with poorer visual outcome in patients with macular edema due to retinal vascular diseases. Similar reductions in HF are achieved by intravitreal steroid and anti-vascular endothelial growth factor agent.

Relationship Between Retinal Perfusion and Retinal Thickness in Healthy Subjects: An Optical Coherence Tomography Angiography Study

Purpose

To investigate the relationship between retinal perfusion and retinal thickness in the peripapillary and macular areas of healthy subjects.

Methods

Using spectral-domain optic coherence tomography and split-spectrum amplitude decorrelation angiography (SSADA) algorithm, retinal perfusion and retinal thicknesses in the macular and peripapillary areas were measured in healthy volunteers, and correlations among these variables were analyzed.

Results

Overall, 64 subjects (121 eyes) including 28 males and 36 females with a mean ± SD age of 38 ± 13 years participated. Linear mixed-models showed that vessel area density was significantly correlated with the inner retinal thickness (from the inner limiting membrane to the outer border of the inner nucleus layer; P < 0.05), but not with the thickness of the full retina (P > 0.05) in the parafoveal area. The area of the foveal capillary-free zone was negatively correlated with the inner and full foveal thicknesses (all P < 0.001). In the peripapillary area, the vessel area density was positively correlated with the thickness of the retinal nerve fiber layer (P < 0.001).

Conclusions

In healthy subjects, retinal perfusion in small vessels was closely correlated with the thickness of the inner retinal layers in both the macular and peripapillary areas.

Evaluation of hyperreflective foci as a prognostic factor of visual outcome in retinal vein occlusion

AIM

To evaluate the potential role of hyperreflective foci (HF) as a prognostic indicator of visual outcome in patients with macular edema (ME) due to retinal vein occlusion (RVO).

METHODS

We retrospectively reviewed 50 eyes of 50 patients with ME due to ischemic central retinal vein occlusion (CRVO), non-ischemic CRVO and branch retinal vein occlusion (BRVO) who were treated with anti-vascular endothelial growth factor (anti-VEGF) at Beijing Tongren Eye Center from January 2013 to July 2016. All patients underwent best-corrected visual acuity (BCVA), spectral domain optical coherence tomography (SD-OCT) at baseline and follow-up. Such factors were evaluated and compared among three groups as baseline and final BCVA, central retinal thickness (CRT), external limiting membrane (ELM) status and the numbers of HF in different position. Multiple linear regression analysis was employed to analyze the relationship between baseline HF and final BCVA. Changes of HF before and after treatment were evaluated too.

RESULTS

Among three groups, HF could be located in each retinal layers, as well as in vitreous cavity. The mean HF in outer retinal layer (ORL) at baseline was 5.29±8.48 in ischemic CRVO with intact ELM, 1.93±2.76 in non-ischemic CRVO, and 1.75±2.05 in BRVO. With disrupted ELM, the mean HF in ORL increased. There was statistically difference of HF in ORL between intact and disrupted ELM. The numbers of HF in ORL were associated with poor visual outcome among three groups. However, HF in inner retinal layer (IRL) and vitreous cavity were not associated with poor visual outcome. Meanwhile, the baseline HF in ORL and vitreous cavity reduced significantly in non-ischemic CRVO and BRVO after anti-VEGF treatment.

CONCLUSION

The numbers of HF in ORL are prognostic factors associated with the final BCVA in patients with ME due to RVO after anti-VEGF treatment.

The Distribution of Macular Thickness and Its Determinants in a Healthy Population

PURPOSE

To determine the distribution of macular thickness in a healthy Iranian population aged 45-69 years and its association with certain determinants.

METHODS

All participants underwent optometric examinations including measurement of uncorrected and corrected visual acuity, objective refraction by retinoscopy, and subjective refraction. Subsequently, all participants underwent slit-lamp biomicroscopy followed by fundus examination through direct and indirect ophthalmoscopy, and optical coherence tomography (OCT) imaging under pupil dilation.

RESULTS

Mean central macular thickness was 255.4 µm (95% confidence interval, CI, 254.5-256.3 µm), average inner macular thickness was 316.5 µm (95% CI 315.9-317.1 µm), average outer macular thickness was 275.3 µm (95% CI 274.8-275.8 µm), and overall average thickness was 278.6 µm (95% CI 278.1-279.1 µm). A linear multiple regression model showed that all indexes were significantly larger in male participants (p < 0.001). Central macular thickness increased with age (coef = 0.25, p < 0.001) while overall, inner and outer macular thickness decreased with age (coef = -0.18, -0.15, -0.19, respectively, all p < 0.001). Central and inner macular thickness had a positive correlation (coef = 3.8, 2.6, respectively, both p < 0.001) and outer macular thickness had a negative correlation (coef = -1.6, p < 0.001) with axial length.

CONCLUSION

Age, sex, refractive error, axial length, and keratometry were found to be associated with macular thickness. These factors should be taken into account when interpreting macular thickness measurements with spectral-domain OCT.

Minification of fundus optical coherence tomographic images in gas-filled eye

BACKGROUND

Optical coherence tomography (OCT) is being used increasingly to evaluate and manage a variety of retinal diseases, but not much is known about the minification of the OCT images in gas-filled eyes. The purpose of this study was to investigate the effect of gas-filled eyes on the size of the OCT images.

METHODS

This was retrospective case series of 81 consecutive eyes of 79 patients who had macular hole surgery between April 2012 and September 2014. Images of the optic disc were taken with a spectral domain-OCT instrument 2 days after surgery in gas-filled, pseudophakic eyes and from the same eyes but fluid-filled one month after the surgery. The vertical length, horizontal width, and the area of the optic disc were measured in the OCT images.

RESULTS

Clear images were obtained from 50 eyes of 49 patients (mean age 66.4 ± 5.9 years). The mean vertical length and mean horizontal width of the optic disc in the gas-filled eyes were about 25 % shorter than that of fluid-filled eyes (vertical, 1213.8 ± 170.5 and 1650.6 ± 195.9 μm, P < 0.01; horizontal, 1169.4 ± 143.1 and 1526.4 ± 219.9 μm, P < 0.01). The mean area of the optic disc was 1.12 ± 0.34 mm(2) in gas-filled eyes which was significantly smaller than that in fluid-filled eyes (1.88 ± 0.37 mm(2)) by 40.4 %.

CONCLUSIONS

The fundus images of gas-filled eyes are significantly smaller than that in the same fluid-filled eyes. The minification of the OCT images should be considered when analyzing images obtained from gas-filled eyes.

TRIAL REGISTRATION

TRIAL REGISTRATION NUMBER

UMIN000007517 . Date of registration: 3/21/2012.

Macular Surgery Using Intraoperative Spectral Domain Optical Coherence Tomography

PURPOSE

To report the use of intraoperative spectral domain optical coherence tomography (SD-OCT) for detecting anatomical changes during macular surgery.

METHODS

In a consecutive case series, 32 eyes of 32 patients undergoing concurrent pars plana vitrectomy and intraoperative SD-OCT for macular hole (MH), epiretinal membrane (ERM) and vitreomacular traction (VMT) were enrolled. Intraoperative changes in retinal thickness and dimensions of the macular hole were measured in patients with ERM and VMT following surgical manipulation using a hand-held SD-OCT device (iVue, Optovue Inc., Fremont, CA, USA).

RESULTS

SD-OCT images of sixteen eyes with macular hole were subjected to quantitative and qualitative analysis. All MH dimensions remained stable during consecutive stages of surgery except for MH apex diameter, which showed a significant decrease after internal limiting membrane (ILM) peeling (P=0.025). Quantitative analysis of ten patients with ERM showed a significant decrease in retinal thickness after membrane removal (P=0.018) which did not remain significant until the end of the procedure (P=0.8). In three cases, subretinal fluid was formed after ILM peeling. Quantitative analysis of five patients with VMT showed a decrease in retinal thickness during consecutive steps of the surgery, although these changes were not significant. In two cases, subretinal fluid was formed after ILM peeling.

CONCLUSION

Intraoperative SD-OCT is a useful imaging technique which provides vitreoretinal surgeons with rapid awareness of changes in macular anatomy during surgery and may therefore result in better anatomical and visual outcomes.

Correlation between foveal interdigitation zone band defect and visual acuity after surgery for macular pseudohole

PURPOSE

To determine the correlation between the integrity of the foveal microstructures and the best-corrected visual acuity (BCVA) after pars plana vitrectomy for a macular pseudohole.

METHODS

Thirty-one eyes of 31 patients with a macular pseudohole underwent vitrectomy with internal limiting membrane removal. The foveal area was examined by spectral domain optical coherence tomography preoperatively and postoperatively. The correlations between the BCVA and the lengths of the photoreceptor interdigitation zone (IZ), the ellipsoid zone, and the external limiting membrane band defects, and central foveal thickness were determined.

RESULTS

The BCVA improved significantly and the length of the IZ band defect decreased significantly after the surgery. Simple linear regression analyses showed that the BCVA was significantly correlated with the length of the IZ band defect preoperatively and also at 1 to 12 months postoperatively (P < 0.001 for all). The BCVA was not significantly correlated with the length of the ellipsoid zone, external limiting membrane band defect, and the central foveal thickness.

CONCLUSION

The significant correlation between the length of the foveal IZ band defect and the BCVA preoperatively and postoperatively indicates that the foveal IZ band is related to the visual recovery in patients with macular pseudohole.

Quantitative Analysis of Mouse Retinal Layers Using Automated Segmentation of Spectral Domain Optical Coherence Tomography Images

PURPOSE

Quantification of retinal layers using automated segmentation of optical coherence tomography (OCT) images allows for longitudinal studies of retinal and neurological disorders in mice. The purpose of this study was to compare the performance of automated retinal layer segmentation algorithms with data from manual segmentation in mice using the Spectralis OCT.

METHODS

Spectral domain OCT images from 55 mice from three different mouse strains were analyzed in total. The OCT scans from 22 C57Bl/6, 22 BALBc, and 11 C3A.Cg-Pde6b⁺Prph2^Rd2 /J mice were automatically segmented using three commercially available automated retinal segmentation algorithms and compared to manual segmentation.

RESULTS

Fully automated segmentation performed well in mice and showed coefficients of variation (CV) of below 5% for the total retinal volume. However, all three automated segmentation algorithms yielded much thicker total retinal thickness values compared to manual segmentation data (P < 0.0001) due to segmentation errors in the basement membrane.

CONCLUSIONS

Whereas the automated retinal segmentation algorithms performed well for the inner layers, the retinal pigmentation epithelium (RPE) was delineated within the sclera, leading to consistently thicker measurements of the photoreceptor layer and the total retina.

TRANSLATIONAL RELEVANCE

The introduction of spectral domain OCT allows for accurate imaging of the mouse retina. Exact quantification of retinal layer thicknesses in mice is important to study layers of interest under various pathological conditions.

Correlation between Visual Acuity, Inner Segment/Outer Segment Junction, and Cone Outer Segment Tips Line Integrity in Uveitic Macular Edema

PURPOSE

To investigate the correlation between best-corrected visual acuity (BCVA), the foveal inner segment/outer segment (IS/OS) junction or ellipsoid portion of inner segment (EPIS/ellipsoid zone), and the cone outer segment tips (COST) line or interdigitation zone integrity in eyes with uveitic macular edema (ME).

METHOD

A retrospective observational study involving all patients from January 2012 to December 2013 with uveitic ME was performed. All patients underwent BCVA using Snellen charts spectral-domain optical coherence tomography (SD-OCT) examination using Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany).

RESULTS

Fifty-two eyes from 45 patients were included in this study. Multivariate analysis showed a negative correlation between BCVA and the central retinal subfield thickness (CST), the cystoid pattern of edema, and the interdigitation zone interruption. Univariate logistic analysis showed a strong correlation between the ellipsoid zone and the interdigitation zone integrity.

CONCLUSIONS

The ellipsoid zone defect, the interdigitation zone interruption, and the CST are correlated with poor vision. Visual acuity is also strongly affected by the cystoid pattern. The interdigitation zone integrity appears to be the most important factor in the visual prognosis of uveitic ME.

The causes of hyperreflective dots in optical coherence tomography excluding diabetic macular edema and retinal venous occlusion§

Purpose :

To investigate the causes of hyperreflective dots (HRDs) in spectral domain optical coherence tomography (OCT) excluding diabetic macular edema (DME) and RVO (retinal vein occlusion).

Patients and Methods :

The medical records of 56 patients with HRDs documented by OCT were reviewed retrospectively. The patients with DME and RVO were excluded from the study in order to prevent misdiagnosing hard exudates or HRDs. The causes, unilaterality or bilaterality of HRD and demographic properties of the patients with HRD were evaluated.

Results :

Sixty four eyes of 56 patients having HRDs were included in this study. Of the patients with HRD, 17 (30.36%) were women and 39 (69.64%) were men. The ages of patients were between 13 to 84 years (median 60.18 years). The causes of HRD were as follows: papilledema in 4 eyes (6.25%), active neovascular age related macular degeneration (AMD) in 33 eyes (51.56%), familial dominant drusen in 2 eyes (3.13%), central serous chorioretinopathy in 19 eyes (29.69%) and commotio retina in 2 eyes (3.13%), choroidal folds in one eye (1.56%), branch retinal artery occlusion in one eye (1.56%), central retinal artery occlusion in one patient (1.56%) and Best vitelliform macular dystrophy in one eye (1.56%). The most common cause of HRD was AMD. The causes of HRDs in both eyes were AMD and papilledema.

Conclusion :

The most common causes of HRDs excluding DME and RVO seem as active exudative AMD. The presence of HRDs in retinal diseases might affect the decisions and the results of the treatment and the prognosis of diseases.

Foveal contour changes following surgery for idiopathic epiretinal membrane

PURPOSE

We evaluated the change in foveal contour in eyes with idiopathic epiretinal membrane (ERM) before and four months following pars plana vitrectomy with internal limiting and epiretinal membrane peeling, and correlated foveal contour with best corrected visual acuity (BCVA) and optical coherence tomography (OCT) parameters.

METHODS

Retrospective chart review of consecutive patients undergoing surgery with pre- and postoperative OCT. Foveal contour grading was devised according to the thickness of the fovea relative to the surrounding macula from OCT radial line scans: Grade 0, foveal depression relative to surrounding macula; Grade 1, relative flatness; and Grade 2, fovea thicker than surrounding macula. Baseline and follow-up grades were compared for change and correlated with BCVA, central retinal thickness (CRT), central subfield thickness (CST), central subfield volume (CSV), and integrity of the ellipsoid zone (EZ).

RESULTS

Among 41 eyes of 41 patients, mean follow-up was 125 days. No eyes were Grade 0 at baseline; 7 of 41 eyes were Grade 0 at follow-up. Baseline Grade 1 eyes improved CRT (P < 0.001), CST (P < 0.001), CSV (P = 0.002), and BCVA (P = 0.022). Baseline Grade 2 eyes improved CRT (P < 0.001), CST (P < 0.001), and CSV (P < 0.001), but not BCVA (P = 0.369).

CONCLUSIONS

We developed a novel foveal contour grading method to assess retinal contour in ERM eyes before and after surgery. In eyes with ERM and no foveal depression, the majority did not regain foveal depression following surgery even though retinal thickness improved.

Spectral-domain optical coherence tomography for macular edema

Optical coherence tomography (OCT) is a rapid noncontact method that allows in vivo imaging of the retina and it has become an important component in clinical practice. OCT is a useful ancillary tool for assessing retinal diseases because of its ability to provide cross-sectional retinal images and quantitatively analyze retinal morphology. The introduction of spectral-domain OCT provided major improvements in image acquisition speed and image resolution. Future studies will address how these major technologic advances will impact the use of OCT in research and clinical practice.

Spectral-domain optical coherence tomography of the rodent eye: highlighting layers of the outer retina using signal averaging and comparison with histology

Spectral-Domain Optical Coherence Tomography (SD-OCT) is a widely used method to observe retinal layers and follow pathological events in human. Recently, this technique has been adapted for animal imaging. This non-invasive technology brings a cross-sectional visualization of the retina, which permits to observe precisely each layer. There is a clear expansion of the use of this imaging modality in rodents, thus, a precise characterization of the different outer retinal layers observed by SD-OCT is now necessary to make the most of this technology. The identification of the inner strata until the outer nuclear layer has already been clearly established, while the attribution of the layers observed by SD-OCT to the structures corresponding to photoreceptors segments and retinal pigment epithelium is much more questionable. To progress in the understanding of experimental SD-OCT imaging, we developed a method for averaging SD-OCT data to generate a mean image allowing to better delineate layers in the retina of pigmented and albino strains of mice and rats. It allowed us to locate precisely the interface between photoreceptors and retinal pigment epithelium and to identify unambiguously four layers corresponding to the inner and outer parts of photoreceptors segments. We show that the thickness of the various layers can be measured as accurately in vivo on SD-OCT images, than post-mortem by a morphometric analysis of histological sections. We applied SD-OCT to different models and demonstrated that it allows analysis of focal or diffuse retinal pathological processes such as mutation-dependant damages or light-driven modification of photoreceptors. Moreover, we report a new method of combined use of SD-OCT and integration to quantify laser-induced choroidal neovascularization. In conclusion, we clearly demonstrated that SD-OCT represents a valuable tool for imaging the rodent retina that is at least as accurate as histology, non-invasive and allows longitudinal follow-up of the same animal.

Usefulness of optical coherence tomography to detect central serous chorioretinopathy in monkeys

Many systemic drugs can induce ocular toxicity and several ocular side-effects have been identified in clinical studies. However, it is difficult to detect ocular toxicity in preclinical studies because of the lack of appropriate evaluation methods. Optical coherence tomography (OCT) is useful because it can provide real-time images throughout a study period, whereas histopathology only provides images of sacrificed animals. Using OCT alongside histopathology, attempts were made to find effective approaches for screening of drug-induced ocular toxicity in monkeys. Such approaches could be used in preclinical studies prior to human trials. Six male cynomolgus monkeys (Macaca fascicularis Raffles) were orally administered one of six candidate MAPK/ERK kinase (MEK) inhibitors. Central serous chorioretinopathy, a known side-effect of such inhibitors, was identified in four monkeys by OCT. Artifacts generated during tissue processing meant that histopathology could not detect edematous changes. Thus, OCT is a useful tool to detect ocular toxicity which cannot be detected by histopathology in preclinical studies.

"Floater scotoma" demonstrated on spectral-domain optical coherence tomography and caused by vitreous opacification

Patients with prominent vitreous opacities may demonstrate a characteristic shadowing on the volume-scanning protocols using spectral-domain optical coherence tomography. The authors present five cases of this characteristic shadowing artifact. This finding may be useful in objectively documenting the status of vitreous opacification and verifying the patient's complaint of symptomatic floaters, a so-called "floater scotoma".

[Comparison of thickness values in nine macular subfields using time-domain and spectral-domain optical coherence tomography]

AIM

To compare macular thickness measurements with spectral-domain (Cirrus HD-OCT) and time-domain (StratusOCT) optical coherence tomography.

METHOD

Macular thickness was measured in nine ETDRS subfields in the same eye of 20 healthy subjects using both instruments. Using Cirrus HD-OCT both the Macular Cube 512×128 and Macular Cube 200×200 protocol, using StratusOCT the Fast Macular Thickness Map protocol was performed. Reproducibility of all three measurement series was assessed and the average of the measurement series was compared on each field.

RESULTS

Measurement values obtained by StratusOCT were significantly lower than those obtained by Cirrus HD-OCT (p<0.001) in all subfields. Correlation coefficient between the results obtained by the two protocols of Cirrus HD-OCT was 0.977.

CONCLUSIONS

By using Cirrus HD-OCT we could observe better repeatability than with StratusOCT. Using Cirrus HD-OCT significantly higher measurement values could be obtained in all subfields than those measured with Stratus. Using different OCT instruments we get significantly different values, therefore care needs to be taken when comparing data.

Epiretinal membranes in patients with uveitis: morphological and functional analysis with spectral domain optical coherence tomography

Purpose. To correlate the uveitic epiretinal membrane (ERM) features using spectral-domain optical coherence tomography (SD-OCT) with visual acuity (VA). Methods. Forty-one eyes of 32 patients were included in this retrospective study. SD-OCT was performed in all patients and data were collected at the time of ERM diagnosis and at the final visit. Both best corrected visual acuity (BCVA) and ERM thickness were correlated with the morphological and clinical features. Results. Final BCVA was positively correlated with male sex (P = 0.0055) and the focal pattern of ERM attachment (P = 0.031) and negatively correlated with IS/OS photoreceptor junction disruption (P = 0.042). BVCA change showed a positive correlation with the age of ERM onset (P = 0.056) but a negative correlation with IS/OS photoreceptor disruption at the ERM diagnosis (P = 0.029) and the increase of central subfield thickness (CST) (P = 0.95). Final ERM thickness correlated with the duration of uveitis (P = 0.0023) and the duration of ERM (P = 1.15  e-05). During the follow-up, ERM thickening correlated with male sex (P = 0.042), posterior uveitis (P = 0.036), uveitis duration (P = 0.026), and broad attachment pattern (P = 0.052). Conclusions. In the uveitic ERM, VA negatively correlates with IS/OS photoreceptor junction disruption and the increase of CST. ERM thickness is influenced by longer duration of both uveitis and ERM.

Macular edema in the era of spectral-domain optical coherence tomography

The development of spectral-domain optical coherence tomography (OCT) allows for the highest commercially available resolution of in vivo retinal anatomic details to date. The ability to see the macula with ever increasing detail is dramatically improving our understanding of the pathogenesis of retinal disease. However, the only prospective study that partially evaluated spectral-domain OCT versus time-domain OCT failed to show any clinical benefit of increased OCT resolution. Clinical outcomes, eg, best-corrected visual acuity, central macular thickness and number of injections, with “newer” OCT technologies remain an unproven advantage.

Characteristic findings of optical coherence tomography in retinal angiomatous proliferation

Purpose

To identify the unique pathologic findings of retinal angiomatous proliferation (RAP) in optical coherence tomography (OCT).

Methods

Retrospectively, 29 eyes of 25 patients with age-related macular degeneration and complicated RAP were analyzed. All 29 eyes had choroidal neovascularization (CNV) in the area of pigment epithelial detachment (PED) or adjacent to it, which was visible with fluorescein angiography or indocyanine green angiography. Cross-sectional images were obtained by OCT scanning through the CNV lesions.

Results

Six distinctive findings of OCT included drusen (100%), inner retinal cyst (80%), outer retinal cyst (68%), fibrovascular PED (84%), serous retinal detachment (40%), and PED (68%).

Conclusions

Through analysis of OCT findings, we revealed six different types of lesions distinctive of RAP which may provide helpful diagnostic information for subsequent treatment and predicting the prognosis of RAP.