DIFFERENTIAL DIAGNOSIS OF MACULAR EDEMA OF DIFFERENT PATHOPHYSIOLOGIC ORIGINS BY SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY

Exploration on OCT biomarker candidate related to macular edema caused by diabetic retinopathy and retinal vein occlusion in SD-OCT images

To improve the understanding of potential pathological mechanisms of macular edema (ME), we try to discover biomarker candidates related to ME caused by diabetic retinopathy (DR) and retinal vein occlusion (RVO) in spectral-domain optical coherence tomography images by means of deep learning (DL). 32 eyes of 26 subjects with non-proliferative DR (NPDR), 77 eyes of 61 subjects with proliferative DR (PDR), 120 eyes of 116 subjects with branch RVO (BRVO), and 17 eyes of 15 subjects with central RVO (CRVO) were collected. A DL model was implemented to guide biomarker candidate discovery. The disorganization of the retinal outer layers (DROL), i.e., the gray value of the retinal tissues between the external limiting membrane (ELM) and retinal pigment epithelium (RPE), the disrupted and obscured rate of the ELM, ellipsoid zone (EZ), and RPE, was measured. In addition, the occurrence, number, volume, and projected area of hyperreflective foci (HRF) were recorded. ELM, EZ, and RPE are more likely to be obscured in RVO group and HRFs are observed more frequently in DR group (all P ≤ 0.001). In conclusion, the features of DROL and HRF can be possible biomarkers related to ME caused by DR and RVO in OCT modality.

Optical Coherence Tomography Biomarkers in Predicting Treatment Outcomes of Diabetic Macular Edema after Ranibizumab Injections

Background and Objectives: The identification of possible biomarkers that can predict treatment response among DME eyes is important for the individualization of treatment plans. We investigated optical coherence tomography (OCT)-based biomarkers that may predict the one-year real-life outcomes among diabetic macular edema (DME) eyes following treatment by intravitreal ranibizumab (IVR) injections. Materials and Methods: A total of 65 eyes from 35 treatment-naïve patients with DME treated with ranibizumab injection were recruited. Best-corrected visual acuity (BCVA), central retinal thickness (CRT), intraocular pressure (IOP), and OCT scans were retrospectively recorded at baseline before treatment and at 3 months, 6 months, and 12 months after treatment. The OCT scans were evaluated for biomarkers of interest, which included central retinal thickness (CRT), amount and locations of hyperreflective foci (HRF), subretinal fluid (SRF), intraretinal cysts (IRC), large outer nuclear layer cyst (LONLC), ellipsoid zone disruption (EZD), disorganization of retinal inner layers (DRIL), hard exudates (HE), epiretinal membrane (ERM), and vitreomacular interface (VMI). Correlations between these OCT biomarkers and outcome measures (visual and structural) were statistically analyzed. Results: A total of 65 eyes from 35 patients with DME were enrolled. The mean age was 64.2 ± 10.9 years old. Significant improvement in terms of mean BCVA (p < 0.005) and mean CRT was seen at final follow-up compared to baseline. The biomarkers of DRIL, LONLC, and SRF were found to be predictive for at least 50 μm CRT reduction after treatment (with odds ratio of 8.69, 8.5, and 17.58, respectively). The biomarkers of IRC, LONLC, and SRF were predictive for significant improvement in terms of BCVA and CRT after treatment. Finally, the number of HRF was predictive for both BCVA improvement and a CRT reduction of less than 100 μm after treatment. No serious complications were reported during the study. Conclusion: Our study demonstrated the utility of OCT biomarkers as therapeutic predictors of ranibizumab treatment among DME eyes.

Etiology of Macular Edema Defined by Deep Learning in Optical Coherence Tomography Scans

Purpose

To develop an automated method based on deep learning (DL) to classify macular edema (ME) from the evaluation of optical coherence tomography (OCT) scans.

Methods

A total of 4230 images were obtained from data repositories of patients attended in an ophthalmology clinic in Colombia and two free open-access databases. They were annotated with four biomarkers (BMs) as intraretinal fluid, subretinal fluid, hyperreflective foci/tissue, and drusen. Then the scans were labeled as control or ocular disease among diabetic macular edema (DME), neovascular age-related macular degeneration (nAMD), and retinal vein occlusion (RVO) by two expert ophthalmologists. Our method was developed by following four consecutive phases: segmentation of BMs, the combination of BMs, feature extraction with convolutional neural networks to achieve binary classification for each disease, and, finally, multiclass classification of diseases and control images.

Results

The accuracy of our model for nAMD was 97%, and for DME, RVO, and control were 94%, 93%, and 93%, respectively. Area under curve values were 0.99, 0.98, 0.96, and 0.97, respectively. The mean Cohen's kappa coefficient for the multiclass classification task was 0.84.

Conclusions

The proposed DL model may identify OCT scans as normal and ME. In addition, it may classify its cause among three major exudative retinal diseases with high accuracy and reliability.

Translational Relevance

Our DL approach can optimize the efficiency and timeliness of appropriate etiological diagnosis of ME, thus improving patient access and clinical decision making. It could be useful in places with a shortage of specialists and for readers that evaluate OCT scans remotely.

Comparison of hyperreflective foci in macular edema secondary to multiple etiologies with spectral-domain optical coherence tomography: An observational study

Background

Hyperreflective foci (HRF) features in macular edema associated with different etiologies may indicate the disease pathogenesis and help to choose proper treatment. The goal of this study is to investigate the retinal microstructural features of macular edema (ME) secondary to multiple etiologies with spectral-domain optical coherence tomography (SD-OCT) and analyze the origin of HRF in ME.

Methods

This was a retrospective study. SD-OCT images were reviewed to investigate macular microstructural features such as the number and distribution of HRF and hard exudates and the internal reflectivity of the cysts. The differences in microstructural features between groups and the correlations between the number of HRF and other parameters were analyzed.

Results

A total of 101 eyes with ME from 86 diabetic (diabetic macular edema, DME) patients, 51 eyes from 51 patients with ME secondary to branch retinal vein occlusion (branch retinal vein occlusion-macular edema, BRVO-ME), 59 eyes from 58 central retinal vein occlusion (central retinal vein occlusion-macular edema, CRVO-ME) patients, and 26 eyes from 22 uveitis (uveitic macular edema, UME) patients were included in this study. The number of HRF, the frequency of hard exudates and the enhanced internal reflectivity of the cysts were significantly different among the groups. The number of HRF in the DME group was significantly higher than that in the other groups (all P < 0.05). The frequency of hard exudates and enhanced internal reflectivity of the cysts in the DME group were significantly higher than ME secondary to other etiologies (all P < 0.001). Within the DME group, the number of HRF in the patients with hard exudates was significantly higher than that in the patients without hard exudates (P < 0.001).

Conclusion

HRF detected with SD-OCT were more frequent in DME patients than in BRVO-ME, CRVO-ME, or UME patients. The occurrence of HRF was correlated with the frequency of hard exudates. HRF may result from the deposition of macromolecular exudates in the retina, which is speculated to be a precursor of hard exudates.

The Role of Intravitreal Corticosteroids in the Treatment of DME: Predictive OCT Biomarkers

This work aims to summarize predictive biomarkers to guide treatment choice in DME. Intravitreal anti-VEGF is considered the gold standard treatment for centers involving DME, while intravitreal steroid treatment has been established as a second-line treatment in DME. However, more than 1/3 of the patients do not adequately respond to anti-VEGF treatment despite up to 4-weekly injections. Not surprisingly, insufficient response to anti-VEGF therapy has been linked to low-normal VEGF levels in the serum and aqueous humor. These patients may well benefit from an early switch to intravitreal steroid treatment. In these patients, morphological biomarkers visible in OCT may predict treatment response and guide treatment decisions. Namely, the presence of a large amount of retinal and choroidal hyperreflective foci, disruption of the outer retinal layers and other signs of chronicity such as intraretinal cysts extending into the outer retina and a lower choroidal vascular index are all signs suggestive of a favorable treatment response of steroids compared to anti-VEGF. This paper summarizes predictive biomarkers in DME in order to assist individual treatment decisions in DME. These markers will help to identify DME patients who may benefit from primary dexamethasone treatment or an early switch.

Peripapillary retinal nerve fiber layer thickness in patients with unilateral retinal vein occlusion

This study evaluated longitudinal changes in peripapillary retinal nerve fiber layer (pRNFL) thickness in eyes affected with branch and central retinal vein occlusion (BRVO and CRVO, respectively) and fellow eyes. This retrospective case-control study included patients with newly diagnosed unilateral BRVO (46 patients) or unilateral CRVO (27 patients). The control group included 48 patients without abnormal findings on the fundus examination. Global and all-sector pRNFL thicknesses were greater in eyes with BRVO and CRVO than in fellow eyes at baseline; however, at 24 months, this difference remained only in the temporal sector of eyes affected with CRVO. Although the global pRNFL thicknesses of the fellow eyes in the BRVO and CRVO groups decreased significantly at 24 months compared to baseline (p = 0.001 and p = 0.011, respectively), there was no significant difference in the normal control group (p = 0.824). The global, inferior temporal, and inferior nasal pRNFL thicknesses at 12 and 24 months were significantly lower in the fellow eyes of the CRVO group than in those of the BRVO and normal control groups. The fellow eyes of patients with BRVO and CRVO suffered a significant reduction in pRNFL thickness compared to normal controls, indicating that they are susceptible to pRNFL damage.

Quantifying frequency content in cross-sectional retinal scans of diabetics vs. controls

Purpose

To examine subtle differences in the structure of diabetic vs. control retinas.

Methods

Spectral-domain optical coherence tomography (SD-OCT) images were compared for the retinas of 33 diabetic subjects who did not have clinical evidence of diabetic macular edema and age-matched controls, with central macular thicknesses of 275 and 276 microns, respectively. Cross-sectional retinal images through the fovea, called B-scans, were analyzed for spatial frequency content. The B-scans were processed to remove and smooth the portions of the retinal image not within regions of interest in the retina. The remaining retinal images were then quantified using a Fast Fourier Transform (FFT) approach that provided amplitude as a function of spatial frequency.

Results

The FFT analysis showed that diabetic retinas had spatial frequency content with significantly higher power compared to control retinas particularly for a deeper fundus layer at mid-range spatial frequencies, ranging from p = 0.0030 to 0.0497 at 16.8 to 18.2 microns/cycle. There was lower power at higher spatial frequencies, ranging from p = 0.0296 and 0.0482 at 27.4 and 29.0 microns/cycle. The range of mid-range frequencies corresponds to the sizes of small blood vessel abnormalities and hard exudates. Retinal thickness did not differ between the two groups.

Conclusions

Diabetic retinas, although not thicker than controls, had subtle but quantifiable pattern changes in SD-OCT images particularly in deeper fundus layers. The size range and distribution of this pattern in diabetic eyes were consistent with small blood vessel abnormalities and leakage of lipid and fluid. Feature-based biomarkers may augment retinal thickness criteria for management of diabetic eye complications, and may detect early changes.

MICROSTRUCTURAL CHANGES IN CYSTOID MACULAR EDEMA IN RETINITIS PIGMENTOSA AFTER INTRAVITREAL DEXAMETHASONE IMPLANT INJECTION

PURPOSE

To evaluate microstructural changes in cystoid macular edema in retinitis pigmentosa after intravitreal dexamethasone implant injection.

METHODS

In an extended cohort of a randomized trial of intravitreal dexamethasone implant for the management of retinitis pigmentosa-associated cystoid macular edema, microstructural changes during six months after the treatment were evaluated using spectral-domain optical coherence tomography.

RESULTS

Forty-two eyes were included, and all had cystoid space in the inner nuclear layer (INL) at baseline. No eyes showed subretinal fluid, and 28.6% showed hyperreflective foci. Among 38 eyes with cystoid space both in the INL and outer nuclear layer/Henle's layer, 13 (34.2%) showed complete resolution and 12 (31.6%) showed cystoid space only in the INL at 2 months after injection, whereas others showed persistent cystoid space in both layers. After complete resolution, cystoid space recurrence was earlier in the INL than in the outer nuclear layer/Henle's layer. Multivariable analysis showed that greater cystoid space area in the INL and outer nuclear layer/Henle's layer, presence of macular leakage, and longer intact external limiting membrane at baseline were associated with greater cystoid space area decrease after the treatment.

CONCLUSION

Resolution and recurrence pattern of retinitis pigmentosa-associated cystoid macular edema after dexamethasone treatment showed that the INL is the primary layer of cystic change, and this suggests its pathogenesis is most likely caused by Müller cell dysfunction.

Evaluation of morphological characteristics of diabetic macular edema in patients with non-proliferative versus proliferative diabetic retinopathy: a spectral-domain optical coherence tomography study

PURPOSE

To evaluate the morphological characteristics in patients with diabetic macular edema (DME), either with co-existent non-proliferative diabetic retinopathy (NPDR) or with PDR.

METHODS

Retrospective study includes 138 treatment naïve patients with DME, either with NPDR (n = 96) or in combination with PDR (n = 42). All patients underwent best corrected visual acuity (BCVA) measurement, spectral domain-optical coherence tomography (SD-OCT) and fluorescein angiography, while demographic characteristics were also recorded. Specific clinical and morphological characteristics were analyzed and compared between the two groups.

RESULTS

Patients with DME and PDR presented higher central retinal thickness and mixed type of edema, with predominantly cystoid component and large cysts, extending in the foveal, peri- and para-foveal area, compared to patients with DME and NPDR. The presence of non-perfusion areas in patients with DME and PDR led to additional ellipsoid zone and external limiting membrane disruption in a higher percentage, accompanied with worse visual acuity compared to patients with DME and NPDR. Patients with DME and PDR had also higher vitreomacular traction percentage and higher HbA1c levels than those with DME and NPDR.

CONCLUSION

Variations in morphological characteristics of DME on SD-OCT existed between patients with NPDR and those with PDR. These differences may explain the alterations in visual acuity and prognosis.

Macular edema after rhegmatogenous retinal detachment repair: risk factors, OCT analysis, and treatment responses

PURPOSE

To investigate risk factors, imaging characteristics, and treatment responses of cystoid macular edema (CME) after rhegmatogenous retinal detachment (RRD) repair.

METHODS

Consecutive, retrospective case-control series of patients who underwent pars plana vitrectomy (PPV) and/or scleral buckling (SB) for RRD, with at least six months of follow-up. Clinical and surgical parameters of patients with and without CME (nCME), based on spectral-domain optical coherence tomography (OCT), were compared.

RESULTS

Of 99 eyes enrolled, 25 had CME while 74 had nCME. Patients with CME underwent greater numbers of surgeries (P < 0.0001). After adjusting for number of surgeries, macula-off RRD (P = 0.06), proliferative vitreoretinopathy (PVR) (P = 0.09), surgical approach (PPV and/or SB, P = 0.21), and tamponade type (P = 0.10) were not statistically significant, although they all achieved significance on univariate analysis (P = 0.001 or less). Intraoperative retinectomy (P = 0.009) and postoperative pseudophakia or aphakia (P = 0.008) were more frequent in the CME group, even after adjustment. Characteristics of cCME on OCT included diffuse distribution, confluent cysts, and absence of subretinal fluid or intraretinal hyperreflective foci. Macular thickness improved significantly with intravitreal triamcinolone (P = 0.016), but not with anti-vascular endothelial growth factor agents (P = 0.828) or dexamethasone implant (P = 0.125). After adjusting for number of surgeries and macular detachment, final visual acuities remained significantly lower in the CME vs nCME group (P = 0.012).

CONCLUSION

Risk factors of CME include complex retinal detachment repairs requiring multiple surgeries, and pseudophakic or aphakic lens status. Although this cCME was associated with poor therapeutic response, corticosteroids were the most effective studied treatments.

Comparison of intravitreal anti-vascular endothelial growth factor agents and treatment results in Irvine-Gass syndrome

AIM

To compare the efficacy of bevacizumab, ranibizumab, and aflibercept in pseudophakic cystoid macular edema (CME) patients with Irvine-Gass syndrome (IGS).

METHODS

This study is designed as retrospective consecutive case series. Those who developed postoperative pseudophakic CME that refractory to topical treatment and were treated with anti-vascular endothelial growth factor (VEGF) agents included in the study. Optical coherence tomography (OCT) examination including central macular thickness (CMT), total macular volume (TMV), retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) and choroidal thickness (ChT) measurements at the baseline, 1^st, 3^rd and 6^th month controls were performed.

RESULTS

Fifty-nine eyes of 59 patients with CME and other healthy eyes of the patients (Control group) were evaluated. There were 22 eyes of 22 patients in the bevacizumab group (group 1), 19 eyes of 19 patients in the ranibizumab group (group 2), and 18 eyes of 18 patients in the aflibercept group (group 3). There was no difference in terms of age, gender, axial length, IOP, and spherical equivalent values. The baseline subfoveal and mean ChT were higher in the IGS group. The difference between the baseline and sixth month values of subfoveal and mean ChT were compared in the CME groups, thinning was observed in all three groups. GCL was thinner in the patient group at the 6th month of treatment. The resolution time of CME was observed faster in group 1.

CONCLUSION

All three anti-VEGF agents seem to be effective in CME but bevacizumab appears to be slightly more cost-effective than the other two alternatives.

OPTICAL COHERENCE TOMOGRAPHY BIOMARKERS TO DISTINGUISH DIABETIC MACULAR EDEMA FROM PSEUDOPHAKIC CYSTOID MACULAR EDEMA USING MACHINE LEARNING ALGORITHMS

PURPOSE

In diabetic patients presenting with macular edema (ME) shortly after cataract surgery, identifying the underlying pathology can be challenging and influence management. Our aim was to develop a simple clinical classifier able to confirm a diabetic etiology using few spectral domain optical coherence tomography parameters.

METHODS

We analyzed spectral domain optical coherence tomography data of 153 patients with either pseudophakic cystoid ME (n = 57), diabetic ME (n = 86), or "mixed" (n = 10). We used advanced machine learning algorithms to develop a predictive classifier using the smallest number of parameters.

RESULTS

Most differentiating were the existence of hard exudates, hyperreflective foci, subretinal fluid, ME pattern, and the location of cysts within retinal layers. Using only 3 to 6 spectral domain optical coherence tomography parameters, we achieved a sensitivity of 94% to 98%, specificity of 94% to 95%, and an area under the curve of 0.937 to 0.987 (depending on the method) for confirming a diabetic etiology. A simple decision flowchart achieved a sensitivity of 96%, a specificity of 95%, and an area under the curve of 0.937.

CONCLUSION

Confirming a diabetic etiology for edema in cases with uncertainty between diabetic cystoid ME and pseudophakic ME was possible using few spectral domain optical coherence tomography parameters with high accuracy. We propose a clinical decision flowchart for cases with uncertainty, which may support the decision for intravitreal injections rather than topical treatment.

Optical coherence tomographic comparison of naive macular edema due to ischemic and nonischemic retinal vein occlusion

PURPOSE

To examine the macular microstructure in macular edema (ME) due to retinal vein occlusion (RVO) in terms of ischemic or nonischemic type to determine whether and how ischemia affects macular microstructure.

METHODS

This retrospective, nonrandomized study included 75 newly diagnosed RVO cases (group 1: 55 nonischemic RVO cases and group 2: 20 ischemic RVO cases) with evidence of center-involving ME without any treatment. Quantitative measures on spectral-domain optical coherence tomography images were performed. Central subfield thickness (CST) was collected in the central 1 mm from the thickness map. The following items were evaluated in a 3-mm-wide area (perifoveal ETDRS circle) centered on the fovea: disorganization of the retinal inner layers (DRIL), disrupted external limiting membrane (ELM) and ellipsoid zone disruption (EZD). The microstructural changes were measured manually.

RESULTS

Baseline characteristics, such as age, sex, study eye, and RVO risk factors, were similar between the groups (P > 0.05). CST was 554.15 ± 191.45 µm for group 1 and 769.90 ± 290.00 µm for group 2 (P: 0.001). The extent of DRIL was 1864.09 ± 941.70 µm and 2447.25 ± 492.59 µm for groups 1 and 2, respectively (P: 0.010). The disrupted ELM length was 1700 (0-3000) µm for group 1 and 2725 (300-3000) µm for group 2 (P: 0.027). The EZD length was 1453.09 ± 870.38 µm for group 1 and 1846.00 ± 926.54 µm for group 2 (P: 0.093).

CONCLUSIONS

Ischemic RVOs cause greater macular edema and greater disruption in the macular microstructure compared to nonischemic RVOs, especially in terms of DRIL and ELM.

Cystoid macular edema related to cataract surgery and topical prostaglandin analogs: Mechanism, diagnosis, and management

Cystoid macular edema (CME) is a form of macular retina thickening that is characterized by the appearance of cystic fluid-filled intraretinal spaces. It has classically been diagnosed upon investigation after a decrease in visual acuity; however, improvements in imaging technology make it possible to noninvasively detect CME even before a clinically significant decrease in central vision. Risk factors for the development of CME include diabetic retinopathy, retinal vein occlusion, uveitis, and cataract surgery. It has been proposed that eyes with elevated intraocular pressure after cataract surgery, including those treated with prostaglandin analog eye drops, may be at higher risk for the development of CME. We summarize the current knowledge of the molecular mechanisms underlying CME, the potential role of ocular surgery and topical glaucoma medication in increasing the risk of CME, the newly developed imaging methods for diagnosing CME, and the clinical management of CME.

Appearance of cysts and capillary non perfusion areas in diabetic macular edema using two different OCTA devices

The aim of this paper was to distinguish the appearance of cysts and non-perfusion areas (NPAs) in diabetic macular edema (DME) using two different Optical Coherence Tomography Angiography (OCTA) devices. In this study, patients underwent OCTA using the AngioVue XR Avanti Spectral Domain (SD) OCTA and the PLEX Elite 9000 Swept-Source (SS) OCTA. Foveal and extrafoveal regions of interest (ROI), defined as any area with an altered flow signal comparing to the surrounding retina, were selected in superficial and deep capillary plexus (SCP and DCP). ROI reflectivity were classified as hypo-reflective or hyper-reflective. Foveal ROI were analyzed to detect suspended scattering particles in motion (SSPiM). Thirty-seven DME eyes were included. A larger number of ROIs were found in SCP (55 vs 39) and DCP (60 vs 49) using PLEX Elite 9000 vs AngioVue. The majority of ROIs were hypo-reflective with both instruments, while slightly more hyper-reflective ROIs (grey) were detected with the PLEX Elite, more likely to be cysts. The hyporeflective ROIs could be NPAs or cysts with both devices. Moreover, PLEX Elite 9000 identified SSPiM in more foveal ROIs than the AngioVue in the SCP (p = 0.005) and in the DCP (p = 0.027). In conclusion, NPAs and cysts may show variable appearances using different OCTA devices. Hyperreflective ROIs generally correspond to cysts, hyporeflective ROIs can be either cysts or NPAs. The SS-OCTA seems to detect SSPiM more frequently than the SD-OCTA.

Differentiation of Underlying Pathologies of Macular Edema Using Spectral Domain Optical Coherence Tomography (SD-OCT)

Purpose: To describe the morphological characteristics of macular edema (ME) of different origins using spectral domain optical coherence tomography (SD-OCT). Methods: This article summarizes and highlights key morphologic findings, based on published articles, describing the characteristic presentations of ME of different origins using SD-OCT. The following pathologies were included: uveitic macular edema, pseudophakic cystoid macular edema (PCME), diabetic macular edema (DME), macular edema secondary to central or branch retinal vein occlusion (CRVO/BRVO), microcystic macular edema (MME), ME associated with epiretinal membrane (ERM), and retinitis pigmentosa (RP). Conclusions: Macular edema of different origins show characteristic patterns that are often indicative of the underlying cause and pathology. Thus, trained algorithms may in the future be able to automatically differentiate underlying causes and support clinical diagnosis. Knowledge of different appearances support the clinical diagnosis and can lead to improved and more targeted treatment of ME.

BETTER PROGNOSIS FOR EYES WITH PRESERVED FOVEAL DEPRESSION AFTER INTRAVITREAL RANIBIZUMAB INJECTION FOR MACULAR EDEMA SECONDARY TO CENTRAL RETINAL VEIN OCCLUSION

PURPOSE

To determine the prognosis of eyes with central retinal vein occlusion that had a preserved foveal depression at the baseline and were treated by intravitreal ranibizumab injections (IRIs).

METHODS

The authors reviewed the medical records of 23 eyes of 23 consecutive treatment-naive patients who received IRIs to treat the macular edema due to central retinal vein occlusion. Eyes were classified by the pre-IRI presence or absence of a foveal depression. A foveal depression was defined as a central foveal thickness that was <50 μm thinner than the average thickness at 200 μm temporal and nasal to the central fovea. The characteristics of the two groups were compared.

RESULTS

Seven of 23 eyes had a preserved foveal depression before the IRI. The mean number of injections within 12 months after the initial IRI was significantly fewer (P < 0.001) in eyes with foveal depression (1.6 ± 0.5) than in eyes without foveal depression (4.3 ± 1.3). The mean best-corrected visual acuity at 12 months after the initial IRI was significantly better (P = 0.003) in eyes with foveal depression (0.10 ± 0.17 logarithm of the minimum angle of resolution [logMAR] units; 20/25 Snellen units) than in eyes without foveal depression (0.77 ± 0.54 logMAR units; 20/118 Snellen units).

CONCLUSION

These results indicate that the prognosis is better for eyes with a foveal depression before the IRI treatment for a macular edema secondary to central retinal vein occlusion.

Qualitative and quantitative assessment of posterior segment optical coherence tomography images using standard photos: the Liwan Eye Study

BACKGROUND/AIMS

To develop a standardised grading scheme, using standard photos, for spectral-domain ocular coherence tomography (SD-OCT) images of the posterior eye and evaluate the interobserver agreement among trained ophthalmologists in identifying pathological changes.

METHODS

Subjects were recruited from Liwan District, Guangzhou, with SD-OCT data collection from June 2013 to November 2013 as part of 10-year follow-up visits from the Liwan Eye Study. All subjects underwent SD-OCT imaging of the macula with scanning lines analysed by two ophthalmologists to assess for the presence of 12 different posterior segment lesions. Per cent agreement for each lesion between the graders and quantitative measures of dome-shaped macula (DSM) height and choroidal thickness were calculated.

RESULTS

A total of 679 SD-OCT images from 679 subjects were independently evaluated by the two graders. Each of the 12 lesions was successfully graded as present or absent in over 96% of images. For all lesions, per cent agreement between observers was over 90%, ranging from 90.7% for epiretinal membranes and retinal pigment epithelium thickenings to 99.7% for full thickness macular holes and retinal detachments. Quantitative measurements of DSM height and choroidal thickness at three locations of the eye all exhibited intraclass correlation scores between the two graders of greater than 0.9.

CONCLUSION

Our study demonstrates high concordance between graders in characterising posterior segment lesions using SD-OCT images, validating the continued use of this imaging modality in the diagnosis of posterior eye disease.

Mechanisms of macular edema: Beyond the surface

Macular edema consists of intra- or subretinal fluid accumulation in the macular region. It occurs during the course of numerous retinal disorders and can cause severe impairment of central vision. Major causes of macular edema include diabetes, branch and central retinal vein occlusion, choroidal neovascularization, posterior uveitis, postoperative inflammation and central serous chorioretinopathy. The healthy retina is maintained in a relatively dehydrated, transparent state compatible with optimal light transmission by multiple active and passive systems. Fluid accumulation results from an imbalance between processes governing fluid entry and exit, and is driven by Starling equation when inner or outer blood-retinal barriers are disrupted. The multiple and intricate mechanisms involved in retinal hydro-ionic homeostasis, their molecular and cellular basis, and how their deregulation lead to retinal edema, are addressed in this review. Analyzing the distribution of junction proteins and water channels in the human macula, several hypotheses are raised to explain why edema forms specifically in the macular region. "Pure" clinical phenotypes of macular edema, that result presumably from a single causative mechanism, are detailed. Finally, diabetic macular edema is investigated, as a complex multifactorial pathogenic example. This comprehensive review on the current understanding of macular edema and its mechanisms opens perspectives to identify new preventive and therapeutic strategies for this sight-threatening condition.

Automatic detection and recognition of multiple macular lesions in retinal optical coherence tomography images with multi-instance multilabel learning

Detection and recognition of macular lesions in optical coherence tomography (OCT) are very important for retinal diseases diagnosis and treatment. As one kind of retinal disease (e.g., diabetic retinopathy) may contain multiple lesions (e.g., edema, exudates, and microaneurysms) and eye patients may suffer from multiple retinal diseases, multiple lesions often coexist within one retinal image. Therefore, one single-lesion-based detector may not support the diagnosis of clinical eye diseases. To address this issue, we propose a multi-instance multilabel-based lesions recognition (MIML-LR) method for the simultaneous detection and recognition of multiple lesions. The proposed MIML-LR method consists of the following steps: (1) segment the regions of interest (ROIs) for different lesions, (2) compute descriptive instances (features) for each lesion region, (3) construct multilabel detectors, and (4) recognize each ROI with the detectors. The proposed MIML-LR method was tested on 823 clinically labeled OCT images with normal macular and macular with three common lesions: epiretinal membrane, edema, and drusen. For each input OCT image, our MIML-LR method can automatically identify the number of lesions and assign the class labels, achieving the average accuracy of 88.72% for the cases with multiple lesions, which better assists macular disease diagnosis and treatment.

SPECTRAL DOMAIN-OPTICAL COHERENCE TOMOGRAPHY IMAGE CONTRAST AND BACKGROUND COLOR SETTINGS INFLUENCE IDENTIFICATION OF RETINAL STRUCTURES

PURPOSE

To evaluate image contrast and color setting on assessment of retinal structures and morphology in spectral-domain optical coherence tomography.

METHODS

Two hundred and forty-eight Spectralis spectral-domain optical coherence tomography B-scans of 62 patients were analyzed by 4 readers. B-scans were extracted in 4 settings: W + N = white background with black image at normal contrast 9; W + H = white background with black image at maximum contrast 16; B + N = black background with white image at normal contrast 12; B + H = black background with white image at maximum contrast 16. Readers analyzed the images to identify morphologic features. Interreader correlation was calculated. Differences between Fleiss-kappa correlation coefficients were examined using bootstrap method. Any setting with significantly higher correlation coefficient was deemed superior for evaluating specific features.

RESULTS

Correlation coefficients differed among settings. No single setting was superior for all respective spectral-domain optical coherence tomography parameters (P = 0.3773). Some variables showed no differences among settings. Hard exudates and subretinal fluid were best seen with B + H (κ = 0.46, P = 0.0237 and κ = 0.78, P = 0.002). Microaneurysms were best seen with W + N (κ = 0.56, P = 0.025). Vitreomacular interface, enhanced transmission signal, and epiretinal membrane were best identified using all color/contrast settings together (κ = 0.44, P = 0.042, κ = 0.57, P = 0.01, and κ = 0.62, P ≤ 0.0001).

CONCLUSION

Contrast and background affect the evaluation of retinal structures on spectral-domain optical coherence tomography images. No single setting was superior for all features, though certain changes were best seen with specific settings.

Macular atrophy in patients with long-term anti-VEGF treatment for neovascular age-related macular degeneration

PURPOSE

To identify the prevalence and progression of macular atrophy (MA) in neovascular age-related macular degeneration (AMD) patients under long-term anti-vascular endothelial growth factor (VEGF) therapy and to determine risk factors.

METHOD

This retrospective study included patients with neovascular AMD and ≥30 anti-VEGF injections. Macular atrophy (MA) was measured using near infrared and spectral-domain optical coherence tomography (SD-OCT). Yearly growth rate was estimated using square-root transformation to adjust for baseline area and allow for linearization of growth rate. Multiple regression with Akaike information criterion (AIC) as model selection criterion was used to estimate the influence of various parameters on MA area.

RESULTS

Forty-nine eyes (47 patients, mean age 77 ± 14) were included with a mean of 48 ± 13 intravitreal anti-VEGF injections (ranibizumab:37 ± 11, aflibercept:11 ± 6, mean number of injections/year 8 ± 2.1) over a mean treatment period of 6.2 ± 1.3 years (range 4-8.5). Mean best-corrected visual acuity improved from 57 ± 17 letters at baseline (= treatment start) to 60 ± 16 letters at last follow-up. The MA prevalence within and outside the choroidal neovascularization (CNV) border at initial measurement was 45% and increased to 74%. Mean MA area increased from 1.8 ± 2.7 mm² within and 0.5 ± 0.98 mm² outside the CNV boundary to 2.7 ± 3.4 mm² and 1.7 ± 1.8 mm² , respectively. Multivariate regression determined posterior vitreous detachment (PVD) and presence/development of intraretinal cysts (IRCs) as significant factors for total MA size (R² = 0.16, p = 0.02). Macular atrophy (MA) area outside the CNV border was best explained by the presence of reticular pseudodrusen (RPD) and IRC (R² = 0.24, p = 0.02).

CONCLUSION

A majority of patients show MA after long-term anti-VEGF treatment. Reticular pseudodrusen (RPD), IRC and PVD but not number of injections or treatment duration seem to be associated with the MA size.