Evaluation of epiretinal membrane formation after scleral buckling for treating rhegmatogenous retinal detachment: En face optical coherence tomography image-based study

PURPOSE

To assess epiretinal membrane (ERM) formation, severity, and the associated risk factors after scleral buckling using en face optical coherence tomography (OCT) images.

METHODS

Medical records of 61 consecutive patients (66 eyes) with rhegmatogenous retinal detachment who underwent scleral buckling were retrospectively reviewed. Posterior vitreous detachment (PVD) was determined based on B-scan OCT images. En face OCT images were used to visualize the ERM and retinal folds. ERM formation was identified by comparing en face images pre- and post-surgery. The maximum depth of the retinal folds (MDRF) was measured using en face imaging to objectively assess traction strength.

RESULTS

ERM formation occurred in 15 (22.7%) eyes at the final visit; the foveal pit was preserved in all cases. Parafoveal retinal folds were present in 5 (7.6%) eyes, with a mean MDRF of 21.8 ± 12.6 µm. No significant difference was observed in best-corrected visual acuity (logarithm of the minimal angle of resolution) between the ERM formation (-0.019 ± 0.128) and non-ERM formation (-0.001 ± 0.213) groups at the final visit (P = 0.593; Mann-Whitney U test). Multivariate logistic regression analysis revealed that older age and the presence of PVD were significant risk factors for ERM formation (odds ratio 1.07, 95% confidence interval 1.01-1.14, P = 0.032; odds ratio 5.26, 95% confidence interval 1.06-26.10, P = 0.042; respectively).

CONCLUSION

ERM occurred in 22.7% of cases but was mild and did not affect visual acuity. Older age and the presence of PVD are risk factors for ERM formation.

A factor for predicting simultaneous internal limiting membrane peeling during epiretinal membrane removal: swept-source optical coherence tomography-based evaluation of epiretinal membrane adhesion to the retina

PURPOSE

To investigate preoperative factors associated with simultaneous internal limiting membrane (ILM) peeling during epiretinal membrane (ERM) removal.

STUDY DESIGN

Observational cross-sectional study.

METHODS

We retrospectively reviewed 60 eyes with idiopathic ERM that underwent vitrectomy. The gap between the ERM and ILM was visualized using en face optical coherence tomography. The depth and width of the ERM-ILM gap at the initiation site of ERM removal were measured, and the relationship between preoperative factors including these parameters and simultaneous ILM peeling during ERM removal was investigated.

RESULTS

The ILM was simultaneously peeled during ERM removal in 30 eyes, but not in the other 30 eyes. Age was significantly higher (P = 0.017) and the width of the ERM-ILM gap was significantly smaller (P < 0.001) in the simultaneous ILM peeling (+) group than in the simultaneous ILM peeling (-) group. Multivariate logistic regression analysis confirmed the width of the ERM-ILM gap as a significant negative predictor for simultaneous ILM peeling (odds ratio, 0.992; 95% confidence interval, 0.986-0.997; P = 0.003). Receiver operating characteristic curve analysis of the width of the ERM-ILM gap revealed that the optimal cutoff for predicting simultaneous ILM peeling was 187.1 µm.

CONCLUSION

The small width of the ERM-ILM gap at the initiation site of ERM removal was significantly associated with simultaneous ILM peeling, indicating that the adhesion strength between the ERM and ILM at the initial ERM grasping site determines whether simultaneous ILM peeling will occur during ERM removal.

Visualizing and Manipulating Olfactory Cilia Through Viral Delivery Coupled with En Face Imaging of Intact OE

Olfactory cilia are the obligate transducers of the odorant signal, and thus their study has been a focus of investigation in the olfactory field. Various methodologies have been established to visualize the cilia of olfactory sensory neurons; however, these approaches are limited to static imaging and often lack the ability to resolve individual cilia projecting from solitary neurons in the postnatal mouse. Here we detail a procedure of the visualization of olfactory cilia by ectopic expression of fluorescently tagged proteins. The procedure can be used for the observation and manipulation of the olfactory cilia and ciliary proteins in both static and dynamic conditions.

Regression patterns of central serous chorioretinopathy using en face optical coherence tomography

PURPOSE

To study the regression patterns of subretinal fluid (SRF) in central serous chorioretinopathy (CSCR) on sequential en face optical coherence tomography (OCT) and its relationship to leak locations.

METHODS

Retrospective study on patients with acute CSCR. Inclusion criteria were (i) availability of data, sequential OCT and OCT angiography (B scan and en face OCT) every 2 weeks until resolution of SRF or 6 months, whichever is earlier; (ii) single active leak. Exclusion criteria were (i) presence of macular neovascularization or atypical CSCR, (ii) diffuse pigment epitheliopathy, (iii) multiple leaks. Serial en face OCT scans were evaluated and the area of SRF was measured using ImageJ software. Correlation coefficient was calculated for the regression rate of SRF area and central retinal thickness (CRT) over the first month of follow-up and the time of complete SRF resolution.

RESULTS

Out of the 25 eyes, 20 eyes demonstrated a centripetal regression, and 5 eyes demonstrated a centrifugal regression. In eyes with a leakage point <1000μ from the fovea, 86% resolved in a centripetal fashion, and in eyes with leak site ≥1000μ away from fovea, 70% eyes resolved centripetally. There was a correlation (r=-0.47, p=0.018) of the rate regression of SRF area during the first month and timing of resolution. In contrast, this correlation was absent (r=-0.16, p=0.44) for CRT regression.

CONCLUSION

Our en face-based analysis of sequential OCTs of regressing CSCR demonstrated a tendency for the subfoveal SRF to resolve towards the end or a centripetal pattern of regression. Prediction of resolution of SRF at 1 month is better with en face area of SRF in comparison to CRT.

Variation of vortex veins at the horizontal watershed in normal eyes

PURPOSE

To assess the vascular pattern of choroidal vortex veins at the horizontal watershed zone in normal eyes using optical coherence tomography (OCT).

METHODS

We retrospectively studied 207 normal eyes of 207 patients whose fellow eyes were diagnosed with unilateral retinal diseases without choroidal involvement. Venous anastomosis between the superior and inferior vortex veins and deviation of the horizontal watershed zone were evaluated using 12 × 12-mm en face OCT images. Central choroidal thickness (CCT) was measured on B-mode OCT images.

RESULTS

Vortex vein anastomosis was observed in 92 eyes (44.4%) at the horizontal watershed zone. Superior or inferior deviation of the horizontal watershed was ascertained in 69 eyes (33.3%). The frequency of the anastomosis and deviation did not differ significantly between age groups (P = 0.56 and 0.96, respectively). Mean CCT of all eyes was 221 ± 80 μm. CCT was significantly greater in eyes with anastomosis than in those without (233 ± 73 μm vs 210 ± 83 μm, P < 0.05). However, CCT did not differ significantly between eyes with and without deviation of the horizontal watershed zone (223 ± 74 μm vs 219 ± 82 μm).

CONCLUSIONS

Venous anastomosis at the horizontal watershed zone as well as superior or inferior deviation of the zone were frequently observed in normal eyes. CCT was greater in eyes with than in those without anastomosis, suggesting subclinical vortex vein congestion.

Non-invasive imaging of a choroidal macrovessel

Purpose

To describe novel anatomic findings of an apparent choroidal macrovessel, originally misdiagnosed as a choroidal tumor, using non-invasive imaging tools.

Observations

Initial ophthalmic examination revealed an elevated hypopigmented choroidal mass in the macular area, with a serpentine track extending temporally to the equator. Enhanced depth imaging optical coherence tomography (EDI-OCT) revealed an optically hollow lesion just outside the choroid-scleral junction (CSJ), indenting the retina and compressing the choroid from the scleral side. Optical coherence tomography angiography (OCTA) at the choroidal level showed relative low flow within the lesion. En face OCT at the level of the choroid demonstrated similar reflectivity to the physiological adjacent choroidal vessels.

Conclusion and importance

Non-invasive imaging can be used to demonstrate the presence and anatomy of a choroidal macrovessel. OCTA is presented as a useful diagnostic imaging test that can distinguish this lesion from alternative diagnoses without the use of dye injection. In addition to the previously published reports of such vessels in the choroid, we suggest a possible anatomic variant infra-choroidal location of a macrovessel and hypothesize its origin.

Running pattern of choroidal vessel in en face OCT images determined by machine learning-based quantitative method

PURPOSE

To evaluate the new method to quantitate the running pattern of the vessels in Haller's layer in en face optical coherence tomographic (OCT) images using the new algorithm.

METHODS

A retrospective and cross-sectional study. The en face image of top 25% slab of Haller's layer was analyzed. The vascular area in these images was calculated after binarization. Then, the vessels were thinned, and the total length of the vessels and the mean vessel diameter were calculated. Based on the angle of vessel running, "natural oblique vessel" was defined. The ratio of the natural oblique vessel to the whole vessels was defined as the "symmetry index". To examine the reproducibility of the software, the images obtained on two different examination dates of the same subject (25 eyes of 25 healthy subjects) were analyzed. Also, to compare the symmetry index and subjective evaluations, 180 eyes and 180 healthy subjects were analyzed. The subjective evaluations classified the images into 3 groups, the Symmetrical, Semi-symmetrical, and Asymmetrical types. Symmetry index was compared in each group.

RESULTS

The inter-measurement correlation coefficient (ICC) of the vessel area, vessel length, and vessel diameter were 0.955, 0.934, and 0.954, respectively. The ICC of the symmetry index was 0.926. The symmetry index of the Symmetrical type was 60.4 ± 7.2%, that of the Semi-symmetry type was 56.2 ± 4.6%, and that of the Asymmetry type was 52.6 ± 5.2%.

CONCLUSIONS

The present algorithm can analyze vessels in Haller's layer of the en face images of choroid in an objective manner with good repeatability.

Combined in-depth, 3D, en face imaging of the optic disc, optic disc pits and optic disc pit maculopathy using swept-source megahertz OCT at 1050 nm

Purpose

To demonstrate papillary imaging of eyes with optic disc pits (ODP) or optic disc pit associated maculopathy (ODP-M) with ultrahigh-speed swept-source optical coherence tomography (SS-OCT) at 1.68 million A-scans/s. To generate 3D-renderings of the papillary area with 3D volume-reconstructions of the ODP and highly resolved en face images from a single densely-sampled megahertz-OCT (MHz-OCT) dataset for investigation of ODP-characteristics.

Methods

A 1.68 MHz-prototype SS-MHz-OCT system at 1050 nm based on a Fourier-domain mode-locked laser was employed to acquire high-definition, 3D datasets with a dense sampling of 1600 × 1600 A-scans over a 45° field of view. Six eyes with ODPs, and two further eyes with glaucomatous alteration or without ocular pathology are presented. 3D-rendering of the deep papillary structures, virtual 3D-reconstructions of the ODPs and depth resolved isotropic en face images were generated using semiautomatic segmentation.

Results

3D-rendering and en face imaging of the optic disc, ODPs and ODP associated pathologies showed a broad spectrum regarding ODP characteristics. Between individuals the shape of the ODP and the appending pathologies varied considerably. MHz-OCT en face imaging generates distinct top-view images of ODPs and ODP-M. MHz-OCT generates high resolution images of retinal pathologies associated with ODP-M and allows visualizing ODPs with depths of up to 2.7 mm.

Conclusions

Different patterns of ODPs can be visualized in patients for the first time using 3D-reconstructions and co-registered high-definition en face images extracted from a single densely sampled 1050 nm megahertz-OCT (MHz-OCT) dataset. As the immediate vicinity to the SAS and the site of intrapapillary proliferation is located at the bottom of the ODP it is crucial to image the complete structure and the whole depth of ODPs. Especially in very deep pits, where non-swept-source OCT fails to reach the bottom, conventional swept-source devices and the MHz-OCT alike are feasible and beneficial methods to examine deep details of optic disc pathologies, while the MHz-OCT bears the advantage of an essentially swifter imaging process.

Electronic supplementary material

The online version of this article (10.1007/s00417-017-3857-9) contains supplementary material, which is available to authorized users.