Early retinal flow changes after vitreoretinal surgery in idiopathic epiretinal membrane using swept source optical coherence tomography angiography

Microvascular Changes after Epiretinal Membrane Vitrectomy with Intraoperative Intravitreal Dexamethasone Implant: An OCT Angiography Analysis

BACKGROUND

We aimed to explore microvascular changes evaluated with optical coherence tomography angiography (OCTA) in patients undergoing epiretinal membrane (ERM) pars-plana vitrectomy (PPV) combined with intravitreal Ozurdex implantation, compared with standard PPV. (2) Methods: Prospective interventional analysis on 25 eyes undergoing PPV + Ozurdex (Group A) and 25 eyes undergoing PPV alone. Best corrected visual acuity (BCVA) and OCTA parameters, such as vessel density (VD) of the superficial and deep capillary plexi (SCP and DCP) in the whole 6.4 mm × 6.4 mm and fovea area, were evaluated preoperatively and 3 months after surgery. (3) Results: Postoperative BCVA significantly improved in both groups. No cases of post-operative cystoid macular edema (CME) were reported in Group A vs. two eyes in Group B. In Group A we found a statistically significant increase of SCP's VD in either the whole image (from 42.1 ± 4.1 to 45.6 ± 4.3%, p = 0.01) and the fovea image (from 38.5 ± 7.5 to 41.7 ± 4.2%, p = 0.03). In Group B, we reported no significant variations in the SCP's VDs. In the DCP, VD significantly increased only in the whole image in Group A. Stage 4 ERMs showed the greatest improvement in VD, especially in Group A. (4) Conclusions: Intraoperative Ozurdex prompted a significant BCVA recovery and limited the occurrence of postoperative CME compared to the standard procedure. Moreover, Ozurdex implant is associated with a better restoration of microvascular structure in SCP and DCP.

Application of ImageJ in Optical Coherence Tomography Angiography (OCT-A): A Literature Review

Background

This study aimed to review the literature on the application of ImageJ in optical coherence tomography angiography (OCT-A) images.

Methods

A general search was performed in PubMed, Google Scholar, and Scopus databases. The authors evaluated each of the selected articles in order to assess the implementation of ImageJ in OCT-A images.

Results

ImageJ can aid in reducing artifacts, enhancing image quality to increase the accuracy of the process and analysis, processing and analyzing images, generating comparable parameters such as the parameters that assess perfusion of the layers (vessel density (VD), skeletonized density (SD), and vessel length density (VLD)) and the parameters that evaluate the structure of the layers (fractal dimension (FD), vessel density index (VDI), and lacunarity (LAC)), and the foveal avascular zone (FAZ) that are used widely in the retinal and choroidal studies), and establishing diagnostic criteria. It can help to save time when the dataset is huge with numerous plugins and options for image processing and analysis with reliable results. Diverse studies implemented distinct binarization and thresholding techniques, resulting in disparate outcomes and incomparable parameters. Uniformity in methodology is required to acquire comparable data from studies employing diverse processing and analysis techniques that yield varied outcomes.

Conclusion

Researchers and professionals might benefit from using ImageJ because of how quickly and correctly it processes and analyzes images. It is highly adaptable and potent software, allowing users to evaluate images in a variety of ways. There exists a diverse range of methodologies for analyzing OCTA images through the utilization of ImageJ. However, it is imperative to establish a standardized strategy to ensure the reliability and consistency of the method for research purposes.

Correlation between retinal sensitivity and retinal vascular perfusion after idiopathic epiretinal membrane peeling

BACKGROUND

To evaluate the correlations between anatomical and functional changes after idiopathic epiretinal membrane (iERM) surgery.

METHODS

In this prospective, observational, single-center study, consecutive patients who underwent iERM peeling were enrolled. Reported data were pre- and postoperative best-corrected visual acuity (BCVA), retinal sensitivity (RS) and fixation stability values on microperimetry, structural macular features on SD-OCT and OCTA. RS of foveal and parafoveal area was analysed and two sub-groups were identified whether RS improved or remained unchanged/worsened after surgery; consequently, vascular perfusion density (VPD) of the same area was studied.

RESULTS

Twenty-nine eyes of 29 patients were examined. The post-operative improvement in terms of BCVA, RS and fixation within the central 4 degrees was significant (p < 0.001, p < 0.001, p = 0.001), as well as the foveal thickness and macular volume change/reduction (p < 0.001). The pre-operative superficial VPD, choriocapillaris VPD and capillary free zone (CFZ) area were significantly reduced compared to the fellow healthy eye (p = 0.001, p = 0.02, p < 0.001). Choriocapillaris VPD showed a statistically significant increase after surgery (p < 0.02). Superficial, deep and choriocapillaris VPD of the improved RS group showed a significant increase both in foveal (p = 0.03, p = 0.03, p = 0.01) and parafoveal areas (p = 0.01, p = 0.03, p = 0.001).

CONCLUSIONS

We reported a higher VPD in the retinal area that experienced a retinal sensitivity improvement 6 months after ERM surgery. This result objectifies the tight bond between visual function and retinal perfusion in ERM patients.

[Effects of internal limiting membrane peeling in epiretinal membrane surgery on OCT-angiography]

PURPOSE

To assess macular microvascular parameters using OCT-angiography (OCT-A) in idiopathic epiretinal membrane surgery with or without internal limiting membrane peeling.

MATERIALS AND METHODS

We retrospectively studied 17 eyes of 17 patients who underwent vitrectomy surgery for idiopathic epiretinal membrane with (n=10) or without (n=7) internal limiting membrane peeling. Patients operated on between July 2020 and June 2022 at the Colmar Hospital (France) by a single surgeon were evaluated before and 1 month after surgery, using OCT-A (Spectralis OCT-A module, Heidelberg Engineering®, Germany). The parameters studied were the area, perimeter and acircularity index of the foveal avascular zone (FAZ), the foveolar (FVD) and parafoveolar (PRVD) perfusion density and the macular vessel density ratio (MVR) in the superficial vascular complex (SVC) and the deep vascular complex (DVC). These parameters were measured using ImageJ software (National Institutes of Health, Bethesda, Maryland, USA).

RESULTS

We found no statistically significant difference between the two groups postoperatively in either area, perimeter, or acircularity index of the FAZ, FVD, PRVD, or MVR in either the SVC or DVC.

CONCLUSION

Our results with regard to macular microvasculature demonstrate no difference related to peeling of the internal limiting membrane and thus do not argue against this practice during epiretinal membrane surgery.

Epiretinal membrane related vascular changes in diabetic eyes evaluated with optical coherence tomography angiography

AIM

To evaluate the retinochoroidal microvascular circulation and anatomical structure of diabetic and non-diabetic patients with epiretinal membrane (ERM) with the help of optical coherence tomography angiography (OCT-A) and compare them with healthy control subjects.

METHODS

In this prospective, cross-sectional study, a total of 165 eyes were evaluated, including 50 eyes of patients with diabetic ERM, 54 eyes of idiopathic ERM (iERM) patients, and 61 eyes of healthy controls. Macula and disc angiography was performed by OCT-A. Macular vessel density (VD) ratio was evaluated by dividing the VD of the foveal region by the VD of the parafoveal region. Statistical calculations were evaluated at the 95% confidence interval.

RESULTS

Macula superficial VD values of ERM cases were lower than that in the control group, while foveal VD was higher in ERM cases. Macula deep VD values of ERM cases were lower in all quadrants, except the fovea. The width of the foveal avascular zone (FAZ) area was significantly lower in the ERM groups, and the FAZ width was lowest in iERM group. Macula superficial VD ratio was significantly higher in the ERM groups, but there was no significant difference between ERM groups. Macula deep VD ratio was significantly higher in the iERM group than in the control group.

CONCLUSION

Diabetic and idiopathic ERMs differ in their mechanism of formation and clinical presentation, as well as their effect on retinal vascular structures. If the relationship of increase of retinal thickness with vascular integrity can be demonstrated with OCT-A, then, OCT-A can be used as a guide for ERM prognosis.

[Clinical and pathophysiological contribution of OCT-angiography to epiretinal membranes]

Epiretinal membranes may lead to centripetal contraction forces on the retina and its vessels. OCT-Angiography (OCT-A) is a recent tool which permits a non-invasive understanding of these vascular changes. This review focuses on the OCT-A findings in idiopathic epiretinal membranes, before and after surgery, and the role of internal limiting membrane peeling. It appears that contraction of the epiretinal membrane is associated with both a reduction in the area and perimeter of the foveal avascular zone and alterations in the superficial and deep capillary plexuses. These changes mainly reflect a vascular shift from the perifoveal to the foveal region, increasing with retinal deformation, but also probable dynamic changes in vascular flow. Membrane peeling allows at least partial improvement of these microvascular parameters. Nevertheless, some limitations of OCT-A, such as segmentation errors on a retina with highly modified architecture, can lead to a selection bias in the studies and should call for caution in the interpretation of the results. Finally, internal limiting membrane peeling contributes to changes in the retinal architecture after surgery, in particular by causing a centripetal movement of the macular capillaries and a displacement of the fovea toward the optic nerve head. This role should be clarified in future studies.

Associations between macular retinal vasculature and severity of idiopathic epiretinal membrane

BACKGROUND

To demonstrate the associations between the morphology of macular retinal vasculature and disease severity of idiopathic epiretinal membrane (ERM).

METHODS

Macular structures were assessed using optical coherence tomography (OCT), and were classified as "with pseudohole" or "without pseudohole". The 3 × 3 mm macular OCT angiography images were analyzed using the Fiji software to obtain the vessel density, skeleton density, average vessel diameter, vessel tortuosity, fractal dimension, and foveal avascular zone (FAZ)-related parameters. The correlations between these parameters and ERM grading as well as visual acuity were analyzed.

RESULTS

For ERM with or without a pseudohole, increased average vessel diameter, decreased skeleton density, and decreased vessel tortuosity were all associated with inner retinal folding and thickened inner nuclear layer, indicating more severe ERM. In 191 eyes without a pseudohole, the average vessel diameter increased, fractal dimension decreased and vessel tortuosity decreased with increasing ERM severity. The FAZ was not associated with ERM severity. Decreased skeleton density (r = -0.37), vessel tortuosity (r = -0.35), and increased average vessel diameter (r = 0.42) were correlated with worse visual acuity (All P < 0.001). In 58 eyes with pseudoholes, a larger FAZ was associated with a smaller average vessel diameter (r = -0.43, P = 0.015), higher skeleton density (r = 0.49, P < 0.001), and vessel tortuosity (r = 0.32, P = 0.015). However, none of the retinal vasculature parameters correlated with visual acuity and central foveal thickness.

CONCLUSION

Increased average vessel diameter, decreased skeleton density, decreased fractal dimension and decreased vessel tortuosity were good indicators of ERM severity and associated visual impairment.

Image processing and quantification analysis for optical coherence tomography angiography in epiretinal membrane

BACKGROUND

To explore image processing methods for optical coherence tomography angiography (OCTA) of the epiretinal membrane (ERM), and to evaluate the impact of ERM on vision by analyzing the retinal vasculature.

METHODS

Thirty eyes of 30 patients with idiopathic ERM who underwent OCTA were retrospectively evaluated. Image processing of OCTA, including the Mexican hat filter (MHF) and exclusion of the foveal avascular zone (FAZ), was attempted using Fiji. OCTA parameters, including vessel density (VD), fractal dimension (FD), and vessel tortuosity (VT), were measured for large vessels only, capillaries only, and the whole vasculature. Pearson correlation analysis was used to evaluate the correlations between best-corrected visual acuity (BCVA) and OCTA parameters.

RESULTS

The correlations between BCVA and retinal vasculature were much increased when the capillaries only instead of the whole vasculature was used for analysis. Both higher VD and FD of capillaries were correlated with better BCVA, and MHF largely increased their correlations (P < 0.0001 for both). In contrast, both higher VD and FD of the large vessels were associated with poorer BCVA (P = 0.042 and 0.049, respectively). A higher VT of capillaries was correlated with better BCVA, and both MHF and exclusion of the FAZ were necessary to reveal their correlations (P = 0.028) CONCLUSIONS: Separation of large vessels and capillaries was necessary to reveal the correlation between retinal vasculature and BCVA in ERM. MHF was necessary to elucidate all microvascular parameters of capillaries, and exclusion of the FAZ was mandatory for evaluation of VT.

Retinal Vascular Tortuosity Index Change after Idiopathic Epiretinal Membrane Surgery: Does Internal Limiting Membrane Peeling Affect Retinal Vascular Tortuosity?

BACKGROUND

Idiopathic epiretinal membrane (iERM) surgery is one of the most commonly performed vitreoretinal surgeries, and the issue of internal limiting membrane (ILM) peeling in ERM surgery is still controversial. The aims of this study are to evaluate the changes in retinal vascular tortuosity index (RVTI) after pars plana vitrectomy for the iERM using optical coherence tomography angiography (OCTA) and to assess whether ILM peeling has an additional effect on RVTI reduction.

METHODS

This study included25 eyes of 25 iERM patients who underwent ERM surgery. The ERM was removed without ILM peeling in 10 eyes (40.0%), and the ILM was peeled in addition to the ERM in 15 eyes (60.0%). The existence of the ILM after ERM peeling was checked with second staining in all eyes. Best corrected visual acuity (BCVA) and 6 × 6 mm en-face OCTA images were recorded before surgery and at the first month postoperatively. A skeleton model of the retinal vascular structure was created following Otsu binarization of en-face OCTA images using ImageJ software (1.52U). RVTI was calculated as the ratio of each vessel length to its Euclidean distance on the skeleton model using the Analyze Skeleton plug-in.

RESULTS

The mean RVTI declined from 1.220 ± 0.017 to 1.201 ± 0.020 (p = 0.036) in eyes with ILM peeling and from 1.230 ± 0.038 to 1.195 ± 0.024 in eyes without ILM peeling (p = 0.037). There was no difference between the groups in terms of postoperative RVTI (p = 0.494). A statistically significant correlation was found between postoperative RVTI and postoperative BCVA (rho = 0.408, p = 0.043).

CONCLUSIONS

The RVTI is an indirect indicator of the traction created by the iERM on retinal microvascular structures, and it was effectively reduced after iERM surgery. The postoperative RVTIs were similar in cases who underwent iERM surgery with or without ILM peeling. Therefore, ILM peeling may not have an additive effect on the loosening of microvascular traction and thus may be reserved for recurrent ERM surgeries.

Effect of Internal Limiting Membrane Peeling or Not on Blood Flow Signal in Macular Area of Diabetic Patients with Preretinal Membrane

PURPOSE

To study the effect of intraoperative internal limiting membrane (ILM) peeling on the macular vascular structure in patients with diabetic epiretinal membrane (ERM).

METHODS

Patients with diabetic ERM were divided into an ERM + ILM peeling group (18 eyes) and an ERM peeling group (19 eyes), all of whom underwent standard vitrectomy and were followed up until 6 months postoperatively. Best-corrected visual acuity (BCVA), Central macular thickness (CMT), Vessel density (VD) and vessel length density (VLD) of the superficial as well as deep retinal capillary plexus were compared between the two groups.

RESULTS

There was no significant difference in BCVA (p = .188, .410, .901, .916) and CMT (p = .164, .128, .110, .105) between the two groups at the week 1, month 1, month 3 and month 6 after operation. In the superficial capillary plexus (SCP), the change in VD (p = .106) and VLD (p = .438) was not affected by ILM peeling, and there was no significant difference in VD (p = .154, .063, .100, .162) and VLD (p = .386, .263, .431, .391) between the two groups during the four follow-up after operation. For the deep capillary plexus (DCP), there was an effect of ILM peeling on the changes in VD (p = .024) and VLD (p = .012), ILM peeling delayed the recovery time of the VD and VLD; The VD (p = .026, .000, .003) and VLD (p = .005, .000, .000) of ERM + ILM peeling group were lower than those of ERM peeling group from the month 1 to the month 6 after operation.

CONCLUSION

Intraoperative peeling of the ILM in patients with diabetic ERM delayed the improvement of blood flow signal in the DCP but did not affect the recovery of postoperative BCVA and CMT.

Postoperative Changes in Vessel Density according to Macular Hole and Macular Pseudohole Subtypes

Purpose: To determine the postoperative changes in vessel density according to macular hole and macular pseudohole (MPH) subtypes and to investigate the differences in the mechanisms underlying their development. We also investigated whether changes in vessel density are correlated with changes in the multifocal electroretinogram (mfERG) and best corrected visual acuity (BCVA).Methods: We reviewed the medical records of patients with MPH or a macular hole who underwent pars plana vitrectomy. We included 15 eyes of 15 patients with a full thickness macular hole (FTMH), nine eyes of nine patients with a tractional lamellar macular hole (LMH), eight eyes of eight patients with a degenerative LMH, and nine eyes of eight patients with a MPH. The BCVA, foveal avascular zone (FAZ), foveal and parafoveal vessel density, and mfERG ring 1 and ring 2 P1 amplitudes were analyzed before and 1 and 6 months after surgery.Results: One month postoperatively, the foveal vessel density of patients with a MPH or tractional LMH increased (p = 0.011, p = 0.008). The parafoveal vessel density of patients with a MPH, tractional LMH, and FTMH increased (p = 0.007, p = 0.038, p = 0.031). There was no significant increase in foveal or parafoveal vessel density in patients with a degenerative LMH (p = 0.201, p = 0.171). There was a significant correlation between the change in parafoveal vessel density and that in BCVA 6 months postoperatively in patients with a FTMH (r = -0.543, p = 0.037).Conclusions: By assessing changes in vessel density after vitrectomy, it is possible to estimate the effect of traction according to the type of macular hole. There was a significant correlation between parafoveal vessel density and BCVA in patients with a FTMH. Restoration of the retinal structure and vessel density might improve visual acuity.

Assessment of macular microvasculature features before and after vitrectomy in the idiopathic macular epiretinal membrane using a grading system: An optical coherence tomography angiography study

PURPOSE

To evaluate pre- and postoperative microvasculature features in eyes with different idiopathic macular epiretinal membrane (iERM) classifications using optical coherence tomography angiography (OCTA).

METHODS

In this retrospective study, 100 eyes with iERM were enrolled; 62 eyes underwent pars plana vitrectomy (PPV). All iERM eyes were evaluated and graded using optical coherence tomography (OCT). According to the thickness of the fovea relative to the surrounding macula from OCT radial line scans, we classified iERM into three grades. Optical coherence tomography angiography (OCTA) was used to measure the foveal avascular zone (FAZ)-related parameters and the superficial and deep capillary plexus layers using 3 × 3 mm scans. Measurements were taken at baseline and 3 months postoperatively. Best corrected visual acuity (BCVA), vessel density (VD), FAZ area, FAZ perimeter (PERIM), acircularity index (AI), and foveal vessel density (FD) were evaluated.

RESULTS

Idiopathic macular epiretinal membrane (iERM) eyes with a higher grade had a lower FAZ area and perimeter (p < 0.0001), higher foveal vessel density (FVD) both in the superficial capillary plexus (SCP) (p < 0.0001) and in the deep capillary plexus (DCP) (p < 0.05), and a lower parafoveal vessel density (PRVD) in the DCP (p < 0.0001). The macular vessel density ratio (MVR = FVD/PRVD) increased with an increase in grade both in the SCP and in the DCP (p < 0.0001). For grade 1 iERM eyes, only PRVD in the DCP significantly changed before versus after the operation (p < 0.05). For grade 2 iERM eyes, the FAZ area and perimeter became larger after the operation (p < 0.05). The MVR of grade 2 iERM eyes decreased postoperatively both in the SCP (p < 0.05) and in the DCP (p < 0.001). For grade 1 and grade 2 iERM eyes, preoperative LogMAR BCVA was negatively correlated with the FAZ area (p < 0.01) and perimeter (p < 0.01), and was positively correlated with the MVR in the SCP (p < 0.05). Postoperative LogMAR BCVA was positively correlated with the FVD in the DCP (p < 0.05).

CONCLUSIONS

Idiopathic macular epiretinal membrane (iERM) eyes of different grades have significant differences in microvasculature features. According to OCTA, eyes with higher grades have more serious microvascular changes. Grading plays a part in predicting postoperative microvascular characteristics, and grade 1 iERM eyes have a better visual outcome compared with grade 2 iERM eyes.

Early Vascular and Functional Changes after Vitreoretinal Surgery: A Comparison between the Macular Hole and Epiretinal Membrane

(1) Background: The aim of this observational comparative study was to investigate early retinal vascular and functional changes in patients undergoing vitreoretinal surgery for idiopathic epiretinal membrane (iERM) or macular hole (MH) using a widefield swept-source optical coherence tomography angiography (WSS-OCTA). (2) Methods: Forty one diseased eyes were enrolled in the study. Twenty three eyes with iERM diagnosis (ERM group) underwent 25-gauge vitrectomy with inner limiting membrane (ILM) and MER peeling, while eighteen eyes with MH (MH group) underwent 25-gauge vitrectomy with inverted flap technique. Functional and anatomical/perfusion parameters were evaluated pre- and postoperatively in all eyes by means of WSS-OCTA system, microperimetry (MP3), best corrected visual acuity assessment, central macular thickness (CMT) and MH diameter calculation. For each eye, 12 × 12 mm OCTA volume scans were acquired by a retinal specialist and a semi-automated algorithm was used for a quantitative vessel analysis of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC). In detail, perfusion density (PD) of the SCP, DCP and CC was evaluated in four circles (one central in the macular area of 5 mm diameter; three midperiphery circles (temporal, superior and inferior) of 3 mm). In addition, the vessel length density (VLD) of the SCP and DCP for the same circles was quantified. (3) Results: In the MH group, PD of the SCP significantly increased in the macular area (p = 0.018) and in the superior ring (p = 0.016); PD of the DCP significantly increased in the macular area (p = 0.015) and in the superior and inferior ring (p = 0.016) 3 months after surgery. In the ERM group, PD of the SCP and DCP significantly increased in the macular area and superior ring, respectively (p = 0.001; p = 0.032), 3 months after surgery. During follow-up there was a significant improvement in terms of functional (Best corrected visual acuity, p = 0.007 and p = 0.029; microperimetry ((MP3) 10°, p = 0.003 and p = 0.004; MP3 2°, p = 0.028 and p = 0.003 in MH group and ERM group respectively) and anatomical parameters (CMT, p = 0.049 in ERM group; hole complete closure in MH group). (4) Conclusions: After vitreoretinal surgery, early retinal vascular and functional changes can be promptly observed and quantified to monitor and potentially predict surgery outcomes. Widefield OCTA devices allow for a detailed microvasculature analysis of retina and choriocapillaris in the macular area and in the periphery, showing a different behaviour of retinal sectors in two distinct vitreoretinal disorders.

Epiretinal membrane: A review

The prevalence of epiretinal membrane (ERM) is 7% to 11.8%, with increasing age being the most important risk factor. Although most ERM is idiopathic, common secondary causes include cataract surgery, retinal vascular disease, uveitis and retinal tears. The myofibroblastic pre-retinal cells are thought to transdifferentiate from glial and retinal pigment epithelial cells that reach the retinal surface via defects in the internal limiting membrane (ILM) or from the vitreous cavity. Grading schemes have evolved from clinical signs to ocular coherence tomography (OCT) based classification with associated features such as the cotton ball sign. Features predictive of better prognosis include absence of ectopic inner foveal layers, cystoid macular oedema, acquired vitelliform lesions and ellipsoid and cone outer segment termination defects. OCT-angiography shows reduced size of the foveal avascular zone. Vitrectomy with membrane peeling remains the mainstay of treatment for symptomatic ERMs. Additional ILM peeling reduces recurrence but is associated with anatomical changes including inner retinal dimpling.

The Role of OCT Angiography in the Assessment of Epiretinal Macular Membrane

Background

The aim of this observational study is to assess pre- and postoperative retinochoroidal vascular changes in patients undergoing epiretinal macular membrane (ERM) surgery by using optical coherence tomography angiography (OCTA).

Materials and Methods

23 eyes affected by ERM and those which underwent phacovitrectomy associated with ERM peeling were enrolled. They were evaluated using structural OCT and OCTA before surgery and at 1, 3, and 6 months postoperatively.

Results

We found a statistically significant (p < 0.05) increase in the superficial capillary plexus vessel density (VD) from baseline to the 6-month follow-up. We observed a large increase in both the perfusion density (PD) and the VD of the deep capillary plexus between baseline and the 6-month follow-up (p < 0.001). A significant decrease in the VD and PD of the choriocapillaris (CC) from baseline to the 1^st month and a significant increase in CC perfusion density at the 6-month follow-up compared to the preoperative value were revealed. The FAZ area and perimeter after surgery significantly increased during the follow-up (p < 0.001) at baseline retinal and choroidal plexi with a lower PD or VD correlated with worse visual acuity (p < 0.05 for all plexi). At baseline and at the 1-month follow-up, a significant correlation was found with the FAZ area and the FAZ perimeter: a smaller FAZ area or a smaller FAZ perimeter was correlated to a lower visual acuity. Before surgery, negative correlations (p < 0.05) were found between the Govetto ERM stages and perfusion density of the SCP and the DCP and between the Govetto stages and vessel density of the DCP.

Conclusions

In our study, OCTA detected vascular alterations induced by the presence of the ERM, allowing several correlations with functional data. In these patients, OCTA may be useful to add new potential surgical prognostic factors.

Influences of Central Bouquet Alterations on the Visual Outcome in Eyes Receiving Epiretinal Membrane Surgery

Background: Previous studies have shown that epiretinal membranes (ERMs) may be associated with abnormal outer retinal anatomy. However, long-term morphological and functional results of pars plana vitrectomy (PPV) with ERM and internal limiting membrane (ILM) peeling in eyes with central bouquet (CB) alterations have not yet been investigated. Methods: In a retrospective, consecutive study all patients underwent best corrected visual acuity (BCVA) testing and spectral domain optical coherence tomography (SD-OCT) before and after a mean of 20 months (range 3–70 months) postoperatively. CB abnormalities and ERMs were classified according to Govetto’s staging systems. Results: Of the 67 eyes, 22 (34%) showed CB abnormalities at baseline. The mean BCVA increased from 0.42 at baseline to 0.20 LogMAR at final follow-up (p < 0.001). Neither ERM stage (p = 0.06) nor CB stage (p = 0.939) at baseline were significant predictors of vision improvement following surgery. Conclusions: Our results show that baseline BCVA, but not classification of CB changes and ERM at baseline, seems to be a useful predictor for functional outcomes following PPV with ERM and ILM peeling in the long-term.

OCT-A in the Management of Vitreoretinal Diseases and Surgery

ABSTRACT

Optical coherence tomography angiography is a relatively new noninvasive technique that is changing our approach in the management of several retinal diseases such as neovascular age-related macular degeneration, occlusive retinal diseases, or diabetic retinopathy, but it could also be useful in nonprimary vascular retinal pathologies such as vitreoretinal interface surgical disorders.In idiopathic vitreoretinal interface disorders and surgical retinal diseases, the study of vascular involvement, not commonly assessed by invasive methods, could be useful to reveal specific vascular abnormalities. Such information may be useful for a more detailed phenotyping of each clinical picture before and after surgical treatment, providing potential new prognostic biomarkers.The review discusses the current and potential utility of optical coherence tomography angiography to study vitreoretinal pathologies of surgical interest.

Epiretinal Membrane Surgery: Structural Retinal Changes Correlate with the Improvement of Visual Function

Several parameters have been studied for identifying the visual outcomes after pars plana vitrectomy (PPV) for epiretinal membrane (ERM) peeling. This retrospective study aimed to analyze structural retinal changes with spectral domain-optical coherence tomography (SD-OCT) and their correlations with visual acuity improvement in patients with ERM undergoing PPV. Twenty-one pseudophakic eyes were enrolled in the study. Ophthalmic evaluations included best corrected visual acuity (BCVA) and retinal layer thickness measurements with SD-OCT. The segmentation of the retina was divided into four parts: the inner retinal layer (IRL), composed of an internal limiting membrane, retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer; inner nuclear layer (INL); outer plexiform layer (OPL); and outer nuclear layer (ONL). Correlations between changes in retinal layer thicknesses and BCVA were explored over a 6 month follow-up period. The postoperative thickness decrease of the INL was significantly correlated with thickness changes in all other measured retinal layers (p < 0.001). Non-parametric linear regression showed that postoperative improvement in BCVA was associated with a postoperatively decreased thickness in the IRL (p = 0.021), INL (p = 0.039), and OPL (p = 0.021). In eyes undergoing PPV, postoperative thickness decreases of the IRL, INL, and OPL were correlated with visual acuity improvements. Re-compaction of these retinal layers after relieving ERM-induced traction may be an important factor in postoperative visual function improvement.

Intraretinal microvascular changes after ERM and ILM peeling using SSOCTA

BACKGROUND

To prospectively investigate retinal vascular changes in patients undergoing epiretinal membrane (ERM) and internal limiting membrane (ILM) peeling using swept source optical coherence tomography angiography (SSOCTA).

METHODS

Consecutive patients were grouped based on ERM severity and followed using SSOCTA up to month 3 after surgical intervention. Superficial and deep foveal avascular zone (s/dFAZ) as well as foveal and parafoveal vessel density (VD) were correlated with ERM severity and visual acuity. Differences between groups were evaluated.

RESULTS

Significant correlations were found between ERM severity and baseline sFAZ, dFAZ and best corrected visual acuity (BCVA), central retinal subfield thickness (CST) and ΔCST (r = -0.52, r = -0.43, r = -0.42, r = 0.58, r = 0.39; all p<0.05). Vascular flow parameters did not correlate with age, peeling size, pseudophakia or CST, but correlated with intraretinal cysts presence. No associations of BCVA with any of the OCTA parameters across time were found. Significant differences between ERM severity groups 1 and 2 were found for sFAZ at baseline (p = 0.005) and at the 3-month follow-up (p = 0.014), and for dFAZ at baseline (p = 0.017). Superficial foveal and parafoveal VD were not significantly different between groups (all p>0.05).

CONCLUSIONS

This study clearly shows that ERM severity based on ERM staging has to be taken into account when undertaking studies in patients with idiopathic ERM using SSOCTA. Further, specific changes in the superficial and deep retinal vasculature in eyes undergoing ERM and ILM peeling were found. However, the clinical usefulness and prognostic value for post-surgical treatment BCVA of the SSOCTA-derived variables (sFAZ and dFAZ area, as well as foveal and parafoveal VD) used remains questionable.

Evaluation of retinal vascular structure after epiretinal membrane surgery by optical coherence tomography angiography

PURPOSE

To evaluate the retinal vascular structure before and after the epiretinal membrane (ERM) surgery by optical coherence tomography angiography (OCTA).

METHODS

Twenty-two eyes with ERM (study eyes) had been evaluated by OCTA for superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density (VD) at foveal and parafoveal regions and foveal avascular zone (FAZ) before and after ERM removal surgery. Twenty-two fellow eyes were selected as control group.

RESULTS

Preoperative VD of SCP and DCP were significantly lower in ERM eyes than in controls in both foveal and parafoveal areas (p < 0.05, for all). The difference regressed in SCP (fovea: 18.04 ± 3.1 vs 19.98 ± 18 p = 0.002 and parafovea: 47.33 ± 3.54 vs 49.71 ± 28 p = 0.001), but persisted in DCP (fovea: 17.25 ± 3.52 vs 17.57 ± 4.01 p = 0.856 and parafovea: 50.12 ± 4.35 vs 50.93 ± 3.24 p = 0.791) in study eyes, postoperatively. Superficial and deep FAZ areas were significantly smaller in study eyes than controls. Postoperatively, superficial FAZ area enlarged (0.288 ± 0.10 vs 0.307 ± 0.08 p = 0.012), whereas deep FAZ area did not (0.324 ± 0.09 vs 0.338 ± 0.07 p = 0.435). FAZ area was correlated with the best-corrected visual acuity in ERM eyes.

CONCLUSION

Vascular damage in SCP and DCP was demonstrated by OCTA in eyes with ERM. ERM removal surgery mainly improves superficial changes caused by ERM. Changes in deep retinal flow may be associated with visual outcomes after ERM removal surgery.

Optical coherence tomography angiographic findings of lamellar macular hole: comparisons between tractional and degenerative subtypes

We investigated the microvascular changes in eyes with lamellar macular holes (LMHs) using optical coherence tomography angiography (OCTA), compare them between two subtypes of LMH. Tractional and degenerative LMH were differentiated based on the morphological characteristics of OCT. In OCTA images, foveal and parafoveal vessel density (VD) in the superficial and deep capillary plexus (SCP, DCP) and foveal avascular zone (FAZ) area were measured. Eyes that underwent vitrectomy for LMH were included in subgroup analysis. We analysed 63 LMH (42 tractional and 21 degenerative) eyes and 63 control eyes. Compared with degenerative LMH, tractional LMH had better BCVA (p = 0.010), smaller FAZ area (p = 0.001), and higher foveal VD in the SCP (p = 0.130) and DCP (p = 0.002). In degenerative LMH, better BCVA was associated with greater foveal VD in the SCP (p = 0.040) and DCP (p = 0.005), and parafoveal VD in the SCP (p = 0.006). In subgroup analysis, only the tractional LMH group showed significant increases in foveal and parafoveal VDs in the SCP after vitrectomy (p = 0.001 and p = 0.026, respectively). Significant differences in microvascular changes were noted between tractional and degenerative LMH, suggesting that two subtypes are distinct pathogenetic entities.

Association between individual retinal layer thickness and visual acuity in patients with epiretinal membrane: a pilot study

Purpose

We investigated the correlation between visual acuity (VA) and individual retinal layer thickness in the foveal, parafoveal, and perifoveal regions of patients with an idiopathic epiretinal membrane (ERM).

Methods

One hundred and five subjects presenting with unilateral idiopathic ERM were included in this study. We segmented each patient’s optical coherence tomography (OCT) image into seven layers and calculated the mean layer thickness in the foveal, parafoveal, and perifoveal regions using the Iowa Reference Algorithm. In 105 patients with ERM, we detected correlations between their macular regions’ individual retinal layer thickness and their best corrected VA. Thirty-one of the 105 patients with ERM underwent vitrectomy and completed six months of follow-up. We then compared the 31 surgical patients’ preoperative and postoperative individual retinal layer thickness in each macular region. Additionally, the association between preoperative individual retinal layer thickness in each macular region and VA six months post-surgery in patients with ≥ two Snellen lines of visual improvement was determined.

Results

Multiple linear regression analysis showed that the inner nuclear layer (INL) thickness in the foveal, parafoveal, and perifoveal region were all associated with VA in the 105 patients (R² = 0.344, P < 0.001; R² = 0.427, P < 0.001; and R² = 0.340, P < 0.001, respectively). Thirty-one surgical patients 6 months post-surgery showed significantly decreased thicknesses (P ≤ 0.012) of the foveal INL, inner plexiform layer (IPL), and outer nuclear layer (ONL); the parafoveal retina nerve fiber layer (RNFL), IPL, INL, and ONL; and the perifoveal RNFL, IPL, INL, ganglion cell layer (GCL), outer plexiform layer (OPL), and photoreceptor layer (PRL). We found a weak correlation between postoperative VA and preoperative foveal and perifoveal RNFL thickness (r = 0.404 and r = 0.359, respectively), and a moderate correlation between postoperative VA and preoperative foveal and parafoveal INL thickness (r = 0.529 and r = 0.583, respectively) in the 31 surgical patients (P ≤ 0.047). The preoperative INL thickness in the foveal, parafoveal, and perifoveal regions showed a moderate to strong correlation (r = 0.507, 0.644, and 0.548, respectively), with postoperative VA in patients with ≥ 2 lines of visual improvement (P ≤ 0.038).

Conclusion

We detected a correlation between retinal damage and VA in the parafoveal, perifoveal, and foveal regions. Our results suggest that INL thickness in all macular regions may be a prognostic factor for postoperative VA in ERM patients.

Ocular Blood Flow Changes Impact Visual Acuity Gain after Surgical Treatment for Idiopathic Epiretinal Membrane

Background: Idiopathic epiretinal membrane (iERM) is a common eye disease, which can be treated by surgical removal of the fibrotic tissue. Morphological outcome is generally evaluated by optical coherence tomography (OCT). Here, we investigate the impact of surgery on hemodynamics of the posterior pole, using OCT angiography (OCTA). Methods: Patients with unilateral iERM and indication for treatment were included. OCT and OCTA images of the posterior pole were obtained preoperatively and 3-months after 23G vitrectomy with membrane peeling. Parameters of interest included full retinal perfusion, choriocapillaris perfusion (CCP), Sattler’s layer perfusion (SLP), and Haller’s layer perfusion, which were evaluated longitudinally and also compared to unaffected fellow eyes. Using these parameters, multiple regression analyses were used to predict visual outcomes. Results: Sixty-three iERM eyes were recruited, which initially showed a significant bigger central retinal thickness (p < 0.001) and total macular volume (TMV) (p < 0.001) compared to fellow eyes, while perfusion parameters were alike. Three months later, treated eyes had a statistically significant thicker subfoveal choroid (p = 0.006) and showed an increase of CCP (p = 0.003), while SLP decreased (p = 0.014). Lower preoperative TMV and higher SLP were associated with better postoperative visual outcome. Conclusion: In this OCTA study, iERM itself does not affect the choroidal circulation. However, preoperative choroidal circulation will be a biomarker to know the influence on the choroidal circulation after ERM surgery and may be considered as a predictor for visual outcome.

Association of retinal vessel density with retinal sensitivity in surgery for idiopathic epiretinal membrane

PURPOSE

The success of surgical treatment for idiopathic epiretinal membrane (ERM) is measured by postoperative best-corrected visual acuity (BCVA), metamorphopsia, and foveal retinal sensitivity (RS).This study searched for predictive biomarkers of surgical success by determining the association between foveal RS and various aspects of vessel density (VD) in the fovea of patients with ERM.

METHODS

The study examined 25 eyes of 25 patients with ERM who underwent 27-gauge microincision vitrectomy surgery (MIVS). RS was measured with microperimetry (MP-3; NIDEK) at four central points in the fovea with an interpoint distance of 2°. VD was measured with SD-OCT (RS 3000; NIDEK) within the 1-mm² square defined by the 4 RS points at various depths, including the superficial and deep retinal capillary plexus (SCP and DCP, respectively).

RESULTS

Though VD did not change throughout the follow-up period, BCVA and RS significantly improved 1 and 3 months after surgery, respectively (both P < 0.0017). Postoperative RS at 6 months was positively correlated with postoperative DCP VD at 1, 3, and 6 months (r = 0.62, P = 0.001; r = 0.40, P = 0.049; r = 0.53, P = 0.007, respectively), but not with SCP VD at any time point. Multiple regression analysis confirmed that postoperative RS at 6 months was associated with postoperative DCP VD at 1 month (P = 0.03).

CONCLUSION

Higher postoperative DCP VD at 1 month contributed to better postoperative foveal RS at 6 months. Early postoperative VD in the fovea might be a useful predictive biomarker of late postoperative RS in the fovea in ERM patients.