MEASUREMENT OF RETINAL DISPLACEMENT AND METAMORPHOPSIA AFTER EPIRETINAL MEMBRANE OR MACULAR HOLE SURGERY

RETINAL MIGRATION AND SURGICAL OUTCOME AFTER HEMI-TEMPORAL INTERNAL LIMITING MEMBRANE PEELING VERSUS CONVENTIONAL PEELING FOR MACULAR HOLE: A Multicenter, Randomized, Controlled Trial

PURPOSE

To investigate the anatomical changes and surgical outcomes of hemi-temporal internal limiting membrane (ILM) peeling and conventional ILM peeling for idiopathic macular hole (MH).

METHODS

This randomized controlled trial was conducted at 3 centers and included 50 participants with MHs of <400 µm in minimum diameter for a duration of <6 months. All participants had undergone vitrectomy with either hemi-temporal ILM peeling (Hemi group) or 360° ILM peeling (360° group) with an injection of 5% sulfur hexafluoride gas, with or without simultaneous cataract surgery, from July 2017 to January 2021. The rate of MH closure and distance of retinal migration were examined.

RESULTS

Of 50 eyes randomized in the 3 centers, the Hemi group comprised 23 eyes, the 360° group 23 eyes, and 4 eyes were eliminated from final analysis. There was a significantly higher rate of primary MH closure in the 360° group (Hemi group: 73.9% vs. 360° group: 100%, P = 0.009). Retinal migration to the optic disk on the nasal side was significantly shorter in the Hemi group at 1, 3, and 6 months postoperatively than in the 360° group. There was no significant difference between the two groups in retinal migration to the optic disk on the temporal side.

CONCLUSION

Nasal retinal migration in patients who underwent the hemi-temporal ILM peeling method was significantly less than in those who underwent the 360° ILM peeling method. However, less nasal retinal migration did not contribute to the MH closure rate.

Topographic analysis of retinal and choroidal vascular displacements after macular hole surgery

It has been reported that the retinal vessel and macular region of the retina are displaced after macular hole (MH) surgery. However, there is no detailed information for correlations between retinal and choroidal displacements. We obtained optical coherence tomography angiography (OCTA) and en-face optical coherence tomography (OCT) images from 24 eyes to measure the retinal and choroidal vascular displacement before and after surgery. These images were merged into infrared images using blood vessel patterns. The same vascular bifurcation points were automatically selected for each follow-up image, and the displacements of the bifurcation points were analyzed as a vector unit for prespecified grid regions in a semi-automated fashion. The results showed displacements of the choroidal intermediate vessels and retinal vessels following MH surgery (p = 0.002, p < 0.001). The topographic changes showed inferior, nasal, and centripetal displacement of the retina and inferiorly displaced choroid. The ILM peeling size and basal MH size were significantly associated with the retinal displacement (p < 0.001 and p = 0.010). Additionally, changes in the amount of the choroidal displacement were significantly correlated with that of the retinal displacements (p = 0.002). Clinicians should keep in mind that there might be topographic discrepancies of the displacement between retina and choroid when analyzing them following surgery.

A novel vector field analysis for quantitative structure changes after macular epiretinal membrane surgery

The aim of this study was to introduce novel vector field analysis for the quantitative measurement of retinal displacement after epiretinal membrane (ERM) removal. We developed a novel framework to measure retinal displacement from retinal fundus images as follows: (1) rigid registration of preoperative retinal fundus images in reference to postoperative retinal fundus images, (2) extraction of retinal vessel segmentation masks from these retinal fundus images, (3) non-rigid registration of preoperative vessel masks in reference to postoperative vessel masks, and (4) calculation of the transformation matrix required for non-rigid registration for each pixel. These pixel-wise vector field results were summarized according to predefined 24 sectors after standardization. We applied this framework to 20 patients who underwent ERM removal to obtain their retinal displacement vector fields between retinal fundus images taken preoperatively and at postoperative 1, 4, 10, and 22 months. The mean direction of displacement vectors was in the nasal direction. The mean standardized magnitudes of retinal displacement between preoperative and postoperative 1 month, postoperative 1 and 4, 4 and 10, and 10 and 22 months were 38.6, 14.9, 7.6, and 5.4, respectively. In conclusion, the proposed method provides a computerized, reproducible, and scalable way to analyze structural changes in the retina with a powerful visualization tool. Retinal structural changes were mostly concentrated in the early postoperative period and tended to move nasally.

Comparison of postoperative morphological changes and retinal displacement in diabetic and idiopathic epiretinal membranes

PURPOSE

To compare the postoperative retinal displacement by optical coherence tomography (OCT) in idiopathic epiretinal membranes (iERM) and diabetic epiretinal membranes (dERM).

METHODS

This retrospective study included 36 iERM and 22 dERM cases. In cross-sectional OCT images (B-scan) the presence of foveal pit, subfoveal fluid, cotton ball sign (CBS), intraretinal cystic changes (ICC), disorganization of retinal inner layers (DRILs) and ectopic inner foveal layer (EIFL) were recorded. Central macular thickness (CMT) and EIFL thicknesses were calculated. Retinal displacement was quantified using infrared image of OCT approach consisting of the fovea to disc margin, interarcade distance and perimacular distances.

RESULTS

The presence of subfoveal fluid (p = 0.014) and DRIL (p = 0.02) was significantly higher in the dERM group. CMT decreased significantly in both groups (p˂0.001). The EIFL was significantly thicker in the iERM group compared to the dERM group (p = 0.049), and it decreased significantly in the iERM group postoperatively. In the iERM group, while the fovea-disc margin distance decreased, the interarcade and perimacular distance increased significantly (p˂0.001). In the dERM group, the disc-fovea distance change was not significant (p = 0.082). Significant visual improvement was achieved with vitrectomy in both groups (p˂0.001). In the dERM group, the presence of DRIL was associated with lower pre and post-op visual acuity (VA) (r = 0.596 and p = 0.004 for pre-operative and r = 0.567 and p = 0.007 for post-operative).

CONCLUSION

Significant retinal displacement occurs after vitrectomy in both iERM and dERM. The low VA in the dERM group may be related to the presence of DRILs.

RHOMBUS DEFORMATION OF RETINAL LATERAL DISPLACEMENT AFTER EPIRETINAL MEMBRANE REMOVAL REVEALED BY DIFFEOMORPHIC IMAGE REGISTRATION

PURPOSE

To establish an analysis method using diffeomorphic image registration and evaluate microvascular displacement through epiretinal membrane (ERM) removal.

METHODS

Medical records of eyes that underwent vitreous surgery for ERM were reviewed. Postoperative optical coherence tomography angiography (OCTA) images were converted to the corresponding preoperative images according to a configured algorithm using diffeomorphism.

RESULTS

Thirty-seven eyes with ERM were examined. Measured changes in the foveal avascular zone (FAZ) area showed a significant negative correlation with central foveal thickness (CFT). The average amplitude of microvascular displacement calculated for each pixel was 69 ± 27 µ m in the nasal area, which was relatively smaller than that in other areas. The vector map, which included both the amplitude and the vector of microvasculature displacement, showed a unique vector flow pattern called the rhombus deformation sign in 17 eyes. Eyes with this deformation sign showed less surgery-induced changes in the FAZ area and CFT and a milder ERM stage than those without this sign.

CONCLUSION

The authors calculated and visualized microvascular displacement using diffeomorphism. The authors found a unique pattern (rhombus deformation) of retinal lateral displacement through ERM removal, which was significantly associated with the severity of ERM.

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.

A Novel Method of Quantifying Retinal Displacement Using Ultra-Widefield Fundus Autofluorescence Imaging

PURPOSE

To introduce a novel method of quantifying retinal displacement in three dimensions (3D) using ultra-widefield fundus autofluorescence (UWF-FAF).

DESIGN

Prospective clinical cohort study.

METHODS

Patients with primary macula-off rhegmatogenous retinal detachment (RRD) treated with pneumatic retinopexy (PnR) or vitrectomy were included. Masked graders selected corresponding points on retinal vasculature and retinal vessel printings (RVPs) within Zone 1, a circular region centered on the fovea with a radius extending to the optic disc (OD) center. Two-dimensional (2D) UWF-FAF was projected to 3D using OD and foveal coordinates. Vertical, horizontal, and diagonal distances between corresponding vessel and RVPs were calculated. Vector displacement of the RVPs to vessels were averaged.

RESULTS

A total of 170 retinal vessel-RVP pairs were identified from 54 UWF-FAF images. Mean displacement in Zone 1 was 0.36 ± 0.38 mm, with an absolute mean angle of displacement of 94.93 ± 41.48° and directionality of 191.84 ± 97.39°. Mean Zone 1 displacement was 0.44 ± 0.42mm and 0.21 ± 0.27 mm in vitrectomy (n = 35) and PnR (n = 19) eyes, respectively (P = .041), with no differences in mean angle of displacement/directionality.

CONCLUSIONS

A novel method of quantifying the magnitude and direction of retinal displacement is presented, accounting for the spherical 3D curvature of the eye by using corresponding points on retinal vessels and RVPs using UWF-FAF. This provides a 3D vector of displacement agnostic of a singular fixation point such as the optic disc. Accurately quantifying the magnitude and angle/direction of displacement may allow for a better understanding of the mechanisms involved in retinal displacement in various surgical techniques, and a better assessment of the association with functional outcomes.

EVALUATION OF RETINAL DISPLACEMENT FOLLOWING PRIMARY SCLERAL BUCKLING FOR MACULA-INVOLVING RHEGMATOGENOUS RETINAL DETACHMENT

PURPOSE

To evaluate the incidence and degree of retinal displacement following scleral buckling surgery for macula-involving rhegmatogenous retinal detachment.

METHODS

Retrospective interventional case series comprised of patients treated with primary scleral buckling procedure without gas tamponade for macula-involving rhegmatogenous retinal detachment and imaged postoperatively with fundus autofluorescence imaging between June 1, 2016 and July 25, 2021. Clinical notes, operative reports, fundus autofluorescence photographs, and optical coherence tomography images were reviewed. The presence and degree of retinal displacement were recorded.

RESULTS

Twelve eyes of 11 patients were included. One (8%) eye with an epiretinal membrane demonstrated 0.1 mm of retinal displacement along the superior arcade and in the superotemporal periphery. The remainder of eyes (92%) did not show any identifiable signs of retinal displacement.

CONCLUSION

Retinal displacement does not seem to be a frequent complication of primary scleral buckling surgery for macula-involving rhegmatogenous retinal detachment.

Vascular tortuosity analysis in eyes with epiretinal membrane imaged by optical coherence tomography angiography

Background

This study aimed to evaluate macular vessel tortuosity using optical coherence tomography angiography (OCTA) and its association with visual outcomes in eyes undergoing surgery for epiretinal membrane (ERM).

Methods

The study included 22 consecutive patients who underwent vitrectomy for ERM between May 2019 and July 2020 and OCTA at Osaka University Hospital. All patients underwent ophthalmologic examinations, including swept-source OCTA. Standard vitrectomy was performed, and the patients were followed up for 6 months postoperatively. Distortion of retinal vessels was calculated using two parameters: the actual vessel length in the vessel section (VL) and the direct vessel branching point distance (BD) in the three quadrants (nasal, temporal, and superior-inferior) of the macula. We analyzed the correlation between these parameters and visual outcomes.

Results

Significantly longer VL was found at 1, 3, and 6 months postoperatively (p = 0.006, 0.008, and 0.022, respectively) in the temporal quadrant compared to baseline temporal VL. Significantly shorter VL was found in nasal quadrants at 1 and 3 months (p = 0.046 and p = 0.018) in the comparison of nasal baseline VL. VL/BDs were correlated with the same postoperative best-corrected visual acuity (BCVA) at 1, 3, and 6 months (p = 0.035, 0.035, and 0.042, respectively) in the superior-inferior quadrant. A significant association of changes in VL and BCVA was found at 3 and 6 months postoperatively in the nasal quadrant (p = 0.018 and 0.0455, respectively).

Conclusions

Changes in vascular distortion after ERM surgery can be measured using OCTA. The change in vessels around the macula became more linear; this was associated with visual outcomes after surgery.

Spotlight on the Internal Limiting Membrane Technique for Macular Holes: Current Perspectives

Pars plana vitrectomy has become the standard procedure for primary macular holes (MHs) repair, including the removal of the posterior cortical vitreous, the stripping of eventual epiretinal membranes, and finally an intraocular gas tamponade. During this procedure, peeling the internal limiting membrane (ILM) has been proven to increase closure rates and avoid postoperative reopening in several researches. In fact, even in large MHs more than 400 µm, the advantage of peeling off the ILM was highlighted by better anatomical closure rates. Nevertheless, some authors suggested that ILM peeling is not always essential, because it generates various side effects in retinal structure and function. Furthermore, the ideal amount of ILM peeling and the most effective strategies for removing the ILM are still subject of research. Different surgical modifications have been reported as alternatives to traditional peeling in certain clinical settings, including ILM flaps, ILM scraping, and foveal sparing ILM peeling. As regards large MHs, the introduction of ILM inverted flap appeared as a game changer, offering a significantly higher >90% closure rate when compared to traditional ILM peeling. Modifications to inverted ILM flap procedures have been claimed in recent years, in order to define the best area and direction of ILM peeling and its correlation with functional outcomes. Moreover, several innovations saw the light in the setting of recurrent MHs, such as ILM free flap transposition, inverted ILM flap combined autologous blood clot technique, neurosensory retinal flap, and human amniotic membrane (HAM) plug, claiming higher anatomical success rate also in those complex settings. In conclusion, the aim of this review is to report how the success rate of contemporary macular surgery has grown since the turn of the century, especially for big and chronic MHs, analyzing in which way ILM management became a crucial point of this kind of surgery.

Unsuspected Central Vision Decrease from Macular Ganglion Cell Loss after Posterior Segment Surgery

PURPOSE

To describe a novel post-surgical complication of circumscribed macula ganglion cell loss as an apparent cause of unsuspected vision loss following posterior segment surgery.

METHODS

Patients were seen in referral and were evaluated with comprehensive examination to include optical coherence tomography (OCT) and microperimetry.

RESULTS

All 8 patients had a sudden central vision loss following vitrectomy and many patients suspected the central loss was present even before the eye patch was removed on the first postoperative day. Of the 8, 1 had a vitrectomy with no membrane peeling while the remaining 7 had membrane peeling. The mean post-operative visual acuity was 20/200. The mean ganglion cell layer (GCL) volume was 0.69 µm3 in the involved eye and 1.035 µm3 in the fellow eye (P<.001). The global retinal nerve fiber layer (RNFL) thicknesses in the involved and fellow eyes were 81.3 and 90 µm respectively (P = .08). The outer retinal architecture was unremarkable in the involved eyes and did not appear to explain the poor acuity. The GCL volume loss was not necessarily associated with RNFL thicknesses that were in the abnormal range or in optic nerve pallor. Microperimetry showed severe depression of the threshold sensitivities.

CONCLUSION

Severe loss of the macular ganglion cells may occur after vitrectomy and is associated with central vision loss. The diagnosis is made by having a high index of suspicion when examining OCT B-scan images and by evaluating GCL volumes. The frequency of this occurrence is currently unknown.

Displacement of the retina after idiopathic macular hole surgery with different internal limiting membrane peeling patterns

AIM

To explore retinal displacement after surgical treatment for idiopathic macular hole (IMH) with different internal limiting membrane (ILM) peeling patterns.

METHODS

Totally 22 eyes from 20 patients with IMH were randomly allocated into two groups, N-T group (11 eyes) and T-N group (11 eyes). For patients in N-T group, ILM was peeled off from nasal to temporal retina. For patients in T-N group, ILM was peeled off from temporal to nasal retina. Preoperative, postoperative 1, 3, and 6mo, autofluorescence fundus images were collected for manual measurement of distances of fixed nasal (N), temporal (T), superior (S), and inferior (I) retinal points (bifurcation or crossing of retinal vessels) around the macula to the optic disc (OD). These were respectively defined as N-OD, T-OD, S-OD, and I-OD. The retinal displacement, macular hole closure rate, and best corrected visual acuity (BCVA) were compared between the two groups after surgery.

RESULTS

At postoperative 1, 3, and 6mo, the macula slipped toward the OD, manifested by the decreased T-OD, N-OD, S-OD, and I-OD (P<0.05). No significant difference was found in the T-OD, N-OD, S-OD, and I-OD between N-T group and T-N group. IMH closure rate was 100% both in N-T group and T-N group. There was no significant difference in BCVA between two groups (P<0.05).

CONCLUSION

The macula slips toward the OD after successful macular hole surgery. The two different ILM peeling pattern show similar visual outcome and retinal displacement, which means ILM peeling directions are not the influencing factor of postoperative retinal displacement.

POSTOPERATIVE MOVEMENT OF THE FOVEA AFTER SUCCESSFUL SURGERY IN PATIENTS WITH IDIOPATHIC EPIRETINAL MEMBRANES

PURPOSE

To evaluate the change in the fovea's postoperative location after successful pars plana vitrectomy with combined epiretinal and internal limiting membrane peeling in patients with idiopathic epiretinal membranes (iERMs).

METHODS

In this prospective study 32 eyes of 32 patients with iERMs were followed from baseline before until 3 months after surgery. Study measures included 4-m Early Treatment Diabetic Retinopathy Study best-corrected visual acuity, enhanced-depth imaging-optical coherence tomography, and intraoperative fundus photographs. Foveal movement was assessed by measuring the change in the papillofoveal distance (∆PFD).

RESULTS

Mean ∆PFD in the study eye was -124 µm (±138) and -272 µm (±213) one day and 3 months after surgery, respectively. Mean ∆PFD after 3 months was greater in the study than in the fellow eye (P < 0.001). ∆PFD at Month 3 did not correlate with the internal limiting membrane area peeled (P = 0.78).

CONCLUSION

Foveal movement starts immediately after surgery and causes a statistically significant reduction in PFD after uneventful macular pucker surgery. ∆PFD correlates statistically significantly with baseline best-corrected visual acuity and baseline central retinal thickness. The internal limiting membrane peeling size had no significant effect on the amount of postoperative foveal dislocation.

Comparative study of 1 DD and 2 DD radius conventional internal limiting membrane peeling in large idiopathic full-thickness macular holes: a randomized controlled trial

OBJECTIVE

To compare the surgical outcomes of 1-disc diameter (DD) and 2-DD conventional internal limiting membrane peeling (C-ILMP) in large full-thickness macular holes (FTMHs).

MATERIALS AND METHODS

A prospective randomized controlled trial. One hundred patients with large idiopathic full-thickness macular hole (FTMH) were randomized into C-ILMP and extended C-ILMP (EC-ILMP) groups. The primary outcome was closure rate at 6 months after surgery. Secondary outcomes were visual acuity (VA), closure type, consequence of ILMP and complications.

RESULTS

The mean symptom duration was 12.19 ± 9.64 months. Mean preoperative VA was 1.25 ± 0.37 logMAR. The average minimum linear diameter was 633.05 ± 129.82 µm and basal linear dimension was 1158.49 ± 249.07 µm. The two groups did not differ in term of demographic data. Closure rate was significantly higher in the EC-ILMP group (76.47% vs. 51.02%, 95% CI 7.24-43.66; p = 0.008). There were also no significant differences in closure type, central foveal thickness, dissociated optic nerve fibre layer detection, or change in fovea-to-disc distance. There were also no significant differences in postoperative VA (p = 0.069) or visual improvement (mean 0.39 ± 0.43 logMAR; p = 0.286). According to subgroup analysis, EC-ILMP resulted in a higher closure rate in patients with chronic FTMH for >6 months, (p = 0.008). Furthermore, EC-ILMP resulted in better anatomical closure and visual result in patients with FTMH with macular hole closure index ≤0.5, p = 0.003 and p = 0.010, respectively.

CONCLUSION

Extended C-ILMP yielded a significantly higher closure rate in large FTMHs, but visual outcome did not differ significantly. According to subgroup analysis, extended C-ILMP was more effective in chronic large FTMH with MHCI ≤ 0.5.

Rhegmatogenous retinal detachment: a review of current practice in diagnosis and management

Rhegmatogenous retinal detachment (RRD) is a common condition with an increasing incidence, related to the ageing demographics of many populations and the rising global prevalence of myopia, both well known risk factors. Previously untreatable, RRD now achieves primary surgical success rates of over 80%-90% with complex cases also amenable to treatment. The optimal management for RRD attracts much debate with the main options of pneumatic retinopexy, scleral buckling and vitrectomy all having their proponents based on surgeon experience and preference, case mix and equipment availability. The aim of this review is to provide an overview for the non-retina specialist that will aid and inform their understanding and discussions with patients. We review the incidence and pathogenesis of RRD, present a systematic approach to diagnosis and treatment with special consideration to managing the fellow eye and summarise surgical success and visual recovery following different surgical options.

Association between displacement and thickness of macula after vitrectomy in eyes with epiretinal membrane

The purpose of this cross-sectional retrospective study was to determine the relationship between the retinal displacements and the retinal thickness in eyes with epiretinal membrane (ERM) after vitrectomy with internal limiting membrane (ILM) peeling. To accomplish this, we measured the retinal thickness using optical coherence tomography (OCT) and the retinal displacement using OCT angiography to obtain 3 mm × 3 mm en face images before, and 2, 4, and 8 weeks following the surgery from 20 eyes of 20 patients. The distance between the retinal vessel bifurcations and the fovea was significantly displaced centrifugally and asymmetrically in the 4 quadrants postoperatively (P < 0.001). The foveal avascular zone (FAZ) was significantly enlarged, and the central foveal thickness (CFT) and the inner nuclear layer (INL) thickness were significantly thinner postoperatively. The displacements were significantly correlated with the changes in the FAZ area (r = 0.717, P < 0.001), the CFT (r = − 0.702, P < 0.001), and the INL thickness (r = − 0.702, P < 0.001). In conclusion, the distance between the retinal bifurcations and the fovea was asymmetrically expanded after the surgery and was significantly correlated with the morphological changes. These results indicate that a horizontal macular contraction is correlated with vertical retinal contraction in the eyes with an ERM.

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.

Segmentation errors and motion artifacts in OCT-A associated with epiretinal membranes

OBJECTIVE

To explore segmentation errors, image quality, and motion-associated artifacts in eyes with idiopathic epiretinal membrane (ERM).

METHODS

This is a prospective observational study. We included 39 eyes affected by ERM and 40 eyes from age-matched healthy subjects. Optical coherence tomography-angiography (OCT-A) was performed in both groups. Segmentation was automatically performed by intergraded software. Segmentation was regarded as inaccurate if either border deviated from the correct plane by more than 50 μm. Presence of motion artifacts (blink lines, displacement, stretch artifacts, quilting, vessel doubling) and image quality index were reported.

RESULTS

Quality index score was 7.2 ± 0.9 for the ERM patients. Phakic eyes with ERM had quality index score of 7.71 ± 1.06, and pseudo-phakic eyes with ERM had a quality index score of 7.32 ± 0.85 (p = 0.22). Motion artifacts were 1.22 ± 0.7 in the study cohort. Segmentation was accurate in all healthy subjects (n = 40). Segmentation errors occurred in 64.1% of ERM patients. The inner plexiform layer was the segmentation boundary most prone to inaccurate segmentation, followed by the internal limiting membrane. Segmentation of retinal pigment epithelial layer was accurate in 96.7% of all cases.

CONCLUSIONS

OCT-A image quality cannot be accurately reproduced in pathological conditions, such as in ERM patients, and is prone to motion artifacts and segmentation errors. Incorrect segmentation results in anatomically incorrect en-face OCT-A images and subsequently in false quantification measures.

Negative correlation between retinal displacement and ganglion cell layer thickness changes in eyes with epiretinal membrane

PURPOSE

To examine retinal displacement after vitrectomy with internal limiting membrane peeling for epiretinal membrane treatment, and to determine the correlation between the extent of displacement and the ganglion cell layer thickness changes.

METHODS

Thirty-nine consecutive patients were evaluated. Optical coherence tomography was performed preoperatively, and 2 and 6 months postoperatively. The distance between the fovea, the vessel intersection in the superior nasal, superior temporal, inferior nasal, and inferior temporal macular regions, and the optic disk were measured. Ganglion cell layer thickness was recorded.

RESULTS

The distance from the optic disk to the fovea and the superior nasal and inferior nasal vessel intersections significantly reduced at 2 and 6 months. Ganglion cell layer thickness significantly decreased in all the subfields (except nasal) at 6 months. A significant negative correlation was found between the change in the ganglion cell layer thickness and the movement of the fovea toward the optic disk. The ganglion cell layer thickness changes significantly correlated with retinal displacement.

CONCLUSION

Retinal displacement toward the optic disk was detected after vitrectomy with internal limiting membrane peeling in eyes with epiretinal membrane. Ganglion cell layer thickness significantly reduced in all the subfields (except nasal). The extent of the displacement and the ganglion cell layer thickness changes showed significant negative correlation.

Influence of Postoperative Posture on Macular Slippage after Macula-Off Retinal Detachment: A Randomized Controlled Trial

INTRODUCTION

To evaluate the effect of postoperative posture on the retinal shift after retinal detachment repair.

METHODS

Patients who underwent pars plana vitrectomy (PPV) for macula-off rhegmatogenous retinal detachment (RRD) were included prospectively in the current study. Patients were randomized into two groups: group A included patients who did a log roll postoperatively, and group B included patients who had to lie flat on their backs for 6 h postoperatively before moving into the end position. Patients in group A and patients in group B were reviewed after 3 weeks and after 6 weeks, respectively, and fundus autofluorescence images (FAF) were obtained to visualize the retinal rotation.

RESULTS

The sample included 50 eyes from 49 patients. Retinal shift occurred after RRD repair in 17 patients (34%). There was no statistically significant difference between the two groups (p = 0.94). Postoperative macular shift occurred significantly less often (p  = 0.049) in participants in whom heavy fluid was used in the procedure. Metamorphopsia was reported postoperatively by 10 of 17 patients with retinal shift (p < 0.001).

CONCLUSION

In our study, postoperative posture did not significantly influence postoperative macular slippage after RRD repair. The use of intraoperative heavy liquid appears to be associated with a lower occurrence of retinal shift.

Idiopathic Macular Hole: A Comprehensive Review of Its Pathogenesis and of Advanced Studies on Metamorphopsia

Vitreous anteroposterior traction is an important factor that affects macular hole (MH) formation at the early stage, and vitreous tangential traction can lead to further hole expansion after hole formation. Recent studies have highlighted the significance of Müller cells for the pathogenesis of MH. Since the advent of MH treatment, success rates for MH closure have significantly improved, as has postoperative visual acuity. However, metamorphopsia, an initial and common symptom of MH, still exists. Metamorphopsia is significantly related to the deterioration of visual quality of life and can be used as an independent index to evaluate visual function before and after surgery. In MH patients, metamorphopsia has different manifestations representing different clinical implications. M-CHARTS, as a new means of inspection, can quantify the degrees of metamorphopsia, and with the development of optical coherence tomography (OCT), layer-by-layer scanning of the retinal structure has become possible. These methods enable detailed analysis of the connections between the degree of metamorphopsia and relevant OCT parameters. Preoperative OCT parameters can be used to evaluate the prognosis of the postoperative visual function of MH patients and are therefore of great significance in guiding the treatment of MH patients.

Associations of aniseikonia with metamorphopsia and retinal displacements after epiretinal membrane surgery

PurposeTo determine the correlation of the degree of aniseikonia with the retinal displacements and metamorphopsia in patients that have undergone successful epiretinal membrane (ERM) surgery.MethodsSubjects were 28 eyes with an ERM in 28 patients. The New Aniseikonia Test (NAT) and M-CHARTS were used to quantify the degree of preoperative and postoperative aniseikonia and metamorphopsia. We also evaluated the distance between the intersections of 2 sets of retinal vessels situated vertically or horizontally by using spectral-domain optical coherence tomography (SD-OCT) images in 28 patients.ResultsThe vertical score of M-CHARTS (MV) was not significantly improved, but the horizontal score of M-CHARTS (MH) was significantly improved at 1 week, 1 month, and 3 months postoperatively. The preoperative NAT score was significantly correlated with the preoperative MH. The NAT score at 3 months was significantly correlated with the MH at 3 months and the MV at 3 months. The preoperative NAT score was significantly correlated with the ratio of the vertical retinal displacement at 1 month and at 3 months after surgery. However, the NAT scores did not improve significantly at any postoperative times.ConclusionsThe degree of aniseikonia was significantly correlated with the degree of metamorphopsia and the tangential displacement of the retina after ERM surgery. Aniseikonia is difficult to improve and metamorphopsia may be a more sensitive parameter to detect the functional recovery after successful ERM surgery.

Vascular Displacement in Idiopathic Macular Hole after Single-layered Inverted Internal Limiting Membrane Flap Surgery

Purpose

To compare vascular displacement in the macula after surgical closure of idiopathic macular hole (MH) after single-layered inverted internal limiting membrane (ILM) flap technique and conventional ILM removal.

Methods

This retrospective study included patients who underwent either vitrectomy and ILM removal only or vitrectomy with single-layered inverted ILM flap for idiopathic MH larger than 400 µm from 2012 to 2015. A customized program compared the positions of the retinal vessels in the macula between preoperative and postoperative photographs. En face images of 6 × 6 mm optical coherence tomography volume scans were registered to calculate the scale. Retinal vessel displacement was measured as a vector value by comparing its location in 16 sectors of a grid partitioned into eight sectors in two rings (inner, 2 to 4 mm; outer, 4 to 6 mm). The distance and angle of displacement were calculated as an average vector and were compared between the two groups for whole sectors, inner ring, outer ring, and for each sector.

Results

Twenty patients were included in the ILM flap group and 22 in the ILM removal group. There were no statistical differences between the groups for baseline characteristics. The average displacement in the ILM flap group and the ILM removal group was 56.6 µm at −3.4° and 64.9 µm at −2.7°, respectively, for the whole sectors (p = 0.900), 76.1 µm at −1.1° and 87.3 µm at −0.9° for the inner ring (p = 0.980), and 37.4 µm at −8.2° and 42.7 µm at −6.3° for the outer ring (p = 0.314). There was no statistical difference in the displacement of each of the sectors.

Conclusions

Postoperative topographic changes showed no significant differences between the ILM flap and the ILM removal group for idiopathic MH. The single-layered ILM flap technique did not appear to cause additional displacement of the retinal vessels in the macula.

Insights Into Epiretinal Membranes: Presence of Ectopic Inner Foveal Layers and a New Optical Coherence Tomography Staging Scheme

PURPOSE

To describe the presence of continuous ectopic inner foveal layers associated with epiretinal membranes (ERMs) and to present a new optical coherence tomography (OCT) staging system of ERMs.

DESIGN

Retrospective multicenter observational case series.

METHODS

Clinical charts and spectral-domain OCT images of 194 eyes of 172 consecutive patients diagnosed with ERMs were reviewed and analyzed.

RESULTS

The presence of continuous ectopic inner foveal layers was identified in 63 out of 194 eyes (32.5%) and this morphology was significantly associated with lower visual acuity. ERMs were divided into 4 stages. Stage 1 (43 out of 194 eyes, 22.1%) ERMs were mild and thin and a foveal depression was present. Stage 2 (88 out of 194 eyes, 45.4%) ERMs were associated with widening of the outer nuclear layer and loss of the foveal depression. Stage 3 (51 out of 194 eyes, 26.3%) ERMs were associated with continuous ectopic inner foveal layers crossing the entire foveal area. In stages 1, 2, and 3 all retinal layers were clearly defined on OCT. Stage 4 ERMs (12 out of 194 eyes, 6.2%) were thick and associated with continuous ectopic inner foveal layers. In addition, retinal layers were disrupted. Visual acuity progressively declined from stage 1 through stage 4 (P < .001).

CONCLUSIONS

The presence of continuous ectopic inner foveal layers in ERMs is a newly described OCT finding associated with significant vision loss and is an essential element of a novel OCT-based grading scheme of ERMs that may influence visual prognosis.

Does Internal Limiting Membrane Peeling Size Matter?

Purpose:

A variety of retinal topographical changes occur after internal limiting membrane (ILM) peeling for macular holes including a movement of the fovea toward the optic nerve. This study was carried out to assess the effect of the extent of ILM-peeled area on these changes and postoperative visual acuity.

Methods:

Prospective single-center study of a consecutive series of patients undergoing macular hole surgery. Preoperative and postoperative optical coherence tomography images were used to assess a variety of measures of retinal morphology. Transmission electron microscopy of the peeled ILM was used to assess residual retinal and vitreous side debris. The area of the ILM peeled was calculated from intraoperative images.

Results:

Fifty-six eyes of 56 patients were included. The mean area of ILM peeled was 9.5 mm2 (2.4-28.3 mm2). The mean disc-to-fovea distance (DFD) preoperatively was 3703 μm with a mean reduction of 52 μm postoperatively, representing a change of −1.29% with a wide range of −7.04% to 1.36%. Using stepwise linear regression, ILM-peeled area was significantly associated with a change in DFD ( P < .001), extent of a dissociated optic nerve fiber layer appearance ( P < .001), and postoperative visual acuity ( P = .025). Nasotemporal retinal thickness asymmetry was associated with the minimum linear diameter ( P < .001).

Conclusion:

The ILM-peeled area has a significant effect on changes in retinal topography and postoperative visual acuity separate from macular hole size. Further study is needed to assess the effect of ILM peeled size on visual function and to guide clinical practice.