Retinal outer layer thickness increases after vitrectomy for epiretinal membrane, and visual improvement positively correlates with photoreceptor outer segment length

Idiopathic Epiretinal Membranes - Pathophysiology, Classifications and OCT-Biomarkers

Epiretinal membranes (ERMs) are a common finding in patients with increasing age. Diagnosis and treatment of ERMs have changed dramatically in recent years due to technological advances in ophthalmological care. In recent years, tomographic imaging has allowed for accurate visualization of ERMs and contributed to the growing understanding of the pathophysiology of this condition. The literature review conducted here summarizes recent innovations in diagnosis, classification, and treatment of idiopathic ERMs and specifically addresses novel optical coherence tomography (OCT) biomarkers that allow for the generation of prognoses regarding the clinical postoperative outcome.

Preoperative ocular coherence tomographic prognosticators of visual acuity after idiopathic epiretinal membrane surgery

PURPOSE

To provide a current review of the evidence for the utility of preoperative ocular coherence tomography (OCT) parameters in prognosticating postoperative visual acuity and visual improvement after idiopathic epiretinal membrane surgery. To determine which OCT bio-markers are most useful in this regard and where future studies may apply more emphasis.

METHODS

An extensive search of the PubMed database was performed for studies investigating this relationship. Key search terms included: idiopathic, epiretinal membrane, surgery, peel, vitrectomy, vision, outcomes, visual acuity, ocular coherence tomography, central foveal thickness, foveal contour, foveal morphology, ectopic inner foveal layers, inner retinal layers, inner retinal irregularity index, outer retinal layers, ellipsoid zone, interdigitation zone, photoreceptor outer segment length, central bouquet abnormality, staging, choroidoscleral irregularity, ganglion cell and nerve fibre layers, inner and outer plexiform layers, inner and outer nuclear layers. Forty-nine peer-reviewed articles were included in this review. These consisted of 28 retrospective studies [1-3,13,16-18,20,23-29,32-36,38,40,42-47], 17 prospective studies[6-12,14,19,21,22,30,31,37,41,48,49], 2 reviews [4,39] and 2 systematic reviews [5,15].

CONCLUSION

The weight of literary evidence seems to support photoreceptor integrity as the most consistent OCT marker of better postoperative visual acuity. This includes analysis of ellipsoid and interdigitation zones as well as photoreceptor outer segment length. However, the newer OCT staging system proposed by Govetto et al. (2017) fulfils a need for a clinically useful and evidence-based OCT classification. It may be the way forward in prognosticating ERM surgical outcomes by preoperative stratification. There is insufficient evidence to suggest the other discussed parameters in this review as useful prognosticators of postoperative visual acuity.

Long-Term Follow-Up of Outer Retinal Layers in Patients with Epiretinal Membranes

PURPOSE

This study aimed to investigate the long-term effect of observed epiretinal membranes on the outer retinal layers and visual acuity.

METHODS

It is a retrospective observational study. Subjects with an epiretinal membrane and consecutive optical coherence tomography scans were followed for changes in visual acuity, central macular thickness, ellipsoid zone loss, and outer foveal thickness (OFT).

RESULTS

The study consisted of 24 eyes of 22 patients, with a mean follow-up of 5 ± 1.6 years. The mean visual acuity was slightly worse at the last follow-up (0.22 ± 0.36 LogMAR [20/33] vs. 0.27 ± 0.36 LogMAR [20/36], p = 0.05). Ellipsoid zone loss was found in 37.5% of eyes. Vision loss was associated with initial size of ellipsoid disruption (p = 0.048) and age (p = 0.027). A decrease in OFT was associated with an initially larger zone of ellipsoid disruption (p = 0.006) and an initially thicker OFT (p = 0.011). An epiretinal membrane associated with vitreomacular adhesion within 1,000 μm of the foveal center at baseline was associated with ellipsoid zone loss (p = 0.012) but not with a change in visual acuity.

CONCLUSIONS

Ellipsoid zone changes were common in this study and tended to enlarge over time. Epiretinal membranes associated with vitreomacular adhesion within 1,000 μm of the foveal center may be a risk factor for ellipsoid zone loss.

Baseline visual acuity and interdigitation zone as predictors in idiopathic epiretinal membranes: A retrospective cohort study

OBJECTIVE

Determine which functional and anatomical characteristics may be predictors of final visual acuity in patients with idiopathic ERM (iERM) submitted to pars plana vitrectomy (PPV) with ERM and internal and internal limiting membrane (ILM) peeling.

DESIGN

Retrospective cohort study.

SUBJECTS

Patients with iERM submitted to PPV between 2016 and 2017.

METHODS

Data regarding the best-corrected visual acuity (BCVA) and the characteristics of the retinal layers observed in SD-OCT were collected preoperatively and until 12 months postoperatively. Central macular thickness (CMT), disorganization of the retinal inner layers (DRIL), outer nuclear layer (ONL) thickness, integrity of subfoveal external limiting membrane (ELM), ellipsoid zone (EZ), and interdigitation zone (IZ) were evaluated.

RESULTS

A total of 128 eyes with iERM from 121 patients were included. BCVA improved significantly (p < 0.001). Significant improvement of BCVA, CMT, DRIL, ONL, ELM, and EZ were obtained. The final IZ was not different from baseline until the end of the study. A significant correlation was observed between the baseline BCVA, EZ, IZ, and the postoperative BCVA (p < 0.001). However, only the baseline BCVA and the integrity of the subfoveal baseline IZ were predictive factors for final BCVA (p < 0.005 and p < 0.001, respectively).

CONCLUSION

PPV provides a significant improvement of BCVA and retinal anatomy recovery in iERM eyes. Baseline IZ didn't change during the 12 months following surgery. Baseline BCVA and subfoveal IZ at baseline were prognostic factors for the final BCVA.

Elevated M2 Macrophage Markers in Epiretinal Membranes With Ectopic Inner Foveal Layers

Purpose

To analyze the differences in the vitreous cytokine profiles in epiretinal membrane eyes with and without an ectopic inner foveal layer (EIFL).

Methods

Sixty eyes with epiretinal membrane (32 eyes without EIFL and 28 eyes with EIFL) were included. The vitreous samples were collected during surgery for epiretinal membrane. The cytokine levels of the vitreous were measured using a multiplex bead analysis.

Results

The mean logMAR visual acuity was worse (0.42 vs. 0.37; P = 0.331) and the central foveal thickness was higher in the EIFL group (496.9 µm vs. 434.2 µm; P = 0.007) than they were in the group without EIFL. The mean EIFL thickness was 164.1 ± 67.7 µm in the EIFL group. On multiplex analysis of the vitreous cytokines, the levels of CD163 (21529 pg/dL vs. 10877 pg/dL; P = 0.002) and macrophage colony-stimulating factor (206 pg/dL vs. 159 pg/dL, P = 0.004) were significantly higher in the EIFL group than they were in the group without EIFL.

Conclusions

Eyes with EIFL had increased vitreous levels of M2 macrophage markers. The activation of glial cell proliferation by M2 macrophages may contribute to EIFL formation.

Phenotypic Characteristics of a French Cohort of Patients with X-Linked Retinoschisis

PURPOSE

To analyze the retinal structure in patients with X-linked retinoschisis (XLRS) using spectral-domain OCT and to correlate the morphologic findings with visual acuity, electroretinographic results, and patient age.

DESIGN

Retrospective, observational study.

PARTICIPANTS

Data from 52 consecutive male patients with molecularly confirmed XLRS were collected retrospectively.

METHODS

Complete clinical evaluation included best-corrected visual acuity, full-field electroretinography, fundus photography, spectral-domain OCT, and fundus autofluorescence. Spectral-domain OCT images were analyzed to determine full thickness of the retina and tomographic structural changes.

MAIN OUTCOME MEASURES

Relationships between age, OCT, and visual acuity were assessed.

RESULTS

One hundred four eyes of 52 patients were included. The mean age at inclusion was 24±15 years (range, 3-57 years). The best-corrected visual acuity ranged from no light perception to 0.1 logarithm of the minimum angle of resolution (mean, 0.6±0.38 logarithm of the minimum angle of resolution). Macular schisis was found in 88% of eyes and macular atrophy was found in 11% of eyes, whereas peripheral schisis was present in 30% of eyes. A spoke-wheel pattern of high and low intensity was the most frequently observed fundus autofluorescence abnormality (51/94 eyes [54%]). The b-to-a amplitude ratio on bright-flash dark-adapted electroretinography was reduced significantly in 45 of 64 eyes (70%). Spectral-domain OCT was available for 97 eyes and showed foveoschisis in 76 of 97 eyes (78%), parafoveal schisis in 10 of 97 eyes (10%), and foveal atrophy in 11 of 97 eyes (11%). Mean central macular thickness (CMT) was of 373.6±140 μm. Cystoid changes were localized mainly in the inner nuclear layer (85/97 eyes [88%]). Qualitative defects in photoreceptor structures were found in most eyes (79/97 eyes [81%]), and the most frequent abnormality was an interruption of the photoreceptor cell outer segment tips (79/79 eyes [100%]). Older age correlated well with lower CMT (correlation coefficient [CC], -0.44; P < 0.001) and with lower photoreceptor outer segment (PROS) length (CC, -0.42; P < 0.001). Lower visual acuity correlated strongly with lower PROS length (CC, -0.53; P < 0.001).

CONCLUSIONS

This study underlined the wide variety of clinical features of XLRS. It highlighted the correlation between visual acuity, patient age, and OCT features, emphasizing the relevance of the latter as potential outcome measure in clinical trials.

Reduction of foveal bulges and other anatomical changes in fellow eyes of patients with unilateral idiopathic macular hole without vitreomacular pathologic changes

PURPOSE

To compare the foveal characteristics in fellow eyes (FE) of patients with unilateral idiopathic macular hole without vitreomacular pathologic changes with eyes of healthy controls.

METHODS

Forty-seven FE and 52 eyes of 52 age- and sex-matched healthy controls were studied. Quantitative assessment of the dome-shaped appearance of the hyperreflective lines that represent external limiting membrane (ELM_bulge) and inner outer segment junctions (IS/OS_bulge) were made by optical coherence tomography (OCT) images. Inner retinal complex thickness (IRCT) was quantitatively assessed at 1000 and 2000 μm of the foveal center in nasal and temporal quadrants. Presence of alterations in the inner retinal outer layers and central foveal thickness (CFT) were also analyzed.

RESULTS

Significantly lower ELM_bulge (p < 0.0001; Mann-Whitney test) and IS/OS_bulge (p < 0.001; student t test) and higher cases with COST alterations, expressed as a diffuse line (p < 0.006; Chi² test) were found in FE than control eyes. IRCT were significantly reduced in FE at all the studied locations when comparing to control eyes (p < 0.05; student t test), maintaining anatomical proportionality among locations.

CONCLUSION

FE without pathologic vitreomacular interactions seems to present some central cone alterations that may be related to other causes than vitreomacular traction.

PHOTORECEPTOR OUTER SEGMENT LENGTH AND OUTER FOVEAL THICKNESS AS FACTORS ASSOCIATED WITH VISUAL OUTCOME AFTER VITRECTOMY FOR VITREOMACULAR TRACTION SYNDROME

PURPOSE

To investigate the predictive factors for postoperative best-corrected visual acuity (BCVA) in patients with vitreomacular traction syndrome treated with vitrectomy.

METHODS

The records of 21 patients with 21 eyes that underwent vitrectomy for vitreomacular traction syndrome and followed for at least 12 months were retrospectively reviewed. The BCVA and spectral domain optical coherence tomography findings were investigated preoperatively and at 1, 3, 6, and 12 months postoperatively. Axial length was measured preoperatively. The correlations between 12-month postoperative BCVA and preoperative parameters, including BCVA, age, axial length, central foveal thickness, outer foveal thickness, and photoreceptor outer segment length, were evaluated.

RESULTS

Twelve-month postoperative BCVA was significantly negatively correlated with preoperative outer foveal thickness and photoreceptor outer segment length (outer foveal thickness: P = 0.029, r = -0.501; photoreceptor outer segment length: P = 0.022, r = -0.523, respectively) but not correlated with age, axial length, preoperative BCVA, and preoperative central foveal thickness (age: P = 0.346, r = 0.216; axial length: P = 0.333, r = 0.242; BCVA: P = 0.202, r = 0.290; central foveal thickness: P = 0.065, r = -0.410, respectively).

CONCLUSION

Preoperative outer foveal thickness and photoreceptor outer segment length could be good predictive factors of postoperative BCVA in patients with vitreomacular traction syndrome.

Changes in Inner and Outer Retinal Layer Thicknesses after Vitrectomy for Idiopathic Macular Hole: Implications for Visual Prognosis

Purpose

To investigate sequential post-operative thickness changes in inner and outer retinal layers in eyes with an idiopathic macular hole (MH).

Methods

Retrospective case series. Twenty-four eyes of 23 patients who had received pars plana vitrectomy (PPV) for the closure of MH were included in the study. Spectral domain optical coherence tomography C-scan was used to automatically measure the mean thickness of the inner and outer retinal layers pre-operatively and up to 6 months following surgery. The photoreceptor outer segment (PROS) length was measured manually and was used to assess its relationship with best-corrected visual acuity (BCVA).

Results

Compared with the pre-operative thickness, the inner layers significantly thinned during follow-up (P = 0.02), particularly in the parafoveal (P = 0.01), but not perifoveal, area. The post-operative inner layer thinning ranged from the ganglion cell layer to the inner plexiform layer (P = 0.002), whereas the nerve fiber layer was unaltered. Outer layer thickness was significantly greater post-operatively (P = 0.002), and especially the PROS lengthened not only in the fovea but also in the parafovea (P < 0.001). Six months after surgery, BCVA was significantly correlated exclusively with the elongated foveal PROS (R = 0.42, P = 0.03), but not with any of the other thickness parameters examined.

Conclusions

Following PPV for MH, retinal inner layers other than the nerve fiber layer thinned, suggestive of subclinical thickening in the inner layers where no cyst was evident pre-operatively. In contrast, retinal outer layer thickness significantly increased, potentially as a result of PROS elongation linking tightly with favorable visual prognosis in MH eyes.

Predictive factors for postoperative visual acuity in idiopathic epiretinal membrane: a systematic review

The aim of this study was to review the literature on predictive factors for postoperative visual acuity (VA) in surgery for idiopathic epiretinal membrane (ERM). A systematic review of the literature in the databases of PubMed and Embase was performed. The risk of bias was assessed based on predefined criteria and the results were summarized. In total, 1927 studies were retrieved of which 35 were potentially eligible. Nineteen studies were of adequate quality in terms of bias. Preoperative VA, central foveal thickness (CFT) and inner segment/outer segment (IS/OS) integrity on optical coherence tomography (OCT) were most extensively studied. Other preoperative factors studied were severity of metamorphopsia, several OCT parameters, fundus autofluorescence and multifocal electroretinogram. In the current literature, preoperative VA is the only variable consistently associated with postoperative VA. IS/OS integrity on OCT is probably associated, and the severity of metamorphopsia, cone outer segment tips integrity and fundus autofluorescence are possibly associated with postoperative VA. CFT is not associated with postoperative VA. Further studies with adequate methodological quality are needed to confirm these findings. Therefore, an overall prediction model, including different parameters, is still awaited.