Comparison of photoreceptor outer segment length in diabetic and idiopathic epiretinal membranes

Epiretinal membrane: an overview and update

Epiretinal membrane (ERM) is a frequently diagnosed macular disease associated with aging, characterized by a fibrous membrane forming on the internal limiting membrane (ILM) and leading to visual dysfunctions such as metamorphopsia. Various hypotheses regarding the pathology of metamorphopsia have been proposed; however, the complete pathophysiologic mechanism underlying ERM remains unclear. Optical coherence tomography (OCT) provides detailed images enabling precise diagnosis and characterization of ERM, with several recent studies using the latest OCT imaging techniques. Surgical removal of ERM is the only treatment option; however, criteria for surgical intervention are not established, complicating the decision-making processes. Furthermore, the debate on whether simultaneous peeling of the ILM during ERM surgery enhances outcomes or poses unnecessary risks is ongoing, with no definite conclusion having yet been reached. This review also focuses on epiretinal proliferation, which is different from ERM and is characteristic of lamellar macular hole (LMH). Recently, diagnostic criteria for LMH and related diseases were proposed. Reports on effective surgical procedures for LMH exist, although more research is needed to confirm the long-term outcomes. Thus, this review article aims to provide an overview and updated knowledge of ERM, LMH, and related diseases.

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.

Evaluation of the optical coherence tomography findings of patients with idiopathic epiretinal membrane

BACKGROUND

This study aimed to determine the relationship between basal visual acuity (VA) and basal optical coherence tomography (OCT) parameters of patients with idiopathic epiretinal membrane (iERM).

METHODS

The study included 200 eyes of 200 patients with iERM. In the evaluation of basal VAs, logMAR 0.3 (0.5 on Snellen chart) was accepted as the limit, and the patients were divided into two groups as Group 1 with VA values below logMAR 0.3 and Group 2 with those above logMAR 0.3. Using OCT, the ellipsoid zone (EZ), interdigitation zone (IZ), external limiting membrane (ELM) integrity, peaked appearance of EZ in the fovea, disorganization of the inner retinal layers (DRIL), central foveal thickness (CFT), maximum retinal thickness (MRT), total photoreceptor length (TPL), photoreceptor outer segment length (PROSL), photoreceptor deformity index (PDI), and inner retinal layer irregularity index (IRLII) were evaluated and compared between the groups.

RESULTS

There were an equal number of patients in Group 1 and Group 2. The preservation of ELM, EZ, and IZ integrity and the peaked appearance of EZ in the fovea were observed at higher rates in Group 1, whereas the rate of DRIL was higher in Group 2 (p < 0.05 for all). In the multiple regression analysis performed to evaluate categorical OCT parameters, only the presence of DRIL was found to be significantly associated with VA (p < 0.003). CFT*, MRT*, and IRLII** were significantly lower in Group 1 (*p < 0.001, **p = 0.001). TPU, PROSL, and FDI were similar between the two groups (p > 0.05 for all).

CONCLUSION

According to the multiple regression analysis, only the presence of DRIL was correlated with lower VA values. Among the OCT parameters, an increase in CFT and MRT, as well as the IRLII value moving away from 1 were related to lower VA values.

Choroidal morphologic and vascular features in patients with unilateral idiopathic epiretinal membranes: An optical coherence tomography analysis integrated with assessment of retinal layers

Introduction

Integrated analysis of retinal and choroidal morphologic and vascular features is urgently needed to examine whether and how these two elements interact with each other, thus contributing to visual impairment in patients with idiopathic epiretinal membranes (iERMs).

Methods

An observational retrospective study consisting of 181 patients diagnosed with unilateral iERM between August 2019 and July 2022 was carried out at Peking University Third Hospital. All patients underwent a standardized set of ophthalmologic examinations, including EDI-OCT and OCTA scanning, and were subsequently categorized into four stages according to current classification schemes based on their OCT findings. Altogether, 15 qualitative and quantitative parameters of both the retina (full-layer, inner and outer layers) and choroid were identified.

Results

The results revealed variations in the choroidal vascularity index (CVI) among different stages of iERMs (p < 0.001) for the first time. Distributions of retinal parameters across four stages of iERMs were validated. Correlation analysis between choroidal and retinal parameters showed that the CVI was associated with both inner and outer retinal morphologic biomarkers. Functional damage to retinal integrity was determined to be a strong contributor to visual acuity reduction in iERMs.

Discussion

This study complemented our present understanding of posterior segment structural and vascular alterations in iERMs.

Optical coherence tomography biomarkers of photoreceptor degeneration in retinitis pigmentosa

PURPOSE

Several parameters on optical coherence tomography (OCT) have been suggested as biomarkers for photoreceptor degeneration in retinitis pigmentosa (RP). This study is to compare the spatial distribution of the changes of OCT biomarkers in RP patients.

METHODS

OCT line scans of the horizontal meridian were conducted in 22 eyes of 22 RP patients and 30 eyes of 30 healthy controls. Longitudinal reflectance profiles were obtained using ImageJ at every 5 pixels. The following parameters on OCT were quantitatively measured: (1) relative optical intensity (ROI) of ellipsoid zone (EZ) and interdigitation zone (IZ); (2) thickness of outer nuclear layer (ONLT), photoreceptor (PRT), inner segment (IST) and outer segment (OST). The variations of these parameters across different regions were analyzed.

RESULTS

From fovea to perifoveal region, all the OCT biomarkers declined before disappeared, except IST and IZ-ROI. There was no identifiable declining zone for the IST and IZ-ROI between the normal and disappeared zones in some patients. The most central biomarker was the reduction of OST and IZ-ROI, followed by the PRT, EZ-ROI, then IST and finally ONLT. All these biomarkers had significant correlations with best-corrected visual acuity, except ONLT.

CONCLUSION

In retinitis pigmentosa, EZ-ROI, IZ-ROI, PRT, OST, IST and ONLT are valuable biomarkers of photoreceptor degeneration. Changes of OST and IZ-ROI are located most centrally and may be the early biomarkers.

Functional and Morphological Results of Epiretinal Membrane Surgery in Idiopathic versus Diabetic Epiretinal Membranes

PURPOSE

Idiopathic and diabetic epiretinal membranes (ERM) are different in terms of pathophysiology, etiology, and macular morphology, and thus might respond to surgical treatment differently. We aimed to compare the surgical results of two groups.

METHODS

Retrospective case series study of 71 eyes of 66 patients who underwent pars plana vitrectomy (PPV) due to idiopathic or diabetic ERM with at least 1-year follow-up. Examinations were performed before, and 1, 3, 6, and 12 months after surgery. The average macular thicknesses in nine sectors described by the Early Treatment Diabetic Retinopathy Study (ETDRS) were measured with spectral-domain optical coherence tomography (OCT), and BCVA was evaluated. ERM recurrence rates were investigated.

RESULTS

In both idiopathic and diabetic groups, retinal thickness (RT) changes occurred as long as 12 months after vitrectomy surgery for ERM. However, in the idiopathic group, significant changes were mainly seen in the first 6 months, while in the diabetic group changes slowed considerably between the third and sixth months, but again accelerated (becoming significant) during the last 6 months.

CONCLUSIONS

According to the findings of this study, as compared to those with idiopathic ERM, diabetic patients would likely see continuing benefits from ERM surgery 6 to 12 months post surgery. The BCVA changes of the two groups were similar. ILM peeling decreased ERM recurrence in the idiopathic group but not in the diabetic group.

Macular Choroidal Thickness Changes in Development, Progression, and Spontaneous Resolution of Epiretinal Membrane

BACKGROUND AND OBJECTIVE

To evaluate the association between macular choroidal thickness and the development, progression, and resolution of epiretinal membrane (ERM).

PATIENTS AND METHODS

The patients (n = 38) with unilateral ERM eyes with definitive changes on optical coherence tomography (OCT) and healthy fellow eyes were observed retrospectively. ERM eyes were divided into three groups: Development/new-onset group (n = 14), progression group (n = 13), and resolution group (n = 11). In each group, the average changes of macular choroidal thickness over time in ERM eyes were compared with those in the fellow eyes RESULTS: Choroidal thickness significantly decreased from 174.0 μm at baseline to 132.3 μm at event time (P = .001) in the development group, and from 140.0 μm ± 30.0 μm to 120.5 μm (P = .002) in the progression group. Conversely, a significant increase in choroidal thickness was observed in the resolution group (from 205.2 μm to 222.6 μm; P = .004). The fellow eyes showed no significant changes in choroidal thickness in all three groups.

CONCLUSION

Choroidal thinning in newly developed or significantly progressed ERM eyes and choroidal thickening in spontaneously resolved ERM eyes suggest a clinical implication of choroidal changes in ERM. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:627-634.].

Changes of outer retinal microstructures after photodynamic therapy for chronic central serous chorioretinopathy

PURPOSE

To evaluate the morphological changes in retinal microstructures following modified photodynamic therapy (PDT) for chronic central serous chorioretinopathy.

SUBJECTS AND METHODS

Retrospective study of 21 consecutive eyes (age, 59±8.0 years [mean ± SD]) of 21 patients with chronic central serous chorioretinopathy. Inner foveal thickness (the distance between the internal limiting membrane and external limiting membrane), photoreceptor outer segment (PROS) length at the point without serous retinal detachment and choroidal thickness were assessed with enhanced depth imaging optical coherence tomography before treatment and at 1, 3 and 6 months after modified PDT.

RESULTS

Six eyes had half-dose and 15 eyes had half-fluence PDT. PROS length within the irradiated area was significantly decreased by 3.9% at 1 month compared with that before modified PDT (43.5±5.72 and 40.5±7.53, P=0.020 [paired t-test]) and returned to baseline length at 3 and 6 months (43.0±5.42 and 43.5±4.33 μm [mean ± SD]; P=0.53 and 1.00 [paired t-test]). PROS length of the nonirradiated area at 1, 3 and 6 months after modified PDT did not significantly differ from that before PDT (41.8±6.35, 41.4±5.33, 41.9±4.67 and 42.3±4.26 μm [mean ± SD]; P=0.66, 0.90 and 0.60, respectively [paired t-test]). There was no significant change in inner foveal thickness during the observation period. At all time points, choroidal thickness was significantly thinner than it was before PDT (P<0.001, paired t-test).

CONCLUSION

Modified PDT may cause mild temporary microstructural changes.

Thickness of the retinal photoreceptor outer segment layer in healthy volunteers and in patients with diabetes mellitus without retinopathy, diabetic retinopathy, or diabetic macular edema

Purpose

The purpose of this study was to investigate whether the severity of diabetic disease in the retina is paralleled by changes in the photoreceptor layer.

Methods

This cross-sectional study included healthy volunteers (30 volunteers, 60 eyes) and patients with diabetes (48 patients, 96 eyes). Each patient underwent a single session of spectral domain optical coherence tomography (OCT) in which each retina was imaged twice. On each OCT image, the thickness of the PROS layer was measured at the foveal center and at points 750 μm temporal to and nasal to the center. For statistical analyses, OCT images were assigned to one of the following groups: healthy, diabetes without retinopathy (DM), diabetic retinopathy (DR), or diabetic retinopathy with macular edema (DME).

Results

The mean PROS thickness at the foveal center in the first and second-obtained OCT images was as follows: healthy, 38.5 μm and 38.6 μm; DM, 38.2 μm and 38.2 μm; DR, 35.6 μm and 36.1 μm; DME, 32.6 μm and 32.6 μm. In the first and second-obtained images, significant differences were found between the healthy group and DR and DME (p < 0.05 for all), between the DM group and the DME (p < 0.05 for all), and between the DR group and the DME group (p < 0.05 for all). No significant differences between groups were found at the nasal and temporal locations.

Conclusion

The PROS layer at the foveal center was thinner in patients who had diabetic retinopathy or diabetic macular edema than both the healthy volunteers and diabetic patients without retinopathy.