Swept-Source Optical Coherence Tomography Correlations Between Retina and Choroid Before and After Vitrectomy for Epiretinal Membranes

Comparison of the morphological characteristics of the choroidal sublayer between idiopathic macular holes and epiretinal membranes with automatic analysis

PURPOSE

To compare the choroidal sublayer morphologic features between idiopathic macular hole (IMH) and idiopathic epiretinal membrane (iERM) on spectral-domain optical coherent tomography (SD-OCT) using an automatic segmentation model.

METHODS

Thirty-three patients with idiopathic IMHs and 44 with iERMs who underwent vitrectomies were involved. The enhanced depth imaging mode of SD-OCT was used to obtain the B-scan image after single line scanning of the macular fovea. The choroidal sublayer automatic analysis model divides the choroidal into the choroidal large vessel layer, the middle vessel layer and the small vessel layer (LVCL, MVCL and SVCL, respectively) and calculates the choroidal thickness (overall, LVCL, MVCL and SVCL) and vascular index (overall, LVCL, MVCL and SVCL). The morphological characteristics of the choroidal sublayer in the ERM eyes and the IMH eyes were compared.

RESULTS

The mean choroidal thickness in the macular centre of the IMH eyes was significantly thinner than that of the ERM eyes (206.35 ± 81.72 vs. 273.33 ± 82.31 μm; P < 0.001). The analysis of the choroidal sublayer showed that the MVCL and SVCL macular centres and 0.5-1.5 mm of the nasal and temporal macula were significantly thinner in the IMH eyes than in the ERM eyes (P < 0.05), and there was a difference in the macular centre of the LVCL between the two groups (P < 0.05). In contrast, the choroidal vascular index of the macular centre in the IMH eyes was significantly higher than that in iERM eyes (0.2480 ± 0.0536 vs. 0.2120 ± 0.0616; P < 0.05). There was no significant difference in the CVI of other parts of the macula, the LVCL or MVCL between the two groups.

CONCLUSION

The choroidal thickness of the IMH eyes was significantly thinner than that of the iERM eyes, which was mainly observed in 3 mm of the macular centre and the MVCL and SVCL layers of the choroid. The choroidal vascular index of the IMH eyes was higher than that of the iERM eyes. These findings suggest that the choroid may be involved in the pathogenesis of IMH and iERM.

Effects of physiological fluctuations on the estimation of vascular flow in eyes with idiopathic macular pucker

OBJECTIVES

To evaluate the macular vascular flow in eyes with idiopathic macular pucker (EyeiMP), pre and post pars plana vitrectomy with epiretinal and limiting membranes peeling, and to compare it with the vascular flow in the healthy fellow eyes (Eyefellow), taken as physiological reference value.

METHODS

40 eyes of 40 patients were recruited. Best-corrected visual acuity (BCVA) was evaluated. Spectral domain optical coherence tomography (SD-OCT) and OCT-angiography parameters were central foveal thickness (CFT), choroidal thickness (CT), foveal avascular zone (FAZ) area, vessel area density (VAD), vessel length fraction (VLF), vessel density index (VDI) of superficial capillary plexus (SCP) and deep vascular complex (DVC), choriocapillaris (CC) flow. Absolute and relative difference calculation was applied to evaluate macular vascular flow in EyeiMP adjusted for physiological changes detected in Eyefellow.

FOLLOW-UP

6 months.

RESULTS

BCVA improved (p = 0.003) in all cases following surgery. CFT reduced postoperatively (p = 0.0138). FAZ area was smaller in EyeiMP than Eyefellow (p = 0.0071) preoperatively and postoperatively it shrank further (p = 0.0027). After surgery, inverse correlation between FAZ area and BCVA was detected (r-0.683). VAD of SCP was pre- and post-operatively higher in EyeiMP than Eyefellow (baseline p = 0.0344, 6th month p = 0.0466). Relative difference of VDI of SCP (p = 0.0096) and CC flow (p = 0.0013) at 6 months reduced. DVC flow changed significantly only in Eyefellow. CT increased post-operatively in both EyeiMP (p = 0.0345) and Eyefellow (p = 0.00423), but relative difference did not change.

CONCLUSIONS

Vascular flow indices monitoring demonstrated significant changes in both eyes: EyeiMP and Eyefellow. Relative difference of vascular flow provided objective estimate of changes due to iMP surgery taking into account physiological changes in Eyefellow.

Short-term postoperative changes in the choroidal vascularity index in patients with a unilateral epiretinal membrane

BACKGROUND

To investigate short-term choroidal structural and vascular changes after epiretinal membrane (ERM) surgery.

METHODS

In this retrospective study, 65 patients with unilateral ERM underwent pars plana vitrectomy combined with cataract surgery and were examined one day before surgery and one week, one month, and three months after surgery. Choroidal thickness (CT) and choroidal vascular index (CVI) were evaluated using horizontal enhanced depth imaging optical coherence tomography (EDI-OCT) scans and were further calculated using semi-automatic algorithms using MATLAB R2017a.

RESULTS

Preoperatively, CVI was higher in eyes with ERM (61.70 ± 5.17%) than in fellow eyes (59.99 ± 5.26%). CVI increased significantly at one week after surgery (62.14 ± 5.02%) and decreased at 1 and 3 months after surgery (60.76 ± 4.97% and 60.4 ± 4.83%, respectively). The change was pronounced in the nasal region (p < 0.001) and central region (p < 0.05). CT in the temporal macula increased at 1 week (239.65 ± 72.98 μm) after surgery and decreased at 1 and 3 months after surgery (222.15 ± 71.91 μm and 222.33 ± 65.72 μm, respectively; p < 0.01).

CONCLUSIONS

Short-term postoperative variations in the choroid have been demonstrated in eyes with ERM. This may be related to the release of macular traction. CVI assessment using EDI-OCT may be a useful tool for investigating choroidal structural changes accompanying ERM and postoperative period.

Insights into the underlying choroid in different stages of idiopathic epiretinal membranes after Viteromacular surgery

PURPOSE

The purpose of the study was to longitudinally investigate the correlation between choroidal morphologic and vascular parameters and postoperative visual outcome in different stages of idiopathic epiretinal membranes (iERMs).

METHODS

A prospective, observational, institutional case series of 102 consecutive patients diagnosed with unilateral iERMs were recruited at Peking University Third Hospital and were followed up for 12 months after surgical treatment with vitrectomy. Participants were classified into four stages according to current staging scheme. All eligible subjects underwent standardized imaging evaluation of choroidal parameters including subfoveal choroidal thickness (SFCT), choroidal vascularity index (CVI), and choroidal capillary perfusion (CCP) at baseline and each follow-up by enhanced depth optical coherence tomography (EDI-OCT) and OCT angiography (OCTA). Longitudinal follow-up of choroidal parameters over 12 months was analysed, and their correlations with best-corrected visual acuity (BCVA) were also assessed for predictive prognostic value.

RESULTS

CVI and CCP were significantly correlated with BCVA at each follow-up examination (all p < 0.05). However, SFCT exhibited no variation among different stages of iERMs at baseline (p = 0.981) or during follow-up (p = 0.520). The preoperative CVI correlated with 12-month postoperative BCVA (p < 0.001) and its predictive prognostic effect on BCVA was validated in multiple regression analysis (p = 0.006).

CONCLUSION

CVI varied among different stages of iERM and was significantly correlated with visual outcomes after the surgery. CVI could serve as a predictive prognostic marker in iERMs, which further indicates the underlying choroid should be taken into consideration in clinical evaluation of iERMs.

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.

The influence of retinal oxygen saturation and choroidal volume on postoperative outcomes in patients with epiretinal membrane

Purpose

To investigate the effects of vitrectomy (Vy) with or without same time cataract surgery and membrane plus internal limiting membrane peeling (MP+ILMP) on retinal oxygenation and choroidal volume and their role on postoperative outcome.

Methods

Thirty‐two eyes were included in this prospective clinical study. All patients received 23 gauge Vy+MP+ILMP without endotamponade. Additional cataract surgery was performed in 14 patients. Follow‐up visits were scheduled at day 1, week 1, month 1 and month 3. At each visit, best corrected visual acuity (BCVA) using ETDRS charts (except at day 1), oxygenation of retinal vessels using the Oxymap T1, and optical coherence tomography (OCT, Heidelberg Spectralis) was performed.

Results

Mean BCVA increased significantly from 73 ± 11 letters to 77 ± 7 letters at month 3 (p = 0.02). Mean central retinal thickness (CRT) decreased from 456 ± 84 µm at baseline to 418±58µm (p = 0.01 baseline versus month 3). In the cataract surgery group, CRT was higher at month 3 than in the group without (400 ± 58 µm versus 441 ± 51 µm; p = 0.007). There was no statistically significant difference in choroidal volume or oxygenation of retinal vessels between groups (additional cataract surgery versus vitrectomy alone). Oxygenation of retinal arteries tended to decrease at day 1 followed by an increase, but the changes did not reach the level of significance (p = 0.29 baseline versus month 3). Oxygenation of retinal veins increased significantly (p = 0.02 baseline versus month 1; p = 0.04 baseline versus month 3, accordingly). There was a significant negative correlation (Spearman correlation coefficient rs = −0.35, p = 0.047) between visual acuity and oxygenation of retinal veins at month 3. No statistically significant correlation was found between CRT and oxygenation of neither retinal arteries nor veins. Choroidal volume (CV) of the central mm did not change significantly during the study period (baseline: 0.203 ± 0.04 mm³, median: 0.206, month 3: 0.205 ± 0.04 mm³, p = 0.54). There was no statistically significant effect of choroidal volume at baseline on postoperative clinical outcomes (change in BCVA estimate [95% CI]: 7 [−76; 90], p = 0.86; change in CRT: 147 [−577; 871], p = 0.68).

Conclusion

Oxygen saturation may affect the visual acuity outcome but not the CRT in patients after vitrectomy for epiretinal membrane. Choroidal thickness had no statistically significant influence on the study outcomes. Further studies are needed to evaluate if the measurement of retinal oxygenation may be helpful in the decision for surgery.

Choroidal Blood Flow After Intravitreal Ranibizumab in Vitrectomized and Non-Vitrectomized Eyes with Diabetic Macular Edema

Aim

Diabetic retinopathy staging system and progression predictors are soon to be considered insufficient for ophthalmologic practice. Given the growing evidence of the role of choroidal dysfunction, our purpose was to assess choroidal vascular changes with intravitreal ranibizumab (RBZ) treatment in diabetic macular edema (DME).

Methods

This was a prospective longitudinal cohort study. The study included DME eyes, grouped in vitrectomized (group 1) and non-vitrectomized (group 2) eyes, submitted to RBZ in a pro re nata regimen, with 24 weeks of follow-up. Main outcome measures such as central subfield foveal thickness (CFT), choroidal thickness (CT), and choroidal vascular index (CVI) were obtained from structural OCT, and choriocapillaris flow density (CCD) was obtained from OCT angiography and analyzed before and after treatment.

Results

Thirty-one patients were included, 10 eyes in group 1 and 24 eyes in group 2. The mean number of injections was 5.18 (range 2–6). Globally, there was an improvement in BCVA (+4.3 ETDRS letters, p=0.004) and CFT (−84.6 µm, p<0.001) with no changes in CT, CVI, or CCD (p>0.05). When considering only group 2, there was a significant decrease in CT (p=0.033) and a significant increase in CCD (p=0.010) 6 months after treatment, with no differences in CVI (p=0.111). Baseline CVI was correlated with visual acuity at week 24 both globally (r=0.406, p=0.029) and in group 2 (r=0.604, p=0.004).

Conclusion

In non-vitrectomized eyes, choriocapillaris blood flow improves with RBZ. Baseline CVI may correlate with visual function after RBZ. ClinicalTrials.gov NCT04387604.

The Postoperative Course of Choroidal and Central Retinal Thickness in Epiretinal Membranes with Respect to Membrane Severity

INTRODUCTION

The aim of this study was to evaluate the relation between choroidal thickness (CT), central retinal thickness (CRT) and best-corrected visual acuity (BCVA) after surgery for idiopathic epiretinal membrane (iERM).

METHODS

Patients with 4 severity stages of iERM, who underwent vitrectomy with membrane- and internal limiting membrane peeling, were included in this prospective study. CRT, CT, and BCVA were assessed at baseline (BSL), 1 week, 1 and 3 months postoperatively.

RESULTS

Twenty-one eyes were phakic, 11 eyes pseudophakic at BSL, in 14 cases combined cataract surgery was performed. BCVA was highest in stage 1 and 2, lowest in stage 4 iERM (p < 0.001) and correlated with CRT. After surgery, CRT decreased and BCVA increased significantly (p < 0.05). CT did not show significant differences among stages (p = 0.23). BSL CRT did not differ between phakic and pseudophakic eyes, the least reduction after surgery was detected in patients who underwent combined cataract surgery and vitrectomy. BSL CT was greater in phakic than in pseudophakic eyes (p = 0.033). Postoperative CT decreased in pseudophakic and phakic eyes, but remained higher after combined surgery (p = 0.0048).

CONCLUSION

CT is not related to the severity of iERM. Choroidal changes did not influence the BCVA. Additional cataract surgery seems to cause longer recovery in CT and CRT.

En face image-based classification of diabetic macular edema using swept source optical coherence tomography

This retrospective study was performed to classify diabetic macular edema (DME) based on the localization and area of the fluid and to investigate the relationship of the classification with visual acuity (VA). The fluid was visualized using en face optical coherence tomography (OCT) images constructed using swept-source OCT. A total of 128 eyes with DME were included. The retina was segmented into: Segment 1, mainly comprising the inner nuclear layer and outer plexiform layer, including Henle’s fiber layer; and Segment 2, mainly comprising the outer nuclear layer. DME was classified as: foveal cystoid space at Segment 1 and no fluid at Segment 2 (n = 24), parafoveal cystoid space at Segment 1 and no fluid at Segment 2 (n = 25), parafoveal cystoid space at Segment 1 and diffuse fluid at Segment 2 (n = 16), diffuse fluid at both segments (n = 37), and diffuse fluid at both segments with subretinal fluid (n = 26). Eyes with diffuse fluid at Segment 2 showed significantly poorer VA, higher ellipsoid zone disruption rates, and greater central subfield thickness than did those without fluid at Segment 2 (P < 0.001 for all). These results indicate the importance of the localization and area of the fluid for VA in DME.

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.

Retinal applications of swept source optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA)

The advent of optical coherence tomography (OCT) revolutionized both clinical assessment and research of vitreoretinal conditions. Since then, extraordinary advances have been made in this imaging technology, including the relatively recent development of swept-source OCT (SS-OCT). SS-OCT enables a fast scan rate and utilizes a tunable swept laser, thus enabling the incorporation of longer wavelengths than conventional spectral-domain devices. These features enable imaging of larger areas with reduced motion artifact, and a better visualization of the choroidal vasculature, respectively. Building on the principles of OCT, swept-source OCT has also been applied to OCT angiography (SS-OCTA), thus enabling a non-invasive in depth-resolved imaging of the retinal and choroidal microvasculature. Despite their advantages, the widespread use of SS-OCT and SS-OCTA remains relatively limited. In this review, we summarize the technical details, advantages and limitations of SS-OCT and SS-OCTA, with a particular emphasis on their relevance for the study of retinal conditions. Additionally, we comprehensively review relevant studies performed to date to the study of retinal health and disease, and highlight current gaps in knowledge and opportunities to take advantage of swept source technology to improve our current understanding of many medical and surgical chorioretinal conditions. We anticipate that SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift to more widespread adoption of new imaging technology to clinical practice.

Choroidoscleral Interface Irregularity Index: A novel optical coherence tomography-based parameter in patients with epiretinal membrane

This study aimed to assess the regularity of the choroidoscleral interface (CSI) using a novel parameter, CSI irregularity index, before and after epiretinal membrane (ERM) surgery. This study included 36 patients with idiopathic ERM who underwent pars plana vitrectomy and ERM removal. All subjects underwent ocular examinations at baseline and at 1, 2, 4, and 6 months after surgery. The regular contour of the CSI was found in 14 patients (38.9%); mean CSI irregularity index was 14.84 ± 11.01 in this group. The irregular contour of the CSI was found in 22 patients (61.1%); mean CSI irregularity index was 33.96 ± 20.64 in this group. The CSI irregularity index decreased gradually after ERM surgery, and was correlated with postoperative best-corrected visual acuity. The CSI irregularity index could serve as a surrogate marker to quantitatively represent the CSI morphology. We observed the gradual decrease of the CSI irregularity index after ERM surgery in quantitative manner. This study showed correlations between the CSI irregularity index and visual outcomes after ERM surgery. Our results suggest that the CSI irregularity index might be an intuitive anatomic indicator of the CSI and might be useful as a possible prognostic marker for patients undergoing ERM surgery.

Exploring choroidal angioarchitecture in health and disease using choroidal vascularity index

The choroid is one of the most vascularized structures of the human body and plays an irreplaceable role in nourishing photoreceptors. As such, choroidal dysfunction is implicated in a multitude of ocular diseases. Studying the choroid can lead to a better understanding of disease pathogenesis, progression and discovery of novel management strategies. However, current research has produced inconsistent findings, partly due to the physical inaccessibility of the choroid and the lack of reliable biomarkers. With the advancements in optical coherence tomography technology, our group has developed a novel quantitative imaging biomarker known as the choroidal vascularity index (CVI), defined as the ratio of vascular area to the total choroidal area. CVI is a potential tool in establishing early diagnoses, monitoring disease progression and prognosticating patients. CVI has been reported in existing literature as a robust marker in numerous retinal and choroidal diseases. In this review, we will discuss the current role of CVI with reference to existing literature, and make postulations about its potential and future applications.

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.].

Choroidal vascularity index changes after vitreomacular surgery

PURPOSE

To study the structural changes in the choroid using swept-source (SS) optical coherence tomography (OCT), a tool for the choroidal vascularity index (CVI) following epiretinal membrane removal.

METHODS

Fifty-two eyes of 26 patients were evaluated in this prospective, single-centre, observational study. Twenty-six eyes underwent vitrectomy for epiretinal membrane removal (VT-group), and the control group consisted of 26 corresponding fellow eyes (F-group). All patients were evaluated at baseline, 30 and 90 days postsurgery. Using a modified image binarization algorithm for SS-OCT scans, the subfoveal choroidal area was segmented into the luminal and stromal areas, and the CVI was measured by calculating the proportion of the luminal area (LA) to the cross-sectional choroid area.

RESULTS

The mean CVI in the VT-group was 63.86 ± 4.04% at the baseline, 62.45 ± 4.21% at 30 days postsurgery and 61.06 ± 3.79% at 90 days (p < 0.001). The F-group had a mean CVI of 61.12 ± 2.29% at the baseline, 60.91 ± 2.25% at 30 days postsurgery and 61.05 ± 2.28% at 90 days (p = 0.29).

CONCLUSION

The CVI decreases following epiretinal membrane removal when compared to the fellow eyes, which suggests structural changes in the vascular layers of the choroid. The implication of these results may be that secondary inflammation resulting from mechanical traction induces choroidal thickness by way of increased vascularization of the choroid.

Clinical significance of ectopic inner foveal layers in patients with idiopathic epiretinal membranes

BACKGROUND/OBJECTIVES

To evaluate the relationship between the presence of ectopic inner foveal layers (EIFL), choroidal thickness, and visual acuity (VA) in patients with epiretinal membranes (ERM) staged by spectral-domain optical coherence tomography (SD-OCT).

SUBJECTS/METHODS

A total of 242 eyes of 121 patients with unilateral idiopathic ERM were prospectively evaluated. ERM stages were defined based on the SD-OCT staging system as stage 1: negligible morphological or anatomical disruption, retinal layers, and foveal pit are identified; stage 2: characteristic stretching of the outer nuclear layer, absence of foveal depression, retinal layers are identified; stage 3: continuous EIFL crossing the central foveal area, absence of foveal depression, retinal layers are identified; and stage 4: anatomical disruption of the fovea, continuous EIFL crossing the entire foveal area, retinal layers are distorted.

RESULTS

Of 121 eyes with ERM, 23.1% had stage 1, 26.5% had stage 2, 39.7% had stage 3, and 10.7% had stage 4 disease. VA was better in eyes with stage 1 or 2 ERM than stage 3 or 4 ERM (p < 0.001). VA in logMAR was positively correlated with central foveal thickness (r = 0.557, p < 0.001) and EIFL thickness (r = 0.526, p < 0.001), but not with an outer nuclear layer thickness (r = 0.233, p = 0.123). In multivariate analysis, the presence of EIFL was an independent predictor of VA in eyes with ERM (p < 0.001). The presence and stage of ERM did not have a significant effect on choroidal thickness (p > 0.05).

CONCLUSIONS

The SD-OCT staging system according to the presence of EIFL is effective for grading retinal damage and visual loss in eyes with ERM.

Factors affecting foveal avascular zone in healthy eyes: An examination using swept-source optical coherence tomography angiography

OBJECTIVE

To examine factors affecting foveal avascular zone (FAZ) area in healthy eyes using swept-source optical coherence tomography angiography (OCTA).

METHODS

This prospective, cross-sectional study included 144 eyes of 144 individuals (77 women, 67 men) with a best corrected visual acuity of at least 20/20 and no history of ocular disorders. The area of the superficial FAZ was assessed using OCTA. Age, gender, central retinal thickness (CRT), retinal vascular density, refractive error, and axial length were examined to determine associations with FAZ area.

RESULTS

The mean age of the subjects was 42.1 ± 20.2 years (range: 10-79 years). The mean FAZ area was 0.32 ± 0.11 mm2, while the mean retinal vascular density was 35.53 ± 0.92%. Multivariate regression analysis was performed using FAZ area as the dependent variable and age, gender, CRT, retinal vascular density, refractive error, and axial length as independent variables. The results of this analysis demonstrate that CRT and retinal vascular density were significantly associated with FAZ area in our sample (P < 0.001, R2 = 0.425). Age, gender, refractive error, and axial length were not significantly correlated with FAZ area, while CRT and retinal vascular density were negatively correlated with FAZ area (CRT: P < 0.001, R2 = 0.356; retinal vascular density: P < 0.001, R2 = 0.189).

CONCLUSIONS

OCTA results suggest that CRT and retinal vascular density negatively affect FAZ area in healthy eyes.