Foveal Microvascular Structures in Eyes with Silicone Oil Tamponade for Rhegmatogenous Retinal Detachment: A Swept-source Optical Coherence Tomography Angiography Study

Quantitative Microvascular Change Analysis Using a Semi-Automated Software in Macula-off Rhegmatogenous Retinal Detachment Assessed by Swept-Source Optical Coherence Tomography Angiography

Objective: To analyze the performance of custom semi-automated software for quantitative analysis of retinal capillaries in eyes with macula-off rhegmatogenous retinal detachment (RRD) and the role of these microvascular measures as potential biomarkers of postoperative visual outcomes. Methods: A prospective, observational, and single-center study was conducted on consecutive patients who underwent 25G pars-plana vitrectomy for primary uncomplicated macula-off RRD. Optical coherence tomography angiography (OCTA) was performed in the fellow and RRD eyes before surgery and in months 1, 3, and 6 after surgery. The preoperative values of the fellow eyes were used as surrogates of macula-off ones. The primary endpoints were the mean vessel diameter index (VDI); vessel area density (VAD); and vessel skeleton density (VSD) at month 6. Results: Forty-four eyes (44 patients) were included in the study. Considering the fellow eyes as a surrogate of preoperative values of macula-off eyes, VDI in superficial (SCP) and deep (DCP) capillary plexuses was significantly reduced at month 6 (p = 0.0087 and p = 0.0402, respectively); whereas VSD in SCP increased significantly from preoperative values (p = 0.0278). OCTA built-in software parameters were significantly reduced from month 1 to month 6 in both SCP and DCP (p values ranged between 0.0235 and <0.0001). At month 6, 25 (56.8%) eyes achieved a best-corrected visual acuity BCVA ≥ 0.3 (LogMAR). The greater the preoperative BCVA, the greater the probability of achieving good visual outcomes (Odds ratio: 11.06; p = 0.0037). However, none of the OCTA parameters were associated with the probability of achieving a BCVA improvement ≥ 0.3. Conclusions: Quantitative evaluation of capillary density and morphology through OCTA and semi-automated software represents a valuable tool for clinical assessment and managing the disease comprehensively.

Macular and Optic Disc Perfusion Changes After Silicone Oil Removal Using Optical Coherence Tomography Angiography: A Prospective Study

AIM

The aim of this study was to prospectively evaluate the changes in macular and optic disc microvascular structures in patients who underwent silicone oil (SO) removal.

MATERIALS AND METHODS

A total of 28 patients scheduled for unilateral SO removal were included in the study. Their fellow eyes served as controls. Optical coherence tomography angiography (OCTA) of the retina (6.0 mm) and disc (4.5 mm) was performed one day before SO removal, and then at 1 week and 1, 3, 6, and 12 months postoperatively. All analyses were conducted using the R programming language, with a p-value <0.05 considered statistically significant.

RESULTS

After silicone oil removal, statistically significant changes were observed in the flow in the outer retina and radial peripapillary capillary (RPC) density for small and all vessels inside the disc. Statistically significant differences between the intervention and control groups were noted in vessel density in both the superficial and deep capillary plexuses and RPC density for small and all vessels.

CONCLUSION

Changes in macular vessel density and radial peripapillary capillary density were observed after SO removal. The latter changes appear to improve after the first postoperative month and continue until the first postoperative year. Notably, these changes were significant between the first postoperative week and 6 and 12 postoperative months (p = 0.0263 and p = 0.021, respectively). Best corrected visual acuity (BCVA) is likely associated with these parameters, indicating that improvement may be observed even one year following SO removal.

Choroidal vascular changes in silicone oil-filled eyes after vitrectomy for rhegmatogenous retinal detachments

INTRODUCTION

The tamponade of silicone oil (SO) can affect both the structure and blood flow of the retina. However, there are few studies on the effect of SO tamponade on choroidal blood flow. Our study aimed to compare the effects of SO tamponade on the choroidal vascular index (CVI) and choroidal thickness (CT) in patients with unilateral rhegmatogenous retinal detachment (RRD) with operated eyes and fellow healthy eyes.

METHODS

We retrospectively collected demographic and clinical data from 36 patients who underwent 23G pars plana vitrectomy and SO tamponade for unilateral complicated RRD. Enhanced depth imaging-optical coherence tomography (EDI-OCT) scans were performed both within 1 week before SO removal and at the last follow-up visit after SO removal. Using ImageJ software, images were binarized to segment the total choroidal area, luminal area, and stromal area, respectively. The CVI was calculated as CVI=(luminal area)/(total choroidal area), and CT was also evaluated.

RESULTS

During SO tamponade, the CVI and luminal area in operated eyes were significantly lower compared to fellow eyes (57.616 ± 0.030 vs. 60.042 ± 0.019, P < 0.0001; 0.909 [0.694; 1.185] vs. 1.091 [0.785; 1.296], P = 0.007). Even after SO removal, the CVI remained lower in operated eyes than in fellow eyes (59.530 ± 0.018 vs. 60.319 ± 0.020, P = 0.031). Both CVI and luminal area were lower in operated eyes before SO removal than after SO removal (57.616 ± 0.030 vs. 59.530 ± 0.018, P = 0.0003; 0.909 [0.694; 1.185] vs. 0.994 [0.712; 1.348], P = 0.028). The duration of SO tamponade was positively correlated with the difference in CVI between fellow eyes and operated eyes during SO tamponade (P = 0.035). Total choroidal area, stromal area, and CT did not differ significantly between fellow eyes and operated eyes or between pre- and post-SO removal.

CONCLUSIONS

SO tamponade reduces CVI and decreases choroidal blood circulation in patients with retinal detachments required vitrectomy combined with SO tamponade. The longer the SO tamponade time, the more CVI reduction. In future work, we will aim to reduce these side effects by shortening the duration of silicone oil filling.

Early vascular changes after silicone oil removal using optical coherence tomography angiography

BACKGROUND

This study evaluated the vascular changes in the macular and peripapillary regions before and after silicone oil (SO) removal in patients with rhegmatogenous retinal detachment.

METHODS

This single-center case series assessed patients who underwent SO removal at one hospital. Patients who underwent pars plana vitrectomy and perfluoropropane gas tamponade (PPV + C₃F₈) were selected as controls. Superficial vessel density (SVD) and superficial perfusion density (SPD) in the macular and peripapillary regions were assessed by optical coherence tomography angiography (OCTA). Best-corrected visual acuity (BCVA) was assessed using LogMAR.

RESULTS

Fifty eyes were administered SO tamponade, 54 SO tamponade(SOT) contralateral eyes, 29 PPV + C₃F₈ eyes, and 27 PPV + C₃F₈ contralateral eyes were selected. SVD and SPD in the macular region were lower in eyes administered SO tamponade compared with SOT contralateral eyes (P < 0.01). Except for the central area, SVD and SPD in the other areas of the peripapillary region were reduced after SO tamponade without SO removal (P < 0.01). No significant differences were found in SVD and SPD between PPV + C₃F₈ contralateral and PPV + C₃F₈ eyes. After SO removal, macular SVD and SPD showed significant improvements compared with preoperative values, but no improvements in SVD and SPD were observed in the peripapillary region. BCVA (LogMAR) decreased post-operation and was negatively correlated with macular SVD and SPD.

CONCLUSIONS

SVD and SPD are decreased during SO tamponade and increased in the macular region of eyes that underwent SO removal, suggesting a possible mechanism for reduced visual acuity during or after SO tamponade.

TRIAL REGISTRATION

Registration date: 22/05/2019; Registration number, ChiCTR1900023322; Registration site, Chinese Clinical Trial Registry (ChiCTR).

Anatomical and functional outcomes of short-term DensironXTRA heavy silicone oil for rhegmatogenous retinal detachments: a comparative case series

To assess the safety and efficacy of short-term DensironXTRA tamponade for repair of complicated rhegmatogenous retinal detachments (RRD). This is a retrospective consecutive case series of patients undergoing pars plana vitrectomy (PPV) with intravitreal DensironXTRA and a comparator group with gas (sulfur hexafluoride (SF₆) or perfluoropropane (C₃F₈)) tamponades by a single surgeon between January 2017 and November 2020 at a tertiary care centre. A total of 121 eyes with DensironXTRA and 81 comparator eyes with a gas tamponade were included. The DensironXTRA group had a significantly higher number of cases with inferior breaks (82% vs. 48%; p < 0.0001) and a history of previous PPV for RRD (64% vs. 12%; p < 0.0001). DensironXTRA was removed after a median period of 70 (IQR: 48.5-105.5) days. There was similar anatomical success in both the comparator gas tamponade and DensironXTRA groups (98.8% vs. 97.5%, p = 0.6506). Although both groups experienced a significant improvement in visual acuity, this change was significantly higher in the comparator gas tamponade group versus DensironXTRA group (p = 0.0017). There was no significant change in IOP in the DensironXTRA group (mean difference - 0.7; 95% CI - 1.753 to 0.331, p = 0.1785). The rates of complications were low and not significantly different between the two groups. There was no evidence for central macular thinning with DensironXTRA compared to the contralateral eye without RRD as well as with DensironXTRA in situ versus after its removal. DensironXTRA is a promising short-term tamponade agent with good anatomical and functional outcomes and low rates of complications for the repair of complicated RRDs.

Macular Parameters Change during Silicon Oil Tamponade for Retinal Detachment Surgery

Background and Objectives: To evaluate possible changes in macular thickness parameters during and after silicon oil tamponade and in pars plana rhegmatogenous retinal detachment surgery. Materials and Methods: Our retrospective study included 34 consecutive patients who underwent 23-gauge retinal detachment surgery with silicon oil tamponade. Central macular thickness (CMT), central macular volume cube (CMV) and average macular thickness cube (AVG) were measured by optical coherence tomography (OCT) before rhegmatogenous retinal detachment surgery with silicon oil tamponade during tamponade (seven days, one month and three months after surgery), and one month after silicon oil removal. Results: In our sample, macular parameters CMT, CMV and AVG in patients who underwent retinal detachment surgery were statistically reduced during silicon oil tamponade (p < 0.05). After silicon oil removal, all parameters recovered, reaching numeric values which were not statistically significant compared to preoperative values. The average span of silicon oil tamponade was 162 +/- 23 days. Conclusions: Silicon oil tamponade during 23-gauge rhegmatogenous retinal detachment surgery leads to a transitory reduction of central macular thickness, central macular volume cube and average macular thickness cube in eyes that underwent retinal surgery. After silicon oil removal, macular parameters returned to preoperative values in most of the patients.

Effect of silicone oil on retinal microcirculation after vitrectomy for rhegmatogenous retinal detachment evaluated by OCT angiography: a literature review

Silicone oil (SO) has been widely used as intravitreal tamponade agent for rhegmatogenous retinal detachment (RRD) and has been occasionally associated with incomplete retinal structural and functional recovery. The use of Optical Coherence Tomography Angiography (OCT-A) has recently attracted significant attention for detailed analysis of retinal capillary plexus and blood flow changes as predicting factors for postoperative outcomes. A detailed literature search was performed in PubMed database until October 2022. The following keywords were used: rhegmatogenous retinal detachment, silicone oil, optical coherence tomography angiography, macular microvasculature, peripapillary capillary plexus, vessel density, and foveal avascular zone. We identified and reviewed 19 studies referring to microcirculation alterations of the retinal capillary plexus as seen on OCT-A in eyes treated by vitrectomy with intravitreal SO for RRD. A comprehensive update revealed variability of microcirculation characteristics of the retinal capillary plexus including the macular and the peripapillary capillaries. Further studies are warranted to clarify the OCT-A values in an attempt to identify the potential effect of SO on retinal tissue in clinical practice. A review of the existing literature sheds light on the effect of SO on retinal capillary plexus and the potential impact on functional outcomes after vitrectomy for RRD. This article discusses important aspects of key publications on the topic, highlights the importance to identify distinct alterations of the microvasculature status, and proposes the need for further future research in this field.

Long-Term Follow-Up of Macular Perfusion Evaluated by Optical Coherence Tomography Angiography after Rhegmatogenous Retinal Detachment Surgery

BACKGROUND

The goal of this study was to investigate macular microvascular changes using optical coherence tomography angiography (OCTA) at one year after successful rhegmatogenous retinal detachment (RRD) surgery.

METHODS

We performed a cross-section study including RRD treated by pars plana vitrectomy (PPV) with or without scleral buckling and SF6 tamponade. After 12 months, DRI-Triton SS-OCTA was performed. Superficial and deep retinal capillary plexuses (SCP and DCP), choriocapillaris (CC) vessel density (VD), and foveal avascular zone (FAZ) morphology were analyzed. Results were compared with the unaffected contralateral eye.

RESULTS

Sixty eyes were included. We observed an increase in VD in the central area of both the SCP and DCP in macula-off eyes treated with PPV + SB and in the SCP of macula-off eyes treated with PPV. Macula-off eyes had a diminished VD for both plexuses in the superior quadrant and in the SCP inferior quadrant in those treated with PPV + SB. The CC flow was diminished in the temporal quadrant of macular-off eyes treated with PPV + SB. Healthy eyes presented higher diameter values than macula-off eyes treated with PPV + SB. FAZ horizontal and vertical diameters were smaller in patients with macula-off RRD vs. macula-on RRD and control groups.

CONCLUSION

Macular vascularity remains almost unchanged one year after successful RRD surgery, irrespective of the surgical technique or prior macular status.

Long-Term Macular Vascular Changes after Primary Rhegmatogenous Retinal Detachment Surgery Resolved with Different Tamponade or Different Surgical Techniques

Background: The aim of this study was to assess long-term macular vascular changes and their correlation with functional recovery in patients successfully treated for Macula-ON and Macula-OFF rhegmatogenous retinal detachment (RRD). Methods: This retrospective observational study included 82 eyes of 82 patients who received primary successful retinal detachment surgery, 33 Macula-ON and 49 Macula-OFF. Superficial and deep capillary plexuses (SCP and DCP) were evaluated by optical coherence tomography angiography (OCTA), and were correlated with visual acuity (VA), surgical technique and tamponade at 12 months after surgery. The fellow eyes were used as controls. Results: At 12-month follow-up, there was a significant decrease in the vessel density (VD) in the SCP in the operated eyes compared to control eyes (p < 0.05) in both the Macula-ON and Macula-OFF groups. Vessel length density (VLD) decrease in SCP was more extended in the Macula-OFF group. No difference in the DCP perfusion parameters was found, compared to controls. Subgroup analysis dependent on the type of surgery or tamponade showed no significant differences of VD and VLD. An inverse correlation was found between the SCP VD and the duration of silicone oil (SO) tamponade (p = 0.039). A significant correlation was observed between parafoveal SCP VD and final best corrected visual acuity (BCVA) (p = 0.028). The multivariate linear regression analysis showed that only the type of tamponade was significantly correlated with the final BCVA in the Macula-ON group (p = 0.004). Conclusions: Our study described long-term perfusion changes in RRD after surgery, with lower SCP VD and VLD in the operated eyes compared to the fellow ones, not influenced by type of surgery or tamponade. The choice of tamponade and SO removal timing may affect functional outcomes, especially in Macula-ON RRD. In conclusion, such functional and perfusion changes can be considered biomarkers that highlight the relevance of careful management of this sight-threatening disease.

Retinal and Corneal Changes Associated with Intraocular Silicone Oil Tamponade

Silicone oils (SO) are used as long-term intraocular tamponades and have an irreplaceable role in vitreoretinal surgery. They can, however, be associated with multiple and potentially severe complications, involving different ocular tissues, in particular retina and cornea. Recent advances in ophthalmic imaging have allowed the precise characterization of retinal and corneal microstructural changes, at a subclinical level. This detailed analysis of SO-related retinal and corneal changes has improved our understanding of their pathogenesis and offer the potential for optimized monitoring and management of patients with SO-filled eyes. This review aims to provide clinicians and ophthalmic scientists with an updated and comprehensive overview of the corneal and retinal changes associated with SO tamponade.

Impact of Silicone Oil Removal on Macular Perfusion

(1) Background: Silicone oil (SO) can be used as an endotamponade during vitreoretinal surgery for retinal detachment. There is emerging evidence that SO filling of the vitreous cavity and its removal may impact macular perfusion. So far, studies have not focused on choroidal sublayer perfusion, yet. (2) Methods: Optical coherence tomography angiography was applied in 19 patients with SO endotamponade before and four weeks after removal of SO. (3) Results: Perfusion of choriocapillaris increased significantly after SO removal, while perfusion of Haller’s and Sattler’s layer decreased significantly. (4) Conclusions: Removal of SO impacts choroidal perfusion and leads to a perfusion shift within choroidal sublayers. This study underlines that it is worth to conduct larger prospective studies that evaluate the choroidal perfusion and its functional implications in more detail.

Rhegmatogenous retinal detachment induces more severe macular capillary changes than central serous chorioretinopathy

To investigate hemodynamic changes in macula-off rhegmatogenous retinal detachment (RRD) and its impact on visual prognosis by comparing with central serous chorioretinopathy (CSC). Using optical coherence tomography angiography (OCTA), vascular density in the superficial capillary plexus and deep capillary plexus (DCP) was retrospectively compared with that in contralateral unaffected eyes in macula-off RRD and CSC eyes. In RRD eyes, pre- and postoperative ultra-widefield (UWF) fluorescein angiography (FA) were obtained to analyze vascular changes. In OCTA, both macula-off RRD and CSC eyes showed less density in macular DCP, compared to the unaffected fellow eyes. Compared to CSC, eyes affected by macula-off RRD showed a reduction in DCP vascular density and an increase in foveal avascular zone area, although it had a much shorter macular detachment period. In macula-off RRD, less density of DCP was strongly correlated with longer duration of detachment, greater ellipsoid zone disruption, and poor visual recovery. In UWF-FA, detached retina showed capillary hypoperfusion, venous stasis and leakage, which were improved after reattachment. In conclusion, macular capillary loss of flow, which was associated with photoreceptor disruption, correlated with duration of detachment in RRD. Early reattachment and reperfusion are required for minimizing macular vasculature and photoreceptor damage in macula-off RRD.

Longitudinal evaluation of retinal thickness and OCTA parameters before and following silicone oil removal in eyes with macula-on and macula-off retinal detachments

BACKGROUND

To investigate the longitudinal retinal vascular and structural alterations by using OCTA following successful repair of retinal detachment (RD) by using silicone oil (SO) endotamponade.

METHODS

A prospective cohort study was performed on 24 eyes of 24 subjects; 17 of them with macula-off and seven with macula-on RD. At least four OCTA scans were generated for each study eye; two before and two after SO removal (SOR). At each session, retinal thickness (RT), vascular density (VD) in the superficial (SCP) and deep capillary plexuses (DCP) and foveal avascular zone(FAZ) size were measured within the fovea, parafovea and whole macular image. The changes in repeated measures of the same parameters especially before and after SOR were performed and compared within macula-on and macula-off groups and between fellow eyes.

RESULTS

"In the macula-off eyes, RT measurements within the whole macula, fovea and parafovea reduced as compared with their fellow eyes(p < 0.0001, p = 0.001 and p < 0.0001, respectively) and did not improve after SOR. Additionally, all of the whole macular, foveal, and parafoveal VD measurements at SCP and foveal VD at DCP were less than their fellow eyes after SOR (p = 0.026, p = 0.023 p = 0.026, and p = 0.002, respectively). In macula-on eyes, RT measurements decreased within the parafovea and whole macular area before SOR (p = 0.018 and p = 0.011, respectively) but improved after SOR. Also, VD measurements did not change during follow-up and were not statistically different than their fellow eyes (p > 0.05). FAZ enlargement was found in eyes with macular-off RD after SOR, whereas it was not observed with macular-on RD (p = 0.038and p = 0.237, respectively).

CONCLUSIONS

Treatment of macula-off RD with SO tamponade has been associated with vascular retinal abnormalities which did not improve following SOR. On the contrary, successful treatment of RD with SO tamponade in macula-on eyes VD measurements of SCP and DCP were not statistically different than their fellow eyes.

Peripapillary changes after vitrectomy and silicone oil tamponade for rhegmatogenous retinal detachment

Purpose:

To evaluate the peripapillary changes after vitrectomy and silicone oil (SO) tamponade in eyes with rhegmatogenous retinal detachment (RRD).

Methods:

In this study, 25-gauge vitrectomy with SO tamponade was performed in 22 eyes with RRD. The radial peripapillary capillary (RPC) vessel density (VD) and retinal nerve fiber layer thickness (RNFLT) were assessed by optical coherence tomography angiography at 2, 4, 8, and 12 weeks postoperatively. The values of healthy fellow eyes were used as controls.

Results:

The global RPC VDs were significantly lower in the eyes with RRD than in fellow healthy eyes at 2 weeks (P < 0.001), and increased at 4 weeks, then decreased over time after surgery (F = 1.046, P = 0.377). The RPC VDs in the superior-hemifield were lower than those in the inferior-hemifield at 12 weeks postoperatively (t = −2.844, P = 0.010). The global RNFLTs decreased gradually after vitrectomy in the eyes with RRD (F = 1.312, P = 0.276). The RNFLTs in the superior-hemifield were thinner than those in the inferior-hemifield at 12 weeks postoperatively (t = −2.222, P = 0.037). The global, superior, and inferior RNFLTs were correlated with corresponding RPC VDs in the eyes with RRD at all time-points postoperatively (P < 0.05).

Conclusion:

RRD resulted in the decrease of RPC VDs. The RPC VDs recovered in the early postoperative period but were still lower than the normal level. Long-term application of SO tamponade resulted in the reduction of peripapillary VDs secondary to loss of RNFLTs.

Association between retinal vessel density and postoperative time after primary repair of rhegmatogenous retinal detachment

The study aimed at a quantitative evaluation of macular vasculature after primary repair of rhegmatogenous retinal detachment (RRD) in correlation with the elapsed postoperative time. Optical coherence tomography angiography (OCT-A) was performed in 66 eyes of 33 patients in a retrospective case-control study: superficial and deep retinal vessel density (VD) of the whole image, fovea, parafovea, non-flow area, and foveal avascular zone (FAZ) were measured. Data of eyes with RRD were compared to the healthy fellow eyes in 3 groups according to the elapsed time after surgery: RD1: 6–12 months (n = 10), RD2: 1–2 years (n = 10), and RD3: 2–10 years (n = 13). In RD1 VD was significantly lower in the superficial parafoveal, deep parafoveal, and deep whole area compared to the fellow eyes. In RD3 VD was significantly lower in the superficial fovea, parafovea, whole image, and deep fovea, the non-flow area was significantly enlarged. OCT-A demonstrated a significant reduction in the superficial and deep regions of the macular vasculature after the repair of RRD. The deep area is more affected in the early postoperative period and the superficial region and the extent of the non-flow area are more involved after a longer postoperative time.

Analysis of the Changes in Retinal Thickness in Eyes Undergoing Vitrectomy with Silicone Oil Tamponade

Purpose: To investigate changes in the retinal layer thickness in rhegmatogenous retinal detachment (RRD) and intraocular foreign body (IOFB) patients undergoing successful pars plana vitrectomy (PPV) with silicone oil tamponade. Methods: This retrospective study included 28 eyes of 28 patients (RRD: 24 patients; IOFB: 4 patients) that were successfully repaired with PPV with silicone oil tamponade. The thickness measurements of the total retina, retinal nerve fiber layer (RNFL), and ganglion cell-inner plexiform layer (GC-IPL) were performed with swept-source optical coherence tomography in nine Early Treatment Diabetic Retinopathy Study subfields, using the wide three-dimensional mode before and after silicone oil tamponade removal. The measurements were compared and differences were analyzed with respect to normal fellow eyes. Results: The RNFL and GC-IPL thickness measurements decreased remarkably as the silicone oil tamponade period progressed, compared with the thickness of the total retinal layer. The average thicknesses of the total retina, RNFL, and GC-IPL were significantly greater in eyes in which the silicone oil had been removed than in those in which the silicone oil remained. Conclusions: Silicone oil tamponade can change the thickness of the retina layer. The longer the silicone oil is tamponaded, the more significant the reduction in thickness of the inner retinal layer.

A decrease in macular microvascular perfusion after retinal detachment repair with silicone oil

AIM

To observe whether silicone oil (SO) tamponade could decrease macular perfusion after retinal detachment repair.

METHODS

A prospective observational case-control study. Patients diagnosed with primary macular off rhegmatogenous retinal detachment undergoing successful retinal repair surgery with vitrectomy were strictly selected. Optical coherence tomography angiography findings were compared between SO and air tamponade groups. Two postoperative visiting points were set (1 and 3mo).

RESULTS

Totally 29 patients (29 eyes) were enrolled. Twenty cases had SO tamponade while 9 cases were with air tamponade. At the first visiting point, superficial parafoveal vessel density (PFSVD) significantly decreased in the SO group (P=0.0403), especially in the superior quadrant or superior-hemi area (P=0.0089, 0.0426, respectively). Parafoveal deep vessel density (PFDVD) had no difference between the two groups. At the second visiting point, all quadrants of PFSVD reduced significantly in the SO group (P=0.0256, 0.0001, 0.0031, <0.0001 in temporal, superior, nasal, and inferior area, respectively), but PFDVD remained no different. In the air group, all areas of PFSVD showed significantly improving from the first visit to the second one (P=0.0324, 0.0001, 0.0371, 0.0026, in temporal, superior, nasal, and inferior area, respectively); however, almost all quadrants of PFDVD showed no changes during this period. In the SO group, both PFSVD and PFDVD showed no obvious changes between the two visiting points. Besides, parafoveal full retinal thickness in the SO group reduced significantly at both visiting points over the air tamponade, while the foveal avascular zone area showed no difference in the two groups.

CONCLUSION

After retinal detachment surgery with vitrectomy and SO tamponade, superficial macular perfusion and full retinal thickness could decrease obviously when compared to air tamponade. This reduction process could persist throughout the tamponade period.

Evaluation of macular vessel density changes after vitrectomy with silicone oil tamponade in patients with rhegmatogenous retinal detachment

AIM

To evaluate macular microvasculature changes in eyes after pars plana vitrectomy (PPV) and intraocular silicone oil (SO) tamponade for macula-off rhegmatogenous retinal detachment (RRD) using optical coherence tomography angiography (OCTA).

METHODS

Totally 19 eyes (19 patients) with macula-off RRD who underwent PPV and intraocular SO tamponade were retrospectively reviewed. The parafoveal superficial capillary plexus (SCP) vessel density (VD), deep capillary plexus (DCP) VD, choriocapillaris plexus (CCP) VD, and foveal macular thickness were evaluated using OCTA throughout 16wk postoperatively. The values of healthy fellow eyes were used as control.

RESULTS

The parafoveal SCP, DCP, and CCP VDs were significant increased over time in RRD eyes during the 12wk postoperatively, then decreased at 16wk postoperatively (all P<0.01). The ratios of RRD eyes and fellow healthy eyes (r/f ratios) of the SCP and DCP VDs were lower than those of the CCP VD postoperatively (all P<0.05). There were not significant differences in the r/f ratios between SCP and DCP VDs postoperatively (all P>0.05).

CONCLUSION

The parafoveal SCP, DCP, and CCP VDs gradually recover over time after PPV surgery with SO tamponade. Long-time SO tamponade might decrease postoperative macular VDs. Compared to parafoveal CCP VD, the parafoveal SCP and DCP VDs were more vulnerable in RRD eyes postoperatively.

Microvascular changes on optical coherence tomography angiography after rhegmatogenous retinal detachment vitrectomy with silicone tamponade

Purpose

We aimed to evaluate microvascular changes on optical coherence tomography angiography (OCTA) in patients with rhegmatogenous retinal detachment (RRD) who underwent silicone oil (SO) tamponade and compare changes according to macular involvement.

Methods

This retrospective study included 48 patients with unilateral RRD who underwent vitrectomy and SO tamponade and were stable after SO removal. Control data were obtained from the fellow healthy eye. Ophthalmic examinations, including best corrective visual acuity (BCVA) and OCTA, were conducted. Differences in vascular density (VD) in different sections of the macula and differences in the foveal avascular zone (FAZ) were analyzed between the affected eyes and control eyes. Subgroup analyses according to macular involvement were performed.

Results

Baseline BCVA and duration of SO tamponade were associated with postoperative BCVA (p<0.001, p = 0.03, respectively). The average VD in the deep capillary plexus (DCP) and the VD of the nasal parafoveal area in both the superficial capillary plexus (SCP) and the DCP decreased relative to those in the control eyes (p = 0.026, p = 0.028, and p = 0.031, respectively). The FAZ area in the DCP and in the SCP also increased when compared with that in the controls (p = 0.043, p = 0.002, respectively). In addition, the macular-off RRD group had lower VD in the nasal parafoveal area of the DCP than the macular-on RRD group.

Conclusion

SO tamponade could cause microvascular changes, especially in the nasal parafoveal area. The macular-off RRD group were affected more than the macular-on RRD group.

OCT-A in the Management of Vitreoretinal Diseases and Surgery

ABSTRACT

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

Functional and Structural Outcomes at the Foveal Avascular Zone with Optical Coherence Tomography Following Macula off Retinal Detachment Repair

Background

Visual recovery following macula involving rhegmatogenous retinal detachment remains poorly understood. The aim of this work is to correlate the functional and the anatomical changes in retinal vasculature in the foveal avascular zone using optical coherence tomography angiography (OCTA) after successful retinal reattachment repair and correlate this data with retinal thickness and post-operative visual recovery.

Methods

A prospective, comparative observational study of 28 eyes of 14 patients with 14 eyes undergoing macula off retinal detachment repair with pars plana vitrectomy, endo-laser and silicone oil-based tamponade compared with 14 fellow healthy eyes at 1, 6 and 12 weeks post-operative period. The study was conducted at the Research Institute of Ophthalmology, Giza, Egypt between February 2018 and August 2018.

Results

The foveal avascular zone (FAZ) area in the patients group was not significantly different compared to the control group and was found to be negatively correlated with the central retinal thickness in both the study and control group. The superficial capillary plexus (SCP) area at the FAZ was significantly larger than the deep capillary plexus (DCP) area at the FAZ in both the study and control group over the follow-up period. The DCP area at the FAZ was significantly larger at the 3rd follow-up than the 1st follow-up. The SCP FAZ area was significantly larger than the DCP FAZ area in both the study and control group over the follow-up period. BCVA was found to be negatively correlated to the retinal thickness of the temporal 3 mm paracentral quadrant with no correlation with central foveal thickness (CFT) and the FAZ area.

Conclusion

Optical coherence tomography (OCT) and OCTA are valuable noninvasive imaging tools to monitor and predict the structural changes at the foveal avascular zone during the recovery phase after successful retinal reattachment involving macula.

Spectroscopic Optical Coherence Tomography for Thin Layer and Foil Measurements

The main goal of this research was to assess if it is possible to evaluate the thickness of thin layers (both thin films on the surface and thin layers below the surface of the tested object) and foils using optical coherence tomography (OCT) for thickness assessment under the resolution of the standard commercially available OCT measurement system. In the proposed solution, light backscattered from the evaluated thin layer has been expressed as a multiple beam interference. Therefore, the OCT system was modeled as a two-beam interferometer (e.g., Michelson), in which one beam propagates from the reference arm and the other comes from a Fabry-Pérot interferometer. As a consequence, the mathematical model consists of the main Michelson interferometer, in which the measuring arm represents the Fabry-Pérot interferometer. The parameters of the layer (or foil) are evaluated by analyzing the minimum value of the interference contrast. The model developed predicts the behavior of the thin layers made from different materials (with different refractive indexes) with different thickness and located at different depths. To verify the correctness of the proposed model, an experiment with a wedge cell has been carried out. The wedge cell was shifted across the scanning beam using a linear translation stage with a micrometer screw under the scanning head. The relationship between the thickness of the gap of the wedge cell and the OCT output signal is presented. For the additional verification of the proposed model, the results of the measurements of the thickness of the thin foil were compared with the theoretical results of the simulations. The film thickness was evaluated based on the calculated positions of the minimum value of interference contrast. A combination of the standard potentialities of OCT with the proposed approach to analyzing the signal produces new metrological possibilities. The method developed allows us to evaluate thickness under the resolution of the system and the location of the layer as well. This produces the possibility of measuring a layer which is covered by another layer. Moreover, it is possible to create a thickness map with high sensitivity to thickness changes. These experiments and simulations are the culmination of preliminary research for evaluating the potential of the proposed measurement method.

Rural-urban differences in myopia prevalence among myopes presenting to Bhutanese retinal clinical services: a 3-year national study

PURPOSE

To determine the prevalence and demographic characteristics of myopia among patients presenting to the national vitreo-retinal (VR) services in Bhutan.

METHODS

The records of the VR clinic at the apex national referral centre, providing the only VR services in the country, were reviewed to identify all new myopia patients over three years. Thus, we surveyed all referrals nationally. The patients were categorised into urban and rural females and males. We assessed myopia prevalence in each group by occupational and educational categories. We examined univariate prevalence data and a multivariate logistic regression (MLR) identified independent factors.

RESULTS

Of 2913 cases 1544 (53.0%) were males. Females presented earlier (mean ±SD): overall 45.7 ± 21.9 cf. 48.6 ± 21.6 years, p = 0.003, and among myopes 23.9 ± 13.5 cf. 27.6 ± 18.6 years, p = 0.032. Myopia constituted 92.1% of refractive error, an overall prevalence of 12.3%. Myopia was more common among females (p = 0.01) and urbanites (p = 0.02). Myopia prevalence was highest among urban females (20.9%), followed by urban males (11.9%), rural females (6.8%), and rural males (5.2%). Logistic regression revealed that the odds of having myopia were increased by being a student (4.96 ×) or professional (1.96 ×), and decreased by rural living (1.75 ×), all p ≤ 0.038.

CONCLUSIONS

This is the first study on myopia in Bhutan. As observed throughout East and Southeast Asia, the prevalence of myopia was higher in females and urbanites and positively associated with formal education. Given known risk factors, these prevalences may be driven by educational pressures and reduced time spent outdoors.