Advantages of the Utilization of Wide-Field OCT and Wide-Field OCT Angiography in Clinical Practice

Wide-field (WF) retinal imaging is becoming a standard diagnostic tool for diseases involving the peripheral retina. Technological progress elicited the advent of wide-field optical coherence tomography (WF-OCT) and WF-OCT angiography (WF-OCTA) examinations. This review presents the results of studies that analyzed the implementation of these procedures in clinical practice and refers to them as traditional and ultra-wide-field fluorescein angiography (UWF-FA). A PUBMED search was performed using the terms WF-OCT OR WF-OCTA OR UWF-FA AND the specific clinical entity, and another search for diabetic retinopathy (DR), retinal vein occlusion (RVO), Coats disease, peripheral retinal telangiectasia, peripheral retinal degeneration, lattice degeneration, and posterior vitreous detachment. The analysis only included the studies in which the analyzed field of view for the OCT or OCTA exam was larger than 55 degrees. The evaluation of the extracted studies indicates that WF imaging with OCT and OCTA provides substantial information on retinal disorders involving the peripheral retina. Vascular diseases, such as DR or RVO, can be reliably evaluated using WF-OCTA with results superior to standard-field fluorescein angiography. Nevertheless, UWF-FA provides a larger field of view and still has advantages over WF-OCTA concerning the evaluation of areas of non-perfusion and peripheral neovascularization. Detailed information on the vascular morphology of peripheral changes should be obtained via WF-OCTA and not angiographic examinations. WF-OCT can serve as a valuable tool for the detection and evaluation of vitreoretinal traction, posterior vitreous detachment, and peripheral retinal degeneration, and guide therapeutic decisions on a patient’s eligibility for surgical procedures.


Introduction
Optical coherence tomography (OCT) has become a standard method of retinal diagnostics for ophthalmologists.Since its commercial introduction at the beginning of this century, OCT has undergone many technological developments that have improved image resolution, artifact elimination, and the depth of scanning.Nevertheless, for many years, the horizontal dimensions of the scan were limited to 6 × 6 mm, that is, to the macular area.Over time, wider scans became possible, such as 12 × 12 mm.These scans covered the area of a classic fundus camera with a 55-degree field and were initially named wide-field OCT (WF-OCT) [1].The peripheral retina was still difficult to assess, especially when reaching outside the vascular arcades of the posterior pole; it required repositioning the fixation point and creating a mosaic of a few images [2].Such a montage provided a field of view between 70 and 80 degrees, as reported for the Plex®Elite 9000, (Carl Zeiss Meditec Inc., Dublin, CA, USA) device [3].Recent advancements in the optics used in OCT and an increase in the scanning speed have enabled wide-range scans of more than 20 mm in width.
For example, Xephilio OCT-S1 (Canon, Tokyo, Japan) which is based on a swept-source laser (SS-OCT), can capture a retinal area of 23 × 20 mm, which is approximately equivalent to an 80-degree viewing angle obtained in a single scan.The mosaic of 4-5 images enables the visualization of an area of 31 × 27 mm, thus reaching beyond the vortex veins.Some wide-filed OCT devices have the option of OCT angiography, which promises the reliable evaluation of the peripheral perfusion without the need to perform standard angiography, which requires the injection of dye.
A consensus on defining WF-OCTA was eventually reached by international experts (the Delphi approach).Wide-field OCTA was defined as capturing a field of view of at least 90 degrees [4].In practice, none of the commercially available OCT devices can obtain such a field of view with a single scan; it is only possible with a mosaic of wide-field images.Such a wide field of scanning is often called ultra-wide-field (UWF) in the medical literature.Sometimes, the term wide field is also used for OCTA scans of 12 × 12 mm.In this review, we analyzed studies that involved fields of view larger than 12 mm in width; in practice, this means areas larger than a 55-degree field of view.However, it must be noted that inconsistencies in the nomenclature of wide-field imaging are still present in the ophthalmological literature.As such, the present analysis of published studies was based on numbers (the dimensions of the scans) rather than the terms used in the studies.
The capabilities of wide-field OCT devices must be analyzed in reference to the color fundus and fluorescein angiography wide-field imaging (UWF-CP and UWF-FA).The International Widefield Imaging Group recommends using the term wide field for images that capture retinal areas posterior to the vortex vein ampulla in all four quadrants and ultra-wide-field for images that show retinal features anterior to the vortex vein ampullae [5].Such a recommendation sets the division point between WF and UWF imaging at approximately 100 degrees of field of view.Fundus cameras available on the market can capture significantly larger fields of view compared to OCT devices.For example, an Optos scanning laser ophthalmoscopy (SLO) camera provides standard images of 200 degrees with a single scan.The Zeiss Clarus 700 can obtain 133-degree images with a single scan and 200-degree images with a montage of two scans.
The present review aims to provide a descriptive and systematic analysis of the advantages of wide-field OCT and wide-field OCTA examinations compared to established angiographic imaging, such as standard FA or UWF-FA and UWF-CP.The review was performed for the specific clinical entities involving pathologies located at the peripheral retina.

Material and Methods
The database search was performed for clinical entities for which diagnostics of the peripheral retina are crucial for diagnosis and treatment.The search was performed using the following combination of terms: wide-field OCT OR wide-field OCT angiography OR wide-field fluorescein angiography AND the specific clinical entity.A separate search of the PUBMED database was performed for the following retinal disorders: diabetic retinopathy, retinal vein occlusion, Coats disease, peripheral retinal telangiectasia, peripheral retinal degeneration, lattice degeneration, posterior vitreous detachment, and retinal retinoschisis.The analysis only included the studies in which the analyzed field of view for the OCT or OCTA exam was larger than 55 degrees (areas larger than 12 × 12 mm) on either a single scan or a mosaic of scans.The results of the search are presented in the sections below, which are organized by disease.Rare disorders that were noted in the context of wide-field OCT examinations during the search were analyzed separately and are presented in a dedicated section below.

Diabetic Retinopathy
Diabetic retinopathy (DR) is a vascular disorder often associated with lesions located at the peripheral retina, which influence its classification, progression, and the development of diabetic macular edema.These issues were analyzed with UWF imaging: CP and FA.The use of UWF-FA enables a more precise classification of DR.Employing UWF-FA often makes the classification of DR more precise (for example, from non-proliferative to proliferative) as areas of neovascularization (NV) not detected with standard exams can be detected with UWF imaging [6][7][8][9].Moreover, the diagnosis of peripheral lesions in DR, especially peripheral areas of non-perfusion (NP), has a straightforward relationship with the risk of disease progression [10-12] and the incidence of diabetic macular edema (DME) [13].Additionally, defining areas of NP enables targeted retinal photocoagulation at the periphery, which requires a smaller area of retinal ablation compared to classic panretinal photocoagulation [14].In light of this knowledge, the visualization of peripheral vascular abnormalities by WF-OCTA, if comparably reliable to UWF-FA, may have a similar diagnostic value.Studies comparing WF-OCTA and UWF-FA in the context of diabetic retinopathy are summarized in Table 1.
The result analysis must take into consideration the following issues: differences in the obtained field of view, agreement between the examinations, sensitivity, and specificity in the detection of areas of NV.Most recent studies employed the newly introduced Xephilio OCT-S1 (Canon, Tokyo, Japan) WF-OCTA and compared the obtained scans to those taken using UWF-FA by Optos [16,17] or conventional FA [18].Comparisons with Optos, which provides a larger field of view than the Xephilio OCT S1, revealed high agreement between the exams in detecting the NVs in a small study by Bajka et al. [16]; however, a large study by Hamada et al. [17] proved the superiority of UWF-FA in detecting NVs due to the larger field of view and possible segmentation errors occurring with WF-OCTA.On the other hand, compared to standard FA, the Xephilio OCT S1 proved to be equally effective in detecting peripheral neovascularization [18].One recent study used the Zeiss Plex Elite WF-OCTA montage to determine the utility of the non-perfusion index (NPI) in diagnosing severe non-proliferative retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) [15].Although NPI was significantly higher for PDR compared to NPDR, its correlation with the proliferative status of retinopathy was diminished as some of the NVs were outside the range of the WF-OCTA exam.The study's conclusions are similar to those of Hamada et al.: detection of NV based on WF-OCTA is not as reliable as with UWF-FA due to the smaller field of view.
Older studies typically included only the Plex®Elite 9000, (Carl Zeiss Meditec Inc., Dublin, CA, USA) WF-OCTA with a mosaic of five images to obtain a large field of view [19][20][21][22][23][24].Comparisons with Optos [19,20,22-24] revealed a similar sensitivity in detecting NVs and NPs and its superiority over the standard FA when OCTA was equipped with a plus 20 D lens that significantly enlarged the field of view [21].Some authors reported high agreement between the UWF-FA and WF-OCTA devices in classifying DR [19].Discrepancies between the two examinations were noted in older studies in the interpretation of visualized vascular lesions.Pellegrini et al. [21] defended classic FA, stating that it provides more reliable data on the perfusion status of the retina; Russell et al. [22] and Zhang et al. [24] stated that OCTA provides more details of the observed neovascular changes.
The introduction of WF-OCTA increased the detection rate of vascular abnormalities in DR compared to standard OCTA [25].Both NP areas and the ischemic index were evaluated more precisely with 24 × 20 mm WF-OCT compared to 12 × 12 mm scans.In everyday practice, it must be remembered that the evaluation of the fundus cannot be omitted.The combination of WF-OCTA (prototype single capture at 65 degrees by Plex Elite) and UWF-CP can provide valuable information on retinal vasculature in DR [26].Example of WF-OCTA imaging with 24 × 20 mm scans is provided in Figure 1.For comparison, the UWF-FA image of proliferative DR is shown in Figure 2. The field of view is definitely wider for the UWF Optos system.20,[22][23][24] revealed a similar sensitivity in detecting NVs and NPs and its superiority over the standard FA when OCTA was equipped with a plus 20 D lens that significantly enlarged the field of view [21].Some authors reported high agreement between the UWF-FA and WF-OCTA devices in classifying DR [19].Discrepancies between the two examinations were noted in older studies in the interpretation of visualized vascular lesions.Pellegrini et al. [21] defended classic FA, stating that it provides more reliable data on the perfusion status of the retina; Russell et al. [22] and Zhang et al. [24] stated that OCTA provides more details of the observed neovascular changes.
The introduction of WF-OCTA increased the detection rate of vascular abnormalities in DR compared to standard OCTA [25].Both NP areas and the ischemic index were evaluated more precisely with 24 × 20 mm WF-OCT compared to 12 × 12 mm scans.In everyday practice, it must be remembered that the evaluation of the fundus cannot be omi ed.The combination of WF-OCTA (prototype single capture at 65 degrees by Plex Elite) and UWF-CP can provide valuable information on retinal vasculature in DR [26].Example of WF-OCTA imaging with 24 × 20 mm scans is provided in Figure 1.For comparison, the UWF-FA image of proliferative DR is shown in Figure 2. The field of view is definitely wider for the UWF Optos system.
(A)   WF-OCTA (24 × 20 mm) in DR can be used to quantify the vascular morphology at the peripheral retina in patients with DR [27].Alterations in angio-OCT parameters at the peripheral retina are noted in vascular density and the thickness of vascular capillary  WF-OCTA (24 × 20 mm) in DR can be used to quantify the vascular morphology at the peripheral retina in patients with DR [27].Alterations in angio-OCT parameters at the peripheral retina are noted in vascular density and the thickness of vascular capillary WF-OCTA (24 × 20 mm) in DR can be used to quantify the vascular morphology at the peripheral retina in patients with DR [27].Alterations in angio-OCT parameters at the peripheral retina are noted in vascular density and the thickness of vascular capillary complexes and can serve as predictors of DR development/progression.A similar approach can be employed with diabetic patients without developed retinopathy [28].An interesting utilization of WF-OCTA was presented in a case series by Wright et al. [29].The authors used this device to monitor PDR during pregnancy, when classic angiographic examinations are generally contraindicated.
The evaluation of the DR type can be enhanced not only by WF-OCTA but also by WF-OCT without the "angio" option [30].The authors used 14 × 9 mm fovea-centered scans with additional 6 × 6 mm scans oriented at the periphery (Silverstone, Optos).WF-OCT imaging, enhanced by additional peripheral scans, visualized the relationship between the suspected lesion and the retinal surface and posterior hyaloid, and determined the diagnosis of neovascularization instead of intraretinal microvascular abnormalities (IRMAs).The use of UWF-directed OCT enabled the detection of NV in an additional 25% of eyes, thus changing their classification to PDR.
As indicated by the above analysis, WF-OCTA is becoming a valuable tool for the examination of peripheral vascular changes in DR.Due to the large field of view and dye-independence, it has advantages over standard FA.Moreover, the lack of dye leakage enables a more precise evaluation of the vascular network at the periphery, especially in relation to the neovascularization of the RPE and posterior vitreous.Nevertheless, UWF-FA with the largest available field of view, 200 degrees, remains the most reliable tool for detecting vascular peripheral pathologies such as NVs and NPs.

Retinal Vein Occlusion
UWF-FA has been proven to be a valuable tool in imaging peripheral retinal areas in RVO [31].Its application resulted in the introduction of the ischemic index (ISI) formula, which expresses the relationship between non-perfused areas and the total retinal area imagined with WF scanning laser ophthalmoscopy [32][33][34][35].ISI is based on the pixel count and is calculated automatically by some software.Higher ISI values are associated with a higher risk of developing NV in BRVO; Tsui et al. suggested a cut-off value of 45% in this respect [36].The evaluation of UWF-FA and WF-OCTA showed high agreement between UWF-FA and standard OCTA in the evaluation of the extent of areas of non-perfusion.Existing studies on WF-OCTA in RVO are summarized in Table 2.The ischemic index on UWF-FA and the vascular density in the superficial and deep plexus correlated significantly (p = 0.019, r = 0.357 and p < 0.013, r = 0.375, respectively).The qualitative classification on wide-field OCTA and the ischemic index on UWF-FA correlated significantly (p < 0.001, r = 0.618).
For the detection of marked non-perfusion (ischemic index ≥ 25%), wide-field OCTA had a sensitivity of 100% and a specificity of 64.9%.Examples of WF-OCTA and WF-OCT imaging in RVO is provided in Figures 3 and 4. WF-OCTA enables the precise visualization of areas of non-perfusion at the peripheral retina and collateral vessels.For comparison, the UWF-FA image of RVO is provided in Figure 5.The visualized retinal area is wider for fluorescein angiography compared to OCTA.
A strong correlation between UWF-FA and WF-OCTA reflects the accurate detection of NP areas [37,39,41] and the ischemic index [38].It must be emphasized that, as with DR, the area of visualized NP is significantly larger in the case of UWF-FA exams [39,41].WF-OCTA is reportedly much more precise in detecting NVs compared to standard ophthalmoscopic examinations [40] or standard FA [42,43].OCTA provides details of the morphology of neovascularization that cannot be detected using angiographic tests [40].Such information is important in the context of the potential progression of NV and eligibility for pars plana vitrectomy (PPV).
Examples of WF-OCTA and WF-OCT imaging in RVO is provided in Figures 3 and  4. WF-OCTA enables the precise visualization of areas of non-perfusion at the peripheral retina and collateral vessels.For comparison, the UWF-FA image of RVO is provided in Figure 5.The visualized retinal area is wider for fluorescein angiography compared to OCTA.(A) (A)  A strong correlation between UWF-FA and WF-OCTA reflects the accurate detection of NP areas [37,39,41] and the ischemic index [38].It must be emphasized that, as with DR, the area of visualized NP is significantly larger in the case of UWF-FA exams [39,41].WF-OCTA is reportedly much more precise in detecting NVs compared to standard ophthalmoscopic examinations [40] or standard FA [42,43].OCTA provides details of the  A strong correlation between UWF-FA and WF-OCTA reflects the accurate detection of NP areas [37,39,41] and the ischemic index [38].It must be emphasized that, as with DR, the area of visualized NP is significantly larger in the case of UWF-FA exams [39,41].WF-OCTA is reportedly much more precise in detecting NVs compared to standard ophthalmoscopic examinations [40] or standard FA [42,43].OCTA provides details of the Besides WF-OCT and WF-OCTA exams, standard OCTA is often used to evaluate vascular alterations in RVO.Tang et al. measured the area of the periarterial capillary free zone (CFZ) and the ratio of CFZ to the artery area after anti-VEGF treatment [44].The study, based on 12 × 12 mm scans and performed with Plex®Elite 9000, (Carl Zeiss Meditec Inc., Dublin, CA, USA) revealed a significant decrease in areas of non-perfusion noted after treatment with intravitreal injections.OCTA also provides more detailed information on the development of collateral vessels, which are visualized with both a standard view and WF-OCTA [37].

Peripheral Retinal Degeneration
The search regarding peripheral retinal lesions and WF-OCT or WF-OCTA revealed four studies involving WF-OCT.
Govetto et al. retrospectively analyzed peripheral vitreoretinal interfaces with WF-OCT in cases with rhegmatogenous pathology [45].The authors reported interesting findings concerning the relationship between the presence of specific types of peripheral retinal degeneration and the vitreoretinal interface status.The retrospective analysis revealed 166 lesions present in the observed cases: 106 horseshoe tears, 22 operculated, 30 non-operculated holes (OHs), six giant tears, and two peripheral lamellar defects.The posterior vitreous detachment (PVD) was present in all eyes with tears and OHs but in fewer eyes with non-OH (26.3%), p < 0.001.Axial traction at the tears was evident at their anterior border (100%) but not the posterior one (17%), p < 0.001.OHs located posterior to the vitreous base were free from vitreous traction and presented with a morphology similar to macular holes.On the other hand, non-OHs were located anteriorly with signs of tangential traction in 76.7% of cases.Peripheral vitreoschisis was prevalent in non-OHs (83.3%) but not in horseshoe tears (16%), p < 0.001.Horseshoe tears and non-OHs were more often associated with retinal detachment, 54.7% and 50%, respectively, compared to OHs (22.7%), p = 0.023.All these data shed new light on the pathogenesis of rhegmatogenous lesions and their risk of progression to retinal detachment.With WF-OCT, such an evaluation is possible and might help choose the best therapeutic option (e.g., protective laser photocoagulation).Figure 6 provides a WF-OCT scan of an operculated retinal hole located at the periphery.
vascular alterations in RVO.Tang et al. measured the area of the periarterial capillary free zone (CFZ) and the ratio of CFZ to the artery area after anti-VEGF treatment [44].The study, based on 12 × 12 mm scans and performed with Plex® Elite 9000, (Carl Zeiss Meditec Inc., Dublin, CA, USA) revealed a significant decrease in areas of non-perfusion noted after treatment with intravitreal injections.OCTA also provides more detailed information on the development of collateral vessels, which are visualized with both a standard view and WF-OCTA [37].

Peripheral Retinal Degeneration
The search regarding peripheral retinal lesions and WF-OCT or WF-OCTA revealed four studies involving WF-OCT.
Gove o et al. retrospectively analyzed peripheral vitreoretinal interfaces with WF-OCT in cases with rhegmatogenous pathology [45].The authors reported interesting findings concerning the relationship between the presence of specific types of peripheral retinal degeneration and the vitreoretinal interface status.The retrospective analysis revealed 166 lesions present in the observed cases: 106 horseshoe tears, 22 operculated, 30 nonoperculated holes (OHs), six giant tears, and two peripheral lamellar defects.The posterior vitreous detachment (PVD) was present in all eyes with tears and OHs but in fewer eyes with non-OH (26.3%), p < 0.001.Axial traction at the tears was evident at their anterior border (100%) but not the posterior one (17%), p < 0.001.OHs located posterior to the vitreous base were free from vitreous traction and presented with a morphology similar to macular holes.On the other hand, non-OHs were located anteriorly with signs of tangential traction in 76.7% of cases.Peripheral vitreoschisis was prevalent in non-OHs (83.3%) but not in horseshoe tears (16%), p < 0.001.Horseshoe tears and non-OHs were more often associated with retinal detachment, 54.7% and 50%, respectively, compared to OHs (22.7%), p = 0.023.All these data shed new light on the pathogenesis of rhegmatogenous lesions and their risk of progression to retinal detachment.With WF-OCT, such an evaluation is possible and might help choose the best therapeutic option (e.g., protective laser photocoagulation).Figure 6 provides a WF-OCT scan of an operculated retinal hole located at the periphery.A similar topic was investigated by Kurobe et al. [46].The authors evaluated peripheral retinal degeneration and retinal detachment in 31 consecutive patients (37 eyes) using WF-OCT scans of 23 mm in width (Silverstone, Nikon Japan Healthcare, Tokyo, Japan).A similar topic was investigated by Kurobe et al. [46].The authors evaluated peripheral retinal degeneration and retinal detachment in 31 consecutive patients (37 eyes) using WF-OCT scans of 23 mm in width (Silverstone, Nikon Japan Healthcare, Tokyo, Japan).Lattice degeneration was found in eight eyes, paving stone degeneration in four eyes, unclassified in four eyes, retinal tears in twelve eyes (all horseshoe type), and retinal holes in nine eyes.The lesions were located at the mid-periphery (23 eyes) or far-periphery (14 eyes).Important findings were reported concerning the peripheral lesions.WF-OCT easily visualized the subretinal fluid, the detached edge of the degeneration, and vitreoretinal traction-factors that are important due to their potential progression.Rhegmatogenous retinal detachment was noted in 15 eyes, comprising one preoperative eye and 14 postoperative eyes.Vitreoretinal traction (VRT) was present in 10 of 27 eyes without a history of PPV.Similar imaging with WF-OCT scans of 23 mm in width was performed by Stanga et al. [47].Both Kurobe and Stanga emphasized the ease of the implementation and reliability of WF-OCT imaging for peripheral retinal disorders.The imaging of VRT with WF-OCT is provided in Figure 7.
eyes).Important findings were reported concerning the peripheral lesions.WF-OCT easily visualized the subretinal fluid, the detached edge of the degeneration, and vitreoretinal traction-factors that are important due to their potential progression.Rhegmatogenous retinal detachment was noted in 15 eyes, comprising one preoperative eye and 14 postoperative eyes.Vitreoretinal traction (VRT) was present in 10 of 27 eyes without a history of PPV.Similar imaging with WF-OCT scans of 23 mm in width was performed by Stanga et al. [47].Both Kurobe and Stanga emphasized the ease of the implementation and reliability of WF-OCT imaging for peripheral retinal disorders.The imaging of VRT with WF-OCT is provided in Figure 7.The presence and classification of PVD were evaluated with the use of WF-OCT (mosaic of images) by Tsukahara et al. [48].The authors included 144 healthy eyes of patients aged 29-95 years in the study.They proposed the classification of PVD into five stages: stage 0, without PVD (two eyes, both aged 21 years); stage 1, peripheral PVD limited to paramacular to peripheral zones (88 eyes, mean age 38.9 ± 16.2 years); stage 2, perifoveal PVD extending to the periphery (12 eyes, mean age 67.9 ± 8.4 years); stage 3, peripapillary PVD with persistent vitreopapillary adhesion alone (seven eyes, mean age 70.9 ± 11.9 years); and stage 4, complete PVD (35 eyes, mean age 75.1 ± 10.1 years).All stage 1 PVDs were observed in the paramacular to peripheral region.Progressing to stage 2 PVD, the area of PVD extended in two directions: posteriorly to the perifovea and anteriorly to the periphery.Vitreoschisis was observed in 41.2% of eyes at PVD initiation.These observations with WF-OCT provided novel and precise information on the location and progression of PVD.Such data would have been difficult to obtain with standard OCT (limited field of view) or ultrasound examination (lower resolution).An example of PVD imaging with WF-OCT is provided in Figure 8.The presence and classification of PVD were evaluated with the use of WF-OCT (mosaic of images) by Tsukahara et al. [48].The authors included 144 healthy eyes of patients aged 29-95 years in the study.They proposed the classification of PVD into five stages: stage 0, without PVD (two eyes, both aged 21 years); stage 1, peripheral PVD limited to paramacular to peripheral zones (88 eyes, mean age 38.9 ± 16.2 years); stage 2, perifoveal PVD extending to the periphery (12 eyes, mean age 67.9 ± 8.4 years); stage 3, peripapillary PVD with persistent vitreopapillary adhesion alone (seven eyes, mean age 70.9 ± 11.9 years); and stage 4, complete PVD (35 eyes, mean age 75.1 ± 10.1 years).All stage 1 PVDs were observed in the paramacular to peripheral region.Progressing to stage 2 PVD, the area of PVD extended in two directions: posteriorly to the perifovea and anteriorly to the periphery.Vitreoschisis was observed in 41.2% of eyes at PVD initiation.These observations with WF-OCT provided novel and precise information on the location and progression of PVD.Such data would have been difficult to obtain with standard OCT (limited field of view) or ultrasound examination (lower resolution).An example of PVD imaging with WF-OCT is provided in Figure 8.Despite the limited material on the diagnosis of peripheral retinal lesions with WF-OCT, this study's findings indicate that this diagnostic modality can play a crucial role in the follow-up of retinal degeneration and local conditions post-retinal surgery.The reliable detection of VRT and subretinal fluids with WF-OCT imaging can provide substantial information for the effective management of these disorders and decision making, especially concerning surgical procedures.

Other Clinical Entities
The use of WF-OCT enabled the determination of novel anatomic features of familial exudative vitreoretinopathy (FEVR).These included retinoschisis, focal retinal thickening, and the sudden thinning of the retina and retinal ridge.Additionally, UWF-SLO revealed a temporal mid-peripheral vitreoretinal interface abnormality (TEMPVIA), which was found in 88.3% of FEVR patients [49].In another study on FEVR, WF-OCTA had superior performance compared to UWF-SLO and comparable performance to UWF-FA in detecting peripheral vascular abnormalities, avascular zones, neovascularization, and TEMPVIA [50].
WF-OCTA was reported as a valuable imaging modality for retinal racemose hemangioma [51].Fluorescein angiography showed multiple lesions with intense leakage that obscured the view of the vessels.By contrast, WF-OCTA clearly presented the retinal capillaries of the hemangioma and adjacent retina.
WF imaging has the potential to diagnose ocular tumors located at the periphery.Attempts at such visualizations were made by McNabb et al. using a commercially available SS laser enhanced by additional indirect Volk lenses [52].The authors achieved more than twice the enlargement of the field of view compared with a standard OCT device.The prototype WF-OCT system enabled the visualization of 15 out of 16 tumors with a singlescan acquisition in the primary gaze.
Extended field imaging, including UWF-FA and WF-OCTA (Plex®Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA) with +20.0 D lens, was employed in the management of choroidal melanoma after radiation therapy [53].EFI OCTA provided a larger view of the areas compared to standard OCTA and a standard 55-degree fundus camera.The images showed a good definition of retinal and choroidal changes after radiotherapy, thereby enhancing the management of these patients.

Conclusions
Wide-field imaging with OCT and OCTA provides substantial information on retinal disorders involving the peripheral retina.Vascular diseases such as DR and RVO can be evaluated with WF-OCTA with results superior to standard fluorescein angiography.As long as convenience and reliability is considered, WF-OCTA imaging is on a good track to become an alternative to standard field-of-view FA imaging.
UWF-FA provides a significantly larger field of view compared to WF-OCTA and still has advantages regarding the evaluation of areas of NP and peripheral NV; however, detailed information on the vascular morphology of peripheral changes should be obtained via WF-OCTA and not angiographic examinations, which are characterized by dye leakage that obscures the view.It has to be remembered though that obtaining good-quality WF-OCTA images is laborious and typically requires many repetitions.Usually, such scans are burdened with artifacts that make precise analysis difficult, especially quantitative assessments.The improvement in scanning speed and elimination of artifacts by device software is required for WF-OCTA to become a widely used tool in clinical practice.
WF-OCT can serve as a valuable tool for the detection and evaluation of vitreoretinal traction, posterior vitreous detachment, and peripheral retinal degeneration, and guide therapeutic decisions concerning a patient's eligibility for surgical procedures.It facilitates information on the retinal-vitreous interface that can be sometimes hard to obtain by a simple fundus examination.Contrary to WF-OCTA, it is a fast test that can be easily utilized in a busy clinical practice.
And the end of this review, it can be stated that the reliability and subsequent wide use of WF-OCT and WF-OCTA examinations is strongly linked to technological progress, which continuously enables higher scanning speeds and larger fields of view.

Diagnostics 2024 ,
14, x FOR PEER REVIEW 6 of 18 the proliferative status of retinopathy was diminished as some of the NVs were outside the range of the WF-OCTA exam.The study's conclusions are similar to those of Hamada et al.: detection of NV based on WF-OCTA is not as reliable as with UWF-FA due to the smaller field of view.Older studies typically included only the Plex® Elite 9000, (Carl Zeiss Meditec Inc., Dublin, CA, USA) WF-OCTA with a mosaic of five images to obtain a large field of view [19-24].Comparisons with Optos [19,

Figure 1 .
Figure 1.(A,B).Proliferative diabetic retinopathy on WF-OCTA.(Xephilio OCT-S1 (Canon, Tokyo, Japan)).(A): The RPE-choroid scan shows the vascular network at the superficial capillary plexus (SCP) with large areas of hypoperfusion and NVE.The shadowing on the scan results from the presence of vitreous hemorrhage.(B): The internal limiting membrane (ILM) slab shows NVs protruding to the vitreous.

Figure 2 .
Figure 2. Imaging of proliferative diabetic retinopathy with UWF-FA (Optos ® 200Tx).Field of view provided with wide-field fluorescein angiography is considerably wider compared to Wf-OCTA from Figure 1.

Figure 1 .Figure 1 .
Figure 1.(A,B).Proliferative diabetic retinopathy on WF-OCTA.(Xephilio OCT-S1 (Canon, Tokyo, Japan)).(A): The RPE-choroid scan shows the vascular network at the superficial capillary plexus (SCP) with large areas of hypoperfusion and NVE.The shadowing on the scan results from the presence of vitreous hemorrhage.(B): The internal limiting membrane (ILM) slab shows NVs protruding to the vitreous.

Figure 2 .
Figure 2. Imaging of proliferative diabetic retinopathy with UWF-FA (Optos ® 200Tx).Field of view provided with wide-field fluorescein angiography is considerably wider compared to Wf-OCTA from Figure 1.

Figure 2 .
Figure 2. Imaging of proliferative diabetic retinopathy with UWF-FA (Optos ® 200Tx).Field of view provided with wide-field fluorescein angiography is considerably wider compared to Wf-OCTA from Figure 1.

Figure 5 .
Figure 5. Imaging of RVO with UWF-FA (Optos ® 200Tx).Areas of hypoperfusion are located in inferotemporal quadrant of the retina.The field of view is wider than provided with WF-OCTA.

Figure 4 .Figure 4 .
Figure 4. (A): The WF-OCT scan shows significant retinal thinning in the temporal part of the retina.(B): WF-OCTA shows large areas of hypoperfusion and arterio-venous anastomoses located in the inferotemporal sector of the retina (ischemic BRVO).Xephilio OCT-S1 (Canon, Tokyo, Japan).

Figure 5 .
Figure 5. Imaging of RVO with UWF-FA (Optos ® 200Tx).Areas of hypoperfusion are located in inferotemporal quadrant of the retina.The field of view is wider than provided with WF-OCTA.

Figure 5 .
Figure 5. Imaging of RVO with UWF-FA (Optos ® 200Tx).Areas of hypoperfusion are located in inferotemporal quadrant of the retina.The field of view is wider than provided with WF-OCTA.

Table 1 .
Comparison of studies on WF-OCTA versus wide-field and conventional fluorescein angiography in the context of diabetic retinopathy.Only the studies with a WF-OCTA field of view larger than 55 degrees were included.
® (field of 24 × 24 mm) 51 severe NPDR and PDR eyes, treatment-naïve; analysis of the utility of the non-perfusion index (NPI)The NPI was significantly higher in eyes with PDR (18.94% vs. 7.51%; p < 0.01).Measurement of NPI on the whole wide-field OCTA image was not sensitive enough to replace the detection of NV for the diagnosis of PDR.UWF-FA detected NV foci outside the range of WF-OCTA.

Table 2 .
Studies evaluating UWF-OCTA (visualization of at least 90 degrees) in the diagnostics of RVO.