Foveal Avascular Zone In Patients Research Articles

Retinal capillary plexus in Parkinson's disease using optical coherence tomography angiography.

To evaluate the alterations of the retinal microvasculature and foveal avascular zone in patients with Parkinson's disease (PD) using optical coherence tomography angiography (OCT-A). A retrospective study of PD patients examined in the Ophthalmology Department of the General Hospital of Athens, "Georgios Gennimatas" from March 2021 to March 2022 was conducted. Totally 44 patients with PD were included and 18 healthy controls were examined, hence a total of 124 eyes were enrolled in the study. The foveal and parafoveal superficial and deep capillary plexus vascular density (fSCP-VD, fDCP-VD, pSCP-VD, pDCP-CD) and foveal avascular zone (FAZ) were quantified with OCTA. Optical coherence tomography (OCT) was used to measure macular thickness. Our statistical analysis was conducted by using a mixed effect linear regression model. After adjustment for age and gender, the mean parafoveal superficial capillary plexus vascular density (pSCP-VD) and mean parafoveal deep capillary plexus vascular density (pDCP-VD) were significantly decreased in individuals with PD (P<0.001 in both) by -2.35 (95%CI -3.3, -1.45) and -7.5 (95%CI -10.4, -4.6) respectively. fSCP-VD and fDCP-VD didn't approach statistical significance. The FAZ area and perimeter were significantly decreased (P<0.001 in both) by -0.1 mm2 (95%CI -0.13, -0.07) and -0.49 mm2 (95%CI -0.66, -0.32) respectively. Circularity didn't approach statistical significance. Central retinal thickness (CRT) was significantly decreased in individuals with PD (P<0.001) by -23.1 µm (95%CI -30.2, -16) and temporal retinal thickness (TRT) was decreased (P=0.025) by -11 µm (95%CI -22, -1.5) while nasal retinal thickness (NRT) only approached statistical significance (P=0.066). The mean pSCP-VD, pDCP-VD, CRT and TRT are significantly decreased and FAZ is altered in individuals with PD. These findings can be potentially used as biomarkers for the diagnosis and evaluation of early PD.

Analyses of Foveal Avascular Zone in Patients with General Blunt Ocular Trauma Using Optical Coherence Tomography Angiography.

To investigate the effect of blunt ocular trauma (BOT) on foveal circulation, and in particular the foveal avascular zone (FAZ), using optical coherence tomography angiography (OCTA). This retrospective study consisted of 96 eyes (48 traumatized eyes and 48 nontraumatized eyes) from 48 subjects with BOT. We analyzed the FAZ area of deep capillary plexus (DCP) and superficial capillary plexus (SCP) immediately after BOT and at 2 weeks after BOT. We also evaluated the FAZ area of DCP and SCP in patients with and without blowout fracture (BOF). There were no significant differences in FAZ area between traumatized and nontraumatized eyes at DCP and SCP in the initial test. In traumatized eyes, the FAZ area at SCP was significantly reduced on follow-up when compared to initial test (p = 0.01). In case of eyes with BOF, there was no significant differences in FAZ area between traumatized and nontraumatized eyes at DCP and SCP on initial test. No significant difference of FAZ area was found on follow-up relative to the initial test, whether in the DCP or SCP. In case of eyes without BOF, there was no significant differences of FAZ area between traumatized and nontraumatized eyes at DCP and SCP in initial test. Also, no significant difference of FAZ area at DCP was found on follow-up test compared to initial test. However, the FAZ area at SCP was significantly reduced in follow-up test compared with that in the initial test (p = 0.04). Temporary microvascular ischemia occurs in the SCP of patients after BOT. Patients should be warned of transient ischemic changes that may occur after trauma. OCTA can provide useful information regarding the subacute changes in the FAZ at SCP after BOT, even without evident findings of structural damage on fundus examination.

Value of the retina in the diagnosis of Alzheimer's disease

AbstractVision, which is a process that requires the involvement of a large number of neurons, is often impaired during Alzheimer's disease (AD). Over the past few decades, research has shown that several visual functions and structures are compromised during AD and can also be used to differentiate affected individuals from those who show normal aging. Retina is a projection from the central nervous system and shares many features with the brain. Classically, the damage in AD was thought to be restricted mainly to the brain. However, in the last years it has been demonstrated in retinas of AD human postmortem specimens, the presence of Aβ plaques and pTau deposition, being more abundant in the superior region of the retina matching with greater neuronal degeneration. Also, it has been suggested that Aβ plaques in the retina may anticipate those in the brain. In addition, recently it has also been possible to observe in vivo Aβ plaques in human retinas, with imaging techniques and ingesting curcumin as a marker of Aβ deposits. Recently, using in vivo hyperspectral imaging techniques in the retina, it has been reported that Aβ load in the brain can be predicted. These findings provide histopathological evidence that the visual system may be altered much earlier in the AD disease process than previously thought, and thus support the use of visual biomarkers in the early detection of the disease. Current in vivo imaging techniques such as OCT are allowing ophthalmologists to detect and quantify data consistent with the histopathological findings described in the retinas of AD patients. In early AD, OCT has demonstrated a thickening of the macular region and a subsequent thinning of the peripapillary area of the retina in more advanced stages of the disease. New analytic methods have shown in AD patients that thinned regions are interspersed with thickened ones in all retinal layers, except inner nuclear and outer segments. This causes roughness to appear on retinal layer thickness maps, finding that Fractal Dimension (FD) of retinal layers is greater in the AD patients, being roughness of retinal layers, assessed by the FD of their thickness maps, a possible early retinal biomarker of AD.In the other hand, recent data suggest the vascular involvement of the retina in AD patients. Vascular changes in the retina are thought to share similar pathogenic mechanisms with cerebral vasculature. OCT and OCT angiography (OCTA) has demonstrated a thinning of the choroidal thickness in early AD and decrease of the foveal avascular zone in patients with moderate AD.All these observations support the value of the retina as a biomarker of AD that will allow us, with the development of new research, to discover new retinal biomarkers that will help us to improve the diagnosis and follow‐up of this growing pathology.

Area of the foveal avascular zone in patients with refractive errors

To investigate the dependence of the area of the foveal avascular zone (FAZ) on axial eye length (AL) and to develop a feasible method for correcting this dependence. The study involved 209 patients over the age of 18 years (209 eyes), of them 52 patients with AL of 20-22 mm (hyperopia group), 60 patients with AL of 25.5-28.5 mm (myopia group) and 97 patients with AL of 22.5-24.5 mm (emmetropia group). Optical coherence tomography angiography (OCTA) examination was performed on Cirrus HD-OCT 5000 with AngioPlex («Carl Zeiss Meditec», Germany). FAZ area was corrected using the Littmann-Bennett formula modified by A.A. Shpak and M.V. Korobkova. FAZ area values both in emmetropic patients and in patients with refractive errors varied over a very wide range. Before correction, AL had a significant influence on the FAZ area (mm2), which compared to the emmetropia group (0.27±0.09) was significantly reduced in the myopia group (0.21±0.07; p<0.000) and increased in the hyperopia group (0.31±0.11; p=0.015). The corrected FAZ area values did not differ in the compared groups. After correction the FAZ area decreased on average by 19% in the hyperopia group and increased by 25% in the myopia group. A chart and an Excel (Microsoft)/LibreOffice Calc program have been developed for correction of the FAZ area depending on the AL. Refractive errors, especially high-degree ones, have a significant effect on the FAZ area. This study proposes an original chart and a calculation program for correct interpretation of FAZ area measurements in patients with refractive errors, providing an accessible and quick way to assess the obtained results.

Evaluation of macular microvasculature and foveal avascular zone in patients with retinal vein occlusion using optical coherence tomography angiography.

To quantitatively evaluate the vessel density of macular microvasculature, choriocapillary, and foveal avascular zone (FAZ) in both eyes of patients with unilateral retinal vein occlusion (RVO) using the optical coherence tomography angiography (OCTA) compared with the normal controls. A retrospective review was conducted on 72 patients with unilateral RVO (72 eyes with RVO and 72 RVO fellow eyes) and 72 healthy individuals (72 normal control eyes). The 3 × 3 mm macular angiogram was acquired using the OCTA. The vessel densities of the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillary plexus (CCP) were measured, and FAZ was quantified. The RVO eyes compared to their fellow eyes, and the fellow eyes compared to the normal controls, showed a significantly lower vessel density in both the SCP and DCP in the whole image and parafovea (P < 0.05) and the CCP (P < 0.05), except for the foveal region (P > 0.05). No significant differences between the RVO eyes and the fellow eyes in the FAZ area and perimeter (P > 0.05) were observed, while the acircularity index in the RVO eyes was significantly higher than the fellow eyes (P < 0.05). Additionally, the FD-300 in the RVO eyes was significantly lower than their fellow eyes (P < 0.05). The OCTA reveals that the macular microvasculature of the RVO fellow eyes can be impaired in both the superficial and deep retinal layer as well as the choriocapillary, suggesting the influence of systemic factors in the development of RVO.

Evaluation of retinal and optic nerve vasculature by optic coherence tomography angiography in Migraine with Aura

This study aimed to evaluate the retina by optic coherence tomography angiography (OCTA) in patients with migraine with aura (MA) in comparison with healthy controls. A total of 60 patients with MA and 56 control subjects who applied to the Ophthalmology Clinic of Dicle University between January 2020 and February 2020 were included in this study. In all patients, the vascular density (VD) of the radial peripapillary capillaries (RPCs) and optic nerve head (ONH), the VD of deep and superficial macular vascular networks, and foveal avascular zone (FAZ) were measured. Patients with MA showed reduced VD measurements of the nasal and inferotemporal ONH, inferonasal RPCs, and deep macular plexus. No statistically significant difference was observed in the superficial macular VD values between the study groups. The majority of patients with MA showed hypertrophy in the deep FAZ. There was a decrease in VD measurements in the deep macular capillary plexus, ONH, and peripapillary capillaries and hypertrophy in the deep FAZ in patients with MA. According to these results, patients with MA may have an increased risk of developing ocular and systemic vascular complications. Therefore, OCTA can be used to evaluate systemic and ocular hypoperfusion in patients with MA.

A Comparative Study of Macular and Choroidal Thickness and Blood-Flow Parameters in Patients with Intermediate and Simple Juvenile Moderate Myopia.

ObjectiveThis study aimed to compare the macular and choroidal thicknesses and blood-flow parameters of patients with intermediate and simple juvenile moderate myopia in order to provide a greater understanding of the pathogenesis of myopia and a basis for its prevention.MethodsParticipants were selected from patients under the age of 18 with moderate myopia who were treated in our ophthalmic clinic between June and December 2019. Seventy-five right eyes were selected from participants with a mean spherical equivalent ranging from −6.0 to −3.0 D. These samples were divided into two groups based on eye axial length (AL). The thicknesses of the macula and choroid, the area of the foveal avascular zone (FAZ), and the blood flow density of the macular capillaries were measured, intergroup comparison was conducted.ResultsThe average area of the FAZ was larger in the intermediate group than in the simple group. PERIM in the upper half was lower in the intermediate group than in the simple group, and the blood-flow density in the lower half of the macular area was higher in the simple group than in the intermediate group. The blood-flow density within 1 mm of the fovea centralis and the downward blood-flow density were higher in the intermediate group than in the simple group. The thicknesses of the lower part of the FAZ, the choroid of the fovea centralis, and the choroid under the retina were all larger in the intermediate group than in the simple group.ConclusionThe area of the FAZ in patients with intermediate juvenile moderate myopia is larger than that in patients with simple myopia; the choroid in the fovea of macula compensatorily increases, and blood flow density also increases; the thickness of the choroid under the retina increases with myopia.

Early microvascular changes in patients with prediabetes evaluated by optical coherence tomography angiography.

Background:Timely detection of early microvascular changes in patients with prediabetes could help reduce the likelihood of progression of diabetes-related retinal complications.Aim:To determine early microvascular changes in patients with prediabetes using optical coherence tomography angiography (OCT-A).Methods:In this single-center retrospective case-control study, macular OCT-A images of superficial capillary plexus (SCP) and deep capillary plexus (DCP) were analyzed in non-diabetic controls, and prediabetic and diabetic subjects. A quantitative analysis was performed using ImageJ software of the foveal avascular zone (FAZ) area, acircularity index (AI), perfusion density (PD), and vascular length density (VLD).Results:A total of 94 eyes of 53 patients were included in this study. The global mean age was 57.7 years, 39.6% men and 60.4% women. In SCP, the mean PD was 0.283 ± 0.15, 0.186 ± 0.720, and 0.186 ± 0.07 in non-diabetic controls, and prediabetic and diabetic groups, respectively. The mean VLD was 8.728 ± 3.425 in non-diabetic controls, 6.147 ± 1.399 in prediabetic group, and 6.292 ± 1.997 in patients with diabetes. The comparison of prediabetic patients and controls shows statistical differences between PD and VLD in both plexus SCP (p = 0.002 and p = 0.001, respectively) and DCP (p = 0.005 and p = 0.002, respectively). The mean area of FAZ in patients with diabetes and normal individuals was 0.281 and 0.196 mm2, respectively (p < 0.001). AI was higher in the control group (0.87 ± 0.14) and prediabetic group (0.80 ± 0.17) compared to diabetic patients (0.64 ± 0.19). There were no differences in FAZ area and AI between prediabetic and non-diabetic controls.Conclusion:PD and VLD demonstrated to be early microvascular changes in prediabetic patients evaluated by OCT-A. No alterations of FAZ were evidenced in this group.

Evaluation of The Foveal Avascular Zone Alterations Through Optical Coherence Tomography Angiography In Eyes With Retinal Vein Occlusion.

Background: To detect the effectiveness of OCT-A in evaluation of foveal avascular zone (FAZ) alterations in eyes with retinal vein occlusion . Objectives: To investigate the relationship between best-corrected visual acuity (BCVA) and the FAZ in patients with (RVO) evaluated with (OCT-A) in comparison to the unaffected fellow eyes. Patients and Methods: We retrospectively reviewed the medical records of 15 patients with (RVO); BRVO in 8 patients, CRVO in 7 patients) and we considered the unaffected fellow eyes of these patients as a control group, who were evaluated by OCT-A by a 6 mm × 6-mm region scan centered on the fovea and parafoveal area. The (FAZ), and foveal and parafoveal vascular density in superficial and deep vascular plexuses were analyzed. Result: The mean superficial FAZ area (SL FAZ area) measured 0.40mm in the study group and 0.30mm in the control group. The mean deep FAZ area(DL FAZ area) measured 0.46 mm in the study group and 0.35 mm in the control group. The SL FAZ and DL FAZ areas in eyes with RVO were larger than those in control eyes (P = 0.002, P = 0.033).We found a negative correlation between the BCVA and the superficial FAZ area in eyes with RVO (r = _0.42, P = 0.11).We found a negative correlation between the BCVA and deep FAZ area in the control group(r=_0.30, P 0.26). Conclusions: OCT-A allows detecting FAZ enlargement.Also, we found statistically significant negative correlation between FAZ enlargement and BCVA in patients with RVO.

Changes in the postoperative foveal avascular zone in patients with rhegmatogenous retinal detachment associated with choroidal detachment

Rhegmatogenous retinal detachment associated with choroidal detachment (RRDCD) refers to the detachment of the ciliary body and choroid from the sclera along with retinal detachment. The recovery of visual function is often far worse after surgical treatment of RRDCD than following anatomical reduction for complicated reasons. Some scholars have suggested that oxidative stress may cause serious damage to cells when the detached retina becomes reduced to the choroid-retinal pigment epithelium complex and consequentially has an abnormal blood supply, which may limit the recovery of vision after surgery. To observe changes in the blood flow in the macula in patients with RRDCD who underwent pars plana vitrectomy (PPV) for retinal reattachment and silicone oil filling. This retrospective, cohort-controlled study included 35 patients with RRDCD who underwent PPV for the first time and whose retinas were successfully reattached from January 2017 to May 2018. Another 36 patients with rhegmatogenous retinal detachment (RRD) who underwent PPV for the first time and had their retina reattached as well as 40 normal eyes were assessed as controls. The best corrected visual acuity (BCVAs; logMAR) and intraocular pressure were recorded at 1day, 1week, 1month, and 3months after the operation was recorded. Optical coherence tomography angiography was used to measure the area of the foveal avascular zone. At each time point after the operation, the area of the superficial plexus foveal avascular zone was not significantly different between the RRDCD and RRD groups. The area of the deep plexus foveal avascular zone (DFAZ) continued to enlarge after the operation in the RRDCD group but did not significantly change in the RRD group. A comparison of the two groups revealed that the DFAZ area was significantly larger in the RRDCD group than in the RRD group. The changes in DFAZ area in the RRDCD group were significantly different between 1day to 1month postoperatively (t = 0.054, P < 0.001), but there was no significant difference in the change from 1 to 3months postoperatively (t = 0.014, P = 0.063). The correlation between BCVA at 3months and DFAZ area one day after the operation in the RRDCD group was significant. Choroidal lesions in RRDCD patients may have an acute pathological effect on ischaemia of the deep retinal capillary network. The DFAZ area in RRDCD patients can be used to predict and evaluate postoperative visual acuity.

The evaluation of the early and intermediate age-related macular degeneration with optical coherence tomography angiography

Purpose: To investigate superficial and deep retinal vessels, foveal avascular zone in patients affected by age-related macular degeneration (AMD) to find whether any association between features on retinal vessel density and stage of AMD.Materials and Methods: Ninety-four patients enrolled in the study. Patients were divided according to AMD stages. Grade 1, no AMD; grade 2, early AMD; grade 3, intermediate AMD; grade 4 geographic atrophy (GA); and Grade 5, choroidal neovascularization (CNVM). All patients underwent an ophthalmologic evaluation, including optical coherence tomography angiography (OCTA). The main outcome measures were superficial vessel density, deep vessel density, foveal avascular zone (FAZ).Results: In grade 3 AMD eyes; the deep vessel density values were lower than grade 1 and grade 2 eyes. The fellow eyes of the patients with CNVM, the deep vessel density values were lower in grade 3 eyes than grade 1 and 2 eyes, the other parameters were not statistically different. The fellow eyes of the patients with grade 3, the vessel density, FAZ, AI did not show significant difference.Conclusion: Changes in retinal capillary vessel density, which can be detected with OCTA, begin at the intermediate stage AMD.

Phenotypic Spectrum of the Foveal Configuration and Foveal Avascular Zone in Patients With Alport Syndrome.

PurposeTo investigate characteristics of the foveal pit and the foveal avascular zone (FAZ) in patients with Alport syndrome (AS), a rare monogenetic disease due to mutations in genes encoding for collagen type IV.MethodsTwenty-eight eyes of nine patients with AS, and five autosomal-recessive carriers and 15 eyes from 15 age-similar healthy control subjects were examined using optical coherence tomography (OCT) and OCT-angiography (OCT-A). Foveal configuration and FAZ measures including the FAZ area, circularity, and vessel density in the central 1° and 3° were correlated.ResultsFoveal hypoplasia was found in 10 eyes from seven patients with either genotype. In contrast, a staircase foveopathy was found in seven eyes of four X-linked AS patients. The average FAZ area did not differ significantly between AS patients and control subjects (mean ± SD 0.24 ± 0.24 mm2 vs. 0.21 ± 0.09 mm2; P = 0.64). Five eyes showed absence or severe anomalies of the FAZ with crossing macular capillaries that was linked to the degree of foveal hypoplasia on OCT images leading to a significant inverse correlation of FAZ area and foveal thickness (r = −0.88; P < 0.001). In contrary, female patients with X-linked mutations exhibited a significantly greater FAZ area (0.48 ± 0.30 mm2 vs. 0.21 ± 0.09 mm2; P = 0.007), in line with OCT findings of a staircase foveopathy.ConclusionsThe foveal phenotypic spectrum in AS ranges from foveal hypoplasia and absence of a FAZ to staircase foveopathy with an enlarged FAZ. Because the development of the FAZ and foveal pit are closely related, these findings suggest an important role for collagen type IV in foveal development and maturation.

A Pilot Optical Coherence Tomography Angiography Study on Superficial and Deep Capillary Plexus Foveal Avascular Zone in Patients With Beta-Thalassemia Major

To investigate foveal avascular zone (FAZ) changes in the superficial (SCP) and deep (DCP) capillary plexuses in beta-thalassemia major (BTM) patients, as shown in optical coherence tomography angiography. Nonrandomized, comparative case series of 54 eyes of 27 BTM patients and 46 eyes of 23 healthy controls, utilizing an automated FAZ detection algorithm. Measurements included FAZ area and FAZ shape descriptors (convexity, circularity, and contour temperature). Results were compared between the two groups, and correlated to iron load and chelation therapy parameters. SCP and DCP FAZ area were not significantly different between the control and BTM groups (P = 0.778 and P = 0.408, respectively). The same was true regarding SCP FAZ convexity (P = 0.946), circularity (P = 0.838), and contour temperature (P = 0.907). In contrast, a statistically significant difference was detected between controls and BTM group regarding DCP FAZ convexity (P = 0.013), circularity (P = 0.010), and contour temperature (P = 0.014). Desferrioxamine dosage was strongly correlated to the DCP area (r = 0.650, P = 0.05) and liver magnetic resonance imaging/T2-star to DCP circularity (r = -0.492, P = 0.038). Correlations were also revealed between urine Fe excretion and DCP convexity (r = 0.531, P = 0.019), circularity (r = 0.661, P = 0.002), and contour temperature (r = -0.591, P = 0.008). Retinal capillary plexuses and especially DCP seem to present unique morphologic changes in BTM patients, not in the FAZ area, but in specific shape descriptors, indicating minor but detectable FAZ changes. These changes correlate well with iron load and chelation therapy parameters. Their clinical importance and pathophysiologic implications remain to be elucidated through further studies.

The retinal foveal avascular zone as a systemic biomarker to evaluate inflammatory bowel disease control

BackgroundInflammatory bowel disease (IBD) is a systemic inflammatory disease and is classified as Crohn’s disease (CD) or ulcerative colitis (UC) depending on the extent of gastrointestinal tract involvement. IBD can be associated with extraintestinal findings, such as fever, weight loss, arthralgia, and mucocutaneous lesions, as well as hepatic, renal and ophthalmological involvement. Clinical parameters and colonoscopy are used to establish the criteria for controlled or non-controlled disease and subsequent definition of treatment. Our objective in the present study was to compare the area of the foveal avascular zone (FAZ) in patients with a diagnosis of IBD during remission and active disease.Methods144 eyes of 72 patients with IBD were evaluated via a complete ophthalmological exam. Fundus photography and optical coherence tomography/angiography (OCT/OCTA) were performed with a Topcon Triton. The macula and posterior pole were evaluated by binocular indirect ophthalmoscopy and fundus biomicroscopy. The area of the FAZ was determined via manual delimitation of superficial retinal vascular layers from OCTA with image6.net software. To establish disease activity, we considered the Mayo Score, fecal calprotectin levels, colonoscopy results and clinical parameters. All retinal parameters were evaluated in a blinded manner. Means were compared between groups using the Mann–Whitney test.ResultsThe participants had a mean age of 42.26 years and included 28 males (38.88%) and 44 females (61.11%). Among the participants, 37 had a diagnosis of CD (51.38%), and 35 had a diagnosis of UC (48.61%). Twenty-five patients (34.72%) had active disease, and 47 (65.27%) were in remission. The area of the FAZ did not differ significantly between the CD and UC groups (p = 0.91 for the right eye and p = 0.76 for the left eye) but did differ significantly between the remission and active disease groups (p = 0.01 for the right eye and p = 0.02 for the left eye).DiscussionOur study is the first to evaluate the area of the FAZ in patients with IBD via swept-source OCTA. The area of the FAZ did not differ significantly in either eye between the CD and UC groups. However, patients classified as having active disease according to clinical parameters and colonoscopy presented a significant decrease in the area of the FAZ compared with patients in remission. The area of the FAZ is an ophthalmological parameter that can be obtained non-invasively and is increased in ischemic diseases such as diabetic retinopathy. The FAZ may decrease due to vascular engorgement or increased systemic inflammation. This parameter can be used to help determine whether a patient is in remission or active IBD, thus potentially reducing the need for invasive exams during disease follow-up.

Optical coherence tomography angiography and microvascular changes in diabetic retinopathy: a systematic review.

To use optical coherence tomography angiography (OCTA) to evaluate foveal microvascular changes in diabetes by comparing the area of foveal avascular zone (FAZ) in healthy controls and patients with diabetes with no diabetic retinopathy (NDR) as well as different stages of diabetic retinopathy (DR). A systematic literature search was performed based on the population, intervention, comparison and outcome (PICO) strategy by two independent reviewers. The search was performed in PubMed, Embase and Cochrane Library, including keywords 'diabetes mellitus', 'DR' and 'OCTA'. Of 358 studies initially identified, 215 studies were screened after duplicate removal. Of these, we included 12 (nine cross-sectional and three retrospective) studies in this review. With the data at hand, it was not possible to perform a meta-analysis. The selected studies included patients with NDR (n=8), non-proliferative diabetic retinopathy (NPDR, n=8) and proliferative diabetic retinopathy (PDR, n=6). Several of the studies provided information for more than one diabetic group. In general, there was a trend towards a larger area of FAZ in patients with diabetes. As compared to healthy controls, this was reported in patients with NDR (five of eight studies), NPDR (seven of eight studies) and PDR (six of six studies). Optical coherence tomography angiography (OCTA) is non-invasively able to identify foveal capillary non-perfusion as an early event in DR. In some studies, this has even been identified in patients without clinically identifiable microvascular lesions. Longitudinal studies would be needed to examine if OCTA-findings are able to predict long-term structural and functional outcome.

Quantitative Assessment of Foveal Avascular Zone in Patients with Early and Intermediate Nonexudative Age-Related Macular Degeneration Using Optical Coherence Tomography-Angiography

Optical coherence tomography-angiography (OCT-A) is a relatively new non-invasive imaging technique which provides three-dimensional visualization of the retinal and choroidal microvasculature. Recently, OCT-A is widely used in the diagnosis of age-related macular degeneration (AMD). Purpose: To compare 3 quantitative indexes of foveal avascular zone (FAZ)—area (A), perimeter (Pm), and circularity (C) in patients with early and intermediate nonexudative AMD and healthy subjects using OCT-A. Methods: Eighty-nine patients with nonexudative AMD (n = 89 eyes) were enrolled in the study. They were compared with sex- and age-matched control group of 66 healthy subjects (n = 66 eyes). The patients with nonexudative AMD were divided into 2 subgroups—early AMD (n = 42 eyes) and intermediate AMD (n = 47 eyes). All participants underwent OCT-A (3 × 3 mm scans, Cirrus HD-OCT, Angioplex, Carl Zeiss Meditec, Dublin, CA). Results: There was no statistically significant difference in all 3 assessed indexes between the early AMD subgroup and the control group (A ? P = 0.139; Pm ? P = 0.230; and C ? P = 0.191). There was also no statistically significant difference in all 3 assessed indexes between the intermediate AMD subgroup and the control group (A ? P = 0.106, Pm ? P = 0.124, and C ? P = 0.102, respectively). Conclusions: According to our results from the assessment of FAZ in patients with early and intermediate AMD, we hypothesize that macular perfusion remains fairly unchanged in the nonexudative stages of the disease. OCT-A is a reliable technique for visualizing and quantifying FAZ in patients with nonexudative AMD.

Optical Coherence Tomography Angiography in Central Retinal Vein Occlusion: Correlation Between the Foveal Avascular Zone and Visual Acuity.

To investigate the relationship between best-corrected visual acuity (BCVA) and the foveal avascular zone (FAZ) in patients with central retinal vein occlusion (CRVO) evaluated with optical coherence angiography (OCT-A). The study was a prospective consecutive case series including 24 patients with CRVO. All patients received either aflibercept or ranibizumab intravitreal injections prior to analysis. Best-corrected visual acuity and FAZ were evaluated in eyes without macular edema. The FAZ areas were evaluated with OCT-A in both the superficial and deep capillary plexus layers by using 3 × 3-mm images of the macula. Disruption of the ellipsoid zone (EZ) was also analyzed. The mean superficial FAZ area measured 0.76 mm2 (95% confidence interval [CI] 0.50-1.13). The mean deep FAZ area measured 1.12 mm2 (95% CI 0.77-1.47). In a multivariable analysis a negative correlation was found between the BCVA and the superficial FAZ area (r = -0.54, P = 0.03). The correlation between the BCVA and deep FAZ area did not meet statistical significance (r = -0.43, P = 0.09). In a multivariable analysis, disruption of the ellipsoid zone was significantly correlated to a larger superficial FAZ area (r = 0.68, P = <0.001) and poor visual acuity (r = 0.75, P < 0.001). Optical coherence tomography-A is a novel technique that allows segmented evaluation of the FAZ in patients with CRVO providing additional prognostic information. The FAZ areas were enlarged both in the superficial and the deep capillary networks. A significant correlation was found between BCVA and the FAZ area in CRVO patients without macular edema (ClinicalTrials.gov, number NCT02274259).

Krypton Laser Photocoagulation for Neovascular Lesions of Age-Related Macular Degeneration

To the Editor. —The Macular Photocoagulation Study (MPS) Group recently reported the results of a randomized clinical trial comparing krypton red laser photocoagulation with no treatment for choroidal neovascular lesions involving the foveal avascular zone in patients with age-related macular degeneration. 1 Although a thorough review of the literature was not the purpose of the report, earlier work by Yassur et al 2 had bearing on the MPS results and should have been cited. Their results from a randomized trial involving 123 eyes with age-related macular degeneration and neovascular lesions involving the foveal avascular zone showed that 37 (67% ) of 55 untreated eyes had deterioration in visual acuity in comparison with only 22 (32% ) of 68 eyes treated with krypton laser. The MPS results for similar eyes showed that 98 (58% ) of 169 untreated eyes in comparison with 86 (49% ) of 174 treated eyes had severe visual loss (six or