The understanding of vitreomacular interface disorders has been considerably fostered by the development of high-resolution spectral-domain optical coherence tomography (SD-OCT).1 Such advances in macular imaging have facilitated both the study and the classification of each different clinical entity.
Although OCT-based diagnostic criteria for full-thickness macular hole (FTMH) and for non-FTMH have been fully described in literature, significant controversy still exists regarding their pathogenesis, management, and prognosis.1,2 Indeed, much morphological heterogeneity may be found while examining the different subtypes of macular holes, such as lamellar macular hole (LMH), and macular pseudohole (MPH). Moreover, the prognostic capacity and the ideal surgical timing remain two controversial aspects of the clinical management.1
It has been recently described that vitreoretinal traction can alter retinal vascular perfusion in a reversible fashion, suggesting that there can be a direct mechanical effect of vitreous traction on retinal vascular perfusion.3 Optical coherence tomography angiography (OCTA) is a novel noninvasive, dye-less method of retinal and choroidal microvasculature visualization that offers new insight into the retinal investigation.4 The microvascular changes that may occur along with the presentation of macular holes (MHs) have never been reported in the literature. Furthermore, these alterations might offer new perspectives in the pathophysiology of MH.
The purpose of the present study is to investigate, using OCTA, the microvascular modifications occurring in the different subtypes of MH, and to compare them with a control group.
Patients and Methods
In this observational, cross-sectional study, we used swept-source OCT (SS-OCT) and OCTA to compare the vascular density of the superficial capillary plexus (SCP), the deep capillary plexus (DCP), and the choriocapillaris (CC) among eyes with FTMH, LMH, and MPH. We also compared the foveal avascular zone (FAZ) area among the three groups. All the data obtained from investigational groups were compared with an age- and sex-matched control group and, if unaffected, with the fellow eye.
Thirty eyes of 30 subjects were consecutively recruited at the Vitreoretinal Surgery Service of the Ophthalmology Department, San Raffaele Scientific Institute, between November 2015 and February 2016. We certify that all applicable institutional and governmental regulations concerning the ethical use of human volunteers were followed during this study. The institutional review board of the San Raffaele Scientific Institute approved the research as an observational study, and all patients gave written informed consent to allow the utilization of their clinical data. The study was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki.
The inclusion criteria were diagnosis of idiopathic FTMH, LMH, or MPH (according to the International Vitreomacular Traction Study Group Classification),1 age of 18 years or older, and axial length of 24 mm ± 1 mm (measured with the IOLMaster [Carl Zeiss Meditec, Jena, Germany]).
Exclusion criteria for the study eye were a concurrent ocular disease other than macular hole involving the posterior segment (eg, uveitis, retinal vein occlusion, glaucoma, optic neuropathy), any previous posterior segment surgical or laser treatment, cataract surgery within the last 6 months, complicated cataract surgery, and any previous intravitreal injection of anti-vascular endothelial growth factor agents or corticosteroids. Eyes with optical media opacities that could interfere with a good quality imaging acquisition were excluded. Subjects with a history of arterial hypertension, diabetes mellitus, systemic vasculopathies (such as vasculitides), or connective tissue disease were also excluded from the study. Furthermore, we did not include eyes presenting with the clinical feature of epiretinal proliferation,5 as this aspect could have jeopardized the correct segmentation of the microvascular plexuses.
Patients underwent a complete ophthalmic examination, including best-corrected visual acuity (BCVA) on Early Treatment Diabetic Retinopathy Study charts, anterior segment biomicroscopy, applanation tonometry, indirect fundus exam, SS-OCT, and OCTA scans of the macula.
The fellow eye was examined in each subject, and was enrolled as control (“fellow unaffected”) in case of axial length of 24 mm ± 1 mm, adherence to the above-mentioned exclusion criteria, and absence of any vitreoretinal interface alteration (such as epiretinal membrane [ERM], MH, epiretinal proliferation, or vitreomacular traction).
A group of 10 healthy subjects was also included in the current analysis as control. Inclusion criteria were a silent ophthalmic pathological history, BCVA of 20/20 or better, axial length of 24 mm ± 1 mm, normal optic nerve with no neuroretinal rim alterations, anterior chamber with open angle, normal fundus biomicroscopy examination, SD-OCT scan within normal limits, no previous surgery other than uncomplicated cataract extraction, and intraocular lens (IOL) implantation.
SS-OCT and OCTA scans were obtained using the DRI OCT Triton (Topcon Corporation, Tokyo, Japan). Images were analyzed with the Topcon full-spectrum amplitude decorrelation angiography algorithm. This instrument has an A-scan rate of 100,000 scans/second, wavelength-scanning light centered at 1,050 nm and in-depth resolution of 2.6 mm (digital). Each OCTA contains 256 B-scans (each B-scan contains 256 A-scans). To image the motion of scattering particles (erythrocytes), four OCT raster scans are repeated at the same location (assisted by the eye-tracking). Aperture size was measured using the caliper function on SS-OCT. The minimum MH width was measured at the narrowest hole point in the mid-retina, using the OCT caliper function, as a line drawn parallel to the retinal pigment epithelium.1 Macular OCTA was acquired in the 3 mm × 3 mm macular area. One single experienced operator (LP) carried out all the examinations. Automated segmentation of SCP, DCP, and CC was performed. Manual adjustment of the segmentation was performed in cases of severe alteration of macular cytoarchitecture.
All 3 mm × 3 mm OCTA images were exported from the OCT database as a Joint Photographic Experts Group (JPEG) file and transferred into ImageJ version 1.48 software (National Institutes of Health, Bethesda, MD) for calculation purposes.
The FAZ area in the SCP was manually outlined through the polygon selection tool, and its area (in mm2) was calculated using a previously published method.6 The FAZ area was not recognizable in the DCP of FMTH, and it was not included in our analysis.
In order to calculate vessel density, images were binarized through a threshold strategy similarly to other studies.7,8 Specifically, an independent operator (AR) converted the image from 8-bit into red-green-blue (RGB) color type; split it into the three channels (red, green, and blue), choosing the red one as reference; applied a fixed threshold value, namely 80, to convert the image form a gray-scale one into a binary one; converted back the processed images to RGB; and restored the FAZ area and colors it with pure blue. Since in FTMH the FAZ area was not evaluable, the area corresponding to the wheel-like (see below) was erased and substituted with pure blue color. White pixels were considered as vessel, black pixels as background, and blue pixels were automatically excluded from the analysis. Vessel density was expressed as the ratio between measured vessel pixels and the total 3 mm × 3 mm area after subtracting FAZ area. SCP, DCP, and CC of subjects and healthy controls were analyzed using this method.
Variables included in the analysis were: age, sex, eye (right/left), BCVA, hole size (for FTMH), FAZ area in the SCP, and vessel density. All data are presented as mean ± standard deviation. All variables were tested for normal distribution using D'Agostino-Pearson test. Differences between groups for age, BCVA, FAZ area, and vessel density in every layer were assessed by means of one-way analysis of variance, and Bonferroni correction was used as post-hoc test. Differences between sex and qualitative analyses of OCTA scans were assessed by means of Chi-square test. Statistical analysis was performed with the GraphPad Prism software 6.0 (GraphPad Software, San Diego, CA). All tests were two-sided, and P values less than .05 were considered significant.
We analyzed 10 eyes affected by idiopathic FTMH, 10 with LMH, and 10 with MPH. The clinical features of the investigational groups and healthy controls are depicted in Table 1. All the continuous studied variables had a normal distribution. The average time from the MH diagnosis to the referral was 3.2 months ± 1.4 months.
Clinical Features of the Investigational Groups and Controls
We totally enrolled 17 (57%) fellow unaffected eyes, particularly five (50%) from the FTMH subgroup, five (50%) from the LMH subgroup, and seven (70%) from the MPH subgroup. All the remaining eyes were excluded because of the presence of a vitreoretinal interface disorder, particularly nine MPHs (53%), one vitreomacular traction (6%), three ERMs (18%), and four LMHs (23%).
The average MH size of the FTMH group was 518 μm ± 123 μm. BCVA turned out to be significantly different among the four groups (P < .0001), with a positive trend from FTMH (the lowest) to MPH (the highest). The post-hoc analysis revealed that such a result was driven by a significant difference among all the groups, except between MPH and controls, which did not show a significantly different distribution (P = .999).
The FAZ area in the SCP was similar in all the tested groups, as well as compared to controls and the fellow unaffected eyes (P = .435). Differently, the FAZ area in the DCP was not recognizable in any of the eyes with a FTMH and only in 30% of eyes with a LMH. In the FTMH cases, a wheel-like pattern was evident in place of FAZ at the DCP (Figure 1), where the wheel hub was represented by the hole edges and the spokes by the residual retinal tissue lining the cystic spaces at hole boundaries. The eyes with LMH, where the FAZ was not recognizable at the DCP, presented a nonspecific, irregular cystic pattern. The FAZ was always detectable in both MPH and controls, and their respective average area at DCP was similar (P = .101).
3 mm × 3 mm optical coherence tomography angiography scans of the macula of eyes affected by full-thickness macular hole (FTMH) (first column), lamellar macular hole (LMH) (second column), macular pseudohole (MPH) (third column), and a healthy eye (fourth column). The first line represents the superficial capillary plexus (SCP), the second line shows the deep capillary plexus (DCP), and the third line shows the choriocapillary (CC).
The vessel density was different among the investigational groups and controls both at the SCP and at the DCP (P < .0001 for both), whereas no significant difference was appreciated in the CC (P = .4100) (Table 2).
Macular Vessel Density and FAZ of the Superficial and Deep Capillary Plexuses and of Choriocapillaris in the Three Investigational Groups, Fellow Unaffected Eyes, and Controls
With regard to the SCP, the post-hoc analysis highlighted that the MPH vascular density was respectively lower than controls (P = .0165), LMH (P = .0046), and FTMH (P = .0005). The fellow unaffected eye group did not disclose statistically significant difference compared to the MPH group (P = .9999) and was respectively lower than controls (P = .0225), LMH (P = .0049), and FTMH (P = .0003) (Figure 2).
Boxer and whisker plots showing the foveal avascular zone (FAZ) area (A) and vascular density of the superficial capillary plexus (SCP) (B), deep capillary plexus (DCP) (C), and choriocapillary (CC) (D) among full-thickness macular hole (FTMH), lamellar macular hole (LMH), macular pseudohole (MPH), controls, and unaffected fellow eyes.
Concerning the DCP, the post-hoc analysis showed in the investigational groups a statistically significant decreasing trend of the vascular density from the FTMH to the MPH groups (P = .0092 for FTMH vs. LMH; P = .0011 for LMH vs. MPH; P = .0011 for FTMH vs. MPH). The FTMH disclosed also a higher vascular density compared to controls (P < .0001), whereas no difference was evident respectively between LMH and MPH compared to controls (Figure 2). The fellow unaffected eye group was inferior to FTMH (P < .0001) and to LMH (P = .0011). No difference was found between fellow unaffected eyes and MPH (P = .9999) and healthy controls (P = .3129).
It is known, by definition, that vitreomacular tractions are associated with intraretinal structural changes at the fovea.1 ERMs and vitreomacular tractions are reported to be associated also with retinal microvascular changes. Major vessels may become dilated and tortuous mostly because of the tangential traction applied by the membranes, resulting in macular edema and angiographic leakage.9 Furthermore, it has been recently described that vitreoretinal traction can alter retinal vascular perfusion in a reversible fashion, suggesting that there can be a direct mechanical effect of vitreous traction on retinal vascular perfusion.3
Considering the strong influence of the vitreoretinal interface also on MH formation,10 in our study we exclusively analyzed, using OCTA, the vascular changes occurring in the different subtypes of MH (FMTH, LMH, and MPH). Indeed, the anatomical modifications of idiopathic FTMH (including tractional foveal cystoid spaces, breakdown and elevation of central photoreceptors, and traction on the inner retina) are essentially triggered by a vitreous traction on the fovea from an anomalous posterior vitreous detachment. LMHs are thought to arise from an incomplete FTMH formation, ERM centripetal traction evolution, or both.1 Lastly, as ERMs are present in MPHs by definition, we may find in MPH much of the ERM characteristics, as the distortion of the foveal contour into a shape with a steep slope.1
So far, to the best of our knowledge, the alterations of the retinal vascular plexuses and of the choriocapillaris that may occur along with the presentation of a MH have never been reported in the literature.
The results of our study highlight the involvement of both the superficial (SCP) and the deep (DCP) retinal microvascular component in macular holes.
Interestingly, the MPH group revealed to have the lowest vascular density in the SCP compared to the other investigational groups and to controls. Since it has been described that ERM may directly induce various microvascular changes, some authors suggested that certain morphological abnormalities and circulatory disturbances in the perifoveal capillaries may occur from these retinal tractions.11 It may be hypothesized that the reduced vessel density, which we found in our results, may be due to the tangential tractional forces of the ERM, which is a characteristic feature of MPHs.
Conversely, in eyes with FTMH, the DCP seems to be the most involved capillary plexus. Indeed, this group showed the highest vascular density compared to controls and to all the other studied groups. It can be hypothesized that in eyes with newly diagnosed FTMH, a vascular engorgement is present, owing this process to the tangential tractional forces and the steepening of the MH edges. Being the DCP vascular density of LMHs was slightly superior (but not significantly different) compared to controls, we also hypothesize that LMH may present an early stage feature of a progressive vascular density increase.
These DCP changes raise further considerations. Significant changes of capillary blood flow velocity in the perifoveal areas were observed between normal subjects and eyes with ERMs. Indeed, a significantly slower blood flow velocity has been found in patients with ERM than that in healthy individuals.11 Furthermore, this velocity in the perifoveal capillaries has been shown to increase after surgical removal of ERM, assuming that vascular abnormalities may raise the venous resistance and reduce the capillary blood flow.12–14 Even though OCTA is not able to investigate the flow velocity, we speculate that the increased vessel density in the DCP may produce a rise of intraluminal pressure in the capillary bed, with consequent macular hypoperfusion. Moreover, since 10% to 15% of oxygen supplementation to photoreceptors derives from the DCP, a relative hypoperfusion at the DCP level may impact their integrity and function.15–17 This mechanism could explain part of the chronic progressive decay of vision that patients with FTMH experience throughout time, despite anatomical stability. Furthermore, a recent report described that in large longstanding FTMH, the DCP is rarefied compared to a newly diagnosed MH, owing this process to the subatrophy of the hole boundaries.18 These conclusions seem to corroborate our hypotheses.
It may be questioned as to whether the vascular changes are due to the development of holes, or if they predispose to the development of holes. In an attempt to answer this question, we also analyzed the fellow eyes, in case of absence of any vitreoretinal interface disorder. Our analysis showed that at the SCP, the fellow unaffected eyes had a vascular density similar to the MPH group, disclosing a reduced vascular density compared to FTMH, LMH, and even to healthy control eyes. On the contrary, the vascular density of fellow eyes, regarding the DCP, had the same characteristics of controls. This finding raises some additional considerations. The involvement of the SCP in the apparently unaffected fellow eyes of subjects with a MH may suggest an early contribution of the capillary plexus to the development of holes. It could be also hypothesized that these SCP changes of fellow unaffected eyes may be due, similarly to the changes we highlighted in MPHs, to the early influence of a very initial form of ERM (not visible at SD-OCT).
We may also assume whether the vascular density change in MH can be considered in the future as an early marker of prognosis and a useful indicator for surgery timing.
The FAZ area at the SCP level did not turn out to be significantly altered in the three investigational groups or in the control groups. The FAZ is known to be altered in ischemic retinopathies, being a primary sign of vascular damage.19,20 Our finding suggests that in MHs (and, more generally, in vitreoretinal interface disorder) the vascular alteration is a secondary disturbance more than a mere primary ischemic disorder.
We acknowledge that our study has several limitations, mainly due to the small sample size, the possible flaws of the software analysis, and the lack of FTMH staging. Furthermore, the study would have significantly benefited from a prospective design, with serial observation of retinal vascular changes throughout the follow-up after surgery. On the other hand, the strength of our study is the accurate eye selection, as we excluded patients with vascular comorbidities or longstanding macular holes, whose results could have jeopardized our research.
Despite these limitations, to the best of our knowledge this is the first study in the literature that selectively investigates the microvascular retinal vascular changes using OCTA in eyes with different types of MH. Thus, even though our conclusions are speculative, we believe our work open a new debate about the role of vascularization in MHs. Further aspects, especially by way of the investigation of postoperative changes after MH surgery, should be certainly considered for the correct pathophysiology interpretation and for a comprehensive analysis of this clinical aspect.
- Duker JS, Kaiser PK, Binder S, et al. The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology. 2013;120(12):2611–2619. doi:10.1016/j.ophtha.2013.07.042 [CrossRef]
- Govetto A, Dacquay Y, Farajzadeh M, et al. Lamellar macular hole: Two distinct clinical entities?Am J Ophthalmol. 2016;164: 99–109. doi:10.1016/j.ajo.2016.02.008 [CrossRef]
- Kashani AH, Zhang Y, Capone A Jr., et al. Impaired retinal perfusion resulting from vitreoretinal traction: A mechanism of retinal vascular insufficiency. Ophthalmic Surg Lasers Imaging Retina. 2016;47(3):1–11. doi:10.3928/23258160-20160229-03 [CrossRef]
- Rabiolo A, Carnevali A, Bandello F, Querques G. Optical coherence tomography angiography: Evolution or revolution?Expert Review of Ophthalmology. 2016;11(4):243–245. doi:10.1080/17469899.2016.1209409 [CrossRef]
- Lai TT, Chen SN, Yang CM. Epiretinal proliferation in lamellar macular holes and full-thickness macular holes: Clinical and surgical findings. Graefes Arch Clin Exp Ophthalmol. 2016;254(4):629–638. doi:10.1007/s00417-015-3133-9 [CrossRef]
- Samara WA, Say EA, Khoo CT, et al. Correlation of foveal avascular zone size with foveal morphology in normal eyes using optical coherence tomography angiography. Retina. 2015;35(11):2188–2195. doi:10.1097/IAE.0000000000000847 [CrossRef]
- Battaglia Parodi M, Cicinelli MV, Rabiolo A, Pierro L, Bolognesi G, Bandello F. Vascular abnormalities in patients with Stargardt disease assessed with optical coherence tomography angiography. Br J Ophthalmol. 2017;101(6):780–7856. doi:10.1136/bjophthalmol-2016-308869 [CrossRef]
- Battaglia Parodi M, Cicinelli MV, Rabiolo A, et al. Vessel density analysis in patients with retinitis pigmentosa by means of optical coherence tomography angiography. Br J Ophthalmol. 2017;101(4):428–432. doi:10.1136/bjophthalmol-2016-308925 [CrossRef]
- Maguire AM, Margherio RR, Dmuchowski C. Preoperative fluorescein angiographic features of surgically removed idiopathic epiretinal membranes. Retina. 1994;14(5):411–416. doi:10.1097/00006982-199414050-00004 [CrossRef]
- Stalmans P, Duker JS, Kaiser PK, et al. OCT-based interpretation of the vitreomacular interface and indications for pharmacologic vitreolysis. Retina. 2013;33(10):2003–2011. doi:10.1097/IAE.0b013e3182993ef8 [CrossRef]
- Kadonosono K, Itoh N, Nomura E, Ohno S. Perifoveal microcirculation in eyes with epiretinal membranes. Br J Ophthalmol.1999;83(12):1329–1331. doi:10.1136/bjo.83.12.1329 [CrossRef]
- Kadonosono K, Itoh N, Nomura E, Ohno S. Capillary blood flow velocity in patients with idiopathic epiretinal membranes. Retina. 1999;19(6):536–539. doi:10.1097/00006982-199911000-00010 [CrossRef]
- Yagi T, Sakata K, Funatsu H, Hori S. Evaluation of perifoveal capillary blood flow velocity before and after vitreous surgery for epiretinal membrane. Graefes Arch Clin Exp Ophthalmol. 2012;250(3):459–460. doi:10.1007/s00417-011-1618-8 [CrossRef]
- Yagi T, Sakata K, Funatsu H, Noma H, Yamamoto K, Hori S. Macular microcirculation in patients with epiretinal membrane before and after surgery. Graefes Arch Clin Exp Ophthalmol. 2012;250(6):931–934. doi:10.1007/s00417-011-1838-y [CrossRef]
- Birol G, Wang S, Budzynski E, Wangsa-Wirawan ND, Linsenmeier RA. Oxygen distribution and consumption in the macaque retina. Am J Physiol Heart Circ Physiol. 2007;293(3):H1696–1704. doi:10.1152/ajpheart.00221.2007 [CrossRef]
- Linsenmeier RA. Electrophysiological consequences of retinal hypoxia. Graefes Arch Clin Exp Ophthalmol. 1990;228(2):143–150. doi:10.1007/BF02764309 [CrossRef]
- Scarinci F, Jampol LM, Linsenmeier RA, Fawzi AA. Association of diabetic macular nonperfusion with outer retinal disruption on optical coherence tomography. JAMA Ophthalmol. 2015;133(9):1036–1044. doi:10.1001/jamaophthalmol.2015.2183 [CrossRef]
- Pierro L, Iuliano L, Bandello F. OCT Angiography features of a case of bilateral full-thickness macular hole at different stages. Ophthalmic Surg Lasers Imaging Retina. 2016;47(4):388–389. doi:10.3928/23258160-20160324-16 [CrossRef]
- Takase N, Nozaki M, Kato A, Ozeki H, Yoshida M, Ogura Y. Enlargement of foveal avascular zone in diabetic eyes evaluated by en face optical coherence tomography angiography. Retina. 2015;35(11):2377–2383. doi:10.1097/IAE.0000000000000849 [CrossRef]
- Wons J, Pfau M, Wirth MA, Freiberg FJ, Becker MD, Michels S. Optical coherence tomography angiography of the foveal avascular zone in retinal vein occlusion. Ophthalmologica. 2016;235(4):195–202. doi:10.1159/000445482 [CrossRef]
Clinical Features of the Investigational Groups and Controls
|Age (Years)||71.0 ± 11.0||66.4 ± 14.0||69.4 ± 7.7||60.8 ± 13.2||.304|
|BCVA (ETDRS Score)||41 ± 3||70 ± 5||82 ± 4||85 ± 0||< .0001|
Macular Vessel Density and FAZ of the Superficial and Deep Capillary Plexuses and of Choriocapillaris in the Three Investigational Groups, Fellow Unaffected Eyes, and Controls
|SCP||Vessel Density (%)||55.3 ± 7.2||51.1 ± 4.7||35.8 ± 6.7||37.3 ± 2.5||49.1 ± 9.7||< .0001|
|FAZ Area (mm)||0.26 ± 0.15||0.24 ± 0.13||0.29 ± 0.11||0.36 ± 0.18||0.31 ± 0.11||.4635|
|DCP||Vessel Density (%)||82.7 ± 16.8||63.7 ± 5.9||37.8 ± 2.5||41.8 ± 4.8||53.0 ± 12.2||< .0001|
|CC||Vessel Density (%)||69.6 ± 1.8||71.2 ± 2.1||68.5 ± 2.1||66.9 ± 4.9||70.1 ± 2.9||.4100|