Dr.Sabyasachi Bandyopadhyay, S12267,Dr. Samir Kumar Bandyopadhyay, Dr Mita Saha (DuttaChowdhury), Dr. Abhik Sinha
ABSTRACT
Purpose: To compare aqueous cytokine levels in diabetic macular edema (DME). Methods: Aqueous samples were obtained from 52 DME patients and 16 controls in this prospective study. Based on optical coherence tomography patterns 17 patients had diffuse retinal thickening (DRT), 20 patients had cystoid macular edema(CME) and 15 patients had serous retinal detachment(SRD). Interleukin (IL)-6, IL-8, vascular endothelial growth factor (VEGF) and tumor necrosis factor alpha (TNF- α) levels were measured by RayBio(R) Human ELISA Kit. Results: IL-6, IL-8 and VEGF levels differed significantly between three DME groups (p<0.001 in all cases) but the differences in TNF- α levels were not significant (p=0.226). VEGF and IL-6 levels correlated with central foveal thickness (CFT) in DRT and SRD groups respectively. Conclusion: Aqueous cytokine levels vary with different morphological patterns of DME.
Key words: Diabetic macular edema, cytokine, optical coherence tomography, central foveal thickness
Introduction
Diabetic retinopathy (DR) is the commonest complication of diabetes mellitus (DM) and affects one in three persons with DM.[1] Diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) are the main causes of vision loss. In DME, there is leakage of intraretinal fluid from abnormal retinal capillaries and micro aneurysms following a breakdown of the blood retinal barrier.[2] Studies have demonstrated that thickening of basement membranes, loss of pericytes, advanced glycation end product (AGE) deposition, changes in glial tissue and damage of the neurovascular unit are associated with the process of DME. [3] But, the molecular mechanisms that lead to DME remain incompletely understood. Vascular endothelial growth factor (VEGF) family, particularly the isoform VEGF-A is a potent mitogenic cytokine for vascular endothelial cells and has been demonstrated to be up regulated in hypoxic tissue. [4] In DR, loss of retinal capillaries causing hypoxia acts as a stimulus for increased retinal expression of VEGF-A [4]. Thus the role of VEGF may be central to DME pathogenesis. The efficacy of intravitreal anti-VEGF (e.g. ranibizumab) therapy in DME have been demonstrated by Ranibizumab for Edema of the mAcula in diabetes-2 (READ 2) and Ranibizumab in Diabetic Macular Edema Study (RESOLVE) . [5,6]
Other proposed mediators of DME include inflammatory cytokines, which are classic mediators of inflammation. The role of inflammation in the pathogenesis of DME is based on its known role in vasopermeability and substantiated by the efficacy of intravitreal steroid(e.g. triamcinolone acetonide) treatment of DME . [3] Like VEGF, inflammatory cytokines are soluble mediators so aqueous levels have been proposed for surrogate markers for retinal cytokines.
Interleukin 6 (IL-6) is a cytokine that induces acute phase reactions and increase vascular permeability. [7] Interleukin 8 (IL-8) is a pro-inflammatory and angiogenic cytokine produced by endothelial and glial cells in ischemic retina. [8] Different studies have demonstrated that IL-6 and IL-8 are related to the pathogenesis of DME . [9,10]
The tumor necrosis factor alpha (TNF- α) belongs to the group of pro-inflammatory cytokines and increased levels of TNF- α and TNF-receptors have been detected in serum of humans with uveitis . [11] But, there are differences in observations between investigators regarding the role of TNF-α in DME patients. Demircan et al have found increased levels of TNF- α in vitreous fluids of diabetic patients but Yoshimura et al and Suzuki et al did not observe such relationship. [12-14] DME was classified into three different patterns, such as, diffuse retinal thickening (DRT), cystoid macular edema (CME) and serous retinal detachment (SRD) based on optical coherence tomography (OCT) patterns of DME as reported by previous investigators . [15,16] To the best of our knowledge, there is only one previous study report of aqueous cytokine levels in these three patterns of DME (i.e. DRT, CME & SRD) . [17] The present study was carried out to compare the aqueous levels of various inflammatory and angiogenic cytokines (IL-6, IL-8, VEGF & TNF-α ) in three different morphologic patterns of DME and control subjects in Indian population.
Materials and methods
This prospective study was conducted in the ophthalmology department of a tertiary care hospital in Kolkata, eastern India between 1st July 2015 to 31st March 2016 for 9 months. Fifty two consecutive patients with DME aged above 18 years with no previous history of intraocular surgery or intravitreal injections were taken into study. Sixteen age matched healthy patients planned for cataract surgery without other ocular or systemic diseases were taken as controls.
The exclusion criteria included i) associated uveal or retinal pathology other than diabetic retinopathy, ii) glaucomatous eyes, iii) eyes with iris neovascularization, iv) laser photocoagulation within the past six months. The study was approved by the institutional review board and was performed in accordance with the declaration of Helsinki. A written informed consent was taken from each patient enrolled in this study. A complete ocular examination was done in all the cases including best corrected visual acuity (BCVA) testing, intraocular pressure(IOP) measurement and dilated fundus examination in slitlamp with +90D lens. Central foveal thickness (CFT) was measured as mean retinal thickness in a 1mm diameter zone centering the fovea with Spectral Domain OCT (RTVue-100, Optovue Inc., Fremont, CA) by MM6 protocol.
After dilating the pupils OCT measurements were done. Full thickness retinal measurements were performed within a 6mm diameter macular area (map diameters, fovea: 1mm, parafovea: 3mm, perifovea: 6mm) with 512×101 scan patterns (101 lines; 512 A-scans per line). DME was classified into three different patterns (i.e., DRT, CME & SRD). Sponge like retinal swelling of the macula with reduced intra retinal reflectivity was characterized by DRT (Fig. 1). CME group was characterized by intra retinal cystoid spaces with low reflectivity in the macular area separated by highly reflective septa (Fig. 2). SRD group had a shallow retinal elevation with optically clear space between sensory retina and the retinal pigment epithelium (Fig. 3). Patients having both DRT &CME were classified as CME group and patients having all three patterns (i.e., DRT, CME & SRD) were classified as SRD.
Aqueous samples (50-100 µl) were collected just before the intravitreal injection (Ranibizumab or triamcinolone acetonide) in the DME group and at the beginning of the cataract surgery in the control group. Aqueous humor was collected through a limbal paracentesis using a 30-gauze tuberculin syringe. The specimen was immediately transferred to a sterile plastic tube and kept at -700C until assayed. IL-6, IL-8, VEGF and TNF- α were measured in aqueous samples by RayBio(R) Human ELISA Kit (RayBiotech, Inc., Norcross, GA).
All data were tabulated in a Microsoft Excel 2007 spreadsheet. Results were recorded as the mean±SD or the median and range. The statistical analyses were performed using the program SPSS for Windows Version 17.0 (SPSS Inc., chicago, IL, USA.). The Pearson χ2 test was used to compare the proportions of qualitative variables. Student’s t-test was used to compare the means of the quantitative variables between two independent groups. The Kruskal-Wallis test (nonparametric analysis of variance) was performed to compare multiple groups. Spearman’s rank-order correlation coefficients were used to assess the relationship between cytokines and CFT. A p value less than 0.05 was considered statistically significant.
Results
A total of 52 consecutive diabetic patients fulfilling the criteria were enrolled (52 eyes; 28 males, 24 females) for the study. Sixteen eyes of 16 patients (7 males, 9 females) prepared for cataract surgery were taken as controls. Baseline patient characteristics were summarized in Table 1. Among 52 cases DRT was present in 17(32.69%) eyes, CME was present in 20(38.46%) eyes and SRD was present in 15 (28.85%) eyes. There were no significant differences between these three DME groups in relation to age (p= 0.285) and sex (p= 0.732). However, BCVA among these 3 groups were significant (p<0.001) with more deterioration of visual acuity in CME and SRD groups compared to DRT group.
Table 2 shows the aqueous concentrations of assayed angiogenic and inflammatory cytokines in three DME groups and control group. There were significant higher levels of IL-6 (p<0.0001), IL-8(p<0.0001), VEGF(p<0.0001) and TNF-α (p=0.0001) in the DME groups taken together compared with the control group.
The median aqueous humor concentration of IL-6 was 36.1 pg/ml (range:21.4 – 56.3pg/ml) in DRT group, 32.35 pg/ml (range:19.5 – 53.2pg/ml) in CME group and 56.1 pg/ml (range:26.3 – 86.3 pg/ml) in SRD group. The Box-and-whisker graph compares the aqueous IL-6 levels between 3 DME groups and the control group (Fig. 4). Among the three DME groups IL-6 levels were significantly different (p<0.001). IL-6 concentrations were significant between CME and SRD group (p<0.0001) or DRT and SRD group (p=0.0011) but not between DRT and CME group (p=0.1877).
The median aqueous humor concentration of IL-8 was 23.1 pg/ml (range:18.1 – 35.3pg/ml) in DRT group, 28.5 pg/ml (range:22.2 – 40.3pg/ml) in CME group and 35.5 pg/ml (range:23.5 – 59.6 pg/ml) in SRD group. The comparison graph of aqueous IL-8 levels between 3 DME groups and the control group is shown in Fig. 5. IL-8 concentrations were significantly different among three DME groups (p<0.001). IL-8 levels were also significant between DRT and CME group (p=0.002), CME and SRD group (p=0.0047) or DRT and SRD group (p=0.0001).
The median aqueous humor level of VEGF was 87.3 pg/ml (range:51.4 – 153pg/ml) in DRT group, 146.4 pg/ml (range:89.3 – 234.5pg/ml) in CME group and 196.5 pg/ml (range:139.2 – 324.4 pg/ml) in SRD group. Aqueous VEGF values between 3 DME groups and the control group were plotted as a graph in Fig. 6. VEGF concentrations were significantly different among three DME groups (p<0.001). VEGF levels were also significant between DRT and CME group (p<0.0001), CME and SRD group (p=0.0017) or DRT and SRD group (p<0.0001).
The median aqueous humor level of TNF-α was 210.4 pg/ml (range:154.2 – 286.4 pg/ml) in DRT group, 180.95 pg/ml (range:133.4 – 269.1pg/ml) in CME group and 196.3 pg/ml (range:143.2 – 263.2 pg/ml) in SRD group. The comparison graph of aqueous levels of TNF-α between 3 DME groups and the control group is shown in Fig. 7. TNF-α concentrations, however, were not significantly different among three DME groups (p=0.226). TNF-α levels also did not differ significantly between DRT and CME group (p=0.1098), CME and SRD group (p=0.3004) or DRT and SRD group (p=0.651).
The relationship between CFT and aqueous levels of cytokines were also analyzed in all the three DME groups. VEGF levels correlated positively with CFT in DRT group (p=0.0086) and IL-6 levels correlated positively with CFT in SRD group (p=0.012). But, IL-8 and TNF-α levels did not correlate significantly with CFT in any of the DRT, CME or SRD groups.
Discussion
Diabetic macular edema (DME) is a leading cause of visual loss in patients with diabetes and can occur at any stage of retinopathy. The molecular mediators involved in DME are not fully understood and it is not clear why in patients with similar severity of diabetic retinopathy some patients develop DME and others do not . [3,18] Previous studies have shown that VEGF plays an important role in increasing vascular permeability in diabetic eyes causing DME. [19-21] Increased vitreous and aqueous levels of other inflammatory cytokines like IL-1β, IL-6, IL-8, monocyte chemotactic protein (MCP)-1 are also related to DME . [9,10,18] Kim et al., recently compared the aqueous inflammatory and angiogenic cytokines in three different modalities of DME (i.e. DRT, CME and SRD) depending upon the OCT pattern, which is first of its kind to the best of our knowledge. [17] In our study we had additionally investigated the role of TNF- α along with other cytokines ( IL-6, IL-8 and VEGF ) in these three different varieties of DME in Indian perspectives.
DRT pattern in OCT indicates intracytoplasmic swelling of Muller cells due to ischemia which results in cytotoxic edema. [22,23] Cytotoxic edema in turn progresses to vasogenic edema which subsequently release vascular permeability substances like VEGF and other inflammatory cytokines from ischemic retina. [24,25] DRT progresses with liquefaction necrosis of Muller cells producing cystoid cavities and CME. So, CME denotes more severe form of diabetic macular edema than DRT. In SRD, there is deterioration of function of retinal pigment epithelium (RPE) by inflammation or ischemia which may cause accumulation of intra retinal fluid separating the sensory retina from RPE. [26]
In our study, aqueous IL-6 concentrations were significantly higher in SRD group compared to the DRT or CME group but there was no significant difference between DRT and CME group. This observation was similar to Kim et al who found significant higher aqueous IL-6 level in SRD group in comparison to CME group. [17] They however, did not observe any significant change between DRT and SRD group. Sonoda et al., also found significant association of IL-6 in vitreous fluid with SRD which supports the theory that inflammation plays an important role in the pathogenesis of SRD . [27]
Aqueous IL-8 concentrations were significantly different among three DME groups in our observation, highest level being recorded in SRD group followed by CME group. IL-8 levels were also significant between DRT and CME group, CME and SRD group or DRT and SRD group. Kim et al found similar results with higher values of IL-8 in SRD and CME group compared to DRT group. [17] Dong et al also recorded significantly higher aqueous IL-8 concentrations in diabetic patients with macular edema than diabetic patients without macular edema. [18] However, it was observed that increased IL-8 concentration in aqueous humor of patients with DME does not show a response to intravitreal steroid or anti-VEGF. [3] This necessitates the incorporation of other treatment modalities to reduce IL-8 function and anti-IL-8 antibody has been found to be effective in reducing endotoxin induced uveitis in rabbit model.[28]
We have observed significantly different aqueous VEGF concentrations among three DME groups as well as control and three DME groups. VEGF levels were highest in SRD group followed by CME and DRT group. This result was similar to Funatsu et al. who reported that aqueous VEGF concentrations was correlated with the severity of macular edema graded by morphological pattern. [29] Kim et al. also found significantly elevated aqueous humor concentration of VEGF in DME patients compared to controls. [17] They observed higher VEGF level in SRD group compared to CME and DRT group though the differences were not statistically significant. Dong et al also recorded significantly higher aqueous VEGF level in diabetic patients with macular edema compared to diabetic patients without macular edema. [18]
The cytokine TNF- α is produced by macrophages and T-cells and plays an important role in inflammation and apoptosis. [30] In vitreous fluids of diabetic patients increased levels of TNF- α have been found and a strong correlation between plasma levels of TNF- α and severity of DR has been reported. [12,31] However, Yoshimura et al and Suzuki et al did not observe an elevated concentration of TNF-α in vitreous samples from patients with diabetic macular edema. [13,14] In our study, the aqueous TNF-α concentration in DME group was significantly higher than the control group. But, TNF-α levels between three DME groups were not statistically significant. So, the role TNF-α of in DME needs to be further investigated. It may be possible that the choroid or retina themselves are the locus of increased TNF-α concentration, not the aqueous or vitreous body.
In our study, VEGF levels correlated positively with CFT in DRT group and IL-6 levels correlated positively with CFT in SRD group. But, IL-8 and TNF-α levels did not correlate significantly with CFT in any of the DRT, CME or SRD groups. Dong et al., have observed positive correlation of aqueous IL-6, IL-8 and VEGF concentrations with retinal macular thickness. [18] Kim et al., have found positive correlation of aqueous IL-6 and IL-8 level with CFT in CME group but none of the cytokines they studied (IL-6, IL-8, IP-10, MCP-1, PDGF-AA and VEGF) were positively correlated with DRT or SRD group. [17] The variability in the results between CFT and cytokine levels in different studies could be related to the variation in their sample sizes.
It has been reported by Kim et al that intravitreal injection of anti-VEGF bevacizumab was more effective in DRT pattern than CME or SRD which supported the theory that in CME and SRD along with VEGF other inflammatory cytokines are also involved in their pathogenesis so anti-VEGF treatment alone was not sufficient. [15] Similarly, Shimura et al showed that intravitreal triamcinolone acetonide to suppress prostaglandins and various cytokines had a better therapeutic effect than anti-VEGF treatment in patients with persistent diffuse DME. [32] There are evidences that complex interactions between VEGF and other cytokines rather than a single mechanism are involved in the pathogenesis of DME. VEGF can up regulate MCP-1 mRNA in cultured endothelial cells. [33] Furthermore, IL-6 can induce VEGF expression and promote angiogenesis. [7]
There are few limitations in our study. First, we have determined the aqueous samples rather than vitreous samples which could produce a more definitive reflection of retinal pathology. However, aqueous samples are easier and less risky to collect than vitreous samples. Second, the release of a particular cytokine can be a result of the disease process and not the cause of the disease. So, their role in pathogenesis cannot be definitely proved only by their detection in aqueous samples. Third, our sample size was small. Increasing the sample size will increase the statistical power to arrive at a definitive relationship between the variables under study.
In conclusion, our study indicates that a variety of angiogenic and inflammatory cytokines are found in increased concentrations in aqueous humor in three different morphologic patterns of DME though the role of TNF-α was not clearly established and both intravitreal steroid and anti-VEGF is necessary for comprehensive treatment in DME. Further study with larger sample size and more number of cytokines can lead to more definitive conclusions in future.
References
1..Yau JW, Rogers SL, Kawasaki R, Lamoureux EL, Kowalski JW, Bek T, et al. Global prevalence and major risk factors of diabetic retinopathy. Diabetes Care 2012; 35:556-64
2.Singh R, Ramasamy K, Abraham C, Gupta V, Gupta A. Diabetic retinopathy: An update. Indian J Ophthalmol 2008; 56:178-88
3.Owen LA, Hartnett ME . Soluble Mediators of Diabetic Macular Edema: The DiagnosticRole of Aqueous VEGF and Cytokine Levels in Diabetic Macular Edema. Curr Diab Rep 2013; 13: 476–480
4.Roberts WG, Palade GE. Increased microvascular permeability and endothelial fenestration induced by vascular endothelial growth factor. J Cell Sci 1995; 108:2369–2379
5.Nguyen QD, Shah SM, Khwaja AA, Channa R, Hatef E, Do DV et al. Two-year outcomes of the ranibizumab for edema of the macula in diabetes (READ-2) study. Ophthalmology 2010; 117:2146–2151
6.Massin P, Bandello F, Garweg JG, Hansen LL, Harding SP, Larsen M et al. Safety and efficacy of ranibizumab in diabetic macular edema (RESOLVE study): a 12-month, randomized, controlled, double-masked, multicenter phase II study. Diabetes Care 2010; 33:2399–2405
7.Funatsu H, Yamashita H, Ikeda T, Mimura T, Eguchi S, Hori S. Vitreous levels of interleukin-6 and vascular endothelial growth factor are related to diabetic macular edema. Ophthalmology 2003; 110(9):1690–1696
8.Yoshida A, Yoshida S, Khalil AK, Ishibashi T, Inomata H. Role of NF-kB-mediated interleukin-8 expression in intraocular neovascularization. Invest Ophthalmol Vis Sci 1998; 39:1097–106
9.Funatsu H, Noma H, Mimura T, Eguchi S, Hori S. Association of vitreous inflammatory factors with diabetic macular edema. Ophthalmology 2009; 116:73‑9
10.Roh MI, Kim HS, Song JH, Lim JB, Kwon OW. Effect of intravitreal bevacizumab injection on aqueous humor cytokine levels in clinically significant macular edema. Ophthalmology 2009; 116:80‑6
11.Rodrigues EB, Farah ME, Maia M, Penha FM, Regatieri C, Melo GB et al. Therapeutic monoclonal antibodies in ophthalmology. Prog Retin Eye Res 2009; 28:117-144
12.Demircan N, Safran BG, Soylu M, Ozcan AA, Sizmaz S. Determination of vitreous interleukin-1 (IL-1) and tumour necrosis factor (TNF) levels in proliferative diabetic retinopathy. Eye 2006; 20:1366–9
13.Yoshimura T, Sonoda KH, Sugahara M, Mochizuki Y, Enaida H, Oshima Y et al. Comprehensive analysis of inflammatory immune mediators in vitreoretinal diseases. PLoS ONE 2009; 4(12):e8158. doi:10.1371/journal.pone.0008158
14.Suzuki Y, Nakazawa M, Suzuki K, Yamazaki H, Miyagawa Y. Expression profiles of cytokines and chemokines in vitreous fluid in diabetic retinopathy and central retinal vein occlusion. Jpn J Ophthalmol 2011; 55:256-263
15.Kim M, Lee P, Kim Y, Yu SY, Kwak HW. Effect of intravitreal bevacizumab based on optical coherence tomography patterns of diabetic macular edema. Ophthalmologica 2011; 226:138-44
16.Shimura M, Yasuda K, Yasuda M, Nakazawa T. Visual outcome after intravitreal bevacizumab depends on the optical coherence tomographic patterns of patients with diffuse diabetic macular edema. Retina 2013 ;33:740-7
17.Kim M, Kim Y, Lee SJ . Comparison of aqueous concentrations of angiogenic and inflammatory cytokines based on optical coherence tomography patterns of diabetic macular edema. Indian J Ophthalmol 2015; 63:312-7
18.Dong N, Xu B, Chu L, Tang X. Study of 27 Aqueous Humor Cytokines in Type 2 Diabetic Patients with or without Macular Edema. PLoS ONE2015;10(4): e0125329. doi:10.1371/journal.pone.0125329
19.Selim KM, Sahan D, Muhittin T, Osman C, Mustafa O. Increased levels of vascular endothelial growth factor in the aqueous humor of patients with diabetic retinopathy. Indian J Ophthalmol 2010; 58:375‑9
20.Funk M, Schmidinger G, Maar N, Bolz M, Benesch T, Zlabinger GJ et al. Angiogenic and inflammatory markers in the intraocular fluid of eyes with diabetic macular edema and influence of therapy with bevacizumab. Retina 2010; 30:1412‑9
21.Funatsu H, Yamashita H, Nakamura S, Mimura T, Eguchi S, Noma H et al. Vitreous levels of pigment epithelium‑derived factor and vascular endothelial growth factor are related to diabetic macular edema. Ophthalmology 2006; 113:294‑301
22.Yanoff M, Fine BS, Brucker AJ, Eagle RC Jr . Pathology of human cystoid macular edema. Surv Ophthalmol 1984; 28 Suppl: 505‑11
23.Lee DH, Kim JT, Jung DW, Joe SG, Yoon YH. The relationship between foveal ischemia and spectral‑domain optical coherence tomography findings in ischemic diabetic macular edema. Invest Ophthalmol Vis Sci 2013; 54:1080‑5
24.Bringmann A, Uckermann O, Pannicke T, Iandiev I, Reichenbach A, Wiedemann P . Neuronal versus glial cell swelling in the ischaemic retina. Acta Ophthalmol Scand 2005; 83:528‑38
25.Coscas G, Cunha‑Vaz J, Soubrane G. Macular edema: Definition and basic concepts. Dev Ophthalmol 2010; 47:1‑9
26.Catier A, Tadayoni R, Paques M, Erginay A, Haouchine B, Gaudric A et al. Characterization of macular edema from various etiologies by optical coherence tomography. Am J Ophthalmol2005; 140:200‑6
27.Sonoda S, Sakamoto T, Yamashita T, Shirasawa M, Otsuka H, Sonoda Y. Retinal morphologic changes and concentrations of cytokines in eyes with diabetic macular edema. Retina 2014; 34:741‑8
28.Verma MJ, Mukaida N, Vollmer-Conna U, Matsushima K, Lloyd A, Wakefield D. Endotoxin induced uveitis is partially inhibited by anti-IL-8 antibody treatment. Invest Ophthalmol Vis Sci1999; 40(11):2465-2470
29.Funatsu H, Yamashita H, Noma H, Mimura T, Yamashita T, Hori S. Increased levels of vascular endothelial growth factor and interleukin‑6 in the aqueous humor of diabetics with macular edema. Am J Ophthalmol 2002; 133:70‑7
30.McDermott MF . TNF and TNFR biology in health and disease. Cell Mol Biol (Noisy-le-grand) 2001; 47:619-635
31.Doganay S, Evereklioglu C, Er H, Türköz Y, Sevinç A, Mehmet N et al . Comparison of serum NO, TNF-alpha, IL-1beta, sIL-2R, IL-6 and IL-8 levels with grades of retinopathy in patients with diabetes mellitus. Eye 2002; 16:163–70
32.Shimura M, Nakazawa T, Yasuda K, Shiono T, Iida T, Sakamoto T et al. Comparative therapy evaluation of intravitreal bevacizumab and triamcinolone acetonide on persistent diffuse.diabetic macular edema. Am J Ophthalmol 2008; 145:854‑61
33.Hong KH, Ryu J, Han KH. Monocyte chemoattractant protein-1- inducted angiogeneiss is mediated by vascular endothelial growth factor-A. Blood 2005; 105:1405-1407
Legends to figures:
Figure 1: Diffuse retinal thickening (DRT) pattern of diabetic macular edema (DME) showing sponge like retinal swelling of the macula with reduced intra retinal reflectivity on Optical coherence tomography (OCT)
Figure 2: Cystoid macular edema (CME) pattern of diabetic macular edema (DME) showing intra retinal cystoid spaces with low reflectivity in the macular area separated by highly reflective septa on Optical coherence tomography (OCT)
Figure 3: Serous retinal detachment (SRD) pattern of diabetic macular edema (DME) showing shallow retinal elevation with optically clear space between sensory retina and the retinal pigment epithelium on Optical coherence tomography (OCT)
Figure 4: Graph showing aqueous IL-6 levels between 3 DME groups and the control group
Figure 5: Graph showing aqueous IL-8 levels between 3 DME groups and the control group
Figure 6: Graph showing aqueous VEGF levels between 3 DME groups and the control group
Figure 7: Graph showing aqueous TNF-α levels between 3 DME groups and the control group
Legends to tables:
Table 1: Baseline characteristics of the control and three DME groups
Table 2: Aqueous concentrations (median value with range) of the angiogenic and inflammatory cytokines (pg/ml) in the control and three DME groups
| Table 1: Baseline characteristics of the control and three DME groups
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| Characteristics | Control group(n=16) | DME group | p value | ||||
| DRT group(n=17) | CME group(n=20) | SRD group(n=15) | Among 4 groups | Among 3 DMEgroups | |||
| Age (years) | 60.56±6.81 | 59.29±4.70 | 61.2±6.46 | 62.6±6.19 | 0.491 | 0.281
|
|
| Sex(Male/female) | 7/9 | 8/9 | 12/8 | 8/7 | 0.772 | 0.732
|
|
| BCVA(logMAR) | – | 0.54±0.15 | 0.71±0.14 | 0.78±0.11 | – | <0.001 | |
| Duration of diabetes(years) | – | 12.23±1.25 | 13.3±1.34 | 14.6±1.95 | – | <0.001 | |
| CFT(µm) | – | 385.29±27.12 | 494.95±34.55 | 569.33±29.08 | – | <0.001 | |
| Type of diabetes(type1/type2) | – | 5/12 | 4/16 | 5/10 | – | 0.652 | |
| Stage(NPDR/PDR) | – | 8/9 | 7/13 | 4/11 | – | 0.481 | |
| HbA1C (%) | – | 7.14±0.47 | 7.33±0.48 | 7.49±0.52 | – | 0.140 | |
| Insulin use(no/yes) | – | 10/7 | 14/6 | 9/6 | – | 0.739 | |
| Table 2: Aqueous concentrations (median value with range) of the angiogenic and inflammatory cytokines (pg/ml) in the control and three DME groups
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| Cytokine | Control group(n=16) | DME group | p value | ||||
| DRT group(n=17) | CME group(n=20) | SRD group(n=15) | Control vs DME | Control vs DRT vs CMEvs SRD | DRTvsCMEvs SRD
|
||
| IL-6 | 18.5(13.2-32.5) | 36.1(21.4-56.3) | 32.35(19.5-53.2) | 56.1(26.3-86.3) | <0.0001 | <0.001 | <0.001 |
| IL-8 | 13.85(10.2-21.2) | 23.1(18.1-35.3) | 28.5(22.2-40.3) | 35.5(23.5-59.6) | <0.0001 | <0.001 | <0.001 |
| VEGF | 49.7(28.5-86.3) | 87.3(51.4-153) | 146.4(89.3-234.5) | 196.5(139.2-324.4) | <0.0001 | 0.0017 | <0.0001 |
| TNF α | 159.25(190.1-107.4) | 210.4(154.2-286.4) | 180.95(133.4-269.1) | 196.3(143.2-263.2) | 0.0001 | <0.001 | 0.226 |