Molecular Changes in Aqueous Humor Associated with Inflammation Following Cataract Surgery in Patients with Fuchs’ Endothelial Corneal Dystrophy

Abstract

Introduction

To evaluate the anterior chamber (AC) inflammation in the early postoperative period after cataract surgery and before Descemet membrane endothelial keratoplasty (DMEK) by quantifying oxidative stress and inflammatory mediators in aqueous humor of patients with Fuchs’ endothelial corneal dystrophy (FECD).

Methods

In this prospective single-center study, 15 patients with FECD underwent cataract surgery and DMEK in a two-stage procedure. Aqueous humor was collected from the AC at the beginning of cataract surgery and 3 months later at the beginning of DMEK. In the control group, which consisted of 15 age-matched phakic patients without FECD, aqueous humor was only collected at the beginning of cataract surgery. Mediators of postoperative inflammation including TNF-α, VEGF, IL-2, IL-1 β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, GM-CSF, IFN-γ, CXCL5/ENA-78, FGF-basic, G-CSF, IL-1-α, IL-1-ra, IL-17, CCL2/MCP-1, CCL3/MIP-1a, CCL4/MIP-1b, TPO, TGF-β-1, TGF-β-2, and TGF-β-3 concentrations were measured using a Multiplex-Array-System.

Results

The concentration of TNF-α (p = 0.021), IL-6 (p = 0.005), IL-8 (p = 0.001), CXCL5/ENA78 (p = 0.002), CCL2/MCP-1 (p = 0.001) and CCL4/MIP-1b (p = 0.037) were significantly higher 3 months after cataract surgery at the beginning of DMEK compared to control group at beginning of cataract surgery. The levels of IL-2, IL-5, IL-8, IL-10, and IL-1-α were significantly higher in phakic eyes in the control group (p < 0.05) before cataract surgery.

Conclusions

The present study indicates significantly increased proinflammatory cytokines 3 months after cataract surgery in eyes with FECD. Our findings suggest postoperative inflammation in the AC up to 3 months after cataract surgery. Therefore, it may be reasonable to combine cataract surgery with DMEK in cataract patients with FECD.

Key Summary Points

Why carry out this study?

This study investigated the inflammatory response following cataract surgery in patients with Fuchs’ endothelial corneal dystrophy (FECD), a condition that complicates surgical outcomes.

The study aimed to provide recommendations for the optimal timing of Descemet membrane endothelial keratoplasty (DMEK) surgery in patients with FECD.

What was learned from the study?

The study found that alterations in proinflammatory cytokines might be the underlying cause of persistent anterior chamber (AC) inflammation after cataract surgery.

These findings suggest that either combining cataract surgery with DMEK in phakic FECD patients or extending the interval between the two procedures may offer greater benefits by potentially enhancing patient outcomes and minimizing postoperative inflammation.

Introduction

Fuchs’ endothelial corneal dystrophy (FECD) is a disorder of the corneal endothelium that typically appears bilaterally in Caucasian middle-aged women [1]. According to current estimates, approximately 300 million individuals aged 30 years and above worldwide are reportedly affected by FECD [2]. While often sporadic, it has also been associated with an autosomal dominant trait [3, 4]. The endothelial cell dysfunction is considered as the primary cause of the disease [5]. Specifically, FECD involves progressive loss of endothelial cells, which results in blurred vision and glare that ultimately cause visual impairment.

Currently, endothelial keratoplasty such as Descemet membrane endothelial keratoplasty (DMEK) is considered the gold standard for the treatment of FECD [6, 7]. This surgical technique has significantly improved the outcomes and has reduced the risks of graft rejection or failure [7].

In elderly patients, endothelial dysfunction is often accompanied by increasing age-related lens opacity. In such cases, cataract surgery can be performed before, simultaneously, or after DMEK. Cataract surgery without DMEK may be an option for cataract patients with mild FECD and no signs of clinical or tomographic corneal edema [7–9]. DMEK without cataract surgery may be reasonable in young patients with clear lenses who still have the ability to accommodate. The combined approach (so-called “triple-DMEK”) avoids a second surgical procedure and endothelial cell loss due to a second surgery [10]. Some studies indicate that the accuracy of IOL calculations in triple-DMEK is affected by the corneal changes induced by the procedure. These changes can make the calculations less predictable, leading to residual refractive errors post-surgery [11]. Additionally, there is consistent reporting of higher rebubbling rates in triple-DMEK cases, with some studies showing significant associations between rebubbling and graft failure [12].

However, other research suggests that the difference in complications and outcomes between triple-DMEK and the two-stage procedure may not be as pronounced. Some studies show no significant differences in long-term outcomes such as visual acuity, despite the initially higher rebubbling rates [13, 14].

While cataract surgery is one of the most common and safest surgeries worldwide [15], postoperative inflammation remains a challenging clinical problem. Studies suggested that inflammation triggered in lens epithelial cells (LECs) after cataract surgery can be a major cause of posterior capsule opacification [16]. Furthermore, it is discussed that an inflammatory reaction triggered by exposed LECs can cause changes in the surrounding eye tissues, affecting the development of neurodegenerative retinal diseases such as open-angle glaucoma [17]. Similarly, there is a growing body of evidence that suggests such inflammatory reactions can be exacerbated by pre-existing eye conditions and inflammatory states [18–21].

It is not surprising that factors such as heat shock, oxidative stress, mechanical stress, and activation of tissue repair programs are associated with changes in the expression of various proteins and composition of the aqueous humor [22–24]. However, it remains unclear to which extent the postoperative inflammation after cataract surgery may influence graft survival after DMEK in patients with FECD. Thus, we aimed to investigate the inflammatory response after cataract surgery in patients with FECD to give a recommendation for timing of DMEK surgery in these patients.

Methods

Patients

In this single-center, prospective, interventional study, 15 phakic patients with FECD underwent cataract surgery and DMEK in a two-step procedure within 3 months (FECD group). Fifteen phakic patients without ophthalmological pathologies underwent cataract surgery and served as a control group. In total, 30 patients with an average age of 69.1 ± 8.9 years (range 52–86 years) were analyzed. Among them, 60% (18 patients) were male (Table 1). Patients with previous intraocular surgery, uveitis, vasculitis, proliferative vitreoretinopathy, or neovascular age-related macular degeneration were not recruited in the study.

Table 1.

Demographical characteristics

Parameter	FECD group	Control group
N, eyes	15	15
Sex, male (%)	8 (53)	10 (67)
Age (SD), years	69.3 (6.7)	70.1 (10.1)

FECD Fuchs endothelial corneal dystrophy

In the FECD group, the preoperative best-corrected visual acuity (BCVA) was 0.34 ± 0.10 in logarithm of the minimum angle of resolution (logMAR), which improved to 0.14 ± 0.09 logMAR following DMEK. The central corneal thickness (CCT) decreased from 609.60 ± 64.27 µm preoperatively to 522.29 ± 43.12 µm after DMEK.

Aqueous Humor Collection and Cytokine Analysis

At the beginning of all surgeries, approximately 100–150 μl of aqueous humor was collected for quantitative and qualitative measurement of inflammatory mediators including tumor necrosis factor α (TNF-α), vascular endothelial growth factor (VEGF), interleukin-2 (IL-2), IL-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, granulocyte–macrophage colony-stimulating factor (GM-CSF), interferon-γ (IFN-γ), C-X-C motif chemokine 5 (CXCL5/ENA-78), basic fibroblast growth factor (FGF-basic), granulocyte colony-stimulating factor (G-CSF), interleukin-1-α (IL-1-α), IL-1-ra, IL-17, monocyte chemoattractant protein-1 (CCL2/MCP-1), macrophage inflammatory protein-1-α (CCL3/MIP-1-α), macrophage inflammatory protein-1- β (CCL4/MIP-1-β), thrombopoietin (TPO), transforming growth factor-beta 3, 2 and 1 (TGF-β-3, 2 and 1). As illustrated in Fig. 1, aqueous humor was collected from the anterior chamber at the beginning of cataract surgery and 3 months later at the beginning of DMEK using a cannula through the paracentesis. In the control group, aqueous humor was only collected at the beginning of cataract surgery. The aqueous humor samples were then frozen at − 80 °C until analysis.

Fig. 1.

Illustrative diagram depicting the study design

The aqueous humor analysis was conducted using Magnetic Luminex performance (Luminex Corporation, Austin, TX, USA) assay kits following the manufacturer’s instructions. In short, 100–150 µl of each aqueous humor sample was incubated in 96-well plates containing magnetic beads for 2 h at room temperature (RT). To conduct the assay, all reagents were prepared as instructed by the manufacturer. Next, 100 μl of either standard, control, or sample was added to each well of the microplate. Subsequently, 25 μl of a diluted Microparticle Cocktail was added to initiate the assay, followed by a 3-h incubation at RT on a shaker at 800 revolutions per minute (rpm). After incubation, the plate was washed thoroughly by carefully removing the liquid from each well and rinsing with 100 μl of Wash Buffer. This washing process was repeated three times to ensure proper removal of unbound substances. Following the wash steps, 50 μl of a diluted Biotin-Antibody Cocktail was added to each well. The plate was then covered and incubated for 1 h at RT on the shaker at 800 rpm. Then, the plate underwent another round of washing, mirroring the previous steps to eliminate any excess or unbound materials.

Next, 50 μl of Streptavidin-PE was added to each well and the plate was incubated for 30 min at RT on the shaker at 800 rpm. Following this incubation period, the plate underwent a final round of washing to remove any unbound Streptavidin-PE.

To conclude the assay, 100 μl of Wash Buffer was added to each well and the plate was incubated for an additional 2 min at RT on the shaker at 800 rpm before reading. Finally, the plate was read within 90 min using Luminex^® analyzer to quantify the assay results.

Statistical Analysis

For statistical analysis SPSS, version 29.0 for Windows (SPSS Inc., IBM, Armonk, New York, USA) was used. All measurements were described using mean, standard deviation, 1st, 2nd, and 3rd quartiles. Descriptive p values were calculated using Mann–Whitney U tests and Wilcoxon signed-rank tests. The significance level was set at 5% (p < 0.05).

Compliance with Ethics

Written informed consent was obtained from all patients prior to the surgical procedure. This study was approved by the local Ethics Committee of the University of Heidelberg and was performed in accordance with the Helsinki Declaration of 1964, and its later amendments.

Results

Table 2 provides a comprehensive overview of cytokine concentrations in the aqueous humor for all groups, including patients with FECD before (FECDph) and after cataract surgery (FECDpsph), as well as the control group. In the FECD group, the concentration of TNF-α (p = 0.021), IL-6 (p = 0.005), IL-8 (p = 0.001), CXCL5/ENA78 (p = 0.002), CCL2/MCP-1 (p = 0.001) and CCL4/MIP-1b (p = 0.037) were significantly higher 3 months after cataract surgery at the beginning of DMEK (Fig. 2).

Table 2.

Aqueous humor cytokine and chemokine levels in eyes with Fuchs’ endothelial corneal dystrophy (FECD group) and phakic eyes (control group)

Cytokine	FECDph median (min; max)	FECDpsph median (min; max)	Control group median (min; max)	p value
Tumor necrosis factor α (TNF-α)	0.00 (0.00; 1.29)	0.57 (0.00; 3.25)	0.32 (0.00; 1.03)	0.021*
Vascular endothelial growth factor (VEGF)	55.94 (32.46; 135.39)	61.98 (23.73; 116.32)	79.32 (0.58; 180.03)	0.806
Interleukin-2 (IL-2)	0.00 (0.00; 0.62)	0.00 (0.00; 0.00)	1.02 (0.40; 2.27)	0.389
Interleukin-1-beta (IL-1 β)	0.00 (0.00; 0.30)	0.01 (0.00; 0.47)	0.00 (0.00; 0.11)	0.436
Interleukin-4 (IL-4)	6.91 (0.00; 32.94)	5.06 (0.00; 37.13)	10.29 (0.00; 34.93)	0.653
Interleukin-5 (IL-5)	0.00 (0.00; 0.14)	0.00 (0.00; 0.33)	0.09 (0.04; 0.19)	0.624
Interleukin-6 (IL-6)	1.21 (0.00; 50.93)	18.91 (1.36; 158.32)	1.78 (0.59; 92.02)	0.005*
Interleukin-8 (IL-8)	3.79 (2.46; 9.23)	30.30 (6.37; 66.81)	4.89 (2.09; 33.66)	0.001*
Interleukin-10 (IL-10)	0.57 (0.27; 2.36)	0.52 (0.39; 0.90)	0.77 (0.33; 14.91)	0.653
Interleukin-12 (IL-12)	5.39 (0.00; 27.22)	5.00 (1.90; 12.78)	0.00 (0.00; 3.81)	0.512
Granulocyte–macrophage colony-stimulating factor (GM-CSF)	0.39 (0.00; 2.38)	0.61 (0.01; 2.39)	0.46 (0.05; 1.67)	0.595
Interferon -γ (IFN-γ)	0.00 (0.00; 35.71)	0.00 (0.00; 2.19)	0.00 (0.00; 4.05)	0.539
C-X-C motif chemokine 5 (CXCL5/ENA-78)	0.00 (0.00; 9.74)	15.14 (0.00; 24.59)	0.00 (0.00; 26.62)	0.002*
Basic fibroblast growth factor (FGF-basic)	8.82 (0.00; 342.59)	34.72 (0.00; 122.34)	0.00 (0.00; 46.00)	0.512
Granulocyte colony-stimulating factor (G-CSF)	21.08 (0.00; 62.12)	21.08 (0.00; 93.97)	11.06 (4.10; 41.33)	0.412
Interleukin-1-α (IL-1-α)	0.00 (0.00; 0.00)	0.00 (0.00; 0.00)	0.42 (0.00; 2.08)	1.000
Interleukin-1-receptor antagonist (IL-1ra)	290.48 (74.23; 2.516.49)	347.78 (26.53; 1.733.89)	107.62 (35.24; 756.03)	0.744
Interleukin-17 (IL-17)	0.00 (0.00; 10.16)	0.00 (0.00; 6.86)	0.00 (0.00; 0.72)	0.250
Monocyte chemoattractant protein-1 (CCL2/MCP-1)	325.80 (180.53; 633.47)	1.777.11 (423.32; 3.784.93)	257.88 (147.99; 939.07)	0.001*
Macrophage inflammatory protein-1-α (CCL3/MIP-1 α)	0.00 (0.00; 461.71)	0.00 (0.00; 138.51)	33.98 (0.00; 78.38)	0.250
Macrophage inflammatory protein-1-β (CCL4/MIP-1 β)	0.00 (0.00; 27.29)	11.34 (0.00; 52.72)	0.00 (0.00; 20.56)	0.037*
Thrombopoietin (TPO)	0.00 (0.00; 0.00)	0.00 (0.00; 0.00)	0.00 (0.00; 15.71)	1.000
Transforming growth factor-beta 3 (TGF- β 3)	312.15 (71.77; 431.12)	312.15 (71.77; 667.80)	306.33 (3.50; 583.16)	0.148
Transforming growth factor-beta 1 (TGF- β 1)	310.18 (0.00; 581.93)	364.69 (255.56; 636.07)	0.00 (0.00; 270.79)	0.187
Transforming growth factor-beta 2 (TGF- β 2)	674.87 (101.14; 1.960.84)	838.60 (316.32; 1.369.36)	514.81 (343.09; 1.169.11)	0.345

FECDph phakic patients with Fuchs endothelial corneal dystrophy, FECDpsph pseudophakic patients with Fuchs endothelial corneal dystrophy

p value: Group 1 (FECDph) and Group 1 (FECDpsph)

Significant differences are marked with * for p < 0.05

Fig. 2.

Boxplots showing inflammatory cytokine concentrations. A The cytokine concentrations of tumor necrosis factor α (TNF-α), B interleukin (IL)-8, C IL-6, D C-X-C motif chemokine 5 (CXCL5/ENA-78), E monocyte chemoattractant protein-1 (CCL2/MCP-1) and F macrophage inflammatory protein-1β (CCL4/MIP-1b) in aqueous humor were measured using a multiplex immunoassay and compared between the FECDph and FECDpsph. *indicates statistical significance (p < 0.05). FECDph phakic patients with Fuchs’ endothelial corneal dystrophy. FECDpsph pseudophakic patients with Fuchs’ endothelial corneal dystrophy

As illustrated in Fig. 3, in the control group, the aqueous humor exhibited significantly elevated levels of IL-2, IL-5, IL-8, IL-10, and IL-1-alpha compared to the FECDph group (all p values < 0.05). Conversely, IL-12, IL-1-ra, and TGF-β-1 demonstrated lower concentrations in the control group in contrast to eyes with FECD at the beginning of cataract surgery (p < 0.05) (Table 2).

Fig. 3.

Boxplots demonstrating inflammatory cytokine concentrations. The cytokine concentrations of A interleukin (IL)-2, B IL-5, C IL-8, D IL-10, and E IL-1-α in aqueous humor were measured using a multiplex immunoassay and compared between the FECDph and control group. *indicates statistical significance (p < 0.05). FECDph phakic patients with Fuchs’ endothelial corneal dystrophy

No statistically significant variations were noted in the concentrations of vascular endothelial growth factor (VEGF), interleukin-2 (IL-2), IL-1-β, IL-4, IL-5, IL-10, IL-12, granulocyte–macrophage colony-stimulating factor (GM-CSF), interferon-γ (IFN-γ), basic fibroblast growth factor (FGF-basic), granulocyte colony-stimulating factor (G-CSF), IL-1-α, interleukin-1-receptor antagonist (IL-1ra), IL-17, macrophage inflammatory protein-1-α (CCL3/MIP-1-α), thrombopoietin (TPO), transforming growth factor-beta 3, 2, and 1 (TGF-β-3, 2, and 1) between the FECDph and control group (all p values > 0.05).

Regarding clinical, slit-lamp-based indicators of anterior chamber inflammation, the study group displayed no signs of keratic precipitates (KPs), synechiae, flare, or graft rejection. Similarly, the control group demonstrated no signs of inflammation.

Discussion

DMEK represents a paradigm shift in the surgical treatment of corneal endothelial diseases [25–27]. This minimally invasive technique, characterized by the transplantation of healthy Descemet membrane and endothelium without any stromal components has been shown to be a superior alternative to traditional keratoplasty methods [28, 29]. Its notable advantages include rapid visual recovery and a significantly reduced risk of graft rejection [28, 30, 31]. However, a critical issue is the progressive decrease in corneal endothelial cell density (ECD) after DMEK, which is a key determinant of graft longevity [32–34]. Recent studies have elucidated the relationship between aqueous humor inflammation and ECD loss after corneal transplantation. Cytokines, in particular, play a central role in modulating the immune response, influencing processes such as tissue repair, fibrosis, and immune cell recruitment [35]. Elevated levels of the proinflammatory cytokine IL-8 in the aqueous humor have been associated with failed DMEK procedures, highlighting the potential detrimental effects of innate immune activation on ECD [36]. In addition, there is emerging evidence that successful DMEK can lead to regression of corneal neovascularization, highlighting the critical role of healthy corneal endothelial cells in modulating inflammatory responses within the cornea [37].

According to research on ocular immunology, the eye harbors distinct immunological characteristics stemming from its intricate anatomy, physiology, and the presence of specific components that uphold ocular homeostasis [2]. The interplay between the anatomical and physiological aspects of the eye contributes to the establishment of a unique barrier, which determines the formation of its immunological privilege [2]. Furthermore, the aqueous humor plays a crucial role in maintaining the cornea and lens function by providing anti-inflammatory and immunosuppressive properties, as well as facilitating the removal of harmful metabolic by-products and the supply of nutrients [38]. Various triggers, including environmental factors, surgeries, or underlying health conditions, have been identified as potential contributors to the influx of proinflammatory cytokines into the aqueous humor, thereby increasing the risk of developing ocular diseases [39, 40].

While the impact of aqueous humor inflammation on reduced ECD post-DMEK is widely recognized [28], there is a lack of comprehensive analysis of postoperative aqueous humor cytokine profiles. This study aims to fill this gap by characterizing cytokine dynamics in the aqueous humor of patients with FECD before and after cataract surgery. The results provide new insights into the postoperative condition of the eye after this procedure.

All cytokines and chemokines of the aqueous humor can be divided into groups, according to their main course in the inflammatory response [41]. By characterizing the cytokine profiles in FECD patients at multiple time points, we offer valuable insights into the dynamics of inflammation in these patients. In our study, the FECD group showed significantly higher concentration of TNF-α, IL-6, IL-8, CXCL5/ENA78, CCL2/MCP-1, and CCL4/MIP-1b 3 months after cataract surgery at the beginning of DMEK. TNF-α, IL-6, CCL2/MCP-1, and CCL4/MIP-1b are proinflammatory factors. Our findings align with recent literature, which demonstrates an upregulation of IL-8 and other chemokines in the aqueous humor of FECD patients undergoing cataract surgery [42]. IL-8, a potent chemoattractant, plays a critical role in the recruitment of immune cells, particularly neutrophils, which can exacerbate inflammation and potentially accelerate endothelial cell loss. TNF-α and IL-6 are key mediators of the acute-phase inflammatory response, promoting the activation and recruitment of immune cells [43]. Moreover, chemokines CCL2/MCP-1 and CCL4/MIP-1b are recognized as typical “chemoattractants”, meaning they prompt directed cell migration in cells capable of movement in response to environmental cues. The magnitude of the cellular response to the chemoattractant is contingent upon the gradient of its concentration in the extracellular milieu. The synthesis of chemokines undergoes intricate regulation at multiple levels, with various signals, such as hypoxia, bacterial by-products, oxidative stress, thrombin, and proinflammatory cytokines such as TNF-α, IL-1, INF-γ, and IL-6, stimulating their expression [44]. It is conceivable that these factors are significantly increased 3 months after cataract surgery in eyes with FECD due to the breakdown of the immune privilege mechanisms that could lead to increased local inflammatory reaction.

IL-6 is one of the multifunctional cytokines that are expressed by both immune cells (T-lymphocytes, dendritic cells, macrophages) and non-immune cells (epithelial cells, keratocytes and endothelial cells). IL-6 ensures the maintenance of anti-inflammatory T cells by inducing the synthesis of apoptosis inhibitor proteins (Bcl-2). IL-8 is an α-chemokine released by monocytes/macrophages, NCCs and Th2 subpopulation of CD4 + cells. This cytokine mediates inflammation by ensuring the migration of granulocytes, monocytes/macrophages and lymphocytes to the pathological focus. In addition, an increased concentration of MCP-1 and MIP-1β was found in patients with FECD compared to controls. The main source of these cytokines are macrophages/monocytes of the corneal stroma. These biologically active endogenous substances in turn serve as chemoattractants for monocytes and Th1 cells.

Matthaei et al. have also shown that patients with advanced FECD have an increased concentration of MCP-1 in the aqueous humor. This factor, which is one of the mediators of epithelial-mesenchymal transition, promotes the acquisition of phenotypic characteristics of fibroblasts by the endothelial cells. This leads to scarring of the extracellular matrix of the corneal stroma [45].

Interestingly, Fiolka et al. noted that while proinflammatory cytokines like IL-8 and MCP-1 were elevated, growth factors such as TGF-β1 were not significantly different in FECD patients compared to controls [42]. This suggests that the corneal microenvironment in FECD is more inflammatory rather than fibrotic, which could explain the progressive loss of endothelial cells and the failure of corneal regeneration despite the presence of TGF-β1, typically involved in wound healing and fibrosis. Our results further support this hypothesis, as the elevated cytokine levels observed 3 months post-cataract surgery in the FECD group could be contributing to the persistent inflammatory response. This chronic inflammation may compromise endothelial cell function and accelerate cell loss, particularly in the context of compromised immune privilege mechanisms in FECD eyes.

In our study, the FECD group demonstrated higher levels of IL-12, IL-1-ra and TGF-β-1 before cataract surgery in contrast to the control group. This is also in concordance with Matthaei et al. who showed that patients with advanced FECD have an increased concentration of TGF-β-1 in the aqueous humor.

In conclusion, significant differences in cytokine concentrations between phakic FECD patients and phakic patients without any ocular pathologies were shown. Additionally, the results of the present study indicate significantly increased concentration of TNF-α, IL-6, IL-8, CXCL5/ENA78, CCL2/MCP-1 and CCL4/MIP-1b 3 months after cataract surgery at the beginning of DMEK. The alteration of these cytokines may be the causative mechanism for persistent AC inflammation.

Therefore, it may be reasonable to combine cataract surgery with DMEK in phakic FECD patients or extend the interval between the two procedures to potentially enhance patient outcomes and minimize postoperative inflammation.

Limitations of the Study

One of the main limitations of this study is the lack of aqueous humor sampling at 3 months post-cataract surgery in the control group. While we were able to assess cytokine and chemokine profiles in the FECD group at this time point, the absence of comparable data from the control group makes it difficult to fully corroborate our findings. Without this data, we cannot definitively determine whether the elevated cytokine levels observed in the FECD group are unique to the disease or whether they may also be present in non-Fuchs’ patients post-cataract surgery. Future studies would benefit from including aqueous humor analysis in both groups at similar postoperative time points to strengthen the comparison and better understand the inflammatory dynamics in FECD versus non-Fuchs’ eyes. Additionally, the sample sizes for both the FECD and control groups could be larger. A larger cohort would improve the statistical power of our study and enhance the generalizability of the findings. Expanding the group sizes in future research would allow for more robust comparisons and provide deeper insights into the inflammatory processes involved in FECD versus non-Fuchs’ patients.

Author Contributions

Conceptualization: Lizaveta Chychko, Victor A. Augustin, Gerd U. Auffarth; investigation: Lizaveta Chychko, Victor A. Augustin; data analysis: Lizaveta Chychko, Victor A. Augustin, Hyeck-Soo Son; resources: Gerd U. Auffarth; draft preparation: Lizaveta Chychko, Victor A. Augustin; review and editing: Victor A. Augustin, Hyeck-Soo Son, Ramin Khoramnia, Maximilian Friedrich; supervision: Victor A. Augustin, Ramin Khoramnia and Gerd U. Auffarth. All authors have read and agreed to the published version of the manuscript. All authors attest that they meet the current ICMJE criteria for authorship.

Funding

No funding or sponsorship was received for the study or publication of this article.

Data Availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Conflict of Interest

Lizaveta Chychko, Hyeck-Soo Son, Maximilian Friedrich, Ramin Khoramnia, and Victor A. Augustin have nothing to disclose. Gerd. U. Auffarth receives funding from the Klaus Tschira Stiftung, Heidelberg, Germany. Funding organizations had no role in the design or conduct of this research.

Ethical Approval

Written informed consent was obtained from all patients prior to the surgical procedure. This study was approved by the local Ethics Committee of the University of Heidelberg and was performed in accordance with the Helsinki Declaration of 1964, and its later amendments.