Evaluating coagulogram abnormalities as a risk factor for recurrence of full-thickness macular hole using autologous conditioned plasma

Introduction 

Full-thickness macular hole (FTMH) is a pathology of a macular defect developing throughout the entire thickness of the neuroepithelium. This nosology affects 7.4 people per 100 thousand population annually and leads to the development of central scotoma, reduced visual acuity and even blindness [1]. Currently, this pathology can be successfully treated by vitreoretinal intervention resulting in the anatomical profile restoration of the macular zone and improved visual acuity. However, according to the latest large-sample studies, incomplete closure of the macular hole (MH) after surgery is observed in 6–11% of cases [2–3]. The following risk factors for incomplete closure of the FTMH after surgery are known: rigidity of the edges of a long-standing MH, large MH diameter (>400 μm), stage 4 idiopathic MH (sensu J.D. Gass), failure to comply with the recommended face-down position by the patient in the early postoperative period, the presence of high myopia, and the patient’s Negroid race [4, 5]. Repeated surgeries performed to fix incomplete closure of the FTMH yield additional financial costs for the medical institution and increase the risk of iatrogenic complications, such as retinal tear and detachment [3, 6–8].

For complete closure of MH, various surgical techniques have been developed: use of an internal limiting membrane (ILM) flap, application of autoplasma, relaxing retinal incisions, ILM peeling with mechanical action on the edges of the hole, and MH hydrodissection. 

The use of platelet-rich autoplasma, also known as platelet-rich plasma (PRP) has become widespread in FTMH surgery. There are two main technologies for obtaining autoplasma for closure of macular defects: PRP technology and autologous conditioned plasma (ACP) technology. Both are effective in closure of idiopathic FTMH of various sizes in clinical studies [9–12]. ACP technology is most often used for surgical treatment of MH at Moscow City Center for Ophthalmology of Botkin Multidisciplinary Scientific and Clinical Center of Moscow.

A potential advantage of ACP technology over PRP is the composition of autoplasma obtained by centrifugation. Compared with PRP mass, ACP mass has an increased content of platelets (p<0.001), and blood clotting factors and growth factors (insulin-like growth factor 1 [p<0.001], transforming growth factor β1 [p<0.001]), as well as a lower number of leukocytes (p<0.001) [13]. The higher content of platelets, clotting factors and growth factors is potentially associated with the formation of a denser clot and good healing of the retina in the MH area.

Analysis of current scientific publications reveals that the role of platelets and blood clotting factors outside the hemostasis system is currently actively studied. Some studies confirmed the role of individual coagulation factors in the processes of reparation and revascularization in various tissues, which indicates the potential effect of autoplasma components not only on the mechanical convergence of the MH edges, but also on the restoration of the retinal neuroepithelium in the defect area [14–18].

There are also recently published reports on the effect of autoplasma composition on the MH closure and retinal reparation [19]. However, we are not aware of studies examining the effect of the initial procoagulant properties of the patient’s blood on the formation of a clot in the MH area and the restoration of the macular profile when using ACP mass.

According to the Moscow City Center for Ophthalmology of Botkin Multidisciplinary Scientific and Clinical Center of Moscow, 148 eyes with newly diagnosed FTMH were operated on from January 01, 2023 to January 01, 2025. Complete closure of the MH after surgery was observed in 133 (89.9%) eyes. Incomplete closure of the MH was confirmed in 15 (10.1%) eyes. Thus, preventing recurrence of MH and increasing the number of successful surgeries is a promising area of research. 

Objective: to evaluate the abnormalities in the activity of blood coagulation factors as a potential risk factor for incomplete closure and the development of FTMH recurrence after surgery using ACP mass.

Materials and methods

We conducted a single-center retrospective cohort study involving 62 patients (62 eyes) with primary FTMH. The inclusion criteria for the cohort were the presence of idiopathic FTMH confirmed by optical coherence tomography (OCT), anterior-posterior axis of the eye less than 26 mm, OCT examination of the macular zone 7 days and 1 month after surgery. All patients underwent the following surgical intervention: microinvasive closed subtotal vitrectomy + removal of the epiretinal membrane and ILM + application of ACP mass to the MH area + air tamponade. Patients were distributed among two groups. The 1st (main) group included patients who exhibited an increase or decrease in the values of coagulogram parameters before surgery (n=31). The 2nd (control) group included patients with coagulogram parameters not exceeding the reference values (n=31). The blood serum coagulogram was assessed the following parameters: activated partial thromboplastin time (APTT), prothrombin time (PT), international normalized ratio (INR), thrombin time (TT), and fibrinogen level in the blood. There were no intraoperative complications in any patient of the cohort. Patients were discharged on the next day after vitrectomy. They were reexamined 7 days and 1 month after surgery using a repeat OCT study to assess the dynamics of MH closure.

The main group included 7 (22.60%) men and 24 (77.40%) women aged 67.39±5.96 years (range: 56–80 years). The mean MH diameter was 794.23±315.69 μm (range: 457–1829 μm). The control group included 8 (25.80%) men and 23 (74.20%) women aged 66.97±5.06 years (range: 52–75 years). The mean MH diameter was 793.65±221.51 μm (range: 440–1579 μm). It is worth noting that the mean MH size in both groups was similar; hence, the potential influence of this factor on the outcome of surgical treatment was nonexistent. 

Statistical data processing was carried out using the StatTech 4.0.7 (StatTech LLC, Russia) and Microsoft Excel 2019 (Microsoft, USA) software. The relationship between the surgical treatment outcomes and the presence of abnormal values of individual coagulogram parameters was assessed using the Spearman’s rank correlation coefficient. To assess the significance of differences for categorical variables, the Pearson’s χ² method was employed. Differences between parameter values were considered statistically significant at p<0.05.

Results

When comparing the outcomes of surgical treatment using autoplasma, we found that among patients with coagulogram abnormalities, the development of recurrent MH was more frequently observed than in patients of the control group (p=0.005) (Table 1).

Table 1. Evaluation of surgical treatment outcomes in two groups of patients

In the main group of patients, we evaluated the relationship between the surgical treatment outcomes and the presence of abnormalities in individual coagulogram parameters (Table 2).

Table 2. Evaluation of surgical treatment outcomes depending on coagulogram abnormalities

 *р<0.05; APTT, activated partial thromboplastin time; PT, prothrombin time; INR, international normalized ratio; TT thrombin time.

We discovered that recurrence of MH was 6.1 times more often detected among patients with an increased PT (p=0.042), along with the amount of fibrinogen in the blood serum below 2.0 g/L (p=0.049) (Figures 1 and 2).

Discussion

The main effect of ACP mass in MH closure is the initial contact of the platelet component with the retinal defect areas, its aggregation and activation, along with the formation of a loose platelet clot initially closing the MH. Simultaneously with this process, activation of blood plasma coagulation factors (coagulation component of the coagulation system) takes place, due to which the formation of insoluble fibrin and a dense thrombus comprising of fibrin and various blood cells are observed. It is worth noting that activated coagulation factors (in particular, factor XIIIa) also trigger the platelet retraction in the clot, which contributes to the convergence of the MH edges [14, 15]. 

In recent years, the role of coagulation system factors outside the hemostasis system is actively studied. There are numerous publications that confirm the active role of individual coagulation factors in regeneration, remodeling and revascularization of damaged tissues [14–18]. 

Studies confirming the role of coagulation factors in the regeneration of damage to the nervous tissue of the central nervous system (CNS) embryologically similar to the cells of the retinal neuroepithelium deserve special attention. Experiments revealed the role of factors X, VII, TF in the restoration of the CNS cells after a stroke. For instance, a complex of activated blood coagulation factors, TF-VII-X, is capable of triggering the expression of protease-activated receptor 2 (PAR2) and activation of a cascade of molecular reactions resulting in revascularization and restoration of astroglia and neurons, a reduced formation of glial fibrosis areas (as compared with the control group, in which a knockout of the gene activating the pathways associated with PAR2 was performed) [18, 20]. There are also publications reflecting the role of thrombin (IIa) activity on the expression of protease-activated receptor 1 (PAR1), due to which the process of nerve tissue cell retinal ganglion cell remodeling in neurodegenerative diseases is regulated [16, 17]. 

Thus, a low number and/or activity of blood coagulation factors is associated with the formation of a less dense thrombus comprising of fibrin and various blood cells in the FTMH area, a lower potential for convergence of the MH edges, along with a decrease in the regeneration of the neuroepithelium in the MH area. Consequently, abnormalities of the coagulogram, reflecting reduced activity of the blood coagulation system, can be a marker for the development of FTMH relapse in the case of vitreoretinal intervention with autoplasma.

According to our data, the presence of abnormalities in the coagulogram before surgery in patients with FTMH is a potential risk factor for incomplete closure of the neuroepithelial defect, since an association with a higher risk of recurrent MH after surgery using ACP mass was established in this group of patients (p<0.005). When analyzing the relationship between abnormalities in individual coagulogram parameters and incomplete FTMH closure, we revealed some statistically significant patterns (p<0.05). Among patients with an increased PT, relapse of MH detected within the first month after surgery occurred more often (p=0.042). Determining the PT value in the blood serum is a screening study reflecting the activity of the extrinsic pathway of coagulation hemostasis (activity of coagulation factors VII, X, V, prothrombin and fibrinogen). An increased PT is indicative of a reduced concentration and/or activity of the previously described coagulation factors associated with a hypocoagulable state of blood plasma and a low potential for the formation of a stable blood clot. It is worth noting that a lower activity and/or concentration of factors VII and X may adversely affect retinal reparation due to reduced activation of cascades associated with PAR2 [18, 20]. 

Also, a reduction of the blood serum fibrinogen content in patients before surgery was statistically significantly associated with higher a risk of developing a relapse of FTMH (p=0.049). Fibrinogen in its active form (fibrin) helps stabilize the platelet clot and also represents a matrix for the production of collagen and other connective tissue molecules during tissue defect remodeling [15]. As a result, its low initial concentration in the blood plasma is associated with lower prospects for the formation of a thrombus in the FTMH area and regeneration of the neuroepithelium. 

Hence, we propose that the use of ACP mass may be less effective in closing MH in the presence of coagulogram abnormalities suggesting hypocoagulation (evidenced by an increased PT), as well as with a reduction in the fibrinogen level. 

Conclusion

The use of ACP mass is an effective method of closing idiopathic FTMHs of various sizes. However, as with other surgical methods of treating macular defects, MH recurrence may develop after this type of surgical intervention. The causes of this phenomenon are still not fully understood. 

Our data suggest that the presence of abnormalities in the coagulogram is a potential risk factor for unsuccessful MH closure when using ACP mass. Among patients with an increase in PT and a reduction in the fibrinogen content, MH recurrence was detected more often (p=0.042 and 0.049). That is why the presence of abnormal values in the coagulogram suggesting hypocoagulation, as well as the presence of reduced fibrinogen content before surgery, can be considered by the surgeon as a potential risk factor when using autoplasma for the closure of the MH, prompting medical professional to use alternative surgical techniques or their combinations (e.g., an inverted ILM flap in combination with autoplasma) to reduce the risk of the FTMH recurrence, thereby preventing a reoperation. 

Of course, the platelet component of autoplasma plays an essential role in closing the macular zone defect. However, the role of coagulation factors is also important, since they contribute to the formation of fibrin and stabilization of the thrombus in the MH area, play a role in clot retraction by bringing the edges of the neuroepithelium closer together, and stimulate the initiation of regeneration processes in the MH area. The question of the effect of individual factors on the processes of MH reparation is open and requires further study. It is also worth noting that coagulogram data are not highly specific and cannot accurately reflect the state of the quantity or activity of individual components of coagulation hemostasis. However, this laboratory test is highly available and is included in the mandatory minimum of clinical tests before surgery according to current clinical guidelines.

Author contributions: All authors contributed equally to the preparation of the manuscript.

Conflict of interest: None declared by the authors.