Pterygium is a prevalent condition in tropical countries. Although it is clear to diagnose and treat, recurrence is a persistent problem and can cause vision impairment complications, such as cornea opacity, astigmatism and high order aberrations. The aim for a perfect surgery technique encourages ophthalmologists to keep developing new strategies that could set the surgery into a less painful, more effective and feasible treatment.
Placing the graft with commercial fibrin glue has benefits already shown. Moreover, Rubin et al. demonstrated a significant reduction in the surgical time when the fibrin glue was used (19.05 minutes) compared to the suture group (48.15 minutes), in addition to less discomfort and less ocular hyperemia in all post-operative visits. Although the total time would not differ between techniques, the hands-on surgical time was shorter, and the graft attachment maneuvers were faster and probably caused less graft touching with the glue technique. Moreover, surgery was performed by a single experienced surgeon in our study, and if we consider surgeons in training, sutures would probably take a significantly longer time.
We found lower rates of postoperative pain scores in the glue group, similar to the literature.[17, 19] Pain was lower and might be associated with lower manipulation and the absence of suture. Edema, however, was higher in the glue group. This might be related to the uniform edge sealing achieved with fibrin glue, preventing blood and fluid drainage underneath the graft. The findings are similar to the ones previous reported, with the glue group presenting significant lower rates of pain, discomfort, inflammation and subconjunctival hemorrhage.
There was no statistical difference between the groups concerning the graft attachment rates, although we found greater numerical losses in the autologous glue group. Mahdy and Wagieh prepared the autologous glue in a pathology laboratory, through centrifugation (similar to the one used in the present study), to adhesion the amniotic membrane and conjunctival graft, and they also had a numerically not significantly higher rate of graft loss. Despite those numbers, they considered the autologous glue safe. Similarly, the study by Boucher et al. found higher rates of graft loss in the autologous glue (30%; p = 0.020), and they suggested that graft size and postoperative patch duration could be associated factors. In opposition to those, Alamdari et at. performed an RCT comparing suture versus autologous fibrin glue (AFG) and found that the conjunctival autografts in both groups were successfully attached. There were, however, two differences reported by the Alamdari study compared to ours: surgeries were performed by two surgeons and the patients underwent peribulbar blockage anesthesia. Analogous, Kurian et al., found no difference in the groups in terms of graft displacement. When comparing those two last studies, the autologous glue preparation may differ.[19, 26]
Regarding pterygium recurrence, the presence of the conjunctival autograft technique has been associated with lower recurrence rates, ranging from 9.2–13% [1, 5, 27–29]. Among the techniques of GAC fixation, the one associated with the least amount of recurrence is a matter of debate. We did not find a statistically significant difference between groups. Still, it tends to occur more frequently in patients whose graft was lost, mainly when the graft loss happened within the first week. One hypothesis is that eye movement might have played a role in early graft detachment and, consequently, pterygium recurrence. In the present study, we performed the surgery without peribulbar anesthesia, with might have allowed eye movements under the patch during the first 24 hours.
Another fact that must be considered is glue preparation, because there is no global consensus on the best way to provide it. Some use only the patient’s autologous blood and place the graft on the bare sclera, with minimal cautery.[26, 31, 32] Other studies prepare an autologous fibrin glue: Almadari et al. drew up the glue one week before the procedure through the peripheral blood centrifuging for 30 min and PPP separation, and the fibrinogen concentrate was prepared by the method of cryoprecipitate. Our study did not use the cryoprecipitate, and the patient’s blood was collected right before the surgery. The time before surgery for handling and preparing the autologous fibrin glue could have negative implications for the practice of this technique. There was neither graft loss nor recurrence in the AFG group in the Alamdari study, and those are the main differences we found, besides more prolonged topical corticosteroids for their patients.
Even though the study is an RCT, we recognize the limitations involving the number of patients and the absence of different glue techniques. Topical anesthesia might also impact, but it represents the daily clinical practice in our service. Autologous fibrin glue is an available option for ACG fixation in particular contexts where fibrin glue is unavailable and it could offer advantages compared to suture, as the reduction of pain, necessity of suture removal and potentially less risk of infection or suture related granulomas. We recognize that larger studies are warranted to confirm these findings.
Therefore, the fibrin adhesive remains the mainstay for pterygium surgery until a more comprehensive recommendation on the use of autologous blood emerges. Improvements in the autologous glue technique are necessary before consistently applying it.