There are researches in literature which demonstrate astigmatism caused by pterygium decreased after surgically pterygium excision [15, 19–21]. It has shown that removal of pterygium surgically with limbal autograft treatment is more secure and effective among other methods regarding recurrence and cosmetic [21, 22]. However, the preference of graft location is still controversial today. Hence we aimed to research the effect of taking graft from a different location on cornea topographic data and astigmatism data which are the data that reveals the effect of the operation on visual quality. As the first study of literature which we investigate the effect of pterygium surgery with superior and inferior bulbar autograft on corneal astigmatism, when we evaluate cornea anterior face, flattest (K1) meridians were statistically steeper after the operation in the cases of taking autograft from both superior and inferior, meanwhile no significant difference was detected in the steepest (K2) meridian. While there was no difference in Maximum K values for the superior conjunctival graft group, a decrease was detected for the inferior conjunctival graft. At the same time, Rper values showed a statistically significant decline in both groups. As the cap of the pterygium approaches the corneal apex, a meniscus formed by the tear film layer between the raised pterygium tissue and the cornea causes significant flattening. This situation improves after the pterygium surgery and results in improvement of astigmatism [4]. Our research as well supports that a significant decline performs in K1, astigmatism value and Rper value of the anterior face.
The first researches which have investigated the change of posterior and anterior face astigmatism with pentacam after pterygium surgery belonged to Kheirkhah et al [23, 24]. In the research three different surgical techniques have been used which are bare sclera with mitomycin C, amnion graft, and free conjunctival graft [1]. As a result of the study, only astigmatism and axis values have examined in 96 patients and it was reported that anterior astigmatism decreased significantly, and posterior astigmatism was decreased but it was not a statistically significant difference [24]. In our study, unlike the study of Kheirkhah et al., we evaluated not only astigmatism values but also K1, K2, Kmax, Rper, Axis and Astigmatism changes for anterior and posterior surfaces. While K1 values show a significant difference for the anterior face, there was not any significant change for K2 values. Astigmatism values have decreased for both groups. In addition, Rper slope has also decreased which we think it is related to the disappearing of the mechanical effect of the pterygium. Rper has shown a change only in the superior conjunctival graft group for posterior face values, but there was no statistically significant difference for other values even if changes have shown. In the study of Kheirkhah et al.24, even if a decrease from 0.35 D to 0.32 D was observed, no statistically significant difference was found. In our study similar to the study of Kheirkah, even though a decrease in posterior astigmatism for 2 groups was observed, it wasn't statistically significant.
Levinger et al [9] have evaluated surgery-induced astigmatism (SIA) and they have found a significant difference. In our study different from the study of Levinger et al., although we have obtained the change in the posterior face less than a significant change in the anterior face after pterygium surgery, we think the graft location does not affect anterior and posterior face corneal astigmatism. Our study’s one of the limiting factors was the low number of patients, but if there can be more patients in studies, they can enlighten this subject more.
In the research of Misra et al. [3], they only took superior graft and they solely evaluated ISV and IVA which is from the corneal front face regularity indices and astigmatism data evaluated with pentacam. As a result, they have detected a decline in all data. In our study too we have found a decline in ISV, IVA and astigmatism values after surgery of graft taking from both superior and inferior. In addition, in our research as different from Misra et al. [3], we have examined IHD and IHA. Moreover, we have detected that IHA was not changing in the superior graft group, but the IHD indice has a decline. In the inferior graft group, IHA and IHD values have declined. However, when the postoperative superior and inferior groups were compared with each other, no significant difference was demonstrated in terms of anterior surface indices. We assessed this situation as assimetry which occurs independently from graft location recovers after the successful pterygium surgery.
In conclusion, we aimed to investigate whether astigmatism changes are a factor when deciding on the graft location in this study and as a result, we demonstrated that a successful pterygium surgery with limbal conjunctival autograft is sufficient for the management of astigmatism regardless of whether the graft is taken from the superior or the inferior. The preference of surgeons and the clinical case of the patient should be considered when deciding graft location.
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