## 4 Discussion  
This study demonstrated that elite football players exhibit good static visual acuity and a predominance of emmetropia, with low levels of anisometropia and symmetrical refractive components between the eyes. Postural stability metrics indicated overall good balance, although some medio-lateral and antero-posterior variability was observed, likely reflecting sport-specific neuromuscular adaptations. Crucially, significant correlations were found between visual acuity, refractive errors, binocular asymmetries, and key postural stability parameters, highlighting the central role of visual function in maintaining balance in this athletic population. The primary aim of this study was to explore the relationships between visual acuity, refractive errors, and postural stability in elite football players, addressing a critical gap in the understanding of visual-postural interactions in this specific population. Previous research has consistently shown that athletes typically exhibit good visual acuity and low refractive errors, with the majority being emmetropic [31; 32; 33]. However, the specific role of refractive status and visual acuity in influencing postural stability has remained insufficiently investigated. Our results confirmed that elite football players not only exhibit excellent static visual acuity, consistent with previous studies describing above-average visual performance in athletes, thereby reinforcing the notion that optimal visual function is a characteristic of high-level sporting populations. Moreover, refractive status--particularly hyperopia and binocular asymmetries--was significantly associated with variations in postural stability. These results confirm that this study's primary objective was successfully achieved, offering new evidence that supports the integration of comprehensive vision assessments into strategies aimed at optimizing performance and preventing injuries in high-level athletes. Additionally, the low prevalence of anisometropia and the symmetry in refractive components between eyes further underline the importance of maintaining optimal binocular function for precise spatial awareness and stability during dynamic activities. Moreover, the observed postural parameters indicated a relatively balanced overall stability, with some variability in specific metrics that may reflect sport-specific adaptations. Among the most relevant stablometric findings, Xmean revealed a slight leftward tilt,  
Figure 2: Scatter plot showing the correlation between anisoastigmatism J45 (difference in oblique astigmatism between eyes) and sway surface area (Surface) in elite football players. while Ymean indicated a pronounced forward lean. These patterns may reflect postural adaptations specific to football, where forward movements and lateral shifts are essential. The metric \"mean distance of the center of pressure from the central point\" suggested moderate overall stability, whereas Surface highlighted greater instability in some players, emphasizing variability in postural stability strategies. The stabilizer path lengths of the CoP (Length, LengthX, and LengthY) provided further insights into postural dynamics. The total CoP path length (Length) reinforced the trend of moderate instability observed in some participants. In the frontal plane (LengthX), the mean value was higher compared with the sagittal plane (LengthY), indicating that medio-lateral sway was more pronounced than antero-posterior sway. This may reflect the demands of lateral movements inherent to football and is consistent with previous studies reporting increased medio-lateral sway in athletes from sports requiring frequent lateral shifts and directional changes [34; 35]. Energy expenditure required to maintain balance (measured as the ratio of CoP path length to sway surface area, LFS) was found to be efficient and close to optimal, suggesting that most participants demonstrated effective neuromuscular control.