Near work, light levels and dioptric profile - Which factor dominates and influences the short-term changes in axial length?

Repeatability and agreement of the MYAH and Lenstar

SIGNIFICANCE

Validation of new biometry instruments against the gold standard and establishing repeatability are important before being utilized for clinical and research applications.

PURPOSE

This study aimed to investigate intersession repeatability of the MYAH optical biometer and corneal topographer and examine agreement with the Lenstar LS900 optical biometer in healthy young adults.

METHODS

Forty participants (mean age, 25.2 ± 3.1 years) presented for two visits, 2 to 4 days apart. At each visit, measurements for right eyes were collected with the MYAH and Lenstar LS 900 and included axial length, corneal power, white-to-white distance, and pupil diameter. Bland-Altman analysis was used to assess the intrasession agreement between the MYAH and Lenstar for each parameter and intersession repeatability for the two devices. For each device, coefficient of variation and intraclass correlation coefficient were calculated, and paired t tests between visits were performed to assess intersession repeatability.

RESULTS

Good agreement (mean difference [95% limits of agreement]) between the MYAH and Lenstar was found for axial length (-0.01 [-0.07 to 0.04] mm), corneal power (-0.02 D [-0.15 to 0.19 d]), white-to-white distance (-0.13 [-0.43 to 0.17] mm), and pupil diameter (-0.27 [-0.79 to 1.33] mm). The limits of agreement, coefficient of variations, and intraclass correlation coefficients for MYAH-measured parameters were -0.04 to 0.04, 0.06%, and >0.99 for axial length; -0.24 to 0.19, 0.18%, and >0.99 for corneal power; -1.05 to 1.15, 0.57%, and 0.96 for white-to-white distance; and -0.17 to 0.21, 7.0%, and 0.76 for pupil diameter, with no significant difference between visits (p>0.05 for all), indicating good intersession repeatability. Similar intersession repeatability was also noted for Lenstar.

CONCLUSIONS

Findings show good intersession repeatability of the MYAH and good agreement with the Lenstar for axial length, corneal power, and white-to-white distance in young adults. Pupil diameter was more variable, likely due to the dynamic nature of the pupil. This study provides validation and supports the use of the MYAH for ocular biometry.

Factors influencing dominant eye selection in refractive surgery patients: A correlation analysis

OBJECTIVE

This study aims to reveal the factors influencing the selection of the dominant eye in refractive surgery patients, and enhance the accuracy of clinical evaluation and surgical treatment.

METHODS

A retrospective study method was employed. The ocular biometric parameters were analyzed in 4,114 patients who underwent refractive surgery at the affiliated hospital of Southwest Medical University from 2019 to 2023.

RESULTS

The study found that 79.07% of the patients had the right eye as the dominant eye, while 20.93% had the left eye. Although there was no significant difference between the dominant and non-dominant eyes in terms of uncorrected visual acuity and Kappa angle, the dominant eye performed better in aspects such as spherical lens, eye axis, and corneal flat curvature. Furthermore, univariate and multivariate logistic regression results showed that best-corrected visual acuity, pupil diameter, horizontal displacement x-value of the Kappa angle, and astigmatism vector J45 were significant influencing factors for the selection of the dominant eye.

CONCLUSION

There are numerous factors affecting the dominant eye, and the most important core factor is J45. This study comprehensively evaluated the possible factors affecting the dominant eye in patients undergoing refractive surgery, which provides a foundation for the designation of refractive surgical modalities and assurance of surgical outcomes, and opens up new perspectives on understanding the mechanisms of the formation and development of the dominant eye.