ESCRS - FP04.08 - COMPARISON OF CHORD MU AND CHORD ALPHA VALUES IN MYOPIC AND HYPEROPIC EYES.

COMPARISON OF CHORD MU AND CHORD ALPHA VALUES IN MYOPIC AND HYPEROPIC EYES.

Published 2026 - 30th ESCRS Winter Meeting

Reference: FP04.08 | Type: Free Paper | DOI: 10.82333/z0ns-s012

Authors: Leyla Bahar* 1 , Semih Çakmak 1 , Emre Altınkurt 1

1Department of Ophthalmology,İstanbul Faculty of Medicine, İstanbul University,Istanbul,Türkiye

Purpose

To compare Chord µ and Chord α values obtained with Pentacam AXL (Oculus, Germany) in myopic and hyperopic eyes and to evaluate the correlation of these parameters with anterior segment parameters.

Setting

Department of Ophthalmology, İstanbul Faculty of Medicine, İstanbul University, İstanbul Türkiye.

Methods

In the study 25 hyperopic eyes (Group 1 - 50 eyes) and 25 myopic eyes (Group 2 - 50 eyes), matched for age and gender, were included. Eyes had no ocular pathology and intraocular pressures were normal. Subjects with a spherical values between -5.00 and +5.00 diopters were included in the study. Ophthalmologic examination findings, anterior segment topography parameters, and Chord µ and Chord α values were noted and compared between the groups.

Results

Of the eyes, 22 were female and 28 were male and the mean age was 28.66 ± 5.93 years and there was no significant difference between the groups. The average axial length (AL) value was 22.60 ± 1.22mm and 23.97 ± 0.31mm (p=0.002); the average flat keratometry value (K1) was 41.85 ± 1.22D and 43.00 ± 1.80D (p<0.001); the steep keratometry value (K2) was 43.17 ± 1.46D and 44.28 ± 2.01D (p<0.001); the maximum keratometry value (Kmax) was 44.10 ± 1.74D and 44.77 ± 2.06D (p=0.024); the white-to-white measurement (WTW) was 11.84 ± 0.56mm and 12.00 ± 0.36mm (p=0.246); the anterior chamber depth (ACD) was 2.80 ± 0.49mm and 3.22 ± 0.29mm (p=0.002) for Groups 1 and 2, respectively. The chord µ  value was µ 0.26±0.14  and 0.13±0.06 (p<0.001); chord α value was 0.50±0.14 and 0.32±0.10 (p<0.001) for Groups 1 and 2, respectively. In hyperopic eyes, an increase in spherical value showed a significant correlation with Chord µ and α (p=0.008 and 0.059, respectively), while no correlation was found with cylindrical values (Chord µ and α: p=0.669 and 0.367, respectively). In myopic eyes, no significant correlation was observed between spherical and cylindrical values with Chord µ and α (p>0.05 for all). No statistically significant relationship was found between corneal asphericity (Q) values and spherical (p=0.753 and p=0.750, respectively) and cylindrical refractive values (p=0.979 and p=0.256, respectively) in both groups.

Conclusion

A significant correlation was found between the spherical values and Chord measurements in the hyperopic eyes, but no significant correlation was found in the myopic eyes. No significant correlation was observed with the cylindrical value. Since Chord µ and Chord α values were found to be significantly higher in hyperopic eyes and correlated only with spherical values in this group, these measurements should be taken into account in refractive and lens surgeries, especially hyperopic patients.