Use of angle kappa in myopic photorefractive keratectomy

Abstract

PurposeTo explore utilization of the coaxially sighted corneal light reflex (CSCLR) for centration during myopic photorefractive keratectomy (PRK) for patients with relatively high angle kappa (κ) values.MethodsPatients were stratified into two groups preoperatively, on the basis of angle κ values.Group A was composed of 166 eyes with an angle κ value <5°. Group B consisted of 182 eyes with an angle κ value >5°. Intraoperative centering of ablation was performed within group A by utilizing the pupillary center, and within group B by using the CSCLR. Visual acuities were evaluated and compared at 6 months and 12 months postoperatively between groups.ResultsMean uncorrected visual acuities (UCVA) for all patients at 6 months and 12 months were −0.073 logMAR and −0.080 logMAR, respectively. A total of 98.9% of patients had a UCVA of 0.00 logMAR (≈20/20 Snellen) 12 months postoperatively. There was not a significant between-group difference in regard to residual refractive error at 6 months or 12 months (P=0.53 and P=0.97), or in UCVA at 6 months and 12 months (P=0.76 and P=0.17). There were no subjective complaints of monocular diplopia, glare, or haloes within either group at any time during follow-up.ConclusionAvailing use of the CSCLR for centration of ablation within myopic patients with high angle κ values may aid in providing better refractive outcomes after performance of PRK.

Dynamic distribution and correlation analysis of the angle kappa in myopia patients undergoing femtosecond-assisted laser in situ keratomileusis

“…During the operation, the pupil dynamics were monitored to adjust the angle kappa and calibrate the ablation centration in real time to ensure that each scanning-spot excimer laser was in the correct position. [19] The angle kappa is not a fixed value, and it changes under different conditions. [20] Influenced by factors such as intraoperative illumination, surgical stimulation, eye type, emotional tension, and accommodation convergence caused by close gaze indicator lights, there can be dynamic changes of pupil size and central position.…”

“…Therefore, according to the pupil size, centre position and dynamic change of angle kappa of the patients who are suitable for excimer laser surgery, obtained the individualized pupil centre displacement curve. During the operation, the pupil dynamics were monitored to adjust the angle kappa and calibrate the ablation centration in real time to ensure that each scanning-spot excimer laser was in the correct position [19] …”

Correlation Analysis of Refractive and Visual Quality after Wavefront-Optimized Laser In Situ Keratomileusis for 50% and 100% Angle Kappa Compensation

“…However, angle kappa is not a fixed value, and it will change under different conditions. It can be affected by factors such as light during surgery, surgical stimulation, emotional tension, and convergence adjustment caused by watching the indicator at close range [ 6 – 8 ]. According to the data regarding changes in angle kappa, can we obtain individual kappa angle adjustment vector percentages, find the cutting center point closest to the visual axis, and ensure that each excimer laser spot is in the exact position?…”

Repeatability and Agreement of Chord Mu between Scheimpflug Tomography and Swept-Source Optical Coherence Tomography

“…Understanding the concept of angle kappa and its measurement is crucial for treatment planning because variation in angle kappa may affect surgical outcomes in keratorefractive and cataract surgeries [1][2][3][4][5][6]. A large angle kappa leads to a decentered ablation, which may result in undercorrection and irregular astigmatism [1,2].…”