Angle kappa changes after photorefractive keratectomy for myopia

Zarei‐Ghanavati, Siamak; Gharaee, Hamid; Eslampour, Alireza; Abrishami, Mojtaba; Ghasemi-Moghadam, Soamaye

doi:10.1007/s10792-013-9775-x

Cited by 17 publications

(18 citation statements)

References 13 publications

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“…Our results also show a positive correlation between lateral WTW and pupil diameter change. The related results have not been reported at home and abroad.This conclusion guides us to treat patients with large cornea during the operation to ruduce the dynamic changes in pupil size whit a darker environment as much as possible in order to improve the e ciency of pupil matching [26] .There is no correlation between the SE and the change of pupil diameter, but there is a negative correlation between the SE and Measured Centroid Shift.It has been reported in the literature that the refractive state has a signi cant correlation with the angle kappa, which is consistent with the results of this study [15] .Therefore, We speculate that the dynamic change of pupil center of Measured Centroid Shift is small for people with high myopia.Therefore, it can be understood that the dynamic change of angle kappa is correspondingly reduced, and the e ciency of pupil matching is higher. It is suggested that the proportion of compensating angle kappa vector is higher during operation.…”

Section: Discussionmentioning

confidence: 88%

Dynamic distribution of angle kappa and its biomechanical relationships in population who are suitable for excimer laser refractive surgery

W¹,

Cui²,

Li³

et al. 2020

Preprint

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Background To explore the dynamic distribution of pupil size and center,the eccentricity distribution of angle kappa, and its correlation with other biomechanics about suitable for excimer laser refractive surgery. Methods Randomly selected 225 patients (407 eyes) who underwent femtosecond laser combined with excimer laser in situkeratomileusis,preoperative use of Wavelight Allegro Topolyzer Corneal Topography ( Wavelight Laser Technologies AG, Erlangen, Germany ) to measure the pupil size and center position, the German Wavelight EX500 excimer Laser (500Hz) records the deviation between the pupil center and the coaxially sighted corneal light reflex when the patient is supine. Results The average displacement distribution of P-Dist (the eccentricity between the pupil center and the coaxially sighted corneal light reflex point) is 0.225 ± 0.102 mm, and 80% of the eyes are ≤ 0.30 mm.The coaxially sighted corneal light reflex point is mainly deviated to the superior temporal side of the corneal center (34%).Under the dark light condition, the x-axis of the left eye was: -0.046 ± 0.091 mm, the x-axis of the right eye was: -0.152 ± 0.084 mm, with statistical difference ( P = 0.015) (the right eye shifted to the temporal side), the y-axis direction had no statistical change ( P = 0.062). The WTW was positively correlated with changes of pupil diameter (dark pupil diameter-bright pupil diameter) ( r = 0.270, P <0.001).The SE and measured centroid shift was negative correlated ( r = - 0.214, P = 0.002). Conclusion The pupil of the left eye becomes smaller, the anterior chamber becomes shallower, and the angle kappa increases relative to the right eye.In patients with large WTW, a darker light environment is maintained during the operation to improve the efficiency of pupil matching.The dynamic change of angle kappa in high myopia population is small.

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Section: Discussionmentioning

confidence: 88%

Dynamic distribution of angle kappa and its biomechanical relationships in population who are suitable for excimer laser refractive surgery

W¹,

Cui²,

Li³

et al. 2020

Preprint

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“…[ 3 ] The range may slightly differ (4.97 ± 1.24°) if measured with the Orbscan IIz (Bausch and Lomb, USA). [ 10 ]…”

Section: Methodsmentioning

confidence: 99%

Angle Kappa and its importance in refractive surgery

Moshirfar¹,

Hoggan

Muthappan³

2013

Oman J Ophthalmol

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Angle kappa is the difference between the pupillary and visual axis. This measurement is of paramount consideration in refractive surgery, as proper centration is required for optimal results. Angle kappa may contribute to MFIOL decentration and its resultant photic phenomena. Adjusting placement of MFIOLs for angle kappa is not supported by the literature but is likely to help reduce glare and haloes. Centering LASIK in angle kappa patients over the corneal light reflex is safe, efficacious, and recommended. Centering in-between the corneal reflex and the entrance pupil is also safe and efficacious. The literature regarding PRK in patients with an angle kappa is sparse but centering on the corneal reflex is assumed to be similar to centering LASIK on the corneal reflex. Thus, centration of MFIOLs, LASIK, and PRK should be focused on the corneal reflex for patients with a large angle kappa. More research is needed to guide surgeons’ approach to angle kappa.

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“…The kappa angle is generated by the intersection of the visual axis and the pupillary axis in the pupillary space. If the light re ex is in the nasal side, it is classi ed as positive; if it is in the temporal side, it is classi ed as negative [1][2][3]. The line perpendicular to the center of the corneal curvature at the entrance of the pupil is the pupillary axis, and the line joining the xation point and the fovea is the visual axis [3].…”

Section: Introductionmentioning

confidence: 99%

Pupil barycenter configuration in patients with myopia and hyperopia

Koç¹,

Kaya²

2021

Preprint

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Purpose To compare the pupil barycenter configurations that can be used to calculate the kappa angle in terms of distance in patients with myopia and hyperopia. Method : This prospective study evaluated 394 eyes of 197 patients. The patients were divided into two groups according to their spherical equivalent values: the myopic group (mean spherical equivalent refraction < − 0.50 D) and the hyperopia group (mean spherical equivalent refraction > + 0.50 D). The two groups were further subdivided according to severity (myopic group: mild, <−0.50 and ≤ − 3.00 D; moderate, <−3.00 and ≤ − 6.00 D; severe, <−6.00 D; hyperopic group: mild, ≥+0.50 and ≤ + 2.00 D; moderate, >+2.00 and ≤ + 4.00 D; severe, >+4.00 D). The pupil and iris barycenter distance measurements and other parameters were obtained through optical low-coherence reflectometry. Results Of the 197 patients, 109 (55.3%) were female and 88 (44.7%) were male, and their age ranged from 7 to 60 years (mean, 35.16 ± 14.75 years). The average pupil barycenter measurements originating from the kappa angle distances were 0.38 ± 0.15 and 0.21 ± 0.11 mm in patients with hyperopia and myopia, respectively. Corneal and lens thickness measurements were higher in patients with hyperopia, whereas anterior chamber depth and pupil diameter measurements were higher in patients with myopia. No significant difference in astigmatism or white-to-white measurements was observed between patients with hyperopia and those with myopia. Conclusion The kappa angle distances are higher in hyperopia than in myopia. The pupil barycenter measurement from the kappa angle distance can be an alternative for the evaluation of the kappa angle.

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Angle kappa changes after photorefractive keratectomy for myopia

Cited by 17 publications

References 13 publications

Dynamic distribution of angle kappa and its biomechanical relationships in population who are suitable for excimer laser refractive surgery

Dynamic distribution of angle kappa and its biomechanical relationships in population who are suitable for excimer laser refractive surgery

Angle Kappa and its importance in refractive surgery

Pupil barycenter configuration in patients with myopia and hyperopia

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