The Effect Of Angles Kappa And Alpha On Visual Outcomes After Implantation Of Isofocal Intraocular Lenses

This study aims to assess the impact of angle alpha and angle kappa on visual acuity and the objective optical quality following the implantation of an isofocal intraocular lens (IOL) during cataract surgery.

Randomized consecutive study performed at Watani Eye Hospital

This study was conducted on patients with grade N1-3 cataracts (LOCS III) who received an Isopure 123 IOL (Beaver-Visitec International). Exclusion criteria included ocular comorbidities such as diabetic retinopathies, pseudoexfoliation syndrome, glaucoma, corneal opacities, irregular corneal astigmatism, and corneal astigmatism exceeding one Diopter. Evaluated postoperative parameters were UDVA, CDVA, and DCIVA, along with angle kappa, angle alpha, MTF, total HOAs, spherical aberration, coma, and trefoil, using a ray-tracing aberrometer. Measurements were taken at least three months after surgery.

A total of 66 eyes from 33 patients were included. The mean postoperative spherical equivalent was -0.21 ± 0.27 D, with the majority (93.94%) falling within ±0.50 D. Over 95% of eyes achieved 20/25 or better in UDVA and CDVA. Also, 83% achieved 20/40 or better in UIVA, and 94% in DCIVA. The mean total RMS of HOAs, spherical aberration, coma, and trefoil were 0.23±0.08, -0.05±0.07, 0.12±0.03, and 0.07±0.03, respectively. Mean angles kappa and alpha were 0.39±0.14 and 0.45±0.15, respectively. No significant correlation was found between CDVA or DCIVA and HOAs, nor between CDVA or DCIVA and angles alpha or kappa. Even eyes with kappa and alpha angles as large as 0.74mm demonstrated similar visual outcomes to those with smaller angles.

The visual outcomes with the new isofocal IOL, which features an enhanced depth of focus, appear to be independent of angles alpha and kappa up to a cord length of 0.7mm. Nonetheless, these findings should be interpreted with caution, and further studies with a larger sample size may yield different insights.