Predictive factor and kappa angle analysis for visual satisfactions in patients with multifocal IOL implantation

Abstract

Purpose To evaluate the visual acuity and quality-related satisfaction of patients implanted with a refractive design multifocal intraocular lens (IOL), and evaluate the factors predicting it including angle kappa. Setting Dr Agarwal's Eye Hospital and Eye Research Centre, Chennai. Methods In this prospective trial, 50 eyes of 44 consecutive patients were included. All patients underwent phacoemulsification with multifocal IOL implantation (Rezoom IOL, Abbott Medical Optics). The preoperative and postoperative assessment included slit lamp biomicroscopy, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and kappa angle assessment. At 1 year, 37 patients (43 eyes), who finished follow-up, were asked to rate their symptoms on a graded questionnaire (0-5 for five queries). Results The decimal scores for UCVA and BCVA were 0.38 ± 0.21 and 0.47 ± 0.17 (preoperative), and 0.75 ± 0.22 and 0.99 ± 0.11 (postoperative), respectively. Symptom scores were haloes 0.98 ± 1.7, glare 0.69 ± 1.48, blurred distance 1.0 ± 1.7, intermediate 1.34 ± 1.6, near 1.06±1.8. On regression analysis haloes depended on angle kappa and distance UCVA (R 2 ¼ 0.26, P ¼ 0.029), and glare on angle kappa (R 2 ¼ 0.26, P ¼ 0.033). Poor satisfactions with distance, intermediate, and near vision were linked with distance UCVA (R 2 ¼ 0.17, P ¼ 2.3 Â 10 À4 ), distance UCVA (R 2 ¼ 0.1, P ¼ 0.04), and near UCVA (R 2 ¼ 0.12, P ¼ 0.03), respectively. The strongest predictor, however, for overall visual discomfort was distance UCVA (R 2 ¼ 0.1, P ¼ 0.04).Conclusions Our study suggests that there may be a role of misalignment between the visual and pupillary axis (angle kappa) in the occurrence of photic phenomenon after refractive multifocal IOL implantation.

The importance of angle kappa evaluation for implantation of diffractive multifocal intra‐ocular lenses using pseudophakic eye model

“…In the practice, different methods for compensating for a large angle kappa (decentration of the MIOL towards the visual axis) have been described (Melki & HarissiDagher 2011). However, due to memory of the haptics, contraction of the capsule, and IOL rotation, it is uncertain whether the lens would stay in the decentred position (Prakash et al 2011). Conversely, the opposite decentration causes a decrease of the j c and can heighten the risk of photic phenomena.…”

“…The principal limitation is the simplifying presumption that photic phenomena are induced by the interaction of the central ray (corresponding to the nodal axis in our model) with the first MIOL ring. This approach, also considered in another study (Prakash et al 2011), enables to derive a relation between the critical angle kappa and other parameters of the eye and MIOL based on geometrical optics and the thin MIOL approximation (see above), but does not take into account other optical effects caused by diffraction, etc. Thus, this approach does not allow a detailed analysis of the influence of the angle kappa on the photic phenomena, and the real values of the critical angle kappa can differ from our results based on simplified computations.…”

“…By contrast, nasal decentration (in cases of a positive angle kappa) did not cause pronounced photic phenomena. Prakash et al (2011) evaluated the role of angle kappa in the occurrence of photic phenomena after MIOL implantation (Rezoom). They reported that patient complaints about glare and halo showed positive correlation with the preoperative values of angle kappa.…”

“…It is assumed that, in patients with a higher angle kappa, a MIOL may induce more aberrations, glare and halo. To date, only few studies in larger cohorts of patients have been published concerning this problem (De Vries et al 2011;Prakash et al 2011;Karhanov a et al 2013). Although Prakash et al (2011) found a statistically significant association between the angle kappa and photic phenomena, they also noted that many patients with a high angle kappa were asymptomatic.…”

Positioning patients who cannot lie flat

“…Such trends have been shown and explained. [2][3][4] The previous articles also provide equations that explain the tendencies in postsurgical corneal asphericity shown by Bottos et al and the fact that the greater the initial degree of ametropia, the greater the asphericity changes.…”