Use of Presbyopia-Correcting Intraocular Lenses in Patients With Prior Corneal Refractive Surgery

Majid Moshirfar; Andrew C. Thomson; Robert J. Thomson; Tanisha Martheswaran; Shannon E. McCabe

Disclosures

Curr Opin Ophthalmol. 2021;32(1):45-53. 

In This Article

Preoperative Considerations

Many of the same preoperative considerations for eyes with virgin corneas also apply to postkeratorefractive patients. Visual outcomes may be diminished by preexisting intraocular and ocular surface disorders that produce adverse optical phenomena including higher order aberrations (HOAs), light scatter, and dysphotopsias. These diseases may be absolute or relative contraindications to presbyopia-correcting IOL implantation. Therefore, a comprehensive preoperative ophthalmologic evaluation, including subjective and objective measures is recommended.[17]

Dry eye disease (DED), a common postkeratorefractive compilation, meibomian gland dysfunction, and other tear film irregularities increase light scatter and decrease both contrast sensitivity and optical quality after IOL implantation.[18] Preoperative ocular surface assessment should include dry eye symptom evaluations, such as the ASCRS Speed II Questionnaire, slit-lamp examination, and other diagnostic measures. Modern Optical Quality Analysis Systems allow for objective quantification of the modulation transfer function (MTF), objective scatter index (OSI), Strehl ratio, and aberrometry.[19] Recording the dynamic changes in OSI in unblinking patients correlates highly with tear film stability.[20] DED and other tear film abnormalities can cause erroneous IOL calculations and are common sources of patient dissatisfaction,[17] [A]. Therefore, dynamic analysis of tear film integrity constitutes an effective preoperative tool for assessing the ocular surface, even in asymptomatic patients.[18] As a rule, any DED detected on examination warrants aggressive management to improve the accuracy of preoperative IOL calculations and postoperative outcomes.[17] Punctal occlusion with dissolvable or permanent plugs is a safe, effective method for treating DED that should be considered in postkeratorefractive patients prior to and after presbyopia-correction IOL implantation [A].

Ocular Pathology

Corneal abnormalities, such as pterygia and dystrophies, especially Fuch's dystrophy, are contraindications to presbyopia-correcting IOLs, yet well managed, nonprogressive corneal or retinal diseases may not preclude patients from achieving satisfactory outcomes. Ocular coherence tomography, fluorescein angiography, and visual field testing can evaluate subtle or occult retinal and optic nerve disease that could compound the decreased contrast sensitivity associated with MFIOLs.[21] MFIOLs, in particular, should be avoided in patients with progressive retinal disorders because the lens may obscure a retinal surgeon's intraoperative fundal view.[22]

Pupil Diameter

Larger pupils are associated with a higher risk of dysphotopsias secondary to HOAs.[23] In eyes with HOAs, more incorrectly focused peripheral rays begin to enter the eye with pupil dilation causing dysphotopsias. As a rule, for every doubling of the pupil diameter, aberrations increase 16-fold.[24] De Vries et al. found larger pupils of 5.18 mm at low mesopic conditions had more difficulty reading and reported more dissatisfaction with their overall visual outcomes.[23] Asymmetric, irregular pupils also generate dysphotopsias and likely exclude patients from presbyopia-correcting IOLs.[21]

An uneven or decentered capsulorhexis can lead to a decentered IOL resulting in reduced presbyopia-correcting IOL function, particularly for smaller pupils.[10] Ouchi and Shiba found that preoperative photopic pupils less than 3.0 mm had a statistically significant decrease in contrast sensitivity at higher spatial frequencies (12 and 18 cpd) after Tecnis Multifocal (Abbott Medical Optics, Inc.) implantation.[25] However, Fernandez et al. found a statistically insignificant increased performance in contrast sensitivity for pupils less than 3.0 mm with Versario Multifocal (Bausch & Lomb, Rochester, New York, USA) implantation.[26] Of note, both studies examined MFIOLs in virgin corneas. Nonapodized diffractive and nonprogressive refractive MFIOLs are not as dependent on pupil dynamics and may be better suited for patients with smaller pupils.[11,21,23]

Angle Kappa and Alpha

Angle kappa is defined as the angle or distance between the patient's visual axis and pupil center, while the angle alpha describes the difference between the visual axis and limbal center, which correlates to the capsular bag center. Angle kappa is typically larger in hyperopes and smaller in myopes compared with emmetropes.[27] Although angle kappa does not appear to change after myopic refractive surgery,[28] a large angle kappa or alpha may increase the risk of a decentered multifocal IOL, especially temporarily, which may result in poorer objective outcomes such as reduced MTF and Strehl ratio and increased OSI in addition to halos and glare.[10,29,30]

A 2012 study using mechanical eye models found no clinically relevant effects until decentration from the pupil center was greater than 0.75 mm.[10] A 2019 study by Velasco-Barona et al.[31] using the PanOptix MFIOL on 23 eyes found no statistically significant correlation between moderate angle kappa magnitudes (ranging from 0.10 to 0.62 mm) and visual acuities or HOAs. IOL inner optical diameters differ in size between models, and half of that diameter equals the theoretical limit for a particular angle kappa,[29] [B]. Velasco-Barona et al. also compared the effect of IOL inner optical diameters between the PanOptix and AT LISA tri 839 (Carl Zeiss Meditec, Jena, Germany) MFIOLs (1.164 and 1.04 mm, respectively) and found no influence on visual acuities in angle kappas under 0.62 mm. Qi et al., however, found that an angle kappa above 0.4 mm increases the incidence of glare and halos with visual acuity being affected at angles greater than 0.5 mm.[32] Lee et al.[33] also found that in eyes with virgin corneas undergoing PanOptix implantation, higher alpha angles correlated with worse visual outcomes, and lower angles were predictive of better uncorrected near and distance visual acuity. Some surgeons suggest avoiding presbyopia-correcting IOLs in patients with an angle alpha greater than 0.5 mm on ray-tracing devices [C]. It has also been recommended to nudge the IOLs nasally to place it between the visual axis and pupil center [D].

Aberrometry

Preoperative astigmatism of greater than 1.00 D warrants intraprocedural astigmatic keratotomy or a toric IOL, and postoperative refraction should be within 0.50 D of the target with minimal astigmatism or poor optical quality and halos may be induced with presbyopia-correcting IOLs.[34,35] Corneal refractive surgery significantly alters natural corneal aberration. When the photorefractive surgery was performed may also be important, as older ablation techniques tended to employ smaller ablation zones. Larger, transitional ablation zones applied today equate to larger optical zones, which are associated with fewer HOAs and are therefore more likely to be compatible with presbyopia-correcting IOLs.[36] Newer wavefront-guided ablation techniques have also contributed to fewer postoperative HOAs.[24] Preoperative corneal topography should be performed to examine the size and centration of the previous keratorefractive ablation zones. The IC-8 (AcuFocus, Inc., Irving, California, USA), a small aperture EDOF IOL, utilizes the pinhole effect to attenuate the visual symptoms of HOAs, and it has been shown to work well in patients with abnormal corneas such as post-radial keratotomy.[14,37]

Spherical aberrations can be addressed with the IOL asphericity. Generally, for virgin or oblate postmyopic surgery corneas, aspheric IOL implants possessing negative spherical aberrations may be more appropriate to offset the positive spherical aberrations of the cornea.[38,39] Conversely, spherical IOL implants, with positive spherical aberrations, are likely better suited for hyperprolate, posthyperopic refractive surgery corneas.[40] Adequate refractive outcomes have also been achieved with aspheric MFIOLs in posthyperopic surgery eyes.[41] Currently, no guidelines exist regarding the amount of spherical aberrations or other HOAs that precludes the use of presbyopia-correcting IOLs.

Potential HOA thresholds for MFIOL implantation in postrefractive surgery eyes formed from ongoing clinical discussions between peers as well as peer reviewed and nonpeer reviewed publications are listed in Table 2 and displayed as an algorithm in Figure 1. Reports on preoperative HOAs in postkeratorefractive patients undergoing MFIOL implantation are few. A case series by Agarwal et al. reported that cataract patients with prior radial keratotomy had diminished postoperative contrast sensitivity in eyes with more than ±0.20 μm of preoperative coma.[14] In addition, an anterior corneal coma more than ±0.32 μm may cause intolerable dysphotopsias after diffractive MFIOL implantation in virgin corneas.[43,44] According to some surgeons, presbyopia-correcting IOLs appear to cause nighttime defocus and spherical aberrations in patients with more than 1 D of difference between manifest refractions in photopic and mesopic conditions [B].

Figure 1.

Potential decision-making algorithm based on preoperative measures. Data from peer-reviewed studies as well as nonpeer reviewed publications and clinical correspondence among peers [10,14,25,26,32,41,42,C,F]. D, diopter; DED, dry eye disease; EDOF, extended depth of focus; IOL, intraocular lens; MFIOL, multifocal intraocular lens; RK, radial keratotomy; Z3, total 3rd order higher order aberrations; Z4 total 4th order higher order aberrations.

Vrijman et al. found refractive outcomes using aspheric MFIOLs (Acrysof Restor; Alcon Laboratories, Fort Worth, Texas, USA) were comparable with monofocals in patients with postmyopic treatments less than 6 D and posthyperopic treatments less than 4 D, although patient satisfaction and dysphotopsias were not reported.[41,42] Some surgeons avoid multifocals in prior myopic laser-assisted in-situ keratomileusis (LASIK) corrections greater than −4 to −6 D and hyperopic LASIK corrections greater than +2 to +3 D [E]. The capsular bag in high myopes is often larger which may lead to IOL instability and worse visual symptoms.[45] Night vision problems or blurry vision after LASIK may also indicate a decentered ablation potentially making MFIOLs inappropriate. Some surgeons find that EDOFs are better tolerated in patients with residual refractive error making them potential options for post-LASIK patients. [E]. A study by Ruiz-Alcocer et al. using simulated myopic LASIK treatments in patients after EDOF (XACT Mono-EDOF; Santen Pharmaceutical Co., Ltd., Osaka, Japan) and trifocal (FineVision; PhysIOL, Liège, Belgium) IOL implantation, found the EDOF IOL was less affected by poor calculation accuracy and had better optical quality with distance vision compared with the trifocal IOL.[46] Results from Ruiz-Alcocer et al. along with those of two other studies examining AT LISA tri 839 MP in post-LASIK patients also found an average residual refractive error of around −0.50 D from the intended target which may require calculation compensation.[45–47] Based on results from a prospective nonrandomized study using the Tecnis Symfony EDOF IOL in virgin corneas, Fu et al.[30] suggested 'micromonovision' target refractions of −0.35 D in the dominant and −0.50 D in the nondominant eye to maintain good uncorrected distance visual acuity while providing better uncorrected intermediate visual acuity and uncorrected near visual acuity. Another study on Symfony IOLs by Cocherne et al. a target of −0.50 to −0.75 D in the nondominant eye.[48]

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