Stereopsis in bilaterally multifocal pseudophakic patients

Stereopsis Following Implantation of Presbyopia-Correcting Intraocular Lenses: A Narrative Review

Recent advancements in cataract surgery have broadened its scope from mere vision restoration to include correction of refractive errors and presbyopia. This evolution has introduced multifocal and extended depth-of-focus (EDOF) intraocular lenses (IOLs), allowing enhanced vision across multiple distances. However, the influence of these advanced IOLs on stereopsis remains controversial. Factors influencing stereopsis after surgery include visual acuity, interocular differences, residual astigmatism, and the type of IOL, etc. Binocular vision integration and neuroadaptation further affect stereopsis, especially in cases of presbyopia-correcting IOLs. It is widely acknowledged that bilateral implantation of presbyopia-correcting IOLs yield superior stereopsis compared to unilateral implantation. However, there remains no consensus on whether binocular implantation of multifocal or monofocal IOLs provides superior stereopsis. Most studies suggest no significant difference in stereopsis between these two types of implants. Among different types of multifocal IOLs, refractive multifocal IOLs may offer better stereopsis than diffractive multifocal IOLs when implanted bilaterally. Emerging EDOF and hybrid multifocal-EDOF IOLs also demonstrate promising postoperative stereopsis. Additionally, a mix-and-match strategy with different types of IOLs implanted in each eye may result in interocular differences in visual acuity at certain distances, potentially affecting stereopsis. Nevertheless, with appropriate selection, most patients can achieve satisfactory postoperative stereopsis. This review synthesizes current literature on the effects of presbyopia-correcting IOLs on postoperative stereopsis recovery following cataract surgery. Studies on stereopsis outcomes with different IOLs have yielded mixed results, urging further investigation for optimized surgical strategies and patient outcomes.

Stereoacuity and Aniseikonia: Evaluation Before and After Bilateral Implantation of Three Types of Presbyopia-Correcting Intraocular Lenses in Uncomplicated Phacoemulsification with Due Consideration of Interocular Differences in Higher Order Aberrations, Axial Lengths, Refractive Errors, and Acuities

Purpose

To determine if the changes in stereoacuity and aniseikonia, following bilateral implantation of presbyopia correcting intraocular lenses could be predicted from preoperative measurements of higher order aberrations (HOAs), axial lengths (AL), refractive errors (RE) and corrected visual acuities (CVAs).

Patients and Methods

Stereoacuity (Randot tests, @6m & 40cm, in steps of 20 arcsecs") vertical and horizontal aniseikonia (Awaya test @6m, in steps of 1%) with best correction and HOAs (Shack-Hartmann aberrometer) were measured before, 3 and 6 months after uncomplicated bilateral phacoemulsification. Twenty patients (I) underwent a mix-and-match procedure (Tecnis MF, ZKB00 in one eye and ZLB00 in the other), 17 (II) were implanted with a trifocal (AT LISA 839 triMP) and 18 (III) with a one-piece diffractive (Synergy OU) intraocular lens. The resultant aniseikonia (AR) of vertical and horizontal pairs of aniseikonia measurements was calculated using the Pythagorean theorem. Twenty untreated age/gender matched cases were recruited as controls (IV).

Results

The key results (p < 0.001) were a) stereoacuity at distance (SAD) and near (SAN) improved, AR reduced in groups I, II & III remaining unchanged in group IV; b) some significant intergroup differences in SAD, SAN & AR were detected at postop; c) at 6 months postop, changes (Δ=pre- minus postoperative value) correlated with preoperative values (x). Linear regression revealed, I ΔSAD=0.66x-57.47 [0.832, ±66.4], ΔSAN=0.96x-34.59 [0.821, ±16.9], ΔAR=0.93AR-2.12 [0.795, ±1.4] II ΔSAD=0.79x-62.91 [0.916, ±38.1], ΔSAN=0.96x-31.49 [0.892, ±8.0], ΔAR=0.91AR-0.91 [0.839, ±1.3] III ΔSAD=0.67x-35.50 [0.991, ±23.7], ΔSAN=0.88x-38.51[0.988, ±10.6], ΔAR=0.86AR-0.96 [0.900, ±1.3]. Figures in parentheses are the corresponding rs and ±limits of agreement between actual and estimated values. Definitive overarching associations connecting interocular differences in HOAs, AL, RE, and CVAs with SAD, SAN and AR were not found.

Conclusion

Changes in stereoacuity and aniseikonia can be predicted using preoperative values. ΔSAN can be predicted within ±1, and ΔAR within ±2, scale divisions. In group III ΔSAD can be predicted within ±1, and in group I ±3, scale divisions.

Stereopsis after bilateral implantation of Toric intraocular lenses in high myopic cataract patients with astigmatism

Purpose

To evaluate near, intermediate, distance visual acuity and stereopsis after bilateral implantation of Toric intraocular lenses (IOLs) in high myopic patients with astigmatism.

Methods

Bilateral Toric or non-Toric IOL implantation (n ​= ​40 eyes each) was performed on high myopic cataract eyes with astigmatism. Best-corrected distance visual acuity (BCDVA), uncorrected intermediate visual acuity (UCIVA), uncorrected near visual acuity (UCNVA), residual refractive astigmatism (RRA), and near, intermediate, and distance stereoacuity were measured postoperatively at 7 days, 1 month, and 3 months.

Results

The three-month postoperative BCDVA, UCIVA, and UCNVA of the Toric group were 0.08 ​± ​0.07, 0.30 ​± ​0.11, and 0.23 ​± ​0.14 LogMAR. All improved over the preoperative assessments (P ​< ​0.05). The RRA, UCIVA, and UCNVA were significantly better in the Toric group than the non-Toric group at all follow-up examinations (all P ​< ​0.05). At 3 months, the median near and intermediate stereoacuity of the Toric group were 100 (range 40 - 400) and 120 (range 50 - 400) arcsec, which were better than the non-Toric group (both P ​< ​0.05). Fine near stereopsis ≥100 arcsec was present in 65% of the Toric patients, and 50% had good intermediate stereopsis of ≥100 arcsec. However among non-Toric patients, only 15% and 5% achieved fine near and intermediate stereopsis. The postoperative BCDVA and best-corrected distance stereoacuity were similar in the two groups (P ​> ​0.05).

Conclusions

In bilateral high myopic cataract patients with astigmatism, Toric IOLs not only improved UCIVA, UCNVA, and RRA, but also enhanced near and intermediate stereopsis acuity.

Stereoacuity and Multifocal Intraocular Lenses - a Systematic Review

Background

Among various visual functions, stereoacuity, or the ability to perceive depth, is the most sophisticated binocular function. Many publications discuss the influence of retinal image formation by multifocal intraocular lenses on glare and contrast sensitivity, but only a few present results of testing binocular vision in patients with multifocal intraocular lenses.

Objective

This article is designed to review the results of testing binocular vision in patients with multifocal intraocular lenses implanted in cataract surgery.

Methods

This article was performed based on a literature review and Internet search through scientific databases such as PubMed, Scopus, Web of Science, and Google Scholar.

Results

Some reports found that patients implanted with the monofocal lens, when measured with a near addition, presented statistically significant better stereoacuity scores than those implanted with any of the multifocal intraocular lens types. When the TNO test was used for measurement, statistically significant better stereoacuity was disclosed with the refractive multifocal intraocular lens than with the diffractive-based multifocal intraocular lens design. Stereoacuity scores, even within the same types of lenses, were significantly better with the Titmus test than with the TNO test.

Conclusion

Stereoacuity is not affected by multifocality-induced retinal blur as it is by other causes of image degradation such as small residual refractive error very early opacification of ocular media or dry eye. Multifocal intraocular lenses do not cause more functional aniseikonia than would be expected with a monofocal intraocular lens. Since stereoacuity is compromised with unilateral multifocal intraocular lens implantation bilateral implantation should be attempted.

Stereopsis and visual acuity: Bilateral trifocal versus blended extended depth of focus and diffractive bifocal intraocular lenses

PURPOSE

To compare stereopsis and visual acuity (VA) between bilateral implantation of trifocal intraocular lenses (IOL) and blended implantation of an extended depth of focus (EDOF) IOL with a bifocal IOL.

METHODS

This is a non-randomized, prospective comparative study included 74 eyes of 37 patients who underwent phacoemulsification and bilateral implantation of AT LISA tri 839MP IOL (bilateral group; 21 patients) or blended implantation of Tecnis Symfony ZXR00 and Tecnis ZLB00 IOL (blended group; 16 patients). The primary outcomes were stereoacuity and binocular VA. The secondary outcomes were visual defocus curve, quality of life, and patient satisfaction. Follow-up was performed 3 months after the surgery.

RESULTS

The mean near stereoacuity was 49.76 ± 22.67 and 120.63 ± 90.94 seconds of arc (arcsec) in the bilateral and blended groups, respectively (P < 0.001). Near stereoacuity was positively correlated with VA difference of two eyes (r = 0.896, P < 0.001). The mean binocular uncorrected visual acuity at 40 cm, 80 cm, 5 m, and corrected distance visual acuity at 5 m of the bilateral and blended groups was not statistically significant different. The bilateral group had better VA at a vergence from -2.5 to -4.0 D. Both groups obtained high quality of life and patient satisfaction scores.

CONCLUSION

The bilateral and blended groups achieved good binocular VA, quality of life, and high patient satisfaction. However, the near stereoacuity of the blended group was worse.

Comparison of trifocal toric and bifocal toric intraocular lens implantation in patients with cataract and high corneal astigmatism

AIM

To investigate and compare the quality of life, satisfaction, contrast sensitivity, glare, depth perception, and intraocular lens (IOL) rotation in patients who underwent trifocal toric and bifocal toric IOLs.

METHODS

A total of 80 eyes of 40 patients were included in this prospective study. Twenty patients in each group were implanted with trifocal toric and bifocal toric IOL, respectively. Preoperative and postoperative 6-month measurements were recorded for both patient groups. Comprehensive anterior and posterior segment examinations, distance-intermediate-near visual acuity values and the visual function scale questionnaire results were evaluated at these examinations. Patient satisfaction, contrast sensitivity, glare, intermediate-near and distance stereopsis and IOL rotation were also evaluated.

RESULTS

No significant difference was found between the groups in terms of distance and near visual acuities (P=0.269, P=0.451). Intermediate visual acuity was significantly increased in the trifocal toric group (P<0.001). The visual function scale results were increased after surgery in both groups (P=0.001 and P<0.001), with no difference determined between them (P=0.158 and P=0.691). The number of patients wearing glasses was low in both groups and there was no significant difference between the groups (P>0.05). The overall satisfaction in the trifocal toric group was significantly higher than in the bifocal toric group (P=0.03). The highest sensitivity was observed at 6 cpd spatial frequency in all patients under photopic conditions (1.80±0.24 logU, 1.74±0.20 logU). Distance-intermediate-near binocular depth perception results in both groups were higher in the trifocal toric group (P=0.02, 0.048, 0.003, respectively). Although there was no significant difference for 3 meters stereopsis, the trifocal toric group had higher depth perception (P=0.577). Mean rotation was 5.76°±3.93° in the trifocal toric group and 12°±7.1° in the bifocal toric group.

CONCLUSION

Better results in the middle distance are obtained in the trifocal toric group and less IOL rotation due to digital system-coordinated surgery. Moreover, the overall satisfaction in the trifocal toric group is significantly higher than in the bifocal toric group.

Monovision with a Bifocal Diffractive Multifocal Intraocular Lens in Presbyopic Patients: A Prospective, Observational Case Series

PURPOSE

We report the visual outcomes and patient satisfaction after bilateral implantation of a bifocal diffractive intraocular lens with monovision.

DESIGN

Prospective, observational case series.

METHODS

Twenty-one subjects underwent cataract surgery or refractive lens exchange with bilateral implantation of the ZMB00 intraocular lens, with the dominant eye and nondominant eye targeted for plano and -1.25 to -1.00 diopters, respectively. Postoperative assessments included visual acuity (VA) at various distances under photopic and mesopic conditions; defocus curve, contrast sensitivity, and stereopsis; and Visual Function Questionnaire-25 and supplementary questionnaire.

RESULTS

Mean binocular uncorrected VA at distance, intermediate (67 cm), and near (30 cm) were -0.03 ± 0.06, 0.12 ± 0.18, and 0.11 ± 0.05, respectively. No eyes lost >1 line of corrected distance VA. Binocular intermediate VA was significantly better in the uncorrected condition (P = .004) whereas binocular distance VA was better in the distance-corrected condition (P = .014). Near VA was similar in both conditions (P > .05). Stereoacuity and contrast sensitivity were within normal limits. All subjects had a composite score of ≥90 for vision-targeted items in the National Eye Institute Visual Function Questionnaire-25. Halos, glare, and starbursts occurred in 52%, 29%, and 24% of subjects, respectively. All subjects reported a satisfaction score of ≥3.5 of 5 and required no spectacles postoperatively. No intraocular lens exchange was required.

CONCLUSIONS

Monovision with bilateral bifocal multifocal intraocular lens was safe and provided satisfactory vision at various distances, with good stereopsis and contrast sensitivity. Complete spectacle independence and high satisfaction score were achieved. In comparison with bilateral emmetropic bifocal multifocal intraocular lens, it provided better vision at intermediate and at very near distances without inducing more dysphotopsia.

Optimal near and distance stereoacuity after binocular implantation of extended range of vision intraocular lenses

PURPOSE

To evaluate stereopsis and visual quality after bilateral implantation of extended range of vision intraocular lenses (ERV IOLs).

SETTING

R.P. Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.

DESIGN

Prospective interventional study.

METHODS

Patients underwent phacoemulsification with bilateral implantation of ERV IOLs. The primary outcome measures were stereopsis (distance and near Randot) and visual quality (ray-tracing aberrometry). The secondary outcome measures were visual acuity and patient satisfaction. Follow-up was performed on day 1 and at 1, 3, 6, and 12 months postoperatively.

RESULTS

The study comprised 50 patients (100 eyes). The mean age of the patients was 58.9 years ± 8.9 (SD). At 1 year, the mean distance stereopsis was 103.6 ± 49.1 seconds of arc (arcsec) and near stereopsis was 21.1 ± 2.3 arcsec. Perfect near stereopsis of 20 arcsec was present in 80% of cases, and 82% had good distance stereopsis of 100 arcsec or better. Stereopsis correlated well with the patient satisfaction score (P < .001) and average internal modulation transfer function (MTF) (P < .015). The mean Strehl ratio was 0.029 ± 0.021, MTF was 0.24 ± 0.08, total higher-order aberrations were 0.62 ± 0.41 μm, and coma was 0.25 ± 0.18 μm. The mean binocular uncorrected decimal visual acuities were 0.98 ± 0.07 (distance), 0.82 ± 0.09 (intermediate) and 0.64 ± 0.08 (near). The mean patient satisfaction score was 9.08 ± 1.1, and no case required IOL explantation because of visually disturbing phenomena or patient dissatisfaction.

CONCLUSION

Excellent stereoacuity was observed after bilateral implantation of ERV IOLs, which correlated well with patient satisfaction and quality of vision.

Stereo-acuity in patients implanted with multifocal intraocular lenses: is the choice of stereotest relevant?

PURPOSE

A randomized and double-blinded study design was implemented to assess the stereo-acuity in patients symmetrically implanted with four types of multifocal intraocular lenses (MIOLs), compared to a monofocal lens (control group). In addition, the influence of the type of test employed for the evaluation of stereo-acuity was explored.

MATERIALS AND METHODS

Six months after cataract intervention, stereo-acuity was measured with the Titmus and TNO stereotests in 143 patients implanted with one of the following MIOL lens types: hybrid spherical SN60D3, hybrid aspheric SN6AD1, diffractive aspheric ZMA00 and refractive spherical NXG1. A control group implanted with the monofocal aspheric ZA9003 (in which stereo-acuity was measured with a near addition) was also included in the study.

RESULTS

Statistically significant better stereo-acuity was found in the monofocal group with both stereotests (except for the SN60D3 group with the Titmus test) (all p < 0.001). No significant differences in stereo-acuity between MIOLs were found using the Titmus test. However, with the TNO, patients implanted with hybrid diffractive MIOLs exhibited statistically significant worse stereo-acuity than those with the refractive design (SN60D3, p < 0.001; SN6AD1, p = 0.006).

CONCLUSIONS

Patients implanted with MIOLs have worse stereo-acuity than those implanted with monofocal IOLs due to the decrease in retinal image contrast originating in the simultaneous presence of two images. A wavelength-based stereotest such as the TNO induces large differences in image contrast between fellow eyes implanted with diffractive-based MIOLs, which may result in an underestimation of the real stereo-acuity of the patient.

Laterality does not affect the depth perception, but interpupillary distance

In this study, which investigates the relationship between the levels of stereopsis with eye and hand dominance or interpupillary distance, 120 healthy young volunteers were investigated. Eye dominance was determined by modified Miles technique following a complete eye examination. Handedness was assessed with the Edinburgh handedness inventory. Interpupillary distance was measured with millimetric ruler. Stereoacuity was measured in both contour (Titmus test) and random dot (TNO test) stereograms. The stereopsis scores were evaluated in terms of hand or eye dominance. The correlation between stereopsis score and interpupillary distance was assessed. Main outcome measures were stereopsis scores according to hand and eye dominance. As a result, right- and left-handed individuals showed no differences in terms of stereopsis. No differences were found in stereopsis scores between right- and left-eye dominant people. There was a correlation between interpupillary distance and the depth of stereopsis (r = −0.248, P < 0.05). Contrary to the expectation, the left and right dominant individuals did not differ in levels of stereopsis. Interpupillary distance has a positive effect on stereopsis.

Visual performance comparison between contact lens-based pinhole and simultaneous vision contact lenses

BACKGROUND

The aim was to evaluate the visual performance provided with a contact lens-based pinhole design against a simultaneous vision multifocal contact lens.

METHODS

In a cross-over study at the University of Valencia, 22 presbyopic patients were evaluated using an artificial pupil fitted on the non-dominant eye and the simultaneous vision PureVision Multifocal contact lenses. After one month of contact lens wear, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85 cd/m(2)). In addition, binocular distance visual acuity and binocular distance contrast sensitivity were examined under mesopic conditions (5 cd/m(2)).

RESULTS

Mean binocular distance visual acuity for pinhole and PureVision Multifocal were 0.02 ± 0.04 and 0.01 ± 0.04 logMAR under photopic conditions and 0.16 ± 0.06 and 0.12 ± 0.04 logMAR for binocular near visual acuity under mesopic conditions, respectively. No statistically significant differences were found between both types of lenses at distance for both lighting levels and intermediate distances (p > 0.05). There was a significant difference at near vision under photopic conditions (p = 0.03). Binocular distance contrast sensitivity revealed statistically significant differences between the pinhole system and PureVision Multifocal for six and 12 cpd (cycles per degree) spatial frequencies at the two luminance levels, while for near vision, differences were also significant for 18 cpd. Stereoacuity was better with PureVision Multifocal (127 ± 49.3 seconds of arc) compared with the pinhole lens (220.2 ± 32.3 seconds of arc, p = 0.004).

CONCLUSION

Pinhole and PureVision Multifocal contact lenses provide good binocular vision for distance and functional intermediate vision. Although it was better with the PureVision Multifocal, near vision was not satisfactory for either of the two contact lens options.

Visual and refractive outcomes after implantation of a fully diffractive trifocal lens

Background

The purpose of this study was to record the visual outcomes of patients treated by six surgeons after implantation of a trifocal lens.

Methods

The setting for this study comprised six ophthalmology units and eye clinics in Belgium and France, with a coordinating center in France, and data management and statistical analysis in France and Belgium. Ninety-four eyes from 47 patients were implanted with a trifocal FineVision^® intraocular lens by six surgeons. Monocular and binocular, uncorrected and best distance-corrected, and photopic and mesopic visual acuity was measured, as well as the defocus curve between +4 D and −4 D with best distance correction.

Results

Near and far monocular visual acuities were similar to the data published after bifocal intraocular lens implantation. Intermediate vision was improved, and was demonstrated by scores of near visual acuity as well as far visual acuity with defocus −1.5 D-add lens. Far vision is maintained in mesopic conditions.

Conclusion

The trifocal intraocular lens provides good far, intermediate, and near visual acuity.

Visual comparison of an artificial pupil contact lens to monovision

PURPOSE

To assess and compare the effects of contact-lens based artificial pupil design and monovision correction on visual performance.

METHODS

In a cross-over study design, 22 presbyopic patients (age range 50 to 64 years) were evaluated using artificial pupil contact lens on the non-dominant eye and monovision. After 1 month, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85 cd/m2), in each patient after contact lens fitting. Moreover, BDVA and binocular distance contrast sensitivity were examined under mesopic conditions (5 cd/m2).

RESULTS

Average artificial pupil contact lens and monovision BDVA were 0.02 ± 0.04 and 0.00 ± 0.09 logMAR for photopic conditions, and 0.16 ± 0.06 and 0.13 ± 0.12 logMAR for binocular near visual acuity under mesopic conditions, respectively. No statistically significant differences were found between the two types of lenses at distance for both lighting levels (p > 0.05), but there were, however, significant differences at intermediate distances and near vision (p < 0.05). Binocular distance contrast sensitivity revealed statistically significant differences between artificial pupil contact lens and monovision for 1.5 cycles per degree (cpd) under photopic conditions, and 12 and 18 cpd under mesopic conditions (p < 0.05), respectively. Statistically significant differences for all spatial frequencies except for 1.5 cpd were found at near vision (p < 0.05). The mean values of stereoacuity obtained for artificial pupil contact lens (221 ± 32 sec arc) were slightly worse than for monovision correction (210 ± 49 sec arc), and statistically significant differences were not found (p = 0.23).

CONCLUSIONS

Monovision performed better than an artificial pupil contact lens of the same material for near visual acuity and near contrast sensitivity. Only, the artificial pupil contact lens provides better intermediate visual acuity.

Visual function through 4 contact lens-based pinhole systems for presbyopia

PURPOSE

To evaluate the effects of different contact lens-based artificial pupil designs on visual performance.

SETTING

University of Valencia, Burjassot, Spain, and University of Manchester, Manchester, United Kingdom.

DESIGN

Comparative case series.

METHODS

Presbyopic patients were evaluated using 4 artificial pupil designs in the nondominant eye. Binocular uncorrected distance visual acuity (UDVA), binocular corrected distance visual acuity (CDVA), binocular uncorrected near visual acuity (UNVA), binocular distance-corrected near visual acuity (DCNVA), defocus curve, binocular distance, and near contrast sensitivity under photopic and mesopic conditions, and stereoacuity were measured after contact lens fitting.

RESULTS

The mean UDVA and CDVA ranged from 0.04 ± 0.05 (SD) to -0.01 ± 0.04 logMAR and from -0.02 ± 0.05 to -0.05 ± 0.03 logMAR, respectively. The UNVA and DCNVA ranged from 0.37 ± 0.11 to 0.42 ± 0.20 logMAR and from 0.35 ± 0.17 to 0.38 ± 0.12 logMAR, respectively. The difference in binocular distance contrast sensitivity was statistically significant between the pinhole systems and the control group (distance-corrected patients without pinhole lens) for 6 cycles per degree (cpd), 12 cpd, and 18 cpd; for near vision, differences were also significant for 3 cpd at the 2 luminance levels (P<.05). Stereoacuity values for near vision were not significantly different between the 4 pinhole systems (P>.05).

CONCLUSIONS

Soft contact lens apertures provide good visual acuity at distance, functional intermediate vision, and poor near visual acuity and stereoacuity. An improvement in visual performance with decreasing pupil diameter was not found.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.