Binocular vision alterations after refractive and cataract surgery: a review

Full range of vision and visual quality after mini-monovision FS-LASIK in high myopic patients with presbyopia

BACKGROUND

To evaluate clinical outcomes and visual quality 3 months after mini-monovision (spherical equivalent [SE] between - 0.25 D and - 0.50 D) femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for correction of high myopia in patients with presbyopia.

METHODS

Patients who had mini-monovision FS-LASIK for high myopia (SE < -6.0 D) and aged between 40 and 50 years were included. At the 3-month postoperative visit, we evaluated full range of visual acuity; defocus curve; optical quality; accommodation function, contrast sensitivity and stereopsis. Binocular tests were done twice, once in mini-monovision condition and once with the residual myopia in the non-dominant eye corrected. Subjective visual quality was evaluated with questionnaire postoperatively with mini-monovision correction.

RESULTS

Clinical data of 31 cases were analyzed. The average patient age was 42.58 ± 3.06 years. At the 3-month follow-up, the mean uncorrected binocular visual acuity at distance, intermediate, and near was - 0.11 ± 0.07, -0.06 ± 0.10, and 0.04 ± 0.11 logMAR separately. In comparison, patients with binocular full distance correction achieved better uncorrected distance visual acuity (UDVA), and they achieved superior uncorrected near visual acuity (UNVA, P = 0.04) with mini-monovision correction. FS-LASIK induced significant increases in higher-order aberrations (HOAs) (P < 0.001). For accommodative function, only the negative relative accommodation (NRA) improved significantly after surgery (P < 0.001). A slight decrease in contrast sensitivity was observed at low spatial frequency with mini-monovision correction (P < 0.05). Questionnaire demonstrated high satisfaction with near vision and visual quality.

CONCLUSION

FS-LASIK with mini-monovision (SE between - 0.25 D and - 0.50 D) appeared to be safe and effective in treating high myopia combined with presbyopia to get satisfying visual quality at distant and at near.

Evaluation of Early Accommodation Outcomes Following Femtosecond Laser-Assisted in situ Keratomileusis and Small Incision Lenticule Extraction

PURPOSE

The aim of this study is to assess the changes and differences in early postoperative binocular accommodative function following femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE).

METHODS

In this retrospective study, 120 patients (240 eyes) diagnosed with low-to-moderate and high myopia, who underwent either FS-LASIK or SMILE procedures were included. The assessment encompassed measurements of accommodative facility, accommodation time, relaxation time, and accommodation-to-relaxation ratio using a smart flipper. Measurements were taken preoperatively, as well as at 1 day, 1 week, and 1 month postoperatively. Additionally, the visual fatigue scale score was assessed and compared at the 1 month mark post-surgery. Changes in parameters were quantified by calculating the difference between preoperative values and those recorded at each postoperative time point.

RESULTS

At 1 month post-surgery, both FS-LASIK and SMILE procedures demonstrated potential for recovery or even improvement in accommodative facility, accommodation time, relaxation time, and accommodation-to-relaxation ratio compared to preoperative levels. The FS-LASIK group exhibited a greater magnitude of change in accommodative facility postoperatively compared to the SMILE group. In the low-to-moderate myopia subgroup, the FS-LASIK group exhibited lower changes in accommodation time and visual fatigue scale score at 1 month post-surgery compared to the SMILE group, with all associated p-values <0.05.

CONCLUSIONS

Early postoperative recovery of accommodation function was slower following SMILE compared to FS-LASIK. Additionally, the severity of visual fatigue at 1 month post-surgery was greater in the SMILE group than in the FS-LASIK group. This difference in visual fatigue levels may be attributed to the delayed recovery observed in postoperative SMILE procedures.

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.

Comparison of binocular visual quality in six treatment protocols for bilateral cataract surgery with presbyopia correction: a prospective two-center single-blinded cohort study

OBJECTIVE

To compare the postoperative binocular visual quality in six treatment protocols for bilateral age-related cataract surgery with presbyopia correction for clinical decisions.

MATERIALS AND METHODS

In this prospective two-center single-blinded cohort study, participants from North or South China who underwent bilateral phacoemulsification and intraocular lens implantation were divided into six protocols: monovision, diffractive bifocal, mixed, refractive bifocal, trifocal, and micro-monovision extended range of vision (EROV). Binocular visual quality was evaluated at 3 months postoperatively, including binocular uncorrected full-range visual acuity, binocular defocus curves (depth of focus [DoF] and area under the curve [AUC]), binocular visual function (fusion function and stereopsis), binocular subjective spectacle independence rates, visual analog scale (VAS) of overall satisfaction, 25-item visual function questionnaire (VFQ-25), and binocular dysphotopsia symptoms.

RESULTS

Of the 300 enrolled patients, 272 (90.7%; 544 eyes) were analyzed. The trifocal protocol showed excellent binocular full-range visual acuity and the best performance for most DoFs and AUCs. The monovision protocol presented the worst binocular visual quality in most perspectives, especially in convergence, distance, and near stereopsis (p < 0.001). The full-range subjective spectacle independence rates were sorted from highest to lowest as follows: trifocal (84.8%), refractive bifocal (80.9%), EROV (80.0%), mixed (73.3%), diffractive bifocal (65.2%), and monovision (32.6%) protocols, with no statistically significant differences between the former five protocols (p > 0.05). The EROV protocol achieved the highest VAS and VFQ-25 scores. The incidence of postoperative binocular dysphotopsia symptoms was comparable in all protocols.

CONCLUSIONS

The trifocal protocol showed the best performance, and the monovision protocol presented the worst performance in most perspectives of binocular visual quality for presbyopia correction. The refractive bifocal, mixed, or EROV protocols can provide an approximate performance as a trifocal protocol. Ophthalmologists can customize therapies using different protocols.

Are binocular alignment and convergence amplitude different between phakic and pseudophakic older patients?

PURPOSE

To compare the binocular alignment status and convergence amplitude between phakic and pseudophakic older adults.

METHODS

The present report is a part of the Tehran Geriatric Eye Study (TGES), a population-based study performed on the elderly population above 60 years of age in Tehran, Iran. All study participants were transferred to the examination site and underwent complete ocular examinations including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, unilateral and alternating cover tests, and slit-lamp biomicroscopy.

RESULTS

Of 3791 invitees, 3310 participated in the TGES (response rate: 87.3%). After applying the exclusion criteria, the data of 1969 individuals were analyzed for this report. The mean of far exophoria, far esophoria, near exophoria, and near esophoria was 5.09 ± 3.66, 8.20 ± 9.60, 6.94 ± 3.69, 7.00 ± 5.83 prism diopter in phakic and 5.15 ± 2.43, 6.50 ± 5.80, 7.77 ± 4.00, 4.75 ± 1.50 prism diopter in pseudophakic individuals, respectively. The mean of far exotropia, far esotropia, near exotropia, and near esotropia was 14.92 ± 9.49, 22.00 ± 13.86, 15.09 ± 7.20, 21.33 ± 14.47 prism diopter in phakic and 19.67 ± 22.5, 8.00 ± 0, 17.36 ± 7.55, 17.36 ± 7.55, 0 prism diopter in pseudophakic individuals, respectively. Near exophoria (P = .003) was significantly higher in pseudophakic than in phakic participants after controlling the effects of age, sex, body mass index, diabetes, and hypertension. The mean near point of convergence was 7.94 ± 3.27 cm in phakic and 7.99 ± 3.3 cm in pseudophakic participants.

CONCLUSION

Near exophoria was significantly higher in pseudophakic compared to phakic individuals while other deviations and near point of convergence were not significantly different between phakic and pseudophakic groups.

Cataract surgery is not associated with post-operative binocular vision anomalies in age-related cataract patients

PURPOSE

To compare the binocular vision status of patients pre- and post-cataract surgery, and to investigate the risk factors for patients who develop binocular vision anomalies post-surgery.

METHODS

A prospective study of patients (≥50 years) who elected to undergo bilateral cataract surgery was implemented. A comprehensive binocular vision test battery including stereopsis, ocular alignment, fusional vergence, vergence facility, near point of convergence and the Convergence Insufficiency Symptom Survey (CISS) was administered before the first surgery and at the third visit after surgery on the second eye. A detailed diagnostic classification protocol was applied to identify the presence of binocular vision anomalies pre- and post-surgery.

RESULTS

Seventy-three participants were included at baseline, 24 (33%) of whom were diagnosed with non-strabismic binocular vision anomalies (NSBVA), mainly convergence insufficiency (18/73, 25%). Fifty-one participants completed the post-operative evaluation, 17 (33%) of whom had NSBVA pre-surgery and 13 (26%) post-surgery (p = 0.48). There were a number of conversions from NSBVA to normal binocular vision and vice versa. Logistic regression showed that the adjusted odds ratio of pre-existing NSBVA diagnosis for predicting the risk of post-operative NSBVA was 6.37 (p < 0.01). There were no significant changes in most binocular vision measures post-surgery, except for a significant improvement in the CISS score (p < 0.01, Cohen's d = 0.83).

CONCLUSIONS

Binocular vision anomalies, especially convergence insufficiency, are prevalent in the age-related cataract population. Cataract surgery does not appear to be a significant risk factor for the development of new binocular vision anomalies. A pre-existing binocular vision anomaly is the main risk factor for predicting a post-operative binocular vision anomaly in this population.

Impact of Degraded Optics on Monocular and Binocular Vision: Lessons from Recent Advances in Highly-Aberrated Eyes

PURPOSE

Optical imperfections of the eye, characterized by higher-order wavefront aberrations, are exaggerated in corneal disease (e.g., keratoconus) and iatrogeny (e.g., keratorefractive surgery for myopia correction, keratoplasty for optical clarity restoration). This article reviews the recent advances on this topic for a comprehensive understanding of how optical degradations in disease models impact retinal image quality and monocular and binocular visual performance.

METHODS

Published literature over the last decade on retinal image quality and/or monocular and binocular visual functions with corneal irregularity was reviewed based on their relevance to the current topic, study population and strength of study design. The literature was summarized into four themes: 1) wavefront errors and retinal image quality of highly aberrated eyes, 2) monocular and binocular vision loss consequent to degraded optics and visual strategies to optimize performance, 3) impact of optical correction modalities on visual performance and 4) implications for clinical management of patients.

RESULTS

Across the 46 articles reviewed, the results clearly indicated that an increase in higher-order aberrations across these conditions had a significant negative impact on the patient's retinal image quality, and monocular and binocular visual functions. Interocular differences in retinal image quality deteriorated visual performance more than an overall worsening of image quality bilaterally. Minimizing optical degradation using rigid contact lenses and adaptive optics technology significantly improves retinal image quality and monocular and binocular vision, but performance remains sub-optimal relative to age-similar healthy controls.

CONCLUSION

Corneal disease and iatrogeny are useful models to understand the impact of optical degradation on retinal image quality and visual performance. Clinical management will greatly benefit from equalizing retinal image quality of both eyes of these patients. Future studies that deepen our understanding of the structure-function relation in these conditions are desirable for advancing vision science in this area and for developing novel clinical management strategies.

Changes in Accommodative and Binocular Function following Phakic Intraocular Lens for High and Low-to-Moderate Myopia

The aim was to evaluate accommodative and binocular function of phakic intraocular lens implantable collamer lens (ICL) in high and low-to-moderate myopia. Prospective comparative cohort study with 38 myopic patients who underwent ICL implantation were divided into two groups of 19 patients, each one based on the spherical equivalent (SE): high-power (SE ≤ −6 D) and low-to-moderate (SE > −6 D). The push-up amplitude of accommodation (AA), monocular accommodative facility (MAF), distance and near ocular deviation, near convergence amplitude, near point convergence (NPC), stereopsis, and accommodative convergence/accommodation (AC/A) ratio were assessed before surgery and 1 week and 1 month postoperatively. The mean residual refractive error at 1 month after surgery improved in both groups, 0.18 ± 0.34 D and 0.09 ± 0.26 D, respectively (p < 0.001). There was a significant decrease in AA in both groups between preoperatively and at 1-week (p = 0.001; p = 0.008, respectively) and 1-month follow-up (p = 0.001; p = 0.008). For the rest of the binocular measurements, no statistically significant postoperative changes were found in any group. This finding suggests follow-up studies on amplitude of accommodation in phakic intraocular lens ICL implantation.

Stereopsis after corneal refractive surgeries: a systematic review and meta-analysis

PURPOSE

To systematically review the published manuscripts on stereopsis after corneal refractive surgery.

METHODS

The Web of Science, PubMed, Scopus, ProQuest, Clinical Key, Embase, and Cochrane Library were searched for relevant articles published until August 2020. The fixed- or random-effects models were used to estimate the Weighted mean difference (WMD) or Relative risk (RR) and 95% Confidence interval (CI) for postoperative stereopsis changes and incidence when applicable. Meta-regression was conducted for adjusting the effects of potential confounders.

RESULTS

Seven studies (1266 eyes) in adults and ten studies in pediatrics (259 eyes) were included. In adults, stereopsis improved significantly compared to the preoperative state (WMD = - 27.4, 95% CI = - 40.0, - 14.7; I² = 97.8%; P < 0.001). In pediatrics, proportion of patients with stereoacuity postoperatively was 2.18 times compared to preoperative evaluation. (RR = 2.18, 95% CI = 1.2, 3.9; I² = 68.6%, P < 0.001).

CONCLUSIONS

Stereopsis improves after corneal refractive surgery in adults and pediatrics.

Binocular visual function after unilateral versus bilateral implantation of segmented refractive multifocal intraocular lenses: a pilot study

PURPOSE

To evaluate binocular visual function after unilateral and bilateral implantation of segmented refractive multifocal intraocular lenses (MIOLs).

METHODS

This prospective comparative pilot study included patients who underwent SBL-3 (Lenstec; + 3.00 D) implantation at Peking University Third Hospital. Patients were divided into two groups (monocular or binocular surgery). Thirty-two patients with emmetropic presbyopic contralateral eyes and 49 patients with bilateral SBL-3 implantation within a week between eyes were included in the unilateral SBL-3 and bilateral groups, respectively. At 3-month follow-up, the main outcomes were binocular uncorrected distant, intermediate, and near visual acuity (UDVA, UIVA, and UNVA). Secondary outcomes included binocular best-corrected visual acuity at all distances, defocus curve, contrast sensitivity, photic phenomena, spectacle independence, patient satisfaction, and National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) score. The essential perceptual phenomena constituting binocular vision, simultaneous perception, fusion, and stereopsis were also evaluated.

RESULTS

Both groups showed similar binocular UDVA and UIVA, but UNVA was significantly better in the bilateral group (0.07 ± 0.07 versus 0.12 ± 0.07, P = 0.008). Better binocular defocus curve at intermediate to near focal points, higher percentage of spectacle independence at near distance, and NEI-VFQ-25 near activity scores were observed in the bilateral group. No significant differences in contrast sensitivity, photic phenomena, overall satisfaction, other NEI-VFQ-25 subscales, fusional amplitude, and stereoacuity were found between groups.

CONCLUSION

Unilateral implantation of segmented refractive MIOL provided desirable distant visual acuity and high patient satisfaction, but inferior intermediate and near visual outcomes compared with bilateral implantation.

Nearwork-induced transient myopia and accommodation function before and after laser-assisted in situ keratomileusis surgery

Purpose

To assess the change in Near Induced Transient Myopia (NITM) and other accommodation parameters, before and after undergoing LASIK surgery for myopia correction.

Methods

Twenty-nine myopic subjects were recruited from a tertiary eye hospital in India. Age range was 21 to 35 years with an average age of 26.1 ± 3.5 years. Mean spherical equivalent was -3.86 D ± 1.50 D presurgery. NITM, lag of accommodation, near point of convergence (NPC), accommodative amplitude (AA), and binocular near accommodative facility (AF) were measured. All data were collected 21 days prior to and 30 days after LASIK surgery.

Results

NITM, lag of accommodation and amplitude of accommodation were significantly lower (NITM -0.05 ± 0.15, Lag 0.38 ± 0.38, AA 10.27 ± 2.24) after surgery when compared to before (NITM 0.26 ± 0.12, Lag 0.77 ± 0.51, AA 12.18 ± 2.02; P < 0.001). Accommodative facility increased and near point of convergence was significantly more distal following surgery (AF 10.70 ± 2.29, NPC 7.96 ± 1.63) when compared to prior (AF 8.65 ± 2.74, NPC 5.62 ± 1.71; P < 0.001).

Conclusion

Significant changes in NITM and accommodation function should be expected in the short term following LASIK surgery. This study supports the importance of evaluating accommodative parameters and patient counselling prior to and following refractive surgery.

Diplopia and Strabismus After Corneal Refractive Surgery

INTRODUCTION

Diplopia and strabismus are known complications after corneal refractive surgery (CRS). Within the U.S. Armed Forces, refractive surgery is used to improve the operational readiness of the service member, and these complications could cause significant degradation to their capability. This study was performed in order to identify the incidence of strabismus and diplopia following CRS within the U.S. Military Health System.

METHODS

A retrospective review of all patients who underwent photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) in the Department of Defense from January 2006 through September 2013 was designed and approved by the Naval Medical Center Portsmouth Institutional Review Board. The military health system data mart was queried for all patients who underwent one of these procedures and subsequently had an International Classification of Disease-9 code for any strabismus or diplopia through 2014 allowing at least 1 year of follow-up. We then calculated the incidence of both diplopia and strabismus for these procedures as the primary measure and the overall prevalence as a secondary measure.

RESULTS

A total of 108,157 patients underwent PRK or LASIK during our study period with 41 of these patients subsequently having a diagnosis of diplopia or strabismus. After chart review, 16 of these patients were excluded resulting in 25 patients for inclusion in either the strabismus (23 patients, 0.02%) or diplopia (3 patients, 0.003%) cohorts with one patient having both. Of the 23 patients with postoperative strabismus, 4 were new cases giving an incidence of 0.004% and 2 new cases of diplopia for an incidence of 0.002%.

CONCLUSION

Diplopia and strabismus are rare complications after CRS in the U.S. military population. These procedures continue to increase the operational readiness of our service members with minimal risk of these potentially debilitating complications. Overall, this study provides support for the continued use of PRK and LASIK despite study limitations related to the use of large databases for retrospective review. Future prospective studies using delineated preoperative and postoperative examinations with sensorimotor testing included may be able to resolve the limitations of this study.

Effect of corneal refractive surgery on accommodative and binocular dysfunctions among civilian pilots in Southwest China

Background

To analyze whether corneal refractive surgery (CRS) is associated with the distribution of different accommodative dysfunctions (ADs) and binocular dysfunctions (BDs) in civilian pilots. A further aim was to analyze the percentages and visual symptoms associated with ADs and/or BDs in this population.

Methods

One hundred and eight civilian pilots who underwent CRS from January 2001 to July 2012 (age: 30.33 ± 4.60 years) were enrolled, the mean preoperative SE was − 1.51 ± 1.15 D (range: − 1.00- − 5.00 D). Ninety-nine emmetropic civilian pilots (age: 29.64 ± 3.77 years) who were age- and sex-matched to the CRS group were also enrolled. Refractive status, accommodative and binocular tests of each subject were performed. Visually related symptoms were quantified using the 19-item College of Optometrists in Vision Development Quality of Life (COVD-QOL) questionnaire. The 19 items were summed to obtain visual symptom scores that might indicate visual dysfunctions. The chi-square test was used to analyze differences in percentages of ADs and/or BDs between the CRS and emmetropic groups. The Mann-Whitney U test was used to compare visual symptom scores between pilots with ADs and/or BDs and pilots with normal binocular vision.

Results

No significant difference was observed between the CRS and emmetropic groups in the overall prevalence of ADs and BDs (15.7% and 15.2% in the CRS and emmetropic groups, respectively; P = 0.185). ADs were present in 4.63% and 3.03% of the CRS and emmetropic group, respectively. BDs were observed in 11.1% and 12.1% of the CRS and emmetropic group, respectively, yielding no significant differences between the groups in the prevalence of ADs or BDs (AD: P = 0.094; BD: P = 0.105). Pilots with ADs and/or BDs had significantly more visual symptoms than pilots with normal binocular vision (p < 0.001).

Conclusions

CRS for civilian pilots with low-moderate myopia might not impact binocular functions. ADs and/or BDs commonly occur in both emmetropia pilots and pilots who undergo CRS, and pilots with ADs and/or BDs are associated with increased symptoms. This study confirms the importance of a full assessment of binocular visual functions in detecting and remedying these dysfunctions in this specific population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01855-0.

The Modulation of Laser Refractive Surgery on Sensory Eye Dominance of Anisometropia

Purpose

To evaluate the effect of laser refractive surgery on sensory eye dominance of anisometropia.

Methods

A total of 156 subjects with nonanisometropic myopia and 70 subjects with anisometropic myopia were enrolled in the first part of the study. The dichoptic motion coherence threshold technique was applied to collect the normal dataset and distribution of sensory eye dominance. The second part of the study included 40 subjects with nonanisometropic myopia and 40 subjects with anisometropic myopia who received the femtosecond laser-assisted in situ keratomileusis (Fs-LASIK). A comprehensive ophthalmologic evaluation was performed with particular attention to sensory eye dominance preoperatively and one-week and one-month postoperatively. The ocular dominance index (ODI) was applied to evaluate the subject's overall degree of sensory ocular dominance. Visual acuity, sighting eye dominance, and stereo acuity were also accessed.

Results

In experiment one, the mean ODI in the nonanisometropic group and the anisometropic group was 1.48 ± 0.63 and 1.95 ± 1.07, respectively. The ODI values of the anisometropic group were significantly higher than those of the nonanisometropic group (Mann–Whitney U test, P < 0.001). The demographics information and the distribution of ODI values in both groups are summarized in tables and figures. In experiment two, all LASIK procedures were uneventful and no postoperative complications were observed during the postoperative follow-up. Preoperatively, the ODI values of the anisometropic LASIK group were significantly higher than those of the nonanisometropic LASIK group, which was consistent with the results of part 1. However, one week after operation, the mean ODI values of the anisometropic LASIK group had significantly decreased from 1.89 ± 1.09 to 1.39 ± 0.44. And, the mean ODI values slightly increased to 1.65 ± 0.61 one-month postoperatively. In the nonanisometropic LASIK group, there were no statistically significant differences of ODI changes among preoperative, post-one-week and post-one-month visits. The demographics information and the changes of ODI of both LASIK groups are summarized in tables and figures.

Conclusion

Stronger sensory eye dominance is seen in the subjects with anisometropic myopia compared to subjects with nonanisometropic myopia. The strong sensory dominance of anisometropia becomes more balanced at one week of postoperation but returns to the preoperative level after one month. Laser refractive surgery had a short-term modulation of sensory eye dominance.