Ocular dominance in cataract surgery: research status and progress.

Ocular dominance (OD), a commonly used concept in clinical practice, plays an important role in optometry and refractive surgery. With the development of refractive cataract surgery, the refractive function of the intraocular lens determines the achievement of the postoperative full range of vision based on the retinal defocus blur suppression and binocular monovision principle. Therefore, OD plays an important role in cataract surgery. OD is related to the visual formation of the cerebral cortex, and its plasticity suggests that visual experience can influence the visual system. Cataract surgery changes the visual experience and transforms the dominant eye, which confirms the plasticity of the visual system. Based on the concept and mechanism of OD, this review summarizes the application of OD in cataract surgery.

Unilateral intraindividual comparison and bilateral performance of a monofocal spherical and diffractive extended depth of field intraocular lens mix-and-match approach.

BACKGROUND: To evaluate the intraindividual visual performance of a spherical and extended depth of field (EDOF) IOL used in a mix-and-match approach. METHODS: Single centre (tertiary care centre), retrospective consecutive case series. Included patients had uneventful cataract surgery with implantation of a spherical monofocal IOL (CT Spheris 204) in the dominant eye and a diffractive EDOF IOL (AT LARA 829) in the non-dominant eye. Monocular and binocular defocus curves and visual acuity at various distances were assessed. In addition, binocular reading speed, contrast sensitivity, and patient satisfaction using QOV, Catquest 9SF, and glare/halo questionnaires are reported. RESULTS: A total of 29 patients (58 eyes) were included. We observed significant intra-individual differences for monocular DCIVA, DCNVA, UIVA, and UNVA. There were no differences in monocular BCDVA or UDVA. The monocular defocus curves for the two IOLs significantly differed at defocus steps between -1.0 and -3.5 D. 93.10% of patients reported they would opt for the same combination of IOLs. CONCLUSION: Excellent uncorrected and corrected distance visual acuity was demonstrated in both groups. The mix-and-match approach described in this study yielded good intermediate vision and improved near vision with high-patient satisfaction.

Comparison of visual performances of enhanced monofocal versus standard monofocal IOLs in a mini-monovision approach.

PURPOSE: To compare visual performance and quality of life in patients who received either monofocal intraocular lenses (IOLs) or an enhanced monofocal IOL in a mini-monovision target approach. BACKGROUND: Monofocal lenses are the most common intraocular IOLs employed during cataract surgery because of their relatively low cost and good performance for distance sight. However, these lenses, generally, do not exonerate patients from spectacle use for near or intermediate tasks. On the other hand, enhanced monofocal IOLs (e.g., Tecnis Eyhance®) feature optical properties providing patients with good intermediate visual outcomes. Satisfactory near visual acuity results, regardless of IOL type, may be achieved through mini-monovision. We assessed visual performance outcomes between these IOLs, in a mini-monovision approach. METHODS: Retrospective case series of patients who underwent bilateral cataract surgery at our institution with implantation of Alcon SN60WF, J&J Tecnis DCB00 or J&J Tecnis Eyhance® DIB00 with a pre-operative mini-monovision target. The postoperative spherical equivalent was measured by a Nidek® auto-refractometer. Best-uncorrected binocular visual acuity (BUBVA) at far (3 m), intermediate (66 cm), and near (40 cm) distance and binocular contrast sensitivity (100%, 25%, and 5%, all at 1 m) were measured using Snellen and Pelli-Robson charts, respectively. Visual performance in daily life was evaluated with the Cataract VF-14 quality of life survey. RESULTS: 71 patients (35 in the monofocal IOL and 37 enhanced IOL group) were enrolled. Patients implanted with enhanced IOL exhibited statistically significant better BUBVA results at 66 cm and 40 cm distances compared to patients in the monofocal group. Additionally, patients in the enhanced IOL group presented a better contrast sensitivity in lower contrast conditions (5%) than patients with monofocal IOL. The quality of life survey showed statistically significant higher scores in daily activities without spectacles for patients with enhanced IOL. CONCLUSION: Enhanced monofocal IOLs, combined with a mini-monovision approach, provided patients with good visual performance at all tested distances, with superiority of enhanced monofocal IOLs at near and intermediate distances.

Comparison of bilateral implantation of an extended depth of focus lenses and a blend approach of extended depth of focus lenses and bifocal lenses in cataract patients.

BACKGROUND: To compare the visual outcomes, spectacle independent rate and stereopsis in patients who underwent bilateral implantation of extended depth of focus (EDOF) intraocular lens (IOL), or a blend approach of EDOF and bifocal IOL. METHODS: A total of 60 cataract patients, who were scheduled for phacoemulsification and intraocular lens implantation in both eyes in West China Hospital of Sichuan University, were enrolled and divided into Micro monovision group(-0.5D~-1.0D), Non-micro monovision group (< 0.5D) with Symfony IOL, and Mixed group with Symfony and ZMB00 IOLs. Three months postoperatively, we compared the visual acuity, modulation transfer function (MTF), defocus curve, stereopsis, spectacle independence, and photic phenomena among the three groups. RESULTS: Compared to the Non-micro monovision group (UNVA: 0.07 ± 0.04), Micro monovision group (UNVA: 0.00 ± 0.07, P < 0.001) and Mixed group (UNVA: -0.02 ± 0.06, P < 0.001) showed improvement in binocular uncorrected near visual acuity (UNVA). Additionally, Mixed group exhibited lower MTF10 (MTF10: 0.38 ± 0.24) and point spread function (PSF: 0.192 ± 0.269) results in their non-dominant eye compared to both Micro monovision group (MTF10: 0.56 ± 0.21, P = 0.027; PSF: 0.417 ± 0.282, P = 0.034) and Non-micro monovision group (MTF10: 0.55 ± 0.19, P = 0.038; PSF: 0.408 ± 0.285, P = 0.003). Spectacle independence for near vision were higher in both the Micro monovision (45%) and Mixed (55%) group compared to the Non-micro monovision group (40%). The Mixed group also reported higher incidence of photic phenomena (25%). However, there were no significant differences in stereoscopic function among the three groups. CONCLUSION: Both micro monovision and mix-and-match methods can help patients to obtain better visual outcomes at different distances. Mix-and-match method has better near visual acuity, while micro monovision method has better intermediate visual acuity. Non-micro monovision methods will affect patients' near vision outcomes. Binocularly implanted EDOF IOL has better contrast sensitivity. CLINICAL TRIAL REGISTRATION: Registration date:11/07/2023. TRIAL REGISTRATION NUMBER: ChiCTR2300073433. TRIAL REGISTRY: West China Hospital of Sichuan University retrospectively registered.

Case report of the evidence of a spontaneous Reverse Pulfrich effect in monovision after cataract surgery.

BACKGROUND: Cataracts affect the optics of the eye in terms of absorption, blur, and scattering. When cataracts are unilateral, they cause differences between the eyes that can produce visual discomfort and harm binocular vision. These interocular differences can also induce differences in the processing speed of the eyes that may cause a spontaneous Pulfrich effect, a visual illusion provoking important depth misperceptions. Interocular differences in light level, like those present in unilateral cataracts, can cause the Classic Pulfrich effect, and interocular differences in blur, like those present in monovision, a common correction for presbyopia, can cause the Reverse Pulfrich effect. The visual system may be able to adapt, or not, to the new optical condition, depending on the degree of the cataract and the magnitude of the monovision correction. CASE PRESENTATION: Here, we report a unique case of a 45-year-old patient that underwent unilateral cataract surgery resulting in a monovision correction of 2.5 diopters (D): left eye emmetropic after the surgery compensated with a monofocal intraocular lens and right eye myopic with a spherical equivalent of -2.50 D. This patient suffered severe symptoms in binocular vision, which can be explained by a spontaneous Pulfrich effect (a delay measured of 4.82 ms, that could be eliminated with a 0.19 optical density filter). After removing the monovision with clear lens extraction in the second eye, symptoms disappeared. We demonstrate that, at least in this patient, both Classic and Reverse Pulfrich effects coexist after unilateral cataract surgery and that can be readapted by reverting the interocular differences. Besides, we report that the adaptation/readaptation process to the Reverse Pulfrich effect happens in a timeframe of weeks, as opposed to the Classic Pulfrich effect, known to have timeframes of days. Additionally, we used the illusion measured in the laboratory to quantify the relevance of the spontaneous Pulfrich effect in different visual scenarios and tasks, using geometrical models and optic flow algorithms. CONCLUSIONS: Measuring the different versions of the Pulfrich effect might help to understand the visual discomfort reported by many patients after cataract surgery or with monovision and could guide compensation or intervention strategies.

Bilateral simultaneous cataract surgery and intraocular lens implantation in an adult female chimpanzee (Pan troglodytes) inducing monovision.

BACKGROUND: Cataract is the major cause of visual impairment in humans. Phacoemulsification with intraocular lens (IOL) implantation is the standard technique for cataract treatment with a high success rate. In a few cases, the surgical cataract procedure and lens implantation have been applied in non-human primates. CASE DESCRIPTION: A +/- 40-year-old female chimpanzee (Pan troglodytes) in captivity was diagnosed with mature cataract optical density (OD) and posterior subcapsular cataract combined with cortical opacities OS after ophthalmic examination. To restore vision and facilitate far- and near sight, phacoemulsification OU with +22.5 diopter (D) IOL implantation OD and + 24 D OS were performed. Despite complicated surgery OD due to posterior capsular rupture, the outcome was successful during 1-year follow-up. The chimpanzee regained adequate vision, normal behavior, and was successfully re-introduced to her group of chimpanzees. CONCLUSION: This is the first case report of a simultaneous bilateral cataract surgery with IOL implantations in both eyes, targeting emmetropia OS and near vision OD resulting in monovision, in a chimpanzee. Vision was restored without postoperative complications.

Long-term follow-up for monovision surgery by Implantable Collamer Lens V4c implantation for myopia correction in early presbyopia.

PURPOSE: To investigate the long-term safety and efficacy of monovision surgery using implantable collamer lens V4c (ICL V4c) implantation in myopic patients with early presbyopia. SETTING: Eye and ENT Hospital of Fudan University, Shanghai, China. DESIGN: Prospective case series study. METHODS: This study included 64 eyes of 32 patients with early presbyopia, who underwent bilateral ICL V4c implantation for myopia correction. Parameters, including mean spherical equivalent (SE), uncorrected distance visual acuity, corrected distance visual acuity, intraocular pressure, endothelial cell density, presbyopic add power, visual acuity (logMAR) of dominant eyes (D-eye), nondominant (nD-eye) eyes, and both eyes (Bi) at 0.4 m, 0.8 m, and 5 m were recorded at the last follow-up. RESULTS: All surgeries were uneventful. At the last follow-up, the safety indices were 1.23 ± 0.18 (D-eyes) and 1.21 ± 0.18 (nD-eyes) (p > 0.05); the efficacy indices were 0.95 ± 0.27 (D-eyes) and 0.92 ± 0.28 (nD-eyes) (p < 0.05), the SE was -0.62 ± 0.47 D (D-eyes); and - 1.21 ± 0.78D (nD-eyes) (p < 0.05), presbyopic add power was 1.31 ± 0.58 D. The visual acuity (logMAR) of D-eyes, nD-eyes, and binocular (Bi) at 5.0 m were: 0.06 ± 0.15 (D-eye), 0.21 ± 0.18 (nD-eye), (p < 0.01), and 0.04 ± 0.13 (Bi); 0.8 m: 0.03 ± 0.18 (D-eye), 0.08 ± 0.16 (nD-eye), (p > 0.05), and - 0.02 ± 0.11 (Bi); 0.4 m: 0.08 ± 0.09 (D-eye), - 0.02 ± 0.08 (nD-eye), (p < 0.001), and - 0.03 ± 0.09 (Bi). Subjects were very satisfied or felt excellent with their visual acuity at near (81.25%) and far distances (87.50%), respectively (versus preoperative, p < 0.001). CONCLUSION: Monovision surgery using ICL V4c implantation is safe and practicable for correction of myopes with presbyopia, with long-term efficacy at near and far distances and patient satisfaction.

Partial monovision achieved by unilateral implantation of a multifocal add-on lens with bilateral pseudophakia: evaluation and results.

PURPOSE: To assess the results of partial monovision (PMV) in comparison to a bilateral monofocal implantation (MMV). METHODS: The PMV group was treated bilaterally with a monofocal intraocular lens (IOL) implantation, followed 3 months later by the implantation of a multifocal AddOn® lens (+ 3.00 D) into the non-dominant eye. The MMV group received a bilateral monofocal IOL implantation intending to achieve a slight anisometropia (0.0 D/ - 0.50 D). The near visual acuity (UNVA), intermediate visual acuity (UIVA), distance visual acuity (UDVA), defocus curve, and Lang-Stereotest II were conducted uncorrected, binocular, and minimum 3 months after the last operation. For the contrast sensitivity test, the patients were refractively corrected. The Quality of Vision Questionnaire (QoV), Visual Function Questionnaire (VF-14), spectacle independence, and general satisfaction were also assessed. RESULTS: A total of 27 PMV patients and 28 MMV patients without ocular diseases relevant to visual acuity were examined. The PMV group was significantly better at UNVA (0.11 ± 0.08 logMAR vs 0.56 ± 0.16 logMAR) and between - 2.00 and - 4.00 D in the defocus curve (p < 0.001). At the UIVA, the PMV group was slightly better (0.11 ± 0.10 logMAR vs 0.20 ± 0.18 logMAR) but not significant (p = 0.054). The UDVA (- 0.13 ± 0.09 logMAR vs - 0.09 ± 0.14 logMAR) (p = 0.315) and contrast sensitivity (p = 0.667) revealed no differences between the groups. The stereo vision was in favor of PMV (p = 0.008). Spectacle independence was statistically better for PMV at distance, intermediate, and near (distance p = 0.012; intermediate p < 0.001; near p < 0.001). In the VF-14 Questionnaire, the PMV was statistically superior (p < 0.001). The QoV Questionnaire showed no differences regarding frequency and severity of visual disturbances. Both groups were highly satisfied (p = 0.509). CONCLUSION: Patients with PMV are more independent of glasses and are able to read without disadvantages in distance vision, due to halos and glare. The concept of PMV is well suited for the desire of eyeglass independence, without optical side effects.

[Outcomes of bilateral implantation of trifocal and extended depth of focus IOLs]. / Rezul'taty bilateral'noi implantatsii trifokal'noi intraokulyarnoi linzy i intraokulyarnoi linzy s rasshirennoi glubinoi fokusa.

In recent years, a new class of extended depth of focus (EDOF) intraocular lenses (IOLs) has become available on the market. There is only a limited number of scientific papers comparing trifocal and EDOF IOL data, and the results are often contradictory. PURPOSE: Comparative analysis of the results of trifocal and EDOF IOL implantation in patients with presbyopia and/or cataract. MATERIAL AND METHODS: This prospective study included 72 patients (144 eyes) after bilateral implantation of either Tecnis Symfony EDOF IOL (18 patients, 36 eyes; group I) or AcrySof PanOptix trifocal IOL (54 patients, 108 eyes; group II). In 18 patients out of 72 (25%) the implantation involved mini-monovision, i.e. the calculation of the IOL power on the nondominant eye was performed at -0.5 D. The average follow-up period for the patients was 7.1±1.2 months. RESULTS: There was a significant (p<0.05) increase in uncorrected near visual acuity (UCNVA), uncorrected intermediate visual acuity (UCIVA) and uncorrected distance visual acuity (UCDVA) at the maximum follow-up time compared to the preoperative indices in all groups. Group II was characterized by slightly better UCNVA dynamics (0.85±0.13 versus 0.2±0.04 before surgery, as comparted to 0.78±0.11 versus 0.19±0.06 before surgery in group I), but differences were not statistically significant (p>0.05). Statistically significant differences (p=0.046) were observed when comparing best corrected near vision acuity (BCNVA) in groups I and II (0.79±0.05 and 0.98±0.08, respectively) at 6 months compared to the preoperative period (0.62±0.09 and 0.6±0.11, respectively). CONCLUSION: Trifocal IOL implantation was associated with acceptable near and far vision correction and a higher frequency of adverse optical phenomena, while implantation of the EDOF IOL was associated with slightly better correction of intermediate vision and a significantly lower incidence of halo and glare. Patients were satisfied with the outcomes of surgery in all cases.

Comparison of reading performance with low add bifocal and extended depth of focus intraocular lenses implanted with mini-monovision.

PURPOSE: To evaluate reading performance, preferred reading distance, and spectacle independence in patients implanted with a low add multifocal or an extended depth of focus (EDOF) intraocular lens (IOL) after phacoemulsification. METHODS: In this prospective study, patients were randomized into two groups: the diffractive multifocal Tecnis + 2.75 D (ZKB00) IOL (Tecnis + 2.75 group; 15 patients) or the EDOF Tecnis Symfony (ZXR00) IOL (Symfony group; 14 patients) for bilateral implantation with mini-monovision. Reading performance parameters (reading acuity [RA], critical print size [CPS], and maximum reading speed [MRS]) were evaluated with MNREAD acuity charts at 40 cm, and preferred reading distances and spectacle independence for near activities were assessed preoperatively and at the postoperative 1st, 3rd, and 6th months. RESULTS: At the postoperative 6th month, binocular logMAR UNVA and DCNVA were significantly better in the Symfony group than in the Tecnis + 2.75 group (UNVA: 0.15 ± 0.07 vs. 0.22 ± 0.08, p = 0.046; DCNVA: 0.21 ± 0.05 vs. 0.28 ± 0.07, p = 0.043; respectively). There was no significant difference in reading performance parameters between the groups; however, the Symfony group preferred significantly closer reading distance than the Tecnis + 2.75 group (42.00 ± 4.67 cm; 45.87 ± 5.32 cm, respectively, p = 0.030). At the postoperative 6th month, 14.3% and 26.7% of patients reported that they needed spectacles, rarely or occasionally, for near activities in the Symfony and Tecnis + 2.75 groups, respectively (p > 0.05). CONCLUSIONS: When implanted with mini-monovision, although functional near visual acuity and a high degree of spectacle independence at near distances were achieved with both IOLs, patients implanted with the EDOF IOL preferred closer reading distance than those implanted with the low add diffractive multifocal IOL.

Visual outcomes in hyperopic myopic and emmetropic patients with customized aspheric ablation (Q factor) and micro-monovision.

PURPOSE: To evaluate the visual outcomes, visual performance, and stereoacuity in presbyopic patients following treatment by a change in the corneal asphericity and micro-monovision. METHODS: Presbyopic patients with diverse refractive errors and emmetropes (n = 30 eyes) were treated with a custom Q-ablation profile and micro-monovision in the non-dominant eye. There with a difference of Q - 0.30 in the Q profiles between dominant and non-dominant eyes. Patients were assigned in two groups based on the preoperative spherical equivalent (Group 1 + 4.00 to + 0.50, and group 2 neutral to - 3.00). Binocular uncorrected distance visual acuity (binocular UCVA), best-corrected visual acuity (BCVA), binocular uncorrected near visual acuity (binocular UNVA) preoperative and postoperative, spherical equivalent refraction, contrast sensitivity, and stereopsis were analyzed at 1, 3, and 6 months. RESULTS: The mean age was 52.6 ± 5.1 (SD) years. At six months post-operation, the mean binocular uncorrected distance visual acuity (binocular UDVA) was 0.15 ± 0.04 logMAR (20/25-) in group 1, and 0.11 ± 0.05 logMAR (20/25) in group 2, and binocular uncorrected near vision UNVA was 0.5 ± 0.1 M (20/25 J2) in group 1 and 0.45 ± 0.2 M (20/25 J2) group 2. An increase in stereoacuity was found in both groups. CONCLUSIONS: The correction of refractive defects using customized corneal asphericity was an effective treatment in presbyopic patients. Furthermore, the treatment was well tolerated in this group of patients. Following surgery, the quality of vision was adequate, and the stereovision improved in this cohort of patients.

Crossed versus conventional pseudophakic monovision for high myopic eyes: a prospective, randomized pilot study.

BACKGROUND: Aiming at spectacle independence, conventional pseudophakic monovision has been widely used in myopia patients with bilateral monofocal intraocular lens implantation. However, the crossed monovision, which is to correct the dominant eye for near vision and the non-dominant eye for distant vision, has been mentioned preferable for high myopic cataract patients by some studies. We have conducted this study to compare clinical results to assess the feasibility of conventional and crossed monovision for high myopic pseudophakic patients by comparing patient satisfaction, visual function and spectacle independence. METHOD: Forty-sixth high myopia patients were divided into two groups: 22 in crossed monovision group with patients whose refraction targeted to - 2.00 diopters (D) in the dominant eye and - 0.50D in the non-dominant eye; 24 in conventional monovision group with patients whose refraction targeted to - 0.50D in the dominant eye and - 2.00D in the non-dominant eye. Binocular uncorrected distance visual acuity (BUDVA), binocular uncorrected near visual acuity (BUNVA), binocular corrected distant visual acuity (BCDVA), binocular corrected near visual acuity (BCNVA), contrast visual acuity and stereoacuity were examined at postoperative 2 weeks, 1 month and 3 months. Questionnaires were completed by patients 3 months after binocular surgery to evaluate patients' satisfaction and spectacle independence. RESULTS: The conventional monovision and the crossed monovision group showed no significant differences of mean BUDVA, BUNVA, BCDVA, BCNVA 2 weeks, 1 month or 3 months postoperatively (P > 0.05). There was no difference in the bilateral contrast sensitivity or stereoscopic function between the convention conventional and crossed monovision groups (P > 0.05). Patient satisfaction with near and distant vision, as well as spectacle dependence did not differ significantly between the two groups (P > 0.05). CONCLUSION: Crossed pseudophakic monovision exhibited similar visual function when compared with conventional monovision technique, which indicates that it is an effective option to improve the visual functionality and quality of life for high myopic patients who considering bilateral cataract surgery. TRIAL REGISTRATION: The Institutional Review Board and Ethics committee of the First Affiliated Hospital of Chongqing Medical University, Chongqing, China. The trial registration was submitted in September 2018 and passed on March 18, 2020, and the registration number is: ChiCTR2000030935 .

Impact of monovision on dynamic accommodation of early presbyopes.

PURPOSE: To examine the impact of monovision on dynamic changes in accommodation, pupil responses, spherical aberration and resultant image quality in early presbyopes. METHODS: Refractive state, pupil size and spherical aberration levels were monitored in nine early presbyopes who exhibited some accommodation (40-50 years, mean = 42 ± 2.37 years) using a Shack-Hartmann aberrometer as a binocularly viewed stimulus stepped closer (from 2 m to 40 cm), or farther (from 40 cm to 2 m). Comparison data from two fully presbyopic (i.e. non-accommodating) subjects (ages 46 and 61 years) and two young adults (ages 26 and 29 years) were also collected. Each subject was fit with four different refractive strategies: (1) both eyes corrected for 2 m, (2) both eyes corrected for 40 cm, (3) monovision with the measured right eye corrected for 2 m and, (4) monovision with the right eye corrected for 40 cm. Monochromatic image quality was quantified using the AreaMTF metric. RESULTS: When fit with monovision, the largest number of early presbyopes produce an accommodative response dominated by the right eye correction (distance or near) as the stimulus is abruptly changed from the retinal conjugate plane of one eye to that of the other eye. However, the accommodative responses in some early presbyopes were always dominated by the distance corrected eye, the near corrected eye, or by convergence. When the stimulus approached, the near corrected eye experienced high image quality only if there was no accommodative response. However, reduced image quality was observed if an accommodative response was initiated. Neither accommodation nor pupil response latencies were longer with monovision corrections compared with bilateral distance corrections (p > 0.05). In the early presbyopes, spherical aberration was reduced during near viewing, but primarily due to pupil miosis and not lens shape changes. CONCLUSION: As the stimulus was abruptly changed from the retinal conjugate plane of the distance corrected eye to that of the near corrected eye, most early presbyopes fit with monovision accommodated, which resulted in a decline, not an increase in image quality in the near corrected eye. These results reveal a non-optimal accommodative strategy in early presbyopes fit with monovision.

Monovision: Consequences for depth perception from large disparities.

Recent studies have confirmed that monovision treatment degrades stereopsis but it is not clear if these effects are limited to fine disparity processing, or how they are affected by viewing distance or age. Given the link between stereopsis and postural stability, it is important that we have full understanding of the impact of monovision on binocular function. In this study we assessed the short-term effects of optically induced monovision on a depth-discrimination task for young and older (presbyopic) adults. In separate sessions, the upper limits of stereopsis were assessed with participants' best optical correction and with monovision (-1D and +1D lenses in front of the dominant and non-dominant eyes respectively), at both near (62 cm) and far (300 cm) viewing distances. Monovision viewing resulted in significant reductions in the upper limit of stereopsis or more generally in discrimination performance at large disparities, in both age groups at a viewing distance of 300 cm. Dynamic photorefraction performed on a sample of four young observers revealed that they tended to accommodate to minimize blur in one eye at the expense of blur in the other. Older participants would have experienced roughly equivalent blur in the two eyes. Despite this difference, both groups displayed similar detrimental effects of monovision. In addition, we find that discrimination accuracy was worse with monovision at the 3 m viewing distance which involves fixation distances that are typical during walking. These data suggest that stability during locomotion may be compromised, a factor that is of concern for our older participants.

Immediate cortical adaptation in visual and non-visual areas functions induced by monovision.

KEY POINTS: Monovision is an optical correction for presbyopes that consists of correcting one eye for far distance and the other for near distance, creating a superimposition of an in-focus with a blurred image. Brain adaptation to monovision was studied in unexperienced observers by measuring visual evoked potentials from 64-channels. The first clear effect of monovision on visual evoked potentials was the C1 amplitude reduction, indicating that the unilateral blurring induced by monovision reduces feed-forward activity in primary visual area. Monovision led also to an increased amplitude of the P1 and pP1 components, with the latter originating in prefrontal regions. This effect probably works as an attentional compensatory activity used to compensate for the degraded V1 signal. ABSTRACT: A common and often successful option to correct presbyopia with contact lenses is monovision. This is an unbalanced correction across the two eyes where one eye is corrected for far vision and the other eye is corrected for near vision. Monovision is therefore a form of acquired anisometropia that causes a superimposition of an in-focus image with a blurred image. In spite of this visual anisometropia, monovision has been successfully used for many decadesl however the brain mechanism supporting monovision is not well understood. The present study aimed to measure the visual evoked potentials with a high-density electrode array (64-channel) in a group of presbyopes and to provide a detailed spatiotemporal analysis of the cortical activity after a short period of adaptation to monovision with contact lenses. When compared with a balanced eye near correction, monovision produced both a clear reduction of the earliest visual evoked potential components, the C1 and the N1, and an amplitude increase of the P1 and pP1. These results indicate that the unilateral blurring induced by wearing monovision contact lenses reduces feed-forward activity in the primary visual area and feedback activity in extrastriate areas (C1 and N1 reduction). Interestingly, other brain activities in both extrastriate visual areas (the P1 component) and in the anterior insula (the pP1 component) appear to compensate for this dysfunction, increasing their activity during monovision. These changes confirm the presence of fluid brain adaptation in visual and non-visual areas during monocular interferences.

Safety and satisfaction of myopic small-incision lenticule extraction combined with monovision.

BACKGROUND: To investigate the safety and optical quality of small-incision lenticule extraction (SMILE) combined with monovision, and patient satisfaction with the procedure. METHODS: The present study assessed a non-random case series involving 60 eyes of 30 patients (mean age 45.53 ± 3.20 years [range 41 to 52 years]) treated bilaterally using the VisuMax 500 system (Carl Zeiss Meditec, Jena, Germany) between January and July 2016. The target refraction was plano for the distance eye, and between - 0.5 and - 1.75 diopters (D) for the near eye. Visual acuity, refraction errors, ocular aberrations, and satisfaction questionnaire scores were calculated 1 year after surgery. RESULTS: All surgeries were uneventful, with a mean safety index of 1.03 and 1.04 in dominant and nondominant eyes, respectively. Binocular uncorrected distance visual acuity of all patients was ≥20/32, while binocular uncorrected near visual acuity was ≥20/40 1 year postoperatively. Higher-order aberration (0.45 ± 0.14, 0.51 ± 0.15 µm), spherical (0.18 ± 0.15, 0.21 ± 0.14 µm) and coma aberration (0.31 ± 0.16, 0.27 ± 0.17 µm) were identical between dominant and nondominant eyes after surgery. The overall satisfaction rate was 86.7% (26/30), with large contributions from age (OR = 1.76 95% CI: 1.03-2.53; P = 0.036). Binocular uncorrected distance visual acuity was related to preoperative spherical diopter (r = - 0.500; P = 0.005). CONCLUSIONS: Monovision appears to be a safe and effective option for myopia patients with presbyopia who are considering the SMILE procedure. Patients with younger age were more satisfied with the procedure.

Etiology and outcomes of secondary surgical intervention for dissatisfied patients after pseudophakic monovision.

PURPOSE: To evaluate the etiology and the clinical outcomes of secondary surgical interventions for dissatisfied patients after pseudophakic monovision. SETTING: Department of Ophthalmology, Kitasato University Hospital, Kanagawa, Japan. DESIGN: Retrospective case series. METHODS: This study comprised 12 eyes in 12 patients (age 66.2 ± 5.6 years) who underwent photorefractive keratectomy (PRK) enhancement to improve their dissatisfaction after pseudophakic monovision. We quantitatively assessed the visual and refractive outcomes and the subjective satisfaction measured using a visual analog scale, that ranged from 0 (very dissatisfied) to 10 (very satisfied), before and 3 months after PRK enhancement. RESULTS: Six (50%) of the 12 patients were dissatisfied with their various distance visions because of a large amount of anisometropia (≥2.50 D). Two (16.7%) were dissatisfied with their distance vision after conventional monovision because of residual cylindrical errors (≥0.75 D) in the dominant eye. Three (25%) was an unknown origin. The remaining one of the 12 patients was dissatisfied due to the unadaptability to crossed monovision. Eleven (91.7%) eyes were within ±0.5 D of the targeted correction after PRK enhancement. The overall satisfaction score was significantly improved, from 3.7 ± 2.4 (range 0-7) preoperatively to 6.0 ± 2.4 (range 2-9) postoperatively (p = 0.02). No vision-threatening complications were seen throughout the observation period. CONCLUSIONS: PRK enhancement was effective with predictable refractive results and thus improved patient satisfaction for dissatisfied patients after pseudophakic monovision. These findings also suggest that the accurate correction of refractive errors plays a key role in successful pseudophakic monovision.

Haigis and SRKT formulae accuracy for intentional myopic overcorrection.

PURPOSE: To investigate the influence of preoperative biometric parameters on the accuracy of Haigis and SRKT formulae in predicting postoperative target refraction. METHODS: Retrospective analysis of 108 eyes (70 patients) underwent uneventful phacoemulsification surgery with implant of Alcon-SN60WF intraocular lens (IOL). Forty-five eyes were intentionally targeted to myopia (-0.75 to -1.25 dpt), while the others targeted between 0 and -0.75 dpt. Preoperative axial length and keratometry (K) were measured with optical biometry (LENSTAR-Haag-Streit). Postoperative spherical equivalent was assessed 3 ± 2 months after surgery. RESULTS: There is a significant correlation between the mean keratometry (K) and the Haigis-SRKT prediction differences (P < 0.001; r = 0.749). Linear regression indicates that a decrease of 1 diopter (D) on K implies an increase of 0.23 D on the difference between formulae prediction. K alone does not influence the prediction error for both formulas. The difference between the two formulae is dependent on K (r = -0.75; P < 0.01). Moreover, eyes with K <43.75 targeted at myopia (n = 23) showed a significant myopic shift of -0.26 ± 0.09 dpt (P < 0.05) with Haigis, but a hyperopic shift of 0.24 ± 0.09 dpt (P < 0.05) with SRKT. CONCLUSION: Divergences between Haigis and SRKT formulae cause uncertainty in choosing the IOL. Our results indicate that, in eyes with lower preoperative K, an IOL targeted at myopia might result in a small, but significant myopic shift with the Haigis formula, while a hyperopic shift with the SRKT formula.

Optical Management Using Monovision and Yoked Prism for Acquired Strabismus and Nystagmus Secondary to a Neurodegenerative Disease.

Acquired involuntary eye movement disorders, including noncomitant strabismus, nystagmus, and saccadic dyskinesia, are common ocular manifestations of many neurodegenerative diseases. These patients may experience visual symptoms, such as blurred vision, diplopia, and oscillopsia, which can significantly impact their use of vision. The goal of the management for these patients is to reduce the visual symptoms using any combination of available management strategies. This case report discusses the effective optical management using the combination of spectacle monovision correction and yoked prism to improve visual symptoms in a patient with olivopontocerebellar atrophy.

Clinical Outcomes and Patient Satisfaction of an Enhanced Depth of Focus Intraocular Lens Targeted for Mini-Monovision.

Purpose: To assess the clinical outcomes, the rate of spectacle independence, and patient satisfaction of an enhanced depth of focus (EDOF) LuxSmart™ IOL targeted for mini-monovision in patients who had undergone bilateral cataract surgery. Methods: Twenty patients underwent bilateral LuxSmart IOL implantation with the non-dominant eye targeted for -0.50 diopters. Best-corrected distance (CDVA) and uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA) at 66 cm, uncorrected near visual acuity (UNVA) at 40 cm, and defocus curve were assessed. Patient-reported visual function was inquired by Catquest-9SF, and the rate of spectacle independence in all daily-life activities was calculated. The presence of photic phenomena was evaluated. A p-value lower than 0.05 was considered statistically significant. Results: The mean IOL power was +21.50 ± 4D (16.5-26D), and all were non-toric. Thirty-seven (92.5%) eyes were within ±0.5D of predicted target. The postoperative MRSE was 0.06 ± 0.42D and -0.45 ± 0.22D in dominant and non-dominant eyes. Every patient achieved distance binocular vision better than 0.1 logMAR. The non-dominant eyes showed lower CDVA (p<0.001). The UIVA was higher in non-dominant eyes (p<0.001). Binocular uncorrected near visual acuity was 0.12 ± 0.1, and uncorrected near visual acuity was higher in non-dominant eyes (p<0.001). LuxSmart IOL provided a sustained visual acuity of 0.3 logMAR or better between +1.00D and -2.50D. A total of 25% of patients reported frequent halos and glare. Despite achieving higher degrees of satisfaction, seven patients (35%) denied total spectacle independence in their daily-life activities, particularly for activities requiring continuous near vision. Conclusion: This study shows that LuxSmart EDOF IOL in mini-monovision strategy performs well for distance and intermediate vision. Although visual acuity for near also achieved very good results, the considerable rate of spectacle dependence, in particular for near, and the rate of photic phenomena do not support this IOL to be safely implanted in patients desiring spectacle independence at time of cataract surgery.