Binocular Visual Performance Research Articles

Visual Outcomes According to Age After Bilateral Implantation of Trifocal Intraocular Lenses.

To investigate the effect of age on visual outcomes after the bilateral implantation of trifocal intraocular lenses (IOLs). A total of 290 patients (580 eyes) who underwent bilateral implantation of a trifocal IOL were enrolled in this retrospective case-control study. Patients were divided into five age groups: 45 to 49, 50 to 54, 55 to 59, 60 to 64, and 65 years and older. Postoperative monocular uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively), uncorrected near visual acuity (UNVA), binocular distance-corrected defocus curve, spectacle dependence for near and distance vision, and patient satisfaction scores were compared among the five groups. The 45 to 49 years group had significantly better mean UDVA (0.02 ± 0.05 logMAR) and UNVA (0.02 ± 0.04 logMAR) than the 65 years and older group (0.06 ± 0.09 and 0.09 ± 0.09 logMAR; P = .029 and P < .001; respectively). However, no significant differences were observed in the mean CDVA among the groups. Binocular visual performance of the 45 to 49 years group was better than that of the 65 years and older age group at defocuses of +1.00, +0.50, -1.00, and -3.00 D. No significant differences were observed in spectacle dependence for near and distance vision or in patient satisfaction scores among the five groups. Bilateral implantation of trifocal IOLs can provide excellent near and distance vision in both young and older patients. However, UDVA and UNVA revealed considerably worse results in the older group, although no significant difference was observed in CDVA and postoperative refractive errors by age. [J Refract Surg. 2024;40(4):e270-e277.].

The value of assessing progressive loss of red/green and yellow/blue chromatic sensitivity in glaucoma

*Correspondence: franziska.rauscher@medizin.uni-leipzig.deThe value of assessing progressive loss of red/green and yellow/blue chromatic sensitivity in glaucoma.The study employed visual stimuli designed to isolate and reveal how spatial, temporal and chromatic aspects of visual processing change from normal sensitivity to extreme loss in glaucoma. The experiments carried out examined the fovea and each of four paracentral retinal regions, arranged diagonally away from fixation at an eccentricity of 6°. Spatial vision was investigated by measuring both absolute detection thresholds and functional contrast sensitivity using Landolt ring stimuli (Ophthalmic Physiol Opt 2022;42:1363–1378). These psychophysical tests based on Landolt C optotypes measure both detection thresholds and gap orientation discrimination thresholds in the same experiments using randomly interleaved test locations. First‐order motion perception was examined by using moving stimuli embedded in static luminance contrast noise. Red/green (RG) and yellow/blue (YB) colour thresholds were measured with the Colour Assessment and Diagnosis (CAD) test, which makes use of random, dynamic luminance contrast noise (±45%) to isolate the use of RG and YB colour signals. Subjects were normal controls (n = 65) and glaucoma patients with binocular visual field defects (n = 15) classified based on their Humphrey Field Analyser mean deviation (MD) scores. The impairment of visual function varied depending on the stimulus attribute and location tested. The severity of loss increased monotonically with disease progression. For subjects with mild glaucoma (MD −0.01 to −6.00 dB), significantly more data points exceeded the upper normal threshold limits for the corresponding age for RG colour thresholds than for any other visual test (Br Med Bull 2017;122:51–77), followed by motion thresholds. This was particularly the case for the parafoveal locations when compared with the equivalent thresholds measured at the fovea. The results suggest that a multifaceted measure of binocular visual performance based on foveal and parafoveal tests of RG colour vision and first‐order motion, can best inform on the progression of glaucoma and the overall loss of visual performance for comparison with other measures of changes in the quality of life in patients with glaucoma.Keywords: Glaucoma, Visual function, Colour vision, Motion detection, Contrast, Acuity, Colour Assessment and Diagnosis, CAD.

Comparison of visual performance with iTrace analyzer following femtosecond laser-assisted cataract surgery with bilateral implantation of two different trifocal intraocular lenses.

To compare the postoperative binocular visual performance with an iTrace analyzer following femtosecond laser-assisted cataract surgery (FLACS) combined with bilateral implantation of two different types of diffractive trifocal intraocular lenses (IOL). During this retrospective observational study, patients who received bilateral FLACS combined with implantation of two different types of diffractive trifocal IOLs were evaluated. According to the IOLs' different types and design, the patients were divided into AT LISA tri839MP group (tri839 group) and AcrySof PanOptix TFNT00 group (TFNT group). Study parameters included preoperative and postoperative uncorrected distance visual acuity (UDVA) at 5 m, uncorrected near visual acuity (UNVA) at 30 cm and 40 cm, uncorrected intermediate visual acuity (UIVA) at 60 cm and 80 cm, postoperative refractive status, objective visual qualities and total high order aberrations (HOAs) postoperatively. The postoperative complications were also recorded. Totally 56 eyes of 28 patients (tri839 group, n=26; TFNT group, n=30) were included. Preoperative baseline characteristics between groups were not statistically significantly different. UDVA was not significantly different between groups except for 1wk follow-up due to the postoperative corneal edema. TFNT group showed statistically significant better UNIA at 60 cm than tri839 group at the 1wk (0.05±0.19 vs 0.15±0.10 logMAR, P=0.013), 1mo (0.05±0.12 vs 0.15±0.09 logMAR, P=0.001) and 3mo (0.04±0.12 vs 0.15±0.11 logMAR, P=0.001) follow-up, while tri839 group showed statistically significant better UNIA at 80 cm than TFNT group at the 1d (0.14±0.15 vs 0.20±0.14 logMAR, P=0.041) and 1mo (0.09±0.07 vs 0.14±0.10 logMAR, P=0.042) follow-up. Postoperative refractive status showed stable at every visit. Modulated transfer function (MTF) values and strehl ratio (SR) values were improved and HOAs were lower significantly after surgery. FLACS with bilateral implantations of both tri839 and TFNT00 can achieve satisfactory natural whole-course vision, high postoperative refractive stability and good visual quality but without significantly difference. iTrace aberration instrument can accurately evaluate the visual quality under different status.

Neural binocular summation and the effect of defocus on the pattern electroretinogram and visual evoked potentials for different pupil sizes.

To evaluate the influence of defocus and pupil size on subjective (visual acuity [VA]) and objective (electrophysiology) descriptors of human vision and their effect on binocular visual performance by means of neural binocular summation (BS). Fifteen healthy young subjects were recruited in this crossover study. Pattern electroretinogram (PERG) and visual evoked potentials (VEP) were measured under two levels of positive (+1.5 and +3.0 D) spherical and astigmatic defocus (axis 90°). Pupil size was controlled to reduce the inter-individual variability factor. Low- and high-contrast VA showed poorer visual performance in the monocular versus the binocular condition. Positive BS (for VA) was higher with greater pupil size and higher levels of defocus. In the visual electrophysiology tests (i.e., VEP and PERG), peak time and amplitude were affected by pupil size and defocus. The increase in peak time was larger and the reduction in amplitude was more significant with greater levels of defocus and smaller pupil sizes. For the VEP, positive BS was found in all conditions, being stronger with larger amounts of defocus and pupil size (for the P100 amplitude). Significant negative correlations were observed between the P100 amplitude and VA BSs. Smaller pupil size and levels of defocus produced greater changes in cortical activity as evidenced by both the PERG and VEP. Considering these changes and the obtained positive BS, the mechanism could be initiated as early as the retinal processing stage, then being modulated and enhanced along the visual pathway and within the visual cortex.

Influence of Interocular Differences and Alcohol Consumption on Binocular Visual Performance.

The purpose of this study was to assess the influence of a moderate breath-alcohol content (BrAC of 0.40 mg/L) on binocular visual performance for different visual functions after inducing different levels of interocular differences with the use of filters. A total of 26 healthy young subjects were enrolled. The participants participated in two sessions: one without alcohol consumption and another after alcohol consumption. In each session and for the different filter conditions (subjects were wearing Bangerter foil of 0.8 and BPM2 fog filter on the dominant eye), monocular and binocular visual function was evaluated by measuring visual acuity, contrast sensitivity, visual discrimination capacity (and successively by calculating their corresponding binocular summations) and stereopsis (near and distance stereoacuity). In addition, interocular differences were calculated for different retinal-image quality and straylight parameters. All monocular and binocular visual functions were analyzed and stereopsis was significantly impaired by alcohol and filters (p < 0.05). Interocular differences for different ocular parameters and binocular summations for visual parameters were negatively affected by filters but not alcohol. Significant correlations (averaging all the experimental conditions analyzed) were found, highlighting: the higher the interocular differences, the lower the binocular summation and the poorer the stereopsis and, therefore, the worse the binocular visual performance.

Enhanced Monofocal Versus Conventional Monofocal Intraocular Lens in Cataract Surgery: A Meta-analysis.

To compare different outcomes of an enhanced monofocal intraocular lens (IOL) versus a conventional monofocal IOL implantation after cataract surgery. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline was used for abstracting data and assessing quality. Comparative studies between enhanced monofocal versus conventional monofocal IOL implantations reporting outcomes in monocular and binocular visual acuities at various distances, spectacle independence, contrast sensitivity, optical quality, and adverse effects were identified from three databases. Meta-analysis, sensitivity analysis, and subgroup analysis were performed. A total of 680 eyes implanted with an enhanced monofocal IOL (Tecnis Eyhance ICB00; Johnson & Johnson) and 647 eyes with a conventional monofocal IOL from 3 randomized controlled trials and 9 comparative studies were included. The enhanced monofocal IOL showed better monocular uncorrected intermediate visual acuity (UIVA) (mean difference [MD]: -0.11 logMAR; 95% CI: -0.12 to -0.09), binocular UIVA (MD: -0.17 logMAR; 95% CI: -0.23 to -0.11), and binocular uncorrected near visual acuity performance (MD: -0.17 logMAR; 95% CI: -0.29 to -0.04) than the conventional monofocal IOL. More patients were spectacle free at intermediate distance with the enhanced monofocal IOL (odds ratio: 12.9; 95% CI: 6.2 to 27.0). Both monocular (MD: -0.002 logMAR; 95% CI: -0.01 to 0.01) and binocular (MD: 0.01 logMAR; 95% CI: -0.02 to 0.03) uncorrected distance visual acuity revealed non-significant differences between the IOL designs. Contrast sensitivity, photic phenomenon, and adverse effects were comparable. Enhanced monofocal IOLs effectively improved unaided intermediate vision with similar distance performance relative to conventional monofocal IOLs. This was achieved without compromising the contrast sensitivity or inducing photic phenomena. [J Refract Surg. 2022;38(8):538-546.].

Binocular Visual Function Changes After Corneal Collagen Cross-linking in Patients With Keratoconus.

High-order aberrations (HOAs) have been demonstrated to profoundly affect both visual acuity and stereoacuity in patients with keratoconus. Corneal collagen cross-linking (CXL) has been proven to significantly lower HOAs in keratoconus. Yet, to the present date, no evaluation of the effect of the procedure on stereopsis has been performed. The purpose of the study was to assess differences in binocular visual performance in patients with keratoconus before and after CXL. Patients with keratoconus undergoing standard Dresden protocol epi-off CXL in the ophthalmology department of Policlinico Universitario Agostino Gemelli Hospital received slitlamp examination, uncorrected distance visual acuity and corrected distance visual acuity assessment, corneal tomography, Lang stereotest, TNO stereoacuity assessment, distance and near cover test, and Irvine test before surgery and 6 months after CXL. Stereopsis tests were performed with spectacle correction. The analysis included 30 patients (mean age 24.63 ± 3.49 years). The Lang test improved after treatment ( P 0.027), with 6 of 30 patients (20%) showing a positive Lang test before CXL compared with 16 of 30 patients (53.3%) after treatment. Moreover, TNO stereoacuity increased after treatment ( P 0.043), and 14 of 30 patients (46.7%) manifested an improvement of at least 250″ at the TNO test after CXL. In this subgroup of patients, total root mean square values decreased after treatment ( P < 0.001), whereas patients who did not manifest a clinically significant improvement in stereoacuity did not show a reduction in total root mean square values after CXL ( P = 0.11). The results of cover test and Irvine test did not vary after CXL. Patients with keratoconus showing a reduction of HOAs after CXL also manifest a significant improvement in stereoacuity after the treatment.

Effect of interocular differences on binocular visual performance after inducing forward scattering

PurposeTo assess binocular visual performance by means of binocular summation on visual function after inducing monocular forward scattering, and to study the influence of interocular differences on ocular parameters.MethodsSeven young healthy subjects were recruited. Four Bangerter foils and five fog filters were used to induce monocular forward scattering. To analyse the impact of the scatter, visual acuity, contrast sensitivity, visual discrimination capacity and distance stereoacuity were measured binocularly with the filter placed over the dominant eye. Additionally, interocular differences were calculated for four ocular parameters: the Objective Scatter Index (OSI), Strehl ratio (SR), modulation transfer function cut‐off (MTF cut off) and straylight (log[s]). Binocular summation was determined for these visual functions.ResultsA statistically significant deterioration in visual acuity, contrast sensitivity and stereoacuity was seen for all of the filter conditions with respect to the natural state (baseline), with the largest change being recorded for the Bangerter foils. Similarly, the interocular difference for the three retinal image quality parameters (OSI, SR and MTF cut‐off) and log(s) increased significantly for the Bangerter foil condition, but not for the fog filters (except log(s)). Binocular summation declined gradually with the Bangerter foils, but not for the fog filters. Statistically significant correlations were found, that is, the greater the interocular differences, the lower the binocular summation of the visual functions and the greater the distance stereoacuity.ConclusionIncreased forward scattering in the dominant eye resulted in interocular differences, which reduced the overall binocular visual performance, including the binocular summation of several visual functions and distance stereoacuity. The results suggest that marked interocular differences in ocular parameters should be avoided in cases of ocular pathology, amblyopia and emmetropisation procedures (such as refractive surgery) or a monovision correction for presbyopia.

The influence of contact lenses with different optical designs on the binocular vision and visual behavior of young adults

Theoretically, contact lenses change the accommodation and vergence demands of the eyes and directly or indirectly influence binocular vision. The purpose of this study was to investigate the influence of different optical designs of contact lenses on binocular vision and visual behavior among young adults. In this randomized, single-blinded experimental study, visual behavioral performance (VBP) and Ocular Surface Disease Index questionnaires were used for preliminary screening. Nineteen myopic subjects aged 20–26 years (21.59 ± 1.40 years) participated in the study. Baseline values for subjective refraction and binocular visual functions were evaluated. All the subjects were randomly grouped to wear different optical designs of single-vision, progressive, and bifocal contact lenses. Eye examinations were performed on the first day (CL baseline), 2nd week, and 4th week of wearing the lenses. In addition, subjects completed the VBP and visual quality questionnaire again at the end of the examination. Single-vision contact lenses (Lens 1) increased accommodative lag, negative relative accommodation, and distant and near vergence; however, vergence facilities, accommodative facilities, heterophoria, and the comfort and posture balance dimensions in the VBP questionnaire were improved. Progressive contact lenses (Lens 2) reduced the lag of accommodation and near vergence; in addition, vergence facilities and accommodative facilities were also improved. Bifocal contact lenses (Lens 3) affected negative and positive relative accommodation, but vergence facilities and accommodative facilities also progressed. Furthermore, both progressive (Lens 2) and bifocal (Lens 3) contact lenses enhanced overall visual behavioral performance. In terms of visual quality, single-vision contact lenses (Lens 1) were the most comfortable, progressive and bifocal contact lenses reduced distant visual acuity and stability, progressive contact lenses (Lens 2) had more complaints about halos at night, and bifocal contact lens (Lens 3) users were more likely to have double vision. Compared with single-vision contact lenses, progressive and bifocal contact lenses relaxed accommodation, reduced the lag of accommodation, and improved visual behavioral performance. Although the vergence function showed a significant change, it did not show worse trends when wearing contact lenses. Contact lenses with different optical designs have a great influence on binocular vision and visual behavioral performance.

Binocular visual function and fixational control in patients with macular disease: A review.

For normally sighted observers, the centre of the macula—the fovea—provides the sharpest vision and serves as the reference point for the oculomotor system. Typically, healthy observers have precise oculomotor control and binocular visual performance that is superior to monocular performance. These functions are disturbed in patients with macular disease who lose foveal vision. An adaptation to central vision loss is the development of a preferred retinal locus (PRL) in the functional eccentric retina, which is determined with a fixation task during monocular viewing. Macular disease often affects the two eyes unequally, but its impact on binocular function and fixational control is poorly understood. Given that patients’ natural viewing condition is binocular, the aim of this article was to review current research on binocular visual function and fixational oculomotor control in macular disease. Our findings reveal that there is no overall binocular gain across a range of visual functions, although clear evidence exists for subgroups of patients who exhibit binocular summation or binocular inhibition, depending on the clinical characteristics of their two eyes. The monocular PRL of the better eye has different characteristics from that of the worse eye, but during binocular viewing the PRL of the better eye drives fixational control and may serve as the new reference position for the oculomotor system. We conclude that evaluating binocular function in patients with macular disease reveals important clinical aspects that otherwise cannot be determined solely from examining monocular functions, and can lead to better disease management and interventions.

Clinical Outcomes of Combined Implantation of an Extended Depth of Focus IOL and a Trifocal IOL in a Korean Population

Purpose To evaluate monocular and binocular visual performance and patient-reported outcomes following combined implantation of a diffractive extended depth of focus (EDoF) IOL (Carl Zeiss AT LARA 829MP) and a diffractive trifocal IOL (Carl Zeiss AT LISA tri 839MP). Methods This prospective study enrolled consecutive patients undergoing lens phacoemulsification of cataract and combined implantation of an EDoF IOL in the dominant eye and a trifocal IOL in the nondominant eye. Assessment included uncorrected visual acuity at near distances (UNVA), intermediate distances (UIVA), and far distances (UDVA), uncorrected defocus curve, contrast sensitivity (CS), reading speed, and patient satisfaction, evaluated six months after the surgery with the Visual Function Questionnaire (VFQ-25). Results A total of 25 patients were enrolled. At six months postoperatively, outcomes of binocular UNVA, UIVA, and UDVA were superior to those of monocular outcomes. The binocular defocus curve showed significantly better results in comparison with the AT LISA tri IOL eyes at defocus levels of −1.0 D and −1.5 D (P=0.008 and P=0.002, respectively) and compared to the AT LARA IOL eyes at defocus levels of −3.0, −3.5 D, and −4.0 D (P=0.019, P=0.019, and P=0.035, respectively). All of the patients were spectacle-free at far and intermediate distances, while 4% of patients needed spectacles at the near distance. Reading speed showed a rather high and gentle slope curve between 0.1 logMAR and 0.4 logMAR, and optical phenomena were improved after combined implantation of IOLs except halos. There were no significant differences in CS between the binocular and monocular results of each IOL. Conclusions The combined implantation of an EDoF IOL and a trifocal IOL seems to be a good option for patients with demands for spectacle independence in their daily life, with minimal photic phenomena.

Clinical outcomes with a low add multifocal and an extended depth of focus intraocular lenses both implanted with mini-monovision.

To compare the visual acuity, contrast sensitivity (CS), spectacle needs, photic phenomena, and quality of life parameters of patients bilaterally implanted with a low add multifocal (MIOL) or an extended depth of focus (EDOF) intraocular lens (IOL), both with intended mini-monovision. In this prospective, randomized, comparative study, patients were randomized to receive either Tecnis +2.75 D (ZKB00) (MIOL Group, n = 15) or Tecnis Symfony (ZXR00) (EDOF Group, n = 14) for bilateral implantation with mini-monovision (-0.50 D). Binocular logMAR uncorrected visual acuities (UVA), monocular defocus curves, CS with CSV 1000-E, and Pelli-Robson Test (PRT), spectacle needs and quality of life parameters with NEI RQL-42 questionnaire were evaluated at postoperative 1, 3, and 6 months. Results of MIOL and EDOF Groups at postoperative month 6 are as follows: distance (6 m) UVA -0.03 ± 0.05 and -0.05 ± 0.06 (p = 0.938), intermediate (60 cm) UVA, 0.04 ± 0.08 and -0.03 ± 0.07 (p = 0.046); near (40 cm) UVA, 0.22 ± 0.08 and 0.15 ± 0.07 (p = 0.046); near spectacle needs, 26.7% and 14.3% (p > 0.05), respectively. Better visual acuity was achieved in the EDOF Group between the defocus range of -0.50 and -1.75 D (p < 0.05). No significant difference was found regarding photic phenomena and CS evaluated with CSV 1000-E between the two IOL groups at 6 months after surgery (otherwise there are differences at 1 and 3 months in favor of EDOF). However, EDOF Group performed better in mesopic CS evaluated with PRT (p < 0.05). When implanted with mini-monovision better binocular uncorrected visual performance at intermediate and near distances achieved with EDOF than low add MIOL.

Deterioration of binocular vision after alcohol intake influences driving performance

In this study, we assessed the influence of moderate alcohol intake on binocular vision, vergence system and simulated driving performance by analyzing the interactions between visual deterioration and driving variables. Thirty young healthy subjects were recruited. For the analysis, we measured: visual function (visual acuity and stereoacuity), phorias and fusional reserves. Also, we checked Sheard’s and Percival’s criteria at near and far. The accommodative convergence/accommodation (AC/A) ratio was calculated and vergence facility was also obtained at near. A driving simulator was used to assess driving performance under natural conditions and after alcohol consumption with a breath alcohol content of 0.40 mg/l. Alcohol intake significantly reduced binocular visual performance and vergence function, except for vertical phorias, horizontal phoria at near and Sheard’s and Percival’s criteria at near. Driving performance parameters also presented a statistically significant deterioration after alcohol consumption. A statistically significant correlation was found between the deterioration in overall visual function and overall driving performance, highlighting the influence of the visual deterioration on the driving performance. Moderate alcohol consumption impairs binocular visual and simulated driving performances, implying a greater safety hazard. In addition, deteriorations in binocular visual function and vergence correlated with simulated driving impairment, which indicates that the deterioration of binocular vision due to alcohol consumption affects driving, thus reducing road safety.

Grey Filter Contact Lens as Therapeutic Option for Acquired Reduced Binocular Visual Performance.

Disturbing binocular problems can be too complex to be treated in such a way that comfortable binocular single vision is restored. The grey filter contact lens could offer a safe and clinically useful way to help these patients.Background:In unilateral acquired reduced visual performance or intractable diplopia the binocular performance often is less than the performance of the better eye, possibly leading to complaints of binocular visual functioning. The hypothesis is to use a grey filter contact lens on the affected eye to obtain more binocular visual comfort. The grey filter changes the binocular central visual image in the brain through delaying the image of the affected eye and has minimal effect on the peripheral vision. The purpose of this study was to evaluate the effect of the grey filter contact lens on the reduction of patients’ binocular complaints in daily life.Methods:In 19 consecutive patients with unilateral acquired reduced visual performance or intractable diplopia a grey filter contact lens was fitted. The contact lens was chosen from six available filters with different transmissions, based on patient preference. The chosen filter contact lens was fitted according to the normal practice of contact lens fitting.Results:The results of 18 patients are reported, one patient was lost to follow-up. Twelve patients (67%) reported good results when wearing the grey filter contact lens. Five patients (28%) discontinued wear of the grey filter contact lens because their binocular visual complaints disappeared during filter contact lens wear and remained absent after contact lens wear was terminated.Conclusion:The grey filter contact lens is a clinically useful, safe, and easily reversible treatment option for patients with binocular visual complaints due to an acquired monocular reduction in visual quality.

Longitudinal Changes in Optical Quality, Spatial Vision, and Depth Vision after Laser Refractive Surgery for Myopia.

Laser refractive surgery procedures are efficacious at correcting myopia, but they result in long-term deterioration of optical quality that affects monocular and binocular visual performance. The study shows that the optical quality of the two eyes needs to be similar to optimize binocular visual performance after surgery. This study aimed to systematically analyze longitudinal changes in optical quality, high- and low-contrast logMAR acuity and random-dot stereoacuity before and after three refractive surgery procedures for correcting myopia. A total of 106 subjects (laser-assisted in situ keratomileusis, 40; photorefractive keratectomy, 26; small-incision lenticule extraction, 40) with myopia and astigmatism ≤1.5 D participated in this prospective cohort-based study. All aforementioned outcome variables were measured in both eyes pre-operatively and 1 week and 1, 3, and 6 months post-operatively. Pre-operative myopic spherical equivalent of refraction (median [25th to 75th interquartile range], -6.4 D [-8.0 to -4.2 D] for laser-assisted in situ keratomileusis, -4.3 D [-5.0 to -3.5 D] for photorefractive keratectomy, -5.5 D [-6.5 to -4.3 D] for small-incision lenticule extraction) was corrected to within ±0.75 D of emmetropia in all cohorts up to 6 months post-operatively (P < .001). Higher-order wavefront aberrations, uncorrected high- and low-contrast logMAR acuity, and stereoacuity all worsened and remained so up to 6 months post-operatively, relative to pre-operative values (P < .001). Stereoacuity worsened with both interocular average and difference in the magnitude of higher-order aberrations, whereas logMAR acuities worsened only with interocular average of these aberrations (r ≥ 0.40; P < .01 for all). Although the refractive surgery procedures tested here correct myopia, they result in a sustained (up to 6 months) loss of optical quality and spatial and depth-related visual functions post-operatively. Both interocular average and difference in the eye's optical quality seem to impair binocular visual functions after refractive surgery for myopia.

The Effect of Wearing ChromaGen Lens II on Visual Stress, Binocular Visual Functions and Reading Performance in Children with Dyslexia

The Effect of Wearing ChromaGen Lens II on Visual Stress, Binocular Visual Functions and Reading Performance in Children with Dyslexia

Evaluation of visual evoked potential binocular summation after corneal refractive surgery.

To explore whether visual evoked binocular summation is affected in eyes with refractive errors after refractive surgery. Twenty participants (6M, 14F) aged 20-35years (mean 26.7 ± 4.4) were assessed through pattern-reversal visual evoked potential viewing with their every eye (first right eye and then left eye) and then with both eyes while wearing their best correction before undergoing surgery. Also, parameters of the P100 component of pattern-reversal visual evoked potential were evaluated after 3months of refractive surgery in two different check sizes. Monocular and binocular amplitudes and latencies of P100 wave and binocular summation index were compared between before and after surgery. Monocular visual evoked potentials elicited by two different high-contrast checkerboard-patterned stimuli were significantly reduced in P100 wave amplitude (P < 0.05) after refractive surgery. However, there was no difference between the pre- and post-refractive surgery in the mean value of monocular P100 latency (P > 0.05). Similar to monocular findings of P100 wave amplitude, on binocular viewing, the mean value of pattern-reversal visual evoked potential amplitude was significantly reduced (P < 0.05), and P100 wave latency was prolonged (P < 0.05) after refractive surgery in participants. Also, the mean postoperative binocular summation index value as compared to that in the preoperative was significantly lesser (P < 0.05) for the subject in this study. Refractive surgery can degrade binocular visual performance throughout the change in visual evoked potential binocular summation. However, monocular function deteriorates less than binocular function after refractive surgery.

Visual system disorders and musculoskeletal neck complaints: a systematic review and meta-analysis.

Accommodation disorders and nonstrabismic binocular dysfunctions affect patients' binocular system and visual performance. These visual disorders could be associated with musculoskeletal discomfort in the neck and shoulder area. The purpose of this systematic review and meta-analysis was to ascertain the relationship between visual system disorders and the musculoskeletal system of the neck. The review protocol is available in PROSPERO (CRD42018112771). All articles selected examined the relationship between neck conditions (chronic neck pain and whiplash) and the visual system in adult populations. Studies with optometric or physiotherapeutic measurements were included. Bias risk was evaluated with the modified Cochrane Collaboration Tool and Study Quality Assessment Tool. To provide complete quality assessment evidence, the authors applied the GRADEpro Guideline Development Tool. The literature search was conducted in November 2018 and yielded 745 studies among all the databases. Out of these studies, 21 were finally included. Most of the studies presented a moderate methodological quality. Only one high-quality trial was found. Based on a qualitative assessment, our systematic review and meta-analysis revealed that all included studies established a relationship between the visual system and musculoskeletal system of the neck. However, the methods for the measurement of the visual system lacked uniformity.

Wavefront-Guided Versus Wavefront-Optimized Photorefractive Keratectomy: Visual and Military Task Performance.

To compare visual performance, marksmanship performance, and threshold target identification following wavefront-guided (WFG) versus wavefront-optimized (WFO) photorefractive keratectomy (PRK). In this prospective, randomized clinical trial, active duty U.S. military Soldiers, age 21 or over, electing to undergo PRK were randomized to undergo WFG (n = 27) or WFO (n = 27) PRK for myopia or myopic astigmatism. Binocular visual performance was assessed preoperatively and 1, 3, and 6 months postoperatively: Super Vision Test high contrast, Super Vision Test contrast sensitivity (CS), and 25% contrast acuity with night vision goggle filter. CS function was generated testing at five spatial frequencies. Marksmanship performance in low light conditions was evaluated in a firing tunnel. Target detection and identification performance was tested for probability of identification of varying target sets and probability of detection of humans in cluttered environments. Visual performance, CS function, marksmanship, and threshold target identification demonstrated no statistically significant differences over time between the two treatments. Exploratory regression analysis of firing range tasks at 6 months showed no significant differences or correlations between procedures. Regression analysis of vehicle and handheld probability of identification showed a significant association with pretreatment performance. Both WFG and WFO PRK results translate to excellent and comparable visual and military performance.

Binocular summation and visual function with induced anisocoria and monovision.

The advances in new techniques for correcting presbyopia, such as a small aperture combined with monovision, require an in-depth study of binocular aspects. In this work, we have studied binocular visual performance of 12 subjects after inducing different degrees of anisocoria combined with two different add powers in the non-dominant eye. We have analysed visual performance in terms of the visual-discrimination capacity (a function to evaluate the strength of bothersome halos) and the contrast-sensitivity. The results show a deterioration of the binocular vision when inducing anisocoria and with any add power, with a higher perception of halos, a lower contrast sensitivity and poorer binocular summation of these visual functions on increasing anisocoria. This deterioration is clinically acceptable in the case of low add power, since positive binocular summation is maintained in contrast sensitivity, and visual discrimination is not altered.