Comparison of visual outcomes with implantation of trifocal versus bifocal intraocular lens after phacoemulsification: a Meta-analysis

AIM： To compare a trifocal intraocular lens （IOL） and a bifocal IOL implantation in improving visual function after cataract surgery. METHODS： Eligible literatures were systematically searched through EMBASE and PubMed databases. The inclusion criteria were prospective comparative clinical trials on cataract surgery comparing trifocal IOL with bifocal IOL implantation that assessed visual acuity, contrast sensitivity and subjective vision quality. The effects were computed as standardized mean differences and pooled using fixed-effect or random-effect models. RESULTS： Four prospective randomized controlled trials （RCTs） and five cohorts provided data were included by a systematic review, comprising 265 eyes implanted with trifocal IOLs and 264 eyes implanted with bifocal IOLs. Monocular distance visual acuity （VA） showed a statistically significant but small difference that favored trifocal IOLs （MD=.0.06; 95%CI, -0.10 to -0.02; Z=2.90, P=0.004 for uncorrected distance VA, and MD- -0.02; 95%CI, -0.03 to .0.00; Z=2.02, P=0.04 for corrected distance VA）, but the data did not suggest that the effect of trifocal IOL implantation would clinically outperform bifocal IOL implantation. There was no significant difference in monocular near VA （MD=.0.01; 95%CI, -0.07 to 0.04; Z=0.42, P=-0.68 for distance-corrected near VA, and MD=-0.01; 95%CI, -0.06 to 0.03; Z=0.55, P=0.58 for corrected near VA） or refraction between two groups. Contrast sensitivity and subjective visual quality had no conclusive results. CONCLUSION： All results indicate that trifocal IOL and bifocal IOL had similar levels of monocular distance and near VA.

Postoperative visual performance with a bifocal and trifocal diffractive intraocular lens during a 1-year follow-up

AIM：To evaluate and compare the clinical outcomes with a diffractive bifocal and trifocal intraocular lens（IOL）during a 12-month follow-up.METHODS：Prospective comparative study including75 eyes of 38 patients（44-70y）undergoing uneventful cataract surgery.Each patient was randomly assigned to one type of IOL,bifocal（35 eyes）or trifocal（40 eyes）.Visual,refractive,and contrast sensitivity changes were evaluated in a 12-month follow-up.The binocular defocus curve was also measured at 12mo postoperatively.RESULTS：No statistically significant differences between groups were found in postoperative uncorrected and corrected distance visual acuities（P≥0.276）.Postoperative corrected near visual acuity（33 cm）was significantly better in the trifocal group during all follow-up（P≤0.004）as well as 6-month uncorrected near（P=0.008）and distancecorrected near visual acuities（P=0.016）（33/40 cm）.Significantly better uncorrected intermediate and distance corrected-intermediate visual acuity were found during all follow-up in the trifocal group（P〈0.001）,which was consistent with differences among groups in binocular defocus curve.Differences among groups in contrast sensitivity were minimal,being only significant at 6 months for some low to medium spatial frequencies（P≤0.006）.CONCLUSION：Bifocal and trifocal diffractive IOLs are able to provide an effective visual restoration which is maintained during a 12-month follow-up,with a clear benefit of the trifocal IOL for the intermediate vision.

Rainbow halos occur less following implantation of extended range of vision one-piece intraocular lenses vs diffractive bifocal intraocular lenses

AIM:To evaluate clinical outcomes following implantation of an extended range of vision intraocular lens(IOL),the ZXR00,and a diffractive multifocal IOL with+2.75 diopters(D)add power,the ZKB00.METHODS:Totally 30 patients who underwent either bilateral implantation of the ZXR00 IOL with intended emmetropia(ZXR00 emmetropia group:20 eyes)and intended micromonovision(ZXR00 monovision group:20 eyes),or bilateral implantation of the ZKB00 IOL with intended emmetropia(ZKB00 group:20 eyes)were included in this study.Visual acuity at 4 m,80,and 40 cm;and the types of halos(misty,fine,and rainbow)were analyzed at one and three months after surgery.RESULTS:There were no significant differences in distance visual acuity among the three groups.The mean uncorrected intermediate visual acuity was better in the ZXR00 emmetropia and monovision groups(0.02 logMAR and 0.02 logMAR,respectively)than in the ZKB00 group(0.14 logMAR).The mean uncorrected near visual acuity was worse in the ZXR00 emmetropia group(0.26 logMAR)than in the ZXR00 monovision and ZKB00 groups(0.12 logMAR and 0.10 logMAR,respectively).There was an increased incidence of rainbow halos in the ZKB00 group vs in either ZXR00 group(P=0.033).CONCLUSION:Implantation of the ZXR00 IOL with intended micromonovision provide superior visual acuity than implantation of the ZXR00 IOL with intended emmetropia.The ZXR00 IOLs tend to show a lower incidence of rainbow halos than did the ZKB00 IOL.

Residual Astigmatism Threshold and Patient Satisfaction with Bifocal, Trifocal and Extended Range of Vision Intraocular Lenses (IOLs)

Purpose: To compare the impact of induced astigmatism with four different types of multifocal intraocular lenses (MIOLs). Method: Prospective, comparative, interventional, mono-centered study, including 80 eyes of patients with implantation of four different MIOLs: AcrySof ReSTOR +2.5 D (20 eyes), AcrySof ReSTOR +3.0 D (20 eyes), AcrySof Panoptix (20 eyes) (Alcon Laboratories, Inc., Fort Worth, TX, USA), and Tecnis Symfony ZRX00 (Abbott Medical Optics, Santa Ana, USA) (20 eyes). Patients were followed up for 3 months after surgery. Major parameters were uncorrected (UDVA) and corrected (CDVA) distance visual acuity, subjective refraction and patient satisfaction. Results: Differences between IOLs with regard to the impact of the cylinder sign and axis on visual acuity and patient satisfaction were not significant. With mild added negative cylinder, AcrySof ReSTOR +2.5 D and Tecnis Symfony IOLs maintained the baseline visual acuity, while it was mildly reduced with AcrySof ReSTOR +3.0 D and Panoptix IOLs. With moderate induced cylinder, the Tecnis Symfony IOL maintained good visual acuity and patient associated satisfaction. Panoptix IOL was the IOL most affected by the induced astigmatism with regard to dissatisfaction and visual acuity. The highest tolerance to the astigmatic distortion and blurriness induced with a -1.50 D cylinder was obtained with the Tecnis Symfony IOL. Tecnis Symfony IOL showed less dissatisfaction and less reduction of visual acuity than the other MIOLs. Conclusion: Simulated residual cylinders after the implantation of the Tecnis Symfony IOL up to 1.0 D have a very mild and not clinically relevant impact on visual acuity or patient satisfaction. The ERV IOL showed a better tolerance to unexpected postoperative residual errors than diffractive bifocal and trifocal IOLs.

Spasm of the near reflex:a common diagnostic dilemma?

AIM:To report the clinical characteristics and diagnostic procedures used in patients with spasm of the near reflex(SNR),in order to present common investigation strategies and diagnostic pitfalls.METHODS:Retrospective case series of twenty-two patients,mainly children,with SNR or accommodation spasm(AS).AS was diagnosed on the basis of blurred vision and a difference of>2 dioptres between manifest and cycloplegic retinoscopy.If esotropia and miosis were present,the patients were diagnosed with SNR.All patients underwent visual acuity testing,orthoptic evaluation,assessment of refraction before and after cycloplegia,and dilated fundoscopy.Additional diagnostic investigations,such as neuroimaging,lumbar puncture(LP),electrophysiology and blood tests,were also recorded.Screen use among children was assessed in hours per day.RESULTS:There were 19 female and 3 male patients(age range 7-33 y,median=10 y).Seventeen patients had AS and 5 patients had SNR,with episodic blurry vision and headaches being the most common symptoms.Brain neuroimaging was performed in six patients(27%),although only one had a history of brain trauma.Two of those patients underwent visual evoked potentials and three also underwent LP and received intravenous steroid therapy.The majority of patients(90%)reported prolonged daily screen time(>2 h/d),and in 55%of cases there were concurrent social problems or psychological triggers.Treatment consisted of careful explanation of the condition,atropine1%eye drops and full cycloplegic correction by means of bifocal glasses.CONCLUSION:The diagnosis of SNR and AS may be challenging,because symptoms are usually intermittent and nonspecific,and a large number of patients are often subjected to redundant and potentially time-consuming examinations and treatment,that may exaggerate the underlying psychological disorder.Hence,detailed clinical testing and assessment of psychosocial profile is necessary,in order to avoid unnecessary investigations.Neuroimaging should be performed only in selected cases.Finally,due to prolonged screen use SNR and AS may become more frequent in the future.

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

AIM:To investigate and compare the quality of life,satisfaction,contrast sensitivity,glare,depth perception,and intraocular lens(IOL)rotation in patients who underwent trifocal toric and bifocal toric IOLs.METHODS:A total of 80 eyes of 40 patients were included in this prospective study.Twenty patients in each group were implanted with trifocal toric and bifocal toric IOL,respectively.Preoperative and postoperative 6-month measurements were recorded for both patient groups.Comprehensive anterior and posterior segment examinations,distance-intermediate-near visual acuity values and the visual function scale questionnaire results were evaluated at these examinations.Patient satisfaction,contrast sensitivity,glare,intermediate-near and distance stereopsis and IOL rotation were also evaluated.RESULTS:No significant difference was found between the groups in terms of distance and near visual acuities(P=0.269,P=0.451).Intermediate visual acuity was significantly increased in the trifocal toric group(P<0.001).The visual function scale results were increased after surgery in both groups(P=0.001 and P<0.001),with no difference determined between them(P=0.158 and P=0.691).The number of patients wearing glasses was low in both groups and there was no significant difference between the groups(P>0.05).The overall satisfaction in the trifocal toric group was significantly higher than in the bifocal toric group(P=0.03).The highest sensitivity was observed at 6 cpd spatial frequency in all patients under photopic conditions(1.80±0.24 logU,1.74±0.20 logU).Distance-intermediate-near binocular depth perception results in both groups were higher in the trifocal toric group(P=0.02,0.048,0.003,respectively).Although there was no significant difference for 3 meters stereopsis,the trifocal toric group had higher depth perception(P=0.577).Mean rotation was 5.76°±3.93°in the trifocal toric group and 12°±7.1°in the bifocal toric group.CONCLUSION:Better results in the middle distance are obtained in the trifocal toric group and less IOL rotation due to digital system-coordinated surgery.Moreover,the overall satisfaction in the trifocal toric group is significantly higher than in the bifocal toric group.

Multifocal and extended depth of focus intraocular lenses

Advances in intraocular lens(IOL)design have rendered cataract surgery a refractive procedure.Newer IOL types include bifocal,trifocal and extended depth of focus(EDOF)IOLs.Their basic difference nestles in the number of focal points that each lens provides,which in turn leads to different visual outcomes.Familiarity of surgeons with the various characteristics of each lens is of utmost importance for accurate IOL selection to match each patient’s needs.In this review,we aim to compare the clinical outcomes after implantation of multifocal and EDOF IOLs in terms of distance,intermediate and near vision,contrast sensitivity,and reading performance.Finally,we discuss the defocus curve and the optical and photic phenomena associated with each type of IOL.

Bilocal Derivations of Reflexive Algebras

Let A be a reflexive algebra in reflexive Banach space X such that both O+ ≠O and X_ ≠ X in LatA, then the set of all derivations of A into B(X) is topologically algebraically bireflexive.

Independent phase manipulation of co-and cross-polarizations with all-dielectric metasurface

Phase carried by two orthogonal polarizations can be manipulated independently by controlling both the geometric size and orientation of the dielectric nanopost.With this characteristic,we demonstrate a novel multifunctional metasurface,which converts part of the incident linearly polarized light into its cross-polarization and encodes the phase of the two orthogonal polarizations independently.A beam splitter and a bifocal metalens were realized in a single-layer dielectric metasurface by this approach.We fabricated the bifocal metalens and demonstrated that two focal spots in orthogonal polarizations can be separated transversely or longitudinally at will.The proposed approach shows a new route to design multifunctional metasurfaces with various applications in holography and three-dimensional display.

Three-dimensional tracking of multiple particles in large depth of field using dual-objective bifocal plane imaging

Tracking moving particles in cells by single particle tracking is an important optical approach widely used in biological research. In order to track multiple particles within a whole cell simultaneously, a parallel tracking approach with large depth of field was put forward. It was based on distorted grating and dual-objective bifocal imaging, making use of the distorted grating to expand the depth of field, dual-objective to gather as many photons as possible, and bifocal plane imaging to realize three-dimensional localization. Simulation of parallel tracking of two particles moving along the z axis demonstrated that even when the two are axially separated by10 μm, they can both be localized simultaneously with transversal precision better than 5 nm and axial precision better than 20 nm.

Bifocal-Lens Converging Based OAM Wireless Communications

Orbital angular momentum(OAM)based radio vortex wireless communications have received much attention recently because it can significantly increase the spectrum efficiency.The uniform circular array(UCA)is a simple antenna structure for high spectrum efficiency radio vortex wireless communications.How-ever,the OAM based electromagnetic waves are vortically hollow and divergent,which may result in the signal loss.Moreover,the divergence of corresponding OAM based electromagnetic wave increases as the order of OAM-mode increases.Therefore,it is difficult to use high-order OAM-mode,because the corresponding received signal-to-noise ratio(SNR)is very small.To overcome the difficulty of high-order OAM modes transmission,in this paper we propose a lens antenna based electromagnetic waves converging scheme,which maintains the angular identification of multiple OAM-modes for radio vortex wireless communications.We further develop a bifocal lens antenna to not only converge the electromagnetic wave,but also compensate the SNR loss on traditional electromagnetic waves.Simulation results show that the proposed bifocal lens can converge the OAM waves into cylinder-like beams,providing an efficient way to in-crease the spectrum efficiency of wireless communications.