Development of a novel multifocal lens using a polarization directed flat lens: possible candidate for a multifocal intraocular lens

Background A polarization-directed flat (PDF) lens acts as a converging lens with a focal length (f) > 0 and a diverging lens with f < 0, depending on the polarization state of the incidental light. To produce a multifocal lens with two focal lengths, a PDF and a converging lens having shorter focal length were combined. In this study, we tested a bifocal PDF to determine its potential as a new multifocal intraocular lens (IOL). Methods Constructed a multifocal lens with a PDF lens (f = +/− 100 mm) and a converging lens (f = + 25 mm). In an optical bench test, we measured the defocus curve to test the multifocal function. The multifocal function and optical quality of the lens in various situations were tested. An Early Treatment Diabetic Retinopathy Study (ETDRS) chart as a near target and a building as a distant target were photographed using a digital single-lens reflex (DSLR) camera. Both lenses (multifocal and monofocal) were tested under the same conditions. Results For the 0 D and − 20 D focal points, the multifocal lens showed sharp images in the optical bench test. In the DSLR test using the multifocal lens, the building appeared slightly blurry compared with the results using the monofocal lens. With the multifocal lens, the ETDRS chart’s images became blurry as the ETDRS chart’s distance decreased, but became very clear again at a certain position. Conclusions We confirmed the multifocal function of the multifocal lens using a PDF lens. This lens can be used as a multifocal IOL in the future.

Quantitative assessment of photic phenomena in the presbyopia-correcting intraocular lens

This was a prospective study to evaluate the feasibility of the photic phenomena test (PPT) for quantifying glare, halo, and starburst. We compared two presbyopia-correcting intraocular lenses (IOLs), the Symfony IOL and the PanOptix IOL, as well as the monofocal Clareon IOL in 111 IOL-implanted eyes of 111 patients who underwent the PPT 1 month postoperatively. The reproducibility of photic phenomena with the PPT was assessed in 39 multifocal IOL-implanted eyes of 20 patients and among the examiners. Patients with ocular diseases, except for refractive errors, were excluded. The mean values of the groups were evaluated. Bland–Altman plots were used to analyze statistical data (Easy R version 1.37; R Foundation for Statistical Computing, Vienna, Austria). The PPT reproducibility assessment revealed no fixed bias or regressive significance. Reproducibility was confirmed. The glare size did not differ significantly between the Symfony, PanOptix, and Clareon groups. The halo size was significantly larger in the Symfony group (p < 0.01) than in the PanOptix group. The halo intensity was significantly brighter in the PanOptix group (p < 0.01) than in the Symfony group. In contrast, no halos were perceived in the Clareon group. The starburst size or intensity did not differ significantly between the Symfony, PanOptix, and Clareon groups. We identified the photic phenomenon related to various IOLs.

Expectations and Reality in Surgical Rehabilitation of Cataract Patients

The aim. To study the effect of surgical treatment of cataracts on the quality of life of patients and assess satisfaction with the results after implantation of a monofocal or multifocal intraocular lens (IOL), depending on the initial refraction. Materials and methods. We examined 140 patients (280 eyes) who underwent phacoemulsification with IOL (bilateral) according to the standard technique using multimodal anesthesia. The observation groups were divided depending on the initial type of refraction and the type of intraocular correction (mono- or multifocal IOL). The analysis of the results of surgical treatment of cataracts with IOL was assessed taking into account the initial refraction according to objective data, i.e. determination of distance and near visual acuity, and subjective data, i.e. the NEI-VFQ-25 quality of life questionnaire, patient questionnaire survey and assessment of the quality of vision in general, as well as distance, near, and night vision. Results and discussion. Before surgery, the mean values of indicators by all scales of the questionnaire of the quality of life related to the quality of vision ranged from 40 to 60 points and averaged 47 ± 0.5 points. After cataract surgery, the numerical indicator by each of the scales shifted to the range of 85 to 100 points. The difference in values by the scales “activity associated with distance vision” and “driving a car” was obtained. In patients with multifocal IOL, these indicators were lower compared with monofocal implantation. Dissatisfaction with distance vision was observed during the implantation of a multifocal IOL only in patients with hyperopia (12.5%), dissatisfaction with near vision was noted only in patients with myopia (16.7%), and no cases of dissatisfaction were observed in the group of patients with emmetropia. Analysis of night vision in patients with emmetropia also revealed the minimum percentage (2.5%) of cases of dissatisfaction in patients with hyperopia (5.0%) and the maximum in those with myopia (16.7%). Conclusions. IOL implantation is a single cataract treatment option that provides a high level of the patient’s satisfaction with the quality of life and visual functions. However, careful individual approach is required to select the type of implantable IOL, taking into account the patient’s needs and baseline refraction.

Analys of multifocal and toric extended depth of focus intraocular lenses implantation

Purpose. Analysis of the functional results of new IOL with an extended depth of focus implantation a in the short-term (6 months) follow-up period. Material and methods. The prospective study included 27 patients (40 eyes) after bilateral (n=12) or monolateral (n=15) implantation of EDOF IOL Tecnis Symfony with an average follow-up period of 6.5±0.2 (6-7) months. In all cases, IOL implantation was preceded by cataract phacoemulsification or removal of the transparent lens for refractive purposes. The age range was from 39 to 78 (60.6±10.1) years. EDOF IOL Tecnis Symfony ZXR00 was implanted in 30 eyes, and toric EDOF IOL Tecnis Symfony ZXT100, ZXT150, ZTX225, and ZXT300 were implanted in 10 eyes in the presence of clinically significant astigmatism. Results. An increase in UCNVA from 0.18±0.04 to 0.79±0.11, UCIVA from 0.21±0.07 to 0.89±0.10, UCDVA from 0.24±0.06 to 0.95±0.16, BCNVA from 0.61±0.05 to 0.80±0.03, BCIVA from 0.58±0.10 to 0.97±0.19, and BCDVA from 0.65±0.08 to 1.0±0.06 (p<0.05 in all cases). The spherical equivalent of refraction decreased from -4.5±1.8 in the preoperative period to -0.18±0.92 in the follow-up period of 6 months after implantation of the Tecnis Symfony ZXR00 IOL. In the group with toric IOLs, a decrease in the cylindrical component of refraction was shown from 1.33±1.02 (modulo) to 0.61±0.44 (modulo) during the maximum observation period. In all cases, the rotational stability of the implanted IOLs was noted. In 9 patients out of 24 (37.5%), permanent or periodic optical phenomena were detected, of which 4 patients (16.7%) had halos, 3 (12.5%) had glare, and 2 (8.3%) had difficulty driving in the dark. These side effects did not affect the overall patient satisfaction – 22 patients (91.7%) rated the result of the operation as "excellent", and 2 patients (8.3%) – as "good". Conclusion. The paper presents an analysis of the first experience in the Russian Federation of implantation of new multifocal and toric IOLs with extended depth of focus in 27 patients. Data on the effectiveness of this IOL for vision correction at all distances, low frequency of side optical phenomena, and high patient satisfaction are presented. Further comparative studies with other multifocal IOLs are needed. Key words: cataract; presbyopia; multifocal IOL; IOL with extended depth of focus; EDOF; Symphony.

Tactics of Two-Stage IOL Implantation in Difficult Refractive Cases

In a number of complex refractive cases, the achievement of an accurate refractive result cannot be guaranteed. Simultaneous implantation of a toric or multifocal IOL for the correction of complex ametropias may be accompanied by a significant deviation from the target refraction. The tactics of two-stage implantation with the usage of an additional Sulcoflex IOL for the final correction of astigmatism and possible residual spherical ametropia allows achieving emmetropia. In our study, this method was used in 15 patients with difficult refractive cases. Toric, multifocal, and multifocal toric Sulcoflex IOL were used. Implantation of all Sulcoflex modifications was performed through a 2.4 mm temporal incision using wound assisted technology. In cases of high degree hypermetropia, preventive iridectomy was performed using a 23G vitrectome. The target refraction was achieved in the entire observation group. In the postoperative period, no significant level of ophthalmic hypertension was registered. No cases of introlens opacification, iridocyclitis, or rotational instability were registered either.The method of two-stage IOL implantation allows achieving the target refraction in difficult refractive situations with almost guaranteed accuracy. The calculation method provides good predictability of the refractive result. This technology significantly expands the indications for intraocular correction using toric and multifocal IOL, as well as the limits of correction of high degree astigmatism. Our Sulcoflex IOL implantation experience has shown their high efficiency and safety.

Two Different Corneal Incision Designs for Correcting Corneal Astigmatism During Cataract Surgery With Multifocal Intraocular Lens Implantation

Background: Multifocal intraocular lenses (IOLs) is very intolerant to residual corneal astigmatism and patients with more than 1.0 D of residual corneal astigmatism are not suitable candidates for implantation of multifocal IOLs. The purpose of this study was to evaluate the efficacy of a single clear corneal incision (CCI) or an opposite clear corneal incision (OCCI) made on a steep meridian for correction of low to moderate corneal astigmatism during implantation of multifocal IOLs.Methods: This is a retrospective cohort study. A total of 80 patients with pre-operative total corneal astigmatism, ranging between 0.5 and 2.0 diopters (D), who underwent cataract surgery and received multifocal IOLs were included. Correction of corneal astigmatism was done via single CCIs on steep meridians in patients with 0.5–1.2 D total corneal astigmatisms, and OCCIs in patients with 1.3–2.0 D total corneal astigmatisms. Visual acuity, corneal astigmatism, ocular aberrations, corneal aberrations, and subjective vision quality were evaluated after surgery.Results: At 12-weeks post-surgery, the mean uncorrected distance vision acuity (UDVA) was 0.06±0.09 logarithm of the minimum angle of resolution (logMAR) and 0.03±0.09 logMAR, and the mean uncorrected near vision acuity(UNVA) was 0.08±0.11 logMAR and 0.09±0.09 logMAR in the CCI and OCCI groups, respectively. The change in corneal astigmatism was 0.52 ± 0.22D and 1.06 ± 0.23D in the CCI and OCCI groups, respectively (P<0.001). Total corneal higher-order aberrations (HOAs) and trefoil increased in both groups (P<0.05); however, there was no difference in the change in total corneal HOAs between the two groups (P>0.05). Conclusions: CCI and OCCI made on a steep axis could be an option for correction of mild-to-moderate astigmatism during cataract surgery with multifocal IOL implantation.

Comparing prediction accuracy between total keratometry and conventional keratometry in cataract surgery with refractive multifocal intraocular lens implantation

We aimed to compare refractive outcomes between total keratometry using a swept-source optical biometer and conventional keratometry in cataract surgery with refractive multifocal intraocular lens (IOL) implantation. We included patients who underwent cataract surgery with refractive multifocal IOL implantation. The IOL power was calculated using conventional formulas (Haigis, SRK/T, Holladay 2, and Barrett Universal II) as well as a new formula (Barrett TK Universal II). The refractive mean error, mean absolute error, and median absolute error were compared, as were the proportions of eyes within ± 0.25 diopters (D), ± 0.50 D, and ± 1.00 D of prediction error. In total 543 eyes of 543 patients, the absolute prediction error of total keratometry was significantly higher than that of conventional keratometry using the SRK/T (P = 0.034) and Barrett Universal II (P = 0.003). The proportion of eyes within ± 0.50 D of the prediction error using the SRK/T and Barrett Universal II was also significantly higher when using conventional keratometry than total keratometry (P = 0.010 for SRK/T and P = 0.005 for Barrett Universal II). Prediction accuracy of conventional keratometry was higher than that of total keratometry in cataract surgery with refractive multifocal IOL implantation.

Effect of Multifocal Intraocular Lens on Contrast Sensitivity in Primary Angle-Closure Patients

Introduction: Cataract surgery with intraocular lens (IOL) implantation in primary angle-closure glaucoma (PACG) has been reported to improve visual acuity, and to reduce postoperative intraocular pressure (IOP) and the number of required medications. Few studies have reported the use of multifocal IOL (MIOL) in PACG. Since both MIOL and glaucoma can decrease contrast sensitivity (CS), this study was to evaluate the effect of MIOL implantation on CS compared to monofocal IOL (mIOL) in primary angle-closure (PAC) or PACG.Methods: This prospective study included patients with PAC or PACG and visually significant cataract. Phacoemulsification with MIOL or mIOL (patient preference) was performed. Collected data included best-corrected distant visual acuity (BCVA), intraocular pressure (IOP), anterior chamber depth (ACD), and contrast sensitivity (CS) measured at spatial frequency 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree (CPD) preoperatively, and at 2-6 months postoperatively. Preoperative and postoperative parameters were then compared. Results: Of the 45 eyes from 35 patients that were enrolled, 33 eyes (15 PAC, 18 PACG) from 26 patients completed the study. Fourteen eyes (11 patients) received diffractive MIOL, and 19 eyes (15 patients) received aspheric mIOL. Preoperative CS was not significantly different between groups. Postoperatively, BCVA, and CS at each spatial frequency were significantly improved in both groups (all p<0.001). Mean postoperative CS at spatial frequency 1.5, 3.0, 6.0, 12.0, and 18.0 CPD was 28.03, 42.63, 44.84, 10.82, and 2.86 in the MIOL group, and 29.55, 49.63, 46.20, 16.83, and 7.09 in the mIOL group, both respectively. Postoperative CS was not significant different between groups at any spatial frequencies. IOP was decreased (p=0.001) and ACD increased (p<0.001) postoperatively in both groups. Conclusion: No significant difference in contrast sensitivity was observed between MIOL and mIOL after cataract removal in PAC/PACG. Multifocal IOL can be considered in primary angle-closure eyes.