Tolerance to residual astigmatism of an isofocal intraocular lens.

PURPOSE: To evaluate the impact of residual astigmatism on the optical and visual performance of an enhanced-monofocal isofocal intraocular lens (EM Isopure, BVI medical, Belgium) compared to a monofocal one (Micropure, BVI medical, Belgium). METHODS: Laboratory investigation and prospective, comparative and randomized clinical study. Optical quality was assessed on an optical bench for 2.0, 3.0, and 4.5 mm pupils. The effect of residual astigmatism was investigated from through-focus images recorded with increasing amounts of regular positive astigmatism induced with a deformable mirror. To evaluate the impact of residual astigmatism, 28 eyes of 28 patients were randomly assigned to either group. Residual astigmatism was induced with positive and negative cylinder lenses at 90 and 180°. Visual acuity (VA) was measured at each step. RESULTS: The optical performance of both IOLs was quite similar for 2.0 and 3.0 mm pupils. For 4.5-mm pupil, the EM Isopure showed a significant reduction of its optical quality in comparison with the monofocal IOL. When visual performance was evaluated, no statistically significant differences were found for any power of induced astigmatism. More differences were found when positive induced astigmatism was compared within each group, and VA was better when the astigmatism was induced at 180° vs. 90°. The greatest differences were found for and induced positive astigmatism of + 1.50D (p = 0.009 for Isopure and p = 0.023 for Micropure). CONCLUSIONS: The tolerance to residual astigmatism of the EM Isopure lens is similar to that of a reference monofocal lens with pupils up to 3.5 mm.

Optical quality in vitro and in vivo of an extended depth-of-focus intraocular lens with isofocal design.

PURPOSE: The aim of this study is to compare optical quality results obtained in laboratory analysis (in vitro) versus clinical data (in vivo). METHODS: The optical quality of ISOPure intraocular lens was assessed both in vitro and in vivo using the modulation transfer function (MTF) for 3.0 and 4.5 mm pupil diameters. In vitro measurements were obtained using deflectometer NIMO TRF1504, while in vivo measurements were taken with OPD-Scan III in a set of patients implanted with this lens. Ray tracing techniques were used to determine the MTF and area under MTF curve (MTFa) from the measured wavefront for the isolated lens and for the whole eye. RESULTS: The MTF of the isolated lens obtained under both in vitro and in vivo conditions showed comparable results for both pupil sizes. However, differences were found when comparing the MTF of the whole eye with the lens implanted versus the MTF measured in vitro for 4.5 mm pupil size. Also, the MTFa defocus curve was compared with the defocus curve measured in vivo. CONCLUSION: The defocus curve from the in vivo study aligns closely with the MTFa of the in vitro model, with a useful defocus range of 0.40D. Thus, it is possible to anticipate the visual results of the implanted isofocal lens by using measurements on an optical bench and conducting optical simulations.

Optical and aberrometric evaluation of a new enhanced monofocal intraocular lens with isofocal optic design.

PURPOSE: To evaluate the optical and aberrometric outcomes of an enhanced monofocal intraocular lens (ISOPure) compared with those of a standard monofocal lens (MicroPure) having the same platform and material. METHODS: A prospective, comparative and randomised clinical study. A total of 28 eyes of 28 patients were randomly assigned to either group. Monocular visual acuity (VA) was measured at distance and intermediate under photopic and mesopic conditions. Aberrometry was analysed for 3.0-, 4.0-, 4.5- and 5.0 mm pupils. The contrast sensitivity defocus curve was measured for 3.0- and 4.5-mm pupils, while the modulation transfer function (MTF) and Strehl ratio (SR) were assessed with a double-pass system. All measurements were performed monocularly 3 months after surgery. RESULTS: No significant differences were found for distance VA. Under photopic conditions, intermediate VA was better with the ISOPure lens, while no significant differences were found between the lenses under mesopic conditions. Internal and total aberrations were higher for the ISOPure lens. No significant differences were found for corneal aberrations. Additionally, both the contrast sensitivity defocus curve and optical quality showed similar behaviour for each lens, with the MTF cut-off frequency exceeding 30 c/deg in both cases. CONCLUSION: The isofocal ISOPure lens enhanced intermediate VA without affecting distance VA under photopic conditions. Moreover, there were no significant differences in visual quality between the ISOPure and MicroPure lenses, despite the former exhibiting higher internal and total aberrations than the monofocal model.

Influence of isofocal intraocular lenses on objective refraction based on autorefraction and aberrometry.

PURPOSE: To evaluate and compare the objective refractions obtained by autorefraction and aberrometry under different lighting conditions with an isofocal intraocular lens (Isopure, BVI medical, Liége, Belgium) compared to a monofocal control lens (Micropure, BVI medical, Liége, Belgium) with the same platform and material. METHODS: Prospective, comparative and randomized study on patients undergoing cataract surgery and bilateral isofocal or monofocal IOL implantation. A total of 44 subjects were randomly assigned to either the isofocal group (n = 22) or the Micropure (n = 22). Manifest refraction (MR) was always performed under the same lighting conditions for all the patients. For objective refraction the autorefractor KR8800 and the aberrometer OPD-Scan III (Nidek Inc., Tokyo, Japan.) were used. For each eye included in the study, six result sets were collected: MR, AR (autorefraction measured with the autorefractor), WF-P and WF-M (Zernike-coefficients-based objective refraction, photopic and mesopic pupil size), OPD-C and OPD-M (autorefraction measured with the aberrometer in photopic and mesopic conditions). RESULTS: The mean sphere for MR was 0.03 ± 0.32D for the Isopure group and 0.24 ± 0.22D for the monofocal group (p = 0.013). For the Isopure group, Friedman analysis showed statistically significant differences for sphere measured with WF-P (p = 0.035), WF-M (p = 0.018) and OPD-M (p = 0.000), and SE measured with OPD-M (p = 0.004). In the Micropure lens group, the Friedman analysis showed differences for all values studied (p < 0.05). Correlation coefficients showed that AR is the objective method with the strongest correlation values for all components of refraction for both groups. CONCLUSION: The modification of the surfaces of the isofocal lens does not have a negative impact on the refraction obtained by AR compared to a standard monofocal intraocular lens.

Visual and optical quality of enhanced intermediate monofocal versus standard monofocal intraocular lens.

PURPOSE: Intraocular lens designs are constantly evolving, trying to obtain more spectacle independence after cataract surgery. This advantage can be linked to some disadvantages, such as optical quality decrease. For that reason, it is important to assess, not only the amount of vision provided but also the quality of vision once they are implanted. The purpose of the present work was to compare the visual performance between two monofocal intraocular models: a standard model and a monofocal with enhanced intermediate vision lens. METHODS: Prospective, randomized, comparative study. Sixty adult subjects scheduled to undergo bilateral cataract surgery and IOL implantation were randomized to receive one of the two IOLs in both eyes at Miranza IOA, Madrid, Spain (group A: monofocal with enhanced intermediate vision lens and group B: standard monofocal lens). Monocular outcomes (right eyes) determined 1 and 3 months postoperatively were photopic corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), perceived halo, corrected intermediate-distance contrast sensitivity, and higher-order aberrations. The impact of the new IOL in the postoperative management with autorefraction devices was also evaluated. RESULTS: No differences were found in CDVA between the two groups. Significant differences were detected between the two lenses evaluated in both total HOA (p = 0.028) and internal HOA (p = 0.037). Contrast sensitivity and halometry results obtained at 1 month were similar across the two IOL groups. CONCLUSION: In patients undergoing cataract surgery, monofocal with enhanced intermediate vision IOL offered similar distance performance and contrast sensitivity along with perceived HOA and halos compared with the standard monofocal IOLs tested.

Optical and Clinical Outcomes of an Isofocal Intraocular Lens vs. a Monofocal Standard Lens.

The aim of this study is to evaluate the results obtained on the optical bench and clinically with an isofocal lens (ISOPure, BVI medical, Belgium) to compare them to a standard monofocal one (MicroPure, BVI medical, Belgium). To do so, we have combined laboratory investigation and a prospective, comparative, and randomized clinical study. First, we have measured the wavefront of the two models studied using a NIMO TR1504 (Lambda-X, Belgium) deflectometer for three nominal powers: +10.00, +20.00 and +30.00 D. In the randomized study with 48 patients, half of them implanted with ISOPure and the other with MicroPure, we have measured visual acuities and contrast sensitivity under photopic and mesopic conditions. The optical bench results show that the isofocal lens presented higher power than the monofocal one, at the lens center, due to the spherical aberration (coefficients Z(4,0), Z(6,0) and Z(8,0)) induced by the greater asphericity of its design. The addition obtained depended on the nominal power, from +1.00 to +1.50 D. The results of the clinical study showed that the ISOPure lens presented better visual outcomes, which were statistically significant, at intermediate distance compared to the MicroPure lens (p-values of 0.014 and 0.022 for 80 and 60 cm, respectively) without decreasing the contrast sensitivity. Clinical outcomes were not affected by pupillary size. In conclusion, due to the increase in power at the lens center due to its highly aspherical design, the isofocal lens evaluated showed better intermediate vision than the monofocal one.