Subjective and objective refractions in eyes with extended-depth-of-focus intraocular lenses using echelette optics: clinical and experimental study

Clinical outcomes in eyes with diffractive continuous depth-of-focus intraocular lenses enhanced for near vision: comparison with trifocal intraocular lenses

BACKGROUND

To prospectively evaluate visual functions and patient satisfaction after bilateral implantation of diffractive continuous depth-of-focus intraocular lens (CDF IOL) compared with trifocal IOLs.

METHODS

This investigator-initiated study was approved by a certified local review board (registered: jRCTs032210305). CDF IOL (Synergy, J&J, group S) and trifocal IOL (AcrySof PanOptix, Alcon, group P) were implanted bilaterally in 30 patients each. Three months postoperatively, binocular outcomes of uncorrected (BUCVA) and distance-corrected (BDCVA) visual acuities at distances of 0.3, 0.4, 0.5, 0.7, and 5 m were measured. Contrast sensitivities were binocularly measured using CSV-1000 (2.5 m) and Pelli-Robson charts at distances of 0.4 and 1 m. Symptoms of glare, halo, starburst, and waxy vision, and satisfaction for near, intermediate, and far visions were assessed with questionnaires. Differences between the two groups were examined.

RESULTS

Twenty-seven patients each completed the follow-up. The mean age of the group S was lower than that of the group P (P < 0.001). The BUCVA at 0.4 m was better in the S group, while the mean manifest refraction of the P group showed a significant hyperopic shift (P < 0.001). BDCVA was significantly better in the S group. The contrast sensitivity results at three distances showed no discernible differences. Although more patients in the S group reported significant glare and halo, their satisfaction with near vision was higher.

CONCLUSIONS

The binocular visual function of patients with CDF IOLs was comparable to or better than that of patients with trifocal IOLs. The patients were satisfied with near vision, despite the enhanced glare and halo. Understanding the differences between the two types of presbyopia-correcting IOLs is important to ensure patient satisfaction.

TRIAL REGISTRATION

This clinical trial was registered in the Japan Registry for Clinical Research (identifier: jRCTs032210305) on September 13, 2021.

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 function in eyes with diffractive extended depth-of-focus and monofocal intraocular lenses: 2-year comparison

PURPOSE

To compare long-term visual function after implantation of diffractive extended depth-of-focus (EDF) intraocular lenses (IOLs) using echelett optics and monofocal IOLs with the same platform.

METHODS

In this prospective comparative case series, diffractive EDF or monofocal IOLs were implanted binocularly and followed up for 2 years. At the last visit, distance-corrected binocular visual acuities were measured at distances of 0.3, 0.5, 0.7, 1, 2, 3, and 5 m. Photopic and mesopic contrast sensitivity was also examined. Dynamic visual function was evaluated in terms of functional visual acuity (FVA), standard deviation of visual acuity (SDVA), visual maintenance ratio (VMR), mean response time, and number of blinks. The outcomes were compared between the two IOLs, and the influence of posterior capsule opacification (PCO) on contrast sensitivity and FVA was examined.

RESULTS

Binocular visual acuity of eyes with EDF IOLs was better at distances of 0.5 and 0.7 m than that of eyes with monofocal IOL (P < 0.026). There were no differences in binocular visual acuity at other distances, contrast sensitivities, or dynamic visual functions. The influence of PCO on the visual functions was not found in eyes with EDF IOLs.

CONCLUSION

Up to 2 years postoperatively, eyes with diffractive EDF IOLs sustained superior intermediate visual acuity together with visual function comparable to that of eyes with monofocal IOLs.

Comparative analysis of visual outcomes with 2 enhanced monofocal intraocular lenses

PURPOSE

To compare the visual performance, spectacle independence, and subjective visual quality of 2 enhanced monofocal intraocular lenses (IOLs): Eyhance ICB00 and ZOE Primus-HD.

SETTING

Ophthalmology Department, San Raffaele Scientific Institute, Milan, Italy.

DESIGN

Prospective case series.

METHODS

Patients without ocular comorbidities and corneal astigmatism <0.75 diopters (D) undergoing cataract surgery with bilateral implantation of enhanced monofocal Eyhance and ZOE were included. 6 months postoperatively, the following parameters were analyzed: subjective and objective refraction; monocular and binocular corrected (4 m) and uncorrected (UDVA) distance visual acuities; corrected distance, intermediate (66 cm), and near (40 cm) visual acuities, as well as uncorrected intermediate (UIVA) and uncorrected near (UNVA) visual acuities; photopic contrast sensitivity; binocular defocus curve; halo and glare perception; and spectacle independence.

RESULTS

100 eyes of 50 patients were evaluated (25 patients per IOL group). The 2 IOLs showed superimposable visual performances, without significant differences in terms of refractive and visual outcomes, defocus curves, contrast sensitivity, scores of vision quality, and spectacle independence. Of note, monocular and binocular UDVA was excellent in both groups. The 2 IOL models achieved satisfactory binocular UIVA, with more than 70% of patients reaching a binocular UIVA of ≤0.1 logMAR. Up to 84% of patients eventually declared to feel comfortable frequently while staying at intermediate distance.

CONCLUSIONS

The general visual outcome of the Eyhance ICB00 and the ZOE Primus-HD enhanced monofocal IOLs is similar, with special reference to the satisfactory spectacle independence for intermediate distance.

Refraction and defocus curves in eyes with monofocal and multifocal intraocular lenses

Several clinical techniques have been described to evaluate visual performance and optical quality with intraocular lenses (IOL). However, subjective refraction remains one of the most important methods for assessing post-surgery results, taking decisions about retreatments, advanced spectacle prescription and the refinement of the constant for the formula used in the IOL power calculation. Beyond clinical refraction, defocus curve measurement has been described as a complementary tool for assessing visual performance and taking clinical decisions. However, to date, there are no clinical guidelines or evidence-based protocols published in the scientific literature recommended for pseudophakic patients implanted with either monofocal or multifocal IOLs. This narrative review highlights the importance of clinical refraction in pseudophakic eyes, its utility in the decision of different types of IOL implantation, and describes a clinical refraction protocol for eyes implanted with monofocal and multifocal IOLs.

Automated and subjective refraction with monofocal, multifocal, and EDOF intraocular lenses: review

Automated refraction (Scheiner principle) is universally used to start a visual examination. Although the results are reliable in eyes implanted with monofocal intraocular lenses (IOLs), they may be less precise with multifocal (mIOL) or extended depth-of-focus (EDOF) IOLs and can even indicate a refractive error that does not clinically exist. Autorefractor results with monofocal, multifocal, and EDOF IOLs were investigated through literature search analyzing the papers reporting the difference between automated and clinical refraction. The average difference ranged between -0.50 diopter (D) and -1.00 D with most mIOL and EDOF IOLs. The differences in astigmatism were generally much lower. Autorefractors using infrared light cannot measure eyes with high technology IOLs precisely because of the influence of the refractive or of the diffractive near add. The systematic error induced with some IOLs should be mentioned in the IOL label to prevent possible inappropriate refractive procedures to treat apparent myopia.

Patient reported outcomes after implementation of an enhanced depth of focus intraocular lens with low postoperative myopia

Background

Enhanced depth-of- focus intraocular lenses (EDOF IOL) have filled the gap between monofocal and multifocal intraocular implants with optical qualities of monofocal lenses and usually minor dysphotopsias typical for multifocal lenses. The purpose of this study was to evaluate visual outcomes after bilateral implantation of a new EDOF IOL in patients with requirements for perfect near and intermediate vision.

Methods

The study included 15 patients (29 eyes as one was amblyopic) with bilateral implantation of LUXSMART EDOF IOL (Bausch & Lomb) with a targeted myopia (between -0.25 and -0.50D) in both eyes. Monocular corrected and uncorrected visual acuity for far, intermediate and near as well as refractive outcomes were evaluated at 1, 3, 6 and 12 months after the surgery. Additionally, binocular visual acuity, contrast sensitivity and defocus curve were measured at the final follow-up visit. At 12 months' visit patients completed a questionnaire evaluating patient satisfaction, spectacle independence and presence of dysphotopsias.

Results

Binocular uncorrected visual acuities at 12 month's visit were 0.13 ​± ​0.16, 0.06 ​± ​0.08, 0.07 ​± ​0.09 and 0.15 ​± ​0.09 logMAR for far distance, 80 ​cm, 66 ​cm and 40 ​cm respectively. Corrected binocular visual acuities at 12 months were 0.00 ​± ​0.00, 0.05 ​± ​0.07, 0.05 ​± ​0.06, 0.13 ​± ​0.16 respectively for distance, 80 ​cm, 66 ​cm and 40 ​cm. Automated refraction spherical equivalent at 12 months' visit stood at -0.70 ​± ​0.48D, which was 0.46D less than calculated biometric target, however spherical equivalent of subjective refraction at 12 months equaled -0.49 ​± ​0.46D, which was closer to preoperative biometric target. Defocus curve had gentle shape without peaks typical for monofocal IOLs. Binocular contrast sensitivity results were superior to average results for that age group and equaled 1.78 ​± ​0.16 logMAR without correction and 1.81 ​± ​0.13 logMAR with correction. Spectacle independence for near and intermediate distances was achieved in all patients and for far distance in 73.3% of patients. Burdensome dysphotopsias were not reported in any case.

Conclusions

EDOF IOLs targeted bilaterally at low myopia can provide excellent near and intermediate visual acuity and independence of any optical correction in majority of cases. This approach can be used in selected patients who are focused on stationary activities.

Pitfalls of Using NIR-Based Clinical Instruments to Test Eyes Implanted with Diffractive Intraocular Lenses

The strong wavelength dependency of diffractive elements casts reasonable doubts on the reliability of near-infrared- (NIR)-based clinical instruments, such as aberrometers and double-pass systems, for assessing, post-surgery, the visual quality of eyes implanted with diffractive multifocal intraocular lenses (DMIOLs). The results obtained for such patients when using NIR light can be misleading. Ordinary compensation for the refractive error bound to chromatic aberration is not enough because it only considers the best focus shift but does not take into account the distribution of light energy among the foci which strongly depends on the wavelength-dependent energy efficiency of the diffractive orders used in the DMIOL design. In this paper, we consider three commercial DMIOL designs with the far focus falling within the range of (−1, 0, +1)-diffractive orders. We prove theoretically the differences existing in the physical performance of the studied lenses when using either the design wavelength in the visible spectrum or a NIR wavelength (780 to 850 nm). Based on numerical simulation and on-bench experimental results, we show that such differences cannot be neglected and may affect all the foci of a DMIOL, including the far focus.

Visual outcomes of non-diffractive extended-depth-of-focus and enhanced monofocal intraocular lenses: A case-control study

OBJECTIVE

To compare the visual outcomes of a non-diffractive extended-depth-of-focus (EDoF) intraocular lens (IOL) with an enhanced monofocal IOL.

METHODS

We evaluated 76 eyes from 38 patients who had undergone bilateral cataract surgery with implantation of either an EDoF IOL (AcrySof IQ Vivity, n = 40 eyes) or an enhanced monofocal IOL (Tecnis Eyhance, n = 36 eyes). Objective refraction, monocular and binocular uncorrected and corrected distance visual acuity (UDVA, CDVA), uncorrected and distance-corrected intermediate visual acuity (UIVA, DCIVA), uncorrected and distance-corrected near visual acuity (UNVA, DCNVA), binocular defocus curves, contrast sensitivity, halo and glare perception, and spectacle independence were compared.

RESULTS

Monocular and binocular UDVA, CDVA, UIVA, and DCIVA were comparable in both groups, whereas UNVA and DCNVA were significantly better with the Vivity group than with the Eyhance group. The two groups had no statistically significant difference regarding photopic and scotopic contrast sensitivities or halo and glare perception. Compared to the Eyhance IOL, the Vivity IOL had a larger landing zone in the defocus curve and provided higher spectacle independence for near vision.

CONCLUSION

Both the AcrySof IQ Vivity and Tecnis Eyhance IOLs had excellent distant and intermediate visual acuity, while the former had more satisfactory near vision outcomes with greater spectacle independence rate. No differences were obtained between two IOLs in terms of patient satisfaction and visual disturbances such as halo and glare.

Update on Biometry and Lens Calculation - A Review of the Basic Principles and New Developments

These days, accurate calculation of artificial lenses is an important aspect of patient management. In addition to the classic theoretical optical formulae there are a number of new approaches, most of which are available as online calculators. This review aims to explain the background of artificial lens calculation and provide an update on study results based on the latest calculation approaches. Today, optical biometry provides the computational basis for theoretical optical formulae, ray tracing, and also empirical approaches using artificial intelligence. Manufacturer information on IOL design and IOL power recorded as part of quality control could improve calculations, especially for higher IOL powers. With modern measurement data, there is further potential for improvement in the determination of the axial length to the retinal pigment epithelium and by adopting a sum-of-segment approach. With the available data, the cornea can be assumed to be a thick lens. The Kane formula, the EVO 2.0 formula, the Castrop formula, the PEARL-DGS, formula and the OKULIX calculation software provide consistently good results for artificial lens calculations. Excellent refractive results can be achieved using these tools, with approximately 80% having an absolute prediction error within 0.50 dpt, at least in highly selected study populations. The Barrett Universal II formula also produces excellent results in the normal and long axial length range. For eyes with short axial lengths, the use of Barrett Universal II should be reconsidered; in this case, one of the methods mentioned above is preferable. Second Eye Refinement can also be considered in this patient population, in conjunction with established classic third generation formulae.