Defocus curves: Focusing on factors influencing assessment

ABSTRACT

Defocus curve assessment is used to emulate defocus over a range of distances and is a valuable tool that is used to differentiate the performance of presbyopia-correcting intraocular lenses. However, defocus curves are limited by a lack of standardization, and multiple factors can impact their generation and interpretation. This review discusses key factors that influence the assessment of defocus curves, including pupil size, level of contrast, sphere versus cylinder defocus, viewing distance, monocular versus binocular assessment, use of Snellen versus logarithm of the minimum angle of resolution charts, and diopter range and step size. There are also different methods to analyze defocus curves, including the direct comparison method, range-of-focus analysis, and area under the curve analysis, which can impact result interpretation. A good understanding of these factors and standardization of the methodology are important to ensure optimal cross-study comparisons.

Comparison of the Clinical Performance of Refractive Rotationally Asymmetric Multifocal IOLs with Other Types of IOLs: A Meta-Analysis

Objective

To compare the clinical performance of refractive rotationally asymmetric multifocal intraocular lens (IOLs) with spherical monofocal, accommodating, and bifocal IOLs.

Methods

A comprehensive literature search of PubMed, EMBASE, Cochrane Controlled Trials Register, and Web of Science up to February 2017 was performed to identify randomized controlled trials (RCT) and comparative cohort studies. Main outcomes were uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), higher-order aberrations (HOAs), MTF, Strehl ratio, and residual sphere and cylinder.

Results

Mplus provided significantly worse UDVA than spherical monofocal IOLs (WMD: 0.13, P=0.008), but significantly better UIVA than high-add bifocal IOLs (WMD: −0.19, P < 0.00001), spherical monofocal IOLs (WMD: −0.12, P < 0.0001), and accommodating IOLs (WMD: −0.21, P < 0.00001). Mplus provided significantly worse UNVA than high-add bifocal IOLs (WMD: 0.07, P < 0.00001), but significantly better UNVA than spherical monofocal IOLs (WMD: −0.19, P < 0.00001). Mplus resulted in significantly higher HOAs than high-add bifocal IOLs (WMD: 0.38, P < 0.00001) and spherical monofocal IOLs (WMD: 0.51, P=0.0004). Mplus provided a significantly lower MTF cut-off and Strehl ratio than other type of IOLs.

Conclusion

The Mplus IOLs perform best regarding intermediate visual acuity whereas they lack in distance visual acuity compared to monofocal IOLs and near visual acuity compared to bifocal IOLs. These results may be due to structure of Mplus IOLs resulting in higher-order aberrations.

Validity of automated refraction after segmented refractive multifocal intraocular lens implantation

AIM

To evaluate the clinical utility of automated refraction (AR) and keratometry (KR) compared with subjective or manifest refraction (MR) after cataract or refractive lens exchange surgery with implantation of Lentis Mplus X (Oculentis GmbH) refractive multifocal intraocular lens (IOL).

METHODS

Eighty-six eyes implanted with the Lentis Mplus X multifocal IOL were included. MR was performed in all patients followed by three consecutive AR measurements using the Topcon KR-8000 autorefractor. Assessment of repeatability of consecutive AR before and after dilation with phenylephrine 10%, and comparison of the AR and KR with MR using vector analysis were performed at 3mo follow-up.

RESULTS

Analysis showed excellent repeatability of the AR measurements. Linear regression of AR versus MR showed good correlation for sphere and spherical equivalent, whereas the correlation for astigmatism was low. The mean difference AR-MR was -1.28±0.29 diopters (D) for sphere. Astigmatism showed better correlation between KR and MR.

CONCLUSION

We suggest AR sphere plus 1.25 D and the KR cylinder as the starting point for MR in eyes with a Lentis Mplus X multifocal IOL. If AR measurements are equal to MR, decentration of the IOL should be suspected.

Comparative analysis of the visual and refractive outcomes of a refractive segmented multifocal intraocular lens with and without toricity: 1-year results

PURPOSE

To compare the visual and refractive outcomes up to 1 year postoperatively following implantation of a refractive segmented or a refractive segmented toric multifocal intraocular lens (IOL).

METHODS

This retrospective study included 108 eyes of 64 patients who underwent cataract surgery with implantation of a refractive segmented multifocal IOL (Lentis Mplus LS-313 MF30 IOL) (LM group) and 81 eyes of 49 patients with implantation of a refractive segmented toric multifocal IOL (Lentis Mplus LU-313 MF30T IOL) (LMT group). The visual and refractive postoperative outcomes and the rate of additional refractive procedures were evaluated up to 1 year postoperatively.

RESULTS

The uncorrected distance visual acuity (VA) and uncorrected near VA exceeded 1.0 and 0.60 in decimal VA, respectively, and both were stable postoperative groups. The postoperative subjective refractive astigmatism was also stable and the postoperative refraction was near emmetropia in both groups. No significant differences were found in the need for additional surgical refractive procedures.

CONCLUSION

The outcomes with a refractive segmented toric multifocal IOL were comparable to those with a non-toric model despite higher preoperative corneal astigmatism.

Testing vision with angular and radial multifocal designs using Adaptive Optics

Multifocal vision corrections are increasingly used solutions for presbyopia. In the current study we have evaluated, optically and psychophysically, the quality provided by multizone radial and angular segmented phase designs. Optical and relative visual quality were evaluated using 8 subjects, testing 6 phase designs. Optical quality was evaluated by means of Visual Strehl-based-metrics (VS). The relative visual quality across designs was obtained through a psychophysical paradigm in which images viewed through 210 pairs of phase patterns were perceptually judged. A custom-developed Adaptive Optics (AO) system, including a Hartmann-Shack sensor and an electromagnetic deformable mirror, to measure and correct the eye's aberrations, and a phase-only reflective Spatial Light Modulator, to simulate the phase designs, was developed for this study. The multizone segmented phase designs had 2-4 zones of progressive power (0 to +3D) in either radial or angular distributions. The response of an "ideal observer" purely responding on optical grounds to the same psychophysical test performed on subjects was calculated from the VS curves, and compared with the relative visual quality results. Optical and psychophysical pattern-comparison tests showed that while 2-zone segmented designs (angular & radial) provided better performance for far and near vision, 3- and 4-zone segmented angular designs performed better for intermediate vision. AO-correction of natural aberrations of the subjects modified the response for the different subjects but general trends remained. The differences in perceived quality across the different multifocal patterns are, in a large extent, explained by optical factors. AO is an excellent tool to simulate multifocal refractions before they are manufactured or delivered to the patient, and to assess the effects of the native optics to their performance.

Visual Performance after Bilateral Implantation of a Four-Haptic Diffractive Toric Multifocal Intraocular Lens in High Myopes

Background. The vision with diffractive toric multifocal intraocular lenses after cataract surgery in long eyes has not been studied previously. Objectives. To report visual performance after bilateral implantation of a diffractive toric multifocal intraocular lens in high myopes. Methods. Prospective, observational case series to include patients with axial length of ≥26 mm and corneal astigmatism of >1 dioptre who underwent bilateral AT LISA 909M implantation. Postoperative examinations included photopic and mesopic distance, intermediate, and near visual acuity; photopic contrast sensitivity; visual symptoms (0–5); satisfaction (1–5); and spectacle independence rate. Results. Twenty-eight eyes (14 patients) were included. Postoperatively, mean photopic monocular uncorrected distance, intermediate, and near visual acuities (logMAR) were 0.12 ± 0.20 (standard deviation), 0.24 ± 0.16, and 0.29 ± 0.21, respectively. Corresponding binocular values were −0.01 ± 0.14, 0.13 ± 0.12, and 0.20 ± 0.19, respectively. One eye (4%) had one-line loss in vision. Under mesopic condition, intermediate vision and near vision decreased significantly (all P ≤ 0.001). Contrast sensitivity at all spatial frequencies did not improve significantly under binocular condition (all P > 0.05). Median scores for halos, night glare, starbursts, and satisfaction were 0.50, 0.00, 0.00, and 4.25, respectively. Ten patients (71%) reported complete spectacle independence. Conclusions. Bilateral implantation of the intraocular lens in high myopes appeared to be safe and achieved good visual performance and high satisfaction.

Range of refractive independence and mechanism of action of a corneal shape-changing hydrogel inlay: results and theory

PURPOSE

To demonstrate the independence of visual performance over a range of preoperative refraction and age in presbyopes implanted with a corneal shape-changing inlay (Raindrop Near Vision Inlay).

SETTING

Two multispecialty clinics, Monterrey and Tijuana, Mexico.

DESIGN

Prospective case series.

METHODS

The nondominant eyes of patients were implanted with the hydrogel corneal inlay beneath a femtosecond flap, centered on the pupil. Clinical outcomes included uncorrected near, intermediate, and distance visual acuity (UNVA, UIVA, and UDVA) and patient-assessed task performance in good light and dim light. Statistical analyses assessed the dependencies on preoperative age (45 to 60 years) and preoperative manifest refraction spherical equivalent (MRSE) (-0.5 to +1.5 diopters [D]). Using the inlay effect derived from wavefront measurements, an eye model was created through which letter charts were simulated.

RESULTS

The study evaluated eyes of 188 patients. Postoperative UNVA, UIVA, and task performance at these distances in good light was independent of age and preoperative MRSE (P > .05). Postoperative UDVA was weakly dependent on preoperative MRSE, but distance task performance in good light was not (P > .05). In the treated eye, the mean postoperative UNVA was 20/25, UIVA was 20/25, and UDVA was 20/32. The clinical outcomes are explained by consideration of zones within the pupil generating good near, intermediate, and distance image quality. This was confirmed by visual acuity simulations.

CONCLUSIONS

The continuous center-near power profile induced by the corneal shape-changing inlay provides good visual acuity and performance from distance through near over a 2.0 D range of preoperative refraction and presbyopic age.

FINANCIAL DISCLOSURE

Drs. Steinert, Schwiegerling, Barragán-Garza, and Chayet are consultants to Revision Optics, Inc. Drs. Lang and Holliday and Mr. Roy are employees of Revision Optics, Inc. Drs. Steinert, Schwiegerling, Barragán-Garza, and Chayet have no financial or proprietary interest in any material or method mentioned.

Treatment of Presbyopia in Emmetropes Using a Shape-Changing Corneal Inlay: One-Year Clinical Outcomes

PURPOSE

To report 1-year safety and efficacy clinical outcomes of a shape-changing corneal inlay for the treatment of presbyopia.

DESIGN

Prospective, nonrandomized, multicenter United States Food and Drug Administration Investigational Device Exemption clinical trial (clinicaltrials.gov identifier, NCT01373580).

PARTICIPANTS

Nondominant eyes (N = 373) of emmetropic presbyopic subjects were implanted at 11 sites with the Raindrop Near Vision Inlay (ReVision Optics, Lake Forest, CA); 340 eyes underwent the 1-year follow-up visit.

METHODS

The corneal inlay was implanted under a corneal flap at the center of the light-constricted pupil created with a femtosecond laser.

MAIN OUTCOME MEASURES

For subjects completing the 1-year follow-up, monocular and binocular uncorrected and corrected visual acuity, refractive stability, contrast sensitivity (CS; photopic and mesopic), symptom and satisfaction questionnaire results, and adverse events.

RESULTS

At 1 year in the treated eye, on average, uncorrected near visual acuity (UNVA) improved by 5.1 lines, uncorrected intermediate visual acuity (UIVA) improved by 2.5 lines, and uncorrected distance visual acuity (UDVA) decreased by 1.2 lines. From 3 months through 1 year, 93% of subjects achieved UNVA of 20/25 or better, 97% achieve UIVA of 20/32 or better, and 95% achieved UDVA of 20/40 or better. Binocularly, the mean UDVA exceeded 20/20 from 3 months through 1 year. Contrast sensitivity loss occurred only at the highest spatial frequencies, with no loss binocularly. Absent or mild scores were reported in 96% of subjects for visual symptoms (glare, halos, double vision, and fluctuations in vision), in 99% for ocular symptoms (pain, light sensitivity, and discomfort), and in 95% for dryness. Adverse events were treatable and resolved. Eighteen inlays were replaced, usually soon after implantation because of decentration, but UNVA was little affected in this group thereafter. In the 11 cases requiring inlay explantations, 100% achieved a corrected distance visual acuity of 20/25 or better by 3 months after explant.

CONCLUSIONS

The Raindrop Near Vision Inlay provides significant improvement in near and intermediate visual performance, with no significant change in binocular distance vision or CS. Subject satisfaction is improved significantly with minimal ocular or visual symptoms.

Intraocular Lens Fragmentation Using Femtosecond Laser: An In Vitro Study

PURPOSE

To transect intraocular lenses (IOLs) using a femtosecond laser in cadaveric human eyes. To determine the optimal in vitro settings, to detect and characterize gasses or particles generated during this process.

METHODS

A femtosecond laser was used to transect hydrophobic and hydrophilic acrylic lenses. The settings required to enable easy separation of the lens fragment were determined. The gasses and particles generated were analysed using gas chromatography mass spectrometer (GC-MS) and total organic carbon analyzer (TOC), respectively.

RESULTS

In vitro the IOL fragments easily separated at the lowest commercially available energy setting of 1 μJ, 8-μm spot, and 2-μm line separation. No particles were detected in the 0.5- to 900-μm range. No significant gasses or other organic breakdown by products were detected at this setting. At much higher energy levels 12 μJ (4 × 6 μm spot and line separation) significant pyrolytic products were detected, which could be harmful to the eye. In cadaveric explanted IOL capsule complex the laser pulses could be applied through the capsule to the IOL and successfully fragment the IOL.

CONCLUSION

IOL transection is feasible with femtosecond lasers. Further in vivo animal studies are required to confirm safety.

TRANSLATIONAL RELEVANCE

In clinical practice there are a number of large intraocular lenses that can be difficult to explant. This in-vitro study examines the possibility of transecting the lasers quickly using femtosecond lasers. If in-vivo studies are successful, then this innovation could help ophthalmic surgeons in IOL explantation.

Reduction in mean deviation values in automated perimetry in eyes with multifocal compared to monofocal intraocular lens implants

PURPOSE

To evaluate differences in mean deviation values in automated perimetry in healthy eyes with multifocal compared to monofocal intraocular lens (IOL) implants.

DESIGN

Prospective, age-matched, comparative analysis.

METHODS

SETTING

Single-center, tertiary referral academic practice.

PATIENT POPULATION

A total of 37 healthy eyes in 37 patients with bilateral multifocal (n=22) or monofocal (n=15) IOL implants were studied. INTERVENTION/OBSERVATION PROCEDURE: Humphrey Visual Field 10-2 testing was performed on all patients.

MAIN OUTCOME MEASURES

Mean deviation (MD) and pattern standard deviation (PSD) numerical values were evaluated and compared between groups.

RESULTS

The average MD was -2.84 dB (SD 2.32) for the multifocal IOL group and -0.97 dB (SD 1.58) for the monofocal IOL group (P=.006). There was no significant difference in PSD between the 2 groups (P=.99). Eyes that had the visual field 10-2 testing≥6 months from time of IOL placement showed no improvement in MD when compared to eyes that were tested within 6 months from IOL placement.

CONCLUSION

Multifocal IOL implants cause significant nonspecific reduction in MD values on Humphrey Visual Field 10-2 testing that does not improve with time or neuroadaptation. Multifocal IOL implants may be inadvisable in patients where central visual field reduction may not be tolerated, such as macular degeneration, retinal pigment epithelium changes, and glaucoma.

Visual outcomes and patient satisfaction in 9366 eyes using a refractive segmented multifocal intraocular lens

PURPOSE

To report the effectiveness, patient satisfaction, and complication rate with a zonal refractive intraocular lens (IOL) in a high volume of patients.

SETTING

Private clinic, London, United Kingdom.

DESIGN

Case series.

METHODS

Retrospective data of patients with binocular Lentis Mplus IOLs were analyzed. The main outcome measures were uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), corrected distance visual acuity, manifest refraction, patient satisfaction, and complications. One-month, 3-month, and 6-month data were analyzed.

RESULTS

The study comprised 9366 eyes of 4683 patients. The mean spherical equivalent changed from +1.73 diopters (D) ± 3.37 (SD) preoperatively to -0.02 ± 0.60 D at 3 months and +0.03 ± 0.60 D at 6 months. Ninety-five percent of patients achieved a binocular UDVA of 6/7.5 (0.1 logMAR) or better 3 months postoperatively. The mean binocular UNVA was 0.155 ± 0.144 logMAR and 0.159 ± 0.143 logMAR at 3 months and 6 months, respectively. Severe dysphotopsia requiring an IOL exchange occurred in 55 eyes. Patient satisfaction was high, with 97.5% of patients willing to recommend the procedure.

CONCLUSIONS

The zonal refractive IOL provided excellent distance and near visual acuity. The postoperative complication rate was clinically acceptable, and patient satisfaction high.

FINANCIAL DISCLOSURE

Dr. Schallhorn is a consultant to Abbott Medical Optics, Inc. No author has a financial or proprietary interest in any material or method mentioned.

[Clinical results after implantation of a new segmental refractive multifocal intraocular lens]

BACKGROUND

The aim of the study was a clinical evaluation of an intraocular lens (IOL) with a segmental multifocal optic design and near addition of + 3.0 D as part of a CE approval study.

PATIENTS AND METHODS

In a multicenter study the LENTIS Mplus LS-312 MF IOL (Oculentis) was implanted in 134 eyes of 79 patients with a mean age of 68 ± 12 years. The multifocality is achieved by implementation of a distance part and a segmented near sector. Three months after surgery, uncorrected and best corrected distance visual acuity (UCDVA and BCDVA, respectively), near visual acuity (UCNVA and BCNVA, respectively), contrast vision and patient satisfaction (questionnaire) were evaluated.

RESULTS

The IOLs were implanted uneventfully either unilaterally or bilaterally and 3 months postoperatively (n = 86 eyes) the following mean visual acuities were obtained (logMAR): UCDVA = 0.05, BCDVA = - 0.01, UCNVA = 0.09 and BCNVA = 0.02. Contrast sensitivity (n = 25 eyes) was within normal limits. Of the 66 questioned patients 10.6% spontaneously reported halos and 3% glare.

CONCLUSION

This new innovative multifocal IOL concept showed very good functional results as well as high patient satisfaction.