Effect of position of near addition in an asymmetric refractive multifocal intraocular lens on quality of vision

Purpose
To evaluate the impact of the position of an asymmetric multifocal near segment on visual quality.

Setting
Cathedral Eye Clinic, Belfast, United Kingdom.

Design
Retrospective comparative case series.

Methods
Data from consecutive patients who had bilateral implantation of the Lentis Mplus LS-312 multifocal intraocular lens were divided into 2 groups. One group received inferonasal near-segment placement and the other, superotemporal near-segment placement. A +3.00 diopter (D) reading addition (add) was used in all eyes. The main outcome measures included uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), contrast sensitivity, and quality of vision. Follow-up was 3 months.

Results
Patients ranged in age from 43 to 76 years. The inferonasal group comprised 80 eyes (40 patients) and the superotemporal group, 76 eyes (38 patients). The mean 3-month spherical equivalent was −0.11 D ± 0.49 (SD) in the inferonasal group and −0.18 ± 0.46 D in the superotemporal group. The mean postoperative UDVA was 0.14 ± 0.10 logMAR and 0.18 ± 0.15 logMAR, respectively. The mean monocular UNVA was 0.21 ± 0.14 logRAD and 0.24 ± 0.13 logRAD, respectively. No significant differences were observed in the higher-order aberrations, total Strehl ratio (point-spread function), or modulation transfer function between the groups. Dysphotopic symptoms measured with a validated quality-of-vision questionnaire were not significantly different between groups.

Conclusion
Positioning of the near add did not significantly affect objective or subjective visual function parameters.

The Impact of Multifocal Intraocular Lens in Retinal Imaging with Optical Coherence Tomography

Multifocal intraocular lenses (MF IOLs) have concentric optical zones with different dioptric power, enabling patients to have good visual acuity at multiple focal points. However, several optical limitations have been attributed to this particular design. The purpose of this study is to access the effect of MF IOLs design on the accuracy of retinal optical coherence tomography (OCT). Cross-sectional study conducted at the Refractive Surgery Department of Central Lisbon Hospital Center. Twenty-three eyes of 15 patients with a diffractive MF IOL and 27 eyes of 15 patients with an aspheric monofocal IOL were included in this study. All patients underwent OCT macular scans using Heidelberg Spectralis®. Macular thickness and volume values and image quality (Q factor) were compared between the two groups. There were no statistically significant differences between both groups regarding macular thickness or volume measurements. Retinal OCT image quality was significantly lower in the MF IOL group (p < 0.01). MF IOLs are associated with a significant decrease in OCT image quality. However, this fact does not seem to compromise the accuracy of spectral domain OCT retinal measurements.

Modulation transfer function and optical quality after bilateral implantation of a+3.00 D versus a+4.00 D multifocal intraocular lens

PURPOSE: To determine whether the improvement in intermediate vision after bilateral implantation of an aspheric multifocal intraocular lens (IOL) with a +3.00 diopter (D) addition (add) occurs at the expense of optical quality compared with the previous model with a +4.00 D add. SETTING: Department of Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil. DESIGN: Prospective randomized double-masked comparative clinical trial. METHODS: One year after bilateral implantation of Acrysof Restor SN6AD1 +3.00 D IOLs or Acrysof Restor SN6AD3 +4.00 D IOLs, optical quality was evaluated by analyzing the in vivo modulation transfer function (MTF) and point-spread function (expressed as Strehl ratio). The Strehl ratio and MTF curve with a 4.0 pupil and a 6.0 mm pupil were measured by dynamic retinoscopy aberrometry. The uncorrected and corrected distance visual acuities at 4 m, uncorrected and distance-corrected near visual acuities at 40 cm, and uncorrected and distance-corrected intermediate visual acuities at 50 cm, 60 cm, and 70 cm were measured. RESULTS: Both IOL groups comprised 40 eyes of 20 patients. One year postoperatively, there were no statistically significant between-group differences in the MTF or Strehl ratio with either pupil size. There were no statistically significant between-group differences in distance or near visual acuity. Intermediate visual acuity was significantly better in the +3.00 D IOL group. CONCLUSION: Results indicate that the improvement in intermediate vision in eyes with the aspheric multifocal +3.00 D add IOL occurred without decreasing optical quality over that with the previous version IOL with a +4.00 D add.

Error induced by the estimation of the corneal power and the effective lens position with a rotationally asymmetric refractive multifocal intraocular lens

AIM: To evaluate the prediction error in intraocular lens (IOL) power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position (ELP). METHODS: Retrospective study including a total of 25 eyes of 13 patients (age, 50 to 83y) with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL (Oculentis GmbH, Germany). In all cases, an adjusted IOL power (PIOLadj) was calculated based on Gaussian optics using a variable keratometric index value (nkadj) for the estimation of the corneal power (Pkadj) and on a new value for ELP (ELPadj) obtained by multiple regression analysis. This PIOLadj was compared with the IOL power implanted (PIOLReal) and the value proposed by three conventional formulas (Haigis, Hoffer Q and Holladay). RESULTS: PIOLReal was not significantly different than PIOLadj and Holladay IOL power (P>0.05). In the Bland and Altman analysis, PIOLadj showed lower mean difference (-0.07 D) and limits of agreement (of 1.47 and -1.61 D) when compared to PIOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELPadj was significantly lower than ELP calculated with other conventional formulas (P<0.01) and was found to be dependent on axial length, anterior chamber depth and Pkadj. CONCLUSION: Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing the keratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.

Multifocal intraocular lens differentiation using defocus curves

Purpose: To determine the most appropriate analysis technique for the differentiation of multifocal intraocular lens (MIOL) designs using defocus curve assessment of visual capability.Methods:Four groups of fifteen subjects were implanted bilaterally with either monofocal intraocular lenses, refractive MIOLs, diffractive MIOLs, or a combination of refractive and diffractive MIOLs. Defocus curves between -5.0D and +1.5D were evaluated using an absolute and relative depth-of-focus method, the direct comparison method and a new 'Area-of-focus' metric. The results were correlated with a subjective perception of near and intermediate vision. Results:Neither depth-of-focus method of analysis were sensitive enough to differentiate between MIOL groups (p>0.05). The direct comparison method indicated that the refractive MIOL group performed better at +1.00, -1.00 and -1.50 D and worse at -3.00, -3.50, -4.00 and -5.00D compared to the diffractive MIOL group (p

Can aberrometry provide rapid and reliable measures of subjective depth of focus following multifocal intraocular lens implantation?

Purpose: To determine whether the ‘through-focus’ aberrations of a multifocal and accommodative intraocular lens (IOL) implanted patient can be used to provide rapid and reliable measures of their subjective range of clear vision. Methods: Eyes that had been implanted with a concentric (n = 8), segmented (n = 10) or accommodating (n = 6) intraocular lenses (mean age 62.9 ± 8.9 years; range 46-79 years) for over a year underwent simultaneous monocular subjective (electronic logMAR test chart at 4m with letters randomised between presentations) and objective (Aston open-field aberrometer) defocus curve testing for levels of defocus between +1.50 to -5.00DS in -0.50DS steps, in a randomised order. Pupil size and ocular aberration (a combination of the patient’s and the defocus inducing lens aberrations) at each level of blur was measured by the aberrometer. Visual acuity was measured subjectively at each level of defocus to determine the traditional defocus curve. Objective acuity was predicted using image quality metrics. Results: The range of clear focus differed between the three IOL types (F=15.506, P=0.001) as well as between subjective and objective defocus curves (F=6.685, p=0.049). There was no statistically significant difference between subjective and objective defocus curves in the segmented or concentric ring MIOL group (P>0.05). However a difference was found between the two measures and the accommodating IOL group (P<0.001). Mean Delta logMAR (predicted minus measured logMAR) across all target vergences was -0.06 ± 0.19 logMAR. Predicted logMAR defocus curves for the multifocal IOLs did not show a near vision addition peak, unlike the subjective measurement of visual acuity. However, there was a strong positive correlation between measured and predicted logMAR for all three IOLs (Pearson’s correlation: P<0.001). Conclusions: Current subjective procedures are lengthy and do not enable important additional measures such as defocus curves under differently luminance or contrast levels to be assessed, which may limit our understanding of MIOL performance in real-world conditions. In general objective aberrometry measures correlated well with the subjective assessment indicating the relative robustness of this technique in evaluating post-operative success with segmented and concentric ring MIOL.

Analysis of internal astigmatism and higher order aberrations in eyes implanted with a new diffractive multifocal toric intraocular lens

Background To evaluate the intraocular lens (IOL) position by analyzing the postoperative axis of internal astigmatism as well as the higher-order aberration (HOA) profile after cataract surgery following the implantation of a diffractive multifocal toric IOL. Methods Prospective study including 51 eyes with corneal astigmatism of 1.25D or higher of 29 patients with ages ranging between 20 and 61 years old. All cases underwent uneventful cataract surgery with implantation of the AT LISA 909 M toric IOL (Zeiss). Visual, refractive and corneal topograpy changes were evaluated during a 12-month follow-up. In addition, the axis of internal astigmatism as well as ocular, corneal, and internal HOA (5-mm pupil) were evaluated postoperatively by means of an integrated aberrometer (OPD Scan II, Nidek). Results A significant improvement in uncorrected distance and near visual acuities (p < 0.01) was found, which was consistent with a significant correction of manifest astigmatism (p < 0.01). No significant changes were observed in corneal astigmatism (p = 0.32). With regard to IOL alignment, the difference between the axes of postoperative internal and preoperative corneal astigmatisms was close to perpendicularity (12 months, 87.16° ± 7.14), without significant changes during the first 6 months (p ≥ 0.46). Small but significant changes were detected afterwards (p = 0.01). Additionally, this angular difference correlated with the postoperative magnitude of manifest cylinder (r = 0.31, p = 0.03). Minimal contribution of intraocular optics to the global magnitude of HOA was observed. Conclusions The diffractive multifocal toric IOL evaluated is able to provide a predictable astigmatic correction with apparent excellent levels of optical quality during the first year after implantation.

Disk halo size measured in individuals with monofocal versus diffractive multifocal intraocular lenses

PURPOSE: To compare disk halo size in response to a glare source in eyes with an aspheric apodized diffractive multifocal intraocular lens (IOL) or aspheric monofocal IOL. SETTING: Rementeria Ophthalmological Clinic, Madrid, Spain. DESIGN: Prospective randomized masked study. METHOD: Halo radius was measured using a vision monitor (MonCv3) with low-luminance optotypes in eyes that had cataract surgery and bilateral implantion of an Acrysof Restor SN6AD1 multifocal IOL or Acrysof IQ monofocal IOL 6 to 9 months previously. The visual angle subtended by the disk halo radius was calculated in minutes of arc (arcmin). Patient complaints of halo disturbances were recorded. Monocular uncorrected distance visual acutity (UDVA) and corrected distance visual acuity (CDVA) were measured using high-contrast (96%) and low-contrast (10%) logMAR letter charts. RESULTS: The study comprised 39 eyes of 39 subjects (aged 70 to 80 years); 21 eyes had a multifocal IOL and 18 eyes a monofocal IOL. The mean halo radius was 35 arcmin larger in the multifocal IOL group than the monofocal group (P<.05). Greater halo effects were reported in the multifocal IOL group (P<.05). The mean monocular high-contrast UDVA and low-contrast UDVA did not vary significantly between groups, whereas the mean monocular high-contrast CDVA and low-contrast CDVA were significantly worse at 0.12 logMAR and 0.13 logMAR in the multifocal than in the monofocal IOL group, respectively (P <.01). A significant positive correlation was detected by multiple linear regression between the halo radius and low-contrast UDVA in the multifocal IOL group (r = 0.72, P<.001). CONCLUSIONS: The diffractive multifocal IOL gave rise to a larger disk halo size, which was correlated with a worse low-contrast UDVA.

Clinical evaluation of a multifocal aspheric diffractive intraocular lens

Aim: To evaluate the performance of an aspheric diffractive multifocal acrylic intraocular lens (IOL), ZMB00 1-Piece Tecnis. Setting: Five sites across Europe. Methods: Fifty-two patients with cataracts (average age 68.5±10.5 years, 35 female) were bilaterally implanted with the aspheric diffractive multifocal IOL after completing a questionnaire regarding their optical visual symptoms, use of visual correction and their visual satisfaction. The questionnaire was completed again 4-6 months after surgery along with measures of uncorrected and best-corrected distance and near visual acuity, under photopic and mesopic lighting, reading ability, defocus curve testing and ocular examination for adverse events. Results: The residual refractive error was 0.01±0.47D with 56% of eyes within ±0.25D and 97% within ±1.0D. Uncorrected visual acuity was 0.02±0.10logMAR at distance and 0.15±0.30 logMAR at near, only reducing to 0.07±0.10logMAR at distance and 0.21±0.25logMAR at near in mesopic conditions.The defocus curve showed a near addition between 2.5-3.0 D allowing a reading acuity of 0.08±0.13 logMAR, with a range of clear vision <0.3 logMAR of ∼4.0 D. The average reading speed was 121.4±30.8 words per minute. Spectacle independence was 100% for distance and 88% for near, with high levels of satisfaction reported. Overall rating of vision without glasses could be explained (r=0.760) by preoperative best-corrected distance acuity, postoperative reading acuity and postoperative uncorrected distance acuity in photopic conditions (p<0.001). Only two minor adverse events occurred. Conclusions: The ZMB00 1-Piece Tecnis multifocal IOL provides a good visual outcome at distance and near with minimal adverse effects.

Visual outcomes and subjective experience after bilateral implantation of a new diffractive trifocal intraocular lens

Purpose - To assess clinical outcomes and subjective experience after bilateral implantation of a diffractive trifocal intraocular lens (IOL). Setting - Midland Eye Institute, Solihull, United Kingdom. Design - Cohort study. Methods - Patients had bilateral implantation of Finevision trifocal IOLs. Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), and manifest refraction were measured 2 months postoperatively. Defocus curves were assessed under photopic and mesopic conditions over a range of +1.50 to -4.00 diopters (D) in 0.50 D steps. Contrast sensitivity function was assessed under photopic conditions. Halometry was used to measure the angular size of monocular and binocular photopic scotomas arising from a glare source. Patient satisfaction with uncorrected near vision was assessed using the Near Activity Visual Questionnaire (NAVQ). Results - The mean monocular CDVA was 0.08 logMAR ± 0.08 (SD) and the mean binocular CDVA, 0.06 ± 0.08 logMAR. Defocus curve testing showed an extended range of clear vision from +1.00 to -2.50 D defocus, with a significant difference in acuity between photopic conditions and mesopic conditions at -1.50 D defocus only. Photopic contrast sensitivity was significantly better binocularly than monocularly at all spatial frequencies. Halometry showed a glare scotoma of a mean size similar to that in previous studies of multifocal and accommodating IOLs; there were no subjective complaints of dysphotopsia. The mean NAVQ Rasch score for satisfaction with near vision was 15.9 ± 10.7 logits. Conclusions - The trifocal IOL implanted binocularly produced good distance visual acuity and near and intermediate visual function. Patients were very satisfied with their uncorrected near vision.

Influence of spherical intraocular lens implantation and conventional laser in situ keratomileusis on peripheral ocular aberrations

Aim: To measure the influence of spherical intraocular lens implantation and conventional myopic laser in situ keratomileusis on peripheral ocular aberrations. Setting: Visual & Ophthalmic Optics Laboratory, School of Optometry & Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. Methods: Peripheral aberrations were measured using a modified commercial Hartmann-Shack aberrometer across 42° x 32° of the central visual field in 6 subjects after spherical intraocular lens (IOL) implantation and in 6 subjects after conventional laser in situ keratomileusis (LASIK) for myopia. The results were compared with those of age matched emmetropic and myopic control groups. Results: The IOL group showed a greater rate of quadratic change of spherical equivalent refraction across the visual field, higher spherical aberration, and greater rates of change of higher-order root-mean-square aberrations and total root-mean-square aberrations across the visual field than its emmetropic control group. However, coma trends were similar for the two groups. The LASIK group had a greater rate of quadratic change of spherical equivalent refraction across the visual field, higher spherical aberration, the opposite trend in coma across the field, and greater higher-order root-mean-square aberrations and total root-mean-square aberrations than its myopic control group. Conclusion: Spherical IOL implantation and conventional myopia LASIK increase ocular peripheral aberrations. They cause considerable increase in spherical aberration across the visual field. LASIK reverses the sign of the rate of change in coma across the field relative to that of the other groups. Keywords: refractive surgery, LASIK, IOL implantation, aberrations, peripheral aberrations

Cataract surgery in eyes with low corneal astigmatism : implantation of the AcrySof IQ Toric SN6AT2 intraocular lens

Purpose The aim of this study is to assess the refractive and visual outcomes following cataract surgery and implantation of the AcrySof IQ Toric SN6AT2 intraolcular lens (IOL) (Alcon Laboratories, Inc) in patients with low corneal astigmatism. Materials and Methods A retrospective, consecutive, single surgeon series of ninety-eight eyes of 88 patients following cataract surgery and implantation of the AcrySof IQ Toric SN6AT2 IOL in eyes with low preoperative corneal astigmatism. Postoperative measurements were obtained at one month post surgery. Main outcome measures were monocular distance visual acuity and residual refractive astigmatism. Results The mean preoperative corneal astigmatic power vector (APV) was 0.38 ± 0.09 D. Following surgery and implantation of the toric IOL, mean postoperative refractive APV was 0.13 ± 0.10 D. Mean postoperative distance uncorrected visual acuity (UCVA) was 0.08 ± 0.09 logMAR. Postoperative spherical equivalent refraction (SER) resulted in a mean of - 0.23 ± 0.22 D, with 96% of eyes falling within 0.50 D of the target SER. Conclusions The AcrySof IQ Toric SN6AT2 IOL is a safe and effective option for eyes undergoing cataract surgery with low amounts of preoperative corneal astigmatism.

The intraocular lens: challenges in the prevention and therapy of infectious endophthalmitis and posterior capsular opacification

Cataract is the leading cause of visual impairment worldwide. In the UK, some 30% of the population over 65 years of age have visually impairing cataract. Importantly, 88% of those with treatable visual impairment from cataract are not in contact with any ocular healthcare service, representing a major potential healthcare need [1]. In the USA, it has been estimated that 17.2% of the population (approximately 20.5 million) over 40 years of age have cataract in either eye and by 2020, this number is expected to rise to 30.1 million. Currently, cataract is responsible for 60% of Medicare costs associated with vision [2]. Furthermore, as the populations of industrialized countries such as the UK and the USA continue to age, the costs associated with treatment of cataract can only be expected to increase. Consequently, the development of the intraocular lens to replace the cataractous lens and the advances in intraocular lens design and implantation represent a major development in cataract treatment. However, despite such advances, cataract surgery is not without complications, such as postoperative infectious endophthalmitis, a rare but potentially devastating condition, and posterior capsular opacification, a less serious but much more common problem. This review will examine the epidemiology of cataracts, the polymeric construction of intraocular lenses implanted during cataract surgery and the complications of postoperative infectious endophthalmitis and posterior capsular opacification with regard to therapeutic interventions and prophylactic strategies. Advances in biomaterial design and function will be discussed as novel approaches to prevent such postoperative complications.

Novel Porphyrin-Incorporated Hydrogels for Photoactive Intraocular Lens Biomaterials

Novel surface-modified hydrogel materials have been prepared by binding charged porphyrins TMPyP (tetrakis-(4-N-methylpyridyl)porphyrin) and TPPS (tetrakis(4-sulfonatophenyl)porphyrin) to copolymers of HEMA (2-hydroxyethyl methacrylate) with either MAA (methacrylic acid) or DEAEMA (2-(diethylamino)ethylmethacrylate). The charged hydrogels display strong electrostatic interactions with the appropriate cationic or anionic porphyrins to give materials which are intended to be used to generate cytotoxic singlet oxygen (1O2) on photoexcitation and can therefore be used to reduce postoperative infection of the intraocular hydrogel-based replacement lenses that are used in cataract surgery. The UV/vis spectra of TMPyP in MAA:HEMA copolymers showed a small shift in the Soret band and a change from single exponential (161 ���­s) triplet decay lifetime in solution to a decay that could be fitted to a biexponential fit with two approximately equal components with ���´ ) 350 and 1300 ���­s. O2 bubbling reduced the decay to a dominant (90%) component with a much reduced lifetime of 3 ���­s and a minor, longer lived (20 ���­s) component. With D2O solvent the 1O2 lifetime was measured by 1270 nm fluorescence as 35 ���­s in MAA:HEMA, compared to 67 ���­s in solution, although absorbance-matched samples showed similar yield of 1O2 in the polymers and in aqueous solution. In contrast to the minor perturbation in photophysical properties caused by binding TMPyP to MAA:HEMA, TPPS binding to DEAEMA:HEMA copolymers profoundly changed the 1O2 generating ability of the TPPS. In N2-bubbled samples, the polymer-bound TPPS behaved in a similar manner to TMPyP in its copolymer host; however, O2 bubbling had only a very small effect on the triplet lifetime and no 1O2 generation could be detected. The difference in behavior may be linked to differences in binding in the two systems. With TMPyP in MAA:HEMA, confocal fluorescence microscopy showed significant penetration of the porphyrin into the core of the polymer film samples (>150 ���­m). However, for TPPS in DEAEMA:HEMA copolymers, although the porphyrin bound much more readily to the polymer, it remained localized in the first 20 ���­m, even in heavily loaded samples. It is possible that the resulting high concentration of TPPS may have cross-linked the hydrogels to such an extent that it significantly reduced the solubility and/or diffusion rate of oxygen into the doped polymers. This effect is significant since it demonstrates that even simple electrostatic binding of charged porphyrins to hydrogels can have an unexpectedly large effect on the properties of the system as a whole. In this case it makes the apparently promising TPPS/DEAEMA:HEMA system a poor candidate for clinical application as a postoperative antibacterial treatment for intraocular lenses while the apparently equivalent cationic system TMPyP/MAA:HEMA displays all the required properties.