Aspheric Intraocular Lens Research Articles

Effect of haptic geometry in C-loop intraocular lenses on optical quality

The biomechanical stability of intraocular lenses (IOLs) must achieve high-quality optical performance and clinical outcomes after cataract surgery. For this reason, the quality and performance features of the IOLs should be previously analysed following the Standard ISO 11979-2 and ISO 11979-3. The ISO 11979-3 tries to reproduce the behaviour of the IOL in the capsular bag by compressing the lens between two clamps. With this test, it has been demonstrated that the haptic design is a crucial factor to obtain biomechanical stability. Hence, the main goal of this study was to design an aberration-free aspheric IOL and to study the influence of haptic geometry on the optical quality. For that purpose, 5 hydrophobic IOLs with different haptic design were manufactured and their biomechanical stability was compared experimentally and numerically. The IOLs were classified as stiff and flexible designs depending on their haptic geometry. The biomechanical response was measured by means of the compression force, the axial displacement, the angle of contact or contact area, the decentration, the tilt and the strain energy. The results suggest that in vitro and in silico compression tests present similar responses for the IOLs analysed. Furthermore, the flexible IOL designs presented better biomechanical stability than stiff designs. These results were correlated with the optical performance, where the optical quality decreases with worst biomechanical stability. This numerical methodology provides an indisputable advance regarding IOL designs, leading to reduce costs by exploring a feasible space of solutions during the product design process and prior to manufacturing.

Comparison of Optical Quality, Spherical Aberration and Contrast Sensitivity between Spherical and Aspheric Intraocular Lenses

Comparison of Optical Quality, Spherical Aberration and Contrast Sensitivity between Spherical and Aspheric Intraocular Lenses

Comparison of the Visual Performance after Implantation of Three Aberration-correcting Aspherical Intraocular Lens

ABSTRACT Purpose To compare the visual performance after implantation of three aberration-correcting aspherical intraocular lens (IOL). Materials and Methods Seventy-seven eyes of 77 cataract patients were divided into three groups: 26 eyes implanted with a non-constant aberration IOL (LUCIA 601P IOL, Zeiss Company, Germany); 26 eyes implanted with a spherical aberration −0.18μm IOL (CT ASPHINA 509M, Zeiss Company, Germany) and 27 eyes implanted with a spherical aberration −0.27μm IOL (AMO Tecnis ZCB00, Johnson & Johnson Surgical Vision, USA). Three months after operation, the distance visual acuity, wavefront aberrometry, contrast sensitivity, intraocular stray light, IOL decentration, and tilt were evaluated. Results Three months postoperatively, no statistically significant differences were found in uncorrected distance visual acuity and corrected distance visual acuity (p≥.83). The RMS for total ocular coma was statistically significantly lower in the Lucia group (p=.03) and spherical aberration was statistically significantly lower in the Tecnis group (p<.01). No statistically significant differences were observed among the three lenses in higher order aberration (p=.85) and in contrast sensitivity under both photopic and mesopic lighting conditions (p≥.05). The intraocular stray light was statistically significantly better in the Lucia group (p=.04). No statistically significant differences were observed with respect to IOL decentration (p=.75) and tilt (p=.89). Conclusions Cataract surgery with non-constant aberration IOL resulted in lower coma and better intraocular stray light than with the spherical aberration −0.18μm and −0.27μm IOLs despite equivalent postoperative levels of visual acuity and contrast sensitivity.

Long-Term Visual Quality after Microincision Cataract Surgery.

Purpose Few studies have focused on long-term postoperative visual quality. This study aimed to evaluate the long-term visual quality after microincision cataract surgery (MICS). Methods 96 patients (144 eyes) diagnosed with age-related cataracts were enrolled in this one-year study. The patients underwent MICS and received aspheric monofocal intraocular lens implants. Uncorrected distance visual acuity (UDVA) was evaluated together with best-corrected distance visual acuity (BCDVA), best-corrected near visual acuity (BCNVA), contrast sensitivity, and surgically induced astigmatism (SIA). Results Compared to preoperative measurements, UDVA, BCDVA, and BCNVA were significantly better after surgery (P < 0.001), and they remained stable throughout follow-up. Contrast sensitivity was also significantly better after surgery (P < 0.001). Mean SIA during follow-up was 0.57 ± 0.33 D at 1 week, 0.36 ± 0.25 D at 3 months, and 0.18 ± 0.16 D at 1 year. SIA decreased significantly during the postoperative period (P < 0.001). The 1-year postoperative absolute residual diopter value was 0.32 ± 0.28 D. Conclusion MICS can provide excellent visual quality as soon as on postoperative day 1, which persists during the follow-up period of 1 year. In contrast to previous studies, SIA decreases over time and may not completely stabilize for as long as 1 year postoperatively.

Effect of Intraocular Lens Tilt and Decentration on Visual Acuity, Dysphotopsia and Wavefront Aberrations.

Tilt and decentration of intraocular lenses (IOL) may occur secondary to a complicated cataract surgery or following an uneventful phacoemulsification. Although up to 2–3° tilt and a 0.2–0.3 mm decentration are common and clinically unnoticed for any design of IOL, larger extent of tilt and decentration has a negative impact on the optical performance and subsequently, the patients’ satisfaction. This negative impact does not affect various types of IOLs equally. In this paper we review the methods of measuring IOL tilt and decentration and focus on the effect of IOL tilt and decentration on visual function, in particular visual acuity, dysphotopsia, and wavefront aberrations. Our review found that the methods to measure the IOL displacement have significantly evolved and the available studies have employed different methods in their measurement, while comparability of these methods is questionable. There has been no universal reference point and axis to measure the IOL displacement between different studies. A remarkably high variety and brands of IOLs are used in various studies and occasionally, opposite results are noticed when two different brands of a same design were compared against another IOL design in two studies. We conclude that <5° of inferotemporal tilt is common in both crystalline lenses and IOLs with a correlation between pre- and postoperative lens tilt. IOL tilt has been noticed more frequently with scleral fixated compared with in-the-bag IOLs. IOL decentration has a greater impact than tilt on reduction of visual acuity. There was no correlation between IOL tilt and decentration and dysphotopsia. The advantages of aspheric IOLs are lost when decentration is >0.5 mm. The effect of IOL displacement on visual function is more pronounced in aberration correcting IOLs compared to spherical and standard non-aberration correcting aspherical IOLs and in multifocal versus monofocal IOLs. Internal coma has been frequently associated with IOL tilt and decentration, and this increases with pupil size. There is no correlation between spherical aberration and IOL tilt or decentration. Although IOL tilt produces significant impact on visual outcome in toric IOLs, these lenses are more sensitive to rotation compared to tilt.

Reply

We are pleased by the interest elicited by our work.1 To deal with a new intraocular lens (IOL) implies several considerations that cannot be summarized in only 1 preliminary study. Our main goal in this publication was to compare the clinical outcomes of this new monofocal IOL, Tecnis Eyhance ICB00, to a well-known monofocal aspheric IOL, TECNIS ZCB00.1 The 2 IOLs share the same material and platform and the same chromatic aberration and spherical aberration (SA) (−0.27 μm for 6 mm aperture).2 The Tecnis Eyhance IOL increases depth of focus due to a higher-order aspheric anterior surface with a continuous and localized increase in power from the periphery to the center of the IOL. This is a fundamentally different approach than using SA to extend the depth of focus. Primarily, SA affects the power by a factor of r2, where r is the radius of the pupil. It is for this reason that the effects of primary SA are heavily noticeable for larger pupil sizes, with an increase in the depth of focus and decrease in distance vision quality. This was confirmed by a preclinical study based on clinically relevant metrics, which compared the outcomes provided by TECNIS Eyhance IOL with monofocal IOLs with different aspheric designs and different levels of SA and chromatic aberration.3,4 While TECNIS Eyhance IOL provided improvement in intermediate vision and maintained the distance image quality of an aspheric monofocal IOL, independently of the pupil size, the spherical IOL demonstrated a pupil-dependent behavior: it improved intermediate simulated vision and decreased distance image quality for large pupils, whereas, for small pupils, its performance was similar to an aspheric IOL.4 Therefore, because the depth of focus is not increased through a modification of the SA of the Eyhance IOL, we do not expect that eventual corneal SA and pupil size differences between the 2 groups of patients would affect the outcomes of our study, as suggested by Vamosi and Nemeth.1 We also think that, in a preliminary study, the comparison of 2 IOLs of the same platform adds more value than the comparison of IOLs with different designs and materials. Nevertheless, the suggestion to compare the intermediate vision outcomes of Tecnis Eyhance IOL with those of other monofocal IOLs such as SA-free aspheric IOLs is intriguing and would merit future studies. Regarding the remark about mesopic contrast sensitivity, we clearly stated in the discussion of our article, “in future studies, it could be interesting to compare the mesopic contrast sensitivity between the Eyhance ICB00 IOL and the ZCB00 IOL” and with other monofocal IOLs.1 Of interest, the mesopic contrast sensitivity is a well-known strength of the Tecnis IOL platform.5 We agree that further investigations are necessary to assess whether the new approach of the Tecnis Eyhance IOL represents a step forward in investigating the still little-explored field of intermediate vision.

Matching the Patient to the Intraocular Lens: Preoperative Considerations to Optimize Surgical Outcomes

The intraocular lens (IOL) selection process for patients requires a complex and objective assessment of patient-specific ocular characteristics, including the quality and quantity of corneal astigmatism, health of the ocular surface, and other ocular comorbidities. Potential issues that could be considered complications after surgery, including dry eye disease, anterior or epithelial basement membrane dystrophy, Salzmann nodular degeneration, and pterygium, should be addressed proactively. Aspheric IOLs are designed to eliminate the positive spherical aberration added by traditional IOLs to the pseudophakic visual axis. Spherical aberration may be a consideration with patient selection. Patient desire for increased spectacle independence after surgery is one of the main drivers for the development of multifocal IOLs and extended depth-of-focus (EDOF) IOLs. However, no one single multifocal or EDOF IOL suits all patients' needs. The wide variety of multifocal and EDOF IOLs, their optics, and their respective impact on patient quality of vision have to be understood fully to choose the appropriate IOL for each individual, and surgery has to be customized. Patients who have undergone previous LASIK or who have radial keratotomy and ocular pathologic features, including glaucoma, age-related macular degeneration, and epiretinal membrane, require specific considerations for IOL selection. Subjectively, patient-centered considerations, including visual goals, lifestyle, personality, profession, and hobbies, are key elements for the surgeon to assess and factor into an IOL recommendation. This holistic approach will help surgeons to achieve optimal surgical outcomes and to meet (and exceed) the high expectations of patients.

Enhancing the Intermediate Vision of Monofocal Intraocular Lenses Using a Higher Order Aspheric Optic.

To describe and evaluate a new monofocal intraocular lens (IOL) designed to improve intermediate vision using a unique refractive technology. The new monofocal lens is based on a higher order aspheric optic and is designed to improve intermediate vision. Simulated visual acuity from far to -2.00 diopters (D) was calculated using optical bench data. The effect of corneal higher order aberrations (HOAs) on simulated visual acuity, pupil size, and decentration was assessed using realistic computer eye models. The susceptibility to photic phenomena was evaluated by measuring preclinically the intensity of the light distribution in the retinal plane. The new lens design was compared to a standard aspheric monofocal IOL that shares the same platform, material, and primary spherical aberration as the new design. Simulated defocus curves showed increased simulated visual acuity in the intermediate range compared to a standard aspheric monofocal IOL with comparable distance vision, independently of the pupil size and corneal HOAs. At -1.50 D, the new IOL design provided a gain of approximately 0.1 logMAR, whereas at distance, the difference was less than 0.05 logMAR. The tolerance to decentration was also similar in both designs. Finally, experimental results indicate that the susceptibility to photic phenomena with the new lens design was similar to that of a standard aspheric monofocal IOL. Preclinical data showed that the new lens design improves intermediate vision while maintaining comparable distance image quality and keeping the same photic phenomena profile as a standard aspheric monofocal IOL. [J Refract Surg. 2020;36(8):520-527.].

Surface profiles of new-generation IOLs with improved intermediate vision.

To evaluate the surface profile of different new-generation intraocular lenses (IOLs) designed to improve intermediate vision. Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy. Prospective experimental laboratory study. One higher-order aspheric monofocal IOL (Tecnis Eyhance ICB00) and 2 extended depth-of-focus (EDOF) IOLs (Tecnis Symfony ZXR00, Mini Well Ready) were examined and compared with monofocal IOLs with the same platform (Sensar AAB00, Tecnis ZCB00, Mini 4 Ready) using contact profilometry. Raw profiles were obtained and compared. The best-fit circle was then subtracted from each raw profile to highlight differences. The new higher-order aspheric IOL presented a peculiar profile, which appeared similar to the conventional monofocal IOL based on the same platform, with just minimal differences in the central design. One of the EDOF IOLs showed a diffractive design. The EDOF IOL based on spherical aberration presented a central steepening surrounded by a symmetric lateral change in depths. Improved intermediate vision can be achieved by means of different optic designs. Unlike the traditional EDOF and multifocal IOLs based on a diffractive design, the profiles of new-generation IOLs are characterized by smooth and progressive changes of the superficial geometry.

Static and Dynamic Factors Associated With Extended Depth of Focus in Monofocal Intraocular Lenses

To analyze factors affecting depth of focus (DOF) and near vision functionality in eyes implanted with aspheric monofocal intraocular lenses (IOLs). This prospective study included 111 eyes of 74 patients that underwent phacoemulsification with monofocal IOL implantation. Ninety-one normal eyes were randomized to receive aberration-free (n= 30) or negative-spherical aberration (SA) IOLs (n= 61). Twenty post-hyperopic femto-LASIK eyes received aberration-free IOLs. Corneal higher-order aberrations (SA, coma, trefoil, and corneal asphericity) for a 6mm pupil were measured by Scheimpflug tomography. Ray-tracing metrics (visual Strehl optical transfer function [VSOTF], effective range of focus [EROF], sphere shift [SS], EROF-SS), pupil size measurements at far and near, and ocular and corneal SA were obtained using ray-tracing aberrometry. Distance-corrected near visual acuity (DCNVA) and subjective defocus curves up to ±4.0 diopters were evaluated. Multivariable logistic regression found corneal profile and IOL type to be determinants of extended DOF with monofocal IOLs. The aberration-free IOL group showed significantly better DCNVA and higher total SA than the negative-SA group. Post-hyperopic LASIK eyes showed significantly better DCNVA; higher negative SA, coma, and Q value (P < .05), and smaller pupil size (P= .05) than normal eyes implanted with aberration-free IOLs. Corneal profile and type of IOL implanted were the most important factors influencing near vision functionality with aspheric monofocal IOLs. Higher positive SA in the aberration-free group potentially led to better DCNVA than the negative-SA group in normal eyes. Hyperprolate corneas had better DOF curves and DCNVA than normal corneas. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Extended Depth of Focus Versus Monofocal IOLs: Objective and Subjective Visual Outcomes.

To evaluate and compare the objective and subjective outcomes between bilateral implantation of the extended depth of focus (EDOF) Mini Well intraocular lens (IOL) and the aspheric monofocal Mini-4-Ready IOL (both SIFI S.p.A., Catania, Italy). This prospective comparative study included 25 patients (50 eyes) bilaterally implanted with an EDOF Mini Well IOL (EDOF group) and 25 patients (50 eyes) bilaterally implanted with a Mini-4-Ready IOL (monofocal group). Three-month follow-up data included corrected and uncorrected distance visual acuity at 4 m and 80, 67, and 40 cm. Defocus curves, subjective and objective contrast sensitivity, and objective optical quality (modulation transfer function cutoff and Strehl ratio calculated with Optical Quality Analysis System [OQAS]; Visiometrics SL, Terrassa, Spain), halometry, and reading performance were measured. Subjective visual quality was evaluated based on National Eye Institute Refractive Error Quality of Life Instrument 42 (NEI RQL-42) scores. Postoperative uncorrected and corrected monocular and binocular intermediate and near visual acuity was significantly better in the EDOF group (P < .001). No differences were observed for distance visual acuity (P ⩾ .312). Defocus curve outcomes for myopic values were better in the EDOF group (P < .001). No significant differences were found in hyperopic (obtained in steps of +0.50 diopters [D] from emmetropia to 1.50 D) values (P ⩾ .095), contrast sensitivity curves (P ⩾ .087), or OQAS outcomes (P ⩾ .138). Halometric values were significantly better in the monofocal group (P < .05). There was a correlation between mean keratometry values and intermediate/near visual acuity. Significantly better NEI RQL-42 subscale scores for near vision, far vision, activity limitations, glare, dependence on correction, and suboptimal correction were noted in the EDOF group (P < .05). Intermediate and near visual acuity was better after EDOF IOL than after aspheric monofocal IOL implantation while maintaining similar levels of visual quality, except for halo perception. [J Refract Surg. 2020;36(4):214-222.].

Interaction of Monochromatic and Chromatic Aberrations in Pseudophakic Patients.

To measure monochromatic aberrations at various wavelengths in eyes implanted with the Clareon monofocal aspheric intraocular lens (IOL) (Alcon Laboratories, Inc., Fort Worth, TX). The authors estimated longitudinal chromatic aberration (LCA), modulation transfer functions (MTFs), and the impact of interactions between chromatic and monochromatic aberrations on retinal image quality. Ten patients (age: 68.4 ± 3.21 years) were measured in two experiments: (1) Hartmann-Shack wave aberrations at five visible wavelengths (480 to 700 nm) and (2) best subjective focus at each wavelength. Objective and psychophysical LCAs were obtained from the Zernike defocus and psychophysical best focus, respectively. MTFs were calculated for the closest wavelengths to the peak sensitivity of the three cone classes (S [480 nm], M [555 nm], and L [564 nm]) using the measured aberrations and chromatic difference of focus. The degradation produced by LCA was estimated as the visual Strehl ratio for green divided by the visual Strehl ratio for blue and red. The root mean square for higher order aberrations (HOAs) ranged from 0.0622 to 0.2084 µm (700 nm, 4.3-mm pupil). Monochromatic visual Strehl ratio was above 0.35 in all patients. LCA was 1.23 ± 0.05 diopters (D) (psychophysical) and 0.90 ± 0.11 D (objective). Visual Strehl ratio decreased by a factor ranging from 1.38 to 3.82 on chromatic defocus from green to blue. There was a significant correlation between native visual Strehl ratio and the degradation produced by LCA (ie, visual Strehl555/visual Strehl480). The Clareon IOL compensates for spherical aberration, with postoperative wave aberrations dominated by astigmatism and other HOAs, being highly subject-dependent. The impact of LCA in blue is largely dependent on the magnitude of monochromatic aberrations. [J Refract Surg. 2020;36(4):230-238.].

Prospective Comparison of Intraocular Lens Dynamics and Refractive Error between Phacovitrectomy and Phacoemulsification Alone

To compare intraocular lens (IOL) dynamics and refractive prediction errors between eyes that underwent phacovitrectomy and eyes that underwent phacoemulsification alone. Prospective, nonrandomized, comparative, observational study. Sixty eyes of 60 patients who underwent 25-gauge phacovitrectomy without gas injection for macular pathology and 60 eyes of 60 patients who underwent phacoemulsification alone for cataract were enrolled. Preoperative optical biometry was performed using the IOLMaster 700 (Carl Zeiss Meditec, Inc, Dublin, CA) to calculate the IOL power with the Barrett Universal II formula. Monofocal, nontoric, single-piece foldable aspherical IOLs were implanted in each patient. Comprehensive ocular examinations, including CASIA2 (Tomey Corp, Nagoya, Japan) evaluations of the preoperative crystalline lens and postoperative IOL positions (i.e., decentration, tilt, and aqueous depth), were performed before and 3 days, 1 month, and 3 months after surgery. Refractive prediction errors and IOL dynamics. Mean refractive prediction errors at 3 days, 1 month, and 3 months after phacovitrectomy were 0.51±0.59 diopters (D), 0.11±0.40 D, and 0.05±0.41 D, respectively, whereas those after phacoemulsification alone were 0.43±0.38 D, 0.11±0.37 D, and 0.07±0.34 D, respectively. There was no significant difference in the refractive error between the 2 groups at any time point. A myopic shift of-0.50 D or more negative refractive error occurred in 4 (6.7%) of 60 eyes with phacovitrectomy and 3 (5.0%) of 60 eyes with phacoemulsification alone; there was no significant between-group difference. At 3 months postoperatively, refractive errors within ±0.50 D and ±1.00 D were achieved in 49 (81.7%) and 58 (96.7%) of 60 eyes in the phacovitrectomy group and 52 (86.7%) and 60 (100.0%) of 60 eyes in the phacoemulsification alone group, again without any significant between-group differences. There were no significant differences in the preoperative lens and postoperative IOL positions between the 2 study groups, except for a significantly deeper mean aqueous depth at 3 days after surgery in the phacovitrectomy group. Neither myopic shift nor IOL displacement occurs after 25-gauge phacovitrectomy with a single-piece IOL without gas injection for macular pathology compared with phacoemulsification alone.

Comparison of Toric Intraocular Lens Alignment Using Image-Guided System and Manual Marking Technique.

Objectives:The aim of this study was to compare the accuracy of an image-guided system (Callisto eye; Carl Zeiss, Oberkochen, Germany) with the manual marking technique in the positioning of a toric intraocular lens (IOL).Methods:A total of 80 eyes of 80 patients who underwent cataract surgery with a monofocal, single-piece, hydrophobic, biconvex, toric, aspheric IOL (Acrysof IQ SN6AT, Alcon Laboratories, Inc., Fort Worth, TX, USA) implantation were included. Before surgery, all of the patients underwent a complete eye examination that included evaluation of uncorrected (UCVA) and corrected distance visual acuity (CDVA), spherical equivalent (SE), astigmatic refraction (AR), keratometry, biometry, as well as meridian registration with the IOLMaster 700 (Carl Zeiss, Oberkochen, Germany), slit lamp examination, intraocular pressure measurement, and dilated retinal examination. The diopter of the toric IOL was calculated with an online calculator (Alcon, Fort Worth, TX, USA). At 3 months post surgery, the UCVA, CDVA, SE, and residual astigmatism were recorded, and the pupils of all of the patients were fully dilated to determine the toric IOL marker positions.Results:Group 1, the Callisto eye system group, comprised 45 eyes, and Group 2, the manual marking technique group, was composed of 35 eyes. The preoperative values of both groups were statistically similar in terms of the SE, corneal cylinder, axial length, logMAR UDVA, and logMAR CDVA. At postoperative 3 months, there were no significant differences between the 2 groups in the logMAR UDVA, logMAR CDVA, degree of misalignment of toric IOL, or mean deviation from target-induced astigmatism values. The mean deviation degree from the intended axis was 2.04±1.84 in the Callisto eye system group (Group 1) and 3.24±2.64 in the manual marking technique group (Group 2). However, this difference did not have any effect on the logMAR UDVA.Conclusion:The image-guided markerless system was found to be as effective as manual marking in the positioning of toric IOLs.

Pupillodynamics and corneal spherical aberrations in a set of Indian cataract patients and its implications for aberrometric customisation of intraocular lenses.

Purpose:Assessment of pupil diameter in various light conditions and the corresponding corneal spherical aberrations in a cohort of Indian eyes with bilateral senile cataracts and the possible use of this data in aberrometric customization of intraocular lenses (IOLs).Methods:In this prospective observational study done at a tertiary eye care centre in India, the selected patients were subjected to measurement of their pupil diameters in scotopic, mesopic, and photopic conditions as well as the corresponding corneal spherical aberrations, using the Sirius Topographer (Costruzione Strumenti Oftalmici, Florence, Italy). Shapiro–Wilk test, Independent t-test, ANOVA with Bonferroni correction on post-hoc testing were used for statistical analysis.Results:104 eyes of 52 patients were enrolled for the study. The mean age was 53 ± 11.88 years. The mean scotopic, mesopic, and photopic pupil sizes were 4.37 mm (4.11–4.63 mm), 3.92 mm (3.71 mm–4.15 mm), and 3.37 mm (3.18–3.67 mm), respectively. There was a statistically significant difference (P = <0.001) in the mean corneal spherical aberration measured at the 6 mm zone (0.23 ± 0.02 microns) and at the 4 mm zone (0.06 ± 0.01 microns).Conclusion:The mean corneal spherical aberration corresponding to the average mesopic pupil size of our patient population was substantially lower than that of the scotopic pupil size and also less than the amount corrected by most of the negative aspheric IOLs. This perhaps indicates the need for customising IOLs based on the spherical aberrations of cornea at the zone corresponding to the mesopic pupil diameter for optimal residual total postoperative spherical aberrations.

Personalized aspheric intraocular lens implantation based on corneal spherical aberration: a review.

With the evolution of cataract surgery from visual rehabilitation to refractive surgery, aspheric intraocular lenses (IOLs) are being increasingly used in the field of ophthalmology. This increased use can be attributed to negative or zero spherical aberrations with unique optical designs, which counteract some of the positive spherical aberrations of the cornea. These alterations reduce the total spherical aberration of human eyes and improve the visual acuity in patients with cataract postoperatively. At present, various types of aspheric IOLs are used worldwide. Although the implantation of aspheric IOL is beneficial to the patients who need correction of spherical aberrations, much controversy is still associated with ocular residual spherical aberrations that facilitate the best visual quality for patients postoperatively. In order to provide reference for future clinical work and scientific research, this report reviews the relationship between the ocular residual spherical aberration of human eyes and visual quality.

Comparison of three different diffractıve multifocal intraocular lenses with a +2.5, +3.0, and +3.75 diopter additıon power

PurposeTo compare the functional outcomes and astigmatic tolerability after implantation of multifocal intraocular lenses (IOLs) with a +2.5, +3.0, and +3.75 diopter (D) addition power. MethodsThis study included 122 eyes of 61 patients who had bilateral cataract extraction and implantation of diffractive aspheric multifocal acrylic IOLs with +2.5 D (+2.5 group), +3.0 D (+3.0 group), and +3.75 D (+3.75 group) addition powers. 1-year after surgery, distance corrected near (DNVA) and intermediate (DIVA) visual acuities at 32, 40, 45, 50, 55, and 60 cm; and contrast sensitivity measurements under photopic, mesopic and mesopic with glare conditions; spherical and astigmatic defocus testing; distance-intermediate-near vision patient satisfaction levels; spectacle dependance; patient-reported outcomes were assessed binocularly. ResultsThe +2.50 D group had better DIVA than both +3.0 group and +3.75 groups at 45 cm, 50 cm, 55 cm, and 60 cm (p < 0.05). The +3.75 group had better DNVA than both +2.5 and +3.0 IOL groups at 32 cm (p < 0.05). There was no significant difference in mean contrast values at all frequencies between three IOL groups (p > 0.05). The +2.50 D group showed better astigmatic tolerability than +3.00 group (at 2.00 D) and +3.75 group (at 1.50 D, and at 2.00 D) (p < 0.05). ConclusionMultifocal IOLs with +2.5 add power have better intermediate vision, but worse near vision compared to multifocal IOLs with +3.00 D and +3.75 D add power. Multifocal IOLs with +2.50 D add power tend to have better astigmatic defocus tolerability than multifocal IOLs with +3.00 D and +3.75 D add powers.

Distribution of corneal spherical aberration in a Tanzanian population

PurposeTo investigate the distribution of corneal spherical aberration (SA) in Tanzanian people of African descent, and to examine the correlation between corneal SA and ocular parameters.DesignCross-sectional population-based study.MethodsResidents aged 40 years and older in three villages in the Mkuranga district in Tanzania were enlisted as study participants. Corneal higher-order aberrations (HOAs) for the right eye were measured with a wavefront analyzer (KR-1W, Topcon) and calculated for the central 6.0-mm zone. Corneal curvature radius (CR), corneal astigmatism, and axial length (AL) were also measured and their correlation with corneal SA was assessed.ResultsThe right eyes of 657 participants (336 male, 321 female) were analyzed. The mean age of the subjects was 57.2 ± 10.3 years (mean ± SD). The mean corneal SA (Zernike spherical aberration coefficient C40) was 0.188 ± 0.095 μm (-0.242 to 0.613). The SAs in about three-quarters of all subjects were between 0.10 and 0.30 μm. The root mean squares of total corneal HOAs and the third- and fourth-order aberrations were 0.629 ± 0.250 μm, 0.539 ± 0.236 μm, and 0.269 ± 0.110 μm, respectively. Corneal SA showed weak significant correlations with CR (Spearman’s rank correlation coefficient, r = -0.177, p < 0.001), corneal astigmatism (r = -0.142, p < 0.001), AL (r = -0.168, p < 0.001), and age (r = -0.085, p < 0.05).ConclusionsThis finding may be beneficial for selecting aspheric intraocular lens in this population.

Visual Function after Implantation of a Presbyopia-Correcting Trifocal Intraocular Lens

Purpose: To evaluate distance, intermediate, and near visual performance in patients implanted with a trifocal aspheric presbyopia-correcting intraocular lens (IOL). Methods: Forty patients were bilaterally implanted with the AcrySofIQ PanOptix IOL after femtosecond laser-assisted lens surgery. Binocular best corrected distance visual acuity (CDVA) (4 m), best distance-corrected near visual acuity (DCNVA) (40 and 30 cm), best corrected distance intermediate visual acuity (DCIVA) (70, 60, and 50 cm), binocular distance contrast sensitivity under photopic conditions (85 cd/m²), and defocus curves were evaluated at 6-months. Results: Six months postoperatively, the mean binocular Snellen decimal CDVA and DCNVA were 0.94 ± 0.10 (ranging from 0.70 to 1.25) and 0.85 ± 0.13 (ranging from 0.63 to 1.00), respectively. At a distance, all patients showed a cumulative binocular distance-corrected visual acuity of 0.8 or better, and about 80% (n = 31) of the patients had a value of 1.0 (20/20). At near and intermediate distances, all patients showed a cumulative distance-corrected visual acuity of 0.5 (20/40) or better at 30, 40, 50, 60, and 70 cm. Specifically, 50 cm showed the highest percentage of patients with larger values of visual acuity (60% [n = 26] with 20/20). Defocus curve showed a wide range of useful vision with two peaks of best visual acuity at distance and at 50 cm, and the binocular distance contrast sensitivity was within normal limits. Conclusions: The outcomes of the present study show that the visual performance obtained with bilateral implantation of the trifocal aspheric AcrySofIQ PanOptix IOL is good at far, intermediate, and near distances.

Predictive value of intracrystalline interphase point measured by optical low-coherence reflectometry for the estimation of the anatomical position of an intraocular lens after cataract surgery

To investigate the predictive value of the intracrystalline interphase point (ICIP) measured with optical low-coherence reflectometry (OCLR) to estimate the final lens position (FLP) of an intraocular lens (IOL) after cataract surgery. Alcañiz Hospital, Teruel, Spain. Single-center retrospective descriptive study. Patients undergoing cataract surgery were enrolled. They were grouped according to the IOL implanted as follows: Group 1, Acrysof IQ aspheric SN60WF IOL (77 eyes); Group 2, enVista MX60 IOL (71 eyes); Group 3, CT Asphina 409 IOL (44 eyes). An OCLR-based biometer (Lenstar LS 900 system) was used for biometric measurements preoperatively and at 4 to 5weeks postoperatively. The study comprised 192 eyes of 174 patients (mean age: 76.4years). One hundred seventy eyes (88.5%) eyes showed an absolute refractive prediction error (ARPE) less than 0.50 diopters (D). The mean ARPE was 0.25 D ± 0.21 (SD). Significantly higher FLP values were found in Group 2 compared with the other two groups (P<.001). Significantly lower ICIP values were found in the eyes with an ARPE of 0.50 D or more compared with eyes that had an ARPE less than 0.50 D in Group 1 (P=.042) and Group 2 (P=.023). The correlation of the FLP with the ICIP was good in all three groups (r≥0.74, P <.001). Three linear expressions were obtained to predict the FLP from the ICIP and other preoperative data (R2: 0.85, 0.69, and 0.49 in Groups 1, 2, and 3, respectively). The position of the ICIP measured with OCLR correlated with the FLP after cataract surgery, and it can be used to optimize IOL power calculations.