Real and pseudoaccommodation in accommodative lenses

Factors associated with good near vision after cataract surgery with monofocal intraocular lens implantation at a tertiary eye hospital in southern India

PURPOSE

Although multifocal intraocular lenses (IOLs) are effective methods of dealing with surgical presbyopia, there are associated limitations (cost, technique, and patient-reported symptoms). Given their scalability challenge (due to economic factors), it is imperative to explore alternative low-cost and sustainable solutions to achieve good near vision postcataract surgery. This study aimed to determine the proportion of and the factors associated with good near vision in patients following cataract surgery with monofocal IOL implantation.

METHODS

We conducted a hospital-based cross-sectional study at a tertiary eye hospital in southern India from September 2019 to January 2020. Inclusion criteria: Uncomplicated postcataract surgery cases with monofocal IOL at least 30 days ago. Exclusion criteria: patients with any ocular condition (other than refractive errors) that could decrease the vision with best-corrected distance visual acuity < 0.18 Logarithm of the Minimum Angle of Resolution (LogMAR) units. Data collection: we assessed near vision (at 40 cm distance by using near vision card with Early Treatment of Diabetic Retinopathy Study format), distance visual acuity (uncorrected and best-corrected), refractive error (amount and type), type of astigmatism, pupil size, axial length, and contrast sensitivity. We considered a near vision of 0.2 LogMAR units or better as good near vision.

RESULTS

Of the 82 patients (82 eyes), 71 (86.59%) had good near vision. Multiple logistic regression analysis found found that the presence of myopia or myopic astigmatism was significantly associated with good near vision (adjusted odds ratio: 72.63; 95% confidence interval: 1.02-5193.5, p = 0.049).

CONCLUSION

About eight of every ten participants had good near vision postcataract surgery with monofocal IOL implantation. Myopia/myopic astigmatism was associated with good near vision.

Visual outcome and optical quality of a wavefront-engineered extended depth-of-focus intraocular lens

PURPOSE

To evaluate visual performance and optical quality of an extended depth-of-focus intraocular lens (EDoF IOL) compared with a monofocal aspheric IOL.

SETTING

Department of Ophthalmology, Charité-Medical University Berlin, Germany.

DESIGN

Prospective case series.

METHODS

After phacoemulsification, a total of 28 patients (56 eyes) underwent bilateral implantation of either the Mini Well (EDoF IOL) or the Mini 4 (monofocal IOL). Assessments including refraction, distance, intermediate and near visual acuity, defocus curves, contrast sensitivity, glare disability, higher-order aberrations (HOAs), and patient satisfaction were performed at 1 month and 3 months postoperatively.

RESULTS

Both study groups comprised 14 patients (28 eyes) each. At 3-month follow-up, the EDoF IOL showed better results in monocular uncorrected intermediate visual acuity (-0.04 vs 0.10 logMAR, P = .000) and in uncorrected near visual acuity (0.13 vs 0.36 logMAR, P = .000), whereas no statistically significant difference was found between groups in monocular uncorrected distance visual acuity (0.04 vs 0.00 logMAR, P = .110). The monocular depth of focus was 0.8 D greater in the Mini Well IOL group. Measurements of internal HOAs revealed a greater negative primary spherical aberration in the EDoF group at pupil sizes of 2.0 to 5.0 mm. At 5.0 mm, total internal HOAs did not differ statistically significantly (0.376 vs 0.340 μm root mean square, P = .068).

CONCLUSIONS

The Mini Well IOL provided greater depth of focus with superior outcomes at intermediate and near distances and comparable outcomes at far distance. Although inducing higher amounts of spherical aberration, it showed good results under low lighting conditions with little subjective dysphotopsia.

A Glossary for ''Pseudo'' Conditions in Ophthalmology

The term "pseudo'' refers to ''lying, false, fake, simulation, imitation or spurious.'' In ophthalmological literature, there are many diseases/conditions/signs/phenomena that are considered as "pseudo." A literature search was conducted on the Medical Subject Headings website, and the keywords that were searched in the title and abstract were as follows: (pseudo-), (fake), (false), (mimicker), (simulator), (masquerade), AND (condition) AND(causes) AND (ophthalmology)OR (eye) OR (ocular) OR (ophthalmic) OR (cornea) OR (retina) OR (strabismus) OR (glaucoma). The search was restricted to English language. The major databases such as PubMed, Medline, Scopus, Google Scholar, OVID, EBSCO, and Cochrane Library were searched or investigated for information. The objective of this review is to summarize common ''pseudo'' conditions in ophthalmology and their respective common causes. We believe that the knowledge of these pseudo-conditions will provide significant benefits in the differential diagnosis of various ophthalmic disorders.

FOCUSED (Femtosecond Optimized Continuous Uncorrected Sight with EDOF and Diffractive Multifocal IOLs) - A Review

PURPOSE OF REVIEW

The aim of this article is to review techniques to maximize all-distance uncorrected visual acuity and minimize photic phenomena after the implantation of multifocal and extended-depth of focus (EDOF) intraocular lenses (IOLs). This review examines the role of femtosecond laser-assisted cataract surgery (FLACS) in postoperative minimization of astigmatism and optimization of outcomes with multifocal and EDOF lenses.

RECENT FINDINGS

By incorporating intraoperative and preoperative imaging, femtosecond platforms such as those that utilize iris or conjunctival vessel registration, can enable a precision of corneal incisions and toric IOL markings that enable the lowest possible postoperative levels of astigmatism. Current studies suggest that with increasing IOL complexity, that is, trifocal versus bifocal, image degradation with even low levels of postoperative astigmatism are increased. To this end, current data support the utility of femtosecond laser arcuate incisions to enable the achievement of 0.5 D or less postoperative astigmatism for best outcomes with multifocal lenses.

SUMMARY

The synergistic combination of multifocal/EDOF IOLs with FLACS is an extremely promising route in achieving postoperative spectacle independence for patients. The marriage of the precision of FLACS with the increasing complexity of multifocal/EDOF IOLs will fuel nomogram adjustment and systematic improvements, such as the Wörtz-Gupta formula. Such strategies provide an unprecedented precision to cataract surgery that makes FOCUSED (Femtosecond Optimized Continuous Uncorrected Sight with EDOF and Diffractive Multifocal IOLs) a reality.

Sources of error in clinical measurement of the amplitude of accommodation

Measurement of the amplitude of accommodation is established as a procedure in a routine optometric eye examination. However, clinical methods of measurement of this basic optical function have several sources of error. They are numerous and diverse, and include depth of focus, reaction time, instrument design, specification of the measurement end-point, specification of the reference point of measurement, measurement conditions, consideration of refractive error, and psychological factors. Several of these sources of inaccuracy are composed of multiple sub-sources, and many of the sub-sources influence the common methods of measurement of amplitude of accommodation. Consideration of these sources of measurement error casts doubt on the reliability of the results of measurement, on the validity of established normative values that have been produced using these methods, and on the value of reports of the results of surgery designed to restore accommodation. Clinicians can reduce the effects of some of the sources of error by modifying techniques of measurement with existing methods, but a new method may further improve accuracy.

Intraocular lens correction of presbyopia

The continued development of intraocular lens (IOL) technology has led to a dramatic improvement in refractive outcomes. New and innovative ways of achieving the desired postoperative refractive goals continue to be developed. This article aims to review the currently available IOL modalities for correction of presbyopia at the time of cataract surgery, including reference to high-quality comparative studies, where available, and discussion of strengths as well as limitations of the currently available IOL technologies. It has been shown that multifocal compared to monofocal IOL was associated with higher rates of spectacle independence, but higher rates and severity of symptomatic glare as well as reduced contrast sensitivity. Within multifocal IOLs, diffractive compared to refractive IOLs tended to have better near vision and a lower rate of symptomatic glare. Extended depth-of-focus IOLs compared to diffractive multifocal IOL demonstrated equal or superior intermediate visual acuity, with less than or equal rates of glare. Accommodative IOLs represent a broad range of technologies that continue to develop, and new technologies offering opportunities for postoperative adjustment of refractive outcome are emerging.

Premium intraocular lenses: The past, present and future

Purpose

To present potential benefits as well as limitations of premium intraocular lens (IOL) use, and provide insight in future of premium cataract surgery.

Methods

Bibliographic research was performed in PubMed/Medline database, and the most recently updated papers were evaluated. Keywords used were: premium intraocular lens, multifocal intraocular lens, toric intraocular lens, toric multifocal intraocular lens, accommodative intraocular lens, and the respective brand names.

Results

Multifocal IOLs provide uncorrected distance visual acuity (UDVA) of 0.03 logMAR in 82.3%–95.7% of patients and overall spectacle independence in 81%–85% of patients. Toric IOLs provide UDVA of 0.3 logMAR in 70%–95% of patients, residual astigmatism of 1 D or less is noted in 67%–88% of patients, and spectacle independence is reported in 60%–85% of patients. Toric multifocal IOLs provide UDVA of 0.3 logMAR in 92%–97% of patients, and spectacle independence is reported in 79%–90% of patients. Accommodative IOLs represent intensively developing field in ophthalmology, and the results are still variable depending on the IOL model.

Conclusions

Premium IOL technology and advanced surgical techniques have significantly improved postoperative visual outcomes. Future developments will potentiate development of new premium IOL designs that will provide spectacle independence and excellent visual outcomes after cataract surgery.

Optical aberrations, accommodation, and visual acuity with a bioanalogic continuous focus intraocular lens after cataract surgery

Purpose

To evaluate the visual outcomes, pseudoaccommodation, and wavefront aberrometry after implantation of Wichterle IOL-Continuous Focus (WIOL-CF^®, Gelmed International, Kamenne Zehrovice, Czech Republic) by i-Trace aberrometry.

Methods

In this retrospective interventional case series study, after cataract surgery with implantation of accommodative WIOL-CF^®, the patients were evaluated with i-Trace aberrometer for measurement of modulation transfer function (MTF), point spread function (PSF), total aberrations, higher order aberrations (HOAs) at far and near and pseudoaccommodation. The pre and postoperative visual acuity at near and distance were also measured.

Results

Forty eyes of 20 patients (aged 40-77 years) were enrolled in this study with mean follow-up time of up 13.10 ± 5.52 months. The mean logMAR corrected distance visual acuity (CDVA) improved from 0.20 ± 0.14 preoperatively to 0.10 ± 0.09 at the last follow-up after surgery (P = 0.002). The results were 60% J1, 70% J2, 85% J3, 90% J4, 95% J5 and 100% for J6. The mean pseudoaccommodation, range of accommodation volume, and average of peak accommodation were -2.52 ± 1.56 diopters (D), 1.50 to 5.25 D and -3.25 ± 1.25 D, respectively. The mean MTF at 5 cycles per degree at far was 0.200 ± 0.10 and for near was 0.207 ± 0.10. PSF at far and near was 0.0002 and 0.001, respectively. The mean root mean square (RMS) value of HOAs; total, coma spherical aberration, trefoil, and secondary astigmatism were 1.08 ± 0.48 μm, 0.89 ± 0.45 μm, -0.33 ± 0.23 μm, 0.25 ± 0.17 μm, and 0.15 ± 0.13 μm for far and 0.88 ± 0.49 μm, 0.73 ± 0.46 μm, -0.25 ± 0.22 μm, 0.19 ± 0.16 μm and 0.11 ± 0.10 μm for near, respectively. There was a decrease in HOAs at near relative to far (P < 0.05).

Conclusion

WIOL-CF^® seems to be an acceptable accommodative intraocular lens (IOL) in terms of uncorrected near and distant visual outcomes, MTF and HOA.

Accommodative intraocular lenses: where are we and where we are going

Presbyopia still remains the last frontier of refractive surgery. Its surgical management is under constant evolution due to the limitations that exist today with respect to its management, which is probably in relation with the multifactorial basis in which presbyopia is clinically developed in the human. Until currently, virtually all surgical techniques that have been proposed for its correction are based on the induction of pseudoaccommodation in the presbyopic eye, including multifocality. However, the real restoration of accommodation is more complex, and it has been tried by the use of different, so called, “accommodative” pseudophakic intraocular lenses (AIOL). Overall, the reported results with these lenses by independent authors have been modest in relation with the restoration of the accommodative power of the eye and these modest benefits are usually lost with time due to the long term changes in the capsular bag. This fact made these lenses to be almost abandoned in the last few years, but there are currently other AIOL models being used with innovative mechanisms of action and different anatomical support outside the capsular bag that offer encouraging preliminary results that could bring a new potential of application to these types of lenses.

In this article, we will update the modern refractive surgeon about the fundamentals and provide updated information about the outcomes of AIOLs by reviewing the concept of accommodation, the different attempts that have been accomplished in the past, their demonstrated published results in human clinical trials, and the future alternatives that may arrive in the near future.

Achromatic doublet intraocular lens for full aberration correction

A doublet intraocular lens optimized for both chromatic and monochromatic aberration correction in pseudophakic eyes is presented. Ray-tracing techniques were applied to design the lens in white light within a chromatic eye model. Combinations of two materials, already commonly used in intraocular lenses, as acrylic and silicone, were used. Iterative optimization algorithms were employed to correct for longitudinal chromatic aberration, spherical aberration and off-axis aberrations within 10 degrees of visual field. The performance of this lens was compared with a standard single-material aspheric intraocular lens. Near full aberration correction was achieved with the doublet intraocular lens. The modulation transfer function and Strehl ratio were superior for the doublet lens. Through-focus calculations were also conducted showing better optical quality for the doublet. Real higher-order aberrations from normal eyes were incorporated in the model to evaluate the effect on the doublet intraocular lens performance. Results showed that the doublet lens preserved its benefits under realistic conditions. This doublet intraocular lens should provide patients with a better quality of vision after it is further developed in terms of manufacturing and surgical limitations.

Reading charts in ophthalmology

A new generation of logarithmic reading charts has sparked interest in standardized reading performance analyses. Such reading charts have been developed according to the standards of the International Council of Ophthalmology. The print size progression in these calibrated charts is in accordance with the mathematical background of EN ISO 8596. These reading charts are: the Bailey–Lovie Word Reading Chart, the Colenbrander English Continuous Text Near Vision Cards, the Oculus Reading Probe II, the MNREAD Charts, the SKread Charts, and the RADNER Reading Charts. The test items used for these reading charts differ among the charts and are standardized to various extents. The Bailey–Lovie Charts, MNREAD Charts, SKread Charts, and RADNER Charts are also meant to measure reading speed and allow determination of further reading parameters such as reading acuity, reading speed based on reading acuity, critical print size, reading score, and logMAR/logRAD ratio. Such calibrated reading charts have already provided valuable insights into the reading performance of patients in many research studies. They are available in many languages and thus facilitate international communication about near visual performance. In the present review article, the backgrounds of these modern reading charts are presented, and their different levels of test-item standardization are discussed. Clinical research studies are mentioned, and a discussion about the immoderately high number of reading acuity notations is included. Using the logReading Acuity Determination ([logRAD] = reading acuity equivalent of logMAR) measure for research purposes would give reading acuity its own identity as a standardized reading parameter in ophthalmology.

Near vision examination in presbyopia patients: Do we need good homologated near vision charts?

Presbyopia correction is mainly concerned with the goal of regaining an uncorrected reading performance. Since historic reading charts do not provide a unique standard that is applicable for the analysis of clinical and scientific reading performance, new standardized reading charts have been developed, in order to provide reading performance analyses analogous to modern single-optotype distance acuity measurements: the Bailey-Lovie Word Reading Chart, the Colenbrander English Continuous Text Near Vision Cards, the MNREAD Charts, and the RADNER Reading Charts. The last three are also meant to measure reading speed, thus allowing detailed analysis of the reading capabilities of the patient’s functional vision. Furthermore, these reading charts can be declared homologated, based on the standards that were published for reading charts by the Visual Function Committee of the International Council of Ophthalmology (ICO) in 1988. Many research studies have shown that by analyzing the reading performance with homologated reading charts, valuable insight into the reading performance of patients suffering from various diseases can be obtained. These reading charts have also been successfully used in presbyopia research. It therefore seems evident that homologated, standardized reading charts facilitate not only research concerning functional vision in many fields of ophthalmology but also international communication about near visual performance. Homologated reading charts are available in almost all languages and have become a valuable tool in analyzing reading performance. We argue in this review that homologated reading charts are clearly a necessity for presbyopia research.

A review of the surgical options for the correction of presbyopia

Presbyopia is an age-related eye condition where one of the signs is the reduction in the amplitude of accommodation, resulting in the loss of ability to change the eye's focus from far to near. It is the most common age-related ailments affecting everyone around their mid-40s. Methods for the correction of presbyopia include contact lens and spectacle options but the surgical correction of presbyopia still remains a significant challenge for refractive surgeons. Surgical strategies for dealing with presbyopia may be extraocular (corneal or scleral) or intraocular (removal and replacement of the crystalline lens or some type of treatment on the crystalline lens itself). There are however a number of limitations and considerations that have limited the widespread acceptance of surgical correction of presbyopia. Each surgical strategy presents its own unique set of advantages and disadvantages. For example, lens removal and replacement with an intraocular lens may not be preferable in a young patient with presbyopia without a refractive error. Similarly treatment on the crystalline lens may not be a suitable choice for a patient with early signs of cataract. This article is a review of the options available and those that are in development stages and are likely to be available in the near future for the surgical correction of presbyopia.

Axial movement of the dual-optic accommodating intraocular lens for the correction of the presbyopia: optical performance and clinical outcomes

Presbyopia occurs in the aging eye due to changes in the ciliary muscle, zonular fibers, crystalline lens, and an increased lens sclerosis. As a consequence, the capacity of accommodation decreases, which hampers to focus near objects. With the aim of restoring near vision, different devices that produce multiple focuses have been developed and introduced. However, these devices are still unable to restore accommodation. In order to achieve that goal, dual-optic accommodating Intraocular Lenses have been designed, whose anterior optic displaces axially to increase ocular power, and focus near objects. Although dual-optic accommodating IOLs are relatively new, their outcomes are promising, as they provide large amplitudes of accommodation and a greater IOL displacement than single-optic accommodating IOLs. The outcomes show comfortable near vision, higher patients' satisfaction rates, and minimal postoperative complications like Posterior Capsular Opacification and Anterior Capsular Opacification, due to their design and material.