Computer-animated model of accommodation and presbyopia

The potential influence of the ligament of Wieger on the crystalline lens shape

This research uses mathematical modelling to evaluate the influence of the ligament of Wieger on the crystalline lens shape at rest, and during accommodation. An axisymmetric model of the anterior segment, including the ligament of Wieger, was created using the finite element method. Different conditions including variations of stiffness and positions of the ligament, with and without the ligament, were tested to see how they affected lens curvature and optical power. Adding the ligament of Wieger to the simulation had a noticeable impact on the optical power of the lens, particularly on the posterior surface power and total power. Ligament stiffness and width significant influenced the accommodative range of the eye by - 0.95D and - 2.39D for ligaments with the same and 3× the stiffness of the capsular bag, respectively. Ligament width and inner diameter had negligible effects on lens thickness but did have significant effects on posterior surface power and accommodation. In this simulation, we found that the ligament of Wieger can significantly affect the lens shape, both at rest and during accommodation, and may need to be considered in lens models.

Non-Miotic Improvement in Binocular Near Vision with a Topical Compound Formula for Presbyopia Correction

INTRODUCTION

The aim of this case series was to examine the association between unaided binocular visual acuity for near vision and pupil change after the instillation of a special topical formulation for presbyopia treatment.

METHODS

This was a case series consisting of consecutive participants with presbyopia aged 40-70 years who were tested for visual acuity and pupil diameter before and 2 h after instillation of a formulation of pilocarpine and phenylephrine drops (FOV Tears) for presbyopia. Participants underwent subjective refraction, photopic and scotopic pupil diameter measurement and unaided monocular and binocular visual acuity testing by logMAR for distance and near vision both pre- and post-instillation of eye drops.

RESULTS

The study enrolled 363 subjects (n = 176 women, 48%) with a mean (± standard deviation) age of 50.4 ± 5.8 years. Mean spherical equivalent (SE) changed significantly (- 0.17 Diopters) after instillation of the FOV Tears formulation (p < 0.001). Post-instillation of eye drops, the scotopic pupil diameter decreased by 0.97 ± 0.98 mm, and the near visual acuity by logMAR improved significantly by nearly two lines (p < 0.01). In the linear regression analyses, age (p < 0.001) and SE pre-drop instillation (p < 0.001) were associated with unaided binocular visual acuity. The changes in photopic pupil diameter and the scotopic pupil diameter were not associated with unaided binocular visual acuity.

CONCLUSIONS

The use of the pilocarpine and phenylephrine formulation (FOV Tears) improved binocular visual acuity for near vision in presbyopic patients, and the effect was independent of pupil change.

Long Anterior Zonules and Angle Closure Disease

PRCIS

Angle closure disease was present in 59.3% of eyes with long anterior zonules (LAZ). The cause is multifactorial including a thick anteriorly positioned crystalline lens, shorter axial length, and increased lens thickness to axial length factor.

PURPOSE

To study the profile of eyes with LAZ presenting in a glaucoma clinic in a tertiary eye care centre and understand the pathogenesis of angle closure disease in these eyes.

METHODS

This was a retrospective cross-sectional study.All patients with LAZ seen from January 2014 to December 2018 were included. Demographic and clinical characteristics were noted. LAZ eyes (177 eyes of 177 patients) were compared with an equal number of age and sex-matched controls. LAZ was defined as radially oriented zonular fibers (both pigmented and nonpigmented), extending central to the normal zonular termination zone on the anterior lens surface >1 mm beyond their usual insertion of 1.42±0.24 mm from the lens equator onto the mid peripheral zone or central to it, as seen on slit-lamp examination, following pupillary dilation by a single examiner. Glaucoma was defined according to the International Society for Geographical and Epidemiological Ophthalmology classification. The following biometric parameters were compared: anterior chamber depth (ACD), axial length (AXL), lens thickness (LT), lens position (LP=ACD+0.5×LT), relative lens position (RLP=LP/AXL); lens thickness to axial length factor (LAF=(LT/AXL)×10). LAZ eyes without angle closure disease were also compared with controls.

RESULTS

Mean age of patients with LAZ was 64.8±8.1 years. Of these, 63.3% were females. Angle closure disease was present in 59.3% (105/177) patients. Majority of these eyes were primary angle closure suspects (PACS) (53.3%, n=56). Significant differences were found between LAZ eyes and controls for LT (4.8±0.38 mm vs. 4.49±0.40 mm, P<0.0001), ACD (2.68±0.39 mm vs. 3.0±0.32 mm, P<0.0001), AXL (22.37±0.79 mm vs. 22.94±1.1, P<0.0001), LAF (2.14±0.19 vs. 1.96±0.21, P<0.0001), and LP (5.07±0.37 vs. 5.3±0.25, P<0.0001).

CONCLUSIONS

Angle closure was present in more than half the eyes with LAZ. Majority of these eyes were PACS or had primary angle closure. LAZ eyes had a thicker lens, shallow AC, a shorter axial length and an increased LAF as compared with age and sex matched normal controls. The presence of LAZ may be an indicator of increased risk for angle closure.

Presbyopia Treatments by Mechanism of Action: A New Classification System Based on a Review of the Literature

Presbyopia, a loss of accommodative ability associated with aging, is a significant cause of vision impairment globally. At the clinical level, it is a frustrating and difficult issue that negatively impacts patients’ quality of life. Less appreciated is the fact that loss of accommodative ability and its current treatments methods may present safety concerns, for example, increasing the risk of falls. Therefore, a more complete understanding of treatment options with respect to how they relate to the natural ability of the eye is needed to improve decision making and to aid clinicians in individualizing treatment options. This article reviews the options for expanding functional through focus—a term coined to describe the ability of the eye to see at all distances with minimal latency—by how they vary the refractive power over time, across the visual field, between eyes, or across a range of distances.

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Clarifying the Disease State of Presbyopia

Presbyopia is the consequence of the slow and progressive universal decline in the amplitude of accommodation with age, and it will eventually affect everyone. This article discusses the disease state of presbyopia and describes the classifications of its progression. [J Refract Surg. 2021;37(6 Suppl):S8-S11.].

Phacoemulsification in eyes with long anterior zonules

PURPOSE

To study the safety of phacoemulsification in eyes with long anterior zonules (LAZs).

SETTING

Institute.

DESIGN

Retrospective interventional case series.

METHODS

All patients with clinically proven LAZs who had undergone phacoemulsification by a single surgeon from January 2014 to December 2018 were included. All cases of LAZs with cataract extraction by procedures other than phacoemulsification or combined with any other ocular surgery were excluded. Sixty-five eyes of 52 patients were analyzed. Phacoemulsification with capsulorhexis that involves sacrificing the LAZs was performed. The primary outcome measures were the incidence of capsulorhexis extension or the need to rescue intraoperatively and the rate of intraoperative complications. Secondary outcomes assessed were the percentage of eyes within ±0.5 diopters (D) and ±1 D of the target refraction.

RESULTS

Sixty-five eyes (52 patients) were analyzed; the mean age of patients was 67.3 ± 7.4 years. The successful completion of an adequately sized capsulorhexis without extension or rescue was seen in 100% of cases. The incidence of intraoperative complications was 1.5% (posterior capsular rupture in 1 eye). The mean postoperative corrected distance visual acuity was 0.05 ± 0.1 (logarithm of the minimum angle of resolution) at a mean of 26.8 ± 7.6 days. The mean spherical equivalent was -0.15 ± 0.7 D. Eyes within ±0.5 D and ±1.00 D of the target refraction were 77% and 94%, respectively.

CONCLUSIONS

Phacoemulsification in eyes with LAZs can be safely performed through an adequately sized capsulorhexis by sacrificing, ie, cutting or breaking, the anteriorly inserted zonules 360 degrees without significant intraoperative complications.

The action of ciliary muscle contraction on accommodation of the lens explored with a 3D model

The eye's accommodative mechanism changes optical power for near vision. In accommodation, ciliary muscle excursion relieves lens tension, allowing it to return to its more convex shape. Lens deformation alters its refractive properties, but the mechanics of ciliary muscle actions are difficult to intuit due to the complex architecture of the tissues involved. The muscle itself comprises three sections of dissimilarly oriented cells. These cells contract, transmitting forces through the zonule fibers and extralenticular structures. This study aims to create a finite element model (FEM) to predict how the action of the ciliary muscle sections leads to lens displacement. The FEM incorporates initialization of the disaccommodated lens state and ciliary muscle contraction, with three muscle sections capable of independent activation, to drive accommodative movement. Model inputs were calibrated to replicate experimentally measured disaccommodated lens and accommodated ciliary muscle shape changes. Additional imaging studies were used to validate model predictions of accommodative lens deformation. Models were analyzed to quantify mechanical actions of ciliary muscle sections in lens deformation and position modulation. Analyses revealed that ciliary muscle sections act synergistically: the circular section contributes most to increasing lens thickness, while longitudinal and radial sections can oppose this action. Conversely, longitudinal and radial sections act to translate the lens anteriorly with opposition from the circular section. This FEM demonstrates the complex interplay of the three sections of ciliary muscle in deforming and translating the lens during accommodation, providing a useful framework for future investigations of accommodative dysfunction that occurs with age in presbyopia.

Surgical correction of presbyopia

Presbyopia is the most common refractive disorder for people older than 40 years. It is characterized by a gradual and progressive decrease in accommodative amplitude. Many surgical procedures for the correction of presbyopia exist, with additional procedures on the horizon. This review describes the prevalent theories of presbyopia and discusses the available surgical options for correction.

FINANCIAL DISCLOSURE

Proprietary or commercial disclosures are listed after the references.

Long-term visual outcomes of laser anterior ciliary excision

Purpose

To determine the long-term visual outcomes of six eyes of 3 patients up to 13 years following the Laser Anterior Ciliary Excision (LaserACE) procedure.

Methods

Three male patients of ages 59, 59, and 60 presented for evaluation at Storm Eye Institute, Medical University of South Carolina at 8, 10, and 13 years after the LaserACE procedure for presbyopia, respectively. All 3 patients had a history of laser vision correction (LVC) prior to LaserACE treatment. Visual performance was evaluated using ray-tracing aberrometry, specifically higher-order aberrations, visual Strehl of the optical transfer function (VSOTF), depth of focus (DoF), and effective range of focus (EROF). VSOTF was computed as a function of defocus using a through-focus curve. Subjective DoF was overlaid on the VSOTF through-focus curve to establish the best image quality metric threshold value for correlation between subjective and objective DoF. EROF was determined by measuring the difference in diopters between the near and distance DoF curves, at 50% of VSOTF.

Results

Distance-corrected visual acuity, distance-corrected intermediate visual acuity, and distance-corrected near visual acuity for all patients remained at 20/20 or better up to 13 years postoperatively. EROF averaged 1.56 ± 0.36 (D) for all eyes.

Conclusions and Importance

LaserACE provided improvement in near vision functionality in these LVC patients with long-term stability. The LaserACE procedure is not on the visual axis, therefore these patients could still receive correction to their hyperopic regression.

Comparison of FDA safety and efficacy data for KAMRA and Raindrop corneal inlays

AIM

To provide a side-by-side analysis of the summary of safety and effectiveness data (SSED) submitted to the FDA for the KAMRA and Raindrop corneal inlays for the correction of presbyopia.

METHODS

SSED reports submitted to the FDA for KAMRA and Raindrop were compared with respect to loss of corrected distance visual acuity (CDVA), adverse event rates, induction of astigmatism, retention of contrast sensitivity, stability of manifest refractive spherical equivalent (MRSE), and achieved monocular uncorrected near visual acuity (UNVA) at 24mo.

RESULTS

Totally 442/508 of KAMRA patients and 344/373 Raindrop patients remained enrolled in the clinical trials at 24mo. The proportion of KAMRA and Raindrop patients who lost ≥2 lines of CDVA at 24mo was 3.4% and 1%, respectively. The adverse event rate was comparable between the devices. No significant inductions of astigmatism were noted. Both technologies induced a transient myopic shift in MRSE followed by a hyperopic shift and subsequent stabilization. Totally 87% of KAMRA and 98% of Raindrop patients attained a monocular UNVA of J5 (20/40) or better at 24mo, 28% of KAMRA and 67% of Raindrop patients attained a monocular UNVA of J1 (20/20) or better at 24mo.

CONCLUSION

Both devices can be considered safe and effective, however, the results of corneal inlay implantation are mixed, and long-term patient satisfaction will likely depend on subjective expectations about the capabilities of the inlays. Variability in surgical technique and postoperative care within and between the two clinical trials diminishes the comparative power of this article.

Visual outcomes 24 months after LaserACE

Background

To evaluate the effects on near and intermediate visual performance after bilateral Laser Anterior Ciliary Excision (LaserACE) procedure.

Methods

LaserACE surgery was performed using the VisioLite 2.94 μm erbium: yttrium–aluminum–garnet (Er:YAG) ophthalmic laser system in 4 oblique quadrants on the sclera over the ciliary muscle in 3 critical zones of physiological importance (over the ciliary muscles and posterior zonules) with the aim to improve natural dynamic accommodative forces. LaserACE was performed on 26 patients (52 eyes). Outcomes were analyzed using visual acuity testing, Randot stereopsis, and the CatQuest 9SF patient survey.

Results

Binocular uncorrected near visual acuity (UNVA) improved from +0.20 ± 0.16 logMAR preoperatively, to +0.12 ± 0.14 logMAR at 24 months postoperatively (p = 0.0014). There was no statistically significant loss in distance corrected near visual acuity (DCNVA). Binocular DCNVA improved from +0.21 ± 0.17 logMAR preoperatively, to +0.11 ± 0.12 logMAR at 24 months postoperatively (p = 0.00026). Stereoacuity improved from 74.8 ± 30.3 s of arc preoperatively, to 58.8 ± 22.9 s of arc at 24 months postoperatively (p = 0.012). There were no complications such as persistent hypotony, cystoid macular edema, or loss of best-corrected visual acuity (BCVA). Patients surveyed indicated reduced difficulty in areas of near vision, and were overall satisfied with the procedure.

Conclusions

Preliminary results of the LaserACE procedure show promising results for restoring visual performance for near and intermediate visual tasks without compromising distance vision and without touching the visual axis. The visual function and visual acuity improvements had clinical significance. Patient satisfaction was high postoperatively and sustained over 24 months.

Trial registration

NCT01491360 (https://clinicaltrials.gov/ct2/show/NCT01491360). Registered 22 November 2011.

Accommodation in human eye models: a comparison between the optical designs of Navarro, Arizona and Liou-Brennan

AIM

To simulate and compare accommodation in accommodative and non-accommodative human eye models.

METHODS

Ray tracing and optical design program was used. Three eye models were designed and studied: the Navarro, the Arizona and the Liou-Brennan. In order to make the Navarro and Liou-Brennan models to accommodate, specific geometric parameters of the models were altered with values that were chosen from the literature. For the Arizona model, its' mathematical functions for accommodation were used for the same accommodative demands. The simulation included four distances of accommodation for each model: at infinity, 3, 1 and 0.5 m.The results were diffraction images of a "letter F" for graphical comparison, spot diagrams on the retinal field and Modulation Transfer Function (MTF) graphs.

RESULTS

Zernike coefficients for the aberrations, Airy disk diameter, root mean square (RMS) error diameter and total axial length of the model were provided from the program. These were compared between them in all distances. The Navarro model had the smallest axial length change as a simple model. The Arizona did not change its axial length because it is designed to be accommodative. The Liou-Brennan model had different results concerning the aberrations because of the decentration of the pupil. The MTF graphs showed small differences between the models because of the differences in their designs.

CONCLUSION

All the three models are able to simulate accommodation with the expected results. There is no model that can be assumed as the best choice. Accommodation can be simulated in non-accommodativemodels and in customized ones.

Real-Time Intraoperative Optical Coherence Tomography Imaging Confirms Older Concepts About the Berger Space

BACKGROUND

The presence of a space between the posterior capsule and the anterior vitreous was first reported in 1887, but difficulties inherent in examining this structure made it impossible to visualize this area in vivo until now. Estimation of the size of this space was considered to be impossible.

MATERIALS AND METHODS

We utilized an optical coherence tomography (OCT) system attached to the Zeiss Opmi Lumera 700/Rescan microscope (Zeiss Ltd., Jena, Germany) to provide real-time images of the Berger space, the anterior hyaloid and the ligament of Wieger.

RESULTS

Imaging in 3 patients provided beautiful, real-time OCT images of the Berger space and of the ligament of Wieger. In one highly myopic eye, there was even evidence of anterior vitreous detachment.

CONCLUSION

Previously unseen transparent structures of the eye can now be imaged intraoperatively using real-time OCT. This new technology seems very promising in achieving a better understanding of the anterior vitreous interface, more specifically of the anterior hyaloid and its posterior capsule attachment by the ligament of Wieger. Changes in the anterior hyaloid and its capsular attachment may contribute to a better understanding of the posterior segment complications after cataract surgery.