Visual outcomes 24 months after LaserACE

BCLA CLEAR presbyopia: Management with scleral techniques, lens softening, pharmaceutical and nutritional therapies

The aging eye undergoes the same progressive crosslinking which occurs throughout the body, resulting in increased rigidity of ocular connective tissues including the lens and the sclera which impact ocular functions. This offers the potential for a scleral treatment that is based on restoring normal biomechanical movements. Laser Scleral Microporation is a laser therapy that evaporates fractional areas of crosslinked tissues in the sclera, reducing ocular rigidity over critical anatomical zones of the accommodation apparatus, restoring the natural dynamic range of focus of the eye. Although controversial and challenged, an alternative theory for presbyopia is Schachar's theory that suggests a reduction in the space between the ciliary processes and the crystalline lens. Widening of this space with expansion bands has been shown to aid near vision in people with presbyopia, a technique that has been used in the past but seems to be obsolete now. The use of drugs has been used in the treatment of presbyopia, either to cause pupil miosis to increase depth of focus, or an alteration in refractive error (to induce myopia in one eye to create monovision). Drugs and laser ablation of the crystalline lens have been used with the aim of softening the hardened lens. Poor nutrition and excess exposure to ultraviolet light have been implicated in the onset of presbyopia. Dietary nutritional supplements, lifestyle changes have also been shown to improve accommodation and the question arises whether these could be harnessed in a treatment for presbyopia as well.

Correction of presbyopia

Presbyopia, a progressive visual difficulty caused by weakened physiological regulation, is one of the main causes of visual impairment in people over 40 years old. Currently, the main methods of correction of presbyopia include optical correction, surgical correction, and drug treatment, which can improve the visual nearness disorder to some extent. Optical correction is the most common way with advantages of safety, which can adjust the lens parameters at any time, while cause kinds of inconvenience in life by wearing and taking off glasses frequently. Surgical intervention, including corneal surgery, lens surgery and scleral surgery, with certain advantages and disadvantages in each operation style. New pharmaceutical agents are expected to be a new and effective method for the treatment of presbyopia, but it lacks multicenter randomized controlled trials and evidence-based medicine evidence to evaluate the safety and effectiveness.

Future Trends in Presbyopia Correction

Presbyopia affects 1.8 billion people worldwide. This reduction in distance corrected near visual acuity impacts quality of life, which prompts patients to seek treatment. Presbyopia is an early manifestation of the "crystalline lens optical dysfunction through aging," or dysfunctional lens syndrome, and appropriate management of presbyopia is dependent on coexisting factors such as increased higher order aberrations, reduced contrast sensitivity, light scatter, and lenticular opacification. This review of published literature (PubMed and MEDLINE) is presented in narrative format and discusses medical and surgical treatments available to patients who experience presbyopia, while highlighting future therapies. Numerous strategies exist for the management of presbyopia. These strategies include pharmacological therapy, glasses and contact lenses, corneal, scleral, and lenticular procedures. This article discusses the role of several new and existing presbyopia treatments, as well as which patients are candidates for these novel therapies. Although no single treatment is ideal for all patients with presbyopia, new medical and surgical strategies increase the number of options available when addressing different stages of presbyopia and dysfunctional lens syndrome. [J Refract Surg. 2021;37(6 Suppl):S28-S34.].

A preliminary study on the visual outcomes after LaserACE for presbyopia

Background

To investigate the visual outcomes over 1 year after laser anterior ciliary excision (LaserACE) procedure for presbyopic subjects.

Methods

A prospective, non-randomized, non-comparative study. Eight emmetropic eyes of four patients with presbyopia were included in this study. All eyes were treated with the LaserACE procedure using the VisioLite erbium-YAG laser (Ace Vision Group, USA). Subjects were assessed preoperatively and at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year postoperatively. Outcome measures included questionnaires, visual acuity, manifest refraction, pupil size, keratometry, reading prescription, and intraocular pressure.

Results

Binocular distance corrected intermediate visual acuity (DCIVA) had improved from 0.33±0.12 logMAR to 0.12±0.12 logMAR after 6 months (P<0.05) and 0.13±0.12 logMAR after 12 months postoperatively (P<0.01). Binocular distance corrected near visual acuity (DCNVA) improved from 0.41±0.10 logMAR to 0.24±0.12 logMAR after 6 months (P<0.05) and 0.26±0.09 log MAR after 12 months postoperatively (P<0.05). An average decrease of 0.91±0.28 D in the reading prescription at a 40 cm reading distance was observed and remained stable over 12 months (P<0.05). There were no significant differences in manifest refraction, uncorrected distance visual acuity (UDVA), corneal curvature, high order aberrations, pupil size compared with preoperative and 6 months as well as 12 months postoperative visits (P>0.05).

Conclusions

The LaserACE procedure is shown to be safe and efficient for presbyopia correction without influencing distance vision or visual quality. However, its mechanism and long-term effects need further validation.

Tissue Responses and Wound Healing following Laser Scleral Microporation for Presbyopia Therapy

Purpose

To investigate the postoperative inflammatory and wound-healing responses after laser scleral microporation for presbyopia.

Methods

Thirty porcine eyes were used for the optimization of laser intensities first. Six monkeys (12 eyes) received scleral microporation with an erbium yttrium aluminum garnet (Er:YAG) laser, and half of the eyes received concurrent subconjunctival collagen gel to modulate wound-healing response. The intraocular pressure (IOP) and the laser ablation depth were evaluated. The animals were euthanized at 1, 6, and 9 months postoperatively. The limbal areas and scleras were harvested for histologic analysis and immunofluorescence of markers for inflammation (CD11b and CD45), wound healing (CD90, tenascin-C, fibronectin, and HSP47), wound contraction (α-smooth muscle actin [α-SMA]), vascular response (CD31), nerve injury (GAP43), and limbal stem cells (P63 and telomerase).

Results

In the nonhuman primate study, there was a significant reduction in IOP after the procedure. Overall, the ablation depth was 76.6% to 81.2% at 1 month and slightly decreased to 71.5% to 72.7% at 9 months. Coagulative necrosis around the micropores, as well as expression of CD11b, CD45, tenascin, fibronectin, HSP47, and GAP43, was distinct at 1 month but subsided with time. Collagen gel treatment significantly suppressed the upregulation of CD11b, CD45, fibronectin, and tenascin-C. The expression of CD90, α-SMA, and CD31 was minimal in all eyes.

Conclusions

The study demonstrated the course of inflammatory and wound-healing responses following laser scleral microporation. The tissue responses were small and self-limited, resolved with time, and were suppressed by concurrent collagen treatment. It provides a useful understanding of this new procedure.

Translational Relevance

The results would be helpful in the laser parameter modification to improve the long-term treatment stability.

Patient-reported outcome measures in presbyopia: a literature review

Presbyopia is the age-related loss of near-distance focusing ability. The aim of this study was to identify patient-reported outcome measures (PROMs) used in clinical trials and quality-of-life studies conducted in individuals with presbyopia and to assess their suitability for use in individuals with phakic presbyopia. Literature searches were performed in Medline and Embase up until October 2017. Specific search terms were used to identify presbyopia studies that included a PROM. All clinical trials with PROM-supported endpoints in presbyopia were identified on ClinicalTrials.gov. Further searches were conducted to retrieve articles documenting the development and psychometric evaluation of the PROMs identified. A total of 703 records were identified; 120 were selected for full-text review. Twenty-one clinical trials employed PROMs to support a primary or secondary endpoint. In total, 13 PROMs were identified; a further 23 publications pertaining to the development and validation of these measures were retrieved. Most PROMs were developed prior to release of the Food and Drug Administration (FDA) 2009 patient-reported outcome guidance and did not satisfy regulatory standards. The Near Activity Visual Questionnaire (NAVQ) was identified as the most appropriate for assessing near-vision functioning in presbyopia. While the NAVQ was developed in line with the FDA guidance, the items do not reflect changes in technology that have occurred since the questionnaire was developed in 2008 (eg, the increase in smartphone use), and the measure was not validated in a purely phakic presbyopia sample. Further research is ongoing to refine the NAVQ to support trial endpoints related to changes in near-vision functioning associated with phakic presbyopia.

Scleral structure and biomechanics

As the eye's main load-bearing connective tissue, the sclera is centrally important to vision. In addition to cooperatively maintaining refractive status with the cornea, the sclera must also provide stable mechanical support to vulnerable internal ocular structures such as the retina and optic nerve head. Moreover, it must achieve this under complex, dynamic loading conditions imposed by eye movements and fluid pressures. Recent years have seen significant advances in our knowledge of scleral biomechanics, its modulation with ageing and disease, and their relationship to the hierarchical structure of the collagen-rich scleral extracellular matrix (ECM) and its resident cells. This review focuses on notable recent structural and biomechanical studies, setting their findings in the context of the wider scleral literature. It reviews recent progress in the development of scattering and bioimaging methods to resolve scleral ECM structure at multiple scales. In vivo and ex vivo experimental methods to characterise scleral biomechanics are explored, along with computational techniques that combine structural and biomechanical data to simulate ocular behaviour and extract tissue material properties. Studies into alterations of scleral structure and biomechanics in myopia and glaucoma are presented, and their results reconciled with associated findings on changes in the ageing eye. Finally, new developments in scleral surgery and emerging minimally invasive therapies are highlighted that could offer new hope in the fight against escalating scleral-related vision disorder worldwide.

Biomechanical Impact of the Sclera on Corneal Deformation Response to an Air-Puff: A Finite-Element Study

Aim or Purpose: To describe the effect of varying scleral stiffness on the biomechanical deformation response of the cornea under air-puff loading via a finite-element (FE) model. Methods: A two-dimensional axisymmetric stationary FE model of the whole human eye was used to examine the effects varying scleral stiffness and intraocular pressure (IOP) on the maximum apical displacement of the cornea. The model was comprised of the cornea, sclera, vitreous, and surrounding air region. The velocity and pressure profiles of an air-puff from a dynamic Scheimpflug analyzer were replicated in the FE model, and the resultant profile was applied to deform the cornea in a multiphysics study (where the air-puff was first simulated before being applied to the corneal surface). IOP was simulated as a uniform pressure on the globe interior. The simulation results were compared to data from ex vivo scleral stiffening experiments with human donor globes. Results: The FE model predicted decreased maximum apical displacement with increased IOP and increased ratio of scleral-to-corneal Young's moduli. These predictions were in good agreement (within one standard deviation) with findings from ex vivo scleral stiffening experiments using human donor eyes. These findings demonstrate the importance of scleral material properties on the biomechanical deformation response of the cornea in air-puff induced deformation. Conclusion: The results of an air-puff induced deformation are often considered to be solely due to IOP and corneal properties. The current study showed that the stiffer the sclera, the greater will be the limitation on corneal deformation, separately from IOP. This may have important clinical implications to interpreting the response of the cornea under air-puff loading in pathologic conditions.

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.

Scleral surgery for the treatment of presbyopia: where are we today?

Presbyopia corrections traditionally have been approached with attempts to exchange power, either at the cornea or the lens planes, inducing multifocality, or altering asphericity to impact the optical system. Treatments that affect the visual axis, such as spectacle and contact lens correction, refractive surgeries, corneal onlays and inlays, and intraocular lenses are typically unable to restore true accommodation to the presbyopic eye. Their aim is instead to enhance 'pseudoaccommodation' by facilitating an extended depth-of-focus for which vision is sufficient. There is a true lack of technology that approaches presbyopia from a treatment based or therapy based solution, rather than a 'vision correction' solution that compromises other components of the optical system. Scleral surgical procedures seek to restore true accommodation combined with pseudoaccommodation and have several advantages over other more invasive options to treat presbyopia. While the theoretical justification of scleral surgical procedures remains controversial, there has nevertheless been increasing interest and evidence to support scleral surgical and therapeutic approaches to treat presbyopia. Enormous progress in scleral surgery techniques and understanding of the mechanisms of action have been achieved since the 1970s, and this remains an active area of research. In this article, we discuss the historic scleral surgical procedures, the two scleral procedures currently available, as well as an outlook of the future for the scleral surgical space for treating presbyopia.

Correction of presbyopia: An integrated update for the practical surgeon

Presbyopia results from loss or insufficiency of the eye's accommodative ability, and clinically manifests as the inability to focus near objects on the retina. It is one of the most common causes of visual impairment worldwide especially in adults of productive or working age. Various means of compensating for the loss of accommodative ability have been devised from optical tools such as spectacles and contact lenses, to topical medications and to surgical procedures. A comprehensive search on journal articles about topical and surgical correction of presbyopia was undertaken. The various techniques for presbyopia correction, as enumerated in these articles, are discussed in this paper with the addition of our personal experience and perspective on the future of these techniques.