Virtual Issue Editorial: Presbyopia - grappling with an age-old problem

Pharmacological Treatments for Presbyopia

Accommodation is the change in dioptric power of the eye. It is a dynamic process that allows focusing on an object at all distances. In order to focus sharply, three physiological responses, known as the triad of accommodation, are produced by a change in pupil size, a change in shape and position of the lens, and ocular convergence. This is modulated by the autonomic nervous system, mainly the parasympathetic nervous system. Presbyopia is a refractive condition that occurs with aging, usually manifesting around 40-50 years of age, and is a result of the loss of accommodation in the eye, causing loss of visual performance when focusing on objects placed at different distances, starting with near vision. Glasses, contact lenses, surgical approaches and now pharmacological treatments are accepted methods of treating presbyopia. Pharmacological treatment is a promising new noninvasive option for treating presbyopia. Currently there are three pharmacological approaches to the treatment of presbyopia. The first one aims to produce miosis and, from a pinhole effect, increase depth of focus, and therefore improve uncorrected near visual acuity (UNVA). The second one addresses rehabilitating accommodation in a binocular way, allowing good vision at all distances. Finally, the third strategy uses lipoic acid to restore the lost elasticity of the lens. All of these pharmacological treatments are topical non-invasive eyedrops, with no serious adverse effects having been reported with any of the strategies, and require the right patient selection process to fulfill expectations and needs. The aim of this article is to provide an update on recent advances in this field.

Complications of Small Aperture Intracorneal Inlays: A Literature Review

Presbyopia can be defined as the refractive state of the eye in which, due to a physiological decrease in the ability to accommodate, it is not possible to sustain vision without fatigue in a prolonged manner, along with difficulty focusing near vision. It is estimated that its prevalence in 2030 will be approximately 2.1 billion people. Corneal inlays are an alternative in the correction of presbyopia. They are implanted beneath a laser-assisted in situ keratomileusis (LASIK) flap or in a pocket in the center of the cornea of the non-dominant eye. The purpose of this review is to provide information about intraoperative and postoperative KAMRA inlay complications in the available scientific literature. A search was conducted on PubMed, Web of Science, and Scopus with the following search strategy: ("KAMRA inlay" OR "KAMRA" OR "corneal inlay pinhole" OR "pinhole effect intracorneal" OR "SAICI" OR "small aperture intracorneal inlay") AND ("complication" OR "explantation" OR "explanted" OR "retired"). The bibliography consulted shows that the insertion of a KAMRA inlay is an effective procedure that improves near vision with a slight decrease in distance vision. However, postoperative complications such as corneal fibrosis, epithelial iron deposits, and stromal haze are described.

Presbyopia Treatment With Eye Drops: An Eight Year Retrospective Study

Purpose

The purpose of this study was to evaluate the safety and efficacy across time, of patients topically treated with Benozzi's method for presbyopia.

Methods

A nonrandomized case series retrospective study was developed, including patients with emmetropia with binocular uncorrected distance visual acuity (UDVA) of 25/20 or better, and with uncorrected near visual acuity (UNVA) at least Jaeger 2 or worse. The study was set in Buenos Aires, Argentina, from January 2011 to June 2018, with at least 1-year follow-up. Patients were treated with pilocarpine and diclofenac preservative-free eye drops (Benozzi Method; US 8.524.758 B2, EP1.938.839 B1), and the main outcome measured was binocular UNVA at different follow-up times. Other parameters, as the UDVA and presence of side effects, were evaluated.

Results

A total of 910 patients were included with a mean age at baseline of 48.67 ± 3.72 years old (range, 40–59 years). The baseline UNVA was 4.74 ± 1.53 and at 8 years of follow-up was decreased to 1.36 ± 0.48 (Jaeger scale). The mean binocular UDVA at baseline was 0.00 ± 0.01 logarithm of the minimum angle of resolution (logMAR) and after 8 years of follow-up was 0.03 ± 0.04 logMAR. All side effects reported (decrease of light perception, headaches, symptoms of ocular surface dryness, and dizziness) were spontaneously resolved in patients who continued with the treatment.

Conclusions

The efficacy of the pharmacological treatment of presbyopia to improve the UNVA without affecting the UDVA is shown. Side effects were well tolerated and resolved before 1 year of treatment.

Translational Relevance

This is a nonsurgical option for patients with emmetropic presbyopia who do not wish to wear glasses, which is a pharmacological treatment with eye drops.

Optimization of the Light Sword Lens for Presbyopia Correction

Purpose

We propose and evaluate the modifications of a light sword lens (LSL) to obtain better performance for distance vision while maintaining good operation for near and intermediate vision.

Methods

The modifications consisted of assigning angular or circular windows for distance vision while rescaling the LSL profile in the remaining area of the element. The objective performance of the redesigned LSLs was verified numerically by the Strehl ratio and experimentally using correlation coefficients and Michelson contrast. Subjective assessments were provided by monocular visual acuity (VA) and contrast sensitivity (CS) through-focus curves for six patients with paralyzed accommodation. The tested object vergence range was [-4.0, 0.0] diopters (D). All experiments were conducted in a custom-made monocular visual simulator.

Results

Computational simulations and objective experiments confirmed the better performance of the modified LSL for the imaging of distant objects. The proposed angular and radial modulations resulted in flat VA and CS through-focus curves, indicating more uniform quality of vision with clearly improved distance vision. The VA provided by the modified LSL profiles showed a maximal improvement of 1.5 lines of acuity with respect to the VA provided by the conventional LSL at distance vision.

Conclusions

Optimized LSLs provide better imaging of distant objects while maintaining a large depth of focus. This results in comparable and acceptable quality for distance, intermediate, and near vision. Therefore, the modified LSLs appear to be promising presbyopia correctors.

Translational Relevance

The new design of LSL reveals an improved performance for all ranges of vision and becomes a promissory element for a real presbyopia correction in clinical applications.

Effect of Optical Defocus on Choroidal Thickness in Healthy Adults With Presbyopia

Purpose

To investigate changes in subfoveal choroidal thickness (SFCT) induced by retinal defocus in presbyopic adults.

Methods

Thirty-seven healthy presbyopic subjects (age 57.74 ± 4.06 years) with low refractive errors (+0.08 ± 1.09 Diopters [D]) viewed a distant target (video movie at 6 m) for 60 minutes on two occasions while SFCT was monitored with optical coherence tomography every 20 minutes. On each occasion, both eyes were optimally corrected for distance: one eye acted as control, while the other (experimental) eye viewed through an additional ophthalmic lens: a +2.00 D lens imposing myopic defocus on one occasion and a -2.00 D lens imposing hyperopic defocus on the other occasion.

Results

Baseline SFCT was not different between experimental and control eyes (226 ± 72 μm vs. 232 ± 75 μm; P = 0.28). Myopic defocus caused a significant (P < 0.001) increase in SFCT in the defocused eye by 20 minutes (and +10 ± 5-μm increase at 60 minutes: P < 0.001), while hyperopic defocus caused a significant decrease in SFCT by 20 minutes (and -10 ± 5-μm decrease at 60 minutes: P < 0.001) with no change in control eyes.

Conclusions

In presbyopic subjects, imposed myopic retinal defocus caused thickening of SFCT, while hyperopic defocus caused thinning of SFCT. This implies that uncorrected presbyopia, which is associated with hyperopic retinal defocus for near objects and which is highly prevalent in the developing world, would likely be associated with choroidal thinning and possibly reduced choroidal blood flow with prolonged periods in a near visual environment.

Presbyopia: Effectiveness of correction strategies

Presbyopia is a global problem affecting over a billion people worldwide. The prevalence of unmanaged presbyopia is as high as 50% of those over 50 years of age in developing world populations, due to a lack of awareness and accessibility to affordable treatment, and is even as high as 34% in developed countries. Definitions of presbyopia are inconsistent and varied, so we propose a redefinition that states "presbyopia occurs when the physiologically normal age-related reduction in the eye's focusing range reaches a point, when optimally corrected for distance vision, that the clarity of vision at near is insufficient to satisfy an individual's requirements". Strategies for correcting presbyopia include separate optical devices located in front of the visual system (reading glasses) or a change in the direction of gaze to view through optical zones of different optical powers (bifocal, trifocal or progressive addition spectacle lenses), monovision (with contact lenses, intraocular lenses, laser refractive surgery and corneal collagen shrinkage), simultaneous images (with contact lenses, intraocular lenses and corneal inlays), pinhole depth of focus expansion (with intraocular lenses, corneal inlays and pharmaceuticals), crystalline lens softening (with lasers or pharmaceuticals) or restored dynamics (with 'accommodating' intraocular lenses, scleral expansion techniques and ciliary muscle electrostimulation); these strategies may be applied differently to the two eyes to optimise the range of clear focus for an individual's task requirements and minimise adverse visual effects. However, none fully overcome presbyopia in all patients. While the restoration of natural accommodation or an equivalent remains elusive, guidance is given on presbyopic correction evaluation techniques.