Presbyopia Correction: Advancements in Corneal-Based Approaches

Presbyopia remains one of the most complex and universally experienced visual challenges – an age-related decline in accommodation affecting nearly every individual over the age of 45. It arises due to the loss of elasticity and accommodative power of the crystalline lens. While the ideal solution would be to restore natural lens function, current technologies are still limited to experimental models and preclinical settings.

Currently, clinical presbyopia correction remains grounded in three main strategies: monovision, multifocality, and extended depth of focus (EDOF). Each can be achieved either at the corneal or lenticular level. However, conventional monovision can impair stereoacuity, while multifocal solutions often come with compromises in contrast sensitivity and night vision quality.

Recent advances in corneal-based presbyopia correction – particularly laser-induced aspheric profiles and biologic inlays – are providing more precise options for patients who seek functional near vision with minimal compromise to distance clarity and depth perception. These techniques employ controlled induction of spherical aberration in combination with mini-monovision, enhancing near vision while preserving quality of distance vision. This article explores some of the most notable recent innovations.

PRESBYOND Laser Blended Vision

PRESBYOND Laser Blended Vision (Carl Zeiss Meditec) offers a sophisticated corneal solution based on micro-anisometropia combined with non-linear aspheric laser ablation. This profile expands the depth of field in each eye by inducing spherical aberration – resulting in a continuous visual range from distance to near.

Both myopic and hyperopic corrections benefit: myopic treatments typically produce positive spherical aberration, while hyperopic ones induce negative values. The CRS-Master system or Refractive Workplace (Carl Zeiss Meditec AG) is used to generate the aspheric ablation profile using the spherical aberration data obtained by an aberrometer like Osiris (Costruzioni Strumenti Oftalmici). The patient’s overall depth of focus is expanded by the introduction of both positive and negative spherical aberration, up to a maximum value of ±0.5 to 0.6 µm in a symmetrical trend (1). The SA combined with micro-monovision widens the overall depth of focus – often achieving up to 2.8 D of functional range across the two eyes.

Recent clinical data reinforce the efficacy and safety of PRESBYOND. A 2022 multicentre study of 139 patients (1) showed:

• Binocular UDVA better than 20/20 in over 90% of cases

• Mean binocular uncorrected near visual acuity (UNVA) of 0.1 logMAR and 0.15 logMAR for hyperopic and myopic eyes respectively 

• Stable stereoacuity in 85% of patients

• High patient satisfaction, with most reporting scores above 90 on subjective vision quality assessments

• Enhancement rates remain low (~5–8%) with high refractive predictability (±0.50 D in >80% of eyes)

The success of PRESBYOND hinges on precise induction of spherical aberration. The procedure requires rigorous centration, accurate dominance testing, a consistent refraction protocol and whole eye aberrometry. For early presbyopes hesitant about lens surgery, PRESBYOND delivers effective, reversible presbyopia correction with excellent patient satisfaction.

PresbyMAX: Biaspheric Corneal Multifocality with Flexibility

PresbyMAX (SCHWIND eye-tech-solutions) is a bi-aspheric corneal ablation technique designed to induce multifocality by reshaping the cornea into a central hyper-positive zone for near, inducing negative spherical aberration, surrounded by a periphery optimised for distance vision. The multifocal pattern relies on wavefront-optimised technology that preserves quality of vision while enhancing depth of focus.

One of its key strengths is customization, with three core variants:

• PresbyMAX Symmetric: identical multifocal ablation in both eyes

• PresbyMAX µ-Monovision: near vision in the non-dominant eye, distance in the dominant eye, with slight anisometropia

• PresbyMAX Hybrid: a blended approach using asymmetric ablation tailored to refractive profile and dominance

In a study by Uthoff et al. (2) involving hyperopic, myopic, and emmetropic presbyopes:

• 83% achieved a UDVA of 0.1 logMAR or better

• 90% of emmetropic and 80% of hyperopic and myopic patients reached UNVA of 0.3 logMAR or better

• Some BCDVA loss was observed, especially in hyperopic eyes (10–20%), but most patients remained functionally independent from spectacles

A more recent study by Chan et al. utilising the PresbyMAX monocular approach (3) did not report any patients with a 2-line loss of BCVA. PresbyMAX is ideal for those who tolerate mild multifocality well and benefit from platform flexibility (e.g. availability on SmartSurfACE for thin corneas or surface ablation).

Custom-Q

Custom-Q ablation, as described by Damien Gatinel and others, offers a highly physiologic corneal solution by preserving and modifying the Q-value of the cornea to simulate multifocality via extended depth of focus (EDOF). The principles have been used to develop the READ correction solution recently implemented in the Alcon Wavelight EX500 laser (Alcon Laboratories, Inc.) processing software. Rather than inducing significant anisometropia or abrupt multifocal profiles, Custom-Q enhances prolaticity (negative Q) to introduce controlled negative spherical aberration in the non-dominant eye (4, 5). 

The optical principle is simple yet powerful:

• There is a difference between the induced myopic error within the paraxial pupil zone and the low myopic to emmetropic paracentral zone.

• Reducing the myopic refractive error toward the pupil edge aims to provide the eye with better-uncorrected distance visual acuity. 

• “This gradient of defocus from the centre to the edge of the pupil is reflected in the induction of negative spherical aberration”. 4

In practical terms:

• Surgeons typically correct the non-dominant eye to –0.75 D to –1.50 D

• The Q-value is modified toward –0.6 to –0.7, inducing about –0.4 μm of negative spherical aberration (6 mm pupil)

• Pupil size and dynamics are critical—this technique works on the principle that there is pupillary miosis during accommodation

Custom-Q offers a low-aberration, low-disruption option – especially valuable in early hyperopic presbyopes, in combination with monovision. Courtin et al (5) reported, 

• Near vision: At six months, 83% of patients achieved Jaeger 3 (Parinaud 4) or better binocular uncorrected near visual acuity (UNVA).

• Distance vision: 91% achieved 20/20 or better binocular uncorrected distance visual acuity (UDVA), with a mean binocular UDVA of 0.01 ± 0.04 logMAR.
  

Supracor

SUPRACOR (Technolas Perfect Vision) employs an aberration-optimized laser algorithm to reshape the central 3.0 mm of the cornea, creating a hyperpositive zone that adds approximately +2.00 D for near vision. It can be used bilaterally with a mild myopic target of -0.50 D or in a micro-monovision approach with plano in the dominant eye. By minimizing surgically induced aberrations, SUPRACOR aims to enhance near vision while maintaining distance quality. Clinical results show 87%–91% of patients achieve N8 or better uncorrected near visual acuity, though 6%–10% may lose two or more lines of corrected distance visual acuity (CDVA) (6).

Allotex Inlays

Allotex® is a biocompatible, allogenic corneal inlay derived from processed donor corneal stroma. The implant is shaped into a thin (20 µm), dome-shaped lenticule, designed to be inserted under a LASIK flap or within a corneal pocket in the non-dominant eye. Its mode of action is tissue addition, subtly modifying central curvature and inducing a controlled amount of 4th and 6th order aberrations to enhance EDOF.

Clinical evidence shows:

• Improvement from J6 to J2 in UNVA with 88% near spectacle independence at 3 years

• No cases of haze, rejection, or explantation

• Preservation of UDVA in most patients

• A 2.8 D usable depth of focus—comparable to EDOF IOLs (7, 8)

What makes Allotex unique is its tissue-based design offering an additive solution. Unlike synthetic inlays, which have historically been associated with complications like haze or foreign body reaction, Allotex uses a biologic, transparent collagen matrix that integrates naturally into the corneal stroma but is also reversible.

Performing Australia’s first Allotex implantation at IVISION LASER was a milestone, and I have seen first-hand patients experiencing near vision improvement within a day, with distance vision optimising over subsequent months with epithelial remodelling. 

Conclusions: A Layered and Personalised Approach

Presbyopia correction is no longer a binary choice between reading glasses or multifocal IOLs. With modern corneal-based solutions, refractive surgeons now have a toolbox of tailored strategies to address different patient needs, refractive profiles, and lifestyle demands. 

In my practice, corneal-based presbyopia treatments, such as PresbyMAX and Allotex, serve as a valuable option for early presbyopes, 45 to 55 years old – particularly those with some residual accommodation – who are seeking improved near vision without the invasiveness of intraocular surgery. The key shift is in the preservation of distance acuity and stereopsis compared to traditional monovision. 

Laser-based solutions provide the precision and predictability we associate with laser vision correction with high patient satisfaction. The choice of technology is affected by laser platform availability, which influences both patient selection and surgical planning. In this patient group, attention is required towards ocular surface optimization and dry eye management. As with all presbyopia interventions, thorough preoperative counselling remains essential to align outcomes with patient expectations.

These innovations reflect a broader shift in refractive surgery – from singular, one-size-fits-all procedures toward a layered and personalised model of vision correction. It signals a future where presbyopia management is not just corrective, but strategically bespoke.