Surgical compensation of presbyopia with corneal inlays

Abstract

Presbyopia, the physiological change in near vision that develops with ageing, gradually affects individuals older than 40 years and is a growing cause of visual disability due to ageing demographics of the global population. The routine use of computers and ‘smartphones’, combined with the affluence of the ‘baby boomers’ generation has set high standards for near vision correction. Corneal inlays are a relatively new treatment modality that is effective at compensating for presbyopia. The dimensions of these devices vary from 2 to 3.8 mm in diameter and 5 to 32 μm in thickness. They are implanted in the anterior corneal stroma of the non-dominant eye, most commonly, in a femtosecond laser created corneal pocket. They improve near vision by increasing the depth of focus, creating a hyper-prolate region of increased central cornea power or providing a refractive add power. This article reviews the literature on the efficacy and safety of corneal inlays.

Keywords:

• Flexivue microlens
• Icolens
• inlay
• Kamra
• presbyopia
• Raindrop

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organisation or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilised in the production of this manuscript.

Key issues

• Presbyopia, the physiological change in near vision that gradually affects individuals older than 40 years, is a growing cause of visual disability due to ageing of the population, especially in developed countries.

• Corneal inlays are a relatively new treatment option for presbyopia. They have the potential for reversibility and future proofing should the refractive status or requirements change.

• Currently, there are four corneal inlays available; the Kamra Vision^TM (Acufocus Inc., Irvine, CA, USA), the Raindrop^TM (ReVision Optics Inc., Lake Forest, CA, USA), the Presbia Flexivue Microlens^TM (Presbia Cooperatief U.A., Amsterdam, Netherlands), and the Icolens^TM (Neoptics AG, Huenenberg, Switzerland).

• The Kamra inlay uses the principle of small-aperture optics and improves near vision by increasing the depth of focus.

• The Raindrop inlay is a space-occupying inlay that reshapes the central anterior corneal surface, creating a hyper-prolate region of increased power for near focusing.

• The Flexivue Microlens and Icolens are refractive inlays that have a peripheral zone of refractive add power for near vision.

• Inlays are placed in the non-dominant eye of the patient, most commonly, in a femtosecond laser created corneal pocket or flap. The depth of the flap or pocket, usually between 150 and 200 μm, depends on the inlay and its mode of action.

• All inlays successfully improve near and intermediate vision. However, loss of unaided distance vision is common and loss of corrected distance vision can also occur. Binocular vision is usually unaffected and the vast majority of patients are satisfied with the outcome of surgery. Other side effects, such as glare and haloes, may precipitate inlay removal.

• Improvements in implantation techniques and understanding of the optics of these devices may lead to adoption of cornea inlays as a mainstream modality for the surgical correction of presbyopia.