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For ophthalmic surgeons · IOL optical design
Extended depth of focus (EDOF) IOLs: how they work and how they compare with trifocal lenses
Agaaz Ophthalmics, clinical and technical article · 12 October 2026
In brief: an EDOF lens creates a single elongated focus instead of several separate foci, extending the range of sharp vision from distance into the intermediate zone. According to two systematic reviews, distance and intermediate visual acuity are comparable between EDOF and trifocal IOLs; trifocals provide better uncorrected near vision, and no significant differences in halos and glare were found.
What is an EDOF lens
A monofocal IOL focuses light at a single point: the patient sees well at one distance, usually far. Multifocal lenses — bifocal and trifocal — split light between two or three foci. An EDOF lens takes a different approach: instead of separate foci it creates a single elongated focal zone, increasing depth of focus without splitting light into discrete images.
The ANSI Z80.35-2018 standard provides a formal criterion: at an acuity level of 0.2 logMAR, the depth of focus of an EDOF lens must be at least 0.5 D greater than that of a monofocal control lens. The definition of EDOF, the requirements for such lenses and manufacturers' approaches are reviewed in detail by T. A. Morozova in the Annals of the Russian Academy of Medical Sciences (Vestnik RAMN) [1].
How extended depth of focus is achieved
- Diffractive designs — echelette diffractive profiles that stretch the focus; historically the first widely used group of EDOF lenses.
- Refractive designs — control of spherical aberration and wavefront shape across optic zones without a diffractive relief.
- Small aperture — the pinhole principle, blocking peripheral rays.
The common trade-off for extended depth of focus is some loss of image quality when aberrations are increased excessively and, for some designs, photic phenomena. What matters to the surgeon is therefore not the “EDOF” label but the defocus curve and contrast sensitivity data for the specific model.
EDOF or trifocal IOL: what the systematic reviews show
Cochrane review, 2024
Tavassoli et al. included 5 studies (233 participants, 466 eyes) comparing trifocal lenses with EDOF lenses in cataract surgery [2]. Findings:
- uncorrected and corrected distance visual acuity — practically no difference: uncorrected acuity worse than 6/6 was found in 60% of participants in both groups;
- trifocal lenses performed better at near: in one study (60 participants), uncorrected near acuity worse than J2 occurred in 3% with a trifocal IOL and in 30% with EDOF;
- neither type showed a clear advantage in spectacle independence or on visual function questionnaires;
- glare and halos were reported for both types; the studies were too small to detect a significant difference.
The authors rated the certainty of the evidence as low, owing to risk of bias and imprecision of the estimates.
Meta-analysis by Karam et al., 2023
The meta-analysis included 22 studies (2,200 eyes) [3]. Trifocal IOLs gave better uncorrected and distance-corrected near visual acuity and more often achieved spectacle independence. Uncorrected distance and intermediate acuity, as well as halos, glare, contrast sensitivity and patient satisfaction, did not differ statistically. The defocus curve favoured trifocal lenses at near and EDOF at intermediate distance.
| Outcome | EDOF | Trifocal IOL |
|---|---|---|
| Distance (uncorrected) | Comparable [2, 3] | |
| Intermediate distance | Comparable; defocus curve favours EDOF [3] | Comparable [3] |
| Near (uncorrected) | Worse | Better [2, 3] |
| Spectacle independence | No clear advantage [2] | Advantage in meta-analysis [3] |
| Halos and glare | No significant differences found [2, 3] | |
Who is usually considered for EDOF
EDOF optics are more often discussed with patients who prioritise distance and intermediate-range tasks — computer, dashboard, kitchen — and who are willing to use spectacles for fine print. As with any extended-range lens, the outcome depends on patient selection: ocular surface and macular status, corneal astigmatism and aberrations, and realistic patient expectations. These are general guidelines; indications and contraindications are defined by the manufacturer's instructions for use for the specific IOL.
X-VIZ — the Agaaz EDOF lens
X-VIZ — an Agaaz extended depth of focus intraocular lens designed for distance and intermediate vision, with an aspheric optical profile. The full dioptre range, constants and technical specifications are given in the manufacturer's brochure and are available on request. Monofocal models and other platforms are on the page “Agaaz intraocular lenses”; for a comparison of materials, see the article “Hydrophobic vs hydrophilic IOLs”.
References
- Morozova TA. Intraocular lenses with extended depth of focus — a new technology for presbyopia correction: a review. Annals of the Russian Academy of Medical Sciences (Vestnik RAMN). 2024;79(4):318–326. [In Russian] doi:10.15690/vramn17915
- Tavassoli S, Ziaei H, Yadegarfar ME, et al. Trifocal versus extended depth of focus (EDOF) intraocular lenses after cataract extraction. Cochrane Database Syst Rev. 2024;7(7):CD014891. doi:10.1002/14651858.CD014891.pub2
- Karam M, Alkhowaiter N, Alkhabbaz A, et al. Extended depth of focus versus trifocal for intraocular lens implantation: an updated systematic review and meta-analysis. Am J Ophthalmol. 2023;251:52–70. doi:10.1016/j.ajo.2023.01.024
This article is intended for healthcare professionals and does not replace the instructions for use of a specific IOL. The cited publications concern the EDOF and trifocal lens classes and are not studies of Agaaz products. See also: X-VIZ EDOF IOL.
