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Non-Diffractive EDOF IOLs Gaining Ground
Distance and intermediate vision improve with less glare and halos than diffractive alternatives. Howard Larkin reports from the 2022 ASCRS Annual Meeting
Minimonovision with EDOF #2 (Vivity)
• 59 patients (97 eyes) • Dominant eye emmetrope und non-dominant eye -0.5 D • 87% reported complete spectacle independence • Binocular defocus curve A) minimonovision B) emmetropia LogMAR
-0.2
0.0
0.2
0.4
2.0 1.5 Defocus Curves
CURVE A CURVE B * = p < 0.05
20/12.5
20/20
20/32
20/50 Snellen
1.0 0.5 0.0 -0.5 -1.0
-1.5 Defocus (D)
-2.0 -2.5 -3.0 -3.5
Mini-monovision with non-diffractive EDOF IOLs improves near vision and can increase spectacle independence.
When it comes to treating presbyopia, non-diffractive extended depth of focus intraocular lens (EDOF IOL) technology is the “new kid on the block,” according to Thomas Kohnen MD, PhD, FEBO. These lenses can reduce optical disturbances such as glare and halos while offering similar depth of focus gains compared with diffractive EDOF and some multifocal IOLs.
For example, in a study Prof Kohnen conducted, 25% of patients implanted with the non-diffractive AcrySof® IQ Vivity™
IOL (Alcon) reported halos compared with rates of 60% to 70% reported for diffractive IOLs.i The non-diffractive Vivity scored better on night visual acuity and produced less glare and halos than the same manufacturer’s PanOptix® trifocal—though the trifocal provided better near visual acuity, he added.
Other studies have found bilateral Vivity patients have similar rates of spectacle independence with some diffractive multifocals.ii
MINI-MONOVISION Implanting the Vivity targeting mini-monovision, with the dominant eye emmetropic and the non-dominant eye at -0.50 D, expanded the effective defocus range, resulting in 87% spectacle independence in a study Prof Kohnen co-authored—comparable to the bilateral PanOptix spectacle independence rate.iii A similar study also showed better near vision targeting -0.25 D to -0.50 D in the non-dominant eye.iv
“You can have an advantage using mini-monovision in these patients,” Prof Kohnen said.
In some studies, diffractive EDOF IOLs deliver similar patientreported quality of vision as similarly designed monofocal lenses. For example, Mini WELL® IOL (SIFI Medtech) uses an engineered aspheric wavefront optic to extend depth of focus, broadening the defocus curve to offer better intermediate and near vision than the same manufacturer’s monofocal Mini 4, with low optical disturbances. Measurements of internal higher order aberrations revealed a greater negative primary spherical aberration in the EDOF group at pupil sizes of 2.0 to 5.0 mm. At 5.0 mm, total internal HOAs did not differ significantly between the two groups.v
While patients tend to be satisfied with their better intermediate and even near vision with any EDOF IOLs, “the basic message always comes to how are these diffractive lenses and other types of lenses actually working in terms of visual disturbances,” Prof Kohnen said. And non-diffractive models may hold the edge.
“I think non-diffractive lenses will be a choice in the future, and mini-monovision with non-diffractive EDOF lenses may make some patients spectacle independent. So, it’s a good choice for patients who want less spectacle dependence after cataract or refractive surgery,” he concluded.
Thomas Kohnen MD, PhD, FEBO
i Kohnen T et al. Journal of Cataract & Refractive Surgery. 2022 Feb 1; 48(2): 144–150. ii Hovanesian J et al. Clinical Ophthalmology. 2022 Jan 18; 16: 145–152. iii Coassin M et al. European Journal of Ophthalmology. 2021 Nov 26; 11206721211064018. iv van Amelsfort T et al. Journal of Cataract & Refractive Surgery. 2022 Feb 1; 48(2): 151–156. v Greve D et al. Journal of Cataract & Refractive Surgery. 2021 Sep 1; 47(9): 1139–1146.
Thomas Kohnen MD, PhD, FEBO is professor and chair, Department of Ophthalmology, Goethe University, Frankfurt, Germany, and ESCRS treasurer.
FOCAL TRABECULAR MICRO-BYPASS PRODUCES CIRCUMFERENTIAL DILATION OF SCHLEMM’S CANAL
Kevin Gillmann MD,
MBBS, MBA, FEBO, March, PgCert. (Harvard) is a glaucoma specialist, an honorary fellow at Moorfields Eye Hospital, and the editor of the upcoming Elsevier textbook “The Science of Glaucoma Management”.
The anatomical effect of iStent inject® trabecular micro-bypass on Schlemm’s canal and the role of preserving trabecular structures in the treatment of mild-to-moderate glaucoma
With the development of minimally invasive glaucoma surgery (MIGS), the question of whether to bypass, dilate, stent, cleave, tear or preserve Schlemm’s canal and the trabecular meshwork TM has become a hot topic in glaucoma. In a study published in the Journal of Glaucoma(1), we used anterior segment OCT to assess the anatomical effect of iStent inject® implantation combined with cataract surgery on angle anatomy in 54 eyes with mild-to-moderate openangle glaucoma. Twelve months after surgery, we observed a significant dilating effect of Schlemm’s canal in operated eyes. Compared to unoperated fellow eyes, Schlemm’s canal’s major diameter was 74.5% greater next to the bypass, and 45.7% greater at the opposite limbus(1). This suggests that a focal trabecular bypass may achieve circumferential Schlemm’s canal dilation solely through an increase in aqueous flow, as opposed to a mechanical dilation as can be seen in some techniques involving viscodilation or the use of scaffolding devices.
While concurrent cataract surgery may have had a contributing effect, Zhao et al.(2) observed a more modest dilation of Schlemm’s canal following standalone cataract extraction. However, Yang and colleagues’(3) observation that high intraocular pressures and glaucoma cause the collapse of Schlemm’s canal, with structural adhesions and herniations, leads us to hypothesise that the effect may become less as glaucoma progresses. Nevertheless, this ability to restore Schlemm’s canal dimensions is particularly relevant as Allingham et al.(4) showed that its reduced diameter accounts for nearly half of decreased outflow facility in glaucoma. Mean dimensions of Schlemm’s canal measured 500 micrometers away from the sites of iStent inject® implantations (left) and at the temporal limbus in unoperated fellow eyes (right)(1) . In fact, seeking to restore the TM’s physiological functions as a therapeutic strategy, rather than simply trying to bypass or remove it, may have several benefits. First, Johnstone et al.(5) have described how aqueous outflow is an active process driven by a mechanical pump relying on trabecular motion and interconnected inlet/outlet valves. Therefore, removing one side of this intricate system may be counterproductive in promoting outflow. Then, some authors have speculated that the TM and its cells’ intense phagocytic activity may play a key role in preventing more distal outflow obstructions. Finally, preserving the blood-aqueous-barrier at the level of the TM may reduce the inflammatory component involved in some types of glaucoma and ocular pathologies.
In conclusion, increasing aqueous outflow facility through a very focal intervention such as the implantation of an iStent inject® micro-bypass may be sufficient to produce circumferential dilation of Schlemm’s canal in mild-tomoderate glaucoma. Focal interventions have the added advantage of preserving the integrity and physiological functions of angle structures that may contribute to aqueous outflow through different mechanisms.
Mean dimensions of Schlemm’s canal measured 500 micrometers away from the sites of iStent inject® implantations (left) and at the temporal limbus in unoperated fellow eyes (right)(1) .
Mean difference in Schlemm’s canal major diameter in operated eyes 12 months after iStent inject® implantation and cataract surgery (left) compared to unoperated fellow eyes (right)(1)
References: 1. Gillmann, Kevin, et al. “A prospective analysis of iStent Inject microstent implantation: surgical outcomes, endothelial cell density, and device position at 12 Months.” Journal of Glaucoma 29.8 (2020): 639-647. 2. Zhao, Zhennan, et al. “Schlemm’s canal expansion after uncomplicated phacoemulsification surgery: an optical coherence tomography study.” Investigative Ophthalmology & Visual Science 57.15 (2016): 6507-6512. 3. Yang CY, Liu Y, Lu Z, Ren R, Gong H. Effects of Y27632 on aqueous humor outflow facility with changes in hydrodynamic pattern and morphology in human eyes. Invest Ophthalmol Vis Sci 2013;54:5859-5870. 4. Allingham, Rand R., Annelies W. de Kater, and Ross C. Ethier. “Schlemm’s canal and primary open angle glaucoma: correlation between Schlemm’s canal dimensions and outflow facility.” Experimental eye research 62.1 (1996): 101-110. 5. Johnstone, Murray A. “The aqueous outflow system as a mechanical pump: evidence from examination of tissue and aqueous movement in human and non-human primates.” Journal of glaucoma 13.5 (2004): 421-438. PM-EU-0205
