This document discusses parameters for achieving an extended depth of field (EDoF) intraocular lens. It notes that chromatic aberration (LCA), spherical aberration (SA), refractive index (RI), Abbe number, and high order aberrations (HOA) can influence EDoF, and that LCA, SA, and HOA can potentially be addressed through diffractive optics, aspheric profiles, and low add designs. Specific EDoF lenses discussed include the Zeiss At Lara, Tecnis Symfony, Mini Well, Oculentis Comfort, and IC-8, highlighting their optical performance and ability to extend depth of field while maintaining good visual quality.
6. S.FRANSSENS
Parameters to achieve an EDoF lens?
6
LCA
(chromatic
aberrations)
SA
(spherical
aberrations)
RI
(refractive
index)
Abbe N
(abbe
Number)
HOA
(High order
aberration)
8. S.FRANSSENS
Refractive index
How much light slows down as it travels through a material
Higher index
material requires
less convexity.
Benefit from a thin
profilewww.co-ophthalmology.com Volume 27 Number 4 July 2016
8
9. S.FRANSSENS
Refractive Index
How much light slows down as it travels through a material
Higher index material
demonstrates greater
REFLECTANCE
Unclear how sensitive patients are to such reflections…
1. Glistenings
2. Positive and
negative
dysphotopsias (?)
www.co-ophthalmology.com Volume 27 Number 4 July 2016
9
12. S.FRANSSENS
Chromatic aberration
LCA & TCA
Dispersion on
the axial axis
Off-axis
dispersion
Blurry or « waxy »
images
Rainbow edge
blurring
For most human eyes, the impact of LCA is thought to be
greater than the impact of all higher-order aberrations
Zhai Y, Wang Y, Wang Z, et al. Construction of special eye models for
investigation of chromatic and higher-order aberrations of eyes. Biomet Mater
Eng 2014; 24:3073–3081.
12
14. S.FRANSSENS
Key factor for LCA: « ABBE » number
Abbe number indicates how the refractive index (RI) material
changes with wavelength of emitting light.
• Change of RI with wavelength
chromatic aberration
• Larger Abbe # less chromatic
aberration
14
15. S.FRANSSENS
Positive and negative LCA
REFRACTION : Power RED light < Power GREEN light < Power BLUE light
DIFFRACTION : Power RED light > Power GREEN light > Power BLUE light
Refraction
(FAR):
Diffraction
(NEAR and INTER):
Refractive LCA
Diffractive LCA
>0
<0
24. S.FRANSSENS
HOA values
In a Population average ,
most HOA terms average is 0
The optical quality of the eye is limited by
optical aberrations, diffraction and scatter.
Aberration
order
24
Sine/
Cosine
25. S.FRANSSENS
HOA’s RMS
HOA are those equal to
or above n=3
Cannot be corrected by
spectacles
RMS@6mm = 0,38µm
≥0,56µm
Good candidates for
MIOL’s ?
25
30. S.FRANSSENS
Patient Benefits with Aspheric Lenses
BCVA not improved with aspheric IOL
Better contrast sensitivity , particularly
under dim lighting conditions.
Spherical aberration can vary
significantly from patient to patient
= Lasik patient (negative )
30
38. S.FRANSSENS
« Oculentis Comfort » = BIFOCAL LOW ADD
linical Results
Prof. Dr. Jorge Alió, University Ophthalmology Clinic, Miguel Hernandez,
Alicante, Spain
In a comparative study by the Vissum Ophthalmology Institute (Alicante,
Spain) under the management of Professor Alió, the visual results and the
optical quality of the LENTIS Comfort and of a so-called accommodating lens
were observed, and evaluated post-operatively in just under 40 patients and
66 implanted eyes. The LENTIS Comfort produced, for all distances, in
particular in the wide intermediate range, considerably better visual acuity
results than the accommodating IOL.
38
