Page 101 - The Indian Optician Digital Edition November-December 2021

with laser refractive surgery in myopic
and hyperopic patients, as well as possible
subsequent cataract interventions. We are
suggesting something totally new that is also
not incompatible with any other ocular therapy.”
This inlay, unlike others that do exist, would
not prevent subsequent study of the retina
or macula and even surgical interventions,
according to Dr Salvador García-Delpech from
the Aiken Foundation.
This first totally transparent diffractive
inlay consists of a diffractive lens made of
a biocompatible material. Walter D Furlan,
researcher at the Department of Optics and
Optometry and Vision Sciences at UV, says that
“It is extremely thin – less than 5 microns – so
it would be inlayed inside the stroma of the
cornea, basically without affecting its structure,
in a cavity created with a femtosecond laser. The
lens is micro-perforated, which allows the flow
of necessary nutrients in this part of the cornea.”
Another feature that distinguishes it
from existing inlays is that the area where
the nutrients flow is greater. This reduces
the chances of rejection once inlayed in the
cornea of the patient. Also of note is that some
of its design parameters may be adapted,
which offers a new option for the treatment
of presbyopia, with the development of fully
customised trifocal corneal inlays to meet the
individual needs of each patient.
THROUGH-FOCUS VA CURVES FOR THE PDCI
(MAGENTA), AND RCI (BLUE) OBTAINED FROM THE
AMTFS USING EQ. (1). THE PUPIL SIZE IS 4.5 MM
AND THE ABSCISSA AXIS HAS THE ORIGIN (0.0 D
DEFOCUS) AT THE DISTANCE FOCUS OF EACH LENS.
IMAGES OF A TUMBLING E OPTOTYPE
CORRESPONDING TO 0.4, 0.2 AND 0 LOGMAR VA
OBTAINED THE VAO SYSTEM SIMULATING THE
PDCI AND RCI WITH THE OBJECT AT DIFFERENT
VERGENCES FROM 0.0 D TO − 3.0 D
There are multifocal intraocular lenses that
generally replace the crystalline lens of the eye
and intra-corneal inlays for surgical treatments.
According to the researchers, so far the two
types of intra-corneal inlays are small-aperture
inlays and refractive inlays.
While the first type produces an extension
of the depth of focus with which intermediate
vision is gained, their luminous efficiency is
low since it is partially opaque. The second
type achieves bi-focal vision, so it has a
good performance for those who are near-
sighted and farsighted, but it loses quality
at intermediate distances. The latest design
implant, according to the tests developed by
the researchers, overcomes all these handicaps.
In their tests, the team demonstrated
the viability of the new trifocal intra-corneal
inlay design by evaluating its optical quality
in comparison to another model currently
used in clinical practice. This was done first
numerically with commercial software and
then experimentally in an artificial eye using an
adaptive optics-based visual simulator.
These trials form part of Diego Montagud
Martínez's doctoral thesis, recently presented
at the UPV. This is being followed by starting
trials in patients, in a non-invasive way, with
the adaptive optics-based visual simulator.
The trials will be done in collaboration with the
Aiken Ophthalmology Clinic.
97 | PRESBYOPIA