Biomedical Engineering Reference
In-Depth Information
9.3.5 A
RTIFICIAL
S
PHINCTER
AND
O
CULAR
M
USCLES
Artificial sphincter and ocular muscles can also be made from the IPMNC by
incorporating thin strips of the actuators in a bundle form similar to the parallel
actuator configuration.
9.3.6 I
NCONTINENCE
A
SSIST
D
EVICES
Various configurations of IPMNCs may be used in medical applications involving
incontinence. In these systems, a patient can activate the muscles by means of a
push-button switch or the like, which is preferably battery operated, to prevent
leakage and control discharge.
9.3.7 C
ORRECTION
OF
R
EFRACTIVE
E
RRORS
OF
THE
H
UMAN
E
YES
AND
B
IONIC
E
YES
AND
V
ISION
Various configurations of IPMNC may be used in medical applications involving
dynamic or static surgical corrections of the refractive errors of the mammalian eyes. In
these systems, a patient can activate the muscles by means of a push-button switch or
the like, which is preferably battery operated, to prevent leakage and control discharge.
Described here are an apparatus and method to create an automatic or on-demand
correction of refractive errors in the eye by the use of an active and smart (computer-
controllable) scleral band equipped with composite IPMNC or IPCNC artificial
muscles. The scleral band is an encircling band around the middle of the eye's globe
to provide relief of intraretinal tractional forces, in cases of retinal detachment or
buckle surgery, by indentation of the sclera as well as reposition of the retina and
choroids. It can also induce myopia, depending on how much tension is placed on
the buckle, by increasing the length of the eye globe in the direction of the optical
axis and changing the corneal curvature.
By using the same kind of encircling scleral band, even in the absence of retinal
detachment, one can actively change the axial length of the scleral globe and the
corneal curvature in order to induce refractive error correction. Figure 9.47 depicts
the proposed surgical correction of refractive errors by active scleral bands to create
bionic eyes. The band has a built-in coil to be energized remotely by magnetic
induction and thus provide power for the activation of IPCNC muscles. The active
composite artificial muscle will deactivate on command, returning the axial length
to its original position and vision back to normal (emmetropic vision).
Figure 9.48 depicts the general configuration for surgical correction of myopia
and figure 9.49 depicts the general configuration for surgical correction of hyperopia
or presbyopia. The eye in figure 9.48(a) is myopic, or long, and thus short sighted;
the image is formed inside the eye and does not reach the macula. The band expands
the sclera outward to correct myopia (shorten the eye length and decrease corneal
curvature) as in figure 9.48(b). The eye in figure 9.49(a) is hyperopic, or short, and
thus far sighted; the image is formed outside and beyond the eye and does not reach
the macula. The band contracts the sclera inward to correct hyperopia (increase the
eye length and increase corneal curvature) as in figure 9.49(b).
