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Description  |
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FIELD OF THE INVENTION
The present invention relates to the prescribing and forming of spectacle
lenses having particular utility where bifocal, trifocal, special
vocational or aphakic corrections are required.
SUMMARY OF THE PRIOR ART
At the present time most practicing opticians, optometrists and
ophthalmologists have in stock spectacle lenses with given curvatures and
corrections. These can range from plano to -12.00 diopters, and plano to
+12.00 diopters. It is also possible for the these ranges to extend to
higher powers but it is recognized that the standard operating procedure
within the ophthalmic industry is to carry only the lower power lenses as
described.
Spectacle retailers carry a range of stock lenses in inventory having the
capacity to make spectacles for normally 30% of their patients. However,
when any of these patients require a bifocal, trifocal, special vocational
or aspheric lens, the retailer must order the lens from a wholesale
grinding laboratory because his inventory of stock lenses is only capable
of filling single vision prescriptions.
This invention provides the spectacle retailer with a kit of very thin
veneer-type lens covers, each of which carries the particular bifocal,
trifocal, special vocational or aspheric correction required by that
particular patient. Prior art necessitated the use of a grinding
laboratory because it would be impossible to carry in stock all the
possible combinations of prescriptions, in addition to all the possible
bifocal, trifocal, special vocational or aspheric locations resulting from
each patient's particular facial measurements. The total inventory of the
prior art is far beyond even the largest retailers' capabilities including
those retailers large enough to having more than 2,000 locations.
This invention, by providing a kit of veneers to be optically laminated to
the eyeglass retailer's single vision inventory, gives the eyeglass
retailer the capability of providing spectacles for at least 90% of his
patients, within one hour or two.
The present state of the art does not provide for eyeglass retailers to be
able to add any available color tinting to their glass lens inventories.
These lenses must be sent away to special lens coating laboratories that
have extremely expensive (usually more than $150,000 ) glass coating
equipment. This invention permits that the veneer cover lenses sometimes
be made in CR-39 plastic which is tintable by the retailer just the same
as his other CR-39 plastic stock lenses.
Present practice and that of the prior art involves time and delay in
fitting the patient with the spectacles and loss of prompt delivery of a
set of glasses which are appropriate to his prescription. Many patients
with severe corrections are forced to carry one extra, or even two extra
pairs of eyeglasses, or have them available since without them their sight
is limited and functional capabilities are limited.
Some of the veneer lenses will also be provided in glass when desired. Thus
it becomes highly desirable to provide the eyeglass retailer with a
modular kit which will permit him to not only prescribe the appropriate
prescription for the patient, but deliver a complete set of spectacles
within a matter of one or two hours, and susceptible for immediate
verification as to comfort and visual accuracy.
The prior art may be found in Class 313, subclasses 478, 479; Class 350,
subclasses 417, 422, 444; and Class 351, subclasses 159, 168, 172, 176 and
includes U.S. Pat. Nos. 993,812; 1,267,014; 1,304,421; 1,948,636;
2,033,101; 2,330,663; 2,611,294; 3,248,460; 3,617,116; 3,628,854;
3,702,218; 3,771,858; 3,904,281; and 3,917,766.
SUMMARY OF THE INVENTION
The present invention stems from the development of an eyeglass lens module
in which two lens components are formed. The first component is the
conventional single vision stock lens having conventional corrections in
the negative or positive diopter range and, indeed, for the patient
requiring only bifocals or trifocals, the single vision stock lens can be
of zero correction. The second veneer over-lay lens component is desirably
formed of a plastic or glass material and is as thin as practical so that
it becomes a veneer cover. These veneer over-lays are in modules
containing bifocals or trifocals or vocational modifications of a given
diopter correction. They can also contain special vocational features such
as upper bifocals for airline pilots. Once the prescription is developed
according to the method of the invention, the optical glass lens blank is
then fixtured for receiving the veneer over-lay. Prior to the laminating
or gluing procedure, a sagittal gauge is applied to the posterior surface
of the veneer over-lay and the anterior surface of the single vision stock
lens, to determine that their curvatures are nearly equal to insure a
close physical inter-fit which, in turn, will help insure an optically
acceptable bond between the two. Desirably, the lens and the veneer
over-lay are cut and edged to the configurations of the frame which is
selected. Optionally they can be cut and edged before or after laminating.
Once the two lens components are secured to each other with an optical
cement which is applied with a rotary motion to minimize bubbles or other
optical distortions in the cementing action, they can then be fitted into
the spectacle frame and delivered to the patient. Furthermore, when
tinting is required the plastic veneer over-lay can be readily tinted by
conventional dye as distinguished from the expensive and time consuming
coating process required with the optical glass type lens.
In view of the foregoing, it is a principal objective of the present
invention to provide the practicing spectacle retailer (usually opticians,
optometrists and ophthalmologists), with a pre-selected number of veneer
over-lays containing bifocals, trifocals, vocational features and aspheric
corrections. The eyeglass retailer can use this present in-house inventory
of single vision glass or plastic lenses to be combined with the veneer
over-lays thus permitting extensive control over the eyeglass manufacture
to be in the hands of the party who has prescribed the particular
correction necessary for the patient.
A further object of the present invention is to provide the patient with
eyeglasses correct for bifocal, trifocal, special vocational or aspheric
fillings and also permits customized tintings in accordance with the
recommendations of the eyeglass retailer and/or prescribing doctor, as
well as the taste of the patient.
A further object of the present invention is to permit fitting the patient
requiring only a bifocal or trifocal correction with spectacles or
sunglass spectacles and giving prompt delivery.
A further object of the present invention is to provide the eyeglass
retailer with very inexpensive veneer over-lays which when combined with
his own in-house stock single vision lenses, create bifocals, trifocals,
special vocational and even aspheric lenses at a very reasonable cost, and
maximizing the productivity of the inventory.
The combined cost of the vener over-lays and single vision lenses is
inherently less expensive than the usual and customary cost of the same
prescription when ordered from the wholesale prescription grinding
laboratory.
A further object of this invention is to provide the consumer or patient
with prompt delivery and fitting of their prescription eyeglasses even
when bifocals, trifocals, special vocational, and aspheric designs are
involved, and at a substantially reduced cost because all the fabrication
can be done on the premises of the eyeglass retailer.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and advantages of the present invention will become
apparent as the following description of an illustrative embodiment of
both the apparatus and method proceeds, taken in conjunction with the
accompanying drawings, in which:
FIG. 1 is a diagrammatic view of a typical lens with a negative correction,
and example of a veneer over-lay;
FIG. 2 is a view in the same scale as FIG. 1 illustrating a veneer over-lay
bifocal in conjunction with a lens having a positive correction;
FIG. 3 is another view showing a different correction than shown in FIG. 2,
but utilizing a lens having posterior and anterior curvilinearity;
FIG. 4 is a similar example showing a typical sunglass or other eyeglass in
which the principal correction is zero, with a bifocal portion;
FIG. 5 is a front view of a typical single vision stock lens;
FIG. 6 is a front view of a typical single vision stock lens with the
veneer over-lay; and
FIG. 7 is a front view of a typical single vision stock lens with the
veneer overlay, but showing a trifocal lens segment.
As to each of the above, typical corrections are applied at the locations
designated by the reference numerals F1, F2, F3, and F4.
THE METHOD
The method of the present invention begins with the supplying of the
eyeglass retailer with optical glass or plastic corrective single vision
stock lenses. If the eyeglass retailer already has an inventory of these
stock lenses, then he may use the ones he already has on hand.
Next the eyeglass retailer is supplied with a pre-selected number of veneer
over-lays having the plus diopter bifocal or trifocal corrections. The
veneer over-lays are also formed with the conventionally used special
vocational features used in the industry.
The eyeglass retailer then selects the appropriate single vision lens from
his inventory and the appropriate bifocal, trifocal, or vocational veneer
over-lay. The veneer over-lays are selected with respect to their bifocal
or trifocal power, or other extra required features such as special
vocational segment, and also with respect to their posterior curvatures.
The posterior curvature of the veneer over-lay must be very similar to the
anterior curvature of the single vision stock lens for a complementary
close contact fit. The posterior surface of the veneer over-lay should
match the anterior surface of the single vision mount preferably within a
tolerance of plus or minus 0.06 diopter.
Optician's Procedure
The procedure for the use of the veneer over-lay modular system is best
described by giving some examples.
Prescription #1: R.E.+1.25 0.75.times.90
L.E.+1.75 0.50.times.85
Add +2.50 bifocal, Pink #1
Frame selected: #24, size 54/18
A - 54 B - 48 ED - 59
A patient having this prescription in hand with the above lens powers
enters the optician's office. The optician realizes the need for bifocal
lenses which heretofore would have required a telephone order to the
prescription grinding laboratory and a customary delay of 3 to 15 days to
acquire the lenses.
Step #1. The optician selects two single vision lenses from his inventory:
For the right eye a +1.25-0.75 and for the left eye a +1.75-0.50.
Step #2. Next the optician aligns these lenses in the Lensometer for the
axis and centration, as usual. At this point the optician must be sure
that the cylinders have been ground on the posterior surface of each lens,
so that the anterior surface is spherical and can be laminated to the
veneer over-lay.
Step #3. Next the optician applies the sagittal gauge to the anterior
surface of the single vision lenses to determine the anterior surface
curvature value in diopters.
In the above example, the value of these single vision lenses might be 3.66
mm.
Step #4. The next step is the selection of the veneer over-lay covers
having a sagittal value of 3.66 mm., and a bifocal power of +2.50 D.
Step #5. The veneer over-lays for this prescription must be susceptible to
tinting, such as CR-39 plastic, since the prescription requires color,
i.e. pink #1. The veneers are now tinted to the desired color using the
same procedure for tinting CR-39 plastic lenses.
Step #6. The veneer over-lays are now ready for bench layout.
Determining the `below` and `inset`
`Below`--The desired bifocal height is measured to be 20 mm. The B
measurement of the frame is 48, and when divided by 2 gives the vertical
mechanical center of the frame which is 24 mm. Subtract 20 mm. the desired
bifocal height, from the vertical mechanical center, 24. The result is the
`below` factor, i.e. 4 mm.
`Inset`--The frame P.D. is 54+18=72 mm. The patient's near P.D. is 60.
Subtract 60 from 72 and divide the result by 2. This gives the `inset`
required. In the above example, 6 mm.
Step #7. The veneer over-lay should now be placed over a protractor so that
the bifocal is positioned 4 mm. `below` and 6 mm. `in` from the mechanical
center. This procedure should be repeated for the right and left eyes
respectively, as is the usual customary procedure in these cases.
Step #8. The veneer over-lay may be laminated to the single vision lens at
this point, or they may be separately edged to the shape of the frame and
laminated in their `cut and edged` form. The decision becomes an
individual choice and will vary from one worker to the next.
Edge grinding of the lens components is the next step and is preferred
separately since conventional grinding wheels for optical glass and
plastic may or may not be compatible, and if the lenses are ground after
the veneer over-lay is optically secured to the single vision lens,
chipping can occur.
Once the two lens components are cut and edged for the size and shape of
the pre-selected patients frame, the single vision portion is desirably
placed on the fixture. Subsequently optical cement is dropped onto the
outer face of the single vision lens. Thereafter the veneer over-lay is
positioned atop the optical single vision lens, moved gently until the
optical cement, after eliminating bubbling, has been thoroughly spread at
the optical and physical interface between the two lenses.
Thereafter the two lens components are subjected to black light for about
10 to 15 seconds. This accomplishes a quick set while the two components
are in the gluing fixture. Once set, the lens components can be removed
from the fixture by hand and placed under a black light for one to three
hours accomplishing a full cure.
The Lens Structure
The single vision glass lens component is standard known in the industry
today. They are generally supplied by about two dozen major manufacturers
in a variety of prescription powers. These prescription powers are
generally supplied in one-quarter diopter increments and in both simple
and compound prescriptions. This includes corrections for hyperopia,
myopia, astigmatism and aphakia. The averages of the patients are well
known in the trade and therefore a larger supply of the most popular
corrections is carried by eyeglass retailers.
Usually eyeglass retailers carry inventories of standard prescription
single vision lenses made from either ophthalmic crown glass having an
index of refraction of 1.523, or ophthalmic plastic CR-39 lens material
having an index of refraction of 1.497. The present invention contemplates
that there are prescriptions specially in stronger powers, which could be
made significantly thinner, lighter and have more desirable cosmetic
attractiveness by using ophthalmic glass having higher indexes of
refraction, such as 1.701 through 1.805. The invention herein contemplates
supplying the single vision lenses of higher index of refraction when
needed.
The veneer over-lay lens components are normally formed of either plastic
or glass lens material. The index of refraction of the single vision lens
has no relationship with the index of refraction of the material of the
veneer over-lay. The veneer over-lay has no prescriptive power except for
the special feature which it carries including, but not limited to,
bifocal segments, trifocal segments, and special vocational combination
segments. Since the veneer over-lay has no power of its own, except for
the feature, its manufacture is contemplated of standard ophthalmic crown
glass having an index of refraction of 1.523 and/or CR-39 ophthalmic
plastic with an index of refraction of 1.497. This invention also
contemplates that the veneer over-lays may be mounted onto base lenses
having any index of refraction.
Various selections from given patient prescriptions are set forth in the
drawings commencing with the minus diopter corrections for the
near-sighted person and progressing to the plus diopter corrections for
the far-sighted person and ndeed into the area of aphakia. Contemplated
also are examples of the veneer over-lay having no distance prescription
power, but which carry the bifocal, trifocal, vocational, or aspheric
components needed for the completion of the prescription.
Although particular embodiments of the invention have been shown and
described in full here, there is no intention to thereby limit the
invention to the details of such embodiments. On the contrary, the
intention is to cover all modifications, alternatives, embodiments, usages
and equivalents of eyeglass lens modules, as fall within the spirit and
scope of the present invention, specification, and appended claims.
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