HK1209493B - Contact lenses for myopic eyes and methods of treating myopia - Google Patents

Description

Contact lenses for myopic eyes and methods of treating myopia

This application is a divisional application of the chinese patent application having application number 201180012186.7 entitled "contact lens for myopic eye and method of treating myopia".

Technical Field

The field of the invention is contact lenses for myopic eyes and methods of treating myopia. In particular, the contact lenses of the present invention and related methods may be applicable to myopic eyes that are not substantially presbyopic. Embodiments of the present invention are applicable to myopic eyes in which myopia is progressing.

Background

Many people suffer from myopia (short-sight). The prevalence of myopia is increasing. Thus resulting in increased concentration on the development of solutions. Furthermore, for many people, myopia deteriorates over time despite being corrected using some existing methods.

Figure 1 shows an eye with normal vision (i.e. neither hyperopia nor myopia). FIG. 2 shows a myopic eye viewing a distant subject; the focus of the image is in front of the retina. This offset focus relative to the retina can blur vision.

Several techniques have been used to correct myopia. These techniques include the fitting of lenses or contact lenses or intraocular lenses, surgical reshaping of the cornea and temporary reshaping of the cornea by hard or soft contact lenses.

When looking at near objects, it has been found that many people with myopia do not adjust their vision to the extent sufficient to advance the image onto the retina. This under-regulation is commonly referred to as lag of regulation (lag of accommodation). FIG. 3 shows a myopic eye with accommodative lag; the focus of the image is located behind the retina. Studies involving children indicate that lag of accommodation increases with increasing near focus (i.e., accommodation) demand. In a study involving children of predominantly european descent, median hysteresis was found to be 1.26D (ranging from-0.75 to 2.82D) in children 8 to 11 years of age, measured at 33 cm using a computer optometrist. In children of Chinese descent, the lag of accommodation measured at 33 cm was 0.74 +/-0.27D.

Patent publication EP 2004/005560 a1 to Radhakrishnan et al describes a method of retarding or controlling the progression of myopia by controlling aberrations to manipulate the position of medium and high spatial frequency spikes of a visual image in a predetermined manner. The adjusted positions of the medium and high spatial frequency spikes are used to change the accommodative lag. The method requires providing an ophthalmic system having a design that can control a predetermined aberration and requires a design that can provide a negative spherical aberration.

International patent publication WO 05/055891a1 describes the use of contact lenses to control the relative tortuosity of field of view (curvature of field) with the goal of controlling the progression of myopia. The method includes moving the peripheral image forward relative to the retina and allowing clear central vision.

U.S. patent No. 6,752,499(Aller) describes the use of multifocal contact lenses to control the myopic progression of a myopic eye under an internal fixation disparity. Aller describes providing contact lenses that result in acceptable distance vision and that reduce or correct esophoria at near. Aller describes the use of near-center, refocus contact lenses with add powers up to 2.25D and the use of far-center contact lenses with add powers up to 2.5D.

Multifocal and bifocal contact lenses have also been designed for presbyopia.

U.S. Pat. No. 6,457,826(Lett) describes a center near bifocal contact lens and a center far bifocal contact lens. The described embodiment of a central near bifocal contact lens has a constant power central zone extending to a chord diameter of 2.07 mm, a distance power outer zone starting from a chord diameter of 2.71 mm, and a gradient power aspheric zone providing continuous power transitions from the central zone to the outer zone. For a 3.0 mm pupil, Lett indicates that the near power occupies 48% of the pupil area, while the distance power occupies 18%. For a 5.0 mm pupil, Lett means that the near power occupies 17% of the pupil and the distance power 71%.

Us patent 5,139,325(Oksman et al) describes a contact lens having a vision correcting refractive power inversely proportional to the radial distance of the contact lens. In one described example, the contact lens has an add power (add power) of 2.75 diopters over distance vision over a radius of 0.72 millimeters, which decreases inversely with radius beyond the radius of 0.72 millimeters. Another example has an add power of 3.00 diopters over distance vision over a maximum 0.66 millimeter radius. Unless this function is truncated, the add power will not go to zero.

U.S. patent 5,754,270(Rehse et al) describes a contact lens having a central aspheric zone with an add power of between 2.25 and 2.5D over distance vision at a maximum diameter of about 2.4 mm, a change in add power of about 0.5 to 1.25D over an area between 2.4 mm and 2.50 mm diameter, and then a progressive reduction in add power until the power required for distance vision correction is achieved at about 6 mm diameter.

Any prior art mentioned within this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected, determined, understood and regarded as having significant relevance by a person skilled in the art.

Disclosure of Invention

The present invention relates generally to contact lenses and the use of contact lenses for the treatment of myopic eyes.

The contact lens includes an inner optic zone and an outer optic zone. The outer optic zone includes at least one portion having a first refractive power selected to correct distance vision. The inner optic zone has a relatively more positive power (add power). In some embodiments, the add power is substantially constant over the inner optic zone. In other embodiments, the add power is variable across the inner optic zone. While in some embodiments the inner optic zone has a power designed to substantially eliminate the lag of accommodation of a myopic eye, in other embodiments the add power may be higher, for example up to about 4 diopters.

All references to correction of distance vision include providing a contact lens having a first refractive power that substantially eliminates blurred vision.

In some embodiments, the outer optic zone includes at least one portion having a third power that is relatively more positive than the first power. The portion having the third refractive power is different from the inner optic zone; the third refractive power is separated from the inner optic zone by a portion having the first refractive power. The third power may be substantially equal to the add power if the add power is constant, or the maximum add power in the inner optic zone if the add power is variable. Alternatively, the third optical power may be different from the second optical power. In some embodiments, the third power is relatively more positive than the add power.

In some embodiments, the outer optic zone includes at least two portions of relatively more positive power than the first power, separated by a portion having the first power. In some embodiments, the at least two portions each have the same optical power. Alternatively, the at least two portions each have a different refractive power. When the powers are different, the portion having a relatively more positive power is located at a greater radial distance on the contact lens than the portion having a relatively less power.

In some embodiments, the inner optical zone comprises a meridian extending through the optical zone.

In some embodiments, the diameter of the inner optic zone and/or other add power portions of the contact lens are selected to be at a maximum and still maintain acceptable distance vision. The selection may be a repetitive method that takes into account the deterioration of myopia and the effect of the portion of the contact lens having add power on distance vision.

In some embodiments, the inner optic zone is located off-center from the center of the contact lens. In these embodiments, the corneal contact lens is configured to have an orientation when worn on the eye such that the inner optic zone is located off-center from the nasal direction.

In some embodiments, any zone of the eye that corrects ametropia of distance vision can correct ametropia, thereby providing substantially clear distance vision.

A method of providing a contact lens for a myopic eye comprising providing a contact lens as described above comprising a portion having a refractive power which corrects distance vision and a portion having an additive refractive power. Thus, the locations and/or the power profile and/or the magnitude of the add power may be varied with the goal of affecting the rate of myopia progression and/or maintaining acceptable distance vision.

A series of contact lenses may be provided to select contact lenses having different characteristics as described above and need not be customized for individual wearers.

Further general aspects of the invention and further embodiments of the aspects described in the preceding paragraphs can be seen from the following description and/or from the drawings.

Drawings

Fig. 1 shows an eye with normal vision.

Fig. 2 shows a myopic eye viewing a distant subject.

FIG. 3 shows a myopic eye with accommodative lag.

Fig. 4 shows a plan view of an embodiment of the contact lens of the present invention.

Fig. 5 shows a cross-section of the contact lens of fig. 4.

Fig. 6 shows a myopic eye viewing a distant object through the contact lens of fig. 4.

Fig. 7 shows a myopic eye viewing a near object through the contact lens of fig. 4.

Fig. 8 shows a graph of relative power versus radius for several embodiments of contact lenses according to the invention.

Figure 9 shows a treatment profile for myopia with increased relative tortuosity of field.

Fig. 10 shows a plan view of another embodiment of the contact lens of the present invention.

Detailed Description

1. Preamble of preamble

As briefly described above, a myopic eye may experience a lag in accommodation when viewing a near object. A greater degree of retardation of accommodation may be associated with an exacerbation of myopia. Due to this lag, the retina may be affected by blurring or defocusing (hyperopia) when reading a near sentence or object. This blur or defocus has been theoretically presumed to be a stimulus for eye growth.

A mechanism that can reduce accommodative error is to use a positive lens (which is a lens with positive power relative to the distance power of the lens) at near viewing. The positive power may bring the image closer to the retina, thus reducing or eliminating lag of accommodation. Bifocal or multifocal lenses, such as progressive addition lenses (the upper region of which is provided for distance vision and the lower region of which is provided with a positive power for near viewing relative to the distance region) may be used to provide such additional positive power for near viewing.

A dispute relating to the use of glasses is the adaptability to view near objects. In order for the lens to be effective, the lower part of the lens having an additional positive refractive power should be used when viewing a near object, however, since there is no incentive to conduct observation through the lower part of the glasses, when watching a near object, a patient (especially a child) tilts the head downward and continues to use the far part of the lens instead of the near part.

In this case, the contact lens may provide better compliance because it is aligned with the eye, thus eliminating the need for the eye to move with the head. Also, in the case of the eyeglass wear, even in the case where the child observes through the lower position of the eyeglass, since observation variation and eye movement occur behind the eyeglass, it is difficult to align an appropriate refractive power with the eye at any time. Given that the contact lens is placed on the anterior surface of the eye and is perfectly aligned with the eye movement, a contact lens with the appropriate power profile ensures that the child receives the appropriate corrective power at all viewing distances.

2. Contact lenses having zones of different refractive power

Fig. 4 shows a plan view of an embodiment of a contact lens 100 for correcting myopia. The contact lens 100 includes 3 zones and a transition zone. These 3 zones are the inner optic zone 1, the outer optic zone 2 and the outer peripheral zone 3. A transition zone 4 is located between the inner optic zone 1 and the outer optic zone 2, all within the outer peripheral edge 5 (which is represented in dashed lines in figure 4) of the contact lens.

Fig. 5 shows a cross-section through the diameter of the contact lens 100. In the illustrated embodiment, the contact lens 100 has rotational symmetry. The manufacture of rotationally symmetric lenses is simpler than the manufacture of asymmetric lenses. However, as explained below, certain embodiments of contact lenses are asymmetric. The contact lens comprises an anterior surface 6 and a posterior surface 7.

The contact lens 100 may be a soft or hard corneal contact lens. For example, the contact lens may be a silicone-hydrogel corneal contact lens or a hard, gas permeable corneal contact lens. Alternatively, the contact lens 100 may be a corneal inlay provided on the cornea, under the epithelium, which may have been scraped off and regrown on the contact lens, for example. If the contact lens is a hard contact lens or a corneal inlay, the peripheral zone 3 may be omitted.

2.1 size and refractive power of the inner optic zone

The diameter D1 of inner optic zone 1 is approximately equal to or less than the pupil diameter P1 during viewing of a near object. P1 is typically between 2 and 4 mm depending on the wearer of the contact lens. The close distance may correspond to a distance with negligible or no substantial lag in accommodation. The inner optic zone 1 may be about 10% of P1 up to about 100% of P1. However, for many contact lens wearers, it is contemplated that a suitable diameter D1 for the inner optic zone 1 can be selected from the range of 50% to 100% of P1.

The power of the inner optic zone 1 is relatively more positive than the power of the outer optic zone 2. The differential power of the inner optic zone 1 to the outer optic zone 2 can be selected from the range of about 0.5D and 4.00D. For example, if the outer optic zone 2 has a power of-1.50D, the inner optic zone may have a power of from about-1.00D to 2.50D.

In some embodiments, the power of the inner optic zone 1 is selected taking into account the lag of accommodation of a myopic eye when viewing near distances. For example, the optical power may be selected to substantially reduce or eliminate lag of accommodation. The power may then be selected to be substantially uniform over the inner optic zone 1. This approach may be particularly suitable when the inner optic zone 1 is large (i.e., 50% or more of P1). In other embodiments, whether or not the inner optic zone is 50% or higher of P1, the power may be different and at least a portion of the add power may be higher than that required to correct lag of accommodation over the extent of the inner optic zone 1.

Embodiments in which the add power of the inner optic zone is higher than that required to correct lag of accommodation may be particularly suitable if the inner optic zone 1 is less than 50% of P1.

The choice of the smaller or larger inner optic zone 1 can be based on the pupil diameter of the contact lens wearer, the subjective acceptability of the contact lens 100, and taking into account the necessary proportion of positive power zones (see below).

In the embodiments described in this patent specification, the inner optic zone 1 is shown as extending from the center of the contact lens to a diameter to represent a solid disc when viewed from the anterior surface of the contact lens. The inner optic zone 1 may however have another shape than circular, but this adds complexity to the manufacture.

2.2 outer optic zone diameter and refractive power

The outer optic zone 2 has an annular shape with an inner diameter equal to D1 (when the zones are measured from the midpoint within the transition zone 4) and an outer diameter D2. The outer diameter D2 approximates the pupil diameter P2 during viewing of distant objects. Depending on the patient, P2 is typically between 3 and 8 mm. In other embodiments, the outer optic zone 2 may be larger than P2.

The outer optic zone 2 has a refractive power selected to take into account the myopic condition of the eye to which the contact lens 100 is to be worn. For example, in many embodiments, it is desirable to select a refractive power that will result in substantially clear distance vision for the eye. In some embodiments, the outer optic zone 2 has a substantially constant power with increasing radius. In other embodiments, the outer optic zone 2 may comprise a plurality of sub-zones having different optical powers. In these other embodiments, a large proportion of the outer optic zone 2 is still allocated to correcting distance vision in the myope.

2.3 selection and adjustment of contact lens design parameters

The proportion of the contact lens occupied by the addition power zone or zones relative to the distance correction zone can be adjusted by adjusting any one or a combination of the following variables:

the size of the inner optic zone;

the power profile of the inner optic zone (e.g., whether it has substantially uniform power over its inner diameter or whether it has several powers over the radius, such as a smooth aspheric relationship or a stepped relationship);

the power profile of the outer optic zone.

In some embodiments, about 40% to 50% of the total field of view is allocated to correct distance vision when the eye is viewing a distant object under normal indoor lighting conditions. In other embodiments, about 50% to 60% are allocated to correcting distance vision. In other embodiments, at least 70% is allocated to correcting distance vision.

A method of treating myopia therefore includes a method of repeating dispensing a contact lens wherein a first proportion of the contact lens is dispensed for distance vision and a second proportion is dispensed for one or more zones of relatively positive refractive power. The distance vision is then evaluated and the relative proportion of the distance vision correction zone to the relatively positive power zone is varied to achieve or more closely approximate the necessary proportion of positive power zone while maintaining acceptable distance vision. The necessary ratio may be the maximum value that still maintains acceptable distance vision.

For example, the method may include starting with a contact lens having an inner optic zone with a diameter D1 and a diameter D2, and wherein diameter D1 is substantially equal to the pupil diameter when the patient is viewing a near object under normal room lighting conditions, and diameter D2 is substantially equal to or greater than the pupil diameter P2 when the patient is viewing a far object under the same lighting conditions. The patient's distance vision can then be assessed. If the distance vision is acceptable, the proportion of relatively positive power can be selectively increased by increasing the diameter of the inner optic zone and/or providing a positive power sub-zone in the outer optic zone. The patient's distance vision can then be reevaluated and the ratio adjusted if necessary. For example, as the patient's myopia progresses beyond a certain level and/or according to accommodative lag and/or according to the degree of defocus as measured at the peripheral retina. The method of increasing the proportion of positive power at acceptable distance vision (which may include patient acceptance) may be employed as a criterion for limiting the proportion. This method may be used, for example, if the patient's vision deteriorates by more than 0.5D per year or more than 0.7D or 0.8D per year. If the distance vision is not acceptable, the diameter of the inner optic zone and/or the size of any relatively positive power zone in the outer optic zone may be reduced or eliminated.

In addition to or instead of changing the ratio of the relatively positive power regions, the relative positive power of the positive power regions may be changed using similar methods as described above (e.g. increasing the power of the positive power regions until an acceptable limit for distance vision is reached (perhaps below the buffer value). Also, as described above, the power profile may be varied over the inner optic zone (i.e., the power may be constant or variable) and the rate of change may be different and/or the magnitude of the change may be different over the inner optic zone.

After wearing the initial contact lens 100 for a period of time (e.g., 3 to 6 months or 12 months), the rate of progression of myopia can be referenced to design a contact lens suitable for the patient. For example, a practitioner may start with a contact lens having an inner optic zone 1 with a diameter D1 and a diameter D2, where D1 is substantially equal to the pupil diameter when the patient is viewing a near object under normal room lighting conditions, and diameter D2 is substantially equal to or greater than the pupil size P2 when the patient is viewing a far object. The entirety of the outer optic zone 2 is used to correct distance vision. After the evaluation period has expired, myopia progression (if any) is measured, and if the progression exceeds a certain threshold, such as an annual rate above 0.5D (or in other embodiments, 0.7D or 0.8D per year or other rate of decrease that can be identified as necessary upon progression as compared to the contact lens 100 before wear), then the increased proportion of the contact lens can be used for the relative positive power and/or the relative positive power that can be added to one or more regions of positive power and/or the profile of the inner optic zone can be altered, such as from the general profile of contact lenses L1-L3 to the general profile of contact lenses L4-L6 (see also FIG. 8).

The choice of refractive power of the contact lens is taken into account to design a contact lens suitable for the patient. For example, the practitioner may select the outer optic zone for distance vision correction to insufficiently correct myopia, e.g., by about 0.5D or about 0.25D difference. It has been theorized that inadequate correction, at least for some patients, may help reduce the rate at which myopia deteriorates.

For example, a practitioner may:

1. identifying the required myopia correction and making adjustments if necessary, for example, insufficiently correcting the myopia: this will set the power of the outer optic zone 2;

2. the relatively positive refractive power required to focus light rays from near objects to image points closer to or on or in front of the retina is confirmed: this will determine the power of the inner optic zone 1;

3. identifying the power of any relatively positive power sub-zones within the outer optic zone 2, which may be initially selected to conform to the power characteristics in step 2;

4. the relative proportion of positive power to distance correction is adjusted as described above.

After the patient has worn the contact lens for a period of time, the practitioner may:

5. re-evaluating the patient's vision and confirming any correction required for the relative refractive power and/or the relative proportion of positive to far correction zones;

6. a second contact lens having the adjusted power profile is provided.

The practitioner may of course continue to monitor the patient and repeat the above steps periodically to maintain acceptable vision and respond to measured myopic progression, if any.

An example of this power profile is described below with reference to figure 8 and it will be appreciated that each of them can be modified to obtain any necessary proportion of a distance correcting region and a region of relatively positive refractive power.

2.4 transition zone

The transition zone 4 between the inner optic zone 1 and the outer optic zone 2 modulates the inner and outer optic zones to provide a continuous power profile. The transition zone 4 may be provided if the power at the outer peripheral portion of the inner optic zone 1 and the power at the inner portion of the outer optic zone 2 change in steps. In other embodiments, if the power in the inner optic zone 1 and/or the outer optic zone 2 varies with diameter and the two intersect, then a separately designed transition zone 4 is not required (which is an inherent part of the design). In some embodiments, the transition zone may be narrow, and thus the power profile may effectively include discontinuities.

2.5 peripheral zone

The peripheral zone 3 is shaped to rest against the sclera of the eye and serves to locate and retain the contact lens in place. As previously mentioned, when the contact lens 100 is a corneal inlay, the peripheral zone 3 may be omitted.

2.6 Effect of the contact lens

Fig. 6 and 7 show a myopic eye viewing a far object and a near object through the contact lens 100 shown in fig. 4 and 5. In fig. 7, the dashed line represents the path of light through the contact lens 100, while the solid line represents light for comparison without the contact lens 100. In this example, the contact lens 100 has been designed to focus light from a near object passing through the central optical zone onto the retina, or in other words, the inner optical zone 1 has been designed to remove lag of accommodation by placing an image of a near object on the retina. Fig. 6 and 7 show only the rays of the contact lens portion designed for the distance of the respective object. Specifically, the method comprises the following steps: figure 6 only considers light passing through the portion of the outer optic zone 2 that has been designed to correct distance vision and does not consider light passing through the portion of the inner optic zone 1 that is relatively positive refractive; fig. 7 only considers the light rays in the region of the inner optical zone 1 that have been retarded by the complete correction.

2.7 Power Curve embodiments and misalignment of the pupil center and the contact lens center

Figure 8 illustrates a possible power profile across the inner optic zone 1 and outer optic zone 2, indicated by the radius of the contact lens. The graph is drawn to show the power difference of the contact lens relative to the power required to correct distance vision in myopes. In fig. 8, the relative power difference is scaled in units of power in diopters (D) on the vertical axis, while the radial distance (or simply radius) from the contact lens axis is scaled in millimeters on the horizontal axis. FIG. 8 shows the curves for 6 different multi-zone contact lenses (L1-L6), in which:

l1 has an inner zone 1 with a maximum value of 2D for the differential power of the highest peak at the center (radius 0 mm). The outer optic zone 2 can be considered to begin anywhere between a radius of about 0.5 to 1.0 mm; the two zones may merge to form a continuous and relatively smooth power profile. The outer optical zone 2 comprises two sub-zones: an inner subregion having a substantially constant refractive power selected to correct distance vision; and an outer subregion with a positive power difference starting at a radius of 2.25 mm.

L2 has a similar power difference profile to that of the contact lens L1, except that the outer optic zone 2 is used entirely to correct distance vision.

L3 has a similar power difference profile to that of the contact lens L2, except for the larger diameter inner region 1 and the slower rate of change over the inner region 1.

L4 has an alternative near and far "ring" structure that includes a positive power that is more 2D positive than the power required to correct distance vision. The outer optic zone 2 starts at a radius of about 1 mm. The outer optical zone 2 comprises 3 sub-zones: a ring at the power to correct distance vision; a positive power ring having a more 2D positive power than the power required to correct distance vision between a radius of 1.5 mm to about 1.9 mm; and another ring to correct distance vision. In other embodiments, more rings may be provided that alternate between the power for distance correction and the relatively positive power. The rings of relatively positive power may have the same power as each other's rings or the power of each ring may be different.

The inner region 1 of L5 has a substantially constant optical power and is about 2.0 mm in diameter. A narrow transition zone 4 is provided for the outer optic zone 2 and the differential power between the zones is 3D.

L6 the contact lens provides a larger diameter inner zone 1 and a transition zone 4 generally located between a radius of 1.0 mm and 1.75 mm. The outer optic zone 2 has a constant power with radius.

L7 the contact lens provides an inner zone 1 having a relatively constant power that is about 1.5D more positive than the distance vision correction. The inner zone diameter is about 2 mm (1 mm radial distance from the axis). The outer optic zone 410 may be divided into an inner sub-zone between about 1 mm and 2 mm radial distance and an outer sub-zone starting at about 2 mm radius. The inner sub-zone provides a constant power for correcting distance refractive error, while the outer sub-zone adjusts the position of the peripheral image points forward by providing increasing (up to +1.5D) peripheral power.

A contact lens having an L1-like configuration may allow for possible misalignment of the pupil center with the contact lens center by still providing the proper optical power at all distances. For example, if the pupil center is off-axis by 1.0 mm, the inner optic zone 1 may not be effective in providing a suitably positive refractive power when the wearer is looking at a near subject. The outer sub-area of the outer optical zone may thus provide the necessary difference or at least reduce the difference. The positive power ring in contact lens L4 can also be treated in a similar manner to account for the asymmetry of the pupil center to the contact lens center and other embodiments of contact lenses can include 2 or more positive power sub-zones that can assist in near vision when the contact lens is not aligned with the pupil.

2.8 rotationally symmetric and asymmetric embodiments

Although the above description has focused primarily on rotationally symmetric contact lenses, other contact lens configurations may be used. For example, instead of using a generally circular inner optic zone 1 (as viewed along the center/optical axis of the contact lens), the inner optic zone 1 could be a meridian through the contact lens. The meridian may have a width of 0.5 to 3 mm, which corresponds to the diameter of the inner optical zone 1 described previously. The warp may terminate in the peripheral zone 3. In this embodiment, the outer optic zone 2 may be two meridian lines with one meridian line on each side of the inner optic zone 1. Fig. 10 shows the general structure of a contact lens 50 having the configuration of a meridian inner optical zone 51, a first meridian outer optical zone 52, a second meridian outer optical zone 53 and a peripheral zone 54. As with the contact lens structures shown in fig. 3 and 4, for a hard contact lens or corneal inlay, the peripheral zone 54 may be omitted. The power profile along the vertical semi-meridian (with reference to the orientation of the contact lens 50 shown in fig. 10) may be any of the profiles described above with reference to fig. 8.

The position of the inner optic zone 1 may be off-center if the contact lens is stabilized or otherwise formed to be oriented on the eye and still remain in place as the eye moves. This position may reflect the inward movement (toward the nose) of the pupil when viewing a near object. The movement may be about 0.5 mm.

3. Peripheral treatment profile

In certain embodiments, the contact lens 100 is designed to provide a peripheral treatment profile.

3.1A peripheral treatment Profile for myopia

One form of peripheral treatment profile for myopia is increased relative field curvature. The contact lens is designed to move the images to a focus at the peripheral retina forward so that they reach a focus at or above or in front of the retina. The use of contact lenses that can control the relative field curvature for this purpose is described in international patent publication WO 05/055891a1, which is incorporated herein in its entirety. Fig. 9, which is a reproduction of fig. 3a of WO 05/055891a1, shows the manipulation of a peripheral image by moving the focus forward in front of the retina.

3.2 example contact lenses that provide a peripheral treatment Profile

The contact lens L1 represented in fig. 8 can provide a peripheral treatment profile for myopia. As previously described, the contact lens L1 has an outer optic zone 2 that includes an outer sub-zone having a positive power difference starting at a radius of about 2.25 millimeters, in addition to the relatively positive power inner optic zone 1. The inner optical zone 1 and the outer sub-zone can both move the peripheral image forward. However, the use of the outer subregion may allow increased freedom of design to place peripheral images on or in front of the retina, as the inner subregion may be limited by the need to obtain clear vision at close distances.

The "ring" design contact lens L4 represented in fig. 8 may also provide a peripheral treatment profile for myopia. In the contact lens, the ring starting from a radius of 1.5 mm may move the peripheral image forward. In other embodiments, there may be multiple rings, each of which may move the peripheral image onto or in front of the retina. The rings may have a constant width or may vary in width, for example, the outer ring may be wider than the inner ring.

As described above, the relatively positive power sub-zone within the outer optic zone 2 can be used to address possible misalignment of the contact lens 1 with the pupil. In some embodiments, the relatively positive power sub-zones may have a power selected to correspond to the power required to clearly focus the near image. The practitioner can check whether he can also pass the peripheral image through the portion of the contact lens located on or in front of the retina. If not, the refractive power may be increased to achieve the target. Alternatively, the practitioner can design the relatively positive power sub-zone of the outer optic zone 2 with the goal of peripheral image control and substantially disregard the power required to clearly view the near object. If there are two or more relatively positive power sub-zones, the inner positive power sub-zone may have a power that takes into account near object vision requirements and the outer sub-zone may have a power designed with reference to peripheral image control (e.g., having a power difference higher than the power required to correct lag of accommodation of the eye).

A practitioner may first prepare a contact lens having a power profile of a smaller area of relatively positive refractive power and then try to use a contact lens having an increased area with relatively positive refractive power if myopic progression is still present. For example, a practitioner may first dispense a contact lens having an inner optic zone 1 wherein the diameter of the inner optic zone 1 is lower than the diameter of the pupil when viewing a near subject and the entire outer optic zone is used for distance vision. If myopia is still progressing, the practitioner may increase the area of the inner optic zone 1 to about the pupil diameter. The practitioner may then increase the outer optic zone by a relatively positive power sub-zone and may continue to increase the area of the relatively positive power sub-zone until myopia progression ceases or unacceptable distance vision is reached.

As previously described, different combinations of contact lenses can be formed, for example, by combining the contact lens L1 with one of the contact lenses 4-6 to control the location of the peripheral image.

The location and shape of the relatively positive power sub-zones may be selected to avoid creating any image priority zone that exists or extends into the outer optic zone 2. Combinations of such image priority regions with peripheral image aberrations are described in international patent publication WO 2007/082268a2, which is incorporated herein in its entirety. For example, referring to fig. 8, the contact lens may have a power profile of the general shape of L1 along most of the meridian halves, but a power profile of the general shape of L2 along one meridian half that has a width between 0.5 mm and 3 mm.

It should be understood that the invention disclosed and defined in this patent specification covers all alternative combinations of 2 or more of each such feature disclosed or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the present invention.

Claims (15)

1. A contact lens for myopia, the contact lens comprising an inner optic zone having a diameter in the range 1 to 2 mm, a transition zone and an outer optic zone surrounding the transition zone, the outer optic zone having at least one portion for correcting myopia of a wearer's eye having negative refractive power immediately adjacent the transition zone, wherein the inner optic zone is for reducing or eliminating lag of accommodation of the eye when viewing a near distance, the inner optic zone having an add power portion having an add power of between 0.5 diopters and 4 diopters which is substantially constant relative to the negative refractive power.

2. The contact lens of claim 1, wherein the outer optic zone includes at least one portion having a third power that is relatively more positive than the negative power, wherein the portion having the third power is different from the inner optic zone.

3. The contact lens of claim 2, wherein the third power is substantially equal to the power in the add power portion.

4. The contact lens of claim 2, wherein the third power is different from the power in the add power portion.

5. The contact lens of claim 4, wherein the third power is greater than the power in the add power portion.

6. The contact lens of claim 1, wherein the outer optic zone comprises at least two portions separated by a portion having a first power, said at least two portions having a power greater than a power in the addition power portion.

7. The contact lens of claim 6, wherein each of the at least two portions has the same refractive power.

8. The contact lens of claim 6, wherein each of the at least two portions has a different refractive power.

9. The contact lens of claim 8, wherein the portion having more positive power is located at a greater radial distance on the contact lens than the portion having less power.

10. A contact lens for myopia, the contact lens comprising an inner optic zone and an outer optic zone immediately surrounding the inner optic zone, the outer optic zone having at least one portion with negative refractive power, the inner optic zone for reducing or eliminating lag of accommodation of the eye when viewing at near distances, the inner optic zone comprising a central portion having an add power relative to the negative refractive power of between 1.5 diopters and 4 diopters, wherein the inner optic zone has a diameter of between 1 and 4 mm, and wherein the add power of the inner optic zone progressively decreases with increasing diameter, and wherein at the interface of the inner optic zone and outer optic zone the power of the inner optic zone is equal to the power of the outer optic zone.

11. The contact lens of claim 10, wherein the outer optic zone has a negative power that is substantially constant with radius.

12. The contact lens of claim 10, wherein the central portion has an add power of between 2.6 diopters and 4 diopters with respect to negative power.

13. A contact lens for myopia, the contact lens comprising an inner optic zone and an outer optic zone immediately surrounding the inner optic zone, the outer optic zone having at least one portion with negative refractive power and having a substantially constant negative refractive power with radius, the inner optic zone for reducing or eliminating lag of accommodation of the eye when viewing a near distance, the inner optic zone comprising a central portion having an add power relative to the negative refractive power of between 1.5 diopters and 4 diopters, wherein the inner optic zone has a diameter of between 1 and 4 mm.

14. A contact lens for myopia, the contact lens comprising an inner optic zone and an outer optic zone immediately surrounding the inner optic zone, the outer optic zone having at least one portion with negative refractive power, the inner optic zone for reducing or eliminating lag of accommodation of the eye when viewing near distances, the inner optic zone comprising a central portion having an add power relative to the negative refractive power of between 1.5 diopters and 4 diopters, wherein the inner optic zone has a diameter of between 1 and 4 millimeters.

15. The contact lens of claim 14, wherein the central portion has an add power of between 2.6 diopters and 4 diopters with respect to negative power.