Method for obtaining contact lenses with dynamically controlled sagitta and clearance
The disclosure generally describes methods, systems and products relating to the development and manufacture of scleral contact lenses. A number of dimensions for the scleral lens is generated based on control points and attendant curvature parameters. Any change to one or more of the curve parameters imparts an improved anterior and posterior surface of the scleral lens and associated thickness, while undesired modifications to control points and other curve parameters remain static inasmuch as the sagittal depth component is an input parameter of the present disclosure.
1. A method of manufacturing a scleral contact lens, comprising:
(a) providing a predicate scleral contact lens having a surface comprising a base curve segment positioned in a central portion of the lens, a dynamic curve segment peripherally surrounding the base curve segment, a limbal clearance curve segment peripherally surrounding the dynamic curve segment, and a peripheral curve segment peripherally surrounding the limbal clearance curve segment, wherein the base curve segment is defined by segment parameter components comprising a base curve sagittal component SA, a base curve radius component RA, and a base curve chord diameter component DA, the dynamic curve segment is defined by segment parameter components comprising a dynamic curve sagittal component SB, a dynamic curve radius component RB, and a dynamic curve chord diameter component DB, the limbal clearance curve segment is defined by segment parameter components comprising a limbal clearance curve sagittal component SC, a limbal clearance curve radius component RC, and a limbal clearance curve chord diameter component DC, the peripheral curve segment is defined by segment parameter components comprising a peripheral curve sagittal component SD, a peripheral curve radius component RD, and a peripheral curve chord diameter component DD, and the lens has a total sagittal clearance ST;
(b) selecting one or more control points selected from a central vault clearance, a mid-peripheral clearance, and a limbal clearance of the predicate contact lens that are to be adjusted, and one or more of such control points that are not to be adjusted, for forming the scleral contact lens to be manufactured relative to the predicate lens;
(c) altering one or more segment parameters of the predicate lens selected from the group consisting of the base curve segment, the dynamic curve segment, and the limbal clearance curve segment for adjusting each of the control points to be adjusted, in accordance with a computer implemented algorithm on computer readable media, wherein a change in one or more of the components for each of the one or more segment parameters is associated with a corresponding change in the one or more control points to be adjusted, and further wherein changes to any single segment parameter modify the contact lens at a control point to be adjusted of the one or more control points and do not modify the contact lens at control points not to be adjusted of the one or more control points, wherein (i) a change in the central vault clearance control point corresponds to changes to the dynamic curve sagittal component and to the total sagittal clearance of the lens, (ii) a change in the mid-peripheral clearance control point corresponds to changes to the dynamic curve sagittal component and to the base curve sagittal component, and (iii) a change in the limbal clearance control point corresponds to changes to the dynamic curve sagittal component and the limbal sagittal component, and wherein each of the base curve radius component, the dynamic curve radius component, and the limbal clearance curve radius component represent radii of curvature for arcs with respect to a central optical axis of the contact lens, and at least one of (iv)-(vi) is performed:
(iv) an adjustment to the total sagittal clearance of the predicate lens is specified and changes to the dynamic curve sagittal component and dynamic curve radius component of the predicate lens are calculated to effect changes in the central vault clearance control point of the lens to be manufactured, in accordance with the algorithms
ST 1=Specified
SB 1= ST 1− SA−SC
and
RB 1=SQRT((( DA/ 2){circumflex over ( )}2)+(((((( DB/ 2){circumflex over ( )}2)-(( DA/ 2){circumflex over ( )}2)+( SB 1{circumflex over ( )}2))/(2* SB 1)){circumflex over ( )}2))),
wherein ST1 is the specified adjusted total sagittal clearance, SB1 is the calculated changed dynamic curve sagittal component, and RB1 is the calculated changed dynamic curve radius component,
(v) an adjustment to the base curve radius of the predicate lens is specified and changes to the dynamic curve sagittal component, the dynamic curve radius component and the base curve sagittal component of the predicate lens are calculated to effect changes in the mid-peripheral clearance control point of the lens to be manufactured, in accordance with the algorithms
RA 2=Specified
SA 2= RA 2−sqrt( RA 2{circumflex over ( )}2−( DA/ 2){circumflex over ( )}2)
SB 2= ST−SA 2− SC
and
RB 2=SQRT((( DA/ 2){circumflex over ( )}2)+(((((( DB/ 2){circumflex over ( )}2)−(( DA/ 2){circumflex over ( )}2)+( SB 2{circumflex over ( )}2))/(2* SB 2)){circumflex over ( )}2))),
wherein RA2 is the specified adjusted base curve radius, SA2 is the calculated changed base curve sagittal component, SB2 is the calculated changed dynamic curve sagittal component, and RB2 is the calculated changed dynamic curve radius component, and
(vi) an adjustment to the limbal clearance curve radius of the predicate lens is specified and changes to the dynamic curve sagittal component, the dynamic curve radius component and the limbal clearance curve sagittal component of the predicate lens are calculated to effect changes in the limbal clearance control point of the lens to be manufactured, in accordance with the algorithms
RC 3=Specified
SC 3= RC 3−sqrt( RC 3{circumflex over ( )}2−( DC/ 2){circumflex over ( )}2− RC 3−sqrt( RC 3{circumflex over ( )}2−( DB/ 2){circumflex over ( )}2)
SB 3= ST−SA−SC 3
and
RB 3=SQRT((( DA/ 2){circumflex over ( )}2)+(((((( DB/ 2){circumflex over ( )}2)−(( DA/ 2){circumflex over ( )}2)+( SB 3{circumflex over ( )}2))/(2* SB 3)){circumflex over ( )}2))),
wherein RC3 is the specified adjusted limbal clearance curve radius, SC3 is the calculated changed limbal clearance curve sagittal component, SB3 is the calculated changed dynamic curve sagittal component, and RB3 is the calculated changed dynamic curve radius component; and
(d) forming a scleral contact lens to have a surface corresponding to the altered segment parameters.
2. The method of claim 1 , further comprising adjusting a scleral alignment angle of the lens to be manufactured relative to the predicate lens by adjusting one or more component of the peripheral curve segment of the predicate lens.
3. The method of claim 1 , wherein the sagittal component of the base curve, the dynamic curve and the limbal clearance curve comprise the total sagittal clearance for the contact lens.
4. The method of claim 2 , wherein changes to the sagittal component of the peripheral curve do not impact the total sagittal clearance.
5. The method of claim 1 , wherein an adjustment to the total sagittal clearance of the predicate lens is specified and changes to the dynamic curve sagittal component and dynamic curve radius component of the predicate lens are calculated to effect changes in the central vault clearance control point of the lens to be manufactured, in accordance with the algorithms
ST 1=Specified
SB 1= ST 1− SA−SC
and
RB 1=SQRT((( DA/ 2){circumflex over ( )}2)+(((((( DB/ 2){circumflex over ( )}2)−(( DA/ 2){circumflex over ( )}2)+( SB 1{circumflex over ( )}2))/(2* SB 1)){circumflex over ( )}2))),
wherein ST1 is the specified adjusted total sagittal clearance, SB1 is the calculated changed dynamic curve sagittal component, and RB1 is the calculated changed dynamic curve radius component.
6. The method of claim 1 , wherein an adjustment to the base curve radius is specified and changes to the dynamic curve sagittal component, the dynamic curve radius component and the base curve sagittal component of the predicate lens are calculated to effect changes in the mid-peripheral clearance control point of the lens to be manufactured, in accordance with the algorithms
RA 2=Specified
SA 2= RA 2−sqrt( RA 2{circumflex over ( )}2−( DA/ 2){circumflex over ( )}2)
SB 2= ST−SA 2− SC
and
RB 2=SQRT((( DA/ 2){circumflex over ( )}2)+(((((( DB/ 2){circumflex over ( )}2)−(( DA/ 2){circumflex over ( )}2)+( SB 2{circumflex over ( )}2))/(2* SB 2)){circumflex over ( )}2))),
wherein RA2 is the specified adjusted base curve radius, SA2 is the calculated changed base curve sagittal component, SB2 is the calculated changed dynamic curve sagittal component, and RB2 is the calculated changed dynamic curve radius component.
7. The method of claim 1 , wherein an adjustment to the limbal clearance curve radius is specified and changes to the dynamic curve sagittal component, the dynamic curve radius component and the limbal clearance curve sagittal component of the predicate lens are calculated to effect changes in the limbal clearance control point of the lens to be manufactured, in accordance with the algorithms
RC 3=Specified
SC 3= RC 3−sqrt( RC 3{circumflex over ( )}2−( DC/ 2){circumflex over ( )}2− RC 3−sqrt( RC 3{circumflex over ( )}2−( DB/ 2){circumflex over ( )}2)
SB 3= ST−SA−SC 3
and
RB 3=SQRT((( DA/ 2){circumflex over ( )}2)+(((((( DB/ 2){circumflex over ( )}2)−(( DA/ 2){circumflex over ( )}2)+( SB 3{circumflex over ( )}2))/(2* SB 3)){circumflex over ( )}2))),
wherein RC3 is the specified adjusted limbal clearance curve radius, SC3 is the calculated changed limbal clearance curve sagittal component, SB3 is the calculated changed dynamic curve sagittal component, and RB3 is the calculated changed dynamic curve radius component.
8. The method of claim 1 , wherein the base curve, dynamic curve, limbal clearance curve and peripheral curve are the segment parameters for a spherical curve.
9. The method of claim 1 , wherein the base curve, dynamic curve, limbal clearance curve and peripheral curve are the segment parameters for an aspheric curve.
10. The method of claim 9 , wherein the aspheric curve is selected from the group consisting of conical sections, polynomials, splines, straight lines, angled lines, tapered lines, polygonal curves, rectangular, square, circular, diagonal, concentric, patterned, perimetric, hexagonal, or triangular configurations, or any free form line possessing a start point, an end point, and connects two defined points in space, and/or other shapes that are congruent for use as a sagittal component.
11. The method of claim 1 , further comprising defining one or more additional segment parameter curves and/or one or more additional control points selected from the group consisting of one or more curves and/or sagittal components, wherein all the curves and/or sagittal components are defined for the contact lens other than the dynamic curve sagittal component, and wherein the dynamic curve sagittal component is calculated to achieve a desired total sagittal clearance.
12. The method of claim 1 , wherein each of the sagittal components is calculated in accordance with an algorithm defined by:
Notation
Parameter
Formula/Calculation
(SA)
Base Curve
= RA − sqrt(RA{circumflex over ( )}2 − (DA/2){circumflex over ( )}2)
(SC)
Limbal
= RC − sqrt(RC{circumflex over ( )}2 − (DC/2){circumflex over ( )}2) −
Clearance Curve
RC − sqrt(RC{circumflex over ( )}2 − (DB/2){circumflex over ( )}2)
(SD)
Peripheral Curve
= RD − sqrt(RD{circumflex over ( )}2 − DD/2){circumflex over ( )}2) −
RD − sqrt(RC{circumflex over ( )}2 − (DC/2){circumflex over ( )}2)
(SB)
Dynamic Curve
= Stotal − SD − SC − SA
Sagittal
Component
(RB)
Dynamic Curve
= SQRT(((DA/2){circumflex over ( )}2) + ((((((DB/2){circumflex over ( )}2) −
Radius
((DA/2){circumflex over ( )}2)) + (SB{circumflex over ( )}2))/(2*SB)){circumflex over ( )}2)).