WO1998034682A1

WO1998034682A1 - Methods for heating and resurfacing a substrate

Info

Publication number: WO1998034682A1
Application number: PCT/US1998/002202
Authority: WO
Inventors: Gerard M. Nolan
Original assignee: Nolan Gerard M
Priority date: 1997-02-07
Filing date: 1998-02-05
Publication date: 1998-08-13
Also published as: AU6319898A

Abstract

This invention is a method for heating only an outer exterior surface (100) of an area on a substrate. A pigmented area (120) is provided on the outer exterior surface (100) of the substrate. The pigmented area may, for example, be formed by applying a pigment to an area of interest on the outer exterior surface (100) of the substrate. The pigmented area (120) is illuminated with laser light energy for a period sufficient to heat the area of interest. During the illuminating step, substantially all of the laser light energy is absorbed by the pigmented area (120) on the outer exterior surface (100) of the substrate, and the laser light energy does not substantially penetrate into the depth of the substrate.

Description

METHODS FOR HEATING AND RESURFACING A SUBSTRATE

Field of The Invention The present invention relates generally to the field of resurfacing a substrate.

More particularly, the present invention relates to laser-based procedures for heating on an outer

exterior surface of a substrate and/or laser based procedures for resurfacing a damaged substrate.

In a particularly preferred embodiment, the present invention relates to a laser-based corneal

resurfacing procedure for treatment of recurrent corneal erosion and other abnormalities.

Background Of The Invention

Recurrent corneal erosion typically occurs in eyes that have suffered a sudden

sharp, abrading injury (e.g., fingernail, edge of paper, etc.). The superficial injury produces an

epithelial abrasion which heals rapidly, leaving no clinical evidence of damage. After an interval

varying from days to years, symptoms suddenly recur in the absence of any obvious cause. In

most instances they again subside promptly, only to recur periodically. In contrast to shearing

injuries, small and partially penetrating foreign bodies which strike the cornea directly and

become embedded in the epithelium or superficial stroma rarely produce recurrent erosions.

Some patients recall no injury and have an inherited potential for superficial degeneration of the

cornea (i.e., basement membrane disease). Repeated episodes of foreign body sensation, tearing, photophobia, and pain

describe recurrent corneal erosion which has been a most frustrating condition to treat. These

episodes mainly occur in the early morning hours upon awakening. However, these episodes can

occur at any other time of day as well. A classic example would be trauma to the cornea by a

tree branch or fingernail. When the epithelium attempts to heal over, the epithelium does not

heal well and the cells slough off. However, this can occur in a non traumatic eye as well. The

poor adhesions on the epithelium are caused by deeper adhesions in the cornea.

Objective signs of recurrent corneal erosion vary from a localized roughening of

the epithelium to a true abrasion. The less severe corneal signs resolve rapidly; and often, when

the patient is examined within hours of an acute recurrence, no abnormality is discernible. It is

recognized that the corneal epithelium is loosely attached to its basement membrane and to

Bowman's layer, both at the time of a recurrent attack and between attacks when the cornea

appears to be entirely healed.

The first and most common treatment for recurrent corneal erosion is the

consistent use of lubricating ointment and frequent instillation of artificial tear drops. Patching is

also useful. Also, because of the frequent occurrence of these episodes further methods of

treatment are used. Bandage contact lenses have been used with some success as well, but they

have been associated with infectious keratitis. Superficial epithelial keratectomy or scraping of

Bowman's layer has been somewhat effective, but these treatments have also resulted in multiple

spontaneous corneal erosions. As with anterior stromal puncture, such treatment involves

making multiple penetrations into the anterior corneal stroma in order to generate secure adhesions between the epithelium and the deeper corneal structures. Drawbacks of this

procedure include the risk of perforation, and patient apprehension that results when the patient

is approached with a needle while sitting at the slit lamp.

Yag lasers are also used as a form of treatment for recurrent corneal erosion.

With each laser application, a small bubble is formed beneath the epithelium. However, if the

application is placed too posteriorly, a small stromal lesion occurs. Conversely, if the application

is placed too anteriorly, a spark will be seen in front of the cornea.

The Excimer laser has also been shown to be effective in treating corneal

erosions. With this procedure the entire corneal surface is lasered leaving the nerves exposed

which is extremely painful for the patient. This technique is also much more expensive for the

physician to perform as well as for the patient to recompense.

It is an object of the present invention to provide an improved procedure for

treating recurrent corneal erosion that does not suffer from the drawbacks of prior treatment

methods.

In particular, it is object of the present invention to provide an effective treatment

for corneal erosion that is relatively painless for the patient, causes minimal patient

apprehension, and minimizes the risk of collateral injury to the eye as a result of the treatment.

It is a still further object of the present invention to provide an effective treatment

for recurrent corneal erosion that can be performed relatively quickly and at a reasonable cost to

the patient. It is a still further object of the present invention to provide an effective treatment

for eye abnormalities other than those relating to recurrent corneal erosion. For example, it is an

object of the present invention to provide alternative treatments for patients suffering from

swelling of the cornea or from bullous keratopathy.

It is a still further object of the present invention to provide a general method for

illuminating an epithelium layer with laser light without damaging the underlying tissue layers

beneath the epithelium. The epithelium layer treated may be on the cornea, or alternatively at

some other site on the body.

It is yet a further object of the present invention to provide a laser-based

procedure which is generally applicable outside of the field of opthamology (in other medical

and industrial applications) for resurfacing substrates.

It is yet a further object of the present invention to provide a laser-based

and industrial applications) for heating only the outer exterior surface of a substrate.

These and other objects and advantages of the invention will become more fully apparent from the description and claims which follow or may be learned by the practice of the invention.

Summary of the Invention The present invention is directed to a method for heating only an outer exterior

surface of an area on a substrate. A pigmented area is provided on the outer exterior surface of the substrate. The pigmented area may, for example, be formed by applying a pigment to an area

of interest on the outer exterior surface of the substrate. The pigmented area is illuminated with

laser light energy for a period sufficient to heat the area of interest. During the illuminating step,

substantially all of the laser light energy is absorbed by the pigmented area on the outer exterior

surface of the substrate, and the laser light energy does not substantially penetrate into the depth

of the substrate. In one embodiment, the present invention may be employed for resurfacing a

damaged area on a substrate.

Brief Description of the Drawings In order that the manner in which the above-recited and other advantages and

objects of the invention are obtained can be appreciated, a more particular description of the

invention briefly described above will be rendered by reference to a specific embodiment thereof

which is illustrated in the appended drawings. Understanding that these drawings depict only a

typical embodiment of the invention and are not therefore to be considered limiting of its scope,

the invention and the presently understood best mode thereof will be described and explained

with additional specificity and detail through the use of the accompanying drawings.

Figure 1 is a side view of a corneal surface with a plurality of abnormalities that

have marked with a pigment, in accordance with a preferred embodiment of the present

invention. Figure 2 is a front view of a corneal surface with a plurality of abnormalities that

invention.

Detailed Description of the Preferred Embodiment Reference will now be made to the drawings wherein like structures are provided

with like reference designations. It will be understood that the drawings included herewith only

provide diagrammatic representations of the presently preferred structures of the present

invention and that structures falling within the scope of the present invention may include

structures different than those shown in the drawings.

Referring now to Figures 1 and 2, there are shown side and front views,

respectively, of a corneal surface (or substrate) 100 with a plurality of abnormalities 110 that

have marked with a green pigment (or pigmented areas), in accordance with a preferred

embodiment of the present invention. In a preferred embodiment, substrate surface 100

corresponds to the epithelium or outer surface of the cornea, and abnormalities 110 correspond,

for example, to localized roughening or abrasions on the epithelium which occur in connection

with recurrent corneal erosion.

In the preferred embodiment, prior treatment of a patient having abnormalities

110, a topical anesthesia (e.g., tetracane 1%) is first placed in the patient's eye. The topical

anesthesia is preferably first dropped on a pledget which is then applied to the cornea for approximately thirty seconds. Alternatively, the topical anesthesia may be dropped directly into

the eye, after which a pledget is applied to the cornea for approximately thirty seconds. The use

of the anesthesia in combination with the pledget serves to numb the eye and make the cornea

more hydrophilic (and therefore more receptive to the pigment described below).

Thereafter, a plurality of marked corneal surfaces 120 (or pigmented areas) are

formed by applying a pigment (shown in green in Figures 1 and 2) to corneal surface 100 over

each of the corneal abnormalities 110. The pigment is preferably applied directly to the

epithelium or outer surface of the cornea by contacting either an autoclaved applicator (such as a

pin head) which has been dipped in pigment, an ink pad, a brush which has been dipped in

pigment, or a pencil or crayon which carries the pigment, to the epithelium or outer surface of the

cornea. In the embodiment shown in Figure 1, a single marked corneal surface 120 covers

several different corneal abnormalities 110. In the preferred embodiment shown in Figure 2,

each marked corneal surface 120 is centered about a corresponding corneal abnormality 110, and

the marked corneal surfaces 120 may be non-overlapping or partially overlapping. In the

embodiment shown in Figure 2, each marked corneal surface 120 preferably has an outer radius

of 0.5 to 2.5 mm measured from the center of a corneal abnoπnality 110. In an alternative

embodiment (not shown), the pigment may be applied so as to cover the entirety of surface 100.

Following application of the pigment, each marked corneal surface 120 is

illuminated with laser light for a period sufficient to heat (and thereby treat) the underlying

corneal abnormality 110. In a particularly preferred embodiment, an argon laser with a spot size

of 50-100 microns is used to perform this lasering step. When this laser is used to treat corneal abnormalities resulting from recurrent corneal erosion, the laser light is preferably applied to the

pigment over each abnormality 110 for a period of 0.1 to 0.2 seconds/spot at a power level of

200-400 milliwatts. During this lasering step, the pigment used to form the marked surfaces 120

acts as a site positioned proximate to the outer corneal surface for receiving and absorbing laser

light energy that would otherwise simply pass through the normally transparent cornea. As a

result of this pigment which acts as a receptor for the laser light, the laser light used for

illuminating the marked areas 110 is preferably transmitted to the outer surface 100 and then

only a small amount into the depth of the cornea. In a preferred embodiment, the laser light

reaches a depth corresponding to less than 5% of the thickness of the cornea. The marked areas

120 are preferably allowed to become desiccated prior to illumination of the marked areas 120

with laser light as described above.

In a particularly preferred embodiment, light emitted from a slit lamp is used to

darken the pigment on marked areas 120, thereby making the areas 120 even more receptive to

laser light during the lasering step described above. In this embodiment, a green filter may be

used to color light from the slit lamp. The colored light from the slit lamp is then aimed at the

marked areas 120 while simultaneously illuminating the marked areas with the laser light as

described above.

The pigment used for forming marked areas 120 is preferably formed from a

brilliant green ink, such as Indian ink. In a particularly preferred embodiment, the pigment used

represents a mixture of 10% methyline blue and 10% brilliant green ink. It will be understood by

those skilled in the art that other pigments (or pigment mixtures) may alternatively be used. The pigment chosen should be such that it will be receptive to laser light when applied to the outer

corneal surface. In a particularly preferred embodiment, the pigment is combined with an

antibiotic before being applied to the cornea.

The procedure described above has been used to successfully treat three patients

having recurrent corneal erosion. The procedure was painless for the three patients, caused

minimal patient apprehension, and involved virtually no risk of collateral injury to the eye.

Following application of procedure, each of the three patients healed without a patch in 1-4 days.

Although the present invention has been described in connection with a treatment

for abnormalities which occur in connection with recurrent corneal erosion, it will be understood

by those skilled in the art that the procedure of the present invention may be used to treat or

repair corneal abnormalities or abrasions resulting from other conditions such as primary

basement membrane disease or bullous keratopathy, or as an alternative treatment for patients

requiring a corneal transplant. It is also believed that the method of the present invention may be

applied to treat abnormalities on epithelium layers at other sites on the body beyond the cornea,

without damaging the underlying tissue layers beneath the epithelium.

Finally, it is believed that the present invention may be applied generally outside

of the medical field and, in particular, in industrial applications for heating and/or resurfacing

damaged areas on a substrate. In such applications, any heat producing laser (including, e *., an

argon or diode laser) may be used in connection with the process described herein for heating

and/or resurfacing an area of interest on the substrate. Moreover, in industrial applications where

the substrate already has pigment on its outer surface, the present invention may be employed without the need for application of an additional external pigment prior to illumination of the

substrate surface with the laser light energy. It is believed that the method of the present

invention could advantageously be used, for example, to clean and/or sterilize (using heat) the

exterior surfaces of various substrates.

Furthermore, it is to be understood that although the present invention has been

described with reference to a preferred embodiment, various modifications, known to those

skilled in the art, may be made to the structures and process steps presented herein without

departing from the invention as recited in the several claims appended hereto.

Claims

What is claimed is:

1. A method for heating only an outer exterior surface of an area on a substrate,

comprising the steps of:

(A) providing a pigmented area on said outer exterior surface of said substrate; and

(B) illuminating said pigmented area with laser light energy for a period sufficient to heat

said pigmented area;

wherein substantially all of said laser light energy is absorbed by said pigmented area on

said outer exterior surface of said substrate.

2. The method of claim 1, wherein step (A) comprises the step of forming said

pigmented area by applying a pigment to said area on said outer exterior surface of said substrate.

3. The method of claim 2, wherein said pigmented area has an outer radius of 0.5 to 2.5

mm.

4. The method of claim 2, wherein step (A) comprises forming a plurality of pigmented

areas by applying said pigment over a plurality of areas on said outer exterior surface of said

substrate, and step (B) comprises illuminating each of said pigmented areas with laser light for a

period sufficient to heat each of said pigmented areas.

5. The method of claim 4, wherein said pigmented areas are partially-overlapping.

6. The method of claim 4, wherein said pigmented areas are non-overlapping.

7. The method of claim 2, wherein said applying step further comprises applying said

pigment over an entirety of an outer surface of said substrate.

8. The method of claim 1, wherein during step (B) said laser light is transmitted through

an outer surface of said substrate to a depth in said substrate, said depth being limited to less than

5% of a thickness of said substrate.

9. The method of claim 1, wherein step (B) further comprises illuminating said

pigmented area with laser light from an argon laser.

10. The method of claim 9, wherein said argon laser has a spot size of 50 to 100 microns,

and said period ranges from 0.1 to 0.2 seconds/spot.

11. The method of claim 1 , wherein step (B) further comprises illuminating said

pigmented area with laser light from a diode laser. '

12. The method of claim 2, wherein said applying step further comprises contacting an

outer surface of said substrate with a pin-head sized applicator carrying said pigment in order to

apply said pigment to said outer surface of said substrate.

13. The method of claim 2, wherein said applying step further comprises contacting an

outer surface of said substrate with an ink pad in order to apply said pigment to said outer surface

of said substrate.

14. The method of claim 2, wherein said applying step further comprises using a brush

for applying said pigment to an outer surface of said substrate.

15. The method of claim 2, wherein said applying step further comprises using a pencil

for applying said pigment to an outer surface of said substrate.

16. The method of claim 2, wherein said applying step further comprises using a crayon

for applying said pigment to an outer surface of said substrate.

17. The method of claim 1, wherein said pigment is formed from Indian ink.

18. The method of claim 1, wherein said pigment is formed from brilliant green ink.

19. The method of claim 18, wherein said pigment is formed from a mixture of

methyline blue and brilliant green ink.

20. The method of claim 19, wherein said pigment is formed from a mixture of 10%

methyline blue and 10% brilliant green ink.

21. The method of claim 2, further comprising the step of, prior to step (B), allowing said

pigmented area to be become desiccated.

22. The method of claim 1, further comprising illuminating said pigmented area with

filtered light while simultaneously illuminating said pigmented area with said laser light, wherein

said filtered light and said laser light travel along different optical paths before reaching said

pigmented area.

23. A method for treating a corneal abnormality, comprising the steps of:

(A) forming a marked corneal surface by applying a pigment over said corneal

abnormality; and

(B) illuminating said marked corneal surface with laser light for a period sufficient to

treat said corneal abnormality.

24. The method of claim 23, wherein said applying step further comprises applying said

pigment to an outer surface of a cornea.

25. The method of claim 24, wherein said marked corneal surface is centered about said

corneal abnormality.

26. The method of claim 25, wherein said marked corneal surface has an outer radius of

0.5 to 2.5 mm from a center of said corneal abnormality.

27. The method of claim 25, wherein step (A) comprises forming a plurality of marked

corneal surfaces by applying said pigment over a plurality of corneal abnormalities, step (B)

comprises illuminating each of said marked corneal surfaces with laser light for a period

sufficient to treat each of said corneal abnormalities, and wherein each of said marked corneal

surfaces is centered about a corresponding one of said corneal abnormalities.

28. The method of claim 27, wherein said marked corneal surfaces are partially-

overlapping.

29. The method of claim 27, wherein said marked corneal surfaces are non-overlapping.

30. The method of claim 24, wherein said applying step further comprises applying said

pigment over an entirety of said outer surface of said cornea.

31. The method of claim 24, wherein during step (B) said laser light is transmitted

through said outer surface to a depth in said cornea, Said depth being limited to less than 5% of a

thickness of said cornea.

32. The method of claim 23, wherein step (B) further comprises illuminating said

marked corneal surface with laser light from a coherent argon laser.

33. The method of claim 32, wherein said coherent argon laser has a spot size of 50 to

100 microns, and said period ranges from 0.1 to 0.2 seconds/spot.

34. The method of claim 24, wherein said applying step further comprises contacting

said outer surface of said cornea with a pin-head sized applicator carrying said pigment in order

to apply said pigment to said outer surface of said cornea.

35. The method of claim 24, wherein said applying step further comprises contacting

said outer surface of said cornea with an ink pad in order to apply said pigment to said outer

surface of said cornea.

36. The method of claim 24, wherein said applying step further comprises using a brush

for applying said pigment to said outer surface of said cornea.

37. The method of claim 24, wherein said applying step further comprises using a pencil

for applying said pigment to said outer surface of said cornea.

38. The method of claim 24, wherein said applying step further comprises using a crayon

for applying said pigment to said outer surface of said cornea.

39. The method of claim 23, wherein said pigment is formed from Indian ink.

40. The method of claim 23, wherein said pigment is formed from brilliant green ink.

41. The method of claim 40, wherein said pigment is formed from a mixture of

methyline blue and brilliant green ink.

42. The method of claim 41, wherein said pigment is formed from a mixture of 10%

methyline blue and 10% brilliant green ink.

43. The method of claim 23, wherein said pigment is mixed with an antibiotic before

being applied over said corneal abnormality in step (A).

44. The method of claim 23, further comprising the step of, prior to step (A), applying a

topical anesthesia to said outer surface of said cornea.

45. The method of claim 44, wherein said topical anesthesia is applied using a pledget.

46. The method of claim 45, wherein said outer surface of said cornea is hydrophilic

after said topical anesthesia is applied using said pledget.

47. The method of claim 23, further comprising the step of, prior to step (B), allowing

said marked corneal surface to be become desiccated.

48. The method of claim 23, further comprising illuminating said marked corneal surface

with filtered light while simultaneously illuminating said marked corneal surface with said laser

light, wherein said filtered light and said laser light travel along different optical paths before

reaching said marked corneal surface.

49. The method of claim 23, wherein said corneal abnormality corresponds to an

abnormality resulting from recurrent corneal erosion.