Therapeutic Contact lenses

contact lens

1. Therapeutic Contact Lens Manoj Aryal B . Optometry Institute Of M edicine, Maharajgunj Medical c ampus

2. Presentation layout Introduction Classification of TCL types Essentials of fitting a TCL The aims of therapeutic contact lens wear Complications associated with therapeutic contact lenses wear Aftercare Conclusions Therapeutic contact lens (TLC)

3. Introduction Definition: The term “therapeutic” is derived from the Greek word “therapeuein” meaning to take care of, or to heal . M ainly fitted with the aim of attempting to maintain or restore the integrity of ocular tissues.

4. The five main aims of therapeutic contact lenses are : 1 . Relief of ocular pain; 2. Promotion of corneal healing; 3. Mechanical protection and support; 4 . Maintenance of corneal epithelial hydration; 5. Drug delivery

5. Classification: TCL Silicone rubber and silicone hydrogels (38 %); Hard (PMMA) and gas permeable scleral lenses; Hard scleral rings ; Hydrogel soft lenses Low water content ( 38%-45%); Mid-water content (45 %-55%); High water content (67 %-80%); Collagen shields

6. Silicon Hydrogel They offer theoretical advantage of oxygen transmissibility and is more suitable for overnight wear The disadvantage includes the increased rigidity, poor surface wettability, and limited parameters

7. For painful eyes with irregular corneas, the more soft or flexible the lens the more likely an acceptable and comfortable fit will be achieved Lens deposition may be a problem especially mucin balls The increased rigidity may also be expected to increase the risk of CL related papillary reaction, conjunctivitis and SEAL

8. Applications : Main application is for wound healing (persistent epithelial defect, corneal ulceration etc .). They are used for the apposition of wound edges and pain relief. Corneal ulceration Persistent epithelial defect

9. However, the applications may be constrained by the limited range of total diameters and limited choice of BOZR Some lenses are not available in Plano power, some patients with good visual acuity may not tolerate the change in induced ametropia, such as RCE patients with a VA of 6/5

10. Silicon rubber Silicone rubber lenses are difficult to fit . The total diameter must closely correspond to the corneal diameter Some movement and tear exchange is essential and uniform edge clearance and central corneal alignment is desirable but rarely achieved.

11. The lenses often steepen unpredictably and can bind to the cornea . Thus the fit should be checked immediately following insertion, then again after a few minutes, and after one to two hours and also the following day. Lens removal can be difficult, especially on a dry eye

12. Properties and application: H as a high oxygen transmissibility (Dk 200-400), and absorbs no water so lens parameters are independent of hydration, tear quality or exposure. The lenses are also robust and flexible but they must be coated to improve surface wetting. Until recently they were the first choice for the maintenance of corneal hydration, e.g. Sjögrens syndrome, exposure and neurotropic keratitis.

13. They also offered protection of the ocular surface from eyelashes, keratin, exposure, and glue. In the presence of a severe dry eye silicone rubber lenses improved the ocular environment to assist wound healing of a corneal perforation and to promote re-epithelialization of a persistent epithelial defect. The lens was also used to provide pain relief for ocular surface disease

14. Scleral lenses With a typical diameter of 23mm,RGP scleral lenses offer protection of both the cornea and the bulbar conjunctiva. If the lens is fitted to give corneal and limbal clearance the lens will maintain a tear reservoir while protecting the cornea from the shearing forces of the eyelids . Thus Sjögrens, cicatrizing conjunctivitis and corneal exposure are typical indications.

15. Therapeutic Use Irregular or abnormal corneal topography High astigmatism Keratoconus or other primary corneal ectasia Corneal transplant Traumatized eye Post-refractive surgery

16. Contd… High refractive errors Centration difficulties with high-power corneal lenses. Intolerance to corneal or hydrogel lens wear in myopia or hypermetropia Iris encapsulation I ntractable diplopia. Cosmetic shells. Unsightly blind eyes. Aniridia. Microphthalmos.

17. Therapeutic or protective applications Corneal hydration in serious dry eye conditions such as Stevens Johnson syndrome and cicatricising conjunctivitis, ocular pemphigoid Prevention of tear film evaporation with poor lid closure or lid absence Corneal protection against trichiasis or lid margin keratinisation Preventing mucus filaments adhering to the cornea Ptosis

18. Other indications include : Maintenance of fornices Ptosis prop Promotion of epithelial healing in the presence of a severe dry eye, and Rarely pain relief, neurotropic keratitis and persistent epithelial defects

19. Therapeutic use of Scleral Lens Excessive Protrusion in keratoconus & Scleral Lens Wear

20. Therapeutic use of Scleral Lens Entropion Ptosis Correction

21. Limbal diameter RGP lenses Applications and properties : RGP lens that covers the cornea has the advantage of: O ffering complete corneal protection M aintaining a corneal tear reservoir and C an be used with topical medication .

22. Also lenses with a high oxygen transmissibility are available W hich flex less than silicone rubber, so are less likely to bind . The lenses can be used in severe dry eye, corneal exposure, trichiasis, and; in these cases they assist with wound healing and may even offer pain relief

23. Collagen shields M ay be used to promote re-epithelialization. They mould to the shape of the cornea and dissolve over time so they have been advocated for managing epithelial defects. However , they are uncomfortable , give poor vision, the cornea cannot be examined through the shield, the dissolution rate is variable and unpredictable , and finally they are difficult to remove .

24. Lens type Primary indications 1)Hydrogels Pain relief a) Thin mid water content with high bound water First choice incl.- irregular corneas, mild to moderate dry eyes b)Steep hydrogel lenses For step corneas c) Large hydrogel lenses For limbal and scleral defects and buphthalmos 2) Silicon hydrogels For wound healing, apposition of wound edges, short term mechanical protection 3) Rigid gas permeable Corneal protection, maintenance of corneal hydration, promotion of epithelial healing 4) Scleral Mechanical protection of ocular surface, maintain corneal hydration

25. Essentials of Fitting a TCL Slit lamp The presence of an anterior segment disorder commonly renders the patient photophobic so the ability to diffuse light and/or reduce the intensity of the slit lamp beam is of particular value in minimizing patient discomfort

26. Keratometry Generally not necessary for adequate fitting of soft bandage lenses. However, it may have a value in monitoring the progression of some conditions, for example, keratoconus and progressive corneal dystrophies In the presence of gross corneal distortion and the absence of any corneal graft, measuring K-readings of the fellow non-diseased eye can provide a useful guide.

27. Lens selection A thicker lens may be more desirable when the function is to act as a splint (as in descemetocele) or to cover an irregular corneal surface Thicker lenses may also be desirable in some cases of tear film instability to support a more stable tear structure. A thinner lens is more appropriate in cases of epithelial disruption (for example, recurrent erosion)

28. Lens Fitting Ideally, a well fitting bandage lens should provide full corneal coverage, be centered, with adequate movement (>0.25mm with each blink) to allow clearance of debris. It is important for the lens fit to be stable, avoiding excessive movement, as this can cause discomfort or further epithelial disruption. Stability can be enhanced by increasing the lens total diameter

29. Parameter range The majority of ‘bandage lenses’ used are Plano or near Plano prescription. In most circumstances, soft lenses of standard total diameters 14.0mm to 14.5mm will suffice. Larger diameter lenses (15mm to 20mm) may be required where the specific function is to protect the limbus or prevent wound leakage at suture or incision sites Larger diameter lenses require flatter back optic zone radii to achieve the desired fit.

30. Lens stability Both a stable fit and minimal dehydration are desirable. In cases of irregular corneas, such as advanced cases of keratoconus or post surgery, a stable fit may not be achievable with a single lens material. Piggyback or hybrid lenses can offer success in cases when acceptable centration cannot be achieved with a an RGP alone.

31. Piggy-back systems Helpful when RGP lens is intolerable due to staining and patient reluctant to surgery where a rigid corneal lens is worn over a soft lens Soft lens Extra limbal negative or Plano soft lens ( mod. To high Dk) RGP lens (TD – 9.0 & 10.0 mm ) Disadvantages RGP rides low with little or no movement Localized hypoxia & neovascularization Difficult to handle/maintain two types of lenses

32. Avoid the use of topical anesthetics as this may mask the pain associated with a poor fitting lens . The lens fit should be assessed after approximately 20 minutes and ideally again after approximately 60 minutes (owing to lens dehydration effects ). Peripheral lens fit is also very important as e.g. flared lens edges may gives rise to discomfort etc . A well fitting TCL should have good corneal coverage with appropriate mobility

33. Suggestions for improving corneal coverage, centration and stability First Last Poor corneal coverage Increase total diameter Steepen BOZR Excess lens movement Reduce thickness Steepen radius Increase diameter Lens too tight Reduce thickness Flatten radius Decrease diameter Irregular ocular surface Low modulus of elasticity Thin lens Dry eye/ exposure High bound water Reduce water content Non-ionic Increase thickness Restricted Fornices Reduced diameter, typically 13.00mm

34. Aims of therapeutic contact lens wear The cause of ocular pain includes: E xposed or compressed nerve endings in recurrent corneal erosion, Thygeson's disease, and bullous keratopathy Tension from the eyelid on mucous-epithelial tags in filamentary keratitis and superior limbic keratitis . Mechanism: lens protects the cornea from the shearing force of the eyelid during blink . Aim 1: Relief of pain

35. A . Bullous K eratopathy This condition of chronic edema of the cornea can be extremely painful. M ain aim of the therapeutic lens: alleviate the symptoms of pain, epiphora, photophobia and blepharospasm and also attempt to reduce the chronic edema Endothelial cell malfunction is frequently a common factor

36. Malfunction of endothelium may occur as the result of a dystrophic process such as Fuch’s dystrophy Fuch’s dystrophy usually begins with guttation of the corneal endothelium It is bilateral but usually asymmetrical The guttation are initially seen in the central cornea and spread peripherally. Slight stromal edema occurs and is eventually followed by epithelial edema and bullous keratopathy

37. S cenarios where TCL use could be considered in Bullous keratopathy 1. In a patient with a painful eye with no visual potential : & 2. In a patient who is not fit for graft surgery. Action This is best fitted with a TCL as soon as possible. Lens movement should be minimized and I s best achieved by the employment of a large, hydrogel lens with high water content to maintain the maximum oxygen permeability for continuous wear.

38. 3.As a temporary measure where a patient is going to have a penetrating keratoplasty at some future date . Action: A thin high water content TCL is indicated due to the reduced risk of producing corneal vascularization.

39. B . Filamentary keratitis Action: In severe cases a high water content TCL could be considered where the main function is to act as a pressure bandage thus relieving pain and foreign body sensation. Severe filamentary keratitis in a mucus sheet in a patient with severe dry eye due to Sjögren's syndrome

40. C. THYGESON’S SUPERFICIAL PUNCTATE KERATITIS It consists of recurrent episodes of fine superficial greywhite punctate corneal opacities of presumed viral etiology. The corneal opacities distort the epithelial surface and may even reduce visual acuity .

41. Action: In severe cases a high water content TCL could be considered where the main function is to act as a pressure bandage thus relieving pain and foreign body sensation.

42. D . Superior limbic keratoconjunctivitis Action: TCLs are very effective in alleviating both signs and symptoms of the disease. Consider a relatively large TD soft TCL

43. Aim 2 : Promotion of epithelial healing A. RECURRENT CORNEAL EROSION: Anterior membrane dystrophies Action: TCL used on an extended wear basis for 2, 3 or even 6 months. Ultra-thin TCLs are contraindicated due to possible buckling or wrinkling of the lens with lid movement, thus producing an ineffective corneal splint action. A thick, high water content extended wear lens is preferred. “Disposable” lenses are recommended.

44. B. Traumatic corneal abrasions: Abrasions over 4mm may benefit from the use of TCLs Action : The use of disposable lenses is indicated, particularly in the treatment of corneal erosions with good success

45. C . Persistent corneal epithelial defect C ornea is more vulnerable to infection and therefore PED is associated with a High rate of ulceration and perforation Action : TCLs (e.g. “disposables”) can provide mechanical protection from the lids. Collagen shields hydrated in acidic fibroblast growth factor have been shown to promote epithelial wound healing in such cases.

46. D. Chemical injuries Chemical injuries may suffer severe stromal ulceration due to the collagenolytic activity unleashed . The presence of a TCL may inhibit the passage of certain proteolytic enzymes present in the tear fluid to the stroma, thus preventing the progressive ulcerative process following chemical injuries

47. Action : A chemical burn to the eye is often associated with chemosis as well as the epithelial damage. Therefore : - A small total diameter TCL is the lens of first choice (TD~12.5mm ). If the lids are involved, a scleral lens may be better

48. E . Postoperative epithelial disorders: Many ophthalmic surgical procedures can result in temporary corneal epithelial defects. These include: Vitrectomy Post penetrating keratoplasty in the early post operative period Epikeratoplasty Kerato-refractive procedures e.g. PRK, LASIK Cataract extraction

49. Action : Soft and collagen TCLs may be utilized in order to minimize post surgical epithelial trauma, provide a stable healing environment and promote rapid healing F. Penetrating keratoplasty A silicon rubber TCL may be used to reform the anterior chamber

50. Aim 3 :Mechanical protection and support A. CORNEAL LACERATION Action : With small perforations (less than 2mm) without tissue loss, structural support may be achieved and the integrity of the eye maintained, by the utilization of a TCL Perforations close to the limbus and those in vascularized areas respond most favorably to the application of TCLs .

51. Partial thickness corneal lacerations involving stroma, with the wound edges well a positioned can be treated with a TCL. A small perforation near the visual axis may heal with less resultant astigmatism if a TCL rather than a suture is used . A thin low water content soft lens would be the lens of first choice

52. B . TRABECULECTOMY Large (total diameter 20.5mm ), high water content TCLs can be fitted to press over the leaking bleb C . CORNEAL THINNING Fit a hydrophilic TCL to act as a corneal splint, which can retard or even stop the rate of thinning and hence prevent perforation. As this often occurs in dry eyes, silicone rubber lenses may be better

53. D . PROTECTION OF CORNEA TCLs and particularly scleral lenses are very useful in providing protection and comfort in Trigeminal (5th) nerve palsy, Facial (7th) nerve palsy . Consider a pre-formed scleral lens. Other situations include: - Lid deformities with eye exposure Entropion, Trichiasis Scarred lids.

54. Aim 4: Maintenance of corneal hydration A. CICATRIZING CONJUNCTIVAL DISEASE Stevens-Johnson Syndrome Ocular pemphigoid Chemical burn Trachoma Pseudo-membranous and membranous conjunctivitis Atopic keratoconjunctivitis Dry eyes

55. I) Steven’s Johnson syndrome: B/L conjunctivitis is a feature Which usually lead to scarring of the conjunctivas Severe irreversible changes such as scarring, keratoconjunctivitis sicca, symblepharon, entropion and trichiasis may occurs

56. Treatment with scleral lens or ring is usually helpful A scleral lens does also retain a tear layer in front of the cornea and this helps in reducing corneal keratinization and provides better vision by negating the optical effects of corneal irregularities It is desirable to use a very large(15-20mm), low or medium water content lens to prevent adhesion forming or re-forming

57. Thin lens : tend to distort and wrinkle Better to use thicker more rigid lens and Low water content lenses: tend to become coated too quickly to deposits Use of medium water content lenses(55%) relatively thick lens seem optimal Large sophisticated multi-curved flexible silicon lenses : lens of choice

58. II) THE DRY EYE: In marginal to severely dry eyes hydrophilic TCLs are not recommended. Silicone rubber lenses may be considered

59. III) Ocular pemphigoid Therapeutic contact lens indicated: To protect the cornea against the action of ingrowing lashes and malposition of lids Thin lenses are to be avoided and thicker lenses are preferred Lens must be large enough

60. IV) Trachoma In earliest stage Presence of soft immature follicles in the upper tarsal conjunctiva A punctate keratitis Early superior corneal pannus In late stage Cicatrization of lids Symblepharon Trichiasis And distortion of lids Therapeutic contact lenses can be used to separate inflamed tissue to prevent symblepharon and to avoid the effects of ingrowing lashes

61. Aim 5: Drug delivery Hydrogel TCLs alter the pharmacokinetics and effectiveness of topically applied drugs. Hydrogel lenses soaked in medication and then placed on the eye generally give very high ocular levels of medication that diminish with time which are superior to frequent topical application of drops alone . Medication impregnated lenses are appropriate for short-term use when corneal protection and therapeutic levels of specific medications are desired.

62. Other conditions requiring therapeutic contact lenses Reducing the effect of aqueous leaks Improvement of vision Protection of cornea during tonometry Maintenance of conjunctival formices Ortoptic uses Control of refractive errors

63. Reducing the effect of aqueous leaks Perforation in the anterior segment which lead to loss of aqueous fluid can often be controlled by a tightly fitting soft contact lens which partially seals the perforation, whether it be created by trauma or surgery .

64. Improvement of vision RGP and scleral lenses can provide a regular anterior refracting surface and improve the visual acuity considerably. In cases of extreme corneal sensitivity or irregularity, where contact of the cornea with a hard surface is inadvisable, a rigid lens can be fitted on top of a soft lens to provide the required, regular refractive surface.

65. Maintenance of conjunctival formices M ay occur in several scarring disease of mucosa, for e.g. erythema multiforme, ocular pemphigoid and chemical burns. Although a scleral lens is commonly used to separate the tissue surfaces, a very large and reasonably soft contact lens can be used for same purpose.

66. Ptosis props If the eyelid occludes the visual axis, a ptosis prop may be required. A modified scleral lens may be successful depending on the force closing the eyelid . Indications include: O cular myopathy, M yasthenia gravis, eyelid trauma and N eurological problems (e.g. Third nerve palsy).

67. Neuroparalytic and neurotropic conditions Signs: Loss of corneal sensitivity Epithelium becomes dry and areas of necrosis eventually occur Daily wear of large medium water content soft lens is better I f extended wear is preferred, then 2 or more lenses should be alternated daily in order to keep the lenses clean

68. Orthoptic uses A contact lens may be used as a cosmetic occlude in cases of intractable binocular diplopia Any type of contact lens may be used Usually, complete occlusion can only be achieved by having an opaque iris pattern and opaque pupil

69. In squint treatment, contact lens occlude have been used before the better eye to assist in eliminating diplopia Partial occlusion with contact lenses has also been used in the treatment of suppression The fitting of anisometropic amblyopes with contact lenses has brought about some dramatic improvements in the visual acuity and assisted in the orthotic treatment of squints in such cases

70. Orthokeratology Non surgical clinical technique that uses specially designed and fitted Rigid CLs(flat fit) To reshape the corneal contour For temporal modification and elimination or reduce refractive errors

71. Orthokeratology Principles: Corneal Shape Change Compression/redistribution of fluids/cells from the center to periphery Thinner central corneal epithelium – Positive pressure from a flat central lens curve Thicker mid-peripheral corneal epithelium – Negative pressure from tear pool under steep 2nd (reverse) curve Control of refractive errors

72. Advantages To be free of both CLs and spectacle all day Ideal for sportsman, swimmers or those who work in dusty or dirty environment Ideal for contact lens intolerant patients Disadvantages Patient needs meticulous follow ups Retainer lens wear is essential throughout the life The degree of success is high but cannot always be guaranteed

73. Patient Selection Good Candidates Moderate to low level myopes (-1.00D to -5.00D) <1.50D astigmatism Corneal diameters greater than 11.00mm Soft lens / spectacle wearers Poor Candidates H igh level myopia/astigmatism Against the rule astigmatism > 0.75D Current GP / past PMMA lens wearers

74. As an aid to defective color vision A red contact lens, of peak transmission 595nm worn in one eye only has been recommended by La Bissorniere (1974). Known as the X-Chrome lens , during binocular viewing it gives rise to a different perception of hues, altering their saturation or brightness , and the wearer learns to relate that appearance to a particular color name.

75. Therapeutic contact lens selection: examples CHOICE FIRST LAST Pain relief Hydrogel Silicon hydrogel Scleral Limbal RGP Epithelial healing Silicon hydrogel Hydrogel Scleral Limbal RGP Perforation Silicon hydrogel Hydrogel Scleral Limbal RGP Sensitive type Hydrogel Silicon hydrogel Scleral Limbal RGP Ease of fit Hydrogel Silicon hydrogel Limbal RGP scleral

76. SEVERITY MILD SEVERE Exposure Hydrogel Silicon hydrogel Limbal RGP Scleral Dry eyes H ydrogel Silicon hydrogel Limbal RGP Scleral Corneal protection Hydrogel Silicon hydrogel Limbal RGP Scleral Irregular ocular surfaces Hydrogel Silicon hydrogel Limbal RGP Scleral

77. I ndications for therapeutic lens wear

78. Complications Factors associated with complications in therapeutic lens wear Patient related Severity of ocular pathology Concurrent dry eye Concurrent topical corticosteroids Poor compliance – ocular hygiene – general hygiene Poor general health Lack of motivation Absence of corer Lens related Hypoxia – low water content – thick lens Deposition Mechanical insult – poor fit

79. Management of complications The patient should be informed of the benefits and risks of therapeutic lens wear In view of potential increased risk of microbial keratitis, prescribe antibiotics for prophylactic purposes, especially in the presence of an epithelial defect Patients often benefit from the use of non-preserved wetting drops to insert upon waking .

80. The use of medication in ointment form is not usually appropriate because of the effect on lens wettability and vision Lens-related effects can be minimized by the practitioner choosing the best lens type for an individual patient. Maximizing oxygen transmissibility will limit hypoxic effects

81. Frequent lens replacement is an effective way of management of deposits Lid hygiene procedures should be explained and demonstrated, and For those patients wearing therapeutic lenses on a daily wear basis the importance of hand washing, prior to touching the eye or lenses should be reviewed at each aftercare visit

82. Topical medication and contact lens Hydrogel Silicon hydrogel Silicon rubber Rigid: corneal Rigid: scleral Fluorescein Ointments ? V.A. V.A. V.A. V.A. Preserved Rx Short term Short term Un- preserves Rx

83. Aftercare Practitioners should be aware the lens fit may change as the therapy progresses. Visual acuity should be measured and recorded at each visit P atient is well instructed on both the need for good hygiene and what action to take if a problem arises

84. It is usual for a bandage lens to be worn overnight, hence the lens fit and ocular status should be reviewed again after the first night of wear . In contrast, in cases such as bullous keratopathy where the lens provides pain relief, regular lens removal and replacement is desired . In such cases the use of disposable lenses is beneficial . The silicone hydrogel lens has proved very successful in the management of this group of patients

85. C onclusions Contact lens fitting for therapeutic purposes is not a part of mainstream practice, practitioners should be familiar with its practice and the techniques involved to enable them to provide advice and appropriate levels of aftercare. The objective is rarely to achieve an optimal visual result, rather to protect or assist in the healing process of the compromised cornea

86. The same high level of care must be taken in all aspects of the contact lens fitting and aftercare process . Close collaboration with the medical management of the condition is required . Therapeutic contact lens practice can be challenging, but often rewarding as it can lead to dramatic improvements for the patient in reducing discomfort and aiding the healing process

87. References Anthony J Phillips and Janet Stone CONTACT LENSEs Internet Search

88. THANK YOU