Therapeutic Applications

Introduction

The concept of a protective eye bandage originated in the first-century ad when Celsus reportedly applied honey-soaked linen to the site of a pterygium removal to prevent symblepharon development ( ). The therapeutic use of contact lenses goes beyond visual improvement in irregular and distorted corneas or correction of refractive errors. The term ‘therapeutic contact lens’ has become synonymous, for many, with a soft plano ‘bandage’ lens; however, the therapeutic use of contact lenses is much more extensive.

Definitions

Recently, CLEAR proposed a clinical definition of therapeutic contact lenses, differentiating them from rehabilitative contact lenses. Both contact lens categories, therapeutic and rehabilitative, are considered medical contact lenses ( ):

Medical Contact Lenses are any type of contact lens that is worn for the primary purpose of treating an underlying disease state or complicated refractive status. Medical contact lenses may or may not correct refractive error. Medical contact lenses are prescribed for reasons other than the cosmetic purpose of eliminating the need for spectacles. There is no universally accepted definition for medical contact lenses, but some payers do set requirements as to condition or diagnosis (e.g., cornea ectasia, unilateral aphakia) or threshold value for refractive error (e.g. high myopia) before a coverage or reimbursement is granted. Requirements and definitions vary from nation to nation and by payer .

Medical contact lenses are subdivided into two different clinical categories:

Therapeutic or Bandage Contact Lenses are contact lenses that are used for the treatment of ocular discomfort or to support the cornea during healing after surgery or when the cornea is being treated for an underlying disease state or to protect the cornea from the environment or mechanical interaction with the lids .
Rehabilitative Contact Lenses are CLs that are prescribed for conditions that prevent a patient from achieving adequate visual function with spectacles because of high, irregular, or asymmetric refractive error .

Lens Types

It should be recalled that all types of contact lens have therapeutic uses.

Soft Hydrogel and Silicone Hydrogel Lenses

When considering the fitting of a bandage lens, it is necessary to define or predict its probable pattern of use. The relevant considerations are:

whether extended wear is necessary,
whether the patient (or, failing the patient, a relative or friend) can be taught to handle or at least to remove, the lens,
the likely duration of therapeutic lens management,
whether the patient lives within practical travelling distance of the clinic or hospital,
whether the necessary topical medications are available nonpreserved and
whether the risks of hypoxia, mechanical trauma and infection are outweighed by the perceived benefits of therapeutic lens wear.

In the past, clinics may have kept sets of bandage lenses – custom made from high-water-content materials – in various radii and diameters. These were superseded by commercially available frequent-replacement hydrogel lenses ( ), which in turn, have largely been replaced by lenses in silicone hydrogel materials.

Silicone hydrogel lenses have an important therapeutic role because of their very high gas permeability, which minimizes the induced hypoxic and hypercapnic stress ( ). Their relatively low water content is an advantage where hydration of the lens by the tear film is problematic, as occurs in aqueous tear deficiency. Soft bandage contact lenses have demonstrated positive results in managing dry eye in terms of comfort and visual acuity improvement since the 1970s ( ). Subsequent studies have confirmed these results. Comparison studies have been carried out between hydrogel and silicone hydrogel lenses in some therapeutic applications. For example, silicone hydrogel lenses have been shown to be a safe and effective alternative to conventional contact lenses for the treatment of bullous keratopathy ( ).

Silicone hydrogel lenses are widely used following photorefractive keratectomy and laser-assisted subepithelial keratomileusis (LASEK) ( Chapter 29 ). In one study, the corneal epithelial status was statistically better in the eyes with a silicone hydrogel bandage contact lens 5 days after surgery compared with when a hydrogel lens was worn ( ). Studies evaluating the relative performance of different silicone hydrogel lenses have shown little difference between them, except in terms of comfort ( ).

When fitting any soft lens, it is important for the lens to overlay all areas requiring cover and to aim for a minimal amount of movement on blinking. There must be no compression of the limbal vessels ( Fig. 28.1 ).

Fig. 28.1, A large (20.5 mm diameter) soft bandage lens fitted to relieve pain in a 27-year-old man with Marfan’s syndrome following ethylenediamine tetraacetic acid treatment. After numerous eye operations (cataract extraction, ablatio retinae, vitreous oil procedures), a painful band keratopathy formed and a trophic ulcer was present.

Corneal Lenses

Corneal lenses are frequently used for a combination of optical and therapeutic indications. Though they are usually smaller in diameter than the cornea, they may provide enough coverage to protect the cornea from abnormal lashes, keratinized lid margins and other hostile factors ( Fig. 28.2 ). Sometimes lenses of larger diameters are used ( Fig. 28.3 ).

Fig. 28.2, Rigid lens fitted to a highly myopic (−10.00 D) buphthalmic eye of a 29-year-old male; a drainage tube can be seen entering the anterior chamber from the right of the image.

Fig. 28.3, A large limbal diameter rigid lens has been fitted to protect a neurotrophic corneal lesion in the early stages of the healing process.

Scleral Lenses

Scleral lenses have numerous therapeutic roles ( ). Their advantages include the following:

there is no corneal contact whatsoever;
any eye shape can be fitted;
complete protection of the cornea and bulbar conjunctiva is provided;
sealed fits are possible, using gas-permeable materials, which simplifies the fitting process and minimizes ‘settling’; and
overnight wear is possible.

At one time, the fitting, and especially the ventilation, of scleral lenses required much practical experience. With the advent of gas-permeable scleral lenses, however, sealed fits have become the norm and less skill is required. So many rehabilitative and therapeutic indications have demonstrated that it can now be regarded as essential for specialist contact lens clinics to offer and fit scleral lenses (see Chapter 17 ).

Concurrent Medications

Nonpreserved unit-dose eye drops are indicated for concurrent use with soft and scleral lenses. Preserved eye drops are rarely used in this situation, because of concerns that preservatives such as benzalkonium chloride can accumulate in the soft lens or remain entrapped in the postscleral lens fluid reservoir and be toxic to the corneal epithelium. This effect is usually of no clinical importance when disposable lenses are used for short periods. Prescription medications, oily or viscous drops or ointment should not be used concurrently with contact lenses.

Scleral lenses may also be used as ocular drug delivery systems. It has been reported the use of nonpreserved antibiotics, anti-VEGF and stem cells with scleral lenses for ocular surface treatment ( ).

Indications

A contact lens may be fitted therapeutically for the relief of pain or discomfort or to assist in the healing of injured or diseased ocular tissue. Sometimes a therapeutic lens simultaneously addresses more than one clinical problem; it may additionally, be used to correct a refractive error and has the potential to deliver ophthalmic drugs to the ocular surface. The various indications for fitting therapeutic lenses are considered below.

Surgery

Soft bandage contact lenses increase comfort and enhance healing after penetrating keratoplasty, ptosis, pterygium, intracorneal ring segments and phacoemulsification (see Chapter 29 ).

Penetrating Keratoplasty

Bandage contact lenses are used after penetrating keratoplasty to promote re-epithelialization, prevent suture irritation and reduce irregularities in the wound margin ( ). Factors that influence the success of lens wear are the health status of donor and recipient corneas, surgical parameters and postoperative treatment ( ).

Ptosis

Soft bandage contact lenses are beneficial after ptosis surgery. have investigated the comfort of soft bandage contact lens wear after ptosis surgery. A soft contact lens was applied in only one eye; in the contralateral eye, no contact lens was applied. Patients reported significantly increased comfort in the eye where a contact lens was fitted. verified the efficacy of soft bandage contact lens wear in children after congenital blepharoptosis and found that patients wearing the lens experienced less ocular discomfort than the control group without contact lens use.

Pterygium

Studies on the use of a bandage contact lens after pterygium surgery are contradictory. Various studies have found that soft contact lens wear significantly reduced pain ( ) and enhanced epithelial healing ( ). In contrast to these findings, other studies did not find soft contact lens wear beneficial after pterygium surgery ( ). Interestingly, found worse pain levels in patients wearing contact lenses.

Intracorneal Ring Segments

Various reports described the successful use of soft bandage contact lenses after intracorneal ring segments for corneal recovery and comfort ( ).

Phacoemulsification

Bandage contact lenses may be used after cataract surgery to reduce symptoms of dry eye. Two different studies demonstrated significantly reduced dry eye symptoms in patients wearing soft contact lenses after phacoemulsification ( ).

Keratorefractive Procedures

Lens application has been shown to be important after keratorefractive procedures to attain optimal pain control and epithelial healing ( ) (see Chapter 29 ).

Photorefractive Keratectomy

found that after PRK, patients treated with two topical agents (anaesthetic and nonsteroidal antiinflammatory eye drops) and soft bandage contact lenses experienced less pain than patients treated only with topical agents, without bandage lenses. Soft bandage lenses are routinely used for 3–5 days for pain relief following refractive surgery procedures with epithelial removal ( ).

The results of studies comparing silicone hydrogel to hydrogel lenses after PRK are contradictory. Referring to the study by , a silicone hydrogel lens resulted in significantly faster corneal re-epithelialization and reduced patient discomfort compared to a hydrogel lens. did not find a difference in the rate of re-epithelialization. Although patients experienced a higher level of pain and greater prevalence of haze with the hydrogel lens, more infiltrates were observed with the silicone hydrogel lens ( ).

Laser-Assisted In Situ Keratomileusis

Soft bandage contact lenses may be used after laser-assisted in situ keratomileusis (LASIK) to reduce symptoms, promote wound healing and potentially prevent epithelial ingrowth. Therapeutic contact lenses, soft and scleral, are also beneficial to manage epithelial defects secondary to LASIK.

Two studies have evaluated the use of soft bandage contact lenses compared to no lens wear in patients who have undergone LASIK ( ). In the study by , contact lenses were removed one hour after the procedure in 29% of patients because of intolerance. The authors concluded that soft bandage lenses significantly reduced symptoms for up to four hours immediately after LASIK. Flap oedema and mucoid discharge at the lid margins were noted in overnight wear. In the prospective study by , patients experienced less pain and photophobia when wearing contact lenses compared to the control group without lens wear. However, when wearing contact lenses, patients complained of a foreign-body sensation. The authors also found that eyes wearing contact lenses had a less intense wound healing response at the flap margins compared to control eyes.

Studies evaluating the use of soft bandage contact lenses to prevent epithelial ingrowth are anecdotal. No difference was found in epithelial ingrowth in two retrospective studies ( ). Conversely, in a cohort study, only 3 eyes of 783 eyes who had undergone LASIK developed epithelial growth within the interface, with a minimum of 3 months of follow-up ( ). The authors of the latest study concluded that cleaning the stromal interface properly during surgery combined with a soft bandage contact lens may significantly reduce the incidence of epithelial growth within the interface.

Soft bandage contact lens use after LASIK may alter corneal topography in terms of asphericity and induce corneal oedema ( ). Asphericity changes were caused by soft contact lens mechanical pressure and corneal oedema.

Soft bandage contact lenses have been shown to be effective in managing complications after a LASIK procedure. Eyes with epithelial loosening ( ), epithelial defects ( ) and corneal flap dehiscence ( ) were effectively treated with therapeutic lenses.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here