Therapeutic Contact Lenses in the Treatment of Corneal and Ocular Surface Diseases—A Review

Abstract

Therapeutic contact lenses (TCLs) are often used in the management of a wide variety of corneal and ocular surface diseases (OSDs). Indications of TCL include pain relief, enhancing corneal healing, corneal sealing, corneal protection, and drug delivery. For painful corneal diseases such as bullous keratopathy, epidermolysis bullosa, and epithelial abrasions/erosions, bandage contact lenses (BCLs) provide symptomatic relief. Postoperatively in photorefractive keratectomy or laser epithelial keratomileusis, BCLs also alleviate pain. In severe OSDs such as severe dry eye, Stevens-Johnson syndrome/toxic epidermal necrolysis, gas-permeable scleral contact lenses are often used to enhance corneal healing. BCLs are used post-keratoplasty, post-trabeculectomy, and post–amniotic membrane transplantation to enhance healing. BCLs, with or without glue adhesives, are used to seal small corneal perforations and sometimes also used as bridging treatment before penetrating keratoplasty in larger corneal perforations. In patients with eyelid conditions such as trichiasis, ptosis, and tarsal scarring, BCLs are also effective in forming a mechanical barrier to protect the cornea. A relatively new use for TCLs is in ocular drug delivery where TCLs are used to maintain therapeutic concentrations of medication on the ocular surface. Contraindications of the use of TCLs include infective keratitis, corneal anesthesia, and significant exposure keratopathy with inadequate eyelid position or movement. Complications of TCL include infective keratitis, corneal hypoxia and associated complications, corneal allergies and inflammation, and poor lens fit. Overall, TCLs are effective in the treatment of corneal and OSDs but contraindications and complications must be considered.

Contact lenses play an important role in the therapeutic management of corneal and ocular surface diseases (OSDs). The types of contact lenses used for therapeutic purposes include soft lenses and scleral lenses. They exert therapeutic benefit by forming a mechanical barrier between the cornea and the external environment, hydrating the corneal epithelium, increasing corneal wound healing, and providing pain relief. Therapeutic lenses are used to manage a wide variety of corneal conditions including bullous keratopathy, corneal erosions, corneal epithelial defects, and postsurgical conditions such as post-keratoplasty and post–laser vision correction.

OSD is an umbrella term encompassing a wide variety of conditions affecting the ocular surface. These conditions include dry eye disease, blepharitis, meibomian gland dysfunction, and immunologic disorders. Current conservative management options for OSD include artificial tears, topical antihistamines, steroids and immunologics,¹ and therapeutic contact lens (TCL) usage.

The purpose of this review article is to evaluate the indications, contraindications, complications, and fitting principles of contact lenses in the treatment of corneal and OSDs.

INDICATIONS FOR THE USE OF TCLS IN OSDs

There are many indications for the use of TCLs in corneal and OSDs. In this article, the indications are divided into 5 broad categories: pain relief, enhancing corneal healing, corneal sealing, corneal protection, and drug delivery (Table 1).

TABLE 1 - Indications of Therapeutic Contact Lenses

Pain Relief	Enhance Corneal Healing	Corneal Protection	Corneal Sealing	Drug Delivery
Bullous keratopathyEpithelial abrasions/erosionsPost–laser vision correction: PRK/PTK/LASEK/LASIK	Chronic epithelial defects/ulcersHerpes simplex metaherpetic ulcerNeurotrophic keratitisChemical burnsDescemetoceleFilamentary keratitis (Fig. 1B)Dry eyesPost-keratoplastyPost–amniotic membrane transplantPost-trabeculectomy	EntropionTrichiasisTarsal scarringRecurrent corneal erosionsPtosis	Corneal perforations	Ocular surface drug delivery

LASEK indicates laser epithelial keratomileusis; LASIK, laser-assisted in-situ keratomileusis; PRK, photorefractive keratectomy; PTK, phototherapeutic keratectomy.

Pain Relief

In painful conditions such as bullous keratopathy (Fig. 1A), epidermolysis bullosa, and epithelial abrasions/erosions, bandage contact lenses (BCLs) are commonly used to provide pain relief.^2–5 For recurrent corneal erosions, a randomized controlled trial showed that although the use of BCLs may not increase the likelihood of complete resolution when compared with ocular lubrication, some patients may experience earlier relief from symptoms.⁶

FIGURE 1: Indications for therapeutic lens wear. A, Painful bullous keratopathy. B, Cobalt blue filter image with fluorescein dye showing filamentary keratitis in severe dry eye disease secondary to rheumatoid arthritis. C, Post-DSAEK surgery day 1 showing the DSAEK graft well adhered to the cornea with 30% of anterior chamber air fill and bandage lens wear (corneal epithelium was debrided hence bandage lens was used). D, Bandage lens wear for post–amniotic membrane transplantation for chronic epithelial defect following acanthamoebal keratitis. DSAEK indicates descemet membrane stripping automated endothelial keratoplasty.

BCLs are also used postoperatively to aid in pain relief. After refractive surgery procedures such as photorefractive keratectomy (PRK) or laser epithelial keratomileusis (LASEK), it is standard practice to place a bandage lens for better pain relief.⁷ A prospective randomized controlled contralateral eye study showed that wearing soft contact lenses had significant and clinically meaningful beneficial effects in visual recovery, pain perception, and reduced haze formation post-PRK as compared with no contact lens wear.⁸ Silicone-hydrogel (SiHy) contact lenses have been shown to be more significant in reducing subjective pain responses as compared with non-SiHy contact lenses post-LASEK.⁹ A review article by Sanchez-Gonzalez et al¹⁰ summarized several studies comparing the efficacy of different kinds of SiHy contact lenses in pain relief and aiding corneal reepithelialization. In the 13 articles reviewed, 8 SiHy lenses were compared (Asmofilcon A, Balafilcon A, Comfilcon A, Etafilcon A, Lotrafilcon A, Lotrafilcon B, Omafilcon A, and Senofilcon A).^8,11–22 Of all materials compared, Senofilcon A had the lowest pain scores and Lotrafilcon A had the fastest epithelial healing post-PRK.¹⁰ A subsequent comparative study between Samfilcon A and Lotrafilcon B SiHy contact lenses showed that Samfilcon A lenses were superior in reducing postoperative pain and accelerating re-epithelialization.²³ Additionally, soft contact lenses have also been shown to be successful in reducing postoperative pain after autograft pterygium surgery.²⁴ Although the use of BCLs in laser-assisted in-situ keratomileusis (LASIK) is not widespread and currently depends on surgeon preference, a prospective randomized clinical trial showed that patients felt less discomfort and had a less intense wound healing response in eyes with BCLs as compared with control eyes post–femtosecond LASIK.²⁵ However, the use of BCLs in pain relief post–pterygium surgery had mixed results. One randomized clinical trial found that the group with BCLs had faster corneal epithelial healing (measured with ultrahigh-resolution optical coherence tomography) and lower pain levels (according to visual analog scale scores) as compared with the control group.²⁶ Another randomized clinical trial showed that BCLs resulted in more discomfort and pain and decreased quality of sleep as compared with tight bandage patching post–pterygium surgery.²⁷

The actual mechanism responsible for the symptomatic pain relief after applying BCLs is not clearly established. However, a possible theory is that BCLs provide a mechanical shield to the eye resulting in less mechanical abrasion/contact from external eye structures such as eyelids.

Enhance Corneal Healing

In patients with corneal and OSDs, either bandage soft contact lenses or scleral lenses can be used to enhance corneal healing.

BCLs promote epithelialization by forming a scaffold and improving the spread of tear fluid over the ocular surface. In a comparative study, patients wearing BCLs for the treatment of neurotrophic keratitis had shorter corneal ulcer healing times compared with patients treated solely with eyedrops alone.²⁸ BCLs, in particular SiHy lenses, are also effective in promoting healing in ocular chemical injuries.²⁹ Bandage soft contact lenses were also investigated in the treatment of moderate to severe ocular graft-versus-host disease and found to be a safe, tolerable, and effective treatment option for patients who remained symptomatic despite conventional treatments.³⁰

In severe OSDs, gas-permeable scleral contact lenses are often used (Table 2).^31–43 In this article, we classify scleral lenses according to the resting zone area of the lens on the ocular surface (the current recommendation by the Scleral Lens Education Society)⁴⁴ and move away from using diameter classification, which was the previous recommendation, since it would not be accurate for extremely large or small eyes.⁴⁵ As such, corneal lenses are lenses which rest entirely on the cornea, corneo-scleral lenses are lenses which rest partly on the cornea and partly on the sclera, and scleral lenses are lenses which rest entirely on the sclera. Scleral lenses work by providing a tear-filled precorneal chamber and providing increased protection to the cornea from desiccation and friction.⁴⁶ There have also been studies on the use of Prosthetic Replacement of Ocular Surface Ecosystem [PROSE; also known as Boston Scleral Lens, Boston Scleral Lens Prosthetic Device (BSLPD), or Boston Ocular Surface Prosthesis (BOSP)] in OSDs. In a retrospective review of all available records of patients fitted with Boston Scleral Lens in a center in the United States, it was found that this scleral lens is an important front line tool for the management of many severe corneal disorders refractory to other treatment measures or otherwise requiring keratoplasty.³¹ The most common indication was Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), followed by severe dry eye and neurotrophic disease.³¹ Other retrospective studies also concurred that scleral lenses improve symptoms, visual outcomes, and corneal healing in severe OSDs,^32–34 and SJS/TEN.^35,36 Esclera and BSLPD lenses have also been shown in prospective case series to improve visual acuity, dry eye symptoms, and quality of life in dry eye patients.^37,38 In retrospective case series, PROSE lenses had also been shown to be successful in improving visual acuity and Ocular Surface Disease Index scores in patients with exposure keratopathy^39,40 and SJS.^41,42 Additionally, there are case reports which show that scleral lenses have been successfully used in specific conditions such as exposure and neurotrophic keratopathy,⁴⁷ mucous membrane pemphigoid,⁴⁸ and Graves ophthalmopathy.⁴⁹

TABLE 2 - Therapeutic Use of Scleral Lenses in the Treatment of Corneal and Ocular Surface Diseases

Author	Type of Study	Indication of Scleral Lens	No. Eyes	Scleral Lens Type	Outcome
Rosenthal and Croteau, 200531	Retrospective	Severe OSD	875	Boston Scleral Lens	Improved vision, reduced ocular pain and photophobia, healing of corneal defects
Scanzera et al, 201932	Retrospective	OSD and CI	133 Patients	Jupiter, BostonSight PROSE	Visual outcomes improved with scleral CL for both indications —CI and OSD
Schornack et al, 201433	Retrospective	OSD	188	Jupiter	Improved comfort, ocular surface protection, or resolution of keratopathy achieved in all but 2 subjects
Jacobs and Rosenthal, 200737	Noncomparative interventional case series	Dry eye from chronic GVHD	33 Patients	BSLPD	Improvement in pain, photophobia, and general QoL
Lee et al, 201834	Retrospective	Severe refractory OSD	13	SoClear lens∗ (corneo-scleral)	Improvement in BCVA, CFS score, and PED
Tougeron-Brousseau et al, 200935	Retrospective	SJS/TEN	67	SPOT†	Significant improvement in VA, OSDI, and NEI VFQ-25 scores
La Porta Weber et al, 201638	Prospective interventional case series	Moderate to severe dry eye disease	41	Esclera	Significantly improved BCVA, decreased tear osmolarity and van Bijsterveld scores, improved DES and QoL scores
Rathi et al, 201136	Retrospective	CI and SJS	23 (CI); 20 (SJS)	BOSP	Improved VA and symptoms in both CI and SJS
Suarez et al, 201843	Prospective case series	Keratoconus, post-PK, irregular astigmatism, severe OSD	39	ICD 16.5 mini–scleral lens	Effective and safe option
Chahal et al, 201739	Retrospective interventional case series	Exposure keratopathy	18 Patients	PROSE	Improvement in VA, OSDI, and corneal staining values
Wang et al, 201941	Retrospective interventional case series	SJS in pediatric patients	49 Patients	PROSE	Significantly improved BCVA. 15 patients failed treatment
Heur et al, 201442	Retrospective interventional case series	SJS	27	PROSE	Significantly improved VA and OSDI scores
Kalwerisky et al, 201240	Retrospective interventional case series	Exposure keratitis from severe periorbital thermal injuries	16	BOSP	Successful rehabilitation of ocular surface with BOSP

BCVA indicates best-corrected visual acuity; BOSP, Boston Ocular Surface Prosthesis; BSLPD, Boston Scleral Lens Prosthetic Device; CFS, corneal fluorescein staining; CI, corneal irregularity; CL, contact lens; DES, dry eye symptoms; GVHD, graft-versus-host disease; NEI VFQ-25, National Eye Institute Visual Function Questionnaire-25; OSD, ocular surface disease; OSDI, Ocular Surface Disease Index; PED, persistent epithelial defect; PK, penetrating keratoplasty; PROSE, Prosthetic Replacement of the Ocular Surface Ecosystem; QoL, quality of life; SJS, Stevens-Johnson syndrome; TEN, toxic epidermal necrolysis; VA, visual acuity.

^∗Art Optical Contact Lens, Inc., Grand Rapids, MI, USA, Clean & Bright Cooperation.

^†LAO, Thonon-les-Bains, France.

BCLs are widely used to enhance corneal healing post–ocular surgery, for example, after keratoplasty procedures such as penetrating keratoplasty.⁵⁰ More recently, BCLs have been used after anterior lamellar keratoplasty and endothelial keratoplasty procedures (Fig. 1C). However, a recent randomized clinical trial has shown that there are no significant benefits of BCL application at the time of corneal transplantation.⁵¹ There was no difference in the speed of epithelialization between the BCL group and the control group. Certain limitations of this clinical trial include the relatively small sample size of 26 eyes and the use of hydrogel BCL instead of the newer, more effective SiHy lenses.⁵¹ Further studies on this subject are required to elucidate this matter. Other procedures requiring BCL include amniotic membrane transplantation (Fig. 1D).

A prospective randomized controlled study looked into the prophylactic use of BCL in the reduction of dry eye symptoms post-phacoemulsification and found that patients who wore BCLs for 1 week had statistically significant improvements in Ocular Surface Disease Index scores, subjective evaluation scores, tear break-up time, and fluorescein staining.⁵² Another randomized clinical trial which evaluated the use of therapeutic BCL in post-cataract patients concluded with similar findings of improved tear break-up time, tear meniscus height, subjective feeling, and corneal fluorescein staining in the BCL group compared with the control group.⁵³

Some specialty soft therapeutic lenses (eg, Kontur, Richmond, Calif) have much larger diameters to facilitate coverage of the paralimbal region and the adjacent conjunctiva and have been used successfully in post-trabeculectomy cases to manage bleb-related complications such as bleb leaks, bleb enlargement in cases of hypotony and to prevent pain from conjunctival suture abrasive trauma to the eyelids. A prospective, randomized clinical trial has shown that post-trabeculectomy patients who wear soft BCLs (PureVision, 14 mm) had significantly higher mean intraocular pressure values, increased life table rates of surgical success, lower use of antiglaucoma medications, a more diffused bleb area, and lower incidence of encrusted blebs.⁵⁴ In other studies, although the diameter of contact lens used is not standardized, large diameter contact lenses (14–20.5 mm) have been used in post-trabeculectomy patients and are effective in treating bleb leaks^55–57 and early hypotony.^58,59 The contact lens works by forming a barrier which reduces leak flow and by preventing transconjunctival filtration, promoting the restoration of the anterior chamber.

Corneal Protection

In patients with lid conditions such as trichiasis, post–ptosis surgery, recurrent corneal erosions, and tarsal scarring, the contact lens serves as a shield and protects the corneal surface from the eyelids and eyelashes.⁵ Together with eye lubrication and mechanical epilation, contact lenses are an established form of nonsurgical treatment for trichiasis.⁶⁰ Although soft BCLs are usually used, a case series reports the use of PROSE in complex oculoplastic diseases and severe corneal surface diseases.⁶¹ Patients with ptosis showed improvement in marginal reflex distance after PROSE and many were spared further surgical intervention. Other patients with ectropion, entropion, or trichiasis also experienced improvement.⁶¹ In severe cicatricial entropion where surgical repair is difficult, a prospective cohort study showed that an acellular dermis allograft (ReDerm, Jieya company, Beijing, PR China) coupled with the use of TCLs is effective in treatment.⁶²

Corneal Sealing

The contact lens acts as a splint for corneal perforations and lacerations and may be effective in sealing small perforations and lacerations with and without adhesives⁶³ (Fig. 2). A study conducted at the Singapore National Eye Center by Lim et al⁶⁴ reported effective use of silicone-hydrogel lenses (Bausch and Lomb PureVision Lenses, Rochester, NY) for corneal wound sealing purposes in corneal perforations <2 mm in diameter. Even in larger corneal perforations, fibrin glue and therapeutic BCLs are often used as a temporizing measure before penetrating keratoplasty, since outcomes for penetrating keratoplasty are often poor in the presence of active inflammation.^65,66

FIGURE 2: Management of corneal perforation with cyanoacrylate glue and bandage lens. (A, B) 2 mm corneal perforation following herpetic stromal keratitis showing the iris plugging the perforation. (C) Cyanoacrylate corneal gluing for corneal sealing with bandage lens application. (D, E) 6 months later, the cornea healed with fibrosis and vascularization under the cyanoacrylate glue with spontaneous dislodgement of the glue.

Drug Delivery

Ocular drug delivery involves achieving therapeutic concentrations of medication at the ocular surface. This is traditionally achieved through eye drops, sometimes frequent dosing is necessary to achieve therapeutic concentrations. Unfortunately, frequent dosing is inconvenient, not cost-effective, and often leads to patient noncompliance. To overcome these limitations found in conventional eye drop treatment, novel delivery systems and devices have been explored. It is suggested that therapeutic lenses may be suitable for controlled and sustained drug delivery due to their extended-wear function and higher bioavailability than eye drop formulations.⁶⁷ The drug delivery techniques include soaking method, molecular imprinting, entrapment of drug-laden colloidal nanoparticles, drug plate, ion ligand polymeric systems, and superficial fluid technology.^68–70

Contact lenses can be either presoaked or postsoaked in a drug solution. Presoaked means that contact lenses are soaked in the drug solution before application on the ocular surface, whereas postsoaked refers to applying the contact lens first on the ocular surface before placing eye drops on the lens. Contact lenses, being hydrophilic, can be used for prolonged release of medication onto the ocular surface.^71,72 Simulation and in vitro experiments have shown promising results—drug delivery from a contact lens is more efficient than drug delivery by eye drops, with larger fractional uptake and higher bioavailability.^73–75 Particle-laden contact lenses have also been investigated in drug delivery. These lenses have colloidal particles (commonly liposomes) embedded in them for sustained delivery. Both in vitro and ex vivo studies have shown liposomal contact lenses to be biocompatible.⁷⁶ The liposomes embedded in the contact lenses also do not affect transmittance within the visible light range.⁷⁶ Drug delivery modalities such as molecular imprinting and ion ligands bind specific molecules and are promising in providing targeted drug delivery.

Although research on TCLs in drug delivery appears promising, there are currently limited clinical and commercial applications. Possible areas of application include the use of contact lenses in prophylactic antibiotic delivery, especially for extended contact lens wear, and in the delivery of glaucoma therapy. Basic lens properties such as transparency, water content, drug stability, drug release, swelling, and storage modulus and other properties affecting comfort such as ion and oxygen permeability need to be addressed before commercialization.

FITTING PRINCIPLES

Therapeutic lenses frequently need to be worn on an extended-wear basis and hence need to have a high oxygen transmissibility (Dk/L) to be suitable. The critical lens oxygen transmissibility needed to limit overnight corneal edema to 4% (the level experienced without a contact lens in place) was found to be 87 × 10^–9 (cm × mLO₂)/(s × mL × mm Hg).⁷⁷ Currently, most silicone-hydrogel lenses, but not hydrogel lenses, are able to fulfill this criteria (Table 3).

TABLE 3 - FDA-Approved Therapeutic Soft Contact Lenses

Trade Name	Lens Material	Dk/H2O	Base Curve, mm	Powers (D)
Acuvue Oasys (Vistakon)	Senofilcon A	103/38	8.4, 8.8	+8.00 to −12.00
PureVision (Bausch + Lomb)	Balafilcon A	99/36	8.3, 8.6	+6.00 to −12.00
Air Optix Night & Day Aqua (Alcon)	Lotrafilcon A	140/24	8.4, 8.6	+6.00 to −10.00

D inicates diopter; Dk, oxygen permeability; FDA, US Food and Drug Administration; H₂O, water content.

In the fitting of bandage soft contact lenses, the diameter of the soft lenses should be ≥13.5 mm for full corneal coverage and larger lenses (eg, Kontur lenses) may be required in certain conditions such as post–glaucoma filtration surgery cases. Commercially available therapeutic SiHy lenses frequently have limited base curvature options (usually 2, eg, 8.4 and 8.8 mm in Johnson and Johnson Acuvue Oasys lenses, Jacksonville, FL) and hence these lenses may not fit the whole range of corneal and OSDs, especially in post-keratoplasty eyes. The standard principles of contact lens fitting should be adhered and steep or flat fitting lenses avoided.

Prophylactic topical antibiotics are recommended in therapeutic lens wear as the risk of infective keratitis is higher in extended lens wear than daily lens wear. The use of single-use, preservative-free eyedrops is preferred where possible. In long-term bandage lens wear, periodic replacement, for example, monthly, to avoid protein and microbial buildup is important. The patient should be informed about the potential risks of TCL wear and followed up at regular intervals to check for complications.

CONTRAINDICATIONS

Although TCLs have many uses, there are certain contraindications that must be considered. These include infective keratitis, corneal anesthesia, and significant exposure keratopathy with inadequate eyelid position or movement. Therapeutic lens wear in infective keratitis may lead to worsening of the infective process and should be avoided.

A relative contraindication of therapeutic lens wear is corneal anesthesia. These patients have reduced pain sensation, lacrimal and blink reflex, and may be unable to detect symptoms of complications. In these patients, it is permissible to use contact lenses with close follow-up to detect intolerance or early complications. For patients with significant lagophthalmos and exposure keratopathy, localized drying of the contact lens surface would cause discomfort and mechanical abrasions to the ocular surface limiting its use.

COMPLICATIONS

Infective keratitis is one of the most devastating complications of contact lens wear. In a landmark Australian surveillance study by Stapleton et al,⁷⁸ the annualized incidence of microbial keratitis in contact lens wearers (per 10,000 wearers) was described. Overnight contact lens wearers had a much higher incidence of microbial keratitis than daily-wear contact lens wearers, with the highest incidence of microbial keratitis seen in overnight SiHy wearers [25.4 (21.2–31.5)], even compared with overnight conventional soft lens wearers [19.5 (14.6–29.5)] despite higher oxygen transmissibility in SiHy lenses. Pure daily-wear soft lens wearers had a much lower incidence of microbial keratitis [1.9 (1.8–2.0)] and the lowest incidence was seen in daily-wear rigid gas-permeable lens wearers [1.2 (1.1–1.5)].⁷⁸ For this reason, prophylactic antibiotics are used for extended contact lens wear. Poor hygiene, extended wear, and low oxygen permeability are contributing factors associated with a higher incidence of infections.^79–81 The most common organism in infective keratitis is Pseudomonas aeruginosa. Other organisms included Staphylococcus, Streptococcus, Serratia, and Acanthamoeba. Bacterial corneal ulcers can potentially be sight-threatening and require prompt broad-spectrum empiric antibiotics whereas the treatment of Acanthamoeba keratitis involves a cocktail of antiamoebic drugs.⁸²

Hydrogel lenses with low oxygen transmissibility can cause significant corneal hypoxia if worn on an extended-wear basis. Signs of corneal hypoxia include corneal stromal and epithelial edema with microcyst formation, corneal neovascularization, and endothelial complications.⁸³ SiHy lenses with higher oxygen transmissibility are therefore preferred.

Contact lens wear can also result in allergies and inflammation. Papillary conjunctivitis, sterile inflammatory reactions, and in severe cases, anterior chamber flare and cellular reactions can develop.^84–86

Poor fit of the contact lens can also result in certain complications. For lenses that are too steeply fit, a sucked-on-lens syndrome or anterior segment ischemia can develop. In patients with severe dry eye, lens loss can also occur due to the lack of surface tension.

SUMMARY

An algorithm shown in Figure 3 illustrates certain factors that should be considered before deciding on the use of TCLs. There are many indications and uses of TCLs in alleviating ocular pain, enhancing corneal healing, corneal protection, and corneal sealing. Recent advances in technology and research have also shown contact lenses to be promising in the use for drug delivery. However, there are certain contraindications of the use of TCLs that must be considered. These include infective keratitis, corneal anesthesia, and significant exposure keratopathy with inadequate eyelid position or movement. Complications of extended contact lens wear can also occur. There is a higher incidence of infective keratitis, the most devastating complication, in extended contact lens wear. Therefore, prophylactic antibiotics should be used. Patients should also be monitored for other complications such as corneal hypoxia leading to corneal edema and neovascularization, corneal inflammation, and allergic conjunctivitis.

FIGURE 3: Algorithm for therapeutic contact lens wear.