(A) The best method to test for a wound leak is with fluorescein dye. Use a wet fluorescein strip and paint the wound margin.
In contrast to using the conventional pressure patch, a bandage contact lens allows concurrent application of medications, allows the physician to observe the eye without removing the bandage, allows the patient to have usable vision in the affected eye and offers significantly better cosmesis along with the ability to wear spectacles or sunglasses as needed. An important aspect of bandage lens dressing design lies in matching the base curve of the lens to the radius of curvature of the cornea – referred to as lens fit.
Postoperative management is a series of judgment calls concerning wound management. Managing a bleb during the first postoperative month is more an art than a science.
3.If the IOP appears reasonable but the bleb is scarring down by weeks 2 to 3, consider laser to another suture to try to increase flow. Blebs that appear vascularized need increased flow if possible. Low IOP is usually avoided by titrating flow in the operating room.
Other methods to trap drugs and release them from contact lenses include molecular imprinting, colloid encapsulation, and polymeric nanoparticles (Dixon et al., 2015 ; Maulvi et al., 2016 ). Ciolino et al. examined the properties of a copolymer of poly(hydroxyethylmethacrylate) and methacrylic acid (pHEMA/MAA) contact lens that encapsulated a poly(lactic-co-glycolic) acid (PLGA) film that incorporated the glaucoma drug latanoprost. They demonstrated that as the PLGA drug film degraded, the contact lens delivered a therapeutic amount of the drug over a 4-week period in vivo without any signs of cytotoxicity (Ciolino et al., 2014 ).
So far, Mr. Packard has conducted preliminary cases in preparation for a planned clinical trial; in these cases cataract surgery was performed under topical anesthesia, with eyes receiving a foldable intraocular lens through a 2.2-mm clear corneal incision. The use of antimetabolites has extended the time window for laser suture lysis.
If the leak is persistent or is made worse with suturing, one must consider a trip back to the operating room for a more definitive closure. (B) Occasionally, the leak will be due to a buttonhole in the bleb; again, this is more common in a revision of a filter. Management of a buttonhole consists of a large bandage contact lens to cover the site.
In atopic keratoconjunctivitis and vernal conjunctivitis, contact lens wear is contraindicated due to complications involving the eyelids, palpebral conjunctiva and cornea. Bandage contact lenses may be indicated in severe cases involving the cornea (see Chapter 26 ). Several decades ago, cycloplegics were routinely used after filtration surgery. The need for these drugs has lessened with guarded flaps and lower tendency for flat anterior chambers.
A pressure patch is also useful. Even if the IOP is low, aqueous suppressants may be useful to slow down aqueous flow at the leak site. Reducing topical corticosteroids may be beneficial until the leak is healed. Suffice it to say, a wound leak creates considerable consternation for both the patient, who usually has tearing and poor vision, and the surgeon, who is trying to modulate wound healing under duress. Bandage contact lenses can provide pressure-patching type relief for patients with Thygeson’s superficial punctate keratitis and those with superior limbic keratoconjunctivitis.
The goal of bandage lens therapy in such cases is to provide an initial release of the drug into the eye and then a slower, long-term release throughout the duration of lens wear. These lenses also have roles immediately following penetrating keratoplasty. Tarsal plate protection is often necessary in procedures that result in interrupted sutures with non-buried knots. The contact lens smoothes the ocular surface, providing better ocular comfort and preventing mechanically induced papillary conjunctivitis.
Ectatic conditions such as keratoconus, pellucid marginal degeneration and Terrien’s marginal degeneration are typically managed with gas-permeable contact lenses. However, as the conditions progress, epithelial compromise can occur secondary to the inability to provide a stable GP contact lens fit. In these cases, a soft contact lens will have therapeutic benefit in providing a more stable base on which to place the gas-permeable contact lens and at the same time protect the corneal surface.
The amount of uptake and release of drugs from contact lenses soaked in the medications has been reported in the literature, and inconsistencies exist with respect to material interactions, lens water content and ionic character. Given the benefits of silicone hydrogel contact lenses, which include the virtual elimination of complications related to hypoxia in the normal eye, it would make sense to try this modality as the initial lens of choice for therapeutic applications. It can be expected that the increased oxygen permeability will more effectively promote healing by reducing the risk of hypoxia-related interference. This is of prime importance when the contact lens must be worn on a continuous-wear basis for several months.
A poorly fitting lens will impact on the underlying epithelium especially during the blink which may cause further epithelial erosion. Significantly, no lens has been specifically designed as an actual BL, they are simply cosmetic lenses used for a healing benefit.
If one uses a bandage contact lens for tamponade, the lens should stay in place for 1 to 2 weeks (to allow the tissue to heal) before attempting removal. Repeated placement and removal of the contact lens traumatizes the area and impedes healing. The patient should also be started on a topical antibiotic drop to prevent an infection.
Bandage contact lens complications are typically either mechanical in nature from the close apposition between the contact lens and the ocular surface or an inflammatory response from entrapped debris underneath the lens. Because the lenses are used on an already-compromised ocular surface, judicious follow-up is imperative. The first visit after the initial bandage lens is dispensed should be within 24 hours and then again in 3 to 7 days. Weekly follow-ups thereafter for the first month are also suggested.
This is, in large part, a consequence of the extensive ocular compatibility studies that have underpinned the development of commercial contact lens materials. The published information in this area contrasts with the limited available information on biomolecular aspects of wound dressing-wound bed interactions. Therapeutic bandage contact lenses promote epithelial migration and regeneration of the basement membrane by protecting the corneal epithelium from the friction created by the upper tarsal conjunctiva.23 To be effective, a bandage contact lens should be worn for a few weeks to several months, 16 replacing it every 2 weeks. This may enable the formation of stable adhesion complexes between the corneal epithelium and the basement membrane. Any time medical therapy is indicated and a bandage contact lens is used, the customary dosage and instillation therapy should not be altered.
Drug delivery in the eye, and the biomaterials used in general, is a large topic and will not be covered further in this article. Both photorefractive keratectomy and laser epithelial keratomileusis induce a large epithelial defect and require the continuous wear of a bandage contact lens for 3 to 4 days post-surgery or until complete re-epithelialization occurs. Once again, the lenses provide pressure-patching pain relief as well as corneal protection while allowing examination of the healing surface and allowing the patient usable vision during the process. Figure 77-10 . Dye test and management.
The timing of laser suture lysis post trabeculectomy is critical.66 Laser the suture too early and hypotony is a problem, and waiting too long leads to filtration scarring and failure to control IOP (Box 77-6 ). This dilemma is a judgment call. Eyes that undergo laser suture lysis more than 10 days after initial trabeculectomy with mitomycin C are more likely to have poorer long-term IOP control than eyes not requiring laser suture lysis or eyes undergoing laser suture lysis less than 10 days after surgery.67 Thus, the need for suture lysis in the first 2 weeks after surgery typically indicates that the bleb is scarring, granted adequate initial flow. Adhesive bandages are the best way to protect minor wounds and burns.
It is important to leave the lens in place for many weeks after the erosion resolves to allow epithelial migration and attachment without the interference of the shearing forces of the upper lid. If the lens needs to be replaced, it can be carefully floated off with saline solution in-office and replaced. When treating abrasions, the contact lens acts a barrier to further epithelial disruption and corneal nerve stimulation by the shearing force of the upper lid during the blink. Additionally, there is evidence that a lens can prolong contact time of topical ocular medications.
Remember to carefully clean and disinfect the wound before applying. Even so, the authors concluded that, for all lenses, the drug release was well above the MIC90 for commonly found pathogens and that the improved physiologic characteristics of high-Dk lenses should still be considered a better alternative for bandage and therapeutic lenses than low-Dk contact lenses.
They're usually sold in single pad packs. This breathable bandage isolates and protects your wound without irritating the skin.
For many years, surgeons have noted the potential advantages of a liquid sealant that could be placed directly onto ocular wounds following surgery. Such a product could potentially protect the eye from leakage, increase surgical efficiency, reduce or eliminate the possibility of endophthalmitis and eliminate the need for sutures. Over the years, a number of products have been used off-label for this purpose, but recently companies have begun producing hydrogel-based materials specifically designed for use on the eye.
Another potential application for contact lenses is their use in drug delivery to the front of the eye; this would be beneficial as there is a low bioavailability of ophthalmic eye drop (about 5%) due to the high drainage via the tear duct or down the cheek. One of the challenges is to achieve a sustained therapeutic release of the drug over a period of time. Simple methods involve soaking commercial hydrogel contact lenses in solutions containing drugs; however, the release profile of the drug is uncontrolled, leading to an initial high overdosing period over a few hours followed by a long underdosing period, making them unsuitable for long-term release. An alternative method is to immobilize drugs onto the surface of hydrogel contact lenses that may require modification using polyethylene glycol (Kirchhof et al., 2015 ; Xinming et al., 2008 ).
Bandage lenses are indicated in cases of corneal lacerations that are small with well-appositioned edges that do not cause wound gape. A contact lens can be used in conjunction with wound-closing therapies such as suturing or cyanoacrylate glue to protect the eye from mechanical trauma and promote pain relief. Probably the most common reason for choosing bandage contact lens therapy is to manage corneal surface disruption secondary to either trauma or dystrophic disease.
If necessary, try focal pressure at the bleb area and see if the bleb elevates; if not, use medications for a day or two. Management of the anterior chamber is essential as well. Look for flare and cell and if greater than +1, consider increasing topical corticosteroids.
If a leak is found, the aqueous will further dilute the dye and a stream of aqueous is easily identified. The patient should look to the right and left during this to try to elicit a leak. Very mild pressure on the eye may be necessary in some cases. If a leak is identified in the early postoperative period, a variety of techniques can be considered, such as a bandage contact lens to tamponade the leak, cessation of topical corticosteroids, and/or commencing aqueous suppressants. If these conservative measures do not work, consider a suture placed at the limbus to close the leak.
If, after the first week the bleb becomes smaller or flat, suture lysis is required. High IOP usually correlates with inadequate flow through the scleral flap and, if not corrected, filter failure. Laser suture lysis on the first day may be hazardous. It is not unusual for the IOP to be elevated on day 1 or 2 due to debris blocking the filter.
4.If the patient is at high risk for choroidal effusion, delay suture lysis. It is possible to nurse a bleb along with focal massage every other day until a constant flow can be established with suture lysis. Antimetabolites may also buy time until filtration can be increased. 2.Typically, if the IOP starts off in the low to mid teens and elevates by the first week, it is generally safe to laser a suture. Recheck IOP, and if no flow, consider laser to a second suture.
Thus there is an unmet challenge for therapeutic bandage lenses that are specifically designed for the injured (accident or surgery) or diseased cornea to aid healing. The specifically designed BCLs should allow mechanical protection of the cornea from eyelid movement. They also should protect the corneal surface from atmospheric exposure and further ocular insult and should limit dehydration while potentially improving the ability of the corneal epithelium to heal. Likewise, the potential to load the lens with drugs for prolonged drug delivery may prove to be hugely beneficial.
One Canadian study suggested that bandage contact lenses were not necessary for LASIK post-operatively, but they conceded that in the cases studied no post-operative complications were encountered rendering use of the lenses unnecessary (Ahmed and Breslin, 2001 ). There are many conflicting reports relating to the use of bandage lenses and in particular the net benefit to the patient. The anterior ocular surfaces include the cornea, conjunctiva, sclera and lids of the eye. In the anterior eye one of the most commonly used biomaterials is the soft contact lens.
In the anterior healing eye a bandage contact lens can be used to protect an injured or diseased cornea from external factors thereby improving its ability to heal. Such lenses are referred to as therapeutic, as distinct from cosmetic, lenses and if no refractive correction is required plano lenses are used. Therapeutic contact lenses are used in a variety of conditions including dry eye, allergy, ulcers and persistent epithelial defects. One of the few attempts to ascertain the frequency of use of bandage lenses (BLs) in North America revealed that the most common uses of BLs were for corneal wound healing and post-operative complications, being prescribed by 72% of the ophthalmic practitioners who answered the survey ( Karlgard et al., 2002 ).
In most instances, the 8.4-mm base curve of the Focus Night & Day will be first choice, although extremely tight-fitting lenses are never indicated, as toxic debris entrapment beneath the lens is potentially problematic. In instances where an appropriate fit cannot be obtained or when the silicone hydrogel fails due to other issues such as discomfort, it is prudent to consider other lenses approved for therapeutic use.
Every postoperative visit involves a discussion on how much topical steroid is required. Soft contact lenses can serve as a reservoir when soaked in topically applied medications and have the ability to uptake and release the medication.
The advent and popularity of elective refractive laser surgery has opened up a whole new area in ocular wound healing and has allowed researchers to study corneal insult and biomaterial interaction more closely. Laser in situ keratomileusis (LASIK), laser in situ epithelial keratomileusis (LASEK) and photorefractive keratectomy (PRK) are the most commonly performed procedures. Laser eye surgery involves excimer laser ablation of the underlying cornea accessed by folding back a hinged corneal circular flap which is created by means of a microkeratome or by laser. Following refractive surgery soft contact lenses are commonly used as bandage lenses to protect the cornea, relieve pain and assisting in corneal flap healing. In the early days of LASIK a bandage lens would be worn for weeks but with advances in the technology the bandage lens is now generally only worn for a day.
However, even under the best of circumstances, hypotony can occur. Caution the patient to avoid straining or any activity that could raise episcleral venous pressure until the IOP increases.
1.Try to avoid laser scleral flap suture (SFS) lysis on day 1, especially if flow was generous in the operating room. Swelling or debris, especially blood, may temporarily clog the filter. If SFS lysis is performed too early and the clot dissolves the next day, hypotony will present.