Ординатура / Офтальмология / Английские материалы / Dry Eye and Ocular Surface Disorders_Pflugfelder, Beuerman, Elliot Stern_2004

gut sutures. This technique for performing the tarsorrhaphy maintains the normal architecture of the eyelid so that if reversal of the tarsorrhaphy is desired in the future, normal eyelid appearance can be easily obtained.

IV. TRICHIASIS REPAIR

Trichiatic eyelashes are misdirected lashes that can irritate and abrade the ocular surface. The most common cause for trichiasis is chronic inflammation of the ocular surface and eyelid [14]. Although the exact mechanism leading to trichiasis is not known, it is believed that chronic inflammation results in subtle scarring that alters the configuration of the hair shafts, leading to misdirection of the eyelashes. Ocular surface inflammation can also cause posterior lamellar scarring (contracture of the conjunctiva) and cicatricial entropion of the eyelid, resulting in a large number of eyelashes rubbing against the cornea. A single trichiatic lash not only can cause extreme discomfort for patients, but also can lead to significant ocular complications including corneal ulceration and perforation. All patients with ocular irritation or ocular surface disorders should be carefully examined and treated for trichiatic lashes.

Simply epilating the trichiatic lashes can result in temporary relief of ocular irritation. Although many patients are able to perform eyelash epilation on their own, without the benefit of magnification, accidental abrasion of the ocular surface is more likely. Furthermore, recurrence is almost universal after simple eyelash epilation, since the lash follicle remains intact. With more permanent treatments readily available, epilation is generally not considered a good long-term treatment option. Permanent treatments are usually directed toward either destroying or excising the eyelash follicle.

Traditionally, cryoepilation has been the most successful technique for the treatment of aberrant eyelashes. After the area of the trichiatic lashes has been infiltrated with local anesthetic, a cryoprobe is used with nitrous oxide to freeze that

section of the eyelid. A double freeze–thaw technique, achieving temperatures of –20°C during the freeze cycle, has been reported to yield a success rate of 84%

[15].Dermal melanocytes are destroyed at –15°C, however, and a high incidence of eyelid depigmentation can occur after cryoepilation. Cryotherapy also creates a significant amount of eyelid inflammation, which can worsen inflammatory ocular surface disorders such as ocular cicatricial pemphigoid. Postoperative eyelid scarring can also occur with aggressive cryoepilation.

Radiosurgical ablation of the eyelash follicle is the preferred technique of many surgeons treating trichiasis. Using the same device described for punctal occlusion (Fig. 4), radiowaves with a frequency of 3.8 MHz are used to create a localized area of cauterization with minimal collateral damage to adjacent tissues

[16].After the area of the trichiatic lashes has been infiltrated with local anesthetic, an insulated wire is advanced down the eyelash shaft into the follicle

Figure 4 The same radiosurgical device can be used for punctal occlusion and treatment of trichiasis. The needle-tip electrode is well suited for punctal occlusion (A), whereas the insulated wire electrode can be used for treatment of trichiasis (B).

(Fig. 5). The follicle is then cauterized using the minimal amount of energy required to achieve whitening of the eyelid follicle. Each trichiatic lash should be treated individually, and although tedious, this technique results in minimal eyelid scarring and inflammation while still yielding a very high success rate.

Other techniques for treating trichiasis include electrolysis, argon laser ablation, and direct excision of the eyelash follicles [17,18]. Electrolysis has a low success rate and a high rate of complications, including eyelid scarring, destruction of adjacent eyelid structures, and pigmentary changes. Argon laser ablation of eyelash follicles can be effective in thicker, deeply pigmented lashes. For fine or lightly pigmented eyelashes, the laser is relatively ineffective, and overall the success rate is less that that achieved with radiosurgery. Direct excision of the eyelash follicle can be considered when there is a large area of trichiatic eyelashes. However, if marginal or cicatricial entropion is present, correction of the underlying eyelid malposition (see following section) is preferred.

V.EYELID MALPOSITIONS

Eyelid malpositions can result from aging changes to the eyelids and face, from eyelid scarring due to primary ocular surface disorders or eyelid tumors,

Figure 5 The insulated wire electrode is advanced down the eyelash shaft, where precise delivery of energy destroys the eyelash follicle.

or from congenital malformations of the eyelids. The most common eyelid malpositions encountered in patients with dry eyes or ocular surface disorders are entropion, ectropion, and eyelid retraction. With entropion, a large number of eyelashes rotated toward the ocular surface can lead to persistent epithelial defects and corneal ulceration (Fig. 6). Ectropion and eyelid retraction can result in lagophthalmos and exposure keratopathy (Fig. 7).

A variety of techniques are available for correcting eyelid malpositions, depending on the underlying cause. A cicatricial entropion caused by conjunctival scarring and symblepharon formation should be addressed by releasing the cicatrix and, if necessary, reconstructing the posterior lamella with amniotic membrane or a buccal mucous membrane graft [19]. Anterior lamellar resection may also be required if posterior lamellar reconstruction does not correct the entropion adequately. Caution is required when resecting the anterior lamella, however, since this may induce or worsen eyelid retraction. Senile entropion and ectropion are corrected by horizontal tightening of the eyelid. Lower eyelid retractor reinsertion and medial spindle conjunctivoplasty are adjunctive procedures that can also help correct entropic or ectropic eyelids, respectively [20,21].

An effective technique for horizontal eyelid tightening is the lateral tarsal strip procedure [22]. This versatile procedure can be used to help correct

Figure 6 A corneal ulcer has developed in this patient with entropion of the right lower eyelid. The eyelashes along the entire eyelid margin are rotated toward the globe and abrading the ocular surface.

Figure 7 A severe thermal burn to the face has resulted in cicatricial ectropion of the eyelids.

entropion, ectropion, and eyelid retraction. After infiltrating the tissues of the lateral canthus with local anesthetic (2% lidocaine with 1:100,000 epinephrine), a small lateral canthotomy incision is created with scissors. The tarsal strip is fashioned from the lateral eyelid by separating the anterior and posterior lamella, and removing the mucocutaneous junction from the posterior lamella. The palpebral conjunctiva is scraped with a blade to reduce the risk of epithelial inclusion cyst formation. Two interrupted 4–0 polyglactin 910 sutures are used to fixate the tarsal strip to the periosteum of the lateral orbital rim. The canthotomy incision is then closed with several 6–0 plain gut sutures.

Eyelid retraction can be a challenging condition to evaluate and manage because its development occurs slowly over a long period of time. Both upper and lower eyelid retraction can worsen dry eye and ocular irritation symptoms by increasing the interpalpebral distance and causing excessive exposure of the ocular surface. Eyelid retraction can occur in association with conditions such as eyelid scarring, thyroid-related ophthalmopathy, mycosis fungoides, or eyelid skin cancers [23]. Horizontal eyelid tightening with the lateral tarsal strip procedure along with retractor disinsertion (levator recession on the upper eyelid) can reduce the amount of retraction, but more aggressive surgery is often required to fully correct the eyelid retraction [24]. Traditionally, spacer grafts (hard palate, acellular dermis, tarsal graft, donor sclera, or alloplastic implants) and full-thickness skin grafts have been used when horizontal eyelid tightening alone has been inadequate to correct the retracted eyelid [25–31].

For lower eyelids, improved understanding of the anatomic relationship between the midface and the eyelid has led to the use of midface elevation to help correct lower eyelid retraction (Fig. 8). The midface lift has been reported to be a useful procedure to eliminate the inferior tractional forces exacerbating lower eyelid retraction [32]. Through a transconjunctival incision in the inferior fornix of the lower eyelid, the suborbicularis oculi fat pad and the malar fat pad are undermined and elevated off of the maxilla with a flat elevator (Fig. 9). Sharp dissection is minimized to reduce the risk of severing the zygomatico-facial and infraorbital neurovascular structures. Several 4–0 polyglactin 910 sutures on a small semicircle needle are passed through the malar fat pad, engaging the superficial musculoaponeurotic system (SMAS), and elevated supero-temporally. If the sutures are placed too superficially, unacceptable dimpling of the cheeks will result, or if they do not engage the SMAS, inadequate midface elevation will result. The sutures are secured to the periosteum along or inside the orbital rim. The midface lift performed in conjunction with the lateral tarsal strip procedure is capable of correcting lower eyelid retraction for the majority of patients without the need for eyelid spacer grafts or skin grafts.

Figure 8 Midface descent can contribute and exacerbate lower eyelid malpositions. In this patient with severe midfacial descent, lower eyelid ectropion, retraction, and lagophthalmos results in severe ocular surface irritation.

VI. OCULAR SURFACE AND FORNIX RECONSTRUCTION

For patients with ocular surface disorders such as Stevens-Johnson syndrome, ocular cicatricial pemphigoid, and chemical or thermal burns to the ocular surface, the most difficult management issue is not with the acute injury or disease process, but with the long-term effects of subconjunctival fibrosis and ocular surface stem cell loss [3]. Even after multiple attempts at surgical reconstruction, long-term success for the treatment of cicatricial keratoconjunctivitis is difficult to achieve. Over the past several years, ocular surface reconstruction has evolved considerably with the use of amniotic membrane grafting [33–39]. This area of research is advancing rapidly, and it is likely that successful reconstruction of the ocular surface can be achieved in the near future.

Human amniotic membrane is the innermost layer of the placenta, consisting of an acellular basement membrane and an avascular stromal matrix [40]. When grafted to the ocular surface, it provides a matrix that facilitates epithelialization of damaged mucosal surfaces. It has been used to successfully reconstruct corneal and conjunctival surfaces damaged from a broad range of ocular surface disorders. Several studies have shown that the amniotic membrane not only facilitates epithelialization, but also inhibits inflammation, vascularization, and

Figure 9 During a midface lift, the suborbicularis oculi fat pad and the malar fat pad are undermined and elevated off of the maxilla so that the midface can be advanced superiorly to support the lower eyelid.

scarring [33–37]. Human amniotic membrane is now available in a dehydrated form (AmbioDry, OKTO Ophtho, Costa Mesa, CA), which facilitates storage and handling of the graft (Fig. 10).

When using the amniotic membrane for ocular surface reconstruction, proper orientation of the graft is felt to be important by many surgeons. For most applications, the stromal side of the membrane is placed facing down, in contact with the host surgical site. The basement membrane side of the graft should face up, away from the host surgical site. This orientation allows new epithelial cells to grow onto the basement membrane side of the amniotic membrane graft. After achieving the proper orientation, the graft is cut with sharp scissors to the desired size and shape. The graft is then rehydrated with sterile saline solution and secured to the ocular surface with sutures.

The presence of limbal and conjunctival stem cells is vital to the success of ocular surface reconstruction [3]. For example, when severe loss of the limbal stem cells occurs, corneal vascularization and persistent epithelial defects are frequent complications even when an amniotic membrane graft is used. Early results using amniotic membrane with limbal stem cell transplantation have been encouraging, but long-lasting reconstruction has been achieved in less than 50% of patients [41]. In the future, in-vitro cultivation of corneal epithelium from

Figure 10 Dehydrated amniotic membrane can be used for ocular surface reconstruction of the cornea and conjunctiva.

autografts and allografts onto an amniotic membrane may prove to be more successful, as the corneal epithelium will already be expanded on the graft at the time of transplantation. Preliminary reports of these studies have been very encouraging [3].

In cases where there is scarring and destruction of the conjunctival fornices with symblepharon or ankyloblepharon formation, reconstruction with the amniotic membrane often fails (Fig. 11). This is probably due to the loss of conjunctival progenitor cells and the fact that conjunctival epithelial proliferation is relatively slow. While in-vitro cultivation of conjunctival epithelium onto an amniotic membrane may prove to be more successful in the future, the current “gold standard” for reconstruction of the conjunctival fornix is to use a mucous membrane graft [42]. Its success is due mainly to the fact that it already has its own epithelium and does not require the presence of conjunctival stem cells to expand the epithelium onto the graft [43]. The buccal mucous membrane from inside the mouth is a good donor site, since a large graft can be obtained and accessory salivary glands in the graft can provide supplemental ocular surface lubrication.

After all the scarring in the fornix has been released, local anesthetic with epinephrine is infiltrated into the cheek from inside the mouth. The mucosa is then incised with a Bard-Parker #11 blade and the graft is excised as thinly as

Figure 11 After a severe chemical injury, corneal vascularization, obliteration of the upper and lower fornices, symblepharon, and ankyloblepharon have developed. This patient had undergone unsuccessful attempts at ocular surface reconstruction with amniotic membrane alone.

possible with scissors. When harvesting the graft, it is important to identify and avoid Stensen’s duct from the parotid gland (Fig. 12). The donor site is then closed with a running 4–0 chromic gut suture. Removing the submucosal tissues with scissors further thins the mucous membrane graft. The graft is then placed into the eyelid and secured to the surrounding ocular surface with absorbable sutures. A vaulted acrylic conformer is placed behind the eyelids to ensure that the mucous membrane graft is well apposed to and not displaced from the underlying donor site.

VII. SUMMARY

1.Decreased ocular surface lubrication, eyelash and eyelid malpositions, stem cell dysfunction, and cicatricial changes can all contribute to the destruction of the ocular surface.

2.Conservation of natural tears by punctal occlusion can be accomplished temporarily by placement of punctal plugs, or permanently by radiosurgery.

Figure 12 The buccal mucosa from inside the mouth allows a large mucous membrane graft to be harvested for ocular surface reconstruction. Stensen’s duct (arrow) must be avoided when removing the graft.

3.Tarsorrhaphy can narrow the palpebral width and reduce the amount of ocular surface exposed. Botulinum toxin provides a nonsurgical alternative to lateral tarsorrhaphy. It can also treat blepharospasm.

4.Repair of trichiatic eyelashes by cryoepilation is effective, but some inflammation and scarring may result. These side effects are avoided in radiosurgical ablation of the eyelash follicles.

5.A variety of surgical techniques exist to correct eyelid malpositions, depending on the underlying cause.

6.Ocular surface reconstruction has evolved considerably in recent years with the use of amniotic membrane grafting.

REFERENCES

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2.Marsh P, Pflugfelder SC. Topical nonpreserved methylprednisolone therapy for keratoconjunctivitis sicca in Sjögren syndrome. Ophthalmology 1999; 106:811–816.