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Postoperative Management of LASEK

Ahn Nguyen, MD and Amy Scally, OD

Massachusetts Eye and Ear Infirmary

Harvard Medical School

Boston, MA

Dimitri T.Azar, MD

Massachusetts Eye and Ear Infirmary, Schepens Eye Research Institute,

Harvard Medical School

Boston, MA

Alcohol-assisted photorefractive keratectomy (PRK) and laser subepithelial keratomileusis (LASEK) are very similar procedures with a major difference being the preservation of the epithelial flap in LASEK. The postoperative management of LASEK patients is, therefore, not very different from PRK patients. Early on, the goal is to preserve the integrity of the epithelial flap, promote healing, reduce postoperative pain, and minimize complications. In later stages, the focus is on visual recovery, stabilization, and monitoring for development of haze. It is essential that the managing physician recognize the earliest signs of tight lens syndrome, anesthetic abuse, and infectious keratitis throughout the follow-up period to prevent the visually significant sequelae of these complications.

MEDICATIONS

Postoperative eye drops start in the laser room after repositioning of the epithelial flap. The usual combination includes diclofenac sodium 0.1% (Voltaren Ophthalmic; Ciba Vision Ophthalmics, Duluth, GA), ciprofloxacin 0.3% (Ciloxan; Alcon Laboratories, Inc.), and prednisolone acetate 1% (Pred Forte 1%; Allergan America). A bandage contact is then placed on the eye. The Soflens 66 (Bausch & Lomb, Rochester, NY) is commonly used. It is a hydrophilic lens with 66% water and two different base curves, a steep/medium and a flat/medium, able to fit most corneal curvatures thereby minimizing the incidence of epithelial flap loss and contact lens loss in the early postoperative period. Its nonionic material has the potential advantage of not entrapping corneal debris and loose epithelium. Other contact lens choices include the Precision UV (Bausch & Lomb), Sequence (Bausch & Lomb), and Acuvue (Vistakon) lenses. The bandage lenses should remain in place for several days until complete reepithelialization of the corneal surface. Frequent lubrication with preservative-free artificial tears is advised to avoid over-drying of the cornea.

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Table 1. Target Organisms Covered by

Prophylactic Treatment.

The usual postoperative regimen includes topical fluoroquinolone (ciprofloxacin, ofloxacin, or levofloxacin) and steroid (prednisolone acetate 1%) drops 4 times per day for 1 week. The fluoroquinolone is chosen because of its broad spectrum of activity against both Gram-negative and Gram-positive organisms (Tables 1 and 2). The fluoroquinolone is stopped after the first week and the topical steroid is continued twice per day for another week.

Observation Schedule

The follow-up schedule for LASEK patients is similar to PRK patients. The parameters monitored at each visit are the same as those with PRK. Patients are seen on day 1 and day 3 or until complete epithelialization of the surface. They are seen again at 1 week, 1 month, 3 months, 6 months, and 1 year after the procedure. This schedule allows the managing physicians to address any flap-related issues presenting early in the postoperative course as well as any potential late complications.

On the first postoperative day, the visual acuity is assessed and the eye examined. Vision is usually suboptimal from the early surface irregularities. The contact lens should be comfortable, move normally, and be free of deposits. Early recognition of tight lens syndrome may eliminate an unwarranted source of discomfort for patients (Table 3). The overnight wear of contact lenses may cause drying of the corneal surface. This results in

Table 2. Organisms Not Covered by Fluoroquinolone or Aminoglycoside.

Organisms

Fungus

Curvularia (47)

LASEK, PRK, and excimer laser stromal surface ablation 144

Aspergillus flavus (42)

Fusarium solani (46)

Acremonium astrogriseum (48)

Scedosporium apiospermum (49)

Herpes simplex (31)

Enterovirus (41,46)

Table 3. Potential Contact Lens-Related

Complications.

Poor lens fit

Lens loss

Tight lens syndrome

Deposits on contact lens

Hypoxic edema

Sterile subepithelial infiltrates

Toxic keratopathy

Sterile hypopyon

Infectious keratitis

Epithelial abrasion after lens removal

Dry eyes

the contact lens adhering to the corneal surface, limiting lens movement. Patients with decreased endothelial cell counts are especially prone to hypoxia and resulting corneal decompensation when contact lenses are worn overnight. Discontinuing contact lens wear can solve these contact lens-related problems. Under the protective lens, the epithelial surface is usually smooth with only minor disturbances. While many investigators have demonstrated epithelial cells survival after alcohol-assisted debridement (1,2), epithelial cells devitalization may occur after the 20% alcohol exposure. While the cells may appear swollen, gray, and opaque, they will often recover. The presence of folds in the epithelium indicates inadequate adherence, which warrants early lens removal. Identification of any early sign of infection is especially important at this time, because the disturbed epithelium is most prone to colonization by bacteria.

The focus of the second postoperative visit on day 3 is to ascertain complete healing of the epithelium. The contact lens can be removed at this time. Minor irregularities on the surface can be seen after contact lens removal but they are usually inconsequential.

By 1 week, most patients will have recovered relatively good vision because of healing of the ocular surface. Comparative studies of LASEK and PRK have shown that visual recovery in LASEK is faster than PRK. Lee et al. found that 59% of their LASEK patients had recovered an uncorrected vision of 20/25 or better at 1 week and 63% at 1

Postoperative management of LASEK 145

month when compared to 37% of their PRK patients achieving 20/25 or better at 1 week and 56% at 1 month (3,4). Shah et al. observed that their LASEK patients presented with significantly better vision than their PRK patients at all visits during their 62.6 weeks of follow-up (5). In a noncomparative study, Azar et al. showed that 64% of their LASEK patients achieved an uncorrected visual acuity of 20/25 or better at 1 week and 92% at 1 month. Postoperative spherical equivalent of ±0.50 diopter (D) was achieved in 58% of eyes at 1 month and 100% of eyes at 12 months (1). In separate reports, Camellin, Claring-bold, Vinciguerra, and Rouweyha observed the same trend of early visual recovery (6–10). In Rouweyha’s nonrandomized comparative study of LASIK vs. LASEK, it was observed that after the initial slower recovery, LASEK patients do as well as LASIK patients with regard to refractive outcome and stability beyond 1 week. Rouweyha did not demonstrate any overcorrection or undercorrection in either group at 6 months, and 68% of LASEK patients and 72% of LASIK patients were within ±0.50 D of emmetropia at 6 months (10).

At 1 month, almost complete visual recovery is expected. From this stage on, parameters to be followed are vision rehabilitation and haze development. Lee et al. reported lower haze scores in LASEK eyes as compared to PRK at 1 month (3,4). The amount of haze in LASEK eyes peaked at 1 month. By 3 months, the difference in haze scores between the two groups was not statistically significant (3,4). Claringbold and Vinciguerra found that haze was not prevalent after LASEK (8,10). Rouweyha et al. showed visually significant haze accompanied by regression in four of the 46 LASEKtreated eyes (8%) at 6 months (10). This is much lower than the previously reported incidence of haze 6 months after PRK (27). In the eyes with haze, Rouweyha et al. reported difficulty with flap lifting during the procedure (10). It has been speculated that the preserved epithelium protects the ablated surface from the influx of inflammatory mediators theorized to induce haze. Perhaps the flap also minimizes activation of stromal keratocytes and their production of collagen and extracellular matrix (11). Whether the reduced haze is caused by the LASEK procedure itself or by the difference in the laser delivery system (small spot vs. broad beam) remains to be determined.

The suggested advantages of LASEK since its development focus on earlier visual recovery, less pain, and less haze formation as compared with PRK (6,7). Most authorities share this experience (1–5,8,10). However, more recently, a retrospective comparative study between LASEK and PRK by Litwat questioned these potential benefits. The epithelial healing time was longer, pain more prominent, and visual recovery slower in patients who underwent LASEK. The incidence of haze was equal in both groups (12). To date, most LASEK studies have been small and follow-up has been limited; long-term studies are still needed to determine the value of LASEK. Nevertheless, LASEK has been accepted as an alternative to LASIK when the thickness of the cornea is marginal, an alternative that appears to be as good as the more-studied PRK procedure.

Contact Lens Removal

The use of a soft bandage lens is an important feature in post-LASEK patients to minimize pain and promote healing. The protective lens is usually maintained until the epithelium has completely healed and is removed at day 3 to 5 (1,3,4,8). If the lens is lost

LASEK, PRK, and excimer laser stromal surface ablation 146

after the first day, it is usually not replaced. While protective lenses can be of help, they can also be the source of problems for many patients. Prompt recognition of contact lensrelated complications is therefore of utmost importance. Patients need to be closely monitored while their contact lens is in place. Lenses need to be removed at an earlier date if there is evidence of wrinkles and folds in the epithelial flap, which is indicative of irregular epithelial settlement, presence of an infiltrate, or tight lens syndrome in the early postoperative period. Bandage lenses used in refractive surgery have been shown to harbor bacteria leading to postoperative infection (26). Several events can combine to cause tight lens syndrome in refractive patients. Postoperative conjunctival chemosis especially in the presence of alcohol leakage during the procedure, tear stagnation, and lens drying. With the preceding events, the eye is acutely red and painful, the cornea is edematous from hypoxia, and an inflammatory reaction in the anterior chamber may occur. In this setting, an early infectious process must be ruled out. The contact lens is removed and after infectious causes are ruled out, topical steroids may be started (13–15).

Epithelial Defect Management

One of the potential advantages of LASEK over PRK is preservation of the epithelial flap and the resultant faster recovery. If care is taken not to tear the epithelial flap during the procedure, most loose epithelium will settle and adhere by day 3. In Azar’s series, 63% of patients had an epithelial defect on day 1, only 9% on day 3, and no defect observed at 1 week (1). Most authors have also reported a similar time range for epithelial healing (1,3,4,8).

While some authors have reported faster epithelial healing time with LASEK as compared to PRK, others have failed to demonstrate this difference. Lee et al. showed no significant differences in epithelial healing time between the two groups (3,4), while Litwat showed a slower healing time in his LASEK patients as compared to his PRK patients (12).

Claringbold reported small epithelial defects at the time of contact lens removal on day 4. If the bandage contact lens is lost on the first operative day, it is not usually replaced even in the presence of an epithelial defect. Even in patients in whom there was epithelial damage from a dislodged contact lens, the epithelial flap usually heals without any complication (8). Frequent lubrication with preservative free tears and ointment as needed is advised to promote healing. Punctual occlusion can be added if the other measures fail to keep the surface lubricated. Recurrent erosion syndromes after LASEK have only been reported in one study (12).

Pain Management

Pain is still a major issue in the early postoperative period, although it has been suggested that LASEK causes less pain than alcohol-assisted PRK. In a prospective, randomized, comparative study between LASEK and PRK, Lee et al. found that LASEK eyes have statistically significant less pain than PRK eyes. However, they also reported that pain can be quite severe if alcohol leakage occurs during the LASEK procedure (3,4). In Azar’s series of LASEK patients, 47% had no pain in the first postoperative day, only 18% reported pain at day 3, and no reports of pain at 1 week (1). In Camellin’s series, no

Postoperative management of LASEK 147

pain was reported in 44% of patients in the first 24 hours after surgery (6,7). Similarly, only 16.7% of patients in Kornikovsky’s series reported significant pain (16). It is speculated that the preserved epithelial surface acts as an additional protective barrier to an otherwise bare stroma, thus decreasing the incidence of post-LASEK pain. In his study of time course and intensity of pain after PRK, Verma et al. observed that the intensity of pain is maximal at 8 to 10 hours after surgery and usually subsides by 24 hours even in the presence of an epithelial defect (17).

The previous studies suggested that most of the pain control is only needed during the first day after the procedure. Some authors feel that dilute solutions of topical anesthetic can be safely dispensed for a short period of time without potential for abuse. Tutton et al. used topical diclofenac 2 to 5 hours while awake for the first 24 hours to effectively reduce pain without hindering the healing process (18). Topical NSAIDS work through reduction in prostaglandin synthesis that may be increased after excimer laser (18). NSAIDS have also been shown to carry some anesthetic properties (19). Shahinian et al. demonstrated that dilute topical proparacaine 0.05% could be safely used as needed for at least 1 week after surgery to provide pain control (20). Verma et al. used topical tetracaine 1% every half-hour for 24 hours. However, many of his patients reported break-through pain likely caused by the short half-life of tetracaine (17). Cherry found that topical anesthetic, topical diclofenac, and the use of a bandage contact lens have an additive effect in the management of pain after LASEK (21,22). Several patients have been reported at informal meetings whereby dilute topical anesthetic led to anesthetic abuse after LASEK with devastating corneal complications. Accordingly, we feel that although the limited and supervised use of topical anesthetic is probably safe, the risk for corneal toxicity from potential abuse is inherently present.

We routinely give oral percocet 5/325 mg to be taken every 4 hours as needed for pain. In most cases, this regimen was adequate, although patients occasionally reported drowsiness and gastrointestinal upset. We do not use topical nonsteroidal antiinflammatory drugs (NSAIDS) or topical anesthetic.

Infection Prophylaxis and Management

Microbial keratitis after refractive surgery is relatively rare but its sequelae may be devastating. A recent review article on the subject found 41 cases of infectious keratitis after LASIK reported in the literature (23). Estimated incidence varies from 0.1% to 1.2 % (23). Infection rate after PRK is higher because of the lack of epithelium protecting the bare stroma from invasive pathogens. There is no reported incidence of infection after LASEK. In theory, LASEK carries less potential for infection because the epithelial flap is preserved and acts as an effective barrier to infections.

Infections after refractive procedures are usually acquired intraoperatively but may also result from postoperative contamination. The most common causative organisms after refractive surgery are the Gram-positive cocci from the ocular adnexa, (i.e.,

Staphylococcus aureus, Staphylococcus epidermitis, Streptococcus viridans, Streptococcus pneumoniae) (23). Studies of early infectious keratitis after LASIK showed that the mean onset was 5.3±6 days after surgery (25). Patients present with acute onset of pain and with decreased vision. Late-onset infections have been shown to occur

LASEK, PRK, and excimer laser stromal surface ablation 148

up to 3 months after surgery (25). Onset of PRK-associated infection is also early because most of the inoculation occurs while the epithelium is still healing.

The best treatment is prevention. Measures can be taken during the preoperative, intraoperative, and postoperative period. Preoperative predisposing factors should be identified and addressed, including blepharitis, meibomitis, dry eye conditions, and immunosuppressive states. Intraoperative measures include sterile techniques, a good lid scrub with betadine, careful draping of the lid margin and lashes, and avoiding excessive manipulation of the epithelial flap. Epithelial defects, delayed epithelialization, and topical corticosteroid use are additional risk factors in the postoperative period. The protective lens used also carries the potential risk of contamination. Staphylococcus epidermitis has been cultured from soft contact lenses used in patients after refractive procedures (26). Patients are routinely given a prophylactic fluoroquinilone four times per day for 1 week or until epithelial healing is complete. Fluoroquinolone has a broadspectrum activity covering most Gram-negative and some Gram-positive organisms.

Management of infectious keratitis after refractive procedures is similar to that for bacterial keratitis not related to refractive procedures. Corneal infiltrates after LASEK usually start in the epithelium and may be easier to manage than an infiltrate located under a LASIK flap. The size of the infiltrate and the epithelial defect should be recorded to allow comparison on follow-up examinations. Scraping of the infiltrate is done before starting empiric treatment. Scraping samples are inoculated on chocolate, blood, and Sabouraud’s agar, along with thioglycolate broth. Plates are also sent for Gram and Giemsa stain. Empiric treatment is started with a broad-spectrum antibiotic, either a combination of fortified cefazolin (133 mg/mL) and fortified tobramycin (14 mg/mL) or monotherapy with a fluoroquinolone on an hourly basis. Adjustment is made according to clinical response and culture sensitivity. Topical cyclopentolate 1% or atropine 1% can be used twice per day to prevent posterior synechiae formation. The use of topical corticosteroids is controversial and probably should not be started until the pathogen is identified and a clinical response to treatment is documented.

Prevention is still much better than having to manage the complications after surgery. Early detection and treatment may improve the final outcome.

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