Post-LASIK infection can threaten a patient’s sight

Surgeons should be familiar with risk factors, symptoms and treatments of keratitis that present after LASIK.

Issue: August 1, 2006

ByAmar Agarwal, MS, FRCS, FRCOphth

BySoosan Jacob, MS, FRCS, DNB

ByNibaran Gangopadhyay, MS

LASIK has become a common refractive procedure and is generally considered safe. The incidence of sight-threatening complications after LASIK remains low.

However post-LASIK infections can be a disastrous complication for the patient who is often just undergoing a cosmetic procedure and usually has high expectations (Figure 1). Other refractive surgeries, such as radial keratotomy and hexagonal keratotomy, have been associated with infections in the past. There have also been reports of endophthalmitis after incisional refractive surgery.

Risk factors

Infection occurring after photorefractive keratectomy (PRK) may be secondary to the defect in the epithelium (Figure 2) as well as the use of therapeutic contact lenses. Unlike PRK, the integrity of Bowman’s membrane and the corneal epithelium is maintained intact after LASIK; hence, the risk of microbial keratitis after LASIK is considered lower than other procedures.

Despite this, the occurrence of keratitis after LASIK is a reality, and numerous case reports testify this. During surgery, the corneal stroma may come into contact with infectious agents coming from the patient’s own body or from contaminants present on the instruments. The surgeon and the operating room may also act as a source. Breaks in the epithelial barrier and excessive surgical manipulation are other risk factors. Other factors in the postoperative period, such as delayed postoperative re-epithelialization of the cornea, the use of topical steroids and therapeutic contact lenses as well as decreased corneal sensitivity and dry eye, can all contribute to post-LASIK infections.

Clinical signs and symptoms

Infectious keratitis generally presents later than diffuse lamellar keratitis, with which it is often confused. It traditionally presents at least 1 week after surgery and often months later.

Amar Agarwal

Fungal keratitis usually has a late onset (2 weeks after surgery), although Staphylococcus epidermidis and Mycobacterium may also present late. A focal area of infiltrate associated with diffuse or localized inflammation, which may extend throughout the corneal thickness, is generally seen. It may extend into the untreated area of the cornea and outside the flap. The flap may begin to melt. There may be associated ciliary congestion, secondary iritis, hypopyon and secondary glaucoma. There is a loss in best corrected visual acuity and uncorrected visual acuity. The patient may have symptoms such as pain, irritation, lacrimation or photophobia. Atypical organisms such as fungi and mycobacteria often are responsible, and there may therefore be no response to the usual antimicrobial therapy. Simultaneous or sequential bilateral involvement of both eyes and infection after flap lift enhancement have also been described.

Infectious post-LASIK keratitis also has to be differentiated from sterile corneal infiltrates, which have been described after PRK and LASIK. Sterile infiltrates also present with symptoms similar to infectious keratitis. Subepithelial white infiltrates, which may be associated with immune rings, are seen in the first few postoperative days. Smears and cultures are negative, and the infiltrate responds to topical steroids. It may result in stromal scarring and loss of BCVA. Numerous etiologies have been proposed for this, including staphylococcal-immune mediation, secondary to the use of topical NSAIDs without concomitant use of topical steroids and contact-lens-induced hypoxia.

Complications

The infection can spread to involve all layers of the cornea and can cause flap and stromal melting and scarring, anterior chamber reaction, hypopyon, secondary glaucoma, anterior and posterior synechiae, irregular astigmatism, and loss of BCVA and UCVA.

Prevention

It is important to take every possible measure to prevent this sight-threatening complication. Preoperative evaluation of the adnexa and the lacrimal apparatus and treatment of any existing condition should become routine for all LASIK patients, just as it is for cataract surgery. Some surgeons advocate performing surgery in only one eye at a time or using different instrument sets for the two eyes in case of simultaneous bilateral procedures. It is highly advisable to maintain rigid asepsis throughout the surgical procedure, including the use of sterile drapes.

Good sterilization techniques can prevent the use of contaminated instruments. Povidone-iodine solution should be used to paint the lids preoperatively. All fluids applied to the eye before, during and after LASIK should be sterile, as atypical mycobacteria epidemics have been traced to originate from the use of nonsterile water used to clean instruments or from the ice used during LASIK.

Corneal ulcer with hypopyon after LASIK.	Corneal defect staining with fluorescein.
Status post-penetrating keratoplasty.	Reinfection with hypopyon after penetrating keratoplasty.
Images: Agarwal A and colleagues

Treatment

Early diagnosis and institution of appropriate therapy is of prime importance in the treatment of post-LASIK infections. Any focal infiltrate should be considered infectious until proven otherwise. Flap elevation and culturing should be performed as early as possible in all cases in which post-LASIK infectious keratitis is suspected. Smears help in deciding on immediate treatment, which is then changed according to the culture and sensitivity reports. Polymerase chain reaction testing is also helpful in diagnosis. A corneal biopsy may be required in some cases. Empiric therapy is not helpful, as opportunistic and atypical organisms with unusual antimicrobial sensitivities are common and these do not respond to conventional therapy.

One can do elevation of the flap, culture and irrigation of the stromal bed with antibiotic solution (fortified vancomycin 50 mg/mL for rapid-onset keratitis and fortified amikacin 35 mg/mL for delayed-onset keratitis) for all post-LASIK infectious keratitis.

For rapid-onset keratitis, it is recommended to use a fourth-generation topical fluoroquinolone such as gatifloxacin 0.3% or moxifloxacin 0.5% given in a loading dose every 5 minutes for three doses and then every 30 minutes, alternating with an antimicrobial that is rapidly bactericidal and has increased activity against gram-positive organisms, such as fortified cefazolin 50 mg/mL every 30 minutes. In patients in a hospital environment who face added risk of methicillin-resistant Staphylococcus aureus (MRSA), it is recommended to substitute fortified vancomycin 50 mg/mL for cefazolin every 30 minutes to provide more effective therapy against MRSA. Oral doxycycline 100 mg twice a day to inhibit collagenase production and discontinuation of corticosteroids is also advised. Treatment should be modified according to culture and sensitivity reports.

For delayed-onset keratitis, which is commonly due to atypical mycobacteria, nocardia and fungi, it is recommended to begin therapy with amikacin 35 mg/mL every 30 minutes, alternating with gatifloxacin 0.3% or moxifloxacin 0.5% every 30 minutes along with oral doxycycline 100 mg twice a day and discontinuation of corticosteroids.

This treatment is ineffective for fungal infections that often present late with more extensive keratitis. Appropriate antifungal agents should be started and modified according to sensitivity reports. Fungal infections are often difficult to treat because of the lack of potent antifungal agents, low penetration through intact corneal epithelium, ocular toxicity and decreased solubility.

The flap may often need to be amputated for better penetration of the antifungal agents. In unresponsive cases with extensive involvement of the cornea, a penetrating keratoplasty may often become necessary (Figures 3 and 4). Polymerase chain reaction testing can be used to diagnose the causative organism, especially in cases with limited availability of samples. Confocal microscopy can also be used.

For More Information:

Amar Agarwal, MS, FRCS, FRCOphth is director of Dr. Agarwal’s Group of Eye Hospitals. Dr. Agarwal is author of several books published by SLACK, Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery, and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; fax: 91-44-28115871; e-mail: dragarwal@vsnl.com; Web site: www.dragarwal.com.

References:

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Donnenfeld ED, Kim T, et al. ASCRS White Paper: Management of infectious keratitis following laser in situ keratomileusis. J Cataract Refract Surg. 2005;31(10):2008-11.

Duffey RJ. Bilateral Serratia marcescens keratitis after simultaneous bilateral radial keratotomy. Am J Ophthalmol. 1995;119(2):233-236.

Jain S, Azar DT. Eye infections after refractive keratotomy. J Refract Surg. 1996;12(1):148-155.

Rashid ER, Waring GO III. Complications of radial and transverse keratotomy. Surv Ophthalmol. 1989;34(2):73-106.

Szerenyi K, McDonnell JM, et al. Keratitis as a complication of bilateral, simultaneous radial keratotomy. Am J Ophthalmol. 1994;117(4):462-467.