Corneal Interface Abscess after Excimer Laser in situ Keratomileusis

Laser in-situ keratomileusis infection: review and update of current practices

PURPOSE OF REVIEW

To review new clinically relevant data regarding the prevention cause and treatment of laser in-situ keratomileusis (LASIK) infections.

RECENT FINDINGS

Many recent studies of post-LASIK infectious keratitis show the predominance of atypical mycobacteria and Gram-positive cocci and the growing number of other rare pathogens. The American Society of Cataract and Refractive Surgery White Paper treatment paradigm remains the model for initial treatment of LASIK-associated infectious keratitis.

SUMMARY

Improved understanding of the risk factor, different causes, along with a high degree of suspicion on initial presentation is crucial in order to provide the appropriate management in LASIK-associated infectious keratitis.

Unilateral Candida parapsilosis interface keratitis after laser in situ keratomileusis: case report and review of the literature

PURPOSE

To describe a rare case of early-onset Candida parapsilosis infection after laser in situ keratomileusis (LASIK) and review the published reports of post-LASIK fungal infections.

METHODS

A 32-year-old woman presented with interface infiltration in the central interface in the right eye 2 days after LASIK surgery. The right eye flap was lifted, and the opacities were scraped. Two days later, a 3- x 3-mm-dense oval opacity and diffuse hazes were noted. Surgical intervention was arranged because of suspicion of interface infectious keratitis.

RESULTS

After an apparent post-LASIK keratitis with related interface inflammation failed to respond to medical therapy, corneal culture results were positive for C. parapsilosis 2 weeks 6 days after presentation. The patient was started on topical drops of amphotericin B 0.15% every hour after the smear showed the presence of yeast. The opacities decreased, and the topical antifungal drops were tapered. One month later, her uncorrected visual acuity recovered to 20/20.

CONCLUSIONS

Candida parapsilosis interface keratitis after LASIK may occur in the early phase. Early diagnosis and proper treatment can result in good outcome.

Infectious and noninfectious keratitis after laser in situ keratomileusis

PURPOSE

To retrospectively review the occurrence, treatment, and visual outcomes associated with various etiologies of keratitis as a postoperative complication of laser in situ keratomileusis (LASIK) at an academic surgical center.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

METHODS

The charts of 5618 post-LASIK patients (10 477 eyes) were reviewed for the development of keratitis. Occurrence rates, management regimens, and final best spectacle-corrected visual acuity (BSCVA) were reported for infectious and noninfectious keratitis etiologies.

RESULTS

Post-LASIK keratitis was diagnosed in 279 eyes. The keratitis was diagnosed as infectious in 33 eyes (12%) and as noninfectious in 246 eyes (88%). Infectious cases included 5 eyes (15%) with herpes simplex keratitis (HSV), 18 (55%) with adenoviral keratitis, and 10 (30%) with nonviral (including bacterial, fungal, and parasitic) keratitis. Of noninfectious cases, 193 (78%) were classified as diffuse lamellar keratitis (DLK), 36 (15%) as staphylococcal marginal hypersensitivity, and 17 (15%) as localized debris-related keratitis.

CONCLUSIONS

The occurrence of post-LASIK keratitis was 2.66%, with DLK being the most common diagnosis overall. The occurrence of noninfectious keratitis (2.34%) was 7.5 times greater than the occurrence of infectious keratitis (0.31%). Adenoviral keratitis had the best visual outcomes overall, with all 18 patients achieving 20/20 BSCVA. In contrast, all 5 eyes with HSV keratitis lost 1 or 2 lines of BSCVA. Excluding adenoviral keratitis, infectious etiologies had significantly worse visual outcomes than noninfectious etiologies at the 20/40 and 20/20 levels (P = .0013 and P<.001, respectively).

Management of a post-ELLKAT keratectasia with a gas permeable contact lens

BACKGROUND

The Excimer laser keratoplasty of augmented thickness for keratoconus (ELLKAT) has been proposed for the refractive management of keratoconus.

CASE REPORT

A 41-year-old man with a history of bilateral keratoconus came to the clinic for a contact lens. He had undergone an ELLKAT procedure in his right eye some months earlier in an attempt to obtain acceptable unaided vision. As the result in this eye was not positive, the surgery in the fellow eye was cancelled. On examination, I diagnosed a centrally located keratectasia (KE) in his RE. After surgery, the corneal shape presented some complications in relation to contact lens fitting. The patient was able to achieve 6/9.6 acuity with adequate comfort with a Soper lens using a "modified three-point touch" relationship.

CONCLUSIONS

The surgical procedure of ELLKAT can exhibit some advantages with regard to the penetrating keratoplasty. In this case, because a keratectasia was induced, a contact lens fitting was needed to restore vision. A gas permeable contact lens with a Soper design and with a "modified three-point touch" fitting was a viable clinical solution. The fitting of contact lenses in cases of keratectasia can be a practical solution that may avoid the need for further surgery.

Unusual anaerobic bacteria in keratitis after laser in situ keratomileusis

Laser in situ keratomileusis (LASIK) was performed in the left eye of a 57-year-old man for residual ametropia after phacoemulsification. The patient was given topical tobramycin and a corticosteroid for 1 week postoperatively. Fifteen days later, he developed 3 corneal infiltrates beneath the flap with a gas bubble, suggesting an anaerobic infection. Tobramycin and ofloxacin were administered every 2 hours, but the condition worsened. Corneal scrapings were taken from beneath the flap for microbiological cultures and a polymerase chain reaction (PCR) test. The PCR amplification was negative for fungi and mycobacteria and positive for bacterial DNA. Sequence analysis showed Propionibacterium granulosum as the causal agent, but cultures were negative. Treatment with vancomycin and cefazolin led to clinical improvement, with resolution of corneal infiltrates. Anaerobic microorganisms can cause keratitis after LASIK. Polymerase chain reaction amplification and DNA typing can help detect microorganisms involved in these ocular infections.

Infections following laser in situ keratomileusis: an integration of the published literature

Infections occurring after laser in situ keratomileusis (LASIK) surgery are uncommon, but the number of reports have steadily increased in recent years. This systematic, comprehensive review and analysis of the published literature has been performed in order to develop an integrative perspective on these infections. We have stratified the data by potential associations, microbiology, treatment, and the degree of visual loss, using Fisher's exact tests and Student's t-tests for analysis. In this review, we found that Gram-positive bacteria and mycobacterium were the most common causative organisms. Type of postoperative antibiotic and steroid use was not associated with particular infecting organisms or severity of visual loss. Gram-positive infections were more likely to present less than 7 days after LASIK, and they were associated with pain, discharge, epithelial defects, and anterior chamber reactions. Fungal infections were associated with redness and tearing on presentation. Mycobacterial infections were more likely to present 10 or more days after LASIK surgery. Moderate or severe visual reductions in visual acuity occurred in 49.4% of eyes. Severe reductions in visual acuity were significantly more associated with fungal infections. Flap lift and repositioning preformed within 3 days of symptom onset may be associated with better visual outcome.

Ulcerative keratitis caused by Serratia marcescens after laser in situ keratomileusis

We report 2 cases of severe corneal infections caused by Serratia marcescens after laser in situ keratomileusis (LASIK). Twenty-four hours after LASIK, 2 patients developed infectious keratitis, 1 bilaterally. In each eye, the corneal flap was edematous, ulcerated, and detached from the stromal bed. Treatment included removal of the necrotic flap and aggressive antibiotic therapy. Cultures from corneal exudates were positive for S marcescens. After 1 year, both patients had a loss of best corrected visual acuity (BCVA) ranging from 20/40 to 20/22 because of irregular astigmatism. Overrefraction with a hard contact lens resulted in a BCVA of 20/20 in the 3 affected eyes. Slitlamp examination showed trace subepithelial haze without severe corneal scarring. Videokeratography disclosed areas of paracentral inferior steepening resembling keratoconus. Refraction and videokeratography remained stable after 6 months of follow-up. Ulcerative keratitis caused by S marcescens is a potential complication of LASIK. Bilateral involvement may occur if bilateral simultaneous surgery is performed.

Recurrent interface infiltration with hypopyon after astigmatic laser in situ keratomileusis on a penetrating corneal graft

A 56-year-old woman was referred with recurrent interface infiltration and hypopyon after astigmatic laser in situ keratomileusis (LASIK) on a corneal graft. Pseudomonas aeruginosa was isolated as the causative pathogen. Penetrating keratoplasty had been performed 2 years before refractive surgery. After the antibiotic medication was tapered, 3 recurrences of interface infiltration with hypopyon were observed. Penetrating rekeratoplasty was deemed appropriate. Histological examination of the explanted corneal graft revealed anterior stromal neutrophil infiltration. This case illustrates that microbial pathogens brought underneath the flap by LASIK can persist months later despite antimicrobial treatment.

Infectious keratitis after laser in situ keratomileusis: Results of an ASCRS survey

To investigate the incidence, culture results, treatment, and visual outcomes of infectious keratitis after laser in situ keratomileusis (LASIK) worldwide, the Cornea Clinical Committee of the American Society of Cataract and Refractive Surgery (ASCRS) contacted 8600 United States and international ASCRS members by e-mail and asked them to respond to a questionnaire about post-LASIK infectious keratitis. One hundred sixteen infections were reported by 56 LASIK surgeons who had performed an estimated 338 550 procedures. Seventy-six cases presented in the first week after surgery, 7 during the second week, 17 between the second and fourth weeks, and 16 after 1 month. Forty-seven cases were not diagnosed on initial presentation. The most common organisms cultured were atypical mycobacteria and staphylococci. Empiric therapy is not recommended as most of the organisms are opportunistic and not responsive to conventional therapy. Flap elevation and culturing should be performed when post-LASIK infectious keratitis is suspected.

Infectious keratitis after photorefractive keratectomy

PURPOSE

To elucidate risk factors, microbial culture results, and visual outcomes for infectious keratitis after photorefractive keratectomy (PRK).

DESIGN

Multicenter, retrospective chart review, case report, and literature review.

METHODS

The records of 12 patients with infectious keratitis after PRK were reviewed.

MAIN OUTCOME MEASURES

Causative organism, response to medical treatment, and visual outcome.

RESULTS

Infectious keratitis developed in 13 eyes of 12 patients after PRK. Organisms cultured were Staphylococcus aureus (n = 5), including a bilateral case of methicillin-resistant Staphylococcus aureus; Staphylococcus epidermidis (n = 4); Streptococcus pneumoniae (n = 3); and Streptococcus viridans (n = 1). Four patients manipulated their contact lenses, and 2 patients were exposed to nosocomial organisms while working in a hospital environment. Prophylactic antibiotics used were tobramycin (nine cases), polymyxin B-trimethoprim (three cases), and ciprofloxacin (one case). Final best spectacle-corrected visual acuity ranged from 20/20 to 20/100.

CONCLUSIONS

Infectious corneal ulceration is a serious potential complication of PRK. Gram-positive organisms are the most common pathogens. Antibiotic prophylaxis should be broad spectrum and should include gram-positive coverage.

Bilateral Marginal Sterile Infiltrates and Diffuse Lamellar Keratitis After Laser in situ Keratomileusis

PURPOSE

To report cases of acute bilateral catarrhal infiltrates in the early postoperative period after laser in situ keratomileusis (LASIK).

METHODS

Retrospective review of both eyes of two patients.

RESULTS

Two patients developed acute bilateral, marginal, catarrhal infiltrates in the early postoperative period after LASIK. Both patients had moderate to severe chronic meibomian gland dysfunction preoperatively. One patient (both eyes) developed grade 3 diffuse lamellar keratitis (DLK) that required both flaps to be lifted for irrigation and cleaning on postoperative day 5. Fungal and bacterial cultures were negative in both eyes of both patients. The condition resolved with intensive topical corticosteroids and fortified antibiotics. Regression of refractive error and the need for enhancement was encountered in all eyes. There was mild recurrence in one eye of each patient with pretreatment with topical corticosteroids prior to enhancement.

CONCLUSIONS

Endogenous factors such as chronic blepharitis and meibomian gland dysfunction may trigger inflammation resulting in sporadic cases of catarrhal infiltrates after LASIK. These patients may have chronic inflammatory milieus that can trigger sporadic cases of catarrhal infiltrates after LASIK, with accompanying diffuse lamellar keratitis.

A controlled trial of povidone-iodine to treat infectious conjunctivitis in children

PURPOSE

To report the efficacy of povidone-iodine as a treatment for conjunctivitis in pediatric patients.

DESIGN

Double-masked, controlled, prospective clinical trial.

METHODS

In an ophthalmology clinic in a general hospital in Manila, Philippines, 459 children (mean [SD] age 6.6 [6.6] years; range, 7 months-21 years) with acute conjunctivitis were studied. Infected eyes were cultured for bacteria and underwent immunofluorescent testing for Chlamydia trachomatis. Viral conjunctivitis was diagnosed if bacterial cultures were negative and diagnostic criteria were met. Subjects were alternated to receive povidone-iodine 1.25% or neomycin-polymyxin-B-gramicidin ophthalmic solution, one drop 4 times daily in the affected eye. Ocular inflammation was evaluated daily by the family or patient and weekly by an ophthalmologist. The main outcome measures were days until cured and proportion cured after 1 and 2 weeks of treatment.

RESULTS

Despite adequate statistical power (power >80% for a 1-day difference and P <.05), there was no significant difference between treatment groups regarding the number of days to cure or proportion cured at 1 or 2 weeks whether caused by bacteria or virus (P =.133-.824 for the four comparisons). After 1 week of treatment, povidone-iodine cured marginally more chlamydial infections than the antibiotic (P =.057). By 2 weeks, fewer chlamydial infections were cured than those of viral or bacterial etiology (P =.0001). The younger the patient, the faster their conjunctivitis resolved (R = 0.13, P =.013).

CONCLUSIONS

Povidone-iodine 1.25% ophthalmic solution was as effective as neomycin-polymyxin B-gramicidin for treating bacterial conjunctivitis, somewhat more effective against chlamydia, and as ineffective against viral conjunctivitis. Povidone-iodine ophthalmic solution should be strongly considered as treatment for bacterial and chlamydial conjunctivitis, especially in developing countries where topical antibiotics are often unavailable or costly.

Interface fungal infection after laser in situ keratomileusis presenting as diffuse lamellar keratitis. A clinicopathological report

PURPOSE

To report clinicopathological analyses of 3 cases of interface fungal infection following laser in situ keratomileusis (LASIK) and diffuse lamellar keratitis (DLK).

SETTING

Center for Research on Ocular Therapeutics and Biodevices and Arthur and Holly Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Clinicopathological analysis of 5 eyes of 3 patients who developed culture-proven interface fungal infection after LASIK was performed. Detailed pathological analysis of the amputated flap from 1 case included light, scanning, and transmission electron microscopy.

RESULTS

Culture and pathological analysis revealed Candida albicans in all 3 cases. Common links among the cases were early onset of DLK following intensive corticosteroid and antibiotic treatment and later onset of interface fungal infection. All cases resolved, and good visual acuity was restored after medical treatment with antifungal agents.

CONCLUSIONS

Interface fungal infection after LASIK can be sight-threatening. Early lifting of the flap, fungal culture, and aggressive antifungal treatment are required to treat this complication and avoid deleterious sequelae.

Microbial Keratitis After Laser in situ Keratomileusis

PURPOSE AND METHOD

To review the literature on microbial keratitis reported after laser in situ keratomileusis (LASIK).

RESULTS

Forty-one eyes have been reported to have microbial keratitis after LASIK. The causative organisms vary from gram positive bacteria to atypical mycobacteria, fungal, and viral pathogens. The infection is usually acquired intraoperatively, but may also be caused by postoperative contamination. A majority of the patients present within 72 hours of the surgery with an acute onset of symptoms. Management of microbial keratitis after LASIK includes aggressive topical fortified antibiotic therapy, irrigation of stromal bed with antibiotic solution after lifting the flap, and sending the scraping of the infiltrate for microbiological evaluation. The keratitis heals with scarring and a best spectacle-corrected visual acuity of 20/40 or better can be obtained in the majority of the patients.

CONCLUSION

Microbial keratitis is a sight-threatening complication of LASIK.

A Cluster of cases of Mycobacterium szulgai keratitis that occurred after laser-assisted in situ keratomileusis

Laser-assisted in situ keratomileusis (LASIK) is a recently developed ophthalmic procedure. When 2 patients developed keratitis caused by Mycobacterium szulgai after they underwent LASIK surgery, we conducted a retrospective cohort study of all LASIK procedures performed at Scott & White Clinic (Temple, Texas) during a 4.5-month period. Seven patients had compatible symptoms and signs, 5 of whom had confirmed M. szulgai keratitis. Five cases occurred among 30 procedures performed by doctor A, and there were no cases among 62 procedures performed by doctor B (approximate relative risk, 12.0; 95% confidence interval, 1.6-679.0; P=.0029). Doctor A had chilled syringes of saline solution in ice for intraoperative lavage-the only factor that differentiated the procedures of the 2 surgeons. Cultures of samples from the source ice machine's drain identified M. szulgai; the strain was identical to isolates recovered from all confirmed cases and differed from 4 standard M. szulgai strains, as determined by pulsed-field gel electrophoresis. Intraoperative contamination from ice water apparently led to M. szulgai keratitis in these patients.

Laser in situ keratomileusis for myopia and astigmatism: safety and efficacy: a report by the American Academy of Ophthalmology

OBJECTIVE

This document describes laser in situ keratomileusis (LASIK) for myopia and astigmatism and examines the evidence to answer key questions about the efficacy and safety of the procedure.

METHODS

A literature search conducted for the years 1968 to 2000 retrieved 486 citations and an update search conducted in June 2001 yielded an additional 243 articles. The panel members reviewed 160 of these articles and selected 47 for the panel methodologist to review and rate according to the strength of evidence. A Level I rating is assigned to properly conducted, well-designed, randomized clinical trials; a Level II rating is assigned to well-designed cohort and case-control studies; and a Level III rating is assigned to case series and poorly designed prospective and retrospective studies, including case-control studies.

RESULTS

The assessment describes randomized controlled trials published in 1997 or later (Level I evidence) and more recent comparative and noncomparative case series (Level II and Level III evidence), focusing on results for safety and effectiveness. It is difficult to extrapolate results from these studies that are comparable to current practices with the most recent generation lasers because of the rapid evolution of LASIK technology and techniques. It is also difficult to compare studies because of variations in the range of preoperative myopia, follow-up periods, lasers, nomograms, microkeratomes and techniques, the time frame of the study, and the investigators' experience.

CONCLUSIONS

For low to moderate myopia, results from studies in the literature have shown that LASIK is effective and predictable in terms of obtaining very good to excellent uncorrected visual acuity and that it is safe in terms of minimal loss of visual acuity. For moderate to high myopia (>6.0 D), the results are more variable, given the wide range of preoperative myopia. The results are similar for treated eyes with mild to moderate degrees of astigmatism (<2.0 D). Serious adverse complications leading to significant permanent visual loss such as infections and corneal ectasia probably occur rarely in LASIK procedures; however, side effects such as dry eyes, night time starbursts, and reduced contrast sensitivity occur relatively frequently. There were insufficient data in prospective, comparative trials to describe the relative advantages and disadvantages of different lasers or nomograms.

Interface fluid after laser in situ keratomileusis

We report a case in which raised intraocular pressure (IOP) was associated with interface fluid after uneventful bilateral laser in situ keratomileusis (LASIK). The patient presented with diffuse lamellar keratitis in both eyes 3 weeks postoperatively that was treated aggressively with topical corticosteroids. A steroid-induced rise in IOP resulted in interface fluid accumulation and microcystic edema. Measurements with the Goldmann tonometer revealed an IOP of 3.0 mm Hg in both eyes. However, Schiotz tonometry recorded a pressure of 54.7 mm Hg in both eyes. Reduction in the dosage of topical corticosteroid and medical treatment of the raised IOP resulted in resolution of the microcystic edema and interface fluid accumulation. This case highlights the inaccuracies of IOP measurement after LASIK and the resulting complications.

Complications of Laser in situ Keratomileusis: Etiology, Prevention, and Treatment

PURPOSE

To review the etiology, prevention, and management of laser in situ keratomileusis (LASIK) complications.

METHODS

Review of literature and the experience of the authors.

RESULTS

Careful preoperative screening is critical to prevention of many potential complications of LASIK. Flap complications that occur during surgery are typically managed by replacement of the flap and repeating the surgery or applying special methods such as transepithelial photorefractive keratectomy weeks to months following the initial procedure. A common source of serious complications is the use of a microkeratome that functions after improper assembly. Timely treatment of postoperative complications such as diffuse lamellar keratitis, flap striae, and infection is critical to an optimal outcome.

CONCLUSION

Most complications of LASIK can be treated effectively and have minimal effect on the final outcome after surgery, if appropriate methods are used for management.

Interface Fluid and Diffuse Corneal Edema After Laser in situ Keratomileusis

PURPOSE

To report a new complication of interface fluid accumulation and corneal edema in an uneventful laser in situ keratomileusis (LASIK) procedure.

METHODS

Uncomplicated bilateral LASIK for myopia using the Hansatome microkeratome was performed. One day postoperatively, the patient noted decreased visual acuity. The topical corticosteroid was changed from dexamethasone to prednisolone acetate 1% every 2 hours. Two weeks later the patient reported worsening visual acuity in both eyes. Uncorrected visual acuity was 20/200 in the right eye and 20/100 in the left. Slit-lamp biomicroscopy indicated significant fluid build-up in the interface. Intraocular pressure (IOP) by Goldmann applanation tonometry was 15 mmHg in the right eye and 14 mmHg in the left.

RESULTS

After 4 weeks, intraocular pressure by bidigital pressure was increased and high. The corticosteroid was discontinued and antiglaucoma medication lowered the intraocular pressure, which resulted in corneal clearing and disappearence of interface fluid in both eyes.

CONCLUSIONS

Early recognition of this new complication of LASIK is necessary. The falsely low reading of IOP in the setting of interface fluid was the result of easy compressibility of the fluid-filled space and reflects the pressure of the interface fluid. This apparently low IOP reading can be an additional sign of the existence of interface fluid. The corticosteroid should be discontinued and antiglaucoma medication instituted. This should lead to a lowering of intraocular pressure and result in corneal clearing and disappearence of the interface fluid with improvement in visual acuity.

Diffuse Lamellar Keratitis Induced by Trauma 6 Months After Laser in situ Keratomileusis

This case report illustrates an unusual presentation of diffuse lamellar keratitis triggered by a foreign body striking the eye 6 months after laser in situ keratomileusis (LASIK). The etiology of diffuse lamellar keratitis is unclear. The infiltrate within the plane of the flap after removal of the foreign body supports the theory that diffuse lamellar keratitis is an inflammatory reaction.

Postoperative Inflammation, Microbial Complications, and Wound Healing Following Laser in situ Keratomileusis

Although the biology of corneal wound healing is only partly understood, healing after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) differs in many respects, and the mechanisms appear to be differently controlled. There is less of an inflammatory and healing response after LASIK, but a longer period of sensory denervation. The cellular, molecular, and neural regulatory phenomena associated with postoperative inflammation and wound healing are likely to be involved in the adverse effects after LASIK, such as flap melt, epithelial ingrowth, and regression. Interface opacities in the early postoperative period include diffuse lamellar keratitis (DLK), microbial keratitis, epithelial cells, and interface opacities. Diffuse lamellar keratitis (sands of the Sahara syndrome) describes an apparently noninfectious diffuse interface inflammation after lamellar corneal surgery probably caused by an allergic or a toxic inflammatory reaction. Noninfectious keratitis must be distinguished from microbial keratitis to avoid aggressive management and treatment with antimicrobial drugs. Microbial keratitis is a serious complication after LASIK, but a good visual outcome can be achieved following prompt and appropriate treatment.

Postoperative complications in laser in situ keratomileusis

Laser in situ keratomileusis (LASIK) has become the most common procedure to correct refractive errors in North America. Increasing numbers of patients and surgeons are choosing LASIK in the management of low and moderate myopia, astigmatism, and hyperopia. LASIK presents a unique group of postoperative challenges and complications. It is important to be able to identify these complications in the early and late postoperative periods and to provide effective management. In this article, we review the most commonly encountered early and late postoperative complications after LASIK and the most current methods in prevention and treatment.

The effectiveness of a topical antibiotic irrigating solution in a model of staphylococcal keratitis after lamellar keratectomy

PURPOSE

To create a model of Staphylococcus aureus keratitis after lamellar keratectomy; to assess the toxicity of an antibiotic irrigating solution on the corneal stromal bed; and to test the chemotherapeutic effectiveness of a topical antibiotic, both alone and with an antibiotic-containing irrigating solution in preventing S. aureus keratitis after lamellar keratectomy.

METHODS

The right eye of each of 38 rabbits were used in this study. In 18 eyes, a lamellar flap was created with a microkeratome, and an inoculum of S. aureus (either 1,000, 5,000, or 50,000 CFUs) was instilled under each flap; the eyes were examined for signs of infection and inflammation at 24 and 48 hours. In another five eyes, a lamellar flap was created in the same manner and the stromal bed was irrigated with 0.3% ofloxacin; the eyes were assessed for ocular inflammatory changes and evidence of crystalline deposits. Finally, in each of 15 additional eyes, 1,000 CFUs of S. aureus were instilled under a lamellar flap to create experimental infectious keratitis. The keratitis was treated according to three regimens: irrigation of the stromal bed with sterile balanced salt solution; irrigation of the stromal bed with 0.3% ofloxacin, followed by application of topical ofloxacin four times a day; application of topical ofloxacin only, four times a day. Eyes were examined for infection and ocular inflammatory changes at 24 and 48 hours.

RESULTS

Staphylococcus aureus keratitis can consistently be produced under the stromal flap by inoculation of relatively few organisms. Irrigation of the stromal bed with commercial-strength topical ofloxacin does not appear to be toxic to the stromal bed, with no evidence of crystalline precipitates of the antibiotic. In our model of infectious keratitis after lamellar keratectomy, both topical ofloxacin alone and the combination of topical ofloxacin and irrigation of the stromal bed with 0.3% ofloxacin were effective at preventing S. aureus keratitis. However, the combined treatment of antibiotic irrigation plus topical antibiotic was more effective at preventing inflammation than topical ofloxacin alone.

CONCLUSIONS

In this model of S. aureus keratitis after lamellar keratectomy, irrigation of the stromal bed with antibiotic plus topical antibiotic appears to be both safe and effective for preventing infection.

Delayed keratitis after laser in situ keratomileusis

We report 2 cases of delayed keratitis that occurred after uneventful laser in situ keratomileusis (LASIK). The first patient presented with a peripheral corneal infiltrate 3 months after a LASIK enhancement procedure. The infiltrate progressed despite treatment with topical combination tobramycin-dexamethasone. The flap was then lifted and the interface was irrigated with fortified antibiotics. The keratitis promptly resolved, and the patient recovered a best corrected visual acuity (BCVA) of 20/20. The second patient presented with decreased vision, inflammation, and a sublamellar infiltrate 1 month after primary LASIK. The flap was promptly lifted and irrigated with antibiotics. Cultures were positive for Staphylococcus epidermidis. One week later, the infiltrate had resolved and BCVA had returned to 20/20. Delayed bacterial keratitis has been described as a rare occurrence after incisional refractive surgery. To the best of our knowledge, it has not yet been reported after LASIK. It is important to consider infectious keratitis in the differential diagnosis of a patient who presents with corneal inflammation, even months after having LASIK.

Culture-negative ulcerative keratitis after laser in situ keratomileusis

A 40-year old man, highly myopic in both eyes, had laser in situ keratomileusis (LASIK) in the left eye in November 1996. Corneal melting and ulceration and fine striae-like interface infiltrates were noticed 1 day postoperatively. There was no response to intensive topical antibiotics in the form of hourly ofloxacin 3% (Tarivid), and satellite lesions developed on day 4. Corneal scrapings for gram stain and culture were done twice. No bacterial or fungal organisms were identified. Intensive topical fortified vancomycin (50 mg/mL) was added, and the lesions resolved gradually over the ensuing 2 weeks. Eighteen months after LASIK, refraction was -1.50 - 0.75 x 105 in the left eye, and uncorrected visual acuity was 20/70, correctable to 20/25 with spectacles.

Interface fluid associated with diffuse lamellar keratitis and epithelial ingrowth after laser in situ keratomileusis

We report a case in which diffuse interface keratitis began 1 week after bilateral uneventful laser in situ keratomileusis (LASIK). A layer of fluid in the interface with epithelial ingrowth was noted in the left eye 20 days postoperatively. The same complication occurred in the right eye 5 months after LASIK. Dry-eye syndrome and steroid-induced intraocular pressure elevation occurred in this patient with pre-existing ocular hypertension. A long course of interface inflammation was resistant to topical steroids. Surgical removal of the epithelial ingrowth and drainage of the fluid, combined with medical treatment, resulted in resolution of the inflammation. The cytopathologic examination of the fluid showed epithelial cells without signs of inflammation. The clinical features of this case represent a new complication of LASIK.