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.     

Acanthamoeba keratitis after photorefractive keratectomy

A 37-year-old women developed severe suppurative keratitis immediately after having photorefractive keratectomy in her left eye. The keratitis was unresponsive to intensive topical antibiotic agents and topical and systemic steroids. Although the differential diagnosis included nonmicrobial and fungal keratitis, the clinical course and confocal microscopy suggested, and subsequent histopathologic examination confirmed, a diagnosis of Acanthamoeba keratitis. The amebic contamination probably resulted from exposure of the deepithelialized cornea to contaminated freshwater in a northern Wisconsin marsh. This case emphasizes the importance of encouraging patients with epithelial defects and bandage soft contact lenses to avoid exposure to contaminated freshwater until reepithelialization is complete.     

Paraformaldehyde-induced keratitis after photorefractive keratectomy.

We examined three patients who developed keratitis after myopic photorefractive keratectomy. All patients were treated on the same day and in all three cases paraformaldehyde tablets were used for disinfection of the excimer laser iris cone. All patients developed an intense postoperative corneal inflammation that resulted in corneal opacities. In the first patient, the opacities were central and persisted for at least 4 1/2 months postoperatively. He became more myopic than before the operation. His best spectacle-corrected visual acuity worsened by four Snellen lines. In the other two patients, the corneal opacities were paracentral and of less density. Six months postoperatively, these opacities were barely seen. In these two patients the postoperative best spectacle-corrected visual acuity remained unchanged or improved one Snellen line compared to the preoperative level. In all three patients, astigmatism increased postoperatively. These observations suggest that paraformaldehyde tablets are not safe for the disinfection of the excimer laser iris cone.     

准分子激光屈光性角膜切削术治疗重度近视

目的 探讨准分子激光屈光性角膜切削术（ＰＲＫ）治疗重度近视的疗效。方法 使用Ｃｈｉｒｏｎ Ｖｉｓｉｏｎ的Ｋｅｒａｃｏｒ１１６准分子激光机,采用多光区切削方法治疗重度近视４９例８９眼,屈光度范围：－１０．００～－２５．００Ｄ。术后随访１ａ,并对结果进行分析。结果 ８９眼重度近视ＰＲＫ术后１ａ时,裸眼视力≥１．０者１２眼,占３．４９％,０．５～０。８者１７眼,占１９．１０％,≤０．４者６０眼,占７６７     

PRK后丝状角膜病变的临床观察

目的：研究准分子激光角膜切削术（photorefractive keratectomy,PRK)术后丝状角膜病变（filamentary keratitis)的发病原因,临床特征及其预后,方法：对493例（958眼）进行PRK并随访1年,结果;发现丝状角膜病变患者19例（22眼）,不同屈光度组及男女性别组间发病率有显著差异,病变呈一过性表现,对视力及hazen 无明显影响,结论：PRK术后丝关角膜病变为角膜上皮修复过程中的一过性失控状态,其发生原因可能与角膜上皮基底膜,前弹力层和基质层被激光切削,长时间闭眼和泪液分泌增加等因素有关。     

Bilateral methicillin-resistant Staphylococcus aureus keratitis after photorefractive keratectomy

A 52-year-old woman with a history of liver transplantation developed bilateral corneal infiltrates 1 week after uneventful photorefractive keratectomy (PRK). Cultures grew methicillin-resistant Staphylococcus aureus (MRSA), resistant to fluoroquinolone antibiotics. The infections responded to topical vancomycin and resolved bilaterally over 3 weeks. Three months postoperatively, the uncorrected visual acuity (UCVA) was 20/20 in the right eye and 20/25 in the left eye; the best spectacle-corrected visual acuity (BSCVA) was 20/20 in both eyes. During the course of treatment, the patient reported chronic intermittent prophylactic use of oral ciprofloxacin. While fluoroquinolones typically provide excellent postoperative coverage, Staphylococcus organisms have a growing antibiotic resistance to fluoroquinolones, and MRSA may become a more prevalent organism in corneal infections. Chronic subtherapeutic fluoroquinolone use can increase the mutational resistance of Staphylococcus to fluoroquinolone and methicillin. The patient's frequent hospital visits placed her at high risk for MRSA colonization. This case represents the fifth reported case of MRSA keratitis after PRK.     

Infectious keratitis after photorefractive keratectomy in a comanaged setting

A 48-year-old man had simultaneous bilateral photorefractive keratectomy (PRK). The surgeon who performed the PRK did not see the patient in follow-up, and there was confusion regarding the comanaging doctor. Therefore, the patient was not examined immediately postoperatively. Several days later, he was hospitalized for an unrelated, painful orthopedic problem and heavily sedated. Seven days after the PRK, an ophthalmologist was consulted for ocular irritation and discharge. Examination showed bilateral, purulent conjunctivitis and severe infectious keratitis in the left eye. The patient was treated with periocular and topical antibiotics. Corneal cultures yielded Staphylococcus aureus. The keratitis resolved slowly, leaving the patient with hand motion visual acuity. A corneal transplant and cataract extraction was performed 15 months later, resulting in a best corrected visual acuity of 20/400 because of glaucomatous optic nerve damage. Severe infectious keratitis may occur after PRK. Poor communication between the surgeon, comanaging doctor, and patient may result in treatment delay.     

True prophylactic gentamicin application in experimental Pseudomonas keratitis

In an experimental model of Pseudomonas keratitis, 50 rabbit eyes were treated with gentamicin sulfate (3 mg/mL) prophylactically on four different treatment regimens. One group (13 eyes) received one drop of gentamicin sulfate every hour to a total of four drops, the last drop 25 minutes before inoculation. A second group (13 eyes) was given one drop of gentamicin sulfate one hour before inoculation. A third group (12 eyes) received one drop of gentamicin sulfate per minute to a total of 4 drops, the last drop 25 minutes prior to inoculation. A fourth group (12 eyes) received one drop of antibiotic 25 minutes before inoculation. Twelve control eyes received saline solution. Subsequently, a superficial corneal scratch was inflicted and each eye received one drop (0.05 mL) of a solution containing Pseudomonas aeruginosa. The infection rate in all four experimental groups was low, whereas all control eyes became infected. These results demonstrate the effectiveness of prophylactic antibiotic application in the prevention of Pseudomonas keratitis prior to superficial ocular trauma.     

Ocular rigidity evaluation after photorefractive keratectomy: an experimental study

PURPOSE: To evaluate possible changes of the ocular rigidity coefficient in vivo after photorefractive keratectomy (PRK) in a series of rabbit eyes, using an invasive ocular rigidity measurement device. METHODS: Sixteen eyes of 8 rabbits were used in this study. One eye from each rabbit underwent PRK for -10.00 diopters (D) in a 5-mm optical zone (92 microm) while the fellow eye served as the control. Five weeks later, the rabbits were examined under general anesthesia. The pressure-volume relationship and the ocular rigidity coefficient were determined in all 16 eyes, by injecting 200 microL of saline solution (in increments of 4.5 microL) through the limbus into the anterior chamber, while the intraocular pressure (IOP) was continually monitored with a transducer, up to a maximum limit of 40 mmHg. Data within an IOP range of 10 to 40 mmHg were used to calculate the ocular rigidity coefficient. RESULTS: The preoperative central corneal thickness was comparable (P = .73, paired t test) in the pre-PRK eyes (mean: 347.5 +/- 17.11 microm) and control eyes (mean: 349.1 +/- 17.46 microm). No statistically significant difference was noted in measured ocular rigidity coefficient between eyes treated with PRK and control eyes (mean rigidity coefficient: 0.42 +/- 0.12 mmHg/microL [range: 0.23 to 0.56] and 0.47 +/- 0.12 mmHg/microL [range: 0.28 to 0.62], respectively, with 95% confidence interval of the difference, lower: -0.10 to upper: 0.015, P = .121). CONCLUSIONS: Photorefractive keratectomy did not significantly alter ocular rigidity measurements in this experimental model.     

Fungal keratitis after photorefractive keratectomy: delayed diagnosis and treatment in a co-managed setting

PURPOSE: To report a case of fungal keratitis following photorefractive keratectomy (PRK) in a co-managed setting. METHODS: A 35-year-old man with a preoperative refraction of -13.00 +3.75 x 18 degrees OD, and -12.50 +2.50 x 70 degrees OS underwent bilateral simultaneous PRK. On postoperative day 16, the patient presented with complaints of decreased vision and foreign body sensation. Examination by the co-managing optometrist revealed a visual acuity of 20/200, and a central corneal ulcer. Cultures were not taken and the patient was started on topical ofloxacin and prednisolone acetate 1% every hour. The patient was instructed to follow-up with another optometrist closer to the patient's home. Tobradex (tobramycin 0.3% combined with dexamethasone 0.1%) was added to the treatment regimen on postoperative day 23, but the ulcer continued to worsen. The patient was then referred to an ophthalmologist where corneal cultures were performed, but came back negative. RESULTS: Despite treatment with fortified antibiotics, the ulcer perforated, requiring penetrating keratoplasty. Bacterial and fungal cultures were negative. Pathology examination of the specimen revealed fungal hyphae. CONCLUSIONS: Although co-management of refractive patients may be a common practice, it is not without risks. In this case, delayed diagnosis and inappropriate treatment resulted in a poor final outcome.     

Relative efficacy of the topical use of amikacin, gentamicin and tobramycin in experimental Pseudomonas keratitis

In a quantitative model of experimental Pseudomonas aeruginosa keratitis in guinea pigs, topical solutions of amikacin, gentamicin and tobramycin were equally effective. Solutions of 20 mg/ml were more effective than solutions of 3 mg/ml.     

Infectious keratitis after transepithelial photorefractive keratectomy: A case report

Transepithelial photorefractive keratectomy (tPRK) promotes faster re-epithelialization which in turn can reduce the risk of infectious keratitis in the postoperative period. We present a case of a 22-year-old man with infectious keratitis in his left eye 8 days after an uneventful bilateral tPRK. A 2 mm × 5 mm anterior stromal area of corneal infiltration with a same sized overlying epithelial defect was noted at the time of presentation. His uncorrected distance visual acuity was 20/63 in his left eye. Corneal scrapings showed Bordetella bronchiseptica. The infection responded to intensive treatment with topical levofloxacin 0.5% eye drops. The final visual acuity was 20/20 in the left eye.     

Methicillin-resistant Staphylococcus aureus keratitis after excimer laser photorefractive keratectomy1

A 43-year-old woman in good health was admitted to the hospital 3 days after photorefractive keratectomy (PRK) in the left eye with postoperative bandage contact lens application. She had developed a severe keratitis with ulceration and hypopyon. Upon the patient's admission to the hospital, the contact lens was removed. Ofloxacin eyedrops were prescribed 4 times a day. In the hospital, the patient was successfully treated with immediate thermocautery application, followed by full-thickness keratoplasty the next day and intensive systemic and topical antibiotics. Cultures were positive for methicillin-resistant Staphylococcus aureus (MRSA). Severe MRSA keratitis is a rare cause of infection after PRK.     

Efficacy of topical caspofungin in experimental fusarium keratitis

PURPOSE: To evaluate the efficacy of caspofungin in an experimental rabbit model of Fusarium keratitis and to compare it with amphotericin B. METHODS: Eighteen New Zealand white rabbits were randomly divided into 2 treatment groups and 1 control group. One cornea of each rabbit was inoculated with Fusarium solani spores. The first group received topical amphotericin B 0.15%, the second group received topical caspofungin 1%, and the control group received topical balanced salt solution hourly for 2 days and then 4 times daily for 3 additional days. Treatment effects were evaluated by clinical assessment at days 3 and 5 and by fungal culture after 5 days of treatment. RESULTS: In the treatment groups, progression of keratitis was inhibited, and cultures were sterile at the end of the study. In the control group, keratitis progressed, and cultures were positive for F. solani. CONCLUSIONS: Topical caspofungin is effective in Fusarium keratitis, and clinical efficacy studies seem justified.     

Effects of topical tranilast on corneal haze after photorefractive keratectomy

PURPOSE: To determine whether topical tranilast might reduce corneal haze through suppression of transforming growth factor (TGF)-beta1 synthesis in keratocyte after photorefractive keratectomy. SETTING: Department of Ophthalmology, Korea University College of Medicine, Seoul, Republic of Korea. METHODS: Photorefractive keratectomy was performed on 48 eyes of 28 white rabbits and 24 eyes in a tranilast group were treated with tranilast solution, and the other 24 eyes in control group were treated with saline after laser ablation. The grades of corneal haze at 1, 2, 4, and 8 weeks after surgery were evaluated in 10 eyes of each group for comparison. Immunohistochemistry was performed on 10 eyes of each group, and Western blot analysis was done on 4 eyes of each group for studying TGF-beta1 expression at postoperative day 7. RESULTS: There was no statistically significant difference in corneal haze between 2 groups from week 1 to week 4 after surgery, but a significant difference was found at week 8 after photorefractive keratectomy (P=.02). The mean number of keratocytes that expressed TGF-beta1 in the tranilast group was 58.3 (+/-17.2), which showed significant difference, compared with that of the control group, 104.5 (+/-23.0) (P<.01). Western blot analysis also revealed that the amount of TGF-beta1 in tranilast group was slightly less than the control group. CONCLUSIONS: Topical tranilast could reduce corneal haze by suppressing TGF-beta1 expression in keratocytes after photorefractive keratectomy.