Diffuse lamellar keratitis: isolation of endotoxin and demonstration of the inflammatory potential in a rabbit laser in situ keratomileusis model

Chryseobacterium indologenes Keratitis: Successful Treatment of Multidrug-Resistant Strain

A 72-year-old male with history of monocular vision with complete vision loss in his right eye from previous retinal detachment presented with 20/200 vision in the left eye with a corneal ulcer. Culture was obtained, and the patient was started on fortified tobramycin, fortified vancomycin, and amphotericin. Despite the antibiotics, the patient did not significantly improve, after which another culture was obtained before the patient was taken to the surgery for cryotherapy and a partial conjunctival flap. The culture identified Chryseobacterium indologenes. There have been fewer than a handful of cases reported in the last three decades with different antibiotic susceptibility profiles. Our patient was successfully treated with ciprofloxacin and ceftazidime with the final vision of 20/40.

Pathophysiology and Treatment of Diffuse Lamellar Keratitis

PURPOSE

To review cytokine- and chemokine-mediated mechanisms of diffuse lamellar keratitis (DLK) after lamellar corneal surgical procedures.

METHODS

Review of the basic science and clinical literature.

RESULTS

DLK can occur early or late (months to decades) after all lamellar corneal surgeries, including laser in situ keratomileusis, small incision lenticule extraction, anterior lamellar keratoplasty, and Descemet's stripping automated endothelial keratoplasty. It is most commonly triggered by epithelial injury during or after lamellar surgery, which leads to the release of interleukin (IL)-1α, IL-1β, and tumor necrosis factor (TNF)-α from the epithelium and into the stroma. These chemokines directly attract inflammatory cells into the cornea from the limbal blood vessels and also bind to receptors on keratocytes and corneal fibroblasts where myriad chemokines are upregulated that also chemotactically attract monocytes, macrophages, granulocytes, lymphocytes, and other bone marrow-derived cells into the corneal stroma. Other factors that can trigger DLK include retained blood in the interface, endotoxins and other toxins, and excessive keratocyte necrosis caused by femtosecond lasers. Infiltrating cells show a preference to enter any lamellar interface in the cornea, regardless of the time since surgery, because of the ease of movement toward the chemotactic attractants relative to the surrounding stroma with intact collagen lamellae and stromal cells that serve as relative barriers impeding motility. The mainstay of treatment is topical corticosteroids, but severe cases may also be treated with flap lift irrigation and systemic corticosteroids.

CONCLUSIONS

DLK can occur early or late after any lamellar corneal surgical procedure and is most commonly triggered by epithelial-stromal-bone marrow-derived cellular interactions mediated by corneal cytokines and chemokines. [J Refract Surg. 2020;36(2):124-130.].

LASIK interface complications: etiology, management, and outcomes

PURPOSE

To describe the etiology, diagnosis, clinical course, and management of LASIK interface complications.

METHODS

Literature review.

RESULTS

Primary interface complications include infectious keratitis, diffuse lamellar keratitis, central toxic keratopathy, pressure-induced stromal keratopathy (PISK), and epithelial ingrowth. Infectious keratitis is most commonly caused by Methicillin-resistant Staphylococcus aureus (early onset) or atypical Mycobacterium (late onset) postoperatively, and immediate treatment includes flap lift and irrigation, cultures, and initiation of broad-spectrum topical antibiotics, with possible flap amputation for recalcitrant cases. Diffuse lamellar keratitis is a white blood cell infiltrate that appears within the first 5 days postoperatively and is acutely responsive to aggressive topical and oral steroid use in the early stages, but may require flap lift and irrigation to prevent flap necrosis if inflammation worsens. In contrast, PISK is caused by acute steroid response and resolves only with cessation of steroid use and intraocular pressure lowering. Without appropriate therapy PISK can result in severe optic nerve damage. Central toxic keratopathy mimics stage 4 diffuse lamellar keratitis, but occurs early in the postoperative period and is noninflammatory. Observation is the only effective treatment, and flap lift is usually not warranted. Epithelial ingrowth is easily distinguishable from other interface complications and may be self-limited or require flap lift to treat irregular astigmatism and prevent flap melt.

CONCLUSIONS

Differentiating between interface entities is critical to rapid appropriate diagnosis, treatment, and ultimate visual outcome. Although initial presentations may overlap significantly, the conditions can be readily distinguished with close follow-up, and most complications can resolve without significant visual sequelae when treated appropriately.

Treatment of multidrug-resistant Flavobacterium indologenes keratitis with trimethoprim-sulfamethoxazole

PURPOSE

To describe the history, clinical presentation, and successful medical management of a case of multidrug-resistant Flavobacterium indologenes keratitis.

METHODS

An 83-year-old pseudophakic female presented with a 2-day history of decreased visual acuity, light sensitivity and dull ocular pain in her right eye. Two weeks before presentation, the patient had been treated for a red eye with combination topical loteprednol etabonate (0.5%) and tobramycin (0.3%) eye drops. Corneal scrappings were performed by the referring ophthalmologist, and hourly administration of gatifloxacin 0.3% eye drops was started. Evaluation consisted of slit lamp examination, organism identification, and antibiotic sensitivity testing.

RESULTS

Examination of the right eye revealed a central 5-mm X 2-mm anterior stromal infiltrate with an overlying epithelial defect. Gatifloxacin 0.3% eye drops were stopped, and hourly topical fortified vancomycin (50 mg/mL) and ceftazidime (50 mg/mL) eye drops were instituted. Oxidase-positive gram-negative bacilli were identified in the thioglycollate broth on day 3, and therefore, vancomycin was discontinued and hourly ciprofloxacin 0.3% eye drops were added to the regimen. The cultures ultimately grew F. indologenes, which was highly resistant to all antibiotics tested except for trimethoprim-sulfamethoxazole. Accordingly, ciprofloxacin 0.3% and ceftazidime were discontinued. The patient was started on hourly topical trimethoprim (16 mg/mL)/sulfamethoxazole (80 mg/mL) eye drops, resulting in clinical control of the infection over a period of 1 month.

CONCLUSIONS

Flavobacterium indologenes keratitis can be resistant to treatment with many medications, and antibiotic susceptibility profile testing in these cases may provide crucial information to help eradicate the infection.

Incidence of diffuse lamellar keratitis after laser in situ keratomileusis associated with the IntraLase 15 kHz femtosecond laser and Moria M2 microkeratome

PURPOSE

To analyze the incidence of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) performed with an IntraLase 15 kHz femtosecond laser (IntraLase, Corp.) or a Moria M2 mechanical microkeratome (Moria SA).

SETTING

Vissum Madrid, Madrid, Spain.

METHODS

This retrospective study compared the incidence of DLK in consecutive LASIK procedures performed with the IntraLase 15 kHz femtosecond laser (study group) or the Moria M2 microkeratome (control group). Two surgeons performed both types of surgeries (femtosecond laser and microkeratome) using the same excimer laser (Technolas 217, Bausch & Lomb). During the first week postoperatively, topical dexamethasone drops were applied 8 times daily in the femtosecond group and 4 times daily in the mechanical microkeratome group.

RESULTS

A total of 2000 consecutive eyes were analyzed (1000 eyes in each group). Diffuse lamellar keratitis stage 2 developed in 1 patient in each group; DLK stage 3 developed in 4 patients in the study group and in no patient in the control group (P = .03).

CONCLUSION

Despite more intense postoperative steroid treatment, DLK seemed to occur more frequently after LASIK performed with the IntraLase 15 kHz femtosecond laser than after LASIK performed with the Moria M2 microkeratome.

Corneal interface contamination during laser in situ keratomileusis

PURPOSE

To measure the rate of corneal interface contamination during laser in situ keratomileusis (LASIK), determine probable sources of the contamination, and evaluate how the cornea reacts to the contamination.

SETTING

Department of Ophthalmology, Baqyatallah Hospital, Baqyatallah University, Tehran, Iran.

METHODS

In this case series, 200 eyes were evaluated for the corneal interface contamination at the end of LASIK. Cultures were taken from the upper and lower eyelid margins and the inferior fornices before surgery and from the corneal interface and the instrument at the end of surgery. Media were cultured at 37 degrees C for 14 days under aerobic and anaerobic conditions. Bacteria from positive cultures were isolated and identified by biochemical procedures to determine the species of the organisms.

RESULTS

The rate of contamination was 24.5%. The most common retrieved organism was Staphylococcus epidermidis (43 cases, 87.7%). None of the contaminated or noncontaminated cases developed corneal ulcers; however, 2 eyes developed diffuse lamellar keratitis.

CONCLUSION

The corneal stroma has the ability to clear introduced microorganisms during LASIK.

Description, Etiology, and Prevention of an Outbreak of Diffuse Lamellar Keratitis After LASIK

PURPOSE

To describe an outbreak of diffuse lamellar keratitis (DLK) and provide a hypothesis about the etiology.

METHODS

A retrospective analysis was carried out on 328 eyes of 220 patients who underwent LASIK over 9 months. The occurrence of DLK using two different methods of cleaning and sterilizing surgical instruments and an autoclave reservoir were analyzed. Microbial analyses were carried out by two laboratories on samples obtained from the original autoclave reservoir and tubing. A chi-square test was used to compare qualitative values. The Student t test was used to compare numerical values.

RESULTS

Forty-six (24.5%) of 188 cases of DLK were diagnosed. Sphingomona paucimobilis and Burkholderia pickettii were isolated in the reservoir of the steam sterilizer. Electron microscopy revealed gram-negative microbes on the tubing walls. After changing the reservoir of the steam sterilizer and implementing a new cleaning and sterilization protocol based on air-drying the instruments and draining and drying the reservoir of the sterilizer, the occurrence of DLK stopped. No statistically significant correlation was noted between the occurrence of DLK and gender, age, or volume of tissue removed.

CONCLUSIONS

Data obtained during this DLK outbreak support the theory that a bacterial endotoxin, which can survive short-cycle steam sterilization, could be responsible for an outbreak of DLK. We recommend cleaning and sterilization protocols based on air-drying surgical instruments and leaving the reservoirs completely dry at the end of each surgical day.

Central Flap Necrosis After LASIK With Microkeratome and Femtosecond Laser Created Flaps

PURPOSE

To report nine cases of severe central flap inflammation and necrosis after LASIK.

METHODS

A retrospective chart review was conducted on 17,100 LASIK cases performed at two laser centers in Indiana from January 1995 through May 2005. All patients with central lamellar flap necrosis were identified.

RESULTS

Severe central flap inflammation and necrosis occurred in nine eyes of eight patients. Six patients underwent flap creation with a mechanical microkeratome and two with a femtosecond laser. Of eight eyes with > 2-month follow-up, one lost at least two lines of best spectacle-corrected visual acuity and two experienced a hyperopic shift in spherical equivalent refraction. Typically, inflammation was minimal the day after surgery, peaked 5 to 10 days later, and subsided by 60 days. Six of nine cases were treated by lifting the flap and irrigating the stromal bed. In each of these cases, few or no inflammatory cells were observed in the stromal bed, the posterior flap surface was intact, and the central portion of the anterior flap had a jelly-like consistency.

CONCLUSIONS

Central lamellar flap necrosis appears to differ from diffuse lamellar keratitis because the location of stromal inflammation is not in the flap interface but rather in the flap anterior stroma. Treatment with corticosteroids seemed to have little effect on outcomes. This is thought to be the first documentation of central lamellar flap necrosis following the use of a femtosecond laser.

Confocal Microscopy and Histopathological Examination of Diffuse Lamellar Keratitis in an Experimental Animal Model

PURPOSE

To investigate the cell populations and structural alterations of the cornea in an experimental model of diffuse lamellar keratitis (DLK) using confocal microscopy and histopathology.

METHODS

A corneal flap was cut in 22 eyes of 11 New Zealand rabbits and the stromal interface was exposed to balanced salt solution (BSS, BSS group) and Pseudomonas aeruginosa lipopolysaccharide (LPS) endotoxin (5 mg/mL) (LPS 5 mg/mL group) and (3.5 mg/mL) (LPS 3.5 mg/mL group). Postoperatively, eyes were examined with a slit-lamp microscope (DLK grading) and confocal microscopy. Animals were sacrificed on day 3 (BSS group and LPS 5 mg/mL group) and day 4 (LPS 3.5 mg/mL group). Corneoscleral buttons were excised and processed for histopathologic examination.

RESULTS

Seven eyes were excluded. Slit-lamp microscopy revealed no cellular infiltration in the BSS group (five eyes). In the LPS groups, all eyes developed DLK, with iritis only observed in grade III eyes. In the LPS 5 mg/mL group, four eyes had DLK grade III, with iritis in three eyes. In the LPS 3.5 mg/mL group, three eyes had grade II and three eyes had grade III with iritis. On confocal microscopy, the BSS group had no cellular infiltration. Dense accumulation of inflammatory cells at the interface was noted in both LPS groups. Histopathology in the BSS group had a normal appearance. In the LPS groups, an inflammatory infiltrate was present at the interface that consisted of three cell populations--eosinophils, neutrophils, and lymphocytes.

CONCLUSIONS

Lipopolysaccharide endotoxin induced DLK in all exposed eyes, with iritis in a considerable proportion of eyes. The infiltrate consisted of three cell populations. Confocal microscopy showed the infiltrate in all affected eyes. Histopathological and confocal microscopic findings correlated well with the clinical appearance.

Surgical-glove-related diffuse lamellar keratitis after laser in situ keratomileusis: long-term outcomes

PURPOSE

To study the long-term refractive results in eyes that developed surgical-glove-related diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK).

SETTING

Department of Ophthalmology, Hospital Provincial, Toledo, Spain.

METHODS

This retrospective review analyzed an epidemic of surgical-glove-related DLK over a 5-month period at a single hospital. Twenty-four eyes (24 patients) that developed DLK (DLK group) were compared to 30 eyes (30 consecutive patients) that had surgery during the same time but had an uneventful postoperative course (control group). Follow-up was 12 months in all cases.

RESULTS

Twelve months after LASIK, the mean spherical equivalent was 0.14 diopter (D) +/- 0.36 (SD) in the DLK group and -0.07 +/- 0.33 D in the control group (P=.03). The mean uncorrected visual acuity was 0.91 +/- 0.18 and 0.90 +/- 0.17, respectively (P = .81). The mean best spectacle-corrected visual acuity (BSCVA) was 0.97 +/- 0.08 in the DLK group and 0.99 +/- 0.06 in the control group (P = .42). At 1 year, 91.7% of eyes in the DLK group and 93.3% of eyes in the control group were within +/-0.50 D of the attempted correction (P = .82). The BSCVA was 1.0 or better in 87.5% and 93.3%, respectively (P =.46).

CONCLUSIONS

Early diagnosis and appropriate treatment of glove-related DLK provided visual outcomes that were similar to those in eyes with an uneventful postoperative course. These good results are consistent with those in studies of classic DLK.

Diffuse lamellar keratitis induced by toxic chemicals after laser in situ keratomileusis

PURPOSE

To assess whether toxic chemicals produced during autoclaving sterilization were 1 of the main causes of diffuse lamellar keratitis (DLK) and to analyze the clinical outcomes of patients developing DLK after laser in situ keratomileusis (LASIK) treated with intensive topical corticosteroids.

SETTING

Department of Ophthalmology, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China.

METHODS

A total of 14 eyes of 7 patients received technically smooth LASIK and developed DLK, including 6 severe and 8 mild DLK cases. In all eyes the same microkeratome was used; it was contaminated with toxic chemical materials produced accidentally by coautoclaving instruments and a foam piece.

RESULTS

Six eyes of 3 patients developed severe DLK on the same day, and 8 eyes of 4 patients developed mild DLK during the next LASIK surgery. After intensive topical corticosteroid treatment, lamellar infiltrates disappeared in 3 days in mild DLK eyes and 2 weeks in severe DLK eyes. No eye was treated with flap lifting and interface irrigation. For grade 4 DLK, the corneal opacity and flap folds disappeared in 4 weeks. There were no instances of permanent corneal scarring or loss of best spectacle-corrected visual acuity.

CONCLUSIONS

Toxic chemicals produced during instrument autoclaving sterilization are a possible cause of DLK. Immediate diagnosis and treatment with intensive corticosteroid drops are critical and can resolve severe DLK.

Role of topical fluoroquinolones on the pathogenesis of diffuse lamellar keratitis in experimental in vivo studies

PURPOSE

To investigate the potential role of commercially available topical fluoroquinolones in diffuse lamellar keratitis (DLK) using New Zealand White rabbit models.

SETTING

Campbell Ophthalmic Microbiology Laboratory at the University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

METHODS

In a DLK challenge model, laser in situ keratomileusis flaps were created by a microkeratome in rabbit eyes (n = 10 per group) and the stromal beds were treated with 1 drop of Ciloxan (ciprofloxacin 0.3%), Ocuflox (ofloxacin 0.3%), balanced salt solution (BSS), or Pseudomonas aeruginosa endotoxin before flap closure. After the procedure, eyes were treated with the same drugs 4 times daily. On postoperative day 1, the eyes were examined by slitlamp and graded (modified Linebarger DLK grading scale) in a masked fashion. In a DLK exacerbation model, all eyes received 1 drop of endotoxin on the stromal interface followed by flap closure. After the procedure, the rabbit eyes (10 per group) were treated 4 times daily with Ciloxan, Ocuflox, or BSS and graded for DLK on postoperative day 1 as before.

RESULTS

In the challenge model, Ciloxan, Ocuflox, and endotoxin all produced higher median DLK scores than the BSS control (P = .02). Ciloxan produced significant DLK in more eyes and had higher median scores (70%, 1.0) than Ocuflox (40%, 0.5) or endotoxin (45%, 0.5) (P = .05). In the endotoxin-induced model, Ciloxan produced significantly higher DLK scores than Ocuflox or BSS (P = .05).

CONCLUSIONS

Topical fluoroquinolones caused and exacerbated DLK in rabbit models. Ocuflox was associated with less DLK than Ciloxan. The clinical significance of these findings can only be assessed in clinical trials.

Diffuse lamellar keratitis complicating laser in situ keratomileusis

PURPOSE

To describe a surveillance system and summarize data between January 2000 and December 2002 regarding diffuse lamellar keratitis (DLK), a complication of laser in situ keratomileusis (LASIK) surgery.

SETTING

Community-based clinics in British Columbia, Canada, in which LASIK surgery is performed.

METHODS

Monthly, all clinics in which LASIK is performed reported the number of LASIK procedures and nonnominal cases of DLK (by grade and onset date) to the British Columbia Centre for Disease Control. Diffuse lamellar keratitis outbreaks were investigated, and prevention and control measures were recommended.

RESULTS

From 2000 to 2002, approximately 72,000 LASIK procedures were performed, with a mean DLK incidence rate of 0.67% (95% confidence interval, 0.61-0.73). The overall proportion of DLK cases attributed to outbreaks was 64%, decreasing from 72% in 2000 to 40% in 2003.

CONCLUSIONS

An effective DLK surveillance program was implemented at all laser refractive clinics in British Columbia. Reported DLK incidence was 0.67 cases per 100 procedures, with 64% occurring in outbreaks.

Surgical glove-associated diffuse lamellar keratitis

PURPOSE

To demonstrate a potential cause of a prolonged epidemic of diffuse lamellar keratitis (DLK).

METHOD

This retrospective review analyzed an epidemic of diffuse lamellar keratitis over a 3-year period in a single surgery center. Altering the brand of surgical gloves used during surgery was associated with an elimination of the DLK epidemic. Optical microscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and Fourier transform infrared (FTIR) spectroscopy were performed on both brands of surgical gloves to allow for comparisons and determine possible surface contaminants responsible for the DLK outbreaks.

RESULTS

The incidence of DLK during the epidemic ranged from 2% to 38% on a quarterly basis for the 3-year period. A change in the brand of surgical gloves resulted in a cessation of DLK. Surface analysis of both brands of gloves revealed extensive silicone oil contamination on the internal and external surfaces of the DLK-associated gloves and insignificant amounts of silicone oil on the external surface of the DLK-free gloves.

CONCLUSION

Silicone oil contamination of surgical gloves appears to be associated with epidemic DLK.

Observation of the corneal flap interface with metal particles in a rabbit model

PURPOSE

To observe changes, such as diffuse lamellar keratitis, at the corneal interface when metal particles from microkeratome blades were left in rabbit eyes.

SETTING

Department of Ophthalmology, Tokyo Dental College, Suidobashi Hospital, Tokyo, Japan.

METHODS

Following the creation of a corneal flap with microkeratome, metal particles from a microkeratome blade were placed at the corneal interface in 14 rabbit eyes. Microscopic and histopathologic changes were compared with those in the control eyes (n = 4), which did not receive any metal particles. Each examination was conducted at 3 days, 2 weeks, and 1 and 3 months postoperatively. The change in the depth of the metal particles was also measured.

RESULTS

Slitlamp examination did not show an inflammatory reaction or corneal opacification in any eye (100%) with metal particles at the flap interfaces. Histopathologic examinations showed no obvious changes at the flap interfaces or around the metal particles in any eye.

CONCLUSION

Inflammatory reactions, such as diffuse lamellar keratitis, do not appear to be induced by metal particles from the microkeratome blade itself.

Use of Polymyxin as an Endotoxin Blocker in the Prevention of Diffuse Lamellar Keratitis in an Animal Model

PURPOSE

To determine whether bacterial endotoxin, lipopolysaccharide (LPS), could induce diffuse lamellar keratitis (DLK) in an animal model and whether DLK could be prevented by endotoxin blockers such as polymyxin.

METHODS

Laser in situ keratomileusis (LASIK) flaps were created in rabbit eyes. The stromal bed was treated with 20 microg of Burkholderia cepacia LPS or balanced salt solution (BSS). Development of DLK, histological degree of inflammation, and presence of LPS detected by anti-LPS antibody were evaluated after 48 hours. In a second experiment, all eyes received LPS and were randomly assigned to receive either polymyxin in the form of two drops of Polytrim (Allergan, Irvine, Calif) on the stromal bed or two drops of BSS.

RESULTS

In the animal model study, LPS was significantly associated with the development of DLK (P<.05, n=30). Infiltration with polymorphonuclear cells and presence of DLK were found in LPS treated eyes but not in controls. In the second experiment, 4 (27%) of 15 eyes that received polymyxin in addition to LPS developed DLK compared to 18 (95%) of 19 eyes that received only LPS (P<.05, n=34). There was a trend towards higher flap displacement in polymyxin treated eyes but this was not significant (P=.07).

CONCLUSIONS

Diffuse lamellar keratitis in a rabbit model can be caused by bacterial endotoxin (LPS). Endotoxin blockers, such as polymyxin, are effective in decreasing the incidence of endotoxin-induced DLK in a rabbit model.

The epidemiology of diffuse lamellar keratitis

PURPOSE

To report the incidence and outcomes of diffuse lamellar keratitis (DLK) after LASIK and to analyze potential causative factors.

METHODS

Retrospective review of 15,119 cases (11,232 primary procedures and 3887 enhancements) from 7168 patients undergoing LASIK from May 1995 through October 2002, comparing preoperative data and postoperative outcomes for each case developing DLK to patients in the study population and a control series of eyes that did not develop DLK.

RESULTS

We identified 61 eyes (0.40%) that developed DLK after LASIK. Three study groups were identified based on sterilization protocols used: (1) steam autoclave without reservoir (8348 cases), (2) cassette autoclave with reservoir (6771 cases), (3) steam autoclave without reservoir and new instrument cleaner (1758 cases). Significantly more eyes developed DLK with Protocol 2 (47 cases, 0.94%) than with Protocol 1 (11 cases; 0.1%; P < 0.0001) or Protocol 3 (3 cases, 0.2%; P < 0.0005). There was no significant difference in the incidence of DLK in Protocol 1 versus Protocol 3. DLK was significantly more common after primary procedures than with enhancement procedures only under Protocol 2. No individual developed DLK after more than 1 procedure. Treatment protocols included frequent topical steroids only (24 cases, 39.3%), frequent topical steroids and oral steroids (19 cases, 31.2%), or topical and oral steroids combined with lifting and irrigating beneath the flap (18 cases, 29.5%). Final refractions and visual acuities were not significantly different in eyes that developed DLK and those that did not.

CONCLUSIONS

DLK is a nonspecific inflammatory response to multiple stimuli that cannot be attributed solely to individual variation in the inflammatory response, the microkeratome, or material deposited by the microkeratome. Sterilizers with reservoirs may cause some cases of DLK. With appropriate diagnosis and treatment, DLK should resolve without sequelae, yielding visual outcomes comparable to cases with uneventful postoperative courses.

RISKS OF INTRAVITREOUS INJECTION: A COMPREHENSIVE REVIEW

PURPOSE

To evaluate the prevalence of the most common serious adverse events associated with intravitreous (IVT) injection.

METHODS

A systematic search of the literature via PubMed from 1966 to March 1, 2004, was conducted to identify studies evaluating the safety of IVT injection. Data submitted in New Drug Applications to the U.S. Food and Drug Administration for drugs administered into the vitreous were included where available. Serious adverse events reported in each study were recorded, and risk per eye and risk per injection were calculated for the following serious adverse events: endophthalmitis, retinal detachment, iritis/uveitis, intraocular hemorrhage, ocular hypertension, cataract, and hypotony. Rare complications also were noted.

RESULTS

Data from 14,866 IVT injections in 4,382 eyes were analyzed. There were 38 cases of endophthalmitis (including those reported as pseudoendophthalmitis) for a prevalence of 0.3% per injection and 0.9% per eye. Excluding cases reported specifically as pseudoendophthalmitis, the prevalence of endophthalmitis was 0.2% per injection and 0.5% per eye. Retinal detachment, iritis/uveitis, ocular hypertension, cataract, intraocular hemorrhage, and hypotony were generally associated with IVT injection of specific compounds and were infrequently attributed by the investigators to the injection procedure itself. Retinal vascular occlusions were described rarely in patients after IVT injection, and it was unclear in most cases whether these represented true injection-related complications or chance associations.

CONCLUSION

The risk of serious adverse events reported after IVT injection is low. Nevertheless, careful attention to injection technique and appropriate postinjection monitoring are essential because uncommon injection-related complications may be associated with permanent vision loss.

Detection of neutrophils in late-onset interface inflammation associated with flap injury after laser in situ keratomileusis

OBJECTIVE

To report a case with late-onset interface inflammation associated with traumatic flap injury at 7 months after laser in situ keratomileusis (LASIK) and to describe the type of infiltrating cells in the tears of the patient.

METHODS

Interventional case report. A 24-year-old male patient who underwent uneventful LASIK on both eyes received blunt trauma from the tip of a shoe in the left eye 7 months after surgery. The corneal flap of his left eye was lacerated across the pupillary area. Inflammatory cells were observed under the lacerated flap segment. Tear fluid was collected from his left eye 3 days after the injury and assessed by tear cytology. For controls, tears of 2 patients who underwent LASIK and developed no interface inflammation were collected the next day after their surgeries and examined.

RESULTS

Tear fluid of the patient with interface inflammation contained numerous neutrophils. Tears of control patients contained only a few epithelial cells and cell debris but no inflammatory cells. The inflammation was decreased by systemic and topical steroids. However, irregular astigmatism caused by stromal scarring remained, resulting in decreased best-corrected visual acuity.

CONCLUSIONS

Interface inflammation can be caused by late-onset flap injury. Neutrophils detected in the tears may reflect a major component of cells infiltrating the interface after LASIK.

Pressure-Induced Interface Keratitis: A Late Complication Following LASIK

PURPOSE

Interface inflammation is a common complication of laser in situ keratomileusis (LASIK). The most well-described presentation is diffuse lamellar keratitis (DLK), which typically develops early after LASIK and responds quickly to topical steroids. In this report, we describe a novel presentation of interface inflammation that resembles DLK in appearance but presents late in the postoperative period, is associated with increased intraocular pressure, and is exacerbated by steroid treatment.

METHODS

A retrospective case series and chart review of all patients treated in our tertiary care private practice for late-onset interface inflammation associated with elevated intraocular pressure.

RESULTS

Ten eyes in 6 patients with late-onset interface inflammation and increased intraocular pressure were identified. At presentation, all patients were presumed to have classic DLK and were treated initially with aggressive topical steroids. Eight of the 10 eyes were receiving topical steroids at the time of presentation. The average time of presentation was 17 days after LASIK (range, 7-34). Elevated intraocular pressure was noted on average 28 days after presentation (range, 8-69). Lamellar inflammation was exacerbated by topical steroids. Resolution of the interface inflammation did not occur until intraocular pressure was controlled.

CONCLUSIONS

This case series describes a clinically distinct form of interface inflammation that presents late and is associated with elevated intraocular pressure. The lamellar inflammation was refractory to topical steroids and only resolved when pressure was controlled. These findings suggest that elevated intraocular pressure can contribute to interface inflammation. Postoperative assessment of intraocular pressure is essential in patients presenting with flap inflammation.

Evaluation of preoperative and postoperative prophylactic regimens for prevention and treatment of diffuse lamellar keratitis

PURPOSE

To investigate preoperative and postoperative prophylactic treatment with different pharmacological agents before flap cutting and exposure to a diffuse lamellar keratitis (DLK) causative agent.

SETTING

Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

The study comprised 48 eyes of 24 Dutch-belted rabbits. Three days before a corneal flap was cut and the corneal interface was exposed to Pseudomonas aeruginosa lipopolysaccharide endotoxin, a DLK causative agent, the eyes were randomly assigned to treatment with a mast-cell stabilizer, a nonsteroidal antiinflammatory drug (NSAID), or a corticosteroid or left without treatment as controls. The treatment was maintained throughout the 1-week follow-up. Slitlamp examinations and photographs were performed at 1, 3, 5, and 7 days; DLK was graded by a masked observer from 0 (no DLK) to IV. Corneal interface scrapings were performed in selected eyes on day 7.

RESULTS

At the end of the follow-up, 36 eyes were available for evaluation. At 1 week, 100% of the control eyes and the eyes treated with the mast-cell stabilizer developed DLK; in the NSAID-treated and corticosteroid-treated eyes, the DLK rate was 86% and 70%, respectively. At 1 day, the severity of DLK was significantly lower in eyes treated with the mast-cell stabilizer (0.44) and at 7 days, it was significantly lower in corticosteroid-treated eyes (0.3) than in the control group (1.5 and 1.4, respectively) (P<.05, Wilcoxon test). Corneal interface scraping from an eye with grade III DLK showed numerous inflammatory cells.

CONCLUSIONS

Preoperative and postoperative treatment with corticosteroids significantly reduced the severity of DLK compared to the untreated control eyes in this animal model. Treatment with a mast-cell stabilizer and an NSAID had less effect on the postoperative course of DLK.

Risk Factors for Development of Diffuse Lamellar Keratitis After Laser in situ Keratomileusis

PURPOSE

To investigate the risk factors and mechanisms of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK).

METHODS

In 5708 eyes of 2927 patients who underwent LASIK, the patient's background, clinical findings, and surgical data were retrospectively evaluated and compared with patients who had DLK and those who did not (non-DLK group).

RESULTS

DLK occurred in 46 of 5708 eyes (0.81%). DLK occurred more frequently in eyes operated with the MK-2000 microkeratome (1.1%) than with the LSK-One microkeratome (0.6%; P = .039). Corneal endothelial cell density (2686.8 +/- 235.3/mm2) was significantly lower in eyes that developed DLK than in eyes without DLK (2783.8 +/- 275.5/mm2; P = .017). The width of palpebral fissure in a normal state and the maximum opening position were significantly larger in the DLK group (10.3 +/- 1.9 mm and 18.1 +/- 7.2 mm, respectively) than the non-DLK group (8.3 +/- 1.6 mm with P < .001; 11.5 +/- 2.0 mm with P = .012).

CONCLUSIONS

The type of microkeratome, lower corneal endothelial cell density, and larger palpebral fissure were potential risk factors for DLK after LASIK. These factors may be associated with delayed wound healing of the corneal flap margin, resulting in poor sealing of the flap, which may induce the influx of inflammatory cells.

Residual cleaner after normal cleaning of laser in situ keratomileusis instruments

PURPOSE

To determine whether residual cleaner could be detected in the rinse solution of surgical instruments after a standard cleaning protocol.

SETTING

Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

The wavelength for maximum absorbance of 5 cleaners (Endozime) [The Ruhof Corp.], Enzol/Cidezyme [Advanced Sterilization Products], and Klenzyme [Steris Co.] enzymatic detergents; Palmolive Ultra dishwashing liquid [Colgate-Palmolive Co.]; and Universal concentrated surgical instrument cleaner and lubricant [B. Graczyk, Inc.]) was determined. Identically designed stainless-steel and titanium instruments were cleaned using a standardized protocol. Water temperatures of 25 degrees C (room temperature) or 40 degrees C (warm temperature) were used to rinse the instruments. The amount of residual cleaner in each rinse solution and remaining on each instrument at the completion of the cleaning procedure as a percentage of the total cleaner was determined.

RESULTS

Residues of all cleaners were detected using a standard protocol involving rinse solutions at 25 degrees C. Increasing the temperature of the rinse solutions significantly reduced the cleaner residues (P<.05, Friedman repeated-measures analysis of variance on ranks test and Student-Newman-Keuls test) regardless of the instrument material. No significant difference was detected in the residual cleaners on stainless-steel and titanium instruments.

CONCLUSIONS

Lower levels of cleaner residue were found on surgical instruments after a standard cleaning protocol using warm rinse water. Because cleaner residue has been reported to cause inflammation (eg, diffuse lamellar keratitis) after laser in situ keratomileusis (LASIK), it is advisable to use cleaners and cleaning protocols that result in acceptable cleaning without detectable levels of cleaner residue to avoid potentially harmful effects to the cornea after LASIK.

Detection of neutrophils and possible involvement of interleukin-8 in diffuse lamellar keratitis after laser in situ keratomileusis

PURPOSE

To investigate the cell populations in diffuse lamellar keratitis (DLK) infiltration after laser in situ keratomileusis and the possible mechanism underlying the infiltration.

SETTING

Department of Ophthalmology, Tokyo Dental College, Chiba, Japan.

METHODS

To develop DLK in rabbit eyes, 25 microL of lipopolysaccharide (LPS) solution at a concentration of 50 microg/mL was applied to the stromal bed beneath corneal flaps. For control rabbits, phosphate-buffered saline was applied. Postoperative examination by slitlamp microscopy was performed for 3 days after surgery. Rabbit eyes were excised and examined for histopathology with hematoxylin and eosin staining. Immunohistochemical analysis for interleukin (IL)-8 was performed.

RESULTS

Diffuse lamellar keratitis-like inflammation composed mainly of neutrophils was reproduced by LPS instillation in rabbit eyes. In eyes with severe inflammation, IL-8 immunoreactivity was found in the stromal keratocytes and infiltrating neutrophils.

CONCLUSIONS

The major cell type in the DLK infiltration induced by LPS instillation in rabbit eyes was the neutrophil. Interleukin-8, a prototype of CXC chemokine produced by keratocytes and neutrophils, may contribute to the development of DLK.

Wiping microkeratome blades with sterile 100% alcohol to prevent diffuse lamellar keratitis after laser in situ keratomileusis

PURPOSE

To report our experience in preventing diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) by wiping the microkeratome blade with sterile 100% alcohol.

SETTING

Enaim Refractive Surgery Center, Jerusalem, Israel.

METHODS

Laser in situ keratomileusis was performed in 24 patients (48 eyes) on the same day by the same surgeon. The environment and instruments were identical in all cases. A new blade was used in both eyes of each patient. All blades were from the same batch and were randomly assigned to 2 groups. In the alcohol group, 12 blades were wiped with a Merocel surgical spear (Medtronic Solan) dipped in 100% alcohol and rinsed with balanced salt solution (BSS) before they were mounted in a Hansatome microkeratome (Bausch & Lomb Co.); in the control group, 12 blades were wiped with a Merocel surgical spear dipped in BSS and rinsed with BSS. All patients were examined on the first postoperative day.

RESULTS

Grade I to II DLK was diagnosed in 7 eyes of 4 patients in the control group (29%). No DLK was diagnosed in the alcohol group.

CONCLUSION

Wiping the microkeratome blade with 100% alcohol before mounting may remove a substance from the manufacturing or sterilization process that can cause DLK.

Bilateral diffuse lamellar keratitis following bilateral simultaneous versus sequential laser in situ keratomileusis

AIM

To determine the difference in the incidence of bilateral diffuse lamellar keratitis (DLK) in patients undergoing simultaneous versus sequential laser in situ keratomileusis (LASIK) as an indication of intrinsic risk for inflammation.

METHODS

A retrospective non-comparative case series of 1632 eyes that had undergone bilateral, simultaneous or sequential LASIK between April 1998 and February 2001 at a university based refractive centre by three surgeons. All cases that developed clinically evident DLK were identified and reviewed. In order to identify isolated cases and exclude those caused by environmental factors, when more than one patient in a given session developed DLK, the session was excluded. The main outcome measure was the incidence of unilateral and bilateral isolated, non-epidemic DLK.

RESULTS

Of 1632 eyes, 126 eyes (7.7%) of 107 patients developed at least grade 1 DLK. In six operating sessions, DLK was observed in more than one patient per session, and on this basis 13 patients were excluded. 16 of the 94 remaining patients developed DLK in both eyes (17.0%). Six of 41 patients (14.6%) in the simultaneous group, versus 10 of 53 patients (18.9%) in the sequential group developed bilateral DLK (p >0.5).

CONCLUSION

In isolated, non-epidemic bilateral DLK, a similar incidence was observed regardless of whether the surgery was simultaneous or sequential, suggesting an underlying intrinsic cause for DLK.

Corneal flap complications in refractive surgery: Part 1: development of an experimental animal model

PURPOSE

To report the outcome, learning curve, and complication rates of an experimental animal model for corneal flaps in refractive surgery.

SETTING

Magill Research Center for Vision Correction, Storm Eye Institute, Charleston, South Carolina, USA.

METHODS

Corneal flaps with a nasal or a temporal hinge were created in 190 eyes of 95 Dutch Belted rabbits using the Automated Corneal Shaper microkeratome (Bausch & Lomb Surgical). Diffuse lamellar keratitis (DLK) was induced by inoculating the corneal interfaces with 1 of 7 substances. Postoperatively, the eyes were examined with a slitlamp. Special emphasis was placed on corneal flap complications and the relationship between slipped flaps and hinge position and/or inoculation agent.

RESULTS

A good corneal flap was achieved in 174 eyes (92%). The eyes with a nasal hinge had a lower incidence of slipped flaps (14%) than eyes with a temporal hinge (37%) (P =.02).

CONCLUSION

With the animal model described, corneal flaps were created in a precise and reproducible way in more than 90% of eyes. Nasal hinged flaps showed less postoperative displacements than temporal hinged flaps and are adequate for further study.

Corneal flap complications in refractive surgery: Part 2: postoperative treatments of diffuse lamellar keratitis in an experimental animal model

PURPOSE

To induce diffuse lamellar keratitis (DLK) and investigate a prophylactic treatment with pharmacological agents.

SETTING

Magill Research Center for Vision Correction, Storm Eye Institute, Charleston, South Carolina, USA.

METHODS

In 100 eyes of 50 Dutch Belted rabbits, a nasal corneal flap was cut and the interface inoculated with Pseudomonas aeruginosa lipopolysaccharide endotoxin (n = 50) or Palmolive Ultra soap (n = 50). The eyes were randomly assigned to treatment with a mast-cell stabilizer, a nonsteroidal antiinflammatory drug (NSAID), a fluoroquinolone antibiotic agent, a corticosteroid, or left without treatment as a control. Slitlamp examinations and photographs were performed 1, 3, 5, and 7 days postoperatively, and DLK was graded by a masked observer from 0 (no DLK) to stage 4.

RESULTS

At the end of the study, 80 eyes were available for evaluation. Ninety-four percent of the untreated eyes developed DLK compared to 56% of eyes treated with NSAIDs and 63% of eyes treated with steroids (P<.05, Fisher exact test). The DLK rates with the mast-cell stabilizer and fluoroquinolone antibiotic agent were 86% and 76%, respectively. The DLK incidence in the latter 2 groups was not significantly different from that in the control eyes (P>.05, Fisher exact test).

CONCLUSIONS

Postoperative prophylactic treatment with NSAIDs and corticosteroids led to a statistically significantly lower incidence of postoperative DLK. The study demonstrated that corticosteroids and NSAIDs can be used to treat DLK after LASIK. While steroids are a generally accepted treatment for DLK, NSAIDS may offer an additional potent modality.

Diffuse lamellar keratitis: evaluation of etiology, histopathologic findings, and clinical implications in an experimental animal model

PURPOSE

To induce diffuse lamellar keratitis (DLK) and investigate the potential causative agents in an animal model.

SETTING

Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

In 70 eyes of 35 Dutch Belted rabbits, a corneal flap was cut and the interface randomly exposed to 1 of 7 substances: Pseudomonas aeruginosa endotoxin, 1 of 2 Staphylococcus aureus exotoxins, meibomian gland secretion, povidone-iodine 10%, Palmolive Ultra soap, and Klenzyme soap. Slitlamp examinations were performed 1, 3, 5, and 7 days postoperatively. The DLK was staged from 1 to 4. On day 7, the rabbits were killed and the eyes enucleated and processed for histopathologic examination.

RESULTS

At the end of the study, 54 eyes (46 exposed, 8 control) were available for evaluation. The 8 eyes studied concurrently in the control group remained clear and did not show interface inflammation. Thirty-one of 46 eyes (67%) treated with the various test substances developed DLK. The highest DLK rates were found with the cleaning soap Palmolive Ultra (100%; P =.022) and P. aeruginosa lipopolysaccharide endotoxin (90%; P =.026).

CONCLUSIONS

Interface inflammation was consistently induced in the animal model. All 7 agents caused DLK in at least some eyes. The histopathologic evaluation showed the morphologic profile of the marked inflammatory cellular reaction that occurred in almost all the specimens.

Incidence and outcomes of lasik with diffuse lamellar keratitis treated with topical and oral corticosteroids

PURPOSE

To analyze the incidence and clinical outcomes of patients developing diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) treated with topical and oral corticosteroids.

SETTING

Oregon Eye Institute, Eugene, Oregon, USA.

METHODS

A retrospective analysis of the last consecutive 1000 LASIK cases was performed. Eyes developing stage 3 DLK or at risk for progressing to stage 3 were treated with a combination of high-dose prednisolone acetate 1% and oral prednisone and evaluated for corneal scarring, loss of best spectacle-corrected visual acuity (BSCVA), and deviation from the intended refractive outcome.

RESULTS

Diffuse lamellar keratitis developed in 40 eyes (4%). It progressed to stage 3 in 7 eyes (17%). Oral and topical steroids were used in 22 eyes (55%). The mean variation from the desired refractive outcome was 0.14 diopter +/- 0.53 (SD). There were no instances of corneal scarring or permanent loss of BSCVA. No eye had interface irrigation.

CONCLUSIONS

Treatment of severe DLK with high-dose topical and oral corticosteroids produced excellent results without flap lifting and interface irrigation.

Diffuse Lamellar Keratitis and Flap Margin Epithelial Healing After Laser in situ Keratomileusis

PURPOSE

To evaluate whether wound healing of the corneal epithelium at the flap margin influences development of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK).

METHODS

We examined prospectively 1928 eyes of 994 patients after LASIK. Condition of wound healing at the flap margin 1 day after LASIK was graded as gutter score from 0 to 3, according to the extent of fluorescein staining. Existence of DLK, gutter score, and the location of DLK and gutter were evaluated.

RESULTS

Sixty-eight eyes (3.5%) developed DLK. The average gutter score was significantly higher in patients with DLK compared to those without DLK (P<.001). The location of DLK was identical to the location of gutter in 44 eyes (77.2%).

CONCLUSION

Disruption of integrity of the epithelial barrier function at the flap margin was associcated with diffuse lamellar keratitis after laser in situ keratomileusis.

Phototherapeutic keratectomy for the treatment of diffuse lamellar keratitis

We report a case of laser in situ keratomileusis in which a patient with recurrent diffuse lamellar keratitis (DLK) recalcitrant to standard therapy was successfully treated with phototherapeutic keratectomy (PTK). The PTK was used to ablate both surfaces of the flap interface with the goal of removing DLK-inciting agents. The resultant sustained decrease in DLK suggests PTK is an effective therapy option.

Flap and interface complications in LASIK

Flap complications using first-generation microkeratomes, such as the Automated Corneal Shaper, were reported in 2.5% (27 of 1,062 eyes). With modern microkeratomes, such as the Hansatome, keratotomy-related complications dropped to 0.16% (46 of 28,201 eyes). Postoperative flap complications, such as flap slippage, occurred in 1.42% (21 of 1,418 eyes), most of them during the first hour after surgery. Interface complications are a new diagnostic entity as the interface between flap and stroma presents an empty space where fluid or cells can accumulate. Diffuse lamellar keratitis usually occurs within the first postoperative days but may also develop later on, triggered, eg, by recurrent corneal erosion. Epithelial ingrowth is a rare complication caused rather by postoperative invasion than by intraoperative implantation, which suggests that the quality of the flap edge and its apposition are very important. Interface fluid is a rare but important phenomenon related to steroid-induced glaucoma but presenting with falsely low tonometry readings.

Cleaning Solutions as a Cause of Diffuse Lamellar Keratitis

PURPOSE

To assess the capability of two microkeratome cleaning solutions in causing diffuse lamellar keratitis (DLK) in a rabbit model of laser in situ keratomileusis (LASIK).

METHODS

Two cleaning solutions (Palmolive 2:100 and Cidezyme 2:250) were tested. These solutions were diluted with balanced salt solution according to directions from the Hansatome microkeratome manual. Two additional solutions were prepared using an additional ten-fold dilution, creating a total of four study solutions. A LASIK flap was created in one eye each of 25 rabbits using the ALK Chiron microkeratome. The rabbits were divided into five study groups. The flaps were reflected and a drop of one of the study solutions (or BSS, control group) was placed on the interface. After 1 minute, the solution was washed out from the interface and the flap was repositioned. The eyes were examined at the slit lamp on postoperative days 1, 2, 3, 5, and 7.

RESULTS

In 12 eyes, a flap displacement was identified. Four eyes showed flap retraction and five others, epithelial ingrowth in flap margins. The incidence of these events did not differ among groups. Thirteen eyes were then evaluated for DLK. No DLK-like interface inflammation was seen in the studied eyes.

CONCLUSION

The cleaning solutions, when diluted as recommended by the microkeratome manufacturer, when in contact with the corneal stroma, and provided that the interface was washed with BSS did not cause DLK interface inflammation in rabbit LASIK models.

Treatment of interface keratitis with oral corticosteroids

PURPOSE

To describe the results of treating interface keratitis using a combination of intensive topical and oral corticosteroids.

SETTING

Casey Eye Institute, Portland, Oregon, USA.

METHODS

Thirteen eyes treated for grade 2 to 3 interface keratitis using an oral corticosteroid (prednisone 60 to 80 mg) as well as an hourly topical corticosteroid were retrospectively reviewed. The best corrected visual acuity (BCVA) was used as an objective guide of whether to treat with intense topical and oral corticosteroids, flap irrigation, or both. Predisposing factors such as intraoperative epithelial defects or a history of severe allergies or atopy were also looked for.

RESULTS

All 13 eyes responded favorably to the combination of intensive topical and oral corticosteroids and had a BCVA of 20/20 after the keratitis resolved. In 6 eyes (46%), the patients had a history of severe seasonal allergies. One day postoperatively, 3 eyes (23%) had an epithelial defect and 2 eyes (15%), lint particles or debris embedded in the interface. With oral corticosteroid use, 3 patients (23%) noted mild stomach irritation and 2 (15%) noted nervousness. All 5 side effects resolved without sequelae. No patient developed a serious side effect.

CONCLUSIONS

A short, intense course of an oral corticosteroid was an effective treatment in patients with grade 2 or higher interface keratitis when combined with a topical corticosteroid administered hourly. The BCVA is a helpful objective measure of the severity of interface keratitis and can be used to guide the clinician in the therapeutic strategy.