Cleaning Solutions as a Cause of Diffuse Lamellar Keratitis

Keratitis following laser refractive surgery: Clinical spectrum, prevention and management

Laser refractive surgery (LRS) is one of the most demanding areas of ophthalmic surgery and high level of precision is required to meet outcome expectations of patients. Post-operative recovery is of vital importance. Keratitis occurring after LRS can delay visual recovery. Both surface ablations [Photorefractive keratectomy (PRK)] as well as flap procedures [Laser in-situ keratomileusis (LASIK)/Small incision lenticule extraction] are prone to this complication. Reported incidence of post-LRS infectious keratitis is between 0% and 1.5%. The rate of infections after PRK seems to be higher than that after LASIK. Staphylococci, streptococci, and mycobacteria are the common etiological organisms. About 50–60% of patients present within the first week of surgery. Of the non-infectious keratitis, diffuse lamellar keratitis (DLK) is the most common with reported rates between 0.4% and 4.38%. The incidence of DLK seems to be higher with femtosecond LASIK than with microkeratome LASIK. A lot of stress is laid on prevention of this complication through proper case selection, asepsis, and use of improved protocols. Once keratitis develops, the right approach can help resolve this condition quickly. In cases of suspected microbial keratitis, laboratory identification of the organism is important. Most lesions resolve with medical management alone. Interface irrigation, flap amputation, collagen cross-linking and therapeutic penetrating keratoplasty (TPK) are reserved for severe/non-resolving cases. About 50–75% of all infectious keratitis cases post LRS resolve with a final vision of 20/40 or greater. Improved awareness, early diagnosis, and appropriate intervention can help limit the damage to cornea and preserve vision.

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.

Late Onset Diffuse Lamellar Keratitis as a Result of the Toxic Effect of Ecballium Elaterium Herb

PURPOSE

To report a case of late onset diffuse lamellar keratitis (DLK) 11 months after LASIK due to Ecballium elaterium exposure.

METHODS

A 25-year-old man underwent bilateral LASIK. No complications were observed during the early postoperative period.

RESULTS

Eleven months after LASIK surgery, grade II DLK was diagnosed after an Ecballium elaterium herb seed burst and splashed into the patient's left eye. Topical steroid treatment was administered and DLK healed in 2 weeks without complication.

CONCLUSIONS

Although DLK typically develops in the early postoperative period, it could occur months after surgery. Treatment should begin as soon as DLK is diagnosed.

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.

Moria M2 Single Use Microkeratome Head in 100 Consecutive LASIK Procedures

PURPOSE

To evaluate the safety and efficacy of the Moria M2 single use 130 microkeratome head in consecutive LASIK procedures for correction of myopia and myopic astigmatism.

METHODS

One hundred eyes of 55 patients underwent LASIK in which the flaps were created with the Moria M2 microkeratome using the single use 130 head and excimer laser ablation was done with the Allegretto Wave-light laser. Flap parameters measured were: thickness, diameter, hinge length, and overall quality. Preoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, wavefront aberrations, and low contrast sensitivity were compared to postoperative values at 6-month follow-up.

RESULTS

Mean flap thickness was 145 +/- 17.5 microm, mean flap diameter was 8.5 +/- 0.40 mm, and mean hinge cord length was 4.05 +/- 0.35 mm. At 6-month follow-up, UCVA improved from 20/200 (+/-0.24) to 20/18.5 (+/-0.12) and BSCVA improved from 20/20.5 (+/-0.18) to 20/17.5 (+/-0.11).

CONCLUSIONS

The Moria M2 single use 130 microkeratome head appears to be safe and effective in performing LASIK procedures.

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.

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.

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.