Cases Of Diffuse Lamellar Keratitis Research Articles

Late-onset Diffuse Lamellar Keratitis in the Context of Conjunctivitis Related to COVID-19: Case Report

Purpose: To report a case of diffuse lamellar keratitis (DLK) occurring 23 years after laser in situ keratomileusis (LASIK), coinciding with a recent diagnosis of conjunctivitis related to coronavirus disease 2019 (COVID-19) . Methods: A 47-year-old woman had LASIK in 2000 and developed conjunctivitis related to COVID-19 in March 2022. In February 2023, she presented with 5 days of decreased vision (corrected distance visual acuity 20/25), photophobia, and glare in her right eye. She was diagnosed as having stage I DLK in the right eye based on corneal inflammatory infiltrates in the peripheral flap interface. Results: Topical steroids improved the patient's symptoms and resolved the inflammatory infiltrates within 2 months with a final corrected distance visual acuity of 20/20. Conclusions: This report describes a rare case of DLK occurring more than 20 years after LASIK. It is important to consider DLK even outside of the early postoperative period after LASIK or another lamellar interface–based procedure. In this case, conjunctivitis related to COVID-19 may have played a role in immune dysregulation and the development of DLK. [ Journal of Refractive Surgery Case Reports. 2024;4(1):e11–e14.]

Five-Year Incidence, Management, and Visual Outcomes of Diffuse Lamellar Keratitis after Femtosecond-Assisted LASIK

Femtosecond (FS) lasers initially had a higher incidence of diffuse lamellar keratitis (DLK) compared with microkeratome flap creation. It has been theorized that higher-frequency lower-energy (HFLE) FS lasers would reduce the incidence of DLK. Our study sought to evaluate the incidence of newer HFLE FS lasers with pulse frequencies above 60 kHz. It was a retrospective case-control study evaluating the incidence of DLK following flap creation with one of three FS lasers (AMO iFs, WaveLight FS200, Zeiss VisuMax). Uncomplicated LASIK cases were included as the control group (14,348 eyes) and cases of DLK were recorded in the study group (637 eyes). Of the 637 cases of DLK, 76 developed stage II, 25 progressed to stage III, and only three developed stage IV DLK. The overall incidence rate of DLK was 4.3%; it has fallen with the invention of newer HFLE FS lasers and is approaching the DLK incidence rates of DLK with microkeratome.

Early Surface Ablation on Aborted LASIK Flaps

To report the outcomes of a series of 16 patients who had secondary surface ablation within 4 weeks of an aborted femtosecond laser-assisted in situ keratomileusis (FS-LASIK) procedure. A retrospective chart review of electronic medical record data from 2011 to 2015 was performed to identify eyes of patients who had an aborted FS-LASIK procedure followed by secondary surface ablation (photorefractive keratectomy or laser epithelial keratomileusis) within 4 weeks of the primary procedure. Patients were required to have at least three postoperative visits to be included in the study. The review identified 20 aborted FS-LASIK procedures of 7,142 eyes (0.003%), of which 16 met the inclusion criteria. The most common reasons for abortion were incomplete (10) and decentered (3) flaps. Thirteen of 16 eyes were treated within 2 weeks. A total of 11 of 16 eyes achieved uncorrected distance visual acuity (UDVA) of 20/20, 13 of 16 achieved UDVA of 20/25 or better, and 15 of 16 had a corrected distance visual acuity (CDVA) of 20/20. There were no intraoperative complications during the second procedure and there were no cases of diffuse lamellar keratitis. One patient developed postoperative haze with a CDVA of 20/25 and was lost to follow-up. This case series indicates that early surface ablation (within 4 weeks) after an aborted FS-LASIK procedure may be performed with good visual outcomes. [J Refract Surg. 2019;35(2):121-125.].

Intraoperative and early postoperative flap-related complications of laser in situ keratomileusis using two types of Moria microkeratomes

The purpose of this study is to describe the incidence, management, and visual outcomes of intraoperative and early postoperative flap-related complications of laser in situ keratomileusis (LASIK) surgery using two types of Moria M2 microkeratomes. This retrospective analysis was performed on 806 primary LASIK cases. The intraoperative and early postoperative flap-related complications were identified and categorized according to type of Moria microkeratome. There were 52 intraoperative and early postoperative complications--one case of partial flap (0.124 %), one case of free flap (0.124 %), one case of small flap (0.124 %), 13 cases of epithelial defect (1.61 %), 12 cases of flap striae (1.49 %), 10 cases of diffuse lamellar keratitis (1.24 %), 10 cases of interface debris (1.24 %), three cases of epithelial ingrowth (0.37 %), and one case of microbial infection (0.124 %). The overall incidence of flap complications was 6.45 %. There were 27 right eye (6.73 %) and 25 left eye (6.17 %) complications. The incidence of complications with the Moria automated metallic head 130 microkeratome was 4.22 % and with the Moria single-use head 90 microkeratome was 2.23 %. We observed one culture-negative interface abscess which was cured with surgical cleaning and intensive medical treatment. The most common complication encountered was epithelial defects, followed by flap striae. Our study showed that LASIK with a microkeratome has a relatively low incidence of intraoperative and early postoperative flap complications. The authors have no financial interest in any of the issues contained in this article and have no proprietary interest in the development of marketing of or materials used in this study.

IntraLase Femtosecond Laser vs Mechanical Microkeratomes in LASIK for Myopia: A Systematic Review and Meta-analysis

To evaluate the safety, efficacy, and predictability of IntraLase (Abbott Medical Optics) femtosecond laser-assisted compared to microkeratome-assisted myopic LASIK. A comprehensive literature search of Cochrane Library, PubMed, and EMBASE was conducted to identify relevant trials comparing LASIK with IntraLase femtosecond laser to LASIK with microkeratomes for the correction of myopia. Meta-analyses were performed on the primary outcomes (loss of ≥2 lines of corrected distance visual acuity [CDVA], uncorrected distance visual acuity [UDVA] 20/20 or better, manifest refraction spherical equivalent [MRSE] within ±0.50 diopters [D], final refractive SE, and astigmatism), and secondary outcomes (flap thickness predictability, changes in higher order aberrations [HOAs], and complications). Fifteen articles describing a total of 3679 eyes were identified. No significant differences were identified between the two groups in regards to a loss of ≥2 lines of CDVA (P=.44), patients achieving UDVA 20/20 or better (P=.24), final UDVA (P=.12), final mean refractive SE (P=.74), final astigmatism (P=.27), or changes in HOAs. The IntraLase group had more patients who were within ±0.50 D of target refraction (P=.05) compared to the microkeratome group, and flap thickness was more predictable in the IntraLase group (P<.0001). The microkeratome group had more epithelial defects (P=.04), whereas the IntraLase group had more cases of diffuse lamellar keratitis (P=.01). According to the available data, LASIK with the IntraLase femtosecond laser offers no significant benefits over LASIK with microkeratomes in regards to safety and efficacy, but has potential advantages in predictability.

Late‐Onset Diffuse Lamellar Keratitis associated with cataract phacoemulsification

AbstractPurpose Diffuse lamellar keratitis (DLK) is characterized by the presence of a diffuse inflammatory infiltrate localized at the laser in situ keratomileusis interface, with a non‐infectious etiology. Most cases of DLK occur within the first week following surgery but late‐onset DLK has been associated with inflammatory conditions such as iritis, viral keratoconjunctivitis or interstitial keratitis; and it can occur even years after LASIK.Methods Prospective, interventional, single case report. A 67‐year‐old male patient, who had undergone bilateral LASIK 13 years earlier, developed an episode of DLK on the third day of the postoperative‐cataract surgery on his left eye (LE). Slit‐lamp biomicroscopy and optical coherence tomography (anterior segment mode) were performed to demonstrate the presence of highly‐reflective multifocal infiltrates and the absence of fluid at the flap interface. The patient was treated with intensive topical corticosteroids.Results Treatment with topical 1.0% prednisolone acetate was instituted and continued for months, with improvement in patient symptoms and visual acuity.Conclusion This is a case of DLK with an extremely delayed onset, which emphasizes the importance of following‐up of these patients not only in the early postoperative period.

Late-onset Severe Diffuse Lamellar Keratitis Associated With Uveitis After LASIK in a Patient With Ankylosing Spondylitis

To report a case of diffuse lamellar keratitis (DLK) associated with acute anterior uveitis that occurred 3 years after uneventful LASIK in a patient with a history of ankylosing spondylitis and recurrent acute anterior uveitis. A 36-year-old man presented with pain and decreased vision in the left eye. Left eye visual acuity was 20/100. He had undergone bilateral LASIK 3 years prior to presentation to treat moderate myopia. Slit-lamp examination revealed aqueous flare and cells, vertical corneal folds, and cell aggregates at the central interface. Flattening and thinning of the cornea were observed with Pentacam (Oculus Optikgeräte GmbH). Diffuse lamellar keratitis stage III was diagnosed and intensive corticosteroid and anticollagenolytic treatment was started with satisfactory results. Acute anterior uveitis may be a predisposing factor for late-onset DLK after LASIK surgery. Indication of LASIK in patients at high risk of developing recurrent flares of acute anterior uveitis, such as those with spondyloarthropathies, should be carefully considered.

Outbreak of diffuse lamellar keratitis caused by marking-pen toxicity

To examine the evidence that a series of cases of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) was caused by a type of marker pen. Eye Institute, Auckland, New Zealand. During a 10-week period, 522 consecutive LASIK procedures were performed using a 60 Hz IntraLase femtosecond laser (IntraLase Corp.) to create the LASIK flap and a 217Z 100 Hz excimer laser (Bausch & Lomb) to perform the refractive ablation. As standard practice, a marking pen was used to enable accurate flap realignment. Three weeks after a sudden increase in the incidence of DLK was identified, one of the 5 surgeons performed 5 consecutive bilateral cases using the marking pen in the right eyes but not in the left eyes. Of the 522 LASIK cases (119 without marking pen, 403 with marking pen), DLK developed in 49 (9.4%). No eye treated without the marking pen developed DLK; of those in which the marking pen was used, 49 (12.2%) developed DLK (P<0.0001, Fischer exact test; odds ratio, 27). In the 5 consecutive bilateral cases in which the marking pen was used in the right eye but not the left eye, 4 right eyes and no left eye developed DLK (P=0.03). Forty-five of the 49 eyes with DLK quickly recovered. The other 4 developed central toxic keratopathy. There is strong statistical evidence that the marking pen was a factor in the occurrence of DLK.

Diffuse lamellar keratitis after laser in situ keratomileusis associated with surgical marker pens

To describe a series of cases of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) associated with intraoperative use of a surgical marker pen. Singapore National Eye Centre, Singapore, Singapore. A review of all 115 patients (125 eyes) who had myopic LASIK from July 23 to July 26, 2007, was performed to determine whether eyes in which the Codman surgical marker pen (Johnson & Johnson Medical) was used intraoperatively developed postoperative DLK. Nine of 12 eyes that had LASIK or flap relifting with a Codman surgical marker pen developed grade 1 to grade 3 DLK on the first postoperative day. The 113 other eyes that had LASIK in the same week with another brand of surgical marker pen (Securline, Precision Dynamics Corp.) did not develop DLK. All eyes with DLK were treated with intensive topical steroid therapy. The DLK resolved in 2 eyes after the steroid treatment; 7 eyes required flap relifting with interface irrigation. One month postoperatively, 6 eyes with DLK had an uncorrected visual acuity of 6/7.5 or better. Two eyes developed central corneal scarring with consecutive hyperopia with a best corrected visual acuity of 6/12 after 1 month. There was a strong association between the occurrence of DLK after LASIK with the use of the Codman surgical marker pen. One or more constituents of the ink in the Codman pen may have been responsible for this series of cases.

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

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

Diffuse lamellar keratitis complicating laser in situ keratomileusis

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

Benefits and Side Effects of Bandage Soft Contact Lens Application after LASIK: A Prospective Randomized Study

To evaluate benefits and side effects of bandage soft contact lens (BSCL) insertion after LASIK in relation to patients' characteristics. Prospective, randomized, bicenter comparative investigational trial. One hundred patients (200 eyes) with myopia and/or myopic astigmatism. Each patient underwent consecutive (Marburg, Germany) or simultaneous (Mainz, Germany) bilateral LASIK. At the end of the procedure, the first treated eye received a drop of ofloxacin and dexamethasone, patch, and transparent protective shield for 2 to 4 hours. The fellow eye received in addition a BSCL, soaked in the same eyedrops for 20 to 24 hours. Schirmer II test results, first-day uncorrected visual acuity (UCVA), and tolerance of contact lens wear (poor, moderate, good) were recorded. Patients' subjective preference for the BSCL on the first postoperative day was graded as more comfortable than fellow eye, no difference, or less comfortable. Three months after surgery, the corneal flap was photographed in retroillumination for objective evaluation of microstriae. Statistical significance was determined using the Kruskal-Wallis 1-way analysis of variance on ranks test. Fifty-four percent of patients felt discomfort in the eye that had the BSCL (contra-BSCL subgroup), whereas 27% enjoyed having a BSCL (pro-BSCL subgroup). The remaining 19% felt no difference. The average Schirmer II value was 16.6 mm (+/-7.7) in the pro-BSCL subgroup, 14.9 mm (+/-6.4) in the no difference subgroup, and 12.3 mm (+/-7.7) in the contra-BSCL subgroup. There was a female preponderance in the contra-BSCL (39:15) and no difference (15:6) subgroups. A preoperative history of poor contact lens tolerance was recorded in 50% of the contra-BSCL subgroup patients; 41%, no difference; and 33%, pro-BSCL. Postoperative parameters such as first-day UCVA, number of eyes with microstriae, folds requiring stretching, or cases of diffuse lamellar keratitis did not differ significantly. Eyes with flap microstriae had a significantly deeper mean ablation (114.5 microm [range, 52-146 microm]) than eyes without any flap abnormalities (75.4 microm [39-120 microm]). No significant differences were found between the consecutive and simultaneous groups. The majority of patients did not experience better postoperative comfort from the application of a BSCL. Only 27% of patients reported more comfort from postoperative BSCL use. The latter have better tear film characteristics and a history of less difficulty with contact lenses preoperatively. A BSCL does not protect from the occurrence of microstriae.

The epidemiology of diffuse lamellar keratitis.

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

Resultado visual comparativo entre dois aparelhos de excimer laser: Summit Apex Plus e Aesculap-Meditec Mel 70 em cirurgia de miopia e astigmatismo

OBJETIVO: Comparar o resultado visual de uma série de casos de LASIK para correção de miopia e astigmatismo utilizando dois aparelhos de excimer laser de diferentes fabricantes. MÉTODOS: Foram estudados 22 olhos de 11 pacientes com miopia de -0,50 a -11,25 e astigmatismo de -0,50 a -4,75 no período de março de 2000 a julho de 2001. Os pacientes realizaram LASIK num olho com o excimer laser da Summit Apex Plus e no olho contralateral com o excimer laser Mel 70 (Aesculap-Meditec). RESULTADOS: A média do equivalente esférico (EE) pré-operatório foi de -4,74 no Summit, -4,8 no Mel 70, do pós-operatório de 1, 3, e12 meses foi 0,54; 0,58 e 0,014 no Summit e 0,02; 0,04 e -0,43 no Mel 70. Não houve diferença estatística significante entre eles em relação à acuidade visual sem correção (AVSC), acuidade visual com correção (AVCC), equivalente esférico (EE) nos tempos pré e pós-operatórios. Após 12 meses, 90,9% ficaram com AVCC=20/20 no Summit e 73% no Mel 70, 81,8% com AVSC =20/20 no Summit e 45,5% no Mel 70. Em relação ao EE aos 12 meses, 73% no Summit ficaram entre ±1,00D e 82% no Mel 70. Em relação à perda de 1 ou mais linhas tivemos 27,3% no Mel 70 e 9% no Summit. Complicações: 9% (2) casos de ceratite difusa lamelar e 45,5% de fibrose leve da borda do flap no Mel 70 em 1 ano de pós-operatório. CONCLUSÃO: Consideramos os 2 lasers eficientes e seguros para o tratamento de miopia e astigmatismo.

Late-onset diffuse lamellar keratitis

Background: Diffuse lamellar keratitis (DLK) is marked by the presence of diffuse or multifocal infiltrates confined to the laser in situ keratomileusis (LASIK) interface. These infiltrates are culture-negative, and the etiology is thought to be noninfectious. Most cases of DLK occur within the first week or 2 following surgery. Cases: We described 2 cases of DLK that occurred 3 months after LASIK. These patients were treated with intensive topical corticosteroids. Results: Treatment with topical corticosteroid was instituted, with rapid improvement in patient symptoms, visual acuity, and slit-lamp biomicroscopic findings. Conclusion: DLK may occur as late as 3 months after LASIK.

Late onset diffuse lamellar keratitis

Background: Diffuse lamellar keratitis (DLK) is marked by the presence of diffuse or multifocal infiltrates confined to the laser in situ keratomileusis (LASIK) interface. These infiltrates are culture-negative, and the etiology is thought to be noninfectious. Most cases of DLK occur within the first week or two following surgery. Case: We describe two cases of diffuse lamellar keratitis that occurred 3 months after LASIK. These patients were treated with intensive topical corticosteroids. Results: We treated both patients with topical corticosteroids, with rapid improvement in patient symptoms, visual acuity, and slit-lamp biomicroscopy findings. Conclusion: DLK may occur three months after LASIK. Nippon Ganka Gakkai Zasshi

Diffuse Lamellar Keratitis 6 Months After Uneventful Laser in situ Keratomileusis

Diffuse lamellar keratitis after laser in situ keratomileusis (LASIK) typically occurs between 1 and 7 days after the procedure, and its etiologic factor(s) remain unknown. We describe a case of diffuse lamellar keratitis 6 months after uneventful LASIK in a 25-year-old woman. Slit-lamp microscopy showed a diffuse infiltrate confined to the interface, extending to the visual axis, with no other relevant findings. Late on-set diffuse lamellar keratitis was our provisional diagnosis and treatment with topical corticosteroids was instituted, with rapid response and improvement of the clinical signs and symptoms. This case supports the theory that a previously inert inciting agent could cause a delayed toxic or inflammatory response of the cornea several months after surgery.

Confocal Microscopy in Late-Onset Diffuse Lamellar Keratitis After Laser In Situ Keratomileusis

This article reports a case of diffuse lamellar keratitis, without exposure of the flap interface, that developed in a patient who underwent intraepithelial photorefractive keratectomy 1 year after bilateral LASIK. Confocal microscopy was performed in both eyes at the onset of the diffuse lamellar keratitis and after its resolution. In the eye with diffuse lamellar keratitis, abundant round structures (inflammatory cells) were present at the interface; these structures disappeared after the keratitis resolved and were not present in the contralateral eye at any time. These confocal microscopic findings further support the hypothesis that diffuse lamellar keratitis is a nonspecific inflammatory response in corneas with a lamellar interface.

Diffuse lamellar keratitis related to endotoxins released from sterilizer reservoir biofilms

Objective To investigate the risk factors and control mechanisms used to control the outbreak of diffuse lamellar keratitis (DLK) associated with laser in situ keratomileusis (LASIK) and examine the relationship between DLK and endotoxins released from sterilizer biofilm reservoirs. Design Clinic-based cohort and laboratory study. Participants All patients undergoing LASIK at our clinic from October 7, 1998 through August 31, 1999. The case definition was a diffuse infiltrate in the interface developing within the first week after surgery. Interventions Biofilm control in the sterilizer, changes in sterilizer, distilled water, instruments, and irrigating fluids. Main outcome measures The incidence of DLK after LASIK surgery. Results There were 983 evaluable patients, with three whose DLK status was not recorded. There were 52 cases of DLK. Burkholderia pickettii was isolated from the sterilizer reservoir. Potential risk factors and associations, for which there was no significant difference, included age and sex of the patients, surgeon, operating suite temperature or humidity, drapes used, saline solutions used, time of day the surgery was performed, and microkeratome use. Sterilizers 1 and 2, before biofilm control, were compared with sterilizer 3, after control. The relative risk was 9.4 (confidence limits [CL], 7.5–11.8) for sterilizer 1 versus 3 and 18.7 (CL, 11–32) for sterilizer 2 versus 3. Three cases occurred after biofilm control, but were sporadic in nature and associated with epithelial defects. Conclusions Clusters of DLK may be related to endotoxins released from gram-negative biofilms in sterilizer reservoirs. We experienced an outbreak of DLK affecting 52 patients and isolated B. pickettii from the sterilizer reservoir. Epidemiologic investigation showed that biofilm control in the sterilizer reservoirs was associated with a significant reduction in the development of DLK. We encourage any clinics that experience a cluster of DLK to consider microbiologic and epidemiologic investigation for the effectiveness of sterilizer biofilm control.