Serratia Marcescens corneal ulcer as a complication of orthokeratology

Orthokeratology Associated Microbial Keratitis

Purpose

To report the clinical course, microbiologic findings, treatment, and outcomes of overnight orthokeratology associated microbial keratitis.

Methods

Four cases of overnight orthokeratology associated microbial keratitis are reported.

Results

Four patients aged 14–23 years (mean 18 years) who had central or paracentral corneal ulcers were included. Visual acuity at presentation ranged from 20/30 to hand motion. In all cases Pseudomonas aeruginosa was cultured from corneal scrapings or storage solution. In all patients the infection resolved with intensive topical antimicrobial treatment. Final best-corrected visual acuity ranged from 20/25 to 20/200 according to the location, size, and density of the corneal scar, which complicated all cases.

Conclusions

Infectious keratitis is a significant, visual threatening complication of overnight orthokeratology. Eye care practitioners should be aware of this complication and educate their patients of the importance of lens hygiene and prompt medical care when symptoms or signs of keratitis appear.

The Safety of Orthokeratology--A Systematic Review

Objectives:

The aim of this review is to evaluate the ocular safety of orthokeratology (OrthoK) treatment of myopia correction and retardation.

Data Sources:

Clinical studies published in English and Chinese were identified from MEDLINE, EMBASE CNKI, CQVIP, and WANFANG DATA (all from 1980 to April 2015). The reference lists of the studies and the Science Citation Index were also searched.

Selection Criteria:

Relevant clinical studies including case series, case reports, patient/practitioner surveys, retrospective and prospective cohort studies, and clinical trials were all included in the review. The material of OrthoK lenses was limited to gas-permeable lens.

Main Results:

This review incorporated a total of 170 publications, including 58 English and 112 Chinese literature. The risk of microbial keratitis in overnight OrthoK was similar to that of other overnight modality. The most common complication was corneal staining. Other clinically insignificant side effects included epithelial iron deposit, prominent fribrillary lines, and transient changes of corneal biomechanical properties. There was no long-term effect of OrthoK on corneal endothelium.

Conclusions:

There is sufficient evidence to suggest that OrthoK is a safe option for myopia correction and retardation. Long-term success of OrthoK treatment requires a combination of proper lens fitting, rigorous compliance to lens care regimen, good adherence to routine follow-ups, and timely treatment of complications.

Corneal Ring Infiltrates Caused by Serratia marcescens in a Patient with Human Immunodeficiency Virus

PURPOSE

To describe corneal ring infiltrates caused by Serratia marcescens in a patient with human immunodeficiency virus (HIV-1) who wore contact lenses.

METHODS

A case study of a patient with keratitis due to an infection caused by S. marcescens and exhibiting corneal ring infiltrates was reviewed for history, clinical manifestation, microscopic study, and management.

RESULTS

A 29-year-old man who had a history of contact lens wear and HIV-1 infection was admitted to hospital because of blurred vision, redness, and corneal infiltrates in the shape of a ring in the left eye. The visual acuity (VA) in both eyes was hand movement (uncorrected). Corneal scrapings were performed. The culture results of the corneal specimens revealed S. marcescens. The culture results of the contact lens disclosed the same organism. The corneal ulcer responded well to treatment with topical gentamycin sulfate 14 mg/ml. The final VA remained hand movement.

CONCLUSIONS

S. marcescens can cause ring infiltrates in a HIV-1 patient who wears contact lenses. The treatment result for S. marcescens keratitis in a HIV-1 patient who wore contact lenses was favorable after intensive use of fortified topical antibiotics.

Orthokeratology lens related infections

Orthokeratology is a reversible technique that temporarily changes the curvature of the cornea with the aim of addressing refractive errors. The United States Food and Drug Administration (FDA) granted approval for using reverse geometry contact lenses to correct myopia without any age restriction. Information from the pre-market applications to the FDA was rated as level II evidence. Another unapproved use of overnight orthokeratology is for the prevention of myopic progression. Although orthokeratology is advocated to reduce myopic progression, there are limited long-term studies with substantial evidence of its benefits. Much of this evidence comes from non-robust experimental studies using historical or self-selected controls with relative high dropout rates. Although some positive results have been published in temporarily reducing the myopic refractive error and its progression, the use of these lenses can be associated with serious complications such as microbial keratitis. Microbial keratitis is a potentially vision-threatening adverse response associated with contact lens wear. In fact, contact lens wear has been shown to be the predominant risk factor of microbial keratitis in some developed countries. Most of the published cases on overnight orthokeratology related microbial keratitis occurred in children or adolescents. Parents considering orthokeratology must make an informed decision about its temporary benefit and its potential for permanent loss of vision. The ophthalmic community should be reminded of the potential complications of orthokeratology.

Risk factors, microbiological profile, and treatment outcomes of pediatric microbial keratitis in a tertiary care hospital in Hong Kong

PURPOSE

To report the risk factors and microbiological profile of pediatric microbial keratitis cases in a tertiary care hospital in Hong Kong.

DESIGN

Retrospective study.

METHODS

Case records of patients <18 years old with microbial keratitis were reviewed over a period of 10 years, between January 2001 and December 2010. Risk factors, microbiological profile, and treatment outcomes were analyzed.

RESULTS

Overall, 18 patients (13 female, 5 male) with unilateral microbial keratitis were included. The mean age was 12.4 years (range: 3-17 years). The most commonly associated risk factor was contact lens wear (15, 83.3%). Seven cases (38.8%) were associated with orthokeratology lenses. Two cases (11.1%) were related to intrinsic keratopathy and 1 case (5.5%) was infected secondary to trauma. Microbiological culture was positive in 16 cases (88.8%). Overall, Pseudomonas sp. was the most commonly isolated organism (10/16, 62.5%), followed by coagulase-negative Staphylococcus (5/16, 31.2%) and Corynebacterium sp. (2/16, 12.5%). All cases responded to intensive medical management with topical antibiotics. One case with posttraumatic keratitis required stepped surgeries with initial tectonic penetrating keratoplasty followed by lens aspiration and retinal detachment repair. At the last follow-up, 13 out of 17 eyes (76.5%) had best-corrected visual acuity ≥20/40.

CONCLUSIONS

Contact lens wear was the most commonly encountered risk factor for the occurrence of microbial keratitis in the pediatric age group in our setting. Orthokeratology remains one of the leading causes of contact lens-related infections. The majority of the cases responded to medical management.).

Quantitative evaluation of night vision and correlation of refractive and topographical parameters with glare after orthokeratology

PURPOSE

To evaluate night vision disturbance and investigate correlations between pre- and post-treatment parameters and glare scores in orthokeratology patients.

METHODS

Twenty-eight right eyes of 28 patients were enrolled in this study. Corneal topography and a night vision test (NVT) to evaluate the extent of glare were performed after orthokeratology. From the corneal topography, two indices [surface regularity index (SRI) and surface asymmetry index (SAI)] were calculated. Fourier analysis was performed on the topographic data from the central 6 mm, and data were decomposed into asymmetric and higher order components for analysis.

RESULTS

There was no correlation between the glare score and pre-treatment keratometric value, pre-treatment cylinder, post-treatment sphere, and post-treatment cylinder. However, there was a statistically significant correlation between pre-treatment sphere and glare score (Pearson correlation coefficient, r = -0.54, p < 0.01). SRI and SAI significantly correlated with glare score (SRI: r = 0.52, p < 0.01, SAI: r = 0.41, p < 0.05). Higher order and asymmetric components were also significantly correlated with glare score (asymmetry: r = 0.61, p < 0.01, higher order: r = 0.67, p < 0.001).

CONCLUSIONS

The glare score was significantly correlated with corneal irregularity, and appeared to be a beneficial parameter for assessment of night vision performance in patients receiving orthokeratology.

Microbial contamination of contact lenses, lens care solutions, and their accessories: a literature review

PURPOSE

A contact lens (CL) can act as a vector for microorganisms to adhere to and transfer to the ocular surface. Commensal microorganisms that uneventfully cohabitate on lid margins and conjunctivae and potential pathogens that are found transiently on the ocular surface can inoculate CLs in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva to produce inflammation or infection.

METHODS

The literature was reviewed and used to summarize the findings over the last 30 years on the identification, enumeration, and classification of microorganisms adherent to CLs and their accessories during the course of normal wear and to hypothesize the role that these microorganisms play in CL infection and inflammation.

RESULTS

Lens handling greatly increases the incidence of lens contamination, and the ocular surface has a tremendous ability to destroy organisms. However, even when removed aseptically from the eye, more than half of lenses are found to harbor microorganisms, almost exclusively bacteria. Coagulase-negative Staphylococci are most commonly cultured from worn lenses; however, approximately 10% of lenses harbor Gram-negative and highly pathogenic species, even in asymptomatic subjects. In storage cases, the incidence of positive microbial bioburden is also typically greater than 50%. All types of care solutions can become contaminated, including up to 30% of preserved products.

CONCLUSIONS

The process of CL-related microbial keratitis and inflammation is thought to be preceded by the presence or transfer or both of microorganisms from the lens to the ocular surface. Thus, this detailed understanding of lens-related bioburden is important in the understanding of factors associated with infectious and inflammatory complications. Promising mechanisms to prevent bacterial colonization on lenses and lens cases are forthcoming, which may decrease the incidence of microbially driven CL complications.

Corneal sensation after overnight orthokeratology

PURPOSE

The purpose of this study was to investigate the influence of overnight orthokeratology on corneal sensation.

METHODS

A prospective study was conducted in 34 eyes of 17 patients undergoing overnight orthokeratology. Their ages ranged from 21 to 33 years (23.5 +/- 3.2 years, mean +/- standard deviation). The logarithm of minimum angle of resolution of uncorrected visual acuity at baseline ranged from 0.22 to 1.52 (0.71 +/- 0.32), and myopic refractive error ranged from -1.00 to -4.00 D (-2.15 +/- 0.90 D). Corneal sensation was measured using the Cochet-Bonnet esthesiometer before and 3 months after the start of treatment, and each eye was tested at 5 different corneal locations: one central point and 4 peripheral points at the superior, inferior, temporal, and nasal positions 2 mm away from the limbus.

RESULTS

Overnight orthokeratology significantly reduced corneal sensation from 58.24 +/- 6.14 mm at baseline to 49.12 +/- 13.90 mm at 3 months after the start of treatment at the central point (P = 0.0003, Wilcoxon signed-rank test), from 58.24 +/- 6.14 to 47.65 +/- 14.37 mm at the superior point (P = 0.0002), from 57.50 +/- 6.43 to 48.09 +/- 14.82 mm at the inferior point (P = 0.0004), from 58.24 +/- 6.14 to 50.44 +/- 13.73 mm at the temporal point (P = 0.0009), and from 57.65 +/- 6.54 to 48.68 +/- 14.84 mm at the nasal point (P = 0.0022). There were no significant differences in corneal sensation among these 5 points 3 months after the treatment (P = 0.9549, Kruskal-Wallis test). The induced change in corneal sensation at the central cornea was further analyzed in relation to the amount of myopic correction. There was no significant correlation between the loss of corneal sensation and the amount of myopic correction (r = -0.211, P = 0.2245, Spearman rank correlation).

CONCLUSIONS

Overnight orthokeratology significantly reduced corneal sensation at both central and peripheral locations, and the reduction was not correlated with the amount of myopic correction. At present, the clinical significance of this sensory loss is not clear, but practitioners should take this effect into account in the practice of orthokeratology.

Morphologic changes in cat epithelium following continuous wear of orthokeratology lenses: A pilot study

PURPOSE

To investigate the sequence of morphologic changes over time in cat epithelium during continuous wear of orthokeratology lenses.

METHODS

Four 2-year-old female cats were used; one served as a no lens wear control and three wore custom designed Paragon CRT lenses for myopic and hyperopic correction in the right and left eyes, respectively. Lenses were worn continuously and animals were euthanased after 4h, 8h and 14 days. Corneal tissue was fixed then stained with hematoxylin and eosin for histologic evaluation and measurement of epithelial thickness.

RESULTS

Average epithelial thickness of control eyes in the centre (38+/-1 microm) and mid-periphery (3.0 mm from the centre, 38+/-2 microm) of the cornea was similar. Epithelial thickness in myopic corrected eyes showed progressive thinning in the centre and progressive thickening in the mid-periphery with increased lens wearing time. Hyperopic corrected eyes showed the opposite pattern of progressive epithelial thickening in the centre and thinning in the mid-periphery with lens wearing time.

CONCLUSIONS

The epithelium appears to play a major role in the changes induced by orthokeratology lenses. The epithelial effects were dependent on time and lens design. Further studies are needed to determine the mechanisms responsible for these changes.

Good clinical practice in orthokeratology

Overnight orthokeratology is becoming more and more popular especially in the Asia-Pacific region where the treatment is primarily used for myopic control in young children. Risk of complications in contact lens wear increases during overnight wear and may further increase when the treatment is used on children. The aim of this paper is to provide a comprehensive guideline for practitioners to improve their orthokeratology practice and minimize unnecessary or preventable complications. The fundamental requirement for starting an orthokeratology practice is to have proper education in the area and to equip the practice appropriately. Overnight trial fitting is recommended to confirm the physiological response prior to commencement of the treatment. Practitioners should provide adequate information, both oral and written, to patients before and after the commencement of treatment to avoid any legal dilemmas and to improve patients' compliance. Costs for the treatment should be transparent and provision of an emergency contact number is a must. Patients should be regularly recalled for aftercare visits and all communication with patients should be properly documented. In this paper, patient selection and the clinical procedures were discussed and a standard of practice in orthokeratology proposed. We believe that the key to providing a safe orthokeratology practice is to continually update knowledge in the field, and to practice to the highest professional standards.

Orthokeratology-Related Infectious Keratitis: A Case Series

PURPOSE

To describe five patients who developed infectious keratitis after the use of overnight orthokeratology contact lenses.

METHODS

Retrospective case report of five patients with infectious keratitis seen in Singapore National Eye Centre between 2001 and 2006.

RESULTS

Five children between the ages of 9 and 14 years, who wore their lenses for an average of 1.5 months before developing orthokeratology-related infectious keratitis, were seen and treated at the Singapore National Eye Centre. All five patients had cultures that were positive for Pseudomonas aeruginosa. They were treated with fortified cefazolin (50 mg/mL) and gentamicin (14 mg/mL) and responded well, with resolution of the infectious keratitis. Although most patients had a best-corrected visual acuity of 20/40 or better after the resolution of the acute infection, they all showed a central or paracentral residual scar.

CONCLUSIONS

Because of the safety issues involved, orthokeratology should be used with caution in children.

Acanthamoeba keratitis related to orthokeratology

PURPOSE

To report four cases of Acanthamoeba keratitis related to the overnight wearing of orthokeratology lenses.

METHODS

Four patients had histories of overnight wearing of orthokeratology lenses when they presented with corneal ulcers. They had used a contact lens care system irregularly with tap water.

RESULTS

The organism isolated by corneal scraping was Acanthamoeba. The patients were treated with polyhexamethylene biguanide (PHMB) and chlorhexidine, resulting in a resolution of ocular inflammation.

CONCLUSION

The risk of Acanthamoeba keratitis as a potential complication of overnight orthokeratology should be considered, especially in patients with over one-year duration of contact lens wearing. Careful contact lens management is needed and tap-water rinsing should be eliminated from the lens care regimen.

Molecular characterization of Acanthamoeba isolated from amebic keratitis related to orthokeratology lens overnight wear

In an effort to characterize, on the molecular scale, the Acanthamoeba initially isolated from the cornea of an amoebic keratitis patient associated with overnight-wear orthokeratology lens in Korea, we conducted mitochondrial DNA restriction fragment length polymorphism, 18S rDNA sequencing, and drug sensitivity analyses on the isolate (KA/PE1). The patient was treated with polyhexamethylene biguanide, chlorhexidine and oral itraconazole, which resulted in resolution of the patientos ocular inflammation. The majority of the molecular characteristics of the KA/PE1 were determined to be identical, or quite similar, to those of A. castellanii Ma strain, which had been isolated also from amoebic keratitis. The risk of Acanthamoeba keratitis as a potential complication of overnight orthokeratology is briefly discussed.

Central corneal epitheliopathy in a long-term, overnight orthokeratology lens wearer: a case report

PURPOSE

The purpose of this study is to report an unusual case of central corneal epitheliopathy (CCE) in a long-term orthokeratology lens wearer.

CASE REPORT

A single observational case report of a 12-year-old Chinese female myope with 3(1/2) years' experience in wearing orthokeratology lenses overnight was diagnosed with a CCE lesion during her regular orthokeratology aftercare consultation. The patient was asymptomatic. Trace or almost negative fluorescein staining was observed over the particular lesion area and, according to the clinical features of the corneal lesion, was thought to be a partially formed "dellen." The lesion healed after the use of the orthokeratology lenses was suspended for 4 months and reappeared when the patient resumed wearing the lenses. Close monitoring of the corneal condition was needed on this patient, and permanent discontinuation of the orthokeratology procedures will be considered if the signs and symptoms of the lesion worsen.

DISCUSSION

The etiology, clinical management and the possible differential diagnosis of the central cornea "dellen" are discussed.

CONCLUSION

A central corneal "dellen" may be associated with long-term, overnight use of orthokeratology lenses.

Infectious keratitis related to orthokeratology

PURPOSE

To report 28 cases of infectious keratitis related to orthokeratology lens overnight wear in China.

METHODS

From March 2000 to August 2001, 28 cases of infectious keratitis related to overnight orthokeratology lens wear were diagnosed in Beijing Institute of Ophthalmology. These were retrospectively reviewed with regard to the pathogens isolated, duration of wear, the time since onset of symptoms, and age. Cultures of corneal scrapes for bacteria, fungus and Acanthamoeba were performed in all of the 28 cases.

RESULTS

All cases were students, including 10 males and 18 females, average age was 16 years (range 10-21 years). The duration of orthokeratology overnight wearing was from 2 weeks to 2 years. Uncorrected visual acuity (UCVA) on initial examination in our institute was from 20/200 to light perception. Of 28 isolates, 24 were culture positive (including 11 bacteria, 11 Acanthamoeba and two fungi), and four were culture negative. In two of the four culture negative cases, Acanthamoeba cysts were detected in the corneal stroma with the confocal microscope. Acanthamoeba and Pseudomonas aeruginosa accounted for 75% (21 of 28) of the cases of infectious keratitis.

CONCLUSION

Infectious keratitis is a severe complication associated with overnight orthokeratology lens wear. Ophthalmologists should pay more attention to this complication in practice.

Efficacy of multipurpose solutions for rigid gas permeable lenses

The use of multipurpose solutions for cleaning and disinfecting rigid gas permeable lenses has replaced single purpose solutions, but there are no reports of the efficacy of these multipurpose solutions, or of the effects of storage conditions on their disinfecting capacities. This study investigated activity against four bacterial and two fungal species, and the effects of storage in a refrigerator, at room temperature, at elevated temperature in both dry and humid conditions and with exposure to sunlight. The disinfecting solutions were challenged with the micro-organisms initially upon opening and then at 2-weekly intervals up to 12 weeks after being stored under the different conditions. Solutions were opened daily to simulate use. One solution failed to meet Food and Drug Administration (FDA) criteria to reduce numbers of bacteria by three log dilutions and of fungi by one log dilution. Storage reduced activity of all solutions over the 12-week period, but not below the requirements of the FDA. Storage in the refrigerator tended to reduce disinfecting capacity more quickly. Multipurpose solutions for rigid gas permeable (RGP) lenses lose activity over the 3 months recommended time of use but remain satisfactory for use over this time in the conditions tested. Practitioners need to remind patients to replace their solutions regularly and should advise against storage in the refrigerator. Multipurpose solutions for RGP lenses have simplified cleaning and disinfecting processes and the current formulations have improved disinfecting capacity compared to former disinfecting solutions, which is particularly important for wearers of orthokeratology lenses.

Prevention of Bacterial Colonization of Contact Lenses With Covalently Attached Selenium and Effects on the Rabbit Cornea

PURPOSE

Although silicone hydrogel materials have produced many corneal health benefits to patients wearing contact lenses, bacteria that cause acute red eye or corneal ulcers are still a concern. A coating that inhibits bacterial colonization while not adversely affecting the cornea should improve the safety of contact lens wear. A covalent selenium (Se) coating on contact lenses was evaluated for safety using rabbits and prevention of bacterial colonization of the contact lenses in vitro.

METHODS

Contact lenses coated with Se were worn on an extended-wear schedule for up to 2 months by 10 New Zealand White rabbits. Corneal health was evaluated with slit-lamp biomicroscopy, pachymetry, electron microscopy, and histology. Lenses worn by the rabbits were analyzed for protein and lipid deposits. In addition, the ability of Se to block bacterial colonization was tested in vitro by incubating lenses in a Pseudomonas aeruginosa broth followed by scanning electron microscopy of the contact lens surface.

RESULTS

The covalent Se coating decreased bacterial colonization in vitro while not adversely affecting the corneal health of rabbits in vivo. The Se coating produced no noticeable negative effects as observed with slit-lamp biomicroscopy, pachymetry, electron microscopy, and histology. The Se coating did not affect protein or lipid deposition on the contact lenses.

CONCLUSION

The data from this pilot study suggest that a Se coating on contact lenses might reduce acute red eye and bacterial ulceration because of an inhibition of bacterial colonization. In addition, our safety tests suggest that this positive effect can be produced without an adverse effect on corneal health.

Bacteria commonly isolated from keratitis specimens retain antibiotic susceptibility to fluoroquinolones and gentamicin plus cephalothin

PURPOSE

Patients presenting with presumed infective keratitis were studied to determine predisposing factors, the current susceptibilities of the bacterial isolates to a range of relevant antibiotics, the success rate of topical antibiotic treatment of keratitis and predictors of failure of topical therapy.

METHODS

Corneal scrapings taken from patients who presented between January 2002 and December 2003 to the Sydney Eye Hospital Emergency Department with keratitis were cultured. The minimum inhibitory concentration of selected antibiotics was determined for each bacterial isolate using an agar dilution technique.

RESULTS

One hundred and twelve consecutive patients presented with corneal ulcers. Forty-seven of the 112 (42%) patients had a growth from the corneal scraping. Potential predisposing factors were identified in 64% of patients, most frequently contact lens wear (36% of patients). Coagulase-negative staphylococci were the most common species isolated. Other common organisms isolated include Pseudomonas aeruginosa, Corynebacterium spp., Staphylococcus aureus and Streptococcus spp.

CONCLUSIONS

Most microorganisms isolated from patients with bacterial keratitis showed susceptibility to ciprofloxacin and aminoglycosides. Cephalothin plus aminoglycoside constituted an effective initial broad-spectrum antibiotic combination. The success rate of topical antibiotic treatment of corneal abscess is 89%. Predictors of failure include older age group, medium or large ulcer, culture-negative keratitis, hypopyon and poor visual acuity.

Daytime orthokeratology associated with infectious keratitis by multiple gram-negative bacilli: Burkholderia cepacia, Pseudomonas putida, and Pseudomonas aeruginosa

PURPOSE

To report a case of a corneal ulcer in a patient who wore orthokeratology contact lenses during the day.

METHODS

Case report.

RESULTS

A 16-year-old girl who underwent orthokeratology treatment developed a corneal ulcer in her right eye. The refractive status of the affected eye was -5.75 -1.75 x 180, and the best-corrected visual acuity was 20/40. Corneal topography showed the temporal upper dislocation of a central flattened zone in the right eye. The patient had worn orthokeratology contact lenses during the day for more than 4 years. Her ulcer became worse after treatment with tobramycin and gentamicin for 1 day. After treatment with ciprofloxacin, the ulcer healed, and visual acuity returned to 20/20 with spectacle correction. Cultures of the cornea, contact lens, and lens solution all grew Burkholderia cepacia, Pseudomonas putida, and Pseudomonas aeruginosa.

CONCLUSIONS

Improper fitting of lenses and contamination of lenses or solutions in orthokeratology therapy are risk factors for a corneal ulcer, even when patients wear orthokeratology lenses only during the day.

Microbial keratitis in overnight orthokeratology: review of the first 50 cases

PURPOSE

Despite growing evidence for clinical efficacy of orthokeratology (OK) for the temporary reduction of myopic refractive error, there has been an increasing number of reports of microbial keratitis (MK) in association with overnight wear of OK lenses. This article analyzes the first 50 cases of MK reported in overnight OK, in order to define the spectrum of the disease and to identify possible risk factors.

METHODS

All reported cases of presumed MK in overnight OK from 2001 onwards were included in the analysis. Demographic data of patients affected and lenses worn, and details of the disease process and possible risk factors were extracted from these reports.

RESULTS

Most cases of MK in OK were reported from East Asia (80%) and most affected patients were Asian (88%). The peak age range was from 9 to 15 years (61%). Although Pseudomonas aeruginosa was the predominant organism implicated in this series of cases (52%), an alarmingly high frequency of Acanthamoeba infection (30%) was found. Inappropriate lens care procedures, patient noncompliance with practitioner instructions, and persisting in lens wear despite discomfort emerged as potential risk factors.

CONCLUSIONS

The high frequency of MK in overnight OK in young Asian patients is likely to reflect the demographics of the OK lens-wearing population. The high frequency of Acanthamoeba infection strongly suggests that tap water rinsing should be eliminated from the lens care regimen for overnight OK. This study does not reveal the absolute incidence or relative risk of MK in overnight OK, and it is therefore premature to ascribe increased risk to this lens-wearing modality compared with other contact lens modalities.

Infectious keratitis related to overnight orthokeratology

PURPOSE

To report the microbial culture results, clinical course, and visual outcomes for infectious keratitis related to overnight orthokeratology.

METHODS

The records of patients with infectious keratitis related to overnight orthokeratology who presented to a tertiary referral center from April 2000 to March 2003 were retrospectively reviewed.

RESULTS

Twenty patients (21 eyes) were included; 1 patient had bilateral infections. The average age of the patients was 14 years. The average period between the time the patient started the overnight orthokeratology program and the onset of infectious keratitis was 23 months. Thirteen of the 21 eyes were culture positive. Organisms cultured were Pseudomonas aeruginosa (n = 9), coagulase-negative Staphylococcus species (n = 2), Serratia marcescens (n = 1), and Acathamoeba species (n = 1). All patients responded well to medical antimicrobial treatment. Final best spectacle-corrected visual acuity ranged from 20/20 to 20/100.

CONCLUSIONS

Infectious keratitis is a potential complication of overnight orthokeratology that may cause significant visual impairment. Parents of children who consider overnight orthokeratology should evaluate the benefit of temporary myopia reduction and the risk of infection.

Overnight orthokeratology-associated microbial keratitis

PURPOSE

This study was designed to report the clinical aspects, microbiologic findings, and treatment outcomes of overnight orthokeratology-associated microbial keratitis.

METHODS

Medical records of patients with overnight orthokeratology-associated microbial keratitis at National Taiwan University Hospital from August 2000 to October 2001were reviewed. The clinical and microbiologic characteristics and treatment outcomes were investigated.

RESULTS

Nine patients (in total 10 eyes) from aged 8 to 17 (mean, 12.3 +/- 2.9) years were included in this study. Eight patients had a unilateral infection and one had a bilateral infection. The initial best corrected visual acuities ranged from hand motion to 20/20. The lesions were located at the central cornea in nine eyes (90%). Smears and cultures from corneal scrapings were obtained from all patients. Four eyes were culture-positive, which included nonfermentative Gram-negative bacillus, Pseudomonas aeruginosa and Acanthamoeba. Positive smears from another two eyes revealed Gram-negative bacilli and double-walled cyst. All patients were cured using antimicrobial medications with complete re-epithelization and disappearance of corneal infiltrates. Four eyes had a final best corrected visual acuity of 20/30 or worse after a mean follow-up of 9.4 months, including one eye that had visual acuity of hand motion only. Complications included corneal opacity in all eyes, glaucoma in one eye, and cataract in one eye.

CONCLUSIONS

Overnight orthokeratology is an important risk factor of microbial keratitis, especially in school children. Acanthamoeba and Gram-negative bacilli, especially Pseudomonas aeruginosa, are the most common pathogens in our series. The risk of microbial keratitis after overnight orthokeratology should not be overlooked.

Acanthamoeba keratitis during orthokeratology

PURPOSE

To report an infectious complication of overnight rigid gas-permeable contact lenses.

METHODS

Case report and medical literature review.

RESULTS

A 16-year-old girl developed laboratory-confirmed acanthamoebic keratitis during orthokeratology for myopic reduction. Recent case reports suggest that Acanthamoeba is a cause of microbial keratitis associated with gas-permeable contact lenses among teenagers and young adults undergoing orthokeratology.

CONCLUSIONS

Acanthamoeba keratitis is an emerging complication of orthokeratology in young myopes.

Serratia Corneal Ulcers

PURPOSE

To study the clinical and microbiological profile of Serratia corneal ulcers at the Cornea Service of the Wills Eye Hospital.

METHODS

This was a retrospective, observational case series. The clinical records of patients with Serratia marcescens corneal ulcers seen at the Cornea Service of the Wills Eye Hospital between January 1, 1998 and December 31, 2002 were reviewed.

RESULTS

Twenty-four cases of Serratia keratitis were identified in 21 patients. Two patients (9.5%) had recurrent keratitis, 1 of which recurred twice. Both had corneal graft edema and were on topical steroids and antiglaucoma drops. The Serratia infection in 15 patients (71%) was associated with an abnormal corneal surface. Twelve of these patients (57%) had the ulcer in a corneal graft, 4 (19%) of which were associated with suture infiltrates. Fifteen patients (71%) were on topical medications-15 used corticosteroids and 13 used antiglaucoma drops. Six patients (29%) were contact lens wearers-1 had a concomitant suture infiltrate associated with a corneal graft, and 5 had otherwise healthy corneas. One isolate lacked in vitro susceptibility to ciprofloxacin and ofloxacin but was susceptible to gentamicin and tobramycin. Nineteen patients had a favorable response to medical therapy. Two patients with poor outcome had large corneal ulcers with severe necrosis and thinning associated with delay in treatment.

CONCLUSIONS

Serratia marcescens keratitis is associated with the presence of an abnormal corneal surface, use of topical medications, and contact lens wear. Prompt medical therapy results in a good clinical response in the majority of cases.

Infectious Keratitis After Overnight Orthokeratology in Canada

PURPOSE

To report 3 cases of infectious keratitis related to overnight orthokeratology use.

METHODS

Retrospective case observation.

RESULTS

All 3 patients were using overnight orthokeratology lenses when they presented with unilateral corneal ulcers. The organisms isolated were Acanthamoeba, Pseudomonas aeruginosa, and Serratia marcescens. The clinical presentation and treatment of each case is presented.

CONCLUSIONS

Overnight orthokeratology use may be associated with infectious keratitis despite the use of more oxygen-permeable materials and improved lens design. Patient education with informed consent, appropriate lens care, and meticulous follow-up is important. Because this complication is potentially sight threatening, orthokeratology requires further analysis and evaluation to establish its safety. The cases here are the first few reported cases in North America.

Characteristics of Pseudomonas corneal infection related to orthokeratology

PURPOSE

To describe a Pseudomonas aeruginosa corneal infection resulting from orthokeratology.

METHODS

Case report.

RESULTS

A 17-year-old boy wearing orthokeratology (OK) lenses was referred to our clinic because of redness in his right eye in spite of his usage of ofloxacin (OFLX) eye drops. An excavated paracentral corneal ulcer with an immune ring and hypopyon was observed. It was positioned under the paracentral steeper portion of the optic of the OK lens. Culture of the lens solution revealed P. aeruginosa. The patient was treated with topical OFLX and cefmenoxime (CMX) plus intravenous and subconjunctival injections of cefozopran (CZOP), successfully. The antibiotic susceptibility of P. aeruginosa by the disk diffusion susceptibility test was reduced under moderately hypoxic conditions. Glycocalyx slime was formed on the OK lens in vitro by P. aeruginosa isolated from the case.

CONCLUSIONS

Changes in P. aeruginosa susceptibility to antibiotics under moderately hypoxic conditions and glycocalyx slime formation might affect the features of OK lens-associated infections.

Microbial flora of tears of orthokeratology patients, and microbial contamination of contact lenses and contact lens accessories

PURPOSE

The purpose of this study is to determine if there are changes in the ocular flora of overnight orthokeratology (ortho-k) patients, and the levels of contamination of their lenses and lens accessories, and to correlate compliance with levels of contamination.

METHOD

Normal ocular flora of 41 subjects was determined twice before commencing ortho-k lens wear by culture of the lower conjunctiva. Further specimens were collected on six follow-up visits after beginning lens wear, as were samples from their lenses, cases, and suction holders. A questionnaire on lens care was administered after the fifth visit.

RESULTS

Three subjects provided conjunctival samples yielding Staphylococcus aureus on one occasion before lens wear, one being positive for this organism after beginning lens wear. Of 38 subjects yielding no growth or only normal eye flora before use, 28 remained free of ocular pathogens after beginning lens wear. Only four subjects had positive cultures on more than one occasion after lens wear. There was no significant difference in isolation levels of pathogens with lens wear (p = 0.423). Lens culture of 54% of subjects yielded no growth or normal flora only; lenses of 16 subjects yielded potential pathogens, including three subjects contaminated on more than one occasion. Lens isolates did not match the organisms transiently colonizing the eye. Lens case, the most frequently contaminated item, was associated with lens contamination (p < 0.001), the same organism being isolated from both items in 11 subjects. Lens suction holder was less frequently contaminated. Neither lens case nor suction holder contamination was associated with isolates from the eye. Reported good compliance correlated with lack of contamination in all but one subject. The most frequent breaches in the lens care protocol were failure to clean, disinfect, and replace the lens case.

CONCLUSION

Ocular flora was not altered by ortho-k lens wear over an extended period, and patients remained free of infection. Contaminants identified were generally of a transient nature. Most patients had significant contamination of at least one item, most frequently the lens case. Lens case isolates were significantly associated with those from the lens. The majority of patients reporting good compliance had low or no contamination of their lenses and accessories.

The Current State of Corneal Reshaping

PURPOSE

The application of contact lenses to alter the shape of the cornea and temporarily reduce or eliminate myopia is known as orthokeratology, corneal refractive therapy, or corneal reshaping. It was first introduced in the 1960s, but high oxygen permeable materials and more sophisticated designs allow patients to wear contact lenses only during sleep, while dramatically improving the predictability and rate of myopia reduction. Many studies have shown that most corneal reshaping patients achieve uncorrected visual acuity of 20/25 or better that lasts all day long in one to two weeks of nighttime wear. Treatment is primarily effective through central epithelial thinning and midperipheral epithelial and stromal thickening. Much remains to be learned about corneal reshaping contact lenses and their effects on the cornea.

METHODS

The authors reviewed existing knowledge and determined what needs to be learned in order to provide patients with appropriate informed consent prior to corneal reshaping contact lens wear.

RESULTS

While corneal reshaping contact lenses are effective at temporarily reducing or eliminating myopia, claims about the progress of myopia being controlled with corneal reshaping contact lenses should not be made until further studies are published in peer-reviewed literature. The incidence and prevalence of microbial keratitis related to corneal reshaping contact lens wear is not known. Any overnight wear of contact lenses increases the risk of infection, but it is not known whether the risks of microbial keratitis are greater for corneal reshaping overnight contact lens wearers than other form of overnight contact lens wear. It is also not known whether the risk of microbial keratitis is greater for children than adults, but we must determine if children are at greater risk than adults because many children are wearing corneal reshaping contact lenses.

CONCLUSIONS

Finally, it is recommended that ongoing education be provided to practitioners and staff regarding safety, informed consent, and prevention of potential problems, with special emphasis on the critical need to properly and thoroughly disinfect lenses that will be worn overnight.

Change of Proliferation Rate of Corneal Epithelium in the Rabbit with Orthokeratology Lens

OBJECTIVE

To investigate the cell proliferation rate of normal corneal epithelium with extended orthokeratology lens (OKL) wear in comparison with extended rigid gas-permeable (RGP) lens wear.

METHODS

Twenty-four rabbits were fitted unilaterally with either an OKL or an RGP lens, and the other eye was used as a control. They were injected with 5-bromo-2-deoxyuridine (BrdU) 24 h prior to being sacrificed. The rabbits were sacrificed at 1, 3, 7 and 14 days after lens fitting. The cornea from the superior limbus to the center was taken at 1.0-mm intervals. The BrdU-labeled cells were counted in medium power fields (x200) in each sample using light microscopy.

RESULTS

The number of BrdU-labeled cells in the RGP lens group initially increased, but the number decreased in the corneal center and superior limbus by 32 and 8%, respectively, after 14 days. There was no statistically significant change. However, the number of BrdU-labeled cells in the OKL group decreased after 3 days, and the number of BrdU-labeled cells was reduced in the center and superior limbus by 63 and 8%, respectively, after 14 days. The change in proliferation in the corneal center in the OKL-wearing rabbits was statistically significant compared to the control (p < 0.05).

CONCLUSIONS

Wearing an OKL had a greater effect on the change of the proliferation pattern in the epithelium than wearing an RGP lens, which suggests that the OKL might be less physiologic than the RGP lens is.

Role of bacterial proteases in pseudomonal and serratial keratitis

Pseudomonas aeruginosa and Serratia marcescens can cause refractory keratitis resulting in corneal perforation and blindness. These bacteria produce various kinds of proteases. In addition to pseudomonal elastase (LasB) and alkaline protease, LasA protease and protease IV have recently been found to be more important virulence factors of P. aeruginosa . S. marcescens produces a cysteine protease in addition to metalloproteases. These bacterial proteases have a number of biological activities, such as degradation of tissue constituents and host defense-oriented proteins, as well as activation of zymogens (Hageman factor, prekallikrein and pro-matrix metalloproteinases) through limited proteolysis. In this article, the properties of these bacterial proteases are reviewed and the pathogenic roles of these proteases in pseudomonal keratitis are discussed.

Corneal ulcers in two children wearing paragon corneal refractive therapy lenses

OBJECTIVES

To report the development of corneal ulcers in two children wearing Paragon Corneal Refractive Therapy (CRT) lenses.

METHODS

Two case reports of children who developed corneal ulcers when fit with Paragon CRT contact lenses, which were worn nightly, are discussed. Each patient presented with a bacterial corneal ulcer after wearing CRT contact lenses for less than 6 months. In the first patient, Pseudomonas aeruginosa was identified as the causative organism. In the second patient, Haemophilus influenza was cultured from the ulcer.

RESULTS

Both patients were treated with intensive, fortified antibiotics with rapid resolution of the corneal ulcers and preservation of vision. No surgical intervention was required.

CONCLUSIONS

Paragon CRT lenses have been approved for use in patients of all ages. When used in children, these lenses may present unique problems. The absolute incidence of bacterial corneal ulcers in patients with CRT lenses are unknown. Severe caution should be used before prescribing CRT lenses for children and informed consent should include potential sight-threatening corneal ulcers.

Pseudomonas aeruginosa corneal binding after 24-hour orthokeratology lens wear

PURPOSE

To examine the effect of short-term 24-hr orthokeratology lens (OKL) wear on Pseudomonas aeruginosa binding, epithelial surface cell morphology, epithelial sheet thickness, and stromal thickness in a rabbit model.

METHODS

Seventeen New Zealand white rabbits were treated according to the Association for Research in Vision and Ophthalmology Statement for the Use of Animals in Ophthalmic and Vision Research. Partial membranectomy was performed on all rabbits 1 week before the experiments. Baseline values for epithelial and stromal thickness and epithelial surface cell size were determined by in vivo confocal microscopy in one randomly chosen eye (n = 6). One week later, rabbits were fitted in the same eye with a hyper oxygen-transmissible OKL. Twenty-four hours later, confocal microscopy was repeated. The second group of rabbits (n = 6) was fitted with an OKL in one randomly chosen eye for 24 hr. P. aeruginosa binding to the corneal epithelium was assessed for the control corneas and those exposed to the test lens. Scanning electron microscopy was performed on a third group of rabbits to assess epithelial surface damage (n = 5).

RESULTS

There was a statistically significant difference (P<0.001) in P. aeruginosa binding between the control (1.11 +/- 0.74 x 10(5) colony-forming units per cornea) and the OKL-wearing eyes (2.74 +/- 0.69 x 10(5) colony-forming units per cornea). The central epithelium thinned by 6.5% after lens wear (48.2 +/- 1.9 microm to 45 +/- 1.7 microm, P=0.005); however, central stromal thickness increased by 7.3% (322 +/- 22 microm to 345 +/- 29 microm, P=0.006). Compared with the baseline value, central epithelial cell size increased significantly from 1,253 +/- 140 mm(2) to 1,627 +/- 393 mm(2) (29.4%, P=0.02). Scanning electron microscopy showed increased surface epithelial damage associated with OKL wear.

CONCLUSIONS

This prospective, masked, pilot study showed that 24-hr hyper oxygen-transmissible OKL wear induced a statistically significant increase in P. aeruginosa binding to the epithelium of the rabbit cornea, accompanied by central epithelial thinning, stromal thickening, and surface cell damage assessed by scanning electron microscopy. Collectively, the data suggest that despite adequate lens oxygen transmissibility, the mechanical pressure inherent in the OKL design exerted on the corneal surface appears to be associated with increased adherence of P. aeruginosa to surface corneal epithelial cells, which may pose an increased risk for lens-related microbial keratitis, especially in overnight (i.e., closed-eye) wearing conditions. Future studies are needed to determine whether these results are similar in human wear and how P. aeruginosa binding during OKL wear compares with other lens-wearing modalities, such as daily or continuous soft lens wear.

Is Corneal Refractive Therapy a New Modality Whose Time Has Come or Repackaged Orthokeratology Whose Time Has Passed?

I was asked to evaluate corneal refractive therapy (CRT) as an experienced ophthalmologist, who is a corneal specialist. I reviewed the literature and listened to and talked with ophthalmologists, optometrists, and researchers using and studying CRT. I feel that CRT is safe and effective. It offers a nonsurgical option for patients who are not eligible for surgery, particularly because of age, or for those who want to correct myopia for daytime vision but do not want to have surgery or wear a contact lens. CRT can be a valuable option to provide patients in a refractive surgery practice.

Adverse Corneal Events Associated With Corneal Reshaping

PURPOSE

This case series presents the first documented cases of infectious ulcers associated with overnight orthokeratology in North America and other less serious complications associated with overnight corneal reshaping.

CASE REPORTS

Five cases of adverse corneal events associated with corneal refractive therapy are described: two cases of microbial keratitis, one case of infiltrates, one case of toxic keratitis, and one corneal abrasion.

CONCLUSIONS

Corneal compromise and poor compliance can cause adverse events with corneal reshaping. The need for ongoing patient education is important not only for pediatric contact lens patients, but also for adults.

Acanthamoeba keratitis as a complication of orthokeratology

PURPOSE

To present four cases of Acanthamoeba keratitis as a complication of orthokeratology.

DESIGN

Observational case report.

METHODS

Four patients with Acanthamoeba keratitis had histories of overnight orthokeratology lens wear of 6 months to 2 years.

RESULTS

Three cases were diagnosed with Acanthamoeba keratitis by corneal scraping and one by confocal microscopy examination. The patients were treated with chlorhexidine, metronidazole, and neomycin sulfate, resulting in a rapid resolution of ocular inflammation.

CONCLUSION

Overnight wear of orthokeratology lenses may induce Acanthamoeba keratitis.

Comparison of Reverse-Geometry Lens Designs for Overnight Orthokeratology

PURPOSE

The efficacy of overnight wear of four types of reverse-geometry lenses was compared. The length of time needed to achieve correction and any adverse events that occurred during the course of the study were recorded.

METHODS

In this prospective, randomized study, 60 subjects (18 to 35 years old) with refractive error between -1.00 to -4.00 D (cyl </= -1.50) wore reverse-geometry lenses overnight only. All subjects were assigned a Rinehart Reeves lens in one eye, and subsets of 20 subjects were randomly assigned a Mountford BE, DreimLens, or Contex D Series 4 lens for the contralateral eye. Visits included baseline, dispensing, 1 day, 1 week, and 1 month. Biomicroscopy, unaided visual acuity, subjective refraction, best-corrected visual acuity at high and low contrast and high and low illumination, corneal topography, and subjective rating data were collected.

RESULTS

Forty-six subjects completed the study. At 1 month, there were no significant differences between lens types in their effect on unaided visual acuity, subjective sphere, subjective cylinder, best-corrected visual acuity at high and low contrast at high illumination and low contrast at low illumination, apical corneal radius, corneal eccentricity, and subjective ratings. Between 1 week and 1 month, there was a significant improvement in subjective ratings of quality of day and night vision (p < 0.05) but no significant change in the objective measures. No significant ocular adverse events were observed during the trial.

CONCLUSIONS

The lens types tested were all similarly effective in the reduction of myopic refractive error. Subjective ratings continued to improve after objective measures stabilized at 1 week. Overnight lens wear proceeded for 1 month without significant adverse reactions.

Unusual morphology in orthokeratology contact lens-related cornea ulcer

PURPOSE

To report a case of unusual ulcer morphology in orthokeratology-related corneal ulcer.

METHODS

A single observational case report of a 14-year-old Chinese female myope with a 1.5-month experience wearing overnight B.E. orthokeratology (Capricornia) lenses and presenting with a right stellate-shaped central cornea abscess. Cornea scrapings for Gram stains, culture, and antibiotic sensitivity were performed. The patient was prescribed hourly fortified cefazolin and gentamicin drops.

RESULTS

Pseudomonas aeruginosa grew on blood and chocolate agar cultures. The ulcer was successfully treated with antibiotics and reepithelialized over 5 days. There was a residual central corneal scar. The refraction changed from -4.25 sphere OD and -1.75 -1.75 x160 OS to -3.50 -1.50 x160 OD and -1.50 -1.75 x165, giving a visual acuity of 20/ 25 OD and 20/20 OS.

CONCLUSIONS

A flatter fit of orthokeratology lenses may be associated with unusual cornea ulcer morphology.

Orthokeratology lens-related Pseudomonas aeruginosa infectious keratitis

PURPOSE

To report a case of orthokeratology lens-related Pseudomonas corneal ulcer in an adult.

METHODS

Case report.

RESULTS

A 37-year-old man presented with a 1-day history of painful red eye. He was a soft contact lens wearer before he started on nocturnal orthokeratology lens wear of 8 to 10 hours per night 9 months ago. Corneal scraping sent for culture revealed a heavy growth of Pseudomonas aeruginosa. The patient was treated with intensive topical fortified tobramycin and ceftazidime drops. The ulcer healed with a residual paraxial corneal scar. Although his best-corrected visual acuity (BCVA) recovered from finger counting (8/200) at presentation to 20/30, he suffered visual loss from a premorbid BSCVA of 20/15. His contrast sensitivity (Vector Vision CSV 1000 test) performance was also worse than his fellow eye.

CONCLUSION

Nocturnal orthokeratology lens wear may be associated with an increased risk of infection.

Pseudomonas corneal ulcer related to overnight orthokeratology

PURPOSE

To report two cases of Pseudomonas aeruginosa corneal ulcers as a complication of overnight orthokeratology lens wear.

METHODS

Case report.

RESULTS

Two 11-year-old girls with acute central corneal ulcers were referred to our hospital. In both cases, the ulcers were about 2 mm in diameter, located centrally, contained dense cellular infiltration, and discharged purulent material. Intensive topical ceftazidime was applied to treat the ulcers. Cultures of the scraped corneal tissues and the contact lens storage solutions in both cases grew P. aeruginosa, which was sensitive to the antibiotic. The presenting best-corrected visual acuity was hand motion at 20 cm in one patient and 6/20 in the other. Both patients had received several months of overnight orthokeratology treatment with rigid gas permeable contact lenses to correct myopia (-4.25 D and -4.75 D in the two affected eyes). The final best-corrected visual acuity was 6/60 in one patient and 6/7.5 in the other.

CONCLUSIONS

Overnight orthokeratology contact lens wear carries a potential risk of corneal ulcer and may cause significant visual impairment in children.

Overnight orthokeratology: preliminary results of the Lenses and Overnight Orthokeratology (LOOK) study

BACKGROUND

The Lenses and Overnight Orthokeratology (LOOK) study is a pilot study designed to learn the procedures of orthokeratology lens fitting in preparation for a planned larger clinical trial and to obtain data with which to calculate a sample size for that larger study. Data are presented for the first 3 months of the LOOK study.

METHODS

Sixty subjects were enrolled in this multicenter pilot study to evaluate the success and safety of treatment with overnight orthokeratology contact lenses. Refractive error, corneal topography, and biomicroscopic data were collected to determine the amount of refractive error change achieved, corneal changes, and a safety profile of overnight wear of reverse geometry rigid gas permeable lenses for orthokeratology.

RESULTS

Of the 60 subjects enrolled, 46 completed the 1-month visit, and 31 completed the 3-month visit. The mean change in spherical equivalent manifest refraction from baseline to the morning 3-month visit was 2.08 +/- 1.11 D in the right eye and 2.16 +/- 1.05 D in the left eye. At the 3-month morning visit, 74% of right eyes and 61 % of left eyes had 20/20 unaided visual acuity. No corneal infiltrates or ulcers were noted in any subjects. Observations of fluorescein staining of the cornea, imprinting, and microcysts were noted in some patients at the 3-month visit.

CONCLUSIONS

The preliminary results of the LOOK study indicate that improvement in unaided visual acuity can be attained for at least 6 h after lens removal. The short-term safety and efficacy of the procedure appear to be favorable; however, future studies are needed to determine the long-term outcomes of treatment.