Corneal cross-linking for Acanthamoeba keratitis in an orthokeratology patient after swimming in contaminated water

A bibliometric and citation network analysis of crosslinking

Purpose: Research on crosslinking has focused mainly on trying to slow the progression of keratoconus. The objective of this bibliometric analysis is to determine the relationships between the different publications and authors. As well as to identify the different areas of research on crosslinking. Methods: Web of Science (WOS) was the database for the search of publications for the period 1972 to December 2023, using the terms: crosslinking, cross-linking, ocular, vision, visual, cornea, ectasia AND Keratoconus. The analysis of the publication was performed using the CitNetExplorer, VOSviewer and CiteSpace software. Results: 7161 publications and 59415 citation networks were found. The year with the most publications is 2021, a total of 571 (7.97%) publications and 135 citation networks. The most cited publication was "Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus" published by Wollensak et al. in 2003, with a citation index of 1780. Using the Clustering function, five groups were found that cover the main research areas in this field: keratoconus, corneal transplantation, cataracts, corneal inflammation and axial growth. Conclusion: The treatment of keratoconus continues to be the topic of interest in this area of research. However, in recent years there has been an increase in research on how crosslinking helps to slow down axial growth.

Clinical Features and Visual Outcome of Infectious Keratitis Associated with Orthokeratology Lens in Korean Pediatric Patients

PURPOSE

To investigate the clinical features and visual outcome of infectious keratitis associated with orthokeratology (Ortho-K) lens in Korean pediatric patients.

METHODS

We retrospectively reviewed medical records of patients diagnosed with Ortho-K lens-related infectious keratitis from June 2005 to April 2020 at a tertiary referral hospital. Patients' demographics, clinical features, microbiological evaluation, and treatment methods were assessed, and factors related to final visual outcomes were analyzed.

RESULTS

The study included 26 eyes from 26 patients (19 female and 7 male patients; mean age, 11.9 years), with an average Ortho-K lens wear duration of 33.7 ± 21.2 months. The highest number of cases occurred in summer (11 of 26 cases, 42.3%). Central or paracentral corneal lesions were observed in 25 cases (96.2%), with a mean corneal epithelial defect size of 5.13 mm2. Pseudomonas aeruginosa was the most commonly isolated organism (n = 5), followed by Serratia marcescens (n = 4). All patients responded to medical treatment without needing surgical intervention. 72% of cases achieved favorable visual outcomes (Snellen best-corrected visual acuity [BCVA] >6 / 12), while 8% experienced severe visual impairment (Snellen BCVA ≤6 / 60) due to residual central corneal opacities. Multivariable analysis showed that non-summer seasons (p = 0.043), duration from symptom onset to presentation (p = 0.040), and corneal epithelial defect size (p = 0.002) were significantly associated with final logarithm of the minimum angle of resolution BCVA. Failed autorefraction at presentation due to an Ortho-K-related infectious keratitis lesion was a significant predictor of poor final visual outcome (Snellen BCVA ≤6 / 12; odds ratio, 38.995; p = 0.030).

CONCLUSIONS

Ortho-K lens-related infectious keratitis can lead to permanent corneal opacities and potentially devastating visual outcomes in children. Delayed time to presentation, large corneal lesions, failure of autorefraction, and non-summer seasons were associated with poorer outcomes. Proper education and early detection would be key to safe use of orthokeratology lenses in pediatric patients.

Collagen cross-linking beyond corneal ectasia: A comprehensive review

The history of corneal cross-linking (CXL) dates back to 2003 when some German scientists investigated possible treatments to harden the corneal structure to increase its resistance in ectatic corneal diseases. Nowadays, CXL is considered the most effective therapy in ectatic corneal diseases due to its proven efficacy in hardening the cornea, thus halting the development of the disease. Since 2003, CXL applications have dramatically expanded and have been implemented in several other areas such as infectious keratitis, corneal edema, and before performing keratoplasty for various purposes. Moreover, several irradiation patterns are being studied to correct refractive errors, taking into account the corneal refractive changes that occur after the procedure. Currently, scleral cross-linking is also being investigated as a potential therapy in cases of progressive myopia and glaucoma. In this article, we provide a comprehensive overview of the available applications of cross-linking in nonectatic ocular conditions and highlight the possible future indications of this procedure.

Use of corneal cross-linking beyond keratoconus: a systemic literature review

PURPOSE

The success of corneal collagen cross-linking in altering keratoconus' clinical course has driven a search for further uses of this procedure. This literature review aims to analyze the scientific evidence available for the benefit of cross-linking in the management of ophthalmic diseases other than progressive keratoconus or ectasia induced by corneal refractive procedures.

METHODS

A systemic literature review.

RESULTS

We reviewed 97 studies. We found that collagen cross-linking can limit the progression of several other corneal ectasias, thus reducing and limiting the need for keratoplasty. Collagen cross-linking also can reduce the refractive power of the cornea and can be considered for a moderate degree of bacterial keratitis or when the organism is unidentified, which is refractive to antibiotics alone. However, the comparative rarity of these procedures has limited the extent of evidence. In fungal, Acanthamoeba, and herpes virus keratitis, the evidence is inconclusive of the safety and efficacy of cross-linking.

CONCLUSION

Current clinical data is limited, and laboratory data has not fully correlated with published clinical data.

Surgical management of infectious keratitis

The successful management of infectious keratitis is usually achieved with a combination of tools for accurate diagnosis and targeted timely antimicrobial therapy. An armamentarium of surgical interventions is available in the acute stage which can be resorted to in a step wise manner or in combination guided by the response to treatment. Simple surgical modalities can facilitate accurate diagnosis e.g. corneal biopsy and alcohol delamination. Surgery to promote epithelial healing can vary from tarsorrhaphy, amniotic membrane transplantation or conjunctival flaps depending on the extent of infection, visual prognosis, availability of tissue and surgeon's experience. Collagen crosslinking has been increasingly utilized with successful results to strengthen the cornea and reduce the infective load consequently the need for further elaborate surgical interventions. It has shown encouraging results specially in superficial bacterial and fungal keratitis but for deeper infections, viral and acanthamoeba keratitis, its use remains questionable. When globe integrity is compromised, corneal gluing is the most commonly used procedure to seal small perforations. In larger perforations/fulminant infections a tectonic/therapeutic graft is advisable. Partial thickness grafts are increasingly popular to treat superficial infection or internally tamponade perforations. Peripheral therapeutic grafts face challenges with potential requirement for a manually fashioned graft, and increased risk of rejection due to proximity to the limbal vessels. Late stage visual rehabilitation is likely to require further surgical interventions after complete resolution of infection and inflammation. A preliminary assessment of corneal sensation and integrity of the ocular surface are key for any successful surgical intervention to restore vision.

Irrigation suitability, health risk assessment and source apportionment of heavy metals in surface water used for irrigation near marble industry in Malakand, Pakistan

Water is a vital, finite resource whose quantity and quality are deteriorating as the world population increases. The current study aims to investigate the concentration of heavy metals (HM) in surface water for irrigation purposes with associated human health risks and pollution sources near the marble industry in Malakand, Pakistan. Twenty-seven water samples were randomly collected and analyzed for HM concentration by inductively coupled plasma‒optical emission spectrometry (ICP‒OES). pH, electrical conductivity (EC), total dissolved solids (TDS), biological oxygen demand (BOD), and chemical oxygen demand (COD) were measured using standard methods of American Public Health Association (APHA). Irrigation suitability was assessed using specific water quality parameters. The associated health risks from ingestion and dermal exposure to heavy metals were calculated by USEPA health risk indices. Pollution sources and spatial distribution mapping were studied using compositional data analysis (CoDa) and the application of a geographic information system (GIS) to understand the changing behavior of heavy metals in surface waters. The concentrations of BOD (89%), COD (89%), Al (89%), Ca (89%), Cr (56%), Cu (78%), Fe (56%), K (34%) Mg (23%), Mn (56%), Na (89%), Ni (56%), P (89%), and Zn (11%) exceeded the safety limits of National Environmental Quality standards (NEQs) of Pakistan. The results of Kelly's ratio (KR) classified surface water as unsuitable for irrigation. The average daily doses (ADD, mg/kg/day) for Al, Cu, Cr, Fe, Mn, Ni, and Zn were higher in children than in adults. The hazard index (HI) for children and adults was above the threshold (HI > 1), indicating a significant risk of non-carcinogenic toxicity. The carcinogenic risk values for Cr and Ni were above the USEPA limit (1 × 10-6 to 1 × 10-4), suggesting a potential carcinogenic risk for the target population. Principal component analysis (PCA), biplot (CLR), and the CoDa-dendrogram allowed for the identification of elemental associations, and their potential source was anthropogenic rather than natural in origin. Regular monitoring and phytoremediation strategies are proposed to safeguard crops and human health.

Photoactivated Chromophore Corneal Collagen Cross-Linking for Infectious Keratitis (PACK-CXL)-A Comprehensive Review of Diagnostic and Prognostic Factors Involved in Therapeutic Indications and Contraindications

Infectious keratitis is a severe infection of the eye, which requires urgent care in order to prevent permanent complications. Typical cases are usually diagnosed clinically, whereas severe cases also require additional tools, such as direct microscopy, corneal cultures, molecular techniques, or ophthalmic imaging. The initial treatment is empirical, based on the suspected etiology, and is later adjusted as needed. It ranges from topical administration of active substances to oral drugs, or to complex surgeries in advanced situations. A novel alternative is represented by Photoactivated Chromophore Corneal Collagen Cross-Linking (PACK-CXL), which is widely known as a minimally invasive therapy for corneal degenerations. The purpose of this review is to identify the main diagnostic and prognostic factors which further outline the indications and contraindications of PACK-CXL in infectious keratitis. Given the predominantly positive outcomes in the medical literature, we ponder whether this is a promising treatment modality, which should be further evaluated in a systematic, evidence-based manner in order to develop a clear treatment protocol for successful future results, especially in carefully selected cases.

Overnight orthokeratology-associated Acanthamoeba keratitis at a tertiary referral hospital in Taiwan: A retrospective case-control study

BACKGROUND

Acanthamoeba keratitis (AK) is a vision-threatening disease, usually associated with contact lens (CL) wear. As overnight orthokeratology (OOK) is increasingly used to control myopia, we have found incidence of OOK-associated AK is increasing. This study aimed to investigate the clinical presentation and visual outcomes of OOK-associated AK.

METHODS

Demographic characteristics, clinical features, and treatment outcomes were collected by reviewing the medical charts of CL-associated AK patients (n = 35) diagnosed at Taipei Veterans General Hospital from 2001 to 2016. Cases were OOK-associated AK patients (n = 13), and controls were all other CL-associated AK patients (n = 22). Student t tests and chi-square tests were used to compare cases and controls. Linear regression analyses were used to identify factors associated with the final visual outcome in CL-associated AK.

RESULTS

OOK-associated AK accounted for half of all CL-associated AK after 2010. OOK-associated AK patients and other CL-associated patients had similar best-corrected logarithm of the minimum angle of resolution visual acuity (BCLVA) before treatment (1.10 ± 0.75 vs 1.13 ± 0.76, p = 0.893), but OOK-associated AK patients were younger (17.15 ± 3.21 vs 26.36 ± 12.81 years, p = 0.004), had less severe disease (ring infiltration, 0% vs 31.82%, p = 0.023), and had better post-treatment BCLVA (0.06 ± 0.15 vs 0.51 ± 0.95, p = 0.041). Multiple linear regression analysis showed that better BCLVA after treatment in CL-associated AK was associated with initial presentation without ring infiltration (p = 0.002) but not with OOK use itself (p = 0.793). Twenty-six of 35 CL-associated AK patients had final BCLVA equal to or better than 0.10 (Snellen visual acuity of 6/7.5). All 13 OOK-associated AK cases were treated with chlorhexidine 0.02% ± voriconazole 1% ± oral voriconazole, and 12 of these patients had final BCLVA equal to or better than 0.10.

CONCLUSION

Most CL-associated AK patients had satisfactory visual outcomes. Half of AK at our hospital is OOK-associated since 2010. Early diagnosis and correct treatment may be the reason why OOK-associated AK patients had better vision prognosis.

Safety and efficacy of UV application for superficial infections in humans: A systematic review and meta-analysis

BACKGROUND

Ultraviolet (UV) light is naturally antimicrobial, but risks associated with UV overexposure have limited its clinical application. This systematic review evaluates the safety and efficacy of UV light treatment of superficial human infections.

METHODS

MEDLINE, Embase, Cochrane CENTRAL, ANZCTR and US National Library of Medicine were searched (March 25, 2020). Clinical studies applying UV light (200-400 nm) for superficial infections and non-clinical studies evaluating the antimicrobial effects of UV light on human samples were included. Randomised controlled trials (RCTs) and non- RCTs were appraised using the Cochrane risk of bias and the ROBINS-I tools, respectively.

RESULTS

Eleven RCTs, seven non-RCTs, 24 case studies, and 11 in vitro studies were included. Most clinical studies (34/42) evaluated UVA treatment for microbial keratitis (MK) using cross-linking (UVA-CXL) methods. Six clinical studies assessed UVC; one, UVB; and one, broadband UV for chronic skin infections. Pooled data analysis showed no difference in the time to wound resolution with UVA-CXL relative to standard treatment (mean difference [MD]: -18.20 [95% CI: -39.04 to 2.65] days; p = 0.09). Adverse event incidence was similar to control for UVA-CXL in MK (RR: 0.70 [95%CI: 0.32-1.79]; 5 RCTs) and UVC in skin infections (RR: 0.63 [95%CI: 0.25-1.54]; 2 RCTs).

CONCLUSION

Alone or as an adjunct to standard therapy, UV light shows promise as a safe and effective treatment for a wide range of infections. Applications of UV light as an anti-infective agent are deserving of further evaluation, especially in the context of growing antibiotic resistance.

REGISTRATION

PROSPERO registration number CRD42020176510.

Gas-Permeable Contact Lenses and Water Exposure: Practices and Perceptions

SIGNIFICANCE

This study provides insight into the current recommendations, clinical behaviors, and risk assessments of eye care professionals on the topic of rigid contact lens exposure to tap water. This knowledge may motivate professional organizations to develop initiatives to educate eye care professionals on the dangers of contact lens exposure to water.

PURPOSE

The purpose of this study was to investigate the practice patterns and risk perceptions of eye care professionals regarding gas-permeable contact lens exposure to tap water.

METHODS

A branched-logic survey was started by 320 clinicians, vision scientists, and industry personnel and was fully completed by 272 participants. The survey queried participants about their current practices, recommendations, and perceptions of risk regarding exposure of gas-permeable contact lenses to tap water.

RESULTS

Of those who prescribe gas-permeable contact lenses, 57.4% reported rinsing lenses with tap water, whereas only 32.7% reported engaging in this same behavior in front of patients. Of those who reported never rinsing lenses with tap water, 85.6% indicated that rinsing lenses with water increases infection risk, whereas 52.1% of those who rinse lenses with water reported the same perceived risk (P < .001). Of all participants, 60% indicated that wearing contact lenses while showering increases infection risk, and 50.2% of all participants advised patients to avoid this behavior.

CONCLUSIONS

A discrepancy exists between perceptions of risk concerning exposure of contact lenses to water and both clinical practices and patient education provided by professionals.

Does Orthokeratology Wearing Affect the Tear Quality of Children?

Orthokeratology is currently known as one of the most effective methods of myopia control in the process of rapid deterioration of the global myopia prevalence. As orthokeratology is widely used, it is necessary to evaluate its complications reasonably and accurately. Eye surface problems in children, such as dry eyes, have received increasing attention. At present, there is no conclusive evidence on how orthokeratology affects the ocular surface, especially the tears. To our knowledge, this is the first study to explore the relationship between orthokeratology lenses and tears through meta-analysis. However, it is still challenging to get a convincing conclusion and a higher level of evidence in this meta-analysis. Reasons for this include limitation of study design, lack of clarity on important confounding factors, lack of appropriate statistical tools, and other biases. This paper will analyze the dilemma existing in the current research from different perspectives to provide meaningful information for future studies in this field.

Molecular detection of Acanthamoeba spp. in Seven Crater Lakes of Laguna, Philippines

Acanthamoeba spp. are ubiquitous free-living amoeba with genotypes that cause severe pathology of the eyes, central nervous systems, and rare reports of cutaneous infections. The Seven Crater Lakes are freshwater water resources in Laguna, Philippines primarily used for aquaculture and tourism. A total of 16 surface water samples were collected from different sampling areas per Crater Lake and placed in sterile plastic containers. Samples were filtered using 1.2 μm pore size, glass microfiber filter. Filtered sediments were placed on non-nutrient agar lawned with Escherichia coli and incubated aerobically at 35 °C for 14 days. Six out of 16 water samples exhibited amoebic growth. Cystic stages revealed circular to stellate morphology under light microscopy which were initially classified as Acanthamoeba spp. DNA from positive isolates were made to react with polymerase chain reaction using Acanthamoeba specific primers JDP1 5′-GGCCCAGATCGTTTACCGTGAA-3′ and JDP2 5′-TCTCACAAGCTGCTAGGGAGTCA-3′confirmed the presence of several Acanthamoeba species. Phylogenetic analysis revealed the presence of seven isolates belonging to Acanthamoeba genotypes T4, T5, and T9. The presence of potentially pathogenic Acanthamoeba genotypes in the Seven Crater Lakes of Laguna signifies risk to human health which necessitates the development of programs, policies, and guidelines on the understanding, prevention, and management of potential human infections.

Photoactivated chromophore for infectious keratitis - Corneal cross-linking (PACK-CXL): A systematic review and meta-analysis

PURPOSE

To examine the efficacy of adjuvant photoactivated chromophore for infectious keratitis-corneal cross-linking (PACK-CXL) for the treatment of infectious keratitis (IK).

METHODS

Electronic databases, including MEDLINE, EMBASE and Cochrane Central, were searched for articles related to PACK-CXL. All clinical studies, including randomized controlled trials (RCTs), non-randomized controlled studies, case series and case reports, were included. A meta-analysis was further performed when there were sufficient similarities in the included RCTs. Primary outcome measure was time to complete corneal healing and secondary outcome measures included size of epithelial defect and infiltrate, corrected-distance-visual-acuity (CDVA), and adverse events.

RESULTS

Forty-six eligible studies (including four RCTs) with 435 patients were included. When compared to standard antimicrobial treatment (SAT) alone, adjuvant PACK-CXL resulted in shorter mean time to complete corneal healing (-7.44 days; 95% CI, -10.71 to -4.16) and quicker resolution of the infiltrate at 7 days (-5.49 mm²; 95% CI, -7.44 to -3.54) and at 14-30 days (-5.27 mm²; 95% CI, -9.12 to -1.41). There was no significant difference in the size of epithelial defect, CDVA and risk of adverse events. Evidence on the use of PACK-CXL in acanthamoeba and mixed IK was insufficient.

CONCLUSIONS

Our study demonstrates that adjuvant PACK-CXL expedites the healing of IK when compared to SAT alone (low-quality evidence). Further adequately powered, high-quality RCTs are required to fully ascertain the therapeutic effect of PACK-CXL.

Interstitial keratitis diagnosis and treatment

Interstitial keratitis is a non-ulcerative, non-suppurative, more or less vascularized inflammation of the corneal stroma. The corneal lesions result from the host response to bacterial, viral (40% of cases) or parasitic antigens, or from an autoimmune response (1% of cases) without active corneal infection. The natural history of the disease is divided into two phases: acute and cicatricial. This type of keratitis is less common than ulcerative bacterial keratitis, but it is a non-negligible cause of visual loss. It is associated with systemic or infectious disease and requires early diagnosis and appropriate treatment to optimize visual prognosis and avoid other complications.

Corneal morphology and visual outcomes in LASIK patients after orthokeratology: A pilot study

A STATEMENT OF SIGNIFICANCE

For the first time, this study shows that corneas that previous undergone orthokeratology treatment do not respond differently to LASIK compared with previous soft contact lens wear experience.

PURPOSE

To evaluate and compare the corneal morphology and visual outcomes of long-term soft and orthokeratology (OK) contact lens fitting in wearers undergoing corneal refractive surgery (LASIK) for myopia correction.

METHODS

Sixteen (16) myopic patients wearing hydrophilic soft contact lens (SCL, n = 8 subjects, control group) and OK (n = 8 subjects, OK group) lenses who undergone LASIK were retrospectively evaluated. Preoperative fitting of contact lenses and one year postoperative were studied using Pentacam (Oculus, Inc. GmbH, Wetzlar, Germany). Corneal pachymetry and volume, corneal topography, anterior and posterior surface elevation data and the anterior surface aberrometry of the cornea were recorded and used for fitting.

RESULTS

Age, refractive error and topographic parameters before LASIK did not showed statistically significant differences between the two study groups. LASIK post-treatment results showed identical changes in both control and OK groups and did not show significant differences in all the parameters evaluated. The changes on corneal parameters and HOA due to refractive surgery intervention were not different between Control and OK group (p > 0.050).

CONCLUSIONS

Corneal changes due to OK treatment are reversible after its discontinuation. The present study gives an overview of how OK does not impair future LASIK surgery for the correction of myopia and does not influence the success/results of such intervention. These findings suggest that OK CL wear does not change corneal biomechanics and does not compromise a possible LASIK refractive surgery. Although this is a pilot study and there is a need of evaluate this results/changes in future studies.

A Review of Corneal Collagen Cross-linking - Current Trends in Practice Applications

Objective:

To review the literature on current applications of corneal Collagen Cross-Linking (CXL).

Methods:

A review of publications on corneal cross-linking was conducted. This included systemic reviews, randomized controlled clinical trials, cohort studies, case-controlled studies and case series. A summary of the publications is tabulated.

Results:

The original indication of riboflavin – Ultraviolet-A (UVA) induced corneal collagen cross-linking is to arrest the progression of keratoconus. Studies show that it is effective in arresting the progression of keratoconus and post-LASIK ectasia with the standard Dresden protocol (epithelium-off). There are also improvements in visual, keratometric and topographic measurements over time. Severe complications of cross-linking are rare. The epithelium-on techniques have less efficacy than the Dresden protocol. Accelerated protocols have variable results, with some studies reporting comparable outcomes to the Dresden protocol while other studies reporting less efficacious outcomes. Cross-linking combined with refractive procedures provide better visual outcome but long term studies are warranted. Cross-linking for the treatment of infective keratitis is a promising new treatment modality. Initial studies show that it is more effective for superficial rather than deep infections and for bacterial rather than fungal infections.

Conclusions:

Corneal cross-linking is a procedure with an expanding list of indications from the treatment of corneal ectasias to infective keratitis. While the standard Dresden protocol is established as the gold standard treatment for progressive keratoconus, the more recent protocols may require further refinements, investigative and long-term studies.

Virulent T4 Acanthamoeba causing keratitis in a patient after swimming while wearing contact lenses in Southern Brazil

Several strains of free-living amoebae belonging to the genus Acanthamoeba can cause a painful sight-threatening disease of the cornea known as Acanthamoeba keratitis (AK). The numbers of AK cases keep rising worldwide mainly due to an increase in contact lens wearers and lack of hygiene in the maintenance of contact lenses and their cases. We report a case of AK in a healthy young woman admitted to the Hospital de Clinicas in Porto Alegre, southern Brazil. Corneal scrapings were examined for the presence of Acanthamoeba strains. The initial isolate was characterized by morphological and genotypic properties. The isolate belonged to group III according to Pussard and Pons' cyst morphology. Analysis of its 18S rDNA sequence identified the isolate as genotype T4. The T4 genotype is the most commonly reported among keratitis isolates and the most common in environmental samples.

Water Exposure is a Common Risk Behavior Among Soft and Gas-Permeable Contact Lens Wearers

PURPOSE

To understand soft contact lens (SCL) and gas-permeable (GP) lens wearers' behaviors and knowledge regarding exposure of lenses to water.

METHODS

The Contact Lens Risk Survey (CLRS) and health behavior questions were completed online by a convenience sample of 1056 SCL and 85 GP lens wearers aged 20 to 76 years. Participants were asked about exposing their lenses to water and their understanding of risks associated with these behaviors. Chi-square analyses examined relationships between patient behaviors and perceptions.

RESULTS

GP lens wearers were more likely than SCL wearers to ever rinse or store lenses in water (rinsing: 91% GP, 31% SCL, P < 0.001; storing: 33% GP, 15% SCL P < 0.001). Among SCL wearers, men were more likely to store (24% vs. 13%, P = 0.003) or rinse (41% vs. 29%, P = 0.012) their lenses in water. Showering while wearing lenses was more common in SCL wearers (86%) than GP lens wearers (67%) (P < 0.0001). Swimming while wearing lenses was reported by 62% of SCL wearers and 48% of GP lens wearers (P = 0.027). Wearers who rinsed (SCL; P < 0.0001, GP; P = 0.11) or stored lenses in water (SCL; P < 0.0001, GP P = 0.007) reported that this behavior had little or no effect on their infection risk, compared with those who did not. Both SCL (P < 0.0001) and GP lens wearers (P < 0.0001) perceived that distilled water was safer than tap water for storing or rinsing lenses.

CONCLUSIONS

Despite previously published evidence of Acanthamoeba keratitis' association with water exposure, most SCL, and nearly all GP lens wearers, regularly expose their lenses to water, with many unaware of the risk.

Expert practice patterns and opinions on corneal cross-linking for infectious keratitis

Objective

To assess the current opinion and practice patterns from cornea experts regarding the benefit of corneal cross-linking (CXL) for infectious keratitis (IK).

Methods and analysis

An international survey was distributed to corneal specialists via an internet survey. The survey data collected were analysed with descriptive statistics.

Results

A survey was sent to 190 recipients, and 29 (15%) respondents completed the survey with an average of 7 years’ experience using CXL. A majority of respondents (66%) used CXL to treat IK due to bacterial, fungal, protozoan or unknown aetiology. Main indications to use CXL as adjuvant therapy were worsening infiltrate diameter or depth despite therapy (74%), followed by antibiotic resistance (68%), corneal thinning (53%), poor compliance with medication (26%) and other reasons (21%). Most respondents felt CXL would be at least moderately helpful as an adjuvant therapy for bacterial (96%) or fungal (75%) keratitis; about half (46%) thought it would be helpful for acanthamoeba keratitis. As sole therapy, fewer respondents believed CXL would be at least moderately helpful to treat bacterial (75%), fungal (58%) and acanthamoeba (43%) keratitis.

Conclusion

The survey offered insights into current expert practices and opinions of using CXL as therapy for IK. The results of this survey serve to guide in the design of future clinical studies.

Acanthamoeba in the eye, can the parasite hide even more? Latest developments on the disease

Acanthamoeba spp. is a free living protozoan in the environment, but can cause serious diseases. Acanthamoeba keratitis (AK), a severe and painful eye infection, must be treated as soon as possible to prevent ulceration of the cornea, loss of visual acuity, and eventually blindness or enucleation. Although the disease affects principally contact lens (CLs) wearers, it is recognized nowadays as a cause of keratitis also in non-CLs wearers. Although the number of infections caused by these amoebae is low, AK is an emerging disease presenting an extended number of cases each year worldwide mostly due to the increasing use of CLs, but also to better diagnostic methods and awareness. There are two principal causes that lead to severe outcomes: misdiagnosis or late diagnosis of the causal agent, and lack of a fully effective therapy due to the existence of a highly resistant cyst stage of Acanthamoeba. Recent studies have reported different genotypes that have not been previously associated with this disease. In addition, Acanthamoeba can act as a reservoir for phylogenetically diverse microorganisms. In this regard, recently giant viruses called Pandoravirus have been found within genotypes producing keratitis. What potential risk this poses is not yet known. This review focuses on an overview of the present status and future prospects of this re-emerging pathology, including features of the parasite, epidemiology, clinical aspects, diagnosis, and treatment.

Acanthamoeba keratitis in patients wearing scleral contact lenses

PURPOSE

To report a series of cases of Acanthamoeba keratitis (AK) in scleral lens wearers with keratoconus to determine whether this type of contact lens presents a greater risk for development of infection.

METHODS

This study reports three patients who wore scleral contact lenses to correct keratoconus and developed AK. The diagnoses of AK were established based on cultures of the cornea, scleral contact lenses, and contact lens paraphernalia. This study investigated the risk factors for infections.

RESULTS

The possible risks for AK in scleral contact lens wearers are hypoxic changes in the corneal epithelium because of the large diameter and minimal tear exchange, use of large amounts of saline solution necessary for scleral lens fitting, storing the scleral lens overnight in saline solution rather than contact lens multipurpose solutions, not rubbing the contact lens during cleaning, and the space between the cornea and the back surface of the scleral lens that might serve as a fluid reservoir and environment for Acanthamoeba multiplication. Two patients responded well to medical treatment of AK; one is still being treated.

CONCLUSIONS

The recommendations for use and care of scleral contact lenses should be emphasized, especially regarding use of sterile saline (preferably single use), attention to rubbing the lens during cleaning, cleaning of the plunger, and overnight storage in fresh contact lens multipurpose solutions without topping off the lens solution in the case.

Infectious keratitis and orthokeratology lens use: a systematic review

PURPOSE

Myopia is a prevalent condition among Asians. Orthokeratology lens has gained popularity as a method of myopia control. This systematic review is to summarize the clinical profile of infectious keratitis in association with orthokeratology lens wear.

METHODS

We searched in the PubMed and EMBASE for articles adopting the search strategy "(orthokeratology lens OR orthokeratology) AND (bacterial eye infection OR keratitis OR cornea ulcer OR microbial keratitis OR bacterial keratitis)", from the start date of the databases to August 23, 2016. Articles reporting infectious keratitis in orthokeratology lens users with data of individual cases were considered eligible for this systematic review. We recorded the outcome measures including method of diagnosis, etiological agents, duration and mode of treatment and treatment outcomes.

RESULTS

Our literature search yielded 172 papers. After removing duplicated and irrelevant reports, we included 29 articles for data analysis, involving 173 eyes. Among all reported cases, the mean age at presentation was 15.4 ± 6.2 years, with a female preponderance (male-to-female ratio 1:1.7). Positive microbiological cultures were reported in 69.4% of cases, with Pseudomonas aeruginosa and Acanthamoeba being the most common etiological agents. The mean duration of hospitalization was 7.7 ± 6.7 days. Mean LogMAR visual acuity at presentation was 1.17 ± 0.78, increased to 0.33 ± 0.41 at final visit (p < 0.001).

CONCLUSIONS

Despite early intervention and treatment, the majority of infections resulted in the formation of corneal scars and almost 10% of eyes needed surgical treatment. Timely awareness and treatment of keratitis should be emphasized to the users.

Update on Orthokeratology in Managing Progressive Myopia in Children: Efficacy, Mechanisms, and Concerns

Myopia is an important public health issue, and high myopia may lead to severe complications if left untreated. Orthokeratology lenses, worn overnight to reshape the cornea, are one of many recent modalities used to slow down the progression of myopia in children. This treatment has been proven successful, as evidenced by decreased spherical refractive error and axial length relative to the control at interval follow-up ranging from 6 months to 5 years. In this systematic review, the authors collected published controlled studies that analyzed the efficacy of orthokeratology lens wear and calculated longitudinal relative changes in axial length, revealing a weighted average of -45.1% change in axial length at the 2-year follow-up. The exact mechanism by which orthokeratology lenses reduce myopia progression is unknown, but research shows that the corneal reshaping decreases peripheral hyperopic defocus and therefore increases peripheral myopic defocus to likely reduce stimuli for axial elongation and subsequent development of myopia. Use of orthokeratology lenses is generally safe, but cases of associated infectious keratitis may have a higher incidence of virulent organisms such as Pseudomonas, Acanthamoeba, and antibacterial-resistant strains of Staphylococcus, partially due to the required overnight use of these lenses. Orthokeratology is regarded as one of the most effective non-pharmacologic measures to slow progression of myopia in children and, with regular follow-up to ensure safety, continues to be one of the most effective treatments for myopia management around the world. [J Pediatr Ophthalmol Strabismus. 2017;54(3):142-148.].

Therapeutic and inducing effect of corneal crosslinking on infectious keratitis

The corneal crosslinking (CXL) with riboflavin and ultraviolet-A (UVA) is a new therapy method to successfully treat infectious keratitis in clinical practice. However, there are rare reports on the complications of CXL such as the secondary keratitis. The diverse clinical outcomes on keratitis have highlighted the necessity to further evaluate the efficacy and complications of CXL. We reviewed the positive and negative reports on UVA/riboflavin related with keratitis and provided our opinion on the therapeutic and side effect of UVA/riboflavin crosslinking on keratitis.

Current and Future Applications of Photoactivated Chromophore for Keratitis-Corneal Collagen Cross-Linking (PACK-CXL): An Overview of the Different Treatments Proposed

PURPOSE

To review the application of the PACK-CXL and to identify different treatment protocols according to the pathogens associated with keratitis.

METHODS

A systematic review of 21 articles. The primary outcome was the healing of a corneal ulcer, defined as epithelization, blocking corneal melting. The secondary end-point was the recovery of visual acuity.

RESULTS

We studied a total of 145 eyes. Infectious keratitis was associated with bacteria in 80 eyes (55.55%), fungus in 24 eyes (16.67%), and protozoa in 13 (8.97%). In 26 (18%), the microbiological culture was negative or not performed. The mean time of re-epithelization was 25.70±29.83days (1-180). A total of 27 patients needed corneal transplantation. The overall probability of blocking corneal melting was 84.13%. Three different protocols for each group of pathogens have been proposed.

CONCLUSION

PACK-CXL still has a limit in its spread. In the future, we hope that each pathogen will be treated with the most efficient and least invasive protocols available.

Corneal collagen cross-linking for infectious keratitis: an update of clinical studies

Collagen cross-linking (CXL) with ultraviolet light-activated riboflavin is a corneal surface procedure developed for the treatment of keratoconus and corneal ectasia. With the known microbicidal and corneal stiffening effects of ultraviolet irradiation and photoactivated riboflavin, it has recently been introduced for the management of infectious keratitis, especially for ulcers resistant to antimicrobial therapy or associated with corneal melting. Various authors have attempted to use CXL as an adjunctive, salvage or even as the sole treatment for infectious corneal ulcers. The aim of this review was to provide a summary of the clinical studies in the literature. It is worth noting that there is still no consensus on the treatment protocol of CXL against infectious keratitis. The disparities in outcome measures, treatment protocol and study design can confound the interpretation and hamper the generalization of the study results. Based on current evidence, the role of CXL in infectious keratitis remained unclear despite the reported success in some clinical cases. Further investigations are warranted concerning the efficacy and safety of treating infectious keratitis with CXL.

PACK-CXL: Corneal Cross-linking for Treatment of Infectious Keratitis

This article discusses corneal cross-linking (CXL) and how it transitioned from a modality for treating corneal ectatic disorders to an inventive means of treating infectious keratitis. Initially, CXL was successfully developed to halt the progression of ectatic diseases such as keratoconus, using the standard Dresden protocol. Later, indications were extended to treat iatrogenic ectasia developing after laser-assisted in situ keratomileusis (LASIK) and photo-refractive keratectomy (PRK). At the time, it had been postulated that the combination of ultraviolet light with riboflavin could not only biomechanically strengthen the cornea but also was capable of destroying living cells and organisms including keratocytes and pathogens. Thus a new and innovative concept of treatment for infectious keratitis emerged through the use of CXL technology. Initially only advanced infectious melting ulcers resisting standard microbicidal therapy were treated with CXL in addition to standard therapy. In subsequent studies CXL was also used to treat bacterial keratitis as first line therapy without the use of concomitant antibiotic therapy. With the increasing interest in CXL technology to treat infectious keratitis and to clearly separate its use from the treatment of ectatic disorders, a new term was adopted at the 9(th) CXL congress in Dublin for this specific indication: PACK-CXL (photoactivated chromophore for infectious keratitis). PACK-CXL has the potential to eventually become an interesting alternative to standard antibiotic therapy in treating infectious corneal disorders, and may help reduce the global burden of microbial resistance to antibiotics and other therapeutic agents.

A review of collagen cross-linking in cornea and sclera

Riboflavin/UVA cross-linking is a technique introduced in the past decades for the treatment of keratoconus, keratectasia, and infectious keratitis. Its efficacy and safety have been investigated with clinical and laboratory studies since its first clinical application by Wollensak for the treatment of keratoconus. Although its complications are encountered during clinical practice, such as infection inducing risk, minimal invasion merits a further investigation on its future application in clinical practice. Recently, collagen cross-linking in sclera shows a promising prospect. In present study, we summarized the representative studies describing the clinical and laboratory application of collagen cross-linking published in past decades and provided our opinion on the positive and negative results of cross-linking in the treatment of ophthalmic disorders.

Hyperopic correction: clinical validation with epithelium-on and epithelium-off protocols, using variable fluence and topographically customized collagen corneal crosslinking

Purpose

To report novel application of topographically-customized collagen crosslinking aiming to achieve hyperopic refractive changes. Two approaches were evaluated, one based on epithelium-off and one based on epithelium-on (transepithelial).

Methods

A peripheral annular-shaped topographically customizable design was employed for high-fluence ultraviolet (UV)-A irradiation aiming to achieve hyperopic refractive changes. A total of ten eyes were involved in this study. In group-A (five eyes), a customizable ring pattern was employed to debride the epithelium by excimer laser ablation, while in group-B (also five eyes), the epithelium remained intact. In both groups, specially formulated riboflavin solutions were applied. Visual acuity, cornea clarity, keratometry, topography, and pachymetry with a multitude of modalities, as well as endothelial cell counts were evaluated.

Results

One year postoperatively, the following changes have been noted: in group-A, average uncorrected distance visual acuity changed from 20/63 to 20/40. A mean hyperopic refractive increase of +0.75 D was achieved. There was some mild reduction in the epithelial thickness. In group-B, average uncorrected distance visual acuity changed from 20/70 to 20/50. A mean hyperopic refractive increase of +0.85 D was achieved. Epithelial thickness returned to slightly reduced levels (compared to baseline) in group-A, whereas to slightly increased levels in group-B.

Conclusion

We introduce herein the novel application of a topographically-customizable collagen crosslinking to achieve a hyperopic refractive effect. This novel technique may be applied either with epithelial removal, offering a more stable result or with a non-ablative and non-incisional approach, offering a minimally invasive alternative.