From Data to Deployment: The Collaborative Community on Ophthalmic Imaging Roadmap for Artificial Intelligence in Age-Related Macular Degeneration.

OBJECTIVE: Health care systems worldwide are challenged to provide adequate care for the 200 million individuals with age-related macular degeneration (AMD). Artificial intelligence (AI) has the potential to make a significant, positive impact on the diagnosis and management of patients with AMD; however, the development of effective AI devices for clinical care faces numerous considerations and challenges, a fact evidenced by a current absence of Food and Drug Administration (FDA)-approved AI devices for AMD. PURPOSE: To delineate the state of AI for AMD, including current data, standards, achievements, and challenges. METHODS: Members of the Collaborative Community on Ophthalmic Imaging Working Group for AI in AMD attended an inaugural meeting on September 7, 2020, to discuss the topic. Subsequently, they undertook a comprehensive review of the medical literature relevant to the topic. Members engaged in meetings and discussion through December 2021 to synthesize the information and arrive at a consensus. RESULTS: Existing infrastructure for robust AI development for AMD includes several large, labeled data sets of color fundus photography and OCT images; however, image data often do not contain the metadata necessary for the development of reliable, valid, and generalizable models. Data sharing for AMD model development is made difficult by restrictions on data privacy and security, although potential solutions are under investigation. Computing resources may be adequate for current applications, but knowledge of machine learning development may be scarce in many clinical ophthalmology settings. Despite these challenges, researchers have produced promising AI models for AMD for screening, diagnosis, prediction, and monitoring. Future goals include defining benchmarks to facilitate regulatory authorization and subsequent clinical setting generalization. CONCLUSIONS: Delivering an FDA-authorized, AI-based device for clinical care in AMD involves numerous considerations, including the identification of an appropriate clinical application; acquisition and development of a large, high-quality data set; development of the AI architecture; training and validation of the model; and functional interactions between the model output and clinical end user. The research efforts undertaken to date represent starting points for the medical devices that eventually will benefit providers, health care systems, and patients.

Foundational Considerations for Artificial Intelligence Using Ophthalmic Images.

IMPORTANCE: The development of artificial intelligence (AI) and other machine diagnostic systems, also known as software as a medical device, and its recent introduction into clinical practice requires a deeply rooted foundation in bioethics for consideration by regulatory agencies and other stakeholders around the globe. OBJECTIVES: To initiate a dialogue on the issues to consider when developing a bioethically sound foundation for AI in medicine, based on images of eye structures, for discussion with all stakeholders. EVIDENCE REVIEW: The scope of the issues and summaries of the discussions under consideration by the Foundational Principles of Ophthalmic Imaging and Algorithmic Interpretation Working Group, as first presented during the Collaborative Community on Ophthalmic Imaging inaugural meeting on September 7, 2020, and afterward in the working group. FINDINGS: Artificial intelligence has the potential to improve health care access and patient outcome fundamentally while decreasing disparities, lowering cost, and enhancing the care team. Nevertheless, substantial concerns exist. Bioethicists, AI algorithm experts, as well as the Food and Drug Administration and other regulatory agencies, industry, patient advocacy groups, clinicians and their professional societies, other provider groups, and payors (i.e., stakeholders) working together in collaborative communities to resolve the fundamental ethical issues of nonmaleficence, autonomy, and equity are essential to attain this potential. Resolution impacts all levels of the design, validation, and implementation of AI in medicine. Design, validation, and implementation of AI warrant meticulous attention. CONCLUSIONS AND RELEVANCE: The development of a bioethically sound foundation may be possible if it is based in the fundamental ethical principles of nonmaleficence, autonomy, and equity for considerations for the design, validation, and implementation for AI systems. Achieving such a foundation will be helpful for continuing successful introduction into medicine before consideration by regulatory agencies. Important improvements in accessibility and quality of health care, decrease in health disparities, and lower cost thereby can be achieved. These considerations should be discussed with all stakeholders and expanded on as a useful initiation of this dialogue.

Assessment of Clinical Trials for Devices Intended to Control Myopia Progression in Children.

The increased prevalence of myopia in the United States and other regions of the world, and the sight-threatening problems associated with higher levels of myopia have led to great interest in research designed to reduce these rates. As most of the progression of myopia occurs in childhood, these investigations have been directed toward slowing the progression of myopia in children. Treatments described to potentially slow the progression of myopia have included pharmacological interventions, multifocal spectacles, and multifocal correction created by contact lenses. Although some contact lens clinical trials have demonstrated promising results in slowing the progression of myopia, many of these studies have significant limitations, including only short follow-up times, limited randomization, and incomplete masking. Such limitations have underscored the need to develop a more robust clinical study design, so that future studies can demonstrate whether contact lenses, as well as other medical devices, can be used in a safe and effective manner to control myopia progression. We review previous key studies and discuss study design and regulatory issues relevant to future clinical trials.

Optimized Protocol for Testing Multipurpose Contact Lens Solution Efficacy Against Acanthamoeba.

OBJECTIVES: To evaluate the interlaboratory and intralaboratory reproducibility of a proposed protocol for multipurpose contact lens solution (MPS) disinfection efficacy against Acanthamoeba. METHODS: Acanthamoeba castellanii and Acanthamoeba polyphaga and four MPS with different biocidal agents were used to evaluate the protocol in two different laboratories. In addition to the negative control, a positive control and neutralization control were used. One experiment was performed in triplicate, and all other experiments were performed in duplicate in each laboratory. Acanthamoeba trophozoites were grown axenically, and cysts were generated using the starvation method. Trophozoites and cysts at a concentration of 2.0 × 10 to 2.0 × 10 organisms per milliliter were exposed to the test MPS for 0, 4 or 6 (manufacturer's recommended soak time [MRST]), 8, and 24 hr. Survivors were determined by a limiting dilution method that used a most probable number evaluation. RESULTS: The positive and negative controls displayed consistent results and trends both within each laboratory and between each laboratory for trophozoites and cysts of both A. castellanii and A. polyphaga. The neutralization control consistently demonstrated the ability of the neutralizing agents to neutralize the MPS and the positive control and demonstrated no inhibition of Acanthamoeba by the negative control. Testing in triplicate and duplicate demonstrated the reproducibility of the protocol both within each laboratory and between the laboratories. Our results demonstrated that the MPS at the MRST and at 8 hr (likely overnight soak time) are generally more effective against trophozoites than they are against cysts. Only the MPS with hydrogen peroxide as the biocidal agent was able to provide a greater than three-log kill of cysts at the MRST and longer. Among the MPS we tested, trophozoites of A. castellanii and A. polyphaga showed similar responses. Some variability was observed when testing cysts of both species. In both laboratories, one nonhydrogen peroxide containing MPS had some effect (>1 log kill) on A. polyphaga cysts. This solution had no effect (<1 log kill) on A. castellanii cysts, A. castellanii trophozoites, and A. polyphaga trophozoites. CONCLUSIONS: The protocol that we have revised and evaluated is a well-controlled and reproducible procedure that can effectively evaluate the efficacy of MPS against Acanthamoeba trophozoites. Some variability was observed when testing the cyst stage.

Food and Drug Administration, American Academy of Ophthalmology, American Academy of Optometry, American Association for Pediatric Ophthalmology and Strabismus, American Optometric Association, American Society of Cataract and Refractive Surgery, and Contact Lens Association of Ophthalmologists Co-Sponsored Workshop: Controlling the Progression of Myopia: Contact Lenses and Future Medical Devices.

The prevalence of myopia is high and increasing. Approximately 5 billion people around the world are expected to be myopic by the year 2050. Methods to slow the progression of myopia and therefore potentially decrease the associated sight-threatening complications have been the subject of a number of investigations. A workshop, sponsored by the United States Food and Drug Administration (FDA) Center for Devices and Radiological Health, American Academy of Ophthalmology, American Academy of Optometry, American Association for Pediatric Ophthalmology and Strabismus, American Optometric Association, American Society of Cataract and Refractive Surgery, and Contact Lens Association of Ophthalmologists, Inc, convened myopia experts from around the world to discuss principles to consider in the design of clinical trials investigating the effectiveness and safety of myopia control devices. Experts discussed parameters such as study endpoints, duration, enrollment criteria, patient-reported outcomes, recruitment, and retention. The discussions among the experts, FDA, and audience members should help to facilitate the development and evaluation of reasonably safe and effective myopia control devices.

The Definition of Glaucomatous Optic Neuropathy in Artificial Intelligence Research and Clinical Applications.

OBJECTIVE: Although artificial intelligence (AI) models may offer innovative and powerful ways to use the wealth of data generated by diagnostic tools, there are important challenges related to their development and validation. Most notable is the lack of a perfect reference standard for glaucomatous optic neuropathy (GON). Because AI models are trained to predict presence of glaucoma or its progression, they generally rely on a reference standard that is used to train the model and assess its validity. If an improper reference standard is used, the model may be trained to detect or predict something that has little or no clinical value. This article summarizes the issues and discussions related to the definition of GON in AI applications as presented by the Glaucoma Workgroup from the Collaborative Community for Ophthalmic Imaging (CCOI) US Food and Drug Administration Virtual Workshop, on September 3 and 4, 2020, and on January 28, 2022. DESIGN: Review and conference proceedings. SUBJECTS: No human or animal subjects or data therefrom were used in the production of this article. METHODS: A summary of the Workshop was produced with input and approval from all participants. MAIN OUTCOME MEASURES: Consensus position of the CCOI Workgroup on the challenges in defining GON and possible solutions. RESULTS: The Workshop reviewed existing challenges that arise from the use of subjective definitions of GON and highlighted the need for a more objective approach to characterize GON that could facilitate replication and comparability of AI studies and allow for better clinical validation of proposed AI tools. Different tests and combination of parameters for defining a reference standard for GON have been proposed. Different reference standards may need to be considered depending on the scenario in which the AI models are going to be applied, such as community-based or opportunistic screening versus detection or monitoring of glaucoma in tertiary care. CONCLUSIONS: The development and validation of new AI-based diagnostic tests should be based on rigorous methodology with clear determination of how the reference standards for glaucomatous damage are constructed and the settings where the tests are going to be applied. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Considerations for addressing bias in artificial intelligence for health equity.

Health equity is a primary goal of healthcare stakeholders: patients and their advocacy groups, clinicians, other providers and their professional societies, bioethicists, payors and value based care organizations, regulatory agencies, legislators, and creators of artificial intelligence/machine learning (AI/ML)-enabled medical devices. Lack of equitable access to diagnosis and treatment may be improved through new digital health technologies, especially AI/ML, but these may also exacerbate disparities, depending on how bias is addressed. We propose an expanded Total Product Lifecycle (TPLC) framework for healthcare AI/ML, describing the sources and impacts of undesirable bias in AI/ML systems in each phase, how these can be analyzed using appropriate metrics, and how they can be potentially mitigated. The goal of these "Considerations" is to educate stakeholders on how potential AI/ML bias may impact healthcare outcomes and how to identify and mitigate inequities; to initiate a discussion between stakeholders on these issues, in order to ensure health equity along the expanded AI/ML TPLC framework, and ultimately, better health outcomes for all.

Rabbit ocular reactivity to bacterial endotoxin contained in aqueous solution and ophthalmic viscosurgical devices.

OBJECTIVE: To describe the ocular reactivity of the rabbit to bacterial endotoxin contained in an aqueous medium and in a cohesive and a dispersive ophthalmic viscosurgical device (OVD). DESIGN: Experimental, randomized animal study. PARTICIPANTS: Seventy-five New Zealand white rabbits. METHODS: This study was performed using 75 rabbits to evaluate the ocular reactivity to bacterial endotoxin contained in Dulbecco's phosphate-buffered saline (DPBS), a cohesive OVD, and a dispersive OVD. For each test material, 25 rabbits were randomized into 5 groups and were exposed to the test material containing 0.75 endotoxin units (EU), 0.25 EU, 0.08 EU, and 0.02 EU of endotoxin or the vehicle control. The rabbits in each group received bilateral intracameral injection of 0.05 ml of the same test material. All eyes were examined by slit-lamp biomicroscopy at baseline, 3, 6, 9, 24, 48, and 72 hours after injection. At 24 and 72 hours, slit-lamp biomicroscopy (and additionally indirect ophthalmoscopy) was performed through dilated pupils. MAIN OUTCOME MEASURES: Corneal clouding, anterior chamber (AC) flare, cells and fibrin, vitreous haze and cells, cells and fibrin on lens surface, lens opacities, and onset time. RESULTS: The inflammation seen after exposure to the 3 endotoxin-spiked materials followed the same general time course. Anterior chamber cells, flare, iris hyperemia, and conjunctival congestion were seen as early as 3 hours. They started to diminish after 6 hours (DPBS eyes) and 9 hours (OVDs) and were not detectable at 48 and 72 hours, respectively. The AC inflammation was more severe in the OVD eyes than in the DPBS eyes. Anterior chamber fibrin was seen in the OVD eyes only, which persisted through 72 hours in many eyes. A trend toward a dose-response relationship was seen for AC cells and flare and the presence of cells and fibrin on the lens surface in all 3 treatment groups in the first 24 hours. CONCLUSIONS: Inflammation was seen after intracameral injection of as little as 0.02 and 0.08 EU in OVD and DPBS eyes, respectively. Observed responses to intracamerally injected endotoxin in OVDs were more severe and of longer duration than those in aqueous medium.

Detecting endotoxin contamination of ophthalmic viscosurgical devices: intracameral versus intravitreal assays in rabbits.

OBJECTIVE: To compare the sensitivities of intracameral and intravitreal assays in the rabbit model to determine the relative adequacy of these methods in detecting bacterial endotoxin contamination of ophthalmic viscosurgical devices (OVDs). DESIGN: Experimental, randomized animal study. PARTICIPANTS: Twenty New Zealand white rabbits. METHODS: Rabbits were randomized into 4 groups to receive a cohesive or a dispersive OVD via intracameral or intravitreal injection. All 40 treated eyes (10 eyes of 5 animals in each group) received bilateral injection of OVD spiked with bacterial endotoxin at 7.0 endotoxin units/ml. All eyes were evaluated by slit-lamp biomicroscopy for inflammatory response at 3, 6, 9, 24, 48, and 72 hours after exposure. Eyes that received intravitreal injection were also dilated at 24, 48, and 72 hours and were re-examined by slit-lamp biomicroscopy and by indirect ophthalmoscopy. MAIN OUTCOME MEASURES: Conjunctival inflammation, anterior chamber (AC) flare, cells and fibrin, vitreous haze and cells, iridal hyperemia, corneal clouding, lens opacities, and onset times. RESULTS: Intracamerally injected eyes frequently showed conjunctival congestion, AC cells and flare, iridal hyperemia, and fibrin within 6 hours. Up to 80% showed AC cells and flare at 9 hours, and up to 70% showed fibrin at 24 hours. These signs diminished within 48 hours. Fibrin and cells also were seen on the lens surface of most of the eyes. Intravitreally injected eyes showed no signs of inflammation within 24 hours, other than some conjunctival inflammation. After the 24-hour time point, in addition to some conjunctival inflammation, some other signs of inflammation were observed infrequently in the intravitreally injected eyes, including minor vitreous cell reaction in 2 eyes. Although there was 1 dispersive OVD-treated eye with cells and fibrin on the lens capsule at 48 hours, no aqueous cells or flare were seen in the AC of any intravitreally injected eyes at any time during the course of the study. CONCLUSIONS: The rabbit intravitreal assay, when limited to 72 hours, does not seem to have adequate sensitivity to detect endotoxin reliably in OVDs.

Evaluation of intraocular reactivity to metallic and ethylene oxide contaminants of medical devices in a rabbit model.

OBJECTIVE: To evaluate the intraocular reactivity to metallic and ethylene oxide (EO) contaminants of ophthalmic devices in rabbits. DESIGN: Two experimental animal studies. PARTICIPANTS: Thirty-five New Zealand white rabbits. METHODS: A metallic exposure study and an EO exposure study were performed. In the first study, both eyes of 25 rabbits were equally allocated to intracameral injections of alumina 0.2 µg, alumina 20 µg, copper sulfate 0.4 µg, copper sulfate 20 µg, or an aqueous control. In the second study, 10 rabbits were allocated (5 per group) to receive intracamerally an ophthalmic viscosurgical device (OVD) exposed to EO or not exposed to EO (control). All eyes were examined by slit lamp at baseline and 3, 6, 9, 24, 48, and 72 hours after exposure, with dilated indirect ophthalmoscopy being performed at 24 and 72 hours. Tonometry was performed only in the first study. MAIN OUTCOME MEASURES: Grade of corneal clouding, anterior chamber (AC) flare, AC cells, AC fibrin, iridal hyperemia, cell and fibrin on the lens surface, vitreous haze and cells, lens opacities, intraocular pressure, and onset time. RESULTS: For metallic compounds at the study's low doses, mean inflammatory grades were 0.2 or less above the control for all responses at all time points. For the high-dose alumina, mean inflammatory grades peaked at 6 to 9 hours at 0.5 to 0.7 above the control responses for conjunctival congestion, iris hyperemia, AC cells, flare, and fibrin and declined over the remaining time points. For the high-dose copper sulfate, mean inflammatory grades peaked between 3 and 24 hours at 1.2 to 1.8 above the control responses for conjunctival congestion, iris hyperemia, AC cells, flare, fibrin, and corneal clouding, then subsequently declined. The intraocular pressure changes appeared significant for only high-dose copper sulfate, with mean declines of 4.3 to 7.5 mmHg at 6 to 72 hours. No clinically meaningful differences in ocular inflammation were observed between the OVD exposed to EO and the OVD not exposed to EO. CONCLUSIONS: Alumina and copper sulfate did not cause clinically meaningful ocular inflammation at the low study levels (levels expected with ophthalmic devices). Ethylene oxide exposure of an OVD was not associated with inflammation.

The Food and Drug Administration's Proactive toxic anterior segment syndrome Program.

Toxic anterior segment syndrome (TASS) is a rare inflammatory condition usually observed within the first 48 hours after uncomplicated anterior segment surgery. Over the decades since its initial description, a number of TASS outbreaks have been reported. For a few of these outbreaks, the inciting factors were identified, but for the majority, the precipitating factors were often postulated but not confirmed. In light of the limitations identified in these outbreak investigations, the Food and Drug Administration's (FDA's) Center for Devices and Radiological Health staff has embarked on a number of activities aimed at mitigating medical device-related TASS outbreaks. Under the FDA-designed Proactive TASS Program (PTP), FDA scientists have conducted animal studies to better explore the inflammatory potential of suspected ophthalmic device contaminants implicated in prior cases of TASS. For contaminants displaying a TASS-like reaction in these animal models, the FDA scientists have developed analytic test methods to measure the level of those contaminants in or on ophthalmic devices. Moreover, FDA researchers have developed methods to better capture the clinical information necessary to assist investigations of potential future outbreaks. Last, the FDA has partnered with the Centers for Disease Control and Prevention to facilitate a potential TASS investigation, including expediting the analysis of potentially contaminated medical devices. The PTP is an example of the FDA proactively developing test methods and disease surveillance methods geared toward protecting the public's health.

Rabbit intraocular reactivity to endotoxin measured by slit-lamp biomicroscopy and laser flare photometry.

OBJECTIVE: To evaluate the ocular reactivity of the rabbit to an intracameral injection of a dispersive ophthalmic viscosurgical device (OVD) containing various levels of bacterial endotoxin using slit-lamp biomicroscopy and laser flare photometry. DESIGN: Experimental, randomized, masked animal study. PARTICIPANTS: Thirty Dutch-Belted rabbits. METHODS: The rabbits were randomized into 6 groups to receive 0.05 ml of a hydroxypropyl methylcellulose-based dispersive OVD to which had been added one of 5 different doses of bacterial endotoxin ranging from 0.02 to 1.4 endotoxin units (EUs) or a vehicle control to both eyes. The eyes were evaluated for anterior segment inflammation at baseline and 3, 6, 9, 24, 48, and 72 hours after injection using slit-lamp biomicroscopy and laser flare photometry. MAIN OUTCOME MEASURES: Corneal clarity and anterior chamber (AC) inflammation. RESULTS: All the corneas remained clear throughout the study. Anterior chamber cells were seen at 6, 9, and 24 hours in 60% to 100% of the eyes intracamerally injected with endotoxin-containing OVD, and the response declined rapidly after 24 hours. A dose-response effect was seen between the concentration of endotoxin and the AC cell response. The aqueous flare response in eyes injected with the 2 highest doses of endotoxin was significantly greater (P<0.05) than that of controls. The amounts of fibrin observed in the AC were random, with no apparent dose-response effect seen. The flare values as obtained by laser flare photometry were consistent with the slit-lamp biomicroscopy flare findings up to grade 3+. However, the increase in laser flare value seemed to level off in eyes with more than 3+ flare. Neither measure of flare correlated with endotoxin level. CONCLUSIONS: Among the parameters evaluated in this study, the AC cell response, evaluated by slit-lamp biomicroscopy and graded using a standard grading system, was found to be the most reliable indicator of the amount of endotoxin in the dispersive OVD. The use of laser flare photometry alone does not seem to be useful in detecting an ocular response to endotoxin contamination in OVDs.

Evaluation of intraocular reactivity to organic contaminants of ophthalmic devices in a rabbit model.

OBJECTIVE: To evaluate the intraocular reactivity to organic contaminants of ophthalmic devices in the rabbit. DESIGN: Experimental animal study. PARTICIPANTS: Fifty New Zealand white rabbits. METHODS: The rabbits were allocated to 10 groups of 5 each to receive 2 different doses of human albumin and nonhuman nucleic acids and their respective vehicle controls, a denatured cohesive ophthalmic viscosurgical device (OVD) and a denatured dispersive OVD and their respective nondenatured controls. All 10 eyes in each treatment group received bilateral intracameral injection of the test materials. All the eyes in the study were examined by slit-lamp biomicroscopy at baseline and 6, 9, 24, 48, and 72 hours. Pachymetry was also performed on eyes exposed to albumin, protein vehicle control, and the OVDs at these time points. MAIN OUTCOME MEASURES: Corneal thickness, grade of corneal clouding, anterior chamber (AC), cells, flare and fibrin, iridal hyperemia, cell and fibrin on lens surface, and onset time. RESULTS: There were no inflammatory signs in any eyes exposed to human albumin. Anterior chamber cells (1+ to 3+) and flare and fibrin (1+ to 2+), along with cells and fibrin on the lens surface, were seen in the eyes exposed to the nucleic acid samples, and they resolved in 24 hours. Mild (mostly 1+) conjunctival congestion, cells, flare, and fibrin were seen in a few eyes exposed to the 2 denatured OVDs and their controls, with the response durations being shorter in the denatured OVD eyes (24 hours) than in the nondenatured OVD eyes (48 hours). Anterior chamber inflammation was generally observed in fewer denatured OVD eyes than in nondenatured OVD eyes, particularly the dispersive OVD eyes. CONCLUSIONS: Intracameral injection of human albumin protein did not cause ocular inflammation. Nucleic acid intracamerally injected into rabbit eyes caused acute inflammation that quickly resolved. Cohesive and dispersive OVD denatured by drying and steam sterilization alone did not cause ocular inflammation.

An investigation of enzymatic detergents as a potential cause of toxic anterior segment syndrome.

OBJECTIVE: To investigate whether enzymatic detergents used in cleaning ophthalmic surgical instruments can cause toxic anterior segment syndrome (TASS)-like responses in a rabbit model. DESIGN: Randomized, investigator-masked, controlled experimental animal study. PARTICIPANTS: Thirty-five New Zealand white rabbits. METHODS: The rabbit eyes were randomized into 7 treatment groups to receive intracameral injection of 1 of 3 different doses of Medline Dual Detergent or Enzol Detergent, or sterile limulus amoebocyte lysate reagent water as a control. The eyes were evaluated for anterior segment inflammation at baseline and at 1, 3, 6, 24, 48, and 72 hours after treatment by slit-lamp biomicroscopy. MAIN OUTCOME MEASURES: Anterior chamber (AC) inflammation, including cells, flare, fibrin, and iris injection; time course of inflammation; and residual detergent levels in luminated instruments. RESULTS: Moderate to marked injection of the iris vessels was seen as early as 1 hour after treatment with the enzymatic detergents in 41 of 60 eyes, with the response being more severe in the Enzol Detergent-exposed eyes. Severe iris hemorrhages were accompanied by blood in the AC in 13 eyes, which usually persisted through 72 hours, with an associated increase in AC cell and flare. Corneal haze was present in 52 of 56 eyes 1 hour after treatment, but was mild and resolved within 24 hours in all but the Enzol 4.5%-exposed eyes. Median AC cell and flare peaked at 6 hours and resolved by 48 hours. CONCLUSIONS: Enzymatic detergents caused a severe but unusual response from the iris when injected intracamerally into rabbit eyes. This response has not been reported in humans with TASS. The time course of inflammation was faster (peak at 6 hours) and resolved more quickly (within 48 hours) than TASS. Simulated cleaning and extraction studies indicate that the level of residual detergent to which a patient could be exposed is significantly less than the lowest dose used in this study. Because that low dose caused no significant observations other than injection of the iris vessels, these results do not support residual enzymatic detergents on surgical instruments as a cause for TASS.

Strategies to optimize conditions for testing multipurpose contact lens solution efficacy against Acanthamoeba.

OBJECTIVES: To optimize the growth, culture, and life cycle conditions for testing multipurpose solutions (MPS) against Acanthamoebatrophozoites and cysts to better inform the development of an appropriate test protocol. METHODS: Two strains of Acanthamoeba castellanii were grown using 2 different methods, bacterized and axenic. Amoebae grown from both methods and from both strains were treated with 4 different MPS as trophozoites and cysts, which were generated using 4 encystment methods. Experiments were run in triplicate with controls. A 5-tube most probable number method was used to enumerate the survivors and to determine the log kills. Statistical analysis was performed using effect screening. RESULTS: There was a marked difference in effectiveness among solutions, which varied with growth conditions (P<0.0001) and encystment method. Growth medium affected survival. In addition, there was a significant difference in cyst survival, which was dependent on encystment method (P=0.0013). The strain used was less of a factor in trophozoite resistance to MPS. Cyst resistance to MPS varied depending on which strain was used, but it was not a significant factor. CONCLUSIONS: When designing a contact lens solution efficacy testing protocol for Acanthamoeba, care should be taken to control for variables that may distort results. An appropriate protocol should include growing Acanthamoeba bacterized and allowing them to encyst naturally. By choosing optimized testing conditions, a more realistic efficacy of contact lens solutions can be determined which will result in better and safer products on the market.

The effects of contact lens materials on a multipurpose contact lens solution disinfection activity against Staphylococcus aureus.

OBJECTIVES: To determine the effect of 8 different lens materials on polyhexamethylene biguanide (PHMB) concentration in multipurpose solution (MPS) levels over time and to determine the effect of lenses on lens solution microbial efficacy over time. METHODS: Silicone hydrogel lenses and conventional hydrogel lenses were soaked in polypropylene lens cases filled with contact lens MPS containing 1 ppm PHMB for 6, 12, 24, 72, and 168 hours. Cases filled with the same solution without lenses were controls. After each time period, solutions from cases with the 8 types of lenses and controls were assayed for activity against Staphylococcus aureus according to International Organization for Standardization-14729 with modifications. Solutions were analyzed for PHMB concentration at each time point. RESULTS: Some of the different lens materials significantly affected the PHMB concentration (P<0.0001) and the biocidal efficacy. Etafilcon A lenses significantly decreased PHMB levels after only 6 hours of lens soak time. The product lot of MPS used was also significant (P<0.0001). Enfilcon A, senofilcon A, and lotrafilcon B lenses did not significantly decrease PHMB levels. CONCLUSIONS: The efficacy of MPS was affected by some lens materials and PHMB concentration. Lens materials differ in their effect on PHMB concentration and the subsequent efficacy of the MPS. Over time, some lens materials can significantly reduce the PHMB concentration and the MPS's microbial activity against S. aureus.

The effect of contact lens materials on disinfection activity of polyquaternium-1 and myristamidopropyl dimethylamine multipurpose solution against Staphylococcus aureus.

OBJECTIVES: This study examined the interaction of seven different lens materials with a multipurpose solution (MPS) containing the disinfectants polyquaternium-1 (0.001%) and myristamidopropyl dimethylamine (0.0005%). The objective of this study was to determine whether the different lens materials affect the concentration of a disinfectant in this commercially available MPS and the efficacy of the disinfectant against Staphylococcus aureus. METHODS: Silicone hydrogel lenses (galyfilcon A, senofilcon A, comfilcon A, enfilcon A, balafilcon A, and lotrafilcon B) and a conventional hydrogel lens (etafilcon A) were soaked in polypropylene lens cases filled with commercially available MPS containing 0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine for 6, 12, 24, 72, and 168 hours. Empty lens cases were also filled with MPS. After each time point, solutions from cases containing the seven types of lenses and controls were assayed for activity against S. aureus according to International Standards Organization 14729 standard with modifications. Test solutions were analyzed for polyquaternium-1 and myristamidopropyl dimethylamine concentration at each time point. RESULTS: The concentration of polyquaternium-1 and myristamidopropyl dimethylamine remaining in the lens cases was reduced only slightly over time. Storage with the lenses did not adversely affect biocidal efficacy of the solution, and in some cases, it was significantly better (P=0.0029). CONCLUSION: The efficacy of this polyquaternium-1 and myristamidopropyl dimethylamine MPS to kill S. aureus was not adversely affected by the presence of lens materials soaking in the cases. Thus, current methods for performing solution antimicrobial testing should be reevaluated.

Impact of contact lens materials on multipurpose contact lens solution disinfection activity against Fusarium solani.

OBJECTIVE: To investigate the effects of eight different soft contact lenses on disinfection efficacy of a multipurpose solution (MPS) containing polyhexamethylene biguanide (PHMB) against Fusarium solani. METHODS: Six silicone hydrogel lenses (galyfilcon A, senofilcon A, comfilcon A, enfilcon A, balafilcon A, and lotrifilcon B) and two conventional hydrogel lenses (polymacon and etafilcon A) were placed in polypropylene lens cases filled with MPS containing 0.0001% PHMB and soaked for 6, 12, 24, 72, and 168 hours. After each interval, depleted MPS from lens cases were removed and assayed for activity against F. solani according to International Organization for Standardization (ISO) 14729 stand-alone procedure. A portion was aliquoted for chemical analysis. RESULTS: Soaking etafilcon A, balafilcon A, and polymacon lenses for 6 hours reduced the concentration of PHMB in MPS by more than half the stated labeled concentration, with concentrations below the limit of detection for etafilcon A-depleted and balafilcon A-depleted solutions after 12 and 72 hours of soaking, respectively. Except for comfilcon A-depleted solutions, all others failed to consistently obtain one log reduction of F. solani. The solutions soaked with etafilcon A, balafilcon A, and polymacon lenses for 24 hours or more lost all or almost all fungicidal activity against F. solani. CONCLUSIONS: Over time, the disinfectant uptake by some lenses can significantly reduce the PHMB concentration and the fungicidal activity of the MPS against F. solani. Current ISO methodology does not address the reduction in microbiocidal efficacy when lenses are soaked in MPS. The ISO committee should consider adding "soaking experiments" to quantify the effect that contact lens materials have on the performance of MPSs.

Material properties that predict preservative uptake for silicone hydrogel contact lenses.

OBJECTIVES: To assess material properties that affect preservative uptake by silicone hydrogel lenses. METHODS: We evaluated the water content (using differential scanning calorimetry), effective pore size (using probe penetration), and preservative uptake (using high-performance liquid chromatography with spectrophotometric detection) of silicone and conventional hydrogel soft contact lenses. RESULTS: Lenses grouped similarly based on freezable water content as they did based on total water content. Evaluation of the effective pore size highlighted potential differences between the surface-treated and non-surface-treated materials. The water content of the lens materials and ionic charge are associated with the degree of preservative uptake. CONCLUSIONS: The current grouping system for testing contact lens-solution interactions separates all silicone hydrogels from conventional hydrogel contact lenses. However, not all silicone hydrogel lenses interact similarly with the same contact lens solution. Based upon the results of our research, we propose that the same material characteristics used to group conventional hydrogel lenses, water content and ionic charge, can also be used to predict uptake of hydrophilic preservatives for silicone hydrogel lenses. In addition, the hydrophobicity of silicone hydrogel contact lenses, although not investigated here, is a unique contact lens material property that should be evaluated for the uptake of relatively hydrophobic preservatives and tear components.