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. A review of techniques for analysing hydrogel lens deposition J BCLA 199036-41

. Disposable and planned replacement systems - a review Optometry Today 1991, July: 16-20

. Daily-wear Acuvue disposable lenses - a review Die Kontaklinse 1992;2112-16

. Disposable lenses for daily wear Irish Optician 1994;4, 4: 22-24

. BCLA continuing education questionnaire Optometry Today 1994, January: 16-20

. Currently available disposable contact lens systems Optician 1995;209, 5500: 16-22

. Chronic blepharitis - a case study CE Optometry 1997;122-23

. Dimple-veil staining - a case study CE Optometry 1997;120

. Toric calculations made simple (product review) Optician 1997;213, 5587: 34

. Assessment of corneal staining in clinical practice CE Optometry 1998;153-55

The IACLE Contact Lens Course IACLE. 2009.

Abdi,B., Mofidfar,M., Hassanpout,F., Cilingir,E. K., Kalajahi,S., Milani,P. K., Ghanbarzadeh,M., Fadel,D., Barnett,M., Ta,C. N., Leblanc,R. M., Chauhan,A., Abbasi,F. Therapeutic contact lenses for the treatment of corneal and ocular surface diseases: Advances in extended and targeted drug delivery International Journal of Pharmaceutics 2023;638(May):122740 [ Show Abstract ]

The eye is one of the most important organs in the human body providing critical information on the environment. Many corneal diseases can lead to vision loss affecting the lives of people around the world. Ophthalmic drug delivery has always been a major challenge in the medical sciences. Since traditional methods are less efficient (∼5%) at delivering drugs to ocular tissues, contact lenses have generated growing interest in ocular drug delivery due to their potential to enhance drug bioavailability in ocular tissues. The main techniques used to achieve sustained release are discussed in this review, including soaking in drug solutions, incorporating drug into multilayered contact lenses, use of vitamin E barriers, molecular imprinting, nanoparticles, micelles and liposomes. The most clinically relevant results on different eye pathologies are presented. In addition, this review summarizes the benefits of contact lenses over eye drops, strategies for incorporating drugs into lenses to achieve sustained release, results of in vitro and in vivo studies, and recent advances in the commercialization of therapeutic contact lenses for allergic conjunctivitis.

Akbari,E., Imani,R., Shokrollahi,P., Keshel,S. H. Corneal sustained delivery of hyaluronic acid from nanofiber-containing ring-implanted contact lens Journal of Biomaterials Application 2023;37(6):992-1006 [ Show Abstract ]

Dry eye syndrome, as a persist corneal epithelial defect (PED), is an inconvenient ocular disorder that is generally treated by high-dosage, conventional eye drops. Addressing low efficacy and rather restricted bioavailability of the conventional eye drops, drug-eluting contact lenses (CLs) are widely used as alternatives in ophthalmic drug delivery applications. In the present study, a nanofiber-containing ring implant poly (vinyl alcohol) (PVA) hydrogel is designed as a carrier for hyaluronic acid (HA) delivery. hyaluronic acid is physically encapsulated in a nanofiber-containing ring-shaped hydrogel with a 2 mm width that is implanted in the final CLs hydrogel. The designed CL has 59% porosity, 275% swelling ratio and undergoes no weight loss at physiological conditions in14 days. In-vitro release studies were performed on the CLs with and without nanofibers. The results showed that nanofiber incorporation in the designed CL was highly influential in decreasing burst release and supported sustained release of HA over 14 days. In addition, nanofiber incorporation in the designed system strengthened the lens, and the young modulus of the PVA hydrogel increased from 6 to 10 kPa. Cell viability study also revealed no cell cytotoxicity and cell attachment. Overall, the study demonstrated the effective role of nanofibers in the physical strengthening of the CL. Also, the designed system holds promise as a potential candidate for HA delivery over an extended period for treating dry eye syndrome.

Al Atrach,M., Phan.C-M., Jones,L. Extended release of ciprofloxacin from commercial contact lenses containing vitamin E diffusion barriers Optometry and Vision Science 2024;101(11):666-676 [ Show Abstract ]

SIGNIFICANCE
Vitamin E could be used as a coating with commercial silicone hydrogel lenses to extend the release of various ophthalmic drugs. This concept could provide a promising approach to improve overall ocular therapeutic outcomes for topical ocular drugs.

PURPOSE
This study aimed to develop a contact lens–based ocular drug delivery system using vitamin E as a diffusion barrier to extend the release duration of ciprofloxacin.

METHODS
Five commercial lenses were soaked for 24 hours in various concentrations of vitamin E dissolved in ethanol (0.0125 to 0.2 g/mL). The lenses were loaded with ciprofloxacin for 24 hours in 3 mL of 3 mg/mL of ciprofloxacin/acetic acid solution. The drug release was evaluated in 3 mL of phosphate-buffered saline solution. At t = 0.5, 1, 2, 4, 6, 8, 12, 16, and 24 hours, the amount of ciprofloxacin released was measured using a UV-VIS spectrophotometer at 270 nm.

RESULTS
There was a decrease in ciprofloxacin loading with increasing amounts of vitamin E loaded into the silicone hydrogel lenses. For each lens type, there was an optimal amount of vitamin E loaded that extended the release duration of the drug from 1 hour (without vitamin E) to as long as 16 hours. In contrast, vitamin E loaded into hydrogel lenses had no effect on the amounts of drugs loaded or the release duration.

CONCLUSIONS
Vitamin E can be used as a diffusion barrier with commercially available silicone hydrogel lenses to provide sustained release of ciprofloxacin. The results suggest that vitamin E may form blockages in channels within a silicone hydrogel lens material, thereby forcing a longer path for drugs to diffuse into and out of the lens material. There is an optimal amount of vitamin E that needs to be loaded to extend the release duration, and this is lens material dependent.

Alexander C, Jones L, Moody K. Evidence-based contact lens prescribing decisions Covalent Careers webinar, USA, November, 2020

Alexander C, Jones L, Moody K. Evidence-based contact lens prescribing decisions Johnson & Johnson Vision webinar, USA, September, 2020

Anderson T, Moezzi A, Varikooty J, Jones L, Woods C, Fonn D. A novel method for measuring contact lens movement and centration using a high speed camera and computer vision Optom Vis Sci 2011;88:E-abstract 115439

Arvind,A., Najappa,R., Gupta,K. K., Macedo-De-Araujo,R. J., Fadel,D. Lid wiper epitheliopathy: Topical review of current identification strategies and future perspectives Contact Lens Anterior Eye 2024;47(6):102312 [ Show Abstract ]

Lid Wiper Epitheliopathy (LWE) is a recognized ocular condition affecting visual quality and ocular comfort, characterized by the damage of the marginal conjunctiva of the upper eyelid. This review critically examines the current strategies for LWE identification and explores the multifactorial etiology of LWE and its association with various ocular surface diseases. A literature review conducted on PubMed identified 67 relevant studies, which were analyzed to enhance understanding of LWE’s diagnostic criteria and its clinical implications, offering future perspectives on improving diagnostic accuracy and patient outcomes.

The association between LWE and contact lens-related discomfort is examined, with studies reporting conflicting findings regarding its prevalence and severity among soft contact lens wearers. Moreover, LWE has been linked to tear film abnormalities, altered tear composition, and eyelid margin abnormalities in non-contact lens wearers, further complicating diagnosis and management.

Current LWE grading systems, including subjective methods and semi-objective approaches, are reviewed, highlighting challenges such as subjectivity, complexity, and variability. Recent advances in LWE grading, including semi-automated methods and photographic scales, show promise but face implementation challenges in clinical settings.

The review concludes by proposing areas for further research, including investigating factors contributing to LWE onset and development, developing more sensitive diagnostic tools, and exploring the impact of LWE on ocular surface health and visual function. Standardization, validation, and innovation in grading systems are emphasized to enhance diagnostic accuracy and improve clinical outcomes for patients with LWE. Ongoing research in LWE grading is essential for addressing diagnostic challenges and optimizing assessment methodologies in clinical practice.

Averbeck K, Jones D, Westall C. A comparison of two logmar-based crowded visual acuity tests for the assessment of vision in children American Academy of Optometry, Orlando, 2000

Aziz,A., Kuppusamy,R., Mazumder,K., Hui,A., Maulvi,F., Stapleton,F., Willcox,M. Absorption and attachment of atropine to etafilcon A contact lenses Contact Lens Anterior Eye 2024;47(5):102246 [ Show Abstract ]

Purpose: Myopia (short-sightedness) is a growing vision problem worldwide. Currently atropine eye drops are used to control the progression of myopia but these suffer from potential lack of bioavailability and low ocular residence time. Commercially available myopia control contact lenses are also used to limit myopia progression, but neither atropine nor contact lenses individually completely stop progression. Development of myopia control contact lenses which could deliver therapeutic doses of atropine is thus desirable and may provide increased efficacy. This study was designed to explore the feasibility of attaching atropine to etafilcon A contact lenses through an esterification reaction.

Methods: Carboxylic acid groups on etafilcon A contact lenses were quantified using Toluidine Blue O. The carboxylic acid groups in etafilcon A contact lenses were activated using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC-HCl) and N-hydroxysuccinimide (NHS) crosslinkers after which atropine was added to undergo potential binding via esterification. Atropine was released from lenses by alkaline hydrolysis. Reverse phase high performance liquid chromatography (HPLC) was used to detect and quantify the released atropine and its degradation products in solution. Contact lenses that had not been activated by EDC-NHS (controls) were also examined to determine the amount of atropine that could be absorbed rather than chemically bound to lenses.

Results: Each etafilcon A contact lens contained 741.1 ± 5.5 µg carboxylic acid groups which may be available for esterification. HPLC had a limit of detection for atropine of 0.38 µg/mL and for tropic acid, an atropine degradation product, of 0.80 µg/mL. The limits of quantification were 1.16 µg/mL for atropine and 2.41 µg/mL for tropic acid in NH4HCO3. The etafilcon A lenses adsorbed up to 7.69 μg atropine when incubated in a 5 mg/mL atropine solution for 24 h. However, there was no evidence that atropine could be chemically linked to the lenses, as washing in a high concentration of NaCl removed all the atropine from the contact lenses with no atropine being subsequently released from the lenses after incubating in 0.01 N NH4HCO3.

Conclusions: Etafilcon A contact lenses contain free carboxylic acids which may be an appropriate option for attaching drugs such as atropine. Etafilcon A lenses adsorbed up to 7.69 μg atropine, which would be more than enough to deliver atropine to eyes to control myopia. However, atropine could not be chemically bound to the carboxylic acids of the etafilcon A lenses using this methodology.

Babaei Omali N, Subbaraman L, Coles-Brennan, Fadli Z, Jones L. Selective uptake of lysozyme by various hydrogel contact lens materials Invest Ophthalmol Vis Sci 2015;56: E-abstract 6109 [ PDF ]

Babaei Omali N, Subbaraman L, Heynen M, Thangavelu M, Dare E, Canavan K, Fadli Z, Jones L. Protein Deposition on Senofilcon A Contact Lenses in Symptomatic and Asymptomatic Lens Wearers Optom Vis Sci 2014;91: E-abstract 145186 [ PDF ]

Babaei Omali N, Subbaraman L, Schulze M, Heynen M, Canavan K, Fadli Z, Jones L. Clinical Signs, Symptoms, Tear Film and Meibum Composition in Asymptomatic Senofilcon A Contact Lens and Spectacle Wearers Optom Vis Sci 2014;91: E-abstract 145185 [ PDF ]

Back A, Chamberlain P, Logan N, Jones D, Gonzalez-Meijome J, Mei Saw S, Young G. Clinical evaluation of a dual-focus myopia control 1 day soft contact lens - 2-year results Optom Vis Sci 2016;93: E-abstract 160035