Wide Variation of Squeezing Force and Dispensing Time Interval among Eyedropper Bottles

Optimizing instilled drug delivery: a scoping review of microdrops in ophthalmology

Eyedrop instillation constitutes the most commonly used ocular drug delivery method that serves for both diagnostic and therapeutic purposes. Ocular disposition and bioavailability of instilled drugs depend on the anatomy and physiology of the ocular surface as well as the physicochemical properties of the active agent. Intraocular bioavailability is positively associated with the amount of drug available onto the ocular surface and the precorneal residence time. Concerns are raised regarding systemic absorption of the instilled drugs intraocularly, percutaneously, via the conjunctiva, through the nasolacrimal system, or through the nasal, oral, and gastrointestinal mucosa. Special considerations exist regarding the anatomical features and the limited pharmacokinetic data on the pediatric population that complicate further the efficacy and systemic toxicity of the instilled medications. Both preclinical and clinical studies propose the reduction of the instilled drop volume, in the form of microdrops, as a means to enhance intraocular bioavailability of topically applied drugs, while minimizing patient discomfort and systemic adverse events. We summarize existing data on the clinical application of microdrops in a wide age range, from preterm infants to elderly adults. Studies regarding microdrops of mydriatics and ocular hypotensives show promising results in optimizing the provided everyday care.

Squeezability of eye drop containers used in dry eye disease management

CLINICAL RELEVANCE

Ocular lubricants are the mainstay of dry eye management and are available in a variety of formulations and bottle designs. The squeezability of ocular lubricant bottles may influence administration and compliance.

BACKGROUND

A key component for managing dry eye disease is the use of ocular lubricants. The different bottle types, each with their unique material strength and dispensing mechanism, may be challenging for patients with limited hand and pinch strength. The aim of this study was to evaluate the force required to expulse a drop from different eye drop containers used in the management of dry eye disease.

METHODS

The force, in newtons (N), required to expulse a drop from different eye drops was evaluated five times using a force gauge, and divided by bottle type, i.e. tubes, unidose, multidose with preservatives, and multidose preservative free (MDPF) bottles.

RESULTS

Sixty (n = 60) bottles were examined with 57 eye lubricants and 3 dry eye medications (cyclosporine (0.5% and 0.9%), and lifitegrast). The average force varied depending on the bottle type (tubes 4.28 ± 1.29 N; unidose 14.24 ± 4.83 N; multidose 16.62 ± 5.21 N; MDPF 26.68 ± 8.32 N, p < 0.001). Post-hoc test revealed that MDPF bottles required more force than all other bottle types (p < 0.001), and among those, the ophthalmic squeeze dispenser bottle required significantly more force (p < 0.001). Lifitegrast required more force (17.38 ± 2.13 N) than cyclosporine 0.5% (9.16 ± 0.80 N, p < 0.024) and cyclosporine 0.9% (5.68 ± 0.40 N, p < 0.001), but was not significantly different from unidose ocular lubricants (p > 0.05).

CONCLUSION

The squeezability of bottles used in dry eye disease management varies with bottle type. Hand and pinch strength should be considered when choosing products for dry eye disease management, as the squeezability of an ophthalmic drop can influence its administration and compliance.

Artificial Tears: A Systematic Review

Artificial tears are the mainstay of dry eye disease management, but also have a role in corneal abrasion and wound healing, pain and inflammation management, conjunctivitis, keratitis, contact lens rewetting and removal, and foreign body removal. A systematic review of randomized controlled trials (PROSPERO registration CRD42022369619) comparing the efficacy of artificial tears in patients with dry eye to inform prescribing choices using Web of Science, PubMed and Medline databases identified 64 relevant articles. There is good evidence that artificial tears improve symptoms of dry eye disease within a month of regular use, applied about four times a day, but signs generally take several months to improve. Not all patients with dry eye disease benefit from artificial tears, so if there is no benefit over a month, alternative management should be considered. Combination formulations are more effective than single active ingredient artificial tears. Artificial tears containing polyethylene glycol are more effective than those containing carboxymethylcellulose/carmellose sodium and hydroxypropyl methylcellulose. Those classified as having evaporative dry eye disease, benefit from artificial tears with liposomes, especially of higher concentration. The data available is limited by the definition of dry eye disease applied in published studies being variable, as well as the disease severity examined and compliance with artificial tears being rarely quantified.

Investigation of visual and physical factors associated with inadequate instillation of eyedrops among patients with glaucoma

Purpose

The aim of this study was to investigate the frequency of eyedrop instillation failure and its related physical and visual function factors among glaucoma patients who used hypotensive eyedrops daily.

Subjects and methods

Patients with a history of self-instillation of one or more ocular hypotensive ophthalmic solutions for six or more months were enrolled. Definitions of instillation failure were eyedrop instillation other than on the eye surface; eyedrop contact with eyelashes; eyedrop bottle tip contact with the eyelashes, eye surface or ocular adnexa; or two or more drops instilled with one instillation trial. To clarify factors related to instillation failure, we used visual function tests and investigated cervical spine extension angles during instillation, pinching strength, physical ataxia (evaluated using the Scale for the Assessment and Rating of Ataxia), motor dysfunction of the upper limbs (evaluated using the Disabilities of the Arm, Shoulder and Hand questionnaire), and vision quality (evaluated using the National Eye Institute Visual Function Questionnaire 25).

Results

Of 103 total subjects, 61.2% satisfied the definition of instillation failure. Instillation of the eyedrop other than at the cul-desac (76.2%) was the most frequent reason for failure, followed by contact of the tip of the eyedrop bottle (22.2%) and instillation of the same or more than two eyedrops in a single attempt (11.1%). Advanced age, a shallow cervical spine extension angle, weak pinching strength, poor motor dysfunction of the upper limbs, the degree of ataxia, poor best-corrected visual acuity, and visual field scores were significant risk factors for instillation failure. Vision quality may have some relation to instillation failure.

Conclusion

It is highly recommended that instillation failure be routinely investigated even among patients with adequate experience using eyedrops and that correct therapies are chosen in a patient-based fashion.

Topical preservative-free ophthalmic treatments: an unmet clinical need

Introduction: The main role of preservatives in eyedrops is to ensure sterility and microbiological integrity of the drug, and to facilitate the penetration of active compounds into the eye. However, several studies documented significant toxic effects induced by preservatives, especially on the ocular surface. Consequently, most of the ophthalmic medications became progressively available in preservative-free (PF) formulations.Areas covered: We analyzed pre-clinical and clinical studies on PF eyedrops with particular attention to common chronic diseases such as dry eye and glaucoma. We discussed about the pros and cons of using PF eyedrops, in terms of efficacy, safety, and social-economic aspects.Expert opinion: There are still unresolved issues that make hard for PF medications to definitively conquer the drug market. Despite robust pre-clinical evidences of less toxicity, the low number of randomized clinical trials does not permit to state that PF eyedrops have, in clinical practice, a similar efficacy or a higher safety compared to preserved forms. These aspects limit their use to chronic diseases requiring long-term therapies with multiple daily instillations, especially in the presence of concomitant ophthalmic diseases that expose to a risk of ocular surface worsening.