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A recent study explored the potential of a novel ophthalmic emulsion in dry eye subjects dosed twice daily for 2 weeks.
Take-home: A recent study explored the potential of a novel ophthalmic emulsion in dry eye subjects dosed twice daily for 2 weeks.
By Marguerite B. McDonald, MD, FACS, Special to Ophthalmology Times
Rockville Centre, NY-No question about it: Dry eye may be one of the most challenging ocular diseases to tackle, and one for which eye-care professionals (ECPs) have sought relief from for some time.
In fact, ancient medicinal recipes for dry eye referencing eye pastes with exotic elemental ingredients, such as antimony, copper, and manganese, were thought to be written between 1553 and 1550 B.C.1
With only one FDA-approved prescription treatment, dry eye sufferers are left to wade through an assortment of over-the-counter (OTC) artificial drops, lubricants, and gels that offer symptomatic relief.
Though dry eye estimates vary from study to study, the number of dry eye sufferers will undoubtedly grow in the next 10 to 20 years as the general population ages. As the most common choice for relief, the artificial tear market is projected to reach $2 billion globally by 2018. There is an increasing demand for OTC and prescription products that treat dry eye.
In eye drop formulations of any kind, one of the most significant challenges is that the product is rapidly eliminated from the ocular surface following instillation due to a variety of ocular barriers (reflex tearing, blinking, or punctal drainage). These barriers mean that any topical preparation is faced with significant challenges with regard to residence time on the ocular surface. Addressing these challenges begins with developing a formulation that remains longer on the ocular surface.
Lipid emulsion-based tears contain water-soluble components, which replicate natural tear components, and a lipid emulsion-fine particles of lipid aggregates that surround and encapsulate, or coat, the less water-soluble additives (e.g., drugs, vitamins) in the tears. Because lipids are one of the main building blocks of outer cell membranes, lipid emulsion-based tears can pass through the cell surface easily, carrying any attached additives with them, and thereby enhancing the ocular penetration.
Cationic oil-in-water emulsions offer an additional advantage over anionic oil-in-water emulsions in that an electrostatic interaction occurs with the negatively charged ocular surface epithelium.
This interaction increases the residence time on the ocular surface, thereby enhancing the protection and restoration of a healthy tear film and corneal epithelium.
One ophthalmic emulsion (Retaine, OCuSOFT) is currently the only product in the United States that employs this unique cationic formulation. The product is preservative-free and contains Novasorb, a proprietary cationic oil-in-water nanoemulsion technology with novel bioadhesive properties.
Additionally, the product is a hypo-osmotic agent and can counter balance the hyperosmotic tears of patients with dry eye.
A recent study conducted by Ora Inc., Andover, MA, explored the potential of this ophthalmic emulsion in dry eye subjects dosed twice daily (b.i.d.) for 2 weeks. The outcomes of the study suggest that the product has statistically and clinically significant benefits in terms of reducing both the signs and symptoms of dry eye, ultimately improving patients’ quality of life (QoL).
In this phase IV, two-visit study, 42 subjects received 1 to 2 drops of the product b.i.d. for 2 weeks. Screening procedures identified subjects who had a history of dry eye and moderate to severe symptoms. Study subjects received one dose at the first visit and were instructed to dose b.i.d.-once in the morning and once in the evening before bed-up through the morning of the second visit.
Subjects were also dispensed a diary to score their symptoms prior to each self-administered instillation. Primary efficacy measures were TFBUT and corneal fluorescein staining, whereas secondary efficacy measures included ocular discomfort, ocular symptoms, QoL, conjunctival redness, interblink interval (IBI), tear film stability, corrected visual acuity degradation between blinks, and drop comfort.
In recent years a considerable number of advancements have occurred in the techniques and equipment used to evaluate patients with dry eye.
One of the key features of dry eye examined during the study was tear film instability. A video-based technology (OPI2.0, Ora Inc.)-designed to measure the percent of the cornea that is exposed when the tear film becomes unstable and breaks up-was used during the study.
Across the entire subject population, a 40% decrease in corneal exposure was seen. This increased coverage of the cornea may be due in part to the unique electrostatic reaction of the positively charged emulsion and the negatively charged ocular surface.
At the 2-week visit, subjects had significantly less corneal fluorescein staining in the superior (p = 0.002), central (p = 0.017), corneal sum (p = 0.011), and total eye (cornea and conjunctiva combined) regions (p = 0.038). Of particular interest is the reduction in central staining, which has previously been directly linked to visual function performance.2
The effect of dry eye on visual function was further explored by testing corrected visual acuity (CVA) degradation between blinks using the Interblink Interval Visual Acuity Decay Test (IVAD). Interestingly, study subjects demonstrated a 41% improvement in time at CVA from the first visit to the second. As expected in light of the link between central corneal staining and visual function, the IVAD results correlated with central staining.
For most ECPs, a tear that demonstrates an improvement in symptoms and in patients’ QoL is the optimal choice. Significant reductions were observed in several ocular symptoms, including discomfort (p = 0.0017), dryness (p = 0.001), and grittiness (p = 0.0217).
Subjects also reported a significant improvement in ocular discomfort when they worked at a computer at night (p = 0.044). QoL scores also decreased for reading at night, watching television at night, and driving at night.
Overall, the ophthalmic emulsion provided relief from both the signs and symptoms of dry eye sufferers after only 2 weeks of treatment, as well as an immediate-onset improvement in tear film stability.
Additionally, the product was well-tolerated and provided simultaneous symptomatic relief and QoL improvements. While ophthalmologists appreciate the improvements seen on the ocular surface in the clinic or office, patients are most grateful for the relief that they can feel in their eyes during daily activities.
The unique electrostatic reaction between the product and the ocular surface likely plays a substantial role in its success with patients with dry eye. Though this disease has challenged researchers for years, this OTC treatment appears to be breaking positive ground in the dry eye space.
1. Hirschberg J. The History of Ophthalmology, Volume I: Antiquity. Translated by F. C. Blodi. Bonn, West Germany: Verlag J.P. Wayenborgh, 1982.
2. Lemp MA. Advances in understanding and managing dry eye disease. Am J Ophthalmol. 2008;146:350-356.
Marguerite B. McDonald, MD, FACS, is a cornea/refractive specialist with Ophthalmic Consultants of Long Island, Rockville Centre, NY, a clinical professor of ophthalmology at the NYU School of Medicine, and an adjunct clinical professor of ophthalmology at the Tulane University Health Sciences Center, New Orleans. She acknowledged no financial interest in the products or companies mentioned herein. Dr. McDonald may be reached at 516/593-7709 or firstname.lastname@example.org.