Navigating the vast array of eye drops available for treating dry eyes can be overwhelming, with numerous brands and products containing various ingredients. Understanding the composition of these eye drops is crucial for finding the most effective solution for your specific needs. In this article, we’ll explore the key ingredients found in artificial tears and provide guidance on what to look for when selecting the right product.
Preservatives: A Controversial Topic
The use of preservatives in eye drops is a topic of debate. While they are added for their antibacterial properties to maintain sterility, preservatives can also irritate the cornea and conjunctiva, potentially causing long-term damage to already sensitive dry eyes. Some preservatives may even destabilize the tear film, exacerbating dry eye symptoms.1
For those using eye drops for extended periods or individuals with severe dry eye, preservative-free artificial tears are often recommended. Preservatives are also incompatible with contact lenses, as the fluid can become trapped between the lens and the cornea, causing irritation.2
Common preservatives include cetrimide, benzalkonium chloride, polyhexanide (PHMB), polidronium chloride, sodium chlorite, and edetate disodium (EDTA). Always read the ingredient label to determine if your eye drops contain preservatives. Preservative-free eye drops are usually packaged in special bottles or single-use vials to maintain sterility.
Buffers for pH Balance
Eye drops contain buffers to maintain a stable pH. The most common buffers are phosphate or citrate. However, phosphate buffers can lead to calcification (accumulation of calcium salts) on an already irritated cornea, causing impaired vision.3 If you have any pre-existing corneal damage, choose a product without phosphate buffers.
Tear Film-Stabilizing Polymers
Polymers are added to artificial tears to stabilize the tear film, with their primary difference being viscosity. Higher viscosity eye drops remain in the eye longer, making them suitable for severe dry eyes. However, they may temporarily blur vision.
Mucus Layer-Stabilizing Polymers
The inner mucus layer of the tear film protects the cornea, facilitates eyelid movement, guards against bacteria and other germs, and helps the tear film spread evenly and remain stable. Common mucus layer-stabilizing polymers include:
Povidone and PVA
Povidone and polyvinyl alcohol (PVA) create low-viscosity solutions suitable for mild dry eye symptoms.4,5 FreshKote preservative-free lubricating eye drops are an example.6
Cellulose Derivatives and Carbomers
More viscous than povidone and PVA, cellulose derivatives and carbomers remain in the eye longer and are suitable for moderate symptoms.7,8 GenTeal Tears preservative-free lubricant eye drops contain the cellulose derivative hypromellose.9
Hyaluronic Acid
Usually added as sodium hyaluronate, hyaluronic acid is naturally produced in the body and found in the eye, making it well-tolerated. It binds to water, creating high viscosity, and promotes corneal regeneration.10,11 High-concentration hyaluronic acid products are suitable for severe symptoms, such as Hylo-Forte preservative-free lubricating eye drops.12
Guaraprolose
A guar gum derivative, guaraprolose is fluid in the bottle but becomes viscous upon contact with the eye, making it suitable for moderate to severe symptoms.13 Systane Ultra preservative-free lubricant eye drops contain guaraprolose.14
While some eye drops contain multiple polymers for increased efficacy, trying a single-polymer product first may be prudent, as any ingredient can cause intolerance.
Lipid Layer-Stabilizing Agents
The outer lipid layer prevents tear evaporation, and its instability is a common cause of dry eyes. Lipid-containing artificial tears can be an effective treatment, especially for those with meibomian gland dysfunction.15 These eye drops may also contain mucus layer-stabilizing polymers. Soothe XP Emollient lubricating eye drops, for example, contain mineral oil to stabilize the lipid layer.16
Additional Ingredients
Several other ingredients may be found in artificial tears, each serving a specific purpose:
- Dexpanthenol: A vitamin B5 derivative that promotes corneal and conjunctival regeneration and hydrates the eye. However, studies on its efficacy for treating dry eyes are inconclusive, and it may cause side effects like itching and burning in some cases.17
- Glycerin, Propylene Glycol, and Polyethylene Glycol: These ingredients help polymers remain in the eye longer.18
- Eyebright (Euphrasy): A plant extract with potential antibacterial and anti-inflammatory properties, though its therapeutic benefit for dry eyes is unclear.19
- Vitamin A: Essential for eye health, mild vitamin A deficiency can contribute to dry eyes. Vitamin A-containing eye drops can support dry eye therapy.20,21
- Anti-inflammatory ingredients: Dry eyes trigger inflammation, which in turn causes more dryness. Anti-inflammatory agents like cyclosporine A and corticosteroids can break this cycle.22,23,24,25
- Antibacterial and antiviral ingredients: When dry eyes result from an infection, antibiotics or antiviral agents can help clear the underlying cause.26,27,28
Finding the Right Artificial Tears for Your Needs
With the vast array of eye drops available, each containing different ingredients and combinations, finding the most effective and well-tolerated product for your individual needs may require some trial and error. By understanding the various components of artificial tears and their specific functions, you can make a more informed decision when selecting an eye drop to manage your dry eye symptoms.
If your dry eye symptoms persist or worsen despite using artificial tears, consult your eye care professional for a comprehensive evaluation and personalized treatment plan.
Also, if you typically have problems while working at the computer, try Blinkr! It is a PC app that monitors your blinks using your webcam and gives you interactive blink reminders as necessary.
References
1. Messmer EM. The Pathophysiology, Diagnosis, and Treatment of Dry Eye Disease. Deutsches Aerzteblatt Online. January 2015. doi:10.3238/arztebl.2015.0071
2. Pflugfelder SC, de Paiva CS. The Pathophysiology of Dry Eye Disease. Ophthalmology. 2017;124(11):S4-S13. doi:10.1016/j.ophtha.2017.07.010
3. Dry Eye. https://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/dry-eye. Accessed October 25, 2019.
4. Bentivoglio AR, Bressman SB, Cassetta E, Carretta D, Tonali P, Albanese A. Analysis of blink rate patterns in normal subjects. Movement Disorders. 1997;12(6):1028-1034. doi:10.1002/mds.870120629
5. Freudenthaler N, Neuf H, Kadner G, Schlote T. Characteristics of spontaneous eyeblink activity during video display terminal use in healthy volunteers. Graefe’s Archive for Clinical and Experimental Ophthalmology. 2003;241(11):914-920. doi:10.1007/s00417-003-0786-6
6. Kojima T. Contact Lens-Associated Dry Eye Disease: Recent Advances Worldwide and in Japan. Investigative Opthalmology & Visual Science. 2018;59(14):DES102. doi:10.1167/iovs.17-23685
7. Fraunfelder FT, Sciubba JJ, Mathers WD. The Role of Medications in Causing Dry Eye. Journal of Ophthalmology. 2012;2012:1-8. doi:10.1155/2012/285851
8. Lemp MA, Crews LA, Bron AJ, Foulks GN, Sullivan BD. Distribution of Aqueous-Deficient and Evaporative Dry Eye in a Clinic-Based Patient Cohort. Cornea. 2012;31(5):472-478. doi:10.1097/ICO.0b013e318225415a
9. Tong L, Chaurasia SS, Mehta JS, Beuerman RW. Screening for Meibomian Gland Disease: Its Relation to Dry Eye Subtypes and Symptoms in a Tertiary Referral Clinic in Singapore. Investigative Opthalmology & Visual Science. 2010;51(7):3449. doi:10.1167/iovs.09-4445
10. Zhang X, Zhao L, Deng S, Sun X, Wang N. Dry Eye Syndrome in Patients with Diabetes Mellitus: Prevalence, Etiology, and Clinical Characteristics. Journal of Ophthalmology. 2016;2016:1-7. doi:10.1155/2016/8201053
11. Akpek EK, Klimava A, Thorne JE, Martin D, Lekhanont K, Ostrovsky A. Evaluation of Patients With Dry Eye for Presence of Underlying Sjögren Syndrome. Cornea. 2009;28(5):493-497. doi:10.1097/ICO.0b013e31818d3846
12. Kan E, Kılıçkan E, Ecemiş G, Beyazyildiz E, Çolak R. Presence of Dry Eye in Patients with Hashimoto’s Thyroiditis. Journal of Ophthalmology. 2014;2014:1-4. doi:10.1155/2014/754923
13. Schaumberg DA. Hormone Replacement Therapy and Dry Eye Syndrome. JAMA. 2001;286(17):2114. doi:10.1001/jama.286.17.2114
14. Evinger C, Bao J-B, Powers AS, et al. Dry eye, blinking, and blepharospasm. Movement Disorders. 2002;17(S2):S75-S78. doi:10.1002/mds.10065
15. Sharma A, Hindman HB. Aging: A Predisposition to Dry Eyes. Journal of Ophthalmology. 2014;2014:1-8. doi:10.1155/2014/781683
16. Wardeh R, Besgen V, Sekundo W. Therapy-resistant dry itchy eyes. Journal of Ophthalmic Inflammation and Infection. 2019;9(1):13. doi:10.1186/s12348-019-0178-7
17. Shtein RM. Post-LASIK dry eye. Expert Review of Ophthalmology. 2011;6(5):575-582. doi:10.1586/eop.11.56
18. Barabino S, Rolando M, Nardi M, Bonini S, Aragona P, Traverso CE. The Effect of an Artificial Tear Combining Hyaluronic Acid and Tamarind Seeds Polysaccharide in Patients with Moderate Dry Eye Syndrome: A New Treatment for Dry Eye. European Journal of Ophthalmology. 2014;24(2):173-178. doi:10.5301/ejo.5000355
19. Cohen S, Martin A, Sall K. Evaluation of clinical outcomes in patients with dry eye disease using lubricant eye drops containing polyethylene glycol or carboxymethylcellulose. Clinical Ophthalmology. December 2013:157. doi:10.2147/OPTH.S53822
20. Lee S-Y, Tong L. Lipid-Containing Lubricants for Dry Eye. Optometry and Vision Science. 2012;89(11):1654-1661. doi:10.1097/OPX.0b013e31826f32e0
21. Pflugfelder SC, Maskin SL, Anderson B, et al. A randomized, double-masked, placebo-controlled, multicenter comparison of loteprednol etabonate ophthalmic suspension, 0.5%, and placebo for treatment of keratoconjunctivitis sicca in patients with delayed tear clearance. American Journal of Ophthalmology. 2004;138(3):444-457. doi:10.1016/j.ajo.2004.04.052
22. Marsh P. Topical nonpreserved methylprednisolone therapy for keratoconjunctivitis sicca in Sjögren syndrome. Ophthalmology. 1999;106(4):811-816. doi:10.1016/S0161-6420(99)90171-9
23. Turner K, Pflugfelder SC, Ji Z, Feuer WJ, Stern M, Reis BL. Interleukin-6 Levels in the Conjunctival Epithelium of Patients with Dry Eye Disease Treated with Cyclosporine Ophthalmic Emulsion. Cornea. 2000;19(4):492-496. doi:10.1097/00003226-200007000-00018
24. YOSHIDA A, FUJIHARA T, NAKATA K. Cyclosporin A Increases Tear Fluid Secretion via Release of Sensory Neurotransmitters and Muscarinic Pathway in Mice. Experimental Eye Research. 1999;68(5):541-546. doi:10.1006/exer.1998.0619
25. Olson MC, Korb DR, Greiner J v. Increase in Tear Film Lipid Layer Thickness Following Treatment with Warm Compresses in Patients with Meibomian Gland Dysfunction. Eye & Contact Lens: Science & Clinical Practice. 2003;29(2):96-99. doi:10.1097/01.ICL.0000060998.20142.8D
26. Guillon M, Maissa C, Wong S. Eyelid Margin Modification Associated With Eyelid Hygiene in Anterior Blepharitis and Meibomian Gland Dysfunction. Eye & Contact Lens: Science & Clinical Practice. 2012;38(5):319-325. doi:10.1097/ICL.0b013e318268305a