Dry Eye Syndrome and Contact Lenses

Introduction

Dry eye syndrome (DES), is also sometimes referred to as keratoconjunctivitis sicca (KCS) or keratitis sicca and is a very common condition affecting the eyes of roughly 50% of adults.^1,2 One of the key components to keeping a healthy eye is tears. During blinking, the tears produced by the glands located above our eyes, coat the cornea allowing a smooth and clear surface of the eye. This is known as a tear film and is composed of an oil layer, water layer and mucus layer which all play essential roles in keeping our eyes moist and ensuring a clear vision.¹

There are about 140 million people around the world that wear contact lenses and, approximately 35-50% of them, experience discomfort and dryness of the eyes.³ By wearing contact lenses, the thin film sits on the cornea and limits oxygen availability so the eyes are not able to form natural tears resulting in dry eyes. Therefore it is advisable not to wear contact lenses for long periods of time, and use eye drops if necessary to keep the eyes moist.⁴

Causes and symptoms of dry eye syndrome

There are many possible causes that can lead to dry eyes and make certain people more prone to it. Both genetics and environmental factors play big roles in dry eye syndrome. Some studies have suggested that dry eye syndrome can be inherited from previous generations, especially in people of Hispanic and Asian ethnicities.¹ Medical conditions, which can be due to genetics, also play a role in the development of dry eyes. Some of the most commonly associated medical conditions include rheumatoid arthritis, diabetes, and thyroid problems.¹ In addition, dry eye syndrome is more prone in adults and females compared to males.⁴

Whilst genetics is hard to control and take into account when managing dry eye syndrome, there are many environmental factors that can be avoided or taken into account when wearing contact lenses.¹ Some of the most common environmental causes of dry syndrome are:

• Computer screens, especially when reading for long periods of time, lead to dry eyes as they can reduce the number of times a person blinks. The blue light emitted from computer screens and other electronics can also contribute to dry eyes⁵
• Medications like antihistamines, decongestants, blood pressure medications, and antidepressants can contribute to dry eyes as they can stop or reduce overall tear production¹ 
• Climate can also play a role in contributing to dry eye syndrome. Environmental conditions like wind, smoke and dry climates are more prone to cause dry eyes as they can promote the evaporation of tears¹
• Smoking and Alcohol have been linked with many eye conditions including dry eyes⁶

Symptoms of DES include eye redness, irritation, and blurred vision.The most common symptoms of dry eyes are

• Dryness and irritation of the eyes
• Burning or stinging sensation in the eyes
• Sensitivity to light
• Blurred vision
• Eye fatigue
• Excessive tearing
• Redness of the eyes ⁴

The relationship between contact lenses and dry eye syndrome

In general, contact lenses are not supposed to cause any physical pain or supposed to hurt. However, they may cause slight discomfort and exacerbate dry eye syndrome. Contact lenses are placed on the cornea of the eye and divide the tear film into two layers reducing the tear flow, also known as “tear exchange”.³ Wearing contact lenses also limits the amount of oxygen available for the cornea hence reducing tear production. In addition, the contact lenses which are worn normally require the tears produced by the eyes to remain soft and flexible. Therefore the contact lenses, especially those which are not properly fitted or are of bad quality, can absorb the tear film resulting in fewer tears coating the eyes.⁷ 

The material that the contact lens is made from is very important. There are two main types of contact lenses; soft and rigid. The rigid contact lenses are made of rigid gas-permeable plastic, allowing them to stay hard and stiff. In contrast, soft contact lenses are made of silicone hydrogel, which contributes to their flexibility. Both types of contact lenses work well and allow people to see regardless if they are farsighted or nearsighted. However, depending on the circumstance and person, there are advantages and disadvantages of using soft or rigid contact lenses. In general, rigid contact lenses are more durable and advised for people with unique eye shapes. However, this also means that they are not as comfortable compared to soft contact lenses, which are more flexible.⁸ 

For people with dry eye syndrome, it is recommended to use scleral lenses, which are a form of hard contact lenses. This is because they are designed not to touch the cornea, hence minimising irritation, one of the dry eye disease symptoms. In addition, one of the main things that soft contact lenses do is absorb the tears, allowing them to remain flexible. Scleral lenses on the other hand provide the moisture between the cornea and the lens and also do not absorb as much water content, making them perfect for people with dry eye syndrome.⁹

Managing dry eye syndrome with contact lenses

Many measures and precautions may be taken when wearing contact lenses to help manage dry eye syndrome, beginning with selecting the correct contact lens. There are many types of contact lenses available, therefore it is important to choose the right one, based on the severity of the dry eye syndrome.¹⁰ When making a decision, it is critical to evaluate the lens material, lens water content, and lens size, as well as consult with an eye specialist. 

It is crucial to care for your contact lenses and maintain good hygiene. Some basic tips when handling contact lenses include:

• Use good hand hygiene when handling contact lenses by washing your hands
• Avoid sleeping with contact lenses 
• Change the contact lens solution daily for good disinfection
• Wear the contact lenses according to the recommended time 
• Avoid wearing contact lenses for long periods. Not wearing contact lenses for a few hours daily is advisable to allow the eyes to breathe
• Moistening the eyes before inserting the contact lenses¹¹

In addition, to maintain good hygiene, it is important to have regular checkups with an eye doctor. Typically, contact lens prescriptions include expiry dates, making them difficult to purchase after they expire. Check-ups with your optometrist are recommended before your prescription expires to ensure your vision is clear and to clarify any concerns you may have about wearing contacts. This is very important as your eye doctor will be able to check if the current contact lenses are causing any damage to the cornea or change your prescription.¹²

Treatments for dry eye syndrome

Depending on the severity of the dry eye, the recommended treatments vary. Some of the most common suggested treatments for dry eyes include over-the-counter and prescription treatments like artificial tears and anti-inflammatory medications. Over-the-counter eye drops are the most common treatments given for mild DES as they can be obtained without a prescription.¹³ Eye drops, also known as artificial tears, are very efficient as they increase the moisture of the eye and work extremely well for some people. However, in some cases prescribed medicines are necessary. One of the commonly prescribed medications for DES is the anti-inflammatory cyclosporine, also known as Restasis, as it helps increase tear production and decrease the risk of damage to the cornea. In more severe cases, other medications may be prescribed like corticosteroid eye drops and cholinergic.¹⁰

If none of these treatments works, there are more advanced treatments that may be suggested by your eye doctor, including lacrimal plugs and surgery. Lacrimal plugs are plugs that may be used by your eye doctor to essentially block the drainage holes found in the corner of your eyes. This is a painless and reversible procedure that helps with DES by slowing down the tear loss. If lacrimal plugs do not work, the eye doctor may propose surgery to permanently plug the drainage pores if the case is severe.¹⁰ Fixing the eyelids is another extremely rare procedure that can be undertaken. In some situations, the lower eyelids may become lax, resulting in a rapid loss of tears. This procedure corrects the condition, allowing tears to remain in the eye.¹³

Summary

To conclude, DES is a common problem faced by many contact lens wearers in which people may suffer discomfort due to a lack of tears in the eye. Luckily, there are solutions for this problem such as finding the right contact lenses, maintaining good hygiene and allowing the eye to breathe. If these solutions do not work, some treatments can be considered depending on the severity of the dry eyes.