An estimated 140 million people worldwide wear contact lenses to correct refractive errors.
They are classified as soft and rigid, but the most commonly used are the soft ones, while the rigid ones are usually reserved for correcting irregular astigmatisms.
Although they are a good alternative to glasses, if not used correctly, they can cause complications. The most common is dry eye syndrome, which accounts for approximately 30% of ophthalmology visits.
Complications from wearing contact lenses
The use of contact lenses can cause various complications, which can be classified as infectious and non-infectious:
Non-infectious complications
- Discomfort and dryness: Up to 50% of wearers experience discomfort and dry eyes due to soft contact lens use. Symptoms can range from mild discomfort to intense pain that can even lead to lens intolerance. Discomfort is the most common reason for discontinuing wear, accounting for 30% of such discontinuations. The reason is that contact lenses reduce the stability of the tear film and increase evaporation. Factors that contribute to this include the type of contact lenses (soft lenses tend to cause more dry eye problems than rigid ones), prolonged wear, low relative humidity, advanced age, certain medications, and the presence of concomitant diseases, among other causes. To prevent these symptoms, it is essential to frequently lubricate the ocular surface with artificial tears.
- Corneal hypoxia: The cornea is nourished, oxygenated, and eliminates metabolic products through tears. When contact lenses interfere with these functions, corneal hypoxia can occur, i.e., a decrease in oxygen supply to the cornea, leading to limbal hyperemia, edema, and corneal thinning. When signs of corneal hypoxia appear, a good option is to change contact lenses to ones that offer greater oxygen permeability.
- Sterile infiltrates: Contact lenses, being a foreign body in contact mainly with the cornea, can promote the appearance of ulcers or erosions whose symptoms, in addition to the sensation of a foreign body in the eye, can be accompanied by discomfort, photophobia and continuous tearing, as well as acute red eye, an inflammatory reaction of the cornea and conjunctiva that usually appears when the user exceeds the recommended usage time or falls asleep with the lenses in.
- Superior arcuate keratopathy : This condition usually presents asymptomatically, although it can also cause a foreign body sensation or irritation in a small percentage of patients. It is more common in men, people over 40 years of age, curved corneas, hypoxia, dehydration, silicone lenses, and mechanical friction.
- Toxic reactions: These are usually caused by preservatives in disinfectant solutions, such as thiomersal, benzalkonium chloride, or hydrogen peroxide. They generally produce delayed hypersensitivity reactions and limbic cell deficiency.
- Superior limbic keratoconjunctivitis: Characterized by inflammation of the upper conjunctiva and cornea. Its most common symptoms are foreign body sensation, flushing, photophobia, and mucoid discharge.
- Giant papillary conjunctivitis: This is a very common complication, the causes of which may include mechanical etiology and a history of atopy. Symptoms include a burning sensation, hyperemia, discharge, and decreased tolerance to contact lenses.
Infectious complications
Infectious keratitis: It is estimated that more than 50% of contact lens cases and up to 30% of contact lens solutions are contaminated. Contact with contaminated water, storing contact lenses in water, handling them with wet hands, or rinsing the case with tap water can cause infectious keratitis. Its main symptoms are usually pain, photophobia, and decreased visual acuity. Although rare, in 15% of cases, the patient may lose two or more lines of vision. Therefore, early diagnosis and treatment are essential.
Dry eye syndrome and its symptoms
As its name suggests, it is characterized by excessive dryness of the eye caused by a lack of natural tears. Also known as dry eye, tear duct dysfunction, keratoconjunctivitis sicca, dry keratitis, or xerophthalmia, the most widely accepted definition of this syndrome describes it as “a multifactorial disease of the tears and ocular surface” (International Dry Eye Workshop, 2007).
This syndrome has the following symptoms, which, as the term “multifactorial” in its definition indicates, can be very varied:
- Discomfort.
- Impaired vision.
- Tear film instability.
- Possibility of damage to the ocular surface.
- Increased tear osmolarity.
- Inflammation of the ocular surface.
Between 20% and 30% of the population suffers from dry eye, although it is more common in people over 45 years of age and in women.
Dry eye can be intermittent or chronic, and can be mild, moderate, or severe. It is currently classified into two main groups:
- Due to a deficiency in water production:
- Primary and secondary Sjögren’s syndrome.
- Dry eye syndrome without associated autoimmune disease.
- Due to excessive evaporation of the tear film (dry eye), the most common causes of which are:
- Meibomian gland disease (alteration in the lipid layer of the tear film).
- Blinking disorders (7th nerve palsy, proptosis due to Graves-Basedow disease).
- Use of contact lenses.
Consequences of dry eye
The onset of dry eye syndrome has consequences for the daily lives of those who suffer from it, and particularly affects their work environment:
- Alteration in vision quality and contrast sensitivity, which interferes with habits such as reading, using screens, driving, or working.
- Impact on quality of life due to chronic discomfort.
- Intolerance to the use of contact lenses.
- Increased risk of eye infections.
- Impact on healing after eye surgeries.
- Increase in sick leave and lower performance.
Tips to avoid dry eyes from contact lenses
Several measures and precautions should be taken to prevent dry eye syndrome when it’s caused by contact lenses. These five stand out:
- Replacing contact lenses
It is very important to follow the recommended guidelines for replacing contact lenses. It’s also important to remember to change your contact lens case regularly, every one to three months. It is estimated that 62% of infectious keratitis cases are caused by not following these basic precautions.
- Respect the recommended usage time
Avoiding extended wear regimens, such as sleeping in contact lenses or wearing ones that are too tight, prevents the development of sterile inflammatory infiltrates and corneal hypoxia.
- Hand hygiene
To avoid infections, it is crucial to maintain good hand hygiene and dry hands thoroughly before handling contact lenses.
- Avoid contact with water
Contact lenses should be avoided in contact with water. This means avoiding bathing with them or storing them in containers filled with water.
- Use artificial tears
To maintain proper eye hydration and lubrication, you should get used to using preservative-free artificial tears regularly, several times a day.
In addition, tobacco should be avoided, as it increases the likelihood of developing infiltrates, both inflammatory and infectious.
It is also advisable to avoid the use of disinfectant solutions such as thiomersal, especially in atopic patients, who are more prone to toxic reactions. If contact lenses are stored with hydrogen peroxide-based solutions, they should be thoroughly rinsed before use. Disinfectants with acanthamoebicidal agents (polyhexamethylene biguanide or hydrogen peroxide-based systems) should also be used.
Other measures to treat dry eyes
Since other factors besides contact lens use can cause dry eyes, other general complementary, non-pharmacological measures are recommended for daily routines. These include:
- Ventilate rooms and, if necessary, use humidifiers to prevent dryness. Avoid excessive use of heating and air conditioning.
- Force blinking in situations requiring visual concentration, such as driving, reading, or working in front of a screen.
- Maintain an appropriate reading distance and prioritize natural light.
- Maintain adequate backlighting for any digital device. Position yourself comfortably in front of the computer screen, about 15° below your eyes.
- Wear protective goggles to protect against dry eyes.
- Drink more water and fluids, as well as follow a diet rich in vegetables, fruits, and fish.
In short, while contact lenses are a safe option, basic hygiene measures must be followed, and it is important to understand their care, risks, side effects, and therapeutic management. It is also important to re-educate people who suffer or have suffered any complications.