Do Contact Lenses Really “Support Your Vision”?

Contact lenses have been frequently used as an alternative to glasses. Compared to the heavy-framed glasses in front of one’s eyes (optic glasses), thin plastic discs on the eye (contact lenses) help correct refractive errors in both myopic and hypermetropic users.

The lens’ shape and power can be tailored to the user’s sight. A concave lens can be used to decrease myopia by reducing light refraction and increasing focal length so that the image is formed on the retina (1)  (Figure 1). Alternatively, a convex lens can be used to limit hypermetropia in an opposing mechanism to concave lenses (1) (Figure 1).

Figure 1, An illustration of myopia and hyperopia and how adding lens of different shapes in front of the eye can be used to alter the refraction of light and correct each impairment in vision (10)

Besides supporting sight, which both types of lenses can do, contact lenses confer some advantages that make them preferable to glasses. Unlike glasses, contact lenses are less likely to fall off and “break” due to their lighter weight and non-fragile nature (2,3). Subsequently, lenses are much more convenient when exercising or moving excessively. The risk of them falling is much lower than glasses in either situation. (2). Moreover, contact lenses are not affected by the changes in temperature or weather(3).  While glasses fog up when changing between colder and warmer environments, this isn’t the case with contact lenses. (3). This problem has especially been highlighted during the pandemic when glasses’ users have to wear a face mask as well (breathing into the mask sometimes causes the glasses to fog up). Socially, contact lenses are less obvious (if at all). Hence, the person can conceal their visual impairment (which some might view as a disability and cause stigma) (4). Likewise, wearing glasses has been correlated with a greater risk of bullying (especially as a child) (4,5). 

On the other hand, Contact lenses are associated with a greater risk of infection, irritation, and scleral dryness.  Contact Lenses absorb tears and limit their production by decreasing oxygen flow (6,7). This can lead to Contact lens-induced dry eye (CLD),, which can result in redness, soreness, and itchiness of the eyes (6). Tears reduce the risk of eye infections by washing away any foreign bodies on the eye. The reduction in tears and compromise in corneal epithelial integrity associated with contact lenses promote the adherence of pathogens to the cornea (6). This puts contact lens users at a greater risk of keratitis (Figure 2)(6, 8, 9). Conjunctivitis (Figure 3) is also linked to wearing contact lenses. If inappropriately cleaned, bacteria can colonize the lens (10,11). As the lens is placed directly on the eye (bypassing 2 major physical pathogen barriers- eyelids and eyelashes), bacteria are more likely to spread and infect the conjunctiva(10). These are only two of many infections caused by the inappropriate use and care of contact lenses. Eye infections can have effects that range from pain and discomfort to blindness (6,10,11).

Figure 2, Keratitis - this is when there is inflammation of the cornea, shown by the redness of the eye(8)

Figure 3, Conjunctivitis - this is inflammation of the conjunctiva, the outermost layer of the eye (10)

To harvest the advantages of wearing contact lenses and avoid complications, users need to ensure their contact lenses are cared for appropriately and regularly. Regular cleansing of the contact lenses and replacement at appropriate intervals according to indication is crucial (12).  Additionally, avoid dry eyes by frequently hydrating their eyes (via lubricating eye drops) and limiting the time contact lenses are worn (by taking them off at intervals) (11,12). By maintaining lenses appropriately, I think users will be able to make the best of both worlds.

Written by Maiar Elhariry

References:

1. https://global.canon/en/technology/s_labo/light/003/02.html

2. https://www.aoa.org/healthy-eyes/vision-and-vision-correction/types-of-contact-lenses?sso=y

3. https://www.specsavers.co.uk/contact-lenses/monthly-contact-lenses

4. https://nces.ed.gov/pubs2019/2019054.pdf

5. https://www.reviewofoptometry.com/article/kids-who-wear-glasses-are-bully-magnets

6. https://www.specsavers.co.uk/contact-lenses/eye-conditions-symptoms/contact-lenses-for-dry-eyes#:~:text=Contacts%20can%20cause%20dry%20eye,the%20outer%20and%20inner%20layers

7. https://www.visiondirect.co.uk/eye-care-centre/dry-eyes-and-contact-lenses 

8. https://www.researchgate.net/publication/224830712_Bacterial_Keratitis_-_Causes_Symptoms_and_Treatment

9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3972779/

10. https://www.willseye.org/corneal-complications-contact-lenses/

11. https://www.specsavers.co.uk/contact-lenses/eye-conditions-symptoms/eye-infections-acanthemoeba-keratitis

12. https://www.specsavers.co.uk/contact-lenses/wearing-contact-lenses