Diseases and Disorders of the Cornea: Part II

By Diana Chu, OD

The cornea is vulnerable to a range of diseases that can compromise both vision and comfort. Those most commonly seen by optometrists in clinic are keratoconus; Fuchs endothelial dystrophy; Herpes simplex virus and Herpes zoster; dry eye disease (DED); myopia; neurotrophic keratitis; and corneal abrasions, corneal foreign bodies, and recurrent corneal erosions. Most of these conditions are progressive; therefore, if left untreated, they can result in some form of scarring, nerve damage, or even changes in vision. Thus, we need to have more medical vigilance about the disease state of the cornea. This means paying attention to the health of the cornea, not just managing a patient’s sight and vision. Part two of this article by Diana Chu, OD, reviews DED; myopia; neurotrophic keratitis; and corneal abrasions, corneal foreign bodies, and recurrent corneal erosions, including any noteworthy points about their signs, symptoms, differentials, and treatment options.

DRY EYE DISEASE
Every optometrist should know that DED is a multifactorial condition involving a loss of tear film homeostasis and ocular symptoms, and that it can be caused by inadequate tear production, excessive evaporation, or inflammation.¹ All doctors should be screening patients for DED because it’s a big contributor to vision fluctuation.

MYOPIA
Myopia occurs when the eye is too long or the cornea is too curved, causing light entering the eye to focus incorrectly and make distant objects look blurry. Individuals with several myopia-prone genes have a higher risk of becoming nearsighted, as do children with one or both parents who are myopic.² Myopia management strategies might include lifestyle and environmental factors, whereas myopia control focuses more on methods to slow down the progression of the condition. Depending on patient age, treatments include the use of myopia control contact lenses (eg, orthokeratology lenses, multifocal contact lenses, soft contact lenses), eyeglasses, laser procedures (eg, LASIK or photorefractive keratectomy), and vision therapy.

NEUROTROPHIC KERATITIS
Neurotrophic keratitis (NK) is a reduction or loss of corneal sensation. This type of damage could also be related to Herpes zoster, Herpes simplex, recurrent corneal abrasions, or DED.^3,4 If the fundamental reason for the loss of corneal sensation is NK, the presentation in early stages (stage 1 and stage 2) can look just like any of the aforementioned conditions.

The best way to differentiate NK from the others is to perform corneal sensitivity testing.

ABRASIONS, FOREIGN BODIES, AND RECURRENT CORNEAL EROSIONS
When treating corneal abrasions, corneal foreign bodies, and recurrent corneal erosions, it’s important to know the scope of the legislative law in your state, because although all optometrists are trained to remove corneal foreign bodies, some are not permitted by law to remove them.

KEEPING BUSY WITH CORNEAL DISEASE
Managing the patients in my clinic, we have a strong working knowledge of medical conditions that affect the cornea. Many times, when we identify a corneal condition, it raises suspicion about an autoimmune disease, and if a patient is unaware they have an autoimmune disease, we encourage them to see a rheumatologist. If the patient does know they have an autoimmune condition, then it’s important to monitor their cornea and educate them on how their condition or disease can affect it. We can’t forget about these other systemic and autoimmune conditions, such as rheumatoid arthritis or lupus, which can cause inflammation of the cornea and conditions such as scleritis or keratitis.

COMPREHENSIVE CARE FOR CORNEAL HEALTH
Patients with corneal disease who also want refractive vision correction beyond eyeglasses have options (eg, specialty lenses). Lifestyle modifications, such as limiting exposure to ultraviolet light, staying hydrated, maintaining proper lid hygiene, and not smoking, can help keep the cornea and ocular surface healthy.

References:

1. The definition and classification of dry eye disease: report of the Definition and Classification Subcommittee of the International Dry Eye Workshop (2007). Ocul Surf. 2007;5(2):75-92.
2. Myopia (nearsightedness). American Optometric Association. Accessed February 24, 2025. www.aoa.org/healthy-eyes/eye-and-vision-conditions/myopia?sso=y
3. Meyer JJ, Liu K, McGhee CNJ, Danesh-Meyer HV, Niederer RL. Neurotrophic keratopathy after Herpes Zoster ophthalmicus. Cornea. 2022;41(11):1433-1436.
4. Feroze KB, Patel BC. Neurotrophic keratitis. StatPearls [Internet]. August 8, 2023. Accessed March 7, 2025. www.ncbi.nlm.nih.gov/books/NBK431106/

• Optometrist, Washington Eye Institute, Washington, DC
• dianachuod@gmail.com
• Financial disclosure: None

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