Long COVID (LC) is an infection-associated chronic condition that occurs after SARS-CoV-2 infection. LC is present for at least 3 months as a continuous, relapsing, and remitting, or progressive disease state that affects one or more organ systems.1
LC is associated with:1
- Development of new or recurrent symptoms and conditions after the symptoms of initial acute COVID-19 illness have resolved.
- Symptoms that can emerge, persist, resolve, and reemerge over varying lengths of time.
- A broad spectrum of physical, social, and psychological consequences.
- Functional limitations that can affect patient wellness and quality of life and may cause disability.
LC occurs more often in people who have had severe COVID-19 illness, but anyone who gets COVID-19 can experience it, including children. Most people with LC report symptoms days after first learning they had COVID-19, but some people who later develop LC do not know when they were infected.1,2
People can be reinfected with SARS-CoV-2 multiple times. Each time a person is infected, they have a risk of developing LC.2,3 LC can present with numerous symptoms, though the most common include fatigue, post-exertional malaise, brain fog, gastrointestinal symptoms, dyspnea, and palpitations.4
Prevalence of long COVID
Prevalence estimates vary widely. One reason for this is the absence of a clear-cut diagnostic biomarker or other definitive diagnostic criterion.
As of 2024, approximately 18% of the total US population has ever experienced LC, with around 38 million Americans having persistent symptoms. In September 2024, 5.3% of the US population reported that they were currently experiencing LC.5
Systemic impact and risk factors
While rates of new cases of LC have decreased since the beginning of the COVID-19 pandemic, LC remains a serious public health concern as millions of US adults and children have been affected.6,7
Although anyone who gets COVID-19 can develop LC, multiple studies have shown that some groups of people are more likely to develop it than others, including:5,6
- Women
- People who are middle-aged
- Hispanic and Latino individuals
- Patients who have experienced more severe COVID-19 illness, especially those who were hospitalized or needed intensive care
- People with underlying health conditions such as:
- Depressive disorder
- Asthma
- COPD
- Obesity
- Diabetes
- Cardiovascular disease
- Chronic kidney disease
Etiologies of LC
LC is a heterogeneous condition and may be attributed to diverse underlying pathophysiologic processes.
Possible etiologies include:8
- Organ damage resulting from the acute phase infection
- Complications from a dysregulated inflammatory state
- Microvascular dysfunction
- Ongoing virus activity associated with an intra-host viral reservoir
- Autoimmunity
- Inadequate antibody response
Ocular implications of long COVID
While diagnostic and therapeutic efforts have mainly focused on the respiratory and hematological complications of the disease, several ocular implications of LC have also emerged.9 Some cases of COVID-19 showed ocular surface alterations with possible viral detection in tear fluid.10
The most common ocular surface findings are:11
- Bilateral conjunctival hyperemia
- Epiphora
- Foreign body sensation
- Itching
- Eyelid swelling
- Mucopurulent discharge
Figure 1: Patient with aqueous deficiency dry eye disease (DED). Note the moderate-to-severe staining.
Figure 1: Courtesy of Karl Stonecipher, MD.
Small nerve fiber loss and increased dendritic cell density have been found in corneas of LC patients, as well as significantly altered pupillary light responses and impaired retinal microcirculation.12
SARS-CoV-2 can infect and replicate in retinal and brain organoids.12 Organoids are small, lab-grown tissue models that replicate the structure and function of human organs, offering alternatives to animal models.
Other ocular manifestations of LC include retinal hemorrhages, cotton wool spots, and retinal vein occlusion (RVO).12 Scleritis, uveitis, endogenous endophthalmitis, corneal graft rejection, retinal arterial occlusion (RAO), non-arteritic anterior ischemic optic neuropathy (NAION), glaucoma, and neurological and orbital sequelae have all been reported.13
Figure 2: At left, a perfused CRVO. At right, a nonperfused CRVO.
Figure 2: Courtesy of Joseph Pizzimenti, OD and Carlo Pelino, OD.
Figure 3: CRAO with standard photo and red-free.
Figure 3: Courtesy of Joseph Pizzimenti, OD and Carlo Pelino, OD.
Figure 4: Optic disc edema in AION.
Figure 4: Courtesy of Joseph Pizzimenti, OD and Carlo Pelino, OD.
Commonly reported ocular symptoms and signs of long COVID include:9,10,11,13
- Dry eye disease
- Conjunctivitis
- Blurred vision
- Eye pain
- Photophobia
- Floaters
- Neuro-ophthalmic effects, including optic neuritis
- Retinal changes
- Microvascular abnormalities
- Cotton wool spots
- RVO
- Retinal hemorrhage
Diagnostic challenges in clinical practice
As previously mentioned, there is no clear-cut diagnostic biomarker or other definitive diagnostic criterion for LC. Therefore, clinicians must remember to include LC in differential diagnoses for symptoms or conditions with no apparent cause.
Currently, no laboratory test can be used to definitively diagnose LC or to distinguish it from conditions with different etiologies. A positive SARS-CoV-2 viral test or serologic (antibody) test is not required to establish a diagnosis of LC, but can help assess for current or previous infection.
Guidance on evaluating patients for ocular sequelae of long COVID:
- Include questions about COVID prior infection and LC in the case history.
- Complete a full clinical evaluation based on signs and symptoms reported by the patient.
- Diagnostic examination should include tear film assessment, conjunctival examination, pupil and extraocular muscle (EOM) testing, biomicroscopy, and a dilated fundus examination.
- Consider macular OCT, ganglion cell analysis, optic nerve/RNFL OCT, and visual field testing.
Management strategies for systemic and ocular manifestations of LC
While there is currently no specific pharmacotherapy for LC, several symptomatic treatments have been shown to alleviate disease burden. Additionally, emerging evidence highlights the potential role of dietary interventions (e.g., anti-inflammatory diets and micronutrient supplementation) and probiotics in modulating gut–lung axis dysfunction and systemic inflammation.14,15
Pulmonary rehabilitation, encompassing aerobic and resistance training, breathing exercises, and education, has been demonstrated to improve exercise capacity, dyspnea, and quality of life in LC patients.16
For patients who present with ocular complications associated with LC, optometrists should treat, manage, and co-manage these individuals just as they would in non-LC patients, with a few caveats:
- While not fully immunocompromised in the classical sense, many patients with LC experience significant immune system dysregulation that can make them vulnerable to chronic inflammation, autoimmune conditions, and other problems. This should be kept in mind when treating any ocular infection in LC patients.
- Co-manage patients who you suspect of having LC with their infectious disease specialist or primary care physician for confirmation of the diagnosis and systemic management.
- Do not hesitate to co-manage LC patients that develop optic neuritis, ischemic RVO, or RAO with the appropriate ophthalmic subspecialist.
- Connect patients to additional care, services, and supports, as appropriate.
Patient education on long COVID and the eye
Take some time to describe to the patient your examination findings and treatment/management plan, making sure that they understand by having them summarize what you said. Staying informed as a primary healthcare provider should improve early recognition and management of LC. Standardized diagnostic criteria and reliable biomarkers of disease should be developed.
Eyecare providers can help patients with LC by validating their symptoms and connecting them to additional care, services, and supports, as appropriate. Healthcare professionals should adopt integrated, patient-centered care models, including interprofessional collaboration and evidence-supported therapies.
By listening to patients and embracing the complexity of LC, we can provide more effective care and restore quality of life for millions affected worldwide.
Key clinical takeaways
- Long COVID is a serious illness that can result in myriad chronic conditions requiring comprehensive care.
- Long COVID can include a wide range of ongoing symptoms and signs that can last weeks, months, or even years after COVID-19 illness. These include several ophthalmic findings, from the ocular surface to the retina and beyond.
- Optometrists are an integral part of an interprofessional team in the evaluation, diagnosis, treatment, and management of people living with Long COVID.
