It’s Friday night, and the clinic is closing in less than an hour when you receive an emergency call. The patient complains of a red eye. How many optometrists can relate to this scenario?
Red eye is one of the most common ocular concerns that arise on a weekly basis in the offices of optometrists and physicians. Most patients continue to visit their physicians for these concerns. An Australian study found that 64% of treated cases by primary care physicians were misdiagnosed and 10% led to serious complications.6 Misdiagnosis and not knowing when to refer the patients can result in devastating consequences. Before going over a few common conditions, let’s go back to the basics.
Back to the basics
One of the basic aspects as physicians is communication. Taking an in-depth case history and determining the patient’s chief complaint is beneficial to streamline the eye examination. The chief complaint of red eyes may yield an extensive list of differentials and a detailed case history can formulate differential diagnoses. Listed below are a few important questions.
Case history for red eye
Frequency | Previous episode or history? |
---|---|
Onset | Acute vs Chronic? |
Location | Unilateral or Bilateral? Diffuse or Localized? |
Duration | How long have symptoms been present? |
Alleviating factors | Use of artificial tears or other eye drops? Cold compresses? |
Related symptoms | Discharge? Burning? Tearing? Itching? Pain? Photophobia? Foreign body sensation? Blurry vision? |
Quality | Pain threshold? (on scale of 1 to 10) |
Ocular history | |
Medical/Social history |
Communication, observations and listening to key phrases can narrow down a list of differential diagnoses. For example: a patient says ‘My eyes are always itchy’ which may indicate allergies or if your patient walks into the exam room wearing sunglasses, the patient may be photophobic. Good communication skills and bedside manner are critical skills for all physicians and can help lead to a more accurate diagnosis for the patient.
This article is a review of a few conditions commonly associated with red eyes, listed in order of urgency of the conditions (least to most urgent).
- Subconjunctival hemorrhage
- Dry eye syndrome
- Conjunctivitis
- Contact lens related problems
- Episcleritis/Scleritis
- Iritis
- Foreign body & Corneal abrasion
Subconjunctival hemorrhage
Subconjunctival hemorrhage is defined as diffuse or focal area of blood under the conjunctiva due to ruptured conjunctival blood vessel. Patients are usually asymptomatic.

Figure 1: Subconjunctival hemorrhage2
Key phrase | “I did not notice anything until someone said something.” |
---|---|
Etiology | |
Signs | |
Treatment | |
Follow up |
Dry eye syndrome
Keratoconjunctivitis sicca, also known as dry eye syndrome, is caused by decreased tear production or poor tear quality. It may be associated with increased age, female > male, medications and some medical conditions.
Key phrase | “My eyes are watering and I feel like something is in it.” |
---|---|
Symptoms | |
Signs | |
Treatment | |
Follow up | Depends on severity |
Conjunctivitis
Conjunctivitis is the most common cause of red eyes, viral being the most prevalent. The term conjunctivitis refers to the inflammation of the conjunctiva. Below are a few clinical pearls for differentiating viral, bacterial and allergic conjunctivitis.
Viral Conjunctivitis

Figure 2: Viral conjunctivitis2
Key phrase | “I think I have pink eye.” |
---|---|
Prevalence | Most prevalent (80%) |
Contagious | Highly for 10-12 days |
Medical history | Recent upper respiratory tract infection(cough/flu) |
Location | Unilateral or bilateral |
Symptoms | |
Discharge | Watery |
Preauricular nodes | Tender nodes |
Other signs | |
Treatment | |
Counseling | |
Follow up | 2 weeks or sooner if condition worsens |
Bacterial Conjunctivitis

Figure 3: Bacterial conjunctivitis3
Key phrase | |
---|---|
Prevalence | |
Contagious | Yes |
Medical history | None |
Location | Unilateral or bilateral |
Symptoms | |
Discharge | White/yellow purulent |
Preauricular nodes | No |
Other signs | |
Treatment | Broad spectrum antibiotic (5-7 day course) |
Counseling | Avoid touching eyes |
Follow up | 2-3 days then every 5-7 days until resolved |
Allergic conjunctivitis

Figure 4: Allergic conjunctivitis2
Key phrase | “My eyes are itchy." |
---|---|
Prevalence | During allergy season |
Contagious | No |
Medical history | |
Location | Usually bilateral |
Symptoms | Itching & burning |
Discharge | Watery |
Preauricular nodes | No |
Other signs | |
Treatment | |
Counseling | |
Follow up | 1-2 weeks |
Contact lens related problems
Contact lenses are used for correcting refractive errors, for cosmetic use and for therapeutic use such as bandage lens. However, contact lens overwear may cause several complications including giant papillary conjunctivitis, superior limbic keratoconjunctivitis & corneal ulcer.
Giant Papillary Conjunctivitis

Figure 5: Giant papillary conjunctivitis3
Key phrase | “My eyelids feel heavy and I need to rub them.” |
---|---|
Etiology | |
Symptoms | |
Signs | |
Treatment |
|
Follow up | 2-4 weeks |
Superior Limbic Keratoconjunctivitis

Figure 6: Superior limbic keratoconjunctivitis2
Key phrase | |
---|---|
Etiology | Hypersensitivity/toxicity reaction to preservatives in contact lens solution |
Symptoms | |
Signs | |
Treatment | |
Follow up | 2-4 weeks |
Corneal Infiltrate & Corneal Ulcer

Figure 7: Corneal ulcer3
Key phrase | "My eyes are red and hurt.” |
---|---|
Etiology | |
Symptoms | |
Signs | |
Treatment |
|
Follow up |
Episcleritis & Scleritis
Episcleritis is a localized area of inflammation of connective tissue between sclera and conjunctiva involving whereas scleritis is defined as an inflammation of the scleral tissue.
Episcleritis

Figure 8: Episcleritis3
Key phrase | “My eye is red in the corner.” |
---|---|
Epidemiology | |
Etiology | |
Symptoms | |
Signs | |
Treatment | |
Follow up | 1 week |
Prognosis |
Scleritis

Figure 9: Scleritis3
Key phrase | “My eye is red and it hurts.” |
---|---|
Epidemiology | 40% diffuse, 44% nodular, 14% necrotizing |
Etiology | |
Symptoms | |
Signs | |
Treatment | |
Follow up | 1 week or sooner if symptoms worsen |
Prognosis |
Iritis
Iritis, also known as anterior uveitis, is an idiopathic inflammation of uvea (iris, choroid and/or ciliary body).

Figure 10: Keratic precipitates3
Key phrase | “I am light sensitive.” |
---|---|
Symptoms | |
Signs | |
Treatment | |
Follow up |
Foreign body & corneal abrasion
Defined as defects to the corneal epithelium, corneal abrasion can cause irritation, pain, tearing and photophobia.

Figure 11: Corneal abrasion3
Key phrase | “Something got into my eye and it hurts.” |
---|---|
Risk factors | |
Symptoms | |
Signs | |
Treatment | |
Follow up |
Conclusion
Red eye is the most common complaint found amongst patients and the concept that every case is a ‘pink eye’ is a huge misunderstanding. The average person will call their family physician if they have an eye problem. There is a misconception that optometrists only provide a spectacle prescription. Upon questioning patients, they are often unaware that optometrists may provide more detailed care including urgent eye problems. Reaching out to family physicians and providing reports for mutual patients can build a foundation for better communication between optometrists and family physicians. Educating patients and the public with regards to our role as primary care optometrists may help to prevent misdiagnosis and further patient consequences. Stay tuned for more details regarding atypical conditions in association with red eyes.
Citations
- Cronau H, Kankanala R, Mauger T. Diagnosis and Management of Red Eye in Primary Care. American Family Physician. 2010;81(2):137-144.
- Ehlers JP, Shah CP, Fenton GL. Wills Eye Manual Office and Emergency Room Diagnosis and Treatment of Eye Disease. Philadelphia, PA: Wolters Kluwer Health; 2012.
- Friedman NJ, Kaiser PK. The Massachusetts Eye and Ear Infirmary: Illustrated Manual of Ophthalmology. Philadelphia, PA: Saunders, Elsevier; 2014.
- Frings A, Geerling G, Schargus M. Red Eye: A Guide for Non-specialists. Deutsches Arzteblatt International. 2017;114:302-312. doi:10.3238
- Gilani C, Yang A, Yonkers M, Boysen-Osborn M. Differentiating Urgent and Emergent Causes of Acute Red Eye for the Emergency Physician. Western Journal of Emergency Medicine. 2017;18(3):509-517. doi:10.5811
- Statham MO, Sharma A, Pane AR. Misdiagnosis of acute eye diseases by primary health care providers: incidence and implications. Med J Aust. 2008;189:402–404
- Vo A, Williamson J. Red Eye Roundup. Review of Optometry. https://www.reviewofoptometry.com/article/red-eye-roundup. Published March 15, 2019. C