The Optometrist's Guide to Red Eye

Jun 5, 2020
11 min read

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
  • History of trauma or chemical injury?
  • Exposure to an infected person?
  • Contact lens wearer?
  • Use of topical or over the counter drops?
  • Medical/Social history
  • Recent illness or infections?
  • Computer use?
  • Occupation?
  • Smoking 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).

    1. Subconjunctival hemorrhage
    2. Dry eye syndrome
    3. Conjunctivitis
    4. Contact lens related problems
    5. Episcleritis/Scleritis
    6. Iritis
    7. 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.”
  • Idiopathic
  • Valsalva (coughing, sneezing, constipation)
  • Trauma (isolated or associated with retrobulbar hemorrhage or ruptured globe)
  • Systemic conditions (hypertension, diabetes)
  • Bleeding disorders
  • Use of antiplatelet or anticoagulant medications (aspirin, clopidogrel, warfarin)
  • Signs
  • Focal or diffused hemorrhage
  • Rule out conjunctival lesions and ruptured globe (check extraocular motility, intraocular pressure)
  • If recurrent or suspect bleeding disorder, refer for blood work (bleeding time, prothrombin time, partial thromboplastin time, complete blood count, liver function test, protein C and protein S)
  • Treatment
  • Condition is self-limiting with spontaneous resolution within 2-3 weeks
  • Artificial tears may be given if ocular irritation is present
  • Follow up
  • No follow up necessary unless condition reoccurs
  • Refer to family doctor for high blood pressure and bleeding disorder if recurrent
  • 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.”
  • Burning/Dryness
  • Foreign body sensation
  • Excessive tearing
  • Signs
  • Scant, irregular tear prism at inferior eyelid margin
  • Decreased tear break-up time
  • Punctate corneal or conjunctival staining
  • Excess mucus or debris in tear film
  • Meibomian gland dysfunction
  • Treatment
  • Artificial tears
  • Lubricating ointment QHS or lubricating gel QHS
  • Lifestyle modifications (use of humidifiers, smoking cessation)
  • Cyclosporine 0.05% BID for chronic dry eye
  • Follow up Depends on severity


    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
  • Itching/Burning
  • Foreign body sensation
  • Tearing
  • Discharge Watery
    Preauricular nodes Tender nodes
    Other signs
  • Follicles inferiorly
  • Edematous eyelids
  • Intraepithelial microcyst
  • Subepithelial infiltrates
  • Treatment
  • Self-limiting; however, palliative therapies include:
  • Artificial tears
  • Mild steroid (if necessary)
  • Counseling
  • Copious handwashing
  • Avoid touching eyes
  • Follow up 2 weeks or sooner if condition worsens

    Bacterial Conjunctivitis


    Figure 3: Bacterial conjunctivitis3

    Key phrase
  • “My lids are shut closed when I wake up.”
  • “My eyes are goopy.”
  • Prevalence
  • Second most prevalent
  • Children > Adults
  • Contagious Yes
    Medical history None
    Location Unilateral or bilateral
  • Foreign body sensation
  • Matted eyelashes
  • Discharge White/yellow purulent
    Preauricular nodes No
    Other signs
  • Conjunctival papillae
  • Moderate hyperemia
  • Conjunctival chemosis
  • 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
  • Seasonal allergies
  • Airborne allergens
  • Location Usually bilateral
    Symptoms Itching & burning
    Discharge Watery
    Preauricular nodes No
    Other signs
  • Conjunctival papillae
  • Mild hyperemia
  • Conjunctival chemosis
  • Red edematous eyelids
  • Treatment
  • Cold compresses
  • Artificial tears
  • Anti-histamine or Mast cell inhibitors
  • Mild steroid (if necessary)
  • Oral anti-histamine (if necessary)
  • Counseling
  • Eliminate allergen
  • Avoid rubbing eyes
  • 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.”
  • Contact lens overwear
  • Loose fit (excessive lens movement)
  • Symptoms
  • Itching & burning
  • Foreign body sensation
  • Signs
  • Upper tarsal micropapillae
  • Superior limbal injection
  • Ropy mucous discharge
  • Treatment
  • Educate patient on proper contact lens care
  • For mild GPC:
    • Decrease wear time of contact lenses
    • Topical mast cell inhibitor or antihistamine
  • For severe GPC:
    • Suspend use of contact lenses
    • Topical steroid
    Follow up 2-4 weeks

    Superior Limbic Keratoconjunctivitis


    Figure 6: Superior limbic keratoconjunctivitis2

    Key phrase
  • “I cannot wear my contacts for long anymore.”
  • “I have to take out my contact lenses more often.”
  • Etiology Hypersensitivity/toxicity reaction to preservatives in contact lens solution
  • Itching & burning
  • Foreign body sensation
  • Contact lens intolerance
  • Signs
  • Upper tarsal micropapillae
  • Superior limbal injection
  • Pannus at 12 o’clock
  • Treatment
  • Suspend use of contact lenses
  • Switch to preservative free contact lens solution
  • Use preservative free artificial tears
  • Topical steroid (if necessary)
  • Follow up 2-4 weeks

    Corneal Infiltrate & Corneal Ulcer


    Figure 7: Corneal ulcer3

    Key phrase "My eyes are red and hurt.”
  • Bacterial
  • Fungal
  • Acanthamoeba
  • Symptoms
  • Pain
  • Photophobia
  • Contact lens intolerance
  • Signs
  • White stromal opacity
  • Corneal thinning/ulcer
  • Anterior chamber reaction
  • Treatment
  • Cycloplegic drops for comfort
  • For mild condition:
    • Fluoroquinolone q1-2 hrs
  • For severe condition:
    • Fluoroquinolone q1-2 hrs
    Follow up
  • 1 day
  • Maintain treatment until condition resolves
  • 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.



    Figure 8: Episcleritis3

    Key phrase “My eye is red in the corner.”
  • 80% simple, 20% nodular
  • Bilateral in 33% of cases
  • Etiology
  • Idiopathic
  • Infectious (herpes zoster)
  • Other (rosacea, atopy, collagen vascular disease, gout, thyroid disease)
  • Symptoms
  • Mild pain
  • Hyperemia
  • Signs
  • Sectoral injection
  • Chemosis
  • Episcleral nodules
  • Cells and flare
  • Treatment
  • Artificial tears
  • Topical steroid (Fluorometholone QID)
  • Oral NSAID for severe cases
  • Follow up 1 week
  • Self-limiting condition & good prognosis
  • Recurrent in 67% of cases
  • Scleritis


    Figure 9: Scleritis3

    Key phrase “My eye is red and it hurts.”
    Epidemiology 40% diffuse, 44% nodular, 14% necrotizing
  • Idiopathic
  • Connective tissue disease
  • Herpes zoster ophthalmicus
  • Syphilis
  • Symptoms
  • Severe pain
  • Hyperemia & chemosis
  • Signs
  • Decreased vision
  • Diffused injection
  • Chemosis
  • Scleral nodules
  • Globe tenderness
  • Cells and flare
  • Treatment
  • Oral steroid (Prednisone 60-100 mg po QD)
  • Systemic NSAID
  • Follow up 1 week or sooner if symptoms worsen
  • Depends on etiology (poor for necrotizing)
  • Recurrence is common
  • 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.”
  • Pain
  • Redness
  • Photophobia
  • Decreased vision
  • Signs
  • Anterior chamber reaction (cells and flare)
  • Ciliary flush
  • Keratic precipitates
  • Hypopyon
  • Iris synechiae
  • Treatment
  • Cycloplegic bid
  • Topical steroid (Prednisolone acetate 1% q4-6 hrs depending on severity)
  • May consider steroid ointment overnight
  • Follow up
  • Every 1-7 days depending on severity, assess patient’s IOP at each visit
  • Taper steroid once anterior chamber reaction has resolved
  • 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
  • Foreign body
  • Trauma
  • Contact lens use
  • Symptoms
  • Sharp pain
  • Photophobia
  • Foreign body sensation
  • Tearing
  • Signs
  • Epithelial defect (stains with fluorescein)
  • Conjunctival injection
  • Mild anterior chamber reaction
  • Protective ptosis
  • Treatment
  • For non-contact lens wearer: antibiotic ointment q2-4 hrs or antibiotic drops QID
  • For contact lens wearer: anti-pseudomonas coverage, antibiotic ointment or drop QID
  • For abrasion secondary to fingernail or vegetative matter: Fluoroquinolone QID
  • For large abrasion: place bandage contact lens
  • Follow up
  • For bandage contact lens: follow up within 24 hrs for re-evaluation
  • Central or large abrasion: follow up within 24 hrs for re-evaluation
  • Peripheral or small abrasion: follow up within 2-5 days
  • 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.


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    4. Frings A, Geerling G, Schargus M. Red Eye: A Guide for Non-specialists. Deutsches Arzteblatt International. 2017;114:302-312. doi:10.3238
    5. 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
    6. 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
    7. Vo A, Williamson J. Red Eye Roundup. Review of Optometry. Published March 15, 2019. C
    About Roshni Naik

    Dr. Roshni Naik is a 2016 graduate from New England College of Optometry. She is board certified to practice in Canada and the United States and is qualified to prescribe therapeutic agents for treatment of ocular disease. Dr. Naik is …

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