The Evaluation of a Painful Eye (part 1)

Overall eye complaints and problems make up around two to three percent of emergency department and primary care office visits.  

Of the 2-3%, half of these cases are conjunctivitis, hordeolum, or corneal abrasion cases. 

Since the overwhelming majority of cases, where a patient has eye pain, have corresponding ocular signs and symptoms, it is helpful to be familiar with possible diagnoses that the patient may have.

This will help direct our questioning during the history portion of our encounter.

The initial evaluation of a painful eye should assess for vision loss or changes in vision.  If there is vision loss associated with eye pain an emergent referral to ophthalmology is indicated.  

painful eye

painful eye

Am Fam Physician. 2016;93(12):991-998. Copyright © 2016 American Academy of Family Physicians.


Evaluating the Patient

The initial evaluation of a painful eye should assess for vision loss or changes in vision.  If there is vision loss associated with eye pain an emergent referral to ophthalmology is indicated. 

If a patient has complaints of something being “stuck in their eye” or a foreign body sensation, this points towards a corneal etiology, such as an abrasion, keratitis, or foreign body.

However, if a patient has complaints of a gritty or sandy sensation in the eye, it is more likely to be related to conjunctivitis. 

When assessing for keratitis, one should ask about contact lens usage as well as their routine with their lenses.  This includes asking about the patient’s wearing schedule, if they wear contacts overnight, lens hygiene, use of tap water to clean contact lenses, and use of hot tub, swimming, or showering with contact lenses in.  If there are any concerns or risk factors, bacterial or Acanthamoeba keratitis should be considered.

Photophobia can be a sign of corneal involvement; however, photophobia with eye pain can be associated with keratitis or anterior uveitis.  Headaches that are associated with eye pain can be found in angle closure glaucoma, cluster headaches, scleritis, and migraine headaches.

Systemic diseases should be considered for patients with suspected scleritis.  One study has shown that around 50 percent of patients with a diagnosis of scleritis has an associated underlying rheumatologic disease.2  Another study found that approximately 40 percent of patients with optic neuritis will develop multiple sclerosis with a 10-year period.2

It is essential in cases of a patient that presents with a painful eye to be well acquainted with the basic anatomy of the eye, primarily so an adequate examination can be completed in your office. 

The below images go over the basic anatomy as well as a stepwise approach to the evaluation of a patient with eye pain.  Some tools that you will need for an appropriate assessment in your primary care clinic may include Snellen eye chart, penlight, fluorescein eye stain, tonometer, and Wood lamp.

anatomy of the eye

diagnosing the painful eye

Am Fam Physician. 2016;93(12):991-998. Copyright © 2016 American Academy of Family Physicians.


Examing the Eye

Next, we will go through the eye examination components and abnormalities that may be seen that can lead you to the appropriate diagnosis.

All patients who have complaints of eye pain should initially have their vision assessed for vision loss by testing with the Snellen eye chart.  Evaluation should be completed with the patient 20 feet away from the chart.  A gross visual assessment for abnormalities should be completed followed by testing visual fields by confrontation.  This can be achieved by taking a red-topped pen and moving it inward from the outer boundaries of each quadrant until the patient can see it.

Diagnoses that can cause decreased visual acuity include:

  • Herpes simplex virus keratitis
  • Acute angle closure glaucoma
  • Orbital cellulitis
  • Optic neuritis

Acute angle closure glaucoma can cause severe central field defects, but this can also occur in cases of optic neuritis as well.  Significant visual field deficit can be seen in HSV keratitis, wherein ten percent of cases patients’ visual defect in the affected eye is tested at 20/100. 

Overall, most painful eye conditions causing decreased visual acuity will need ophthalmology referral.

Extraocular movement should be tested during the ocular examination.  The patient should focus on a target with both eyes and follow it with their eyes only in four directions. 

If a patient’s intraocular pressure is increased, such as in acute angle closure glaucoma, it may cause problems with eye movement or pain with eye movement.  If a patient has pain with ocular movement some diagnoses may include but is not limited to, optic neuritis, orbital cellulitis, or scleritis.

Next is assessing the anatomic structures in more detail of the eye.  Providers should look for inflammation and erythema of the eyelids.  A hordeolum is an inflamed and tender nodule that can be seen on the external or internal eyelid.

The upper eyelid should be everted to assess for any hidden foreign body, especially if a corneal abrasion is suspected.  If there is unilateral erythema affecting the surrounding ocular tissue, swelling, ptosis of the affected eye, decreased visual acuity, and pain with movement of the eye, orbital cellulitis should be in question.

The eyelid and surrounding tissue should also be assessed for any vesicles or rashes.  If vesicles are present on the eyelid or conjunctiva, this can be consistent with HSV keratitis, whereas vesicles in a larger dermatomal patter surrounding the eye on the forehead, nose, and upper eyelid (in the distribution of the V1 trigeminal nerve) can be consistent with herpes zoster ophthalmicus.

herpes zoster ophthalmicus
Am Fam Physician. 2016;93(12):991-998. Copyright © 2016 American Academy of Family Physicians.


herpes zoster ophthalmicus slit lamp
Am Fam Physician. 2016;93(12):991-998. Copyright © 2016 American Academy of Family Physicians.


The conjunctiva is a thin mucous membrane that covers the posterior eyelids and the anterior sclera.  Erythema of the conjunctiva is a resultant factor of infection or inflammation.  If erythema and injection of the conjunctiva is diffuse, it is more commonly caused by a disease or pathology within the conjunctiva, whereas if there is injection radiating out from the limbus, this is more widely seen with pathology within the uvea or anterior chamber.  This may be due to anterior uveitis or acute angle closure glaucoma.

The sclera is a protective coating of the eye.  The sclera has a bluish coloration which helps differentiate it from the episclera for the diagnosis of scleritis versus episcleritis.  Inflammation of the sclera is typically painful, whereas inflammation of the episclera is not painful.  Scleritis will additionally affect the vision, and episcleritis often does not.  Lastly, episcleritis leads to filling of the most superficial blood vessels, and are blanchable with use of topical phenylephrine on examination.

The cornea is a transparent covering of the anterior portion of the eye.  Assessment of the cornea should take place with fluorescein staining with Wood lamp evaluation.  A corneal abrasion under fluorescein staining will show a fluoresce green lesion that is often linear, or several punctate lesions that form a round central defect in those who wear contacts.  Herpetic keratitis has a branching, dendritic appearance under fluorescein staining.

corneal abrasion
Am Fam Physician. 2016;93(12):991-998. Copyright © 2016 American Academy of Family Physicians.

Normal pupillary size is 2 to 4 mm in size, and each pupil should constrict with direct and consensual light exposure.  Anisocoria, an unequal pupil size, (like our patient with Horner syndrome in our past article; link) that occurs with eye pain can be a sign of anterior uveitis.  If the pupil is fixed at 4 to 6 mm in size even with light exposure, this can be indicative of acute angle closure glaucoma.

The swinging flashlight test is used to diagnose if an afferent pupillary defect (Marcus Gunn pupil) is present.  The defect is present in a pupil that dilates when the light is swung to it from the opposite pupil (affected eye constricts more with consensual light than direct light exposure).  This can be indicative of potential optic neuritis, however, if this finding is not present it does not rule out optic neuritis.

The anterior chamber of the eye is between the cornea and iris and is filled with aqueous humor.  This fluid is absorbed where the cornea and iris meet at the Schlemm canal.  The oblique flashlight test can be used to assess the depth of the anterior chamber.  The provider will shine a light tangentially across the cornea from the temporal side.  If illumination of the entire cornea is present, this tells us that there is a wide anterior chamber angle, and a shadow over the nasal portion of the cornea tells us that there is a narrow-angle.  Acute angle-closure glaucoma will be more likely in those with a narrow angle.


Is Imaging Required?

There are a few etiologies and indications where imaging is necessary for the evaluation of eye pain.  If a patient is suspected to have optic neuritis, then MRI of the brain and orbits with contrast is indicated.  If orbital cellulitis is suspected, then a CT scan of the orbits and sinuses are indicated to confirm the potential diagnosis and rule out any abscess formation.

Specific diagnoses should warrant immediate referral and evaluation by an ophthalmologist or hospital admission.  If there is a history of eye trauma with the presence of a hyphema, acute angle closure glaucoma, scleritis, anterior uveitis, optic neuritis, and infectious keratitis (HSV, bacterial Acanthamoeba, and herpes zoster ophthalmicus) all require urgent referral and evaluation by ophthalmology.  Orbital cellulitis requires hospital admission with broad-spectrum antibiotics and ophthalmology consultation.

Keep an eye open for our next article which applies some of the skills from the evaluation of a painful eye in an exciting and rare patient case!


  1. UpToDate. Clinical Manifestations and Diagnosis of Scleritis. Accessed: September 10, 2018.
  2. Am Fam Physician. Evaluation of the Painful Eye. 2016;93(12):991-998. Copyright © 2016 American Academy of Family Physicians.
  3. The Red Eye and PANCE Review by Laurie Ryznyk, MPAS, PA-C, DFAAPA. Southern Illinois University School of Medicine Physician Assistant Program. May 2016.