Red Eye -2 (Non-Painful)

Last posting we discussed the Painful Red Eye.  Today, we address the much more common complaint of Red Eyes which are non-painful.  When discomfort exists, it’s described as scratchy, gritty, itchy, “something in my eye” and the like.  But NOT frank PAIN.  Conjunctiva don’t hurt like the cornea, iris, uveal tract, and sclera do.

For all the diagnoses today, except the extremely rare Gonorrheal Conjunctivitis, visual acuity will be normal.  If not, and the abnormality persists despite pinholing [see prior post], and you don’t find anything like a chronic cataract to explain it, they should have a full exam by Ophthalmology.

Repeating our Differential:


No Eye PainCommon

Less Common


Painful  !!!

[NOTE AGAIN:  In all pictures below, the bright pure-white spots in pupils are reflections from flash cameras, not eye lesions]

**  VIRAL CONJUNCTIVITIS  —  Far and away the most common cause of conjunctivitis.  I diagnose it primarily by ruling out other possibilities, considering it a diagnosis of exclusion.  We’ll get to those others.  Still, basic parameters include:

  • Symptoms ❤ wks
  • Bilateral, but often begins unilaterally
  • Clear discharge  (yellow crusts in the morning don’t count as “purulent”; commensual bacteria can overgrow any discharge with time)
  • Occasionally a palpable preauricular node (feels like a rice kernel just anterior to the tragus)

**  BACTERIAL CONJUNCTIVITIS  —  Quite uncommon.  I only diagnose it if they patient describes constant, unremitting, non-clear discharge.  I need to see it myself right then and there, in the office.  It can be green, yellow, or milky white — wipe it away, & more appears within minutes.  This is not simply yellow crusts on the lids when they wake up in the morning.

Bacterial conjunctivitis is usually unilateral, but may occasionally be bilateral.

**  GONORRHEAL CONJUNCTIVITIS  —  Rare, but dramatic:  an enormous amount of rapidly progressive purulent discharge, with chemosis (grossly edematous conjunctiva).  Suspect if the patient has genital symptoms too (autoinoculation), though it could also occur from ejaculation in the face.  Painful if involves the cornea; can destroy the entire globe.  Send stat to an ER for admission (needs IV Tx).

**  CHLAMYDIAL CONJUNCTIVITIS  —  Like gonorrhea, in that it’s rare, usually due to auto-inoculation of genital disease, but can also occur from direct contact with semen.  Unlike it, in that it’s much more indolent and not destructive.  Suspect it by sexual history; diagnose it clinically if you see conjunctival follicles on the inner lower lid.


Immigrants from poor areas of the Third World may have trachoma, a different chlamydial serotype from the STD.  Suspect if you elicit a history compatible with chronic or frequently recurrent conjunctivitis that doesn’t seem allergic.  Send to ophthalmology for definitive diagnosis and treatment before permanent scarring [and eventual blindness] ensues.

**  ALLERGIC CONJUNCTIVITIS  —  Caused by seasonal respiratory allergies, i.e. Hay Fever.  Very common.  How to distinguish this from Viral Conjunctivitis:

  • Nasal symptoms, if present, include lots of sneezing
  • If duration is >3 weeks, it’s not viral
  • If there’s a history of recurrences, and especially if a past episode lasted >3 weeks, or was accompanied by lots of sneezing

First episode, at its onset, is impossible to distinguish.  But treatment is almost the same: a) Time; b) Cool compresses; c) Maybe topical antihistamines; d) No topical antibiotics.  Only difference is that if you suspect allergic conjunctivitis, oral antihistamines are drug-of-choice.  If the eyes feel real itchy with viral conjunctivitis, you can recommend one as well.

**  CONTACT ALLERGY  —  May be due to facial cosmetics, but most commonly to eye drops the patient has used (or has been given).  Especially antibiotic drops, like sulfonamides, neomycin, etc.  History provides a clue.

**  CONJUNCTIVAL FOREIGN BODY  —  Causes a foreign-body sensation [duh].  Usually presents acutely; within a day or two, the culprit will have been washed out by tears.  But you have to invert the upper lid to make sure nothing’s stuck there.  If it makes it to the cornea, frank eye pain ensues.

**  EPISCLERITIS  —  As opposed to Scleritis, which is rare and painful, Episcleritis is uncommon & annoying.  It’s usually idiopathic, but may be due to a collagen-vascular disease.  Treatment is time (self-limiting), or maybe NSAIDs (systemic or topical).

Unless you think of it, the condition can easily mimic conjunctivitis, which is much more common.  Some key findings with Episcleritis:

  • The palpebral conjunctiva (linings of upper & lower lids) are spared.  With conjunctivitis, they’re as injected as the bulbar conjunctiva (which covers the sclera)
  • Ocular injection is focal, not completely diffuse.
  • No frank watery discharge with morning crusting (maybe increased tears from rubbing)

When located medially, distinguish it from a pterygium [see below] by:

  • Transient & self-limiting (pterygia are permanent unless removed)
  • Tufts of vessels noted
  • Vessels in a pterygium run neatly longitudinally toward the cornea

Some examples of Episcleritis:


**  INFLAMED PTERYGIUM  —  Easily diagnosed by its location, extending from the medial canthus toward the cornea.  Distinguish it from episcleritis [see above] by:

  • Pterygia are much more common
  • Vessels run longitudinally down the long axis of a pterygium; distribution is more amorphous and tuft-like with episcleritis

** SUB-CONJUNCTIVAL HEMORRHAGE  —  Here the redness is socked-in, & not “injected” (consisting of dilated vessels).  And there’s no other symptom like itchiness or foreign-body sensation, certainly no pain.  No tenderness on exam (gently wiggle the globe through closed eyelids).

Maybe you can elicit a history of recent valsalvas, like coughing, pushing in labor, lifting a piano, etc.  Just beware if the sub-conjunctival hemorrhage occurred from blunt trauma (will discuss next posting).

Summarizing Findings & Diagnoses for NON-PAINFUL RED EYES:

Thin, Watery Discharge (Most likely Viral or Allergic Conjunctivitis)

Sx present ❤ wks, No other Dx below likely
  • Viral Conjunctivitis
Concurrent Sx of Allergic Rhinitis; OR
Sx present >3 wks; OR
History of frequent recurrences
  • Allergic Conjunctivitis
History of recent eye-drop use; OR
Eye cosmetics galore
  • Contact allergy
Follicles on lower palpebral conjunctiva (lining eyelid)
Sx present several wks (esp. if Hx ? recent genital STD)
  • Chlamydia conjunctivitis
 Unilateral, and Foreign Body noted stuck under upper lid
  • Foreign Body
Focal Injection of only the bulbar conjunctiva (over the sclera), NOT the palpebral conjunctiva (lining the eyelids)
  • Episcleritis

Thick Discharge

Profuse discharge, wipe it away & more recurs within minutes (white / yellow / green):
  • Bacterial conjunctivitis
Discharge as horrible as imaginable, covers the entire eye
(esp. if genital STD Sx present)
Conjunctival chemosis (edema)
  • ? Gonorrhea.  Send to ER.

No Discharge

Focal bulbar conjunctival injection, with NO injection of palpebral conjunctiva
  • Episcleritis (tufts of vessels noted, FB sensation felt)
  • Subconjunctival Hemorrhage (no FB sensation; just blood on exam, no vessels; no tenderness wiggling the globe through closed eyelids; maybe Hx recent valsalvas)
  • Inflamed Pterygium (typical medial location of pterygium)
Injected conjunctiva — both bulbar (over sclera) & palpebral (lining the eyelids)
 Sx ❤ wks, and no other Dx above likely
  • Viral Conjunctivitis

That’s it for Red Eyes [not the airplane flights].  Next posting, Black Eyes (how to systematically address Blunt Eye Trauma).

2 responses to “Red Eye -2 (Non-Painful)

  1. Thank you! I love how you explain everything so clearly and concisely.

  2. Everything is very open with a precise clarification of the
    issues. It was definitely informative.Your site is useful.
    Thank you for sharing!

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s