Cause: Genetic predisposition, hyperopia (farsightedness); after LASIK procedure (J Cataract Refract Surg 2000;26:620); intranasal cocaine (J Laryngol Otol 1999;113:250).

Epidem: Approximately 0.2% of population; especially in middle-aged and elderly (> 50 yr of age).

Pathophys: Smaller eye with shallow anterior chamber that impedes the normal aqueous humor flow, trapping the fluid posteriorly. Pressure then builds, compressing the optic nerve.

Sx: Rainbow halos; eye pain that is sudden and bilateral; headache; nausea and vomiting; scotomas in nasal fields; precipitated by mydriatics, antacids, anesthesia, and darkness.

Si: Red eye, especially circumcorneal; partially dilated fixed pupil; corneal edema with blistering and haziness; visual field defects (Graefes Arch Clin Exp Ophthalm 1999;237:908); corneal pressure > 30 mm Hg—pressures > 18 mm Hg have a 65% sensitivity and specificity.

Crs: 3½ % of all patients with tonometry reading of 20-30 mm Hg will go on to glaucoma in 5 yr.

Cmplc: Blindness; other eye affected within 5-10 yr in 40-80%, and use of pilocarpine does not confer protection.

Lab: Tonometry.

N.B. Anesthetic drops used to facilitate tonometry will not take the discomfort away.

Cause: Bacterial 50-80% of the time, mostly pneumococcus in colder climates, consider Staphylococcus, Corynebacteria, Haemophilus (including Koch-Weeks bacillus), chlamydia in warmer climates (Arch Ophthalm 1966;75:639); viral 20% of the time—especially adenovirus; allergic, such as giant papillary conjunctivitis, which is associated with soft contact lens use, trauma, and foreign body, but is truly allergic (Acta Ophthalm Scand suppl 1999;228:17).

Epidem: Second most common reason for red eye; if exclude foreign body, is 95% of the reason for a red eye.

Pathophys: Obvious—inflammation of conjunctiva.

Sx: Sand feeling in eye; discharge from eye(s).

Si: Conjunctival injection; PERRLA and with normal vision; allergic types with preponderance of itching.

Crs: Usually clears in 3-4 d, rarely protracted unless secondary problem (foreign body) or if allergic but treating for infectious.

Cmplc: Protracted course.

Diff Dx: Conjunctivitis associated with paraneoplastic syndrome or inflammatory skin disease—Cicatrizing conjunctivitis (Am J Ophthalm 2000;129:98);
hemorrhagic conjunctivitis with enterovirus 70 (Am J Epidem 1975;102:533).

Lab: None, although consider viral and bacterial cultures for atypical or severe cases.

Emergency Management: Recommend fluorescein with Woods lamp exam for all red eyes with pain looking for corneal abrasion; also consider iritis.

Infectious conjunctivitis: With topical treatment qid: sulfacetamide 10% solution or ointment; TMP/SMX (polytrim) drops are bacteriocidal rather than bacteriostatic and sting less than sulfa; bacitracin/polymyxin ointment; bacitracin/neomycin/polymyxin ointment; gramicidin/neomycin/polymyxin solution; erythromycin 0.5% ointment; gentamicin 0.3% ointment or solution; tobramycin 0.3% solution or ointment; not chloramphenicol 0.02% solution or 1% ointment, which can lead to aplastic anemia, although just as efficacious (J Antimicrob Chemother 1989;23:261); or may try the fluoroquinolones (which are more expensive) which include ciprofloxacin 0.3% solution or ointment, gatifloxacin 0.3% solution, levofloxacin 0.5% solution, moxifloxacin 0.5% solution, or ofloxacin 0.3% solution (Med Lett Drugs Ther 2004;46:25).

Allergic conjunctivitis: (Drugs 1992;43:154; Med Lett Drugs Ther 2004;46:35): Consider the following topical options to both eyes: NSAID ketorolac (Acular) 0.5% 1 drop qid; or antihistamine levocabastine (Livostin) 0.05% 1 drop qid or emedastine (Emadine) 0.05% 1 drop qid; or mast cell stabilizers, such as cromolyn (Crolom) 4% 1-2 drops OU qid or lodoxamide (Alomide) 0.1% 1-2 drops qid; or nedocromil (Alocril) 2% 1-2 drops bid; or pemirolast (Alamast) 0.1% 1-2 drops qid; or mast cell stabilizer/H₁ antihistamine olopatadine (Patanol) 0.1% 1-2 drops bid; or azelastine (Optivar) 0.05% 1 drop bid; or epinastine (Elestat) 0.05% 1 drop bid; or ketotifen (Zaditor) 0.1% 1 drop q 6-12 hr.

Optom Clin 1991;1:119; Am Fam Phys 2004;70:123

Cause: Trauma; extended wear contact lens (Optom Clin 1991;1:123).

Epidem: Most common reason for red eye.

Pathophys: Direct trauma or rubbing causing trauma to cornea for abrasion.

Sx: Teary, red eye.

Si: Usually unilateral conjunctival injection, check under upper and lower eye lids for foreign body. Metallic foreign bodies with more injection.

Crs: Unremarkable if foreign body removed and timely intervention.