What are the dangers associated with contact lens use?

Dangers of Contact Lenses

The most serious danger of contact lens wear is microbial keratitis, which can cause permanent vision loss even with proper treatment, and overnight wear increases this risk fivefold compared to daily wear. 1

Most Serious Complications

Microbial Keratitis (Vision-Threatening)

• Bacterial keratitis is the most feared complication, with Pseudomonas aeruginosa being the most commonly isolated pathogen in contact lens-associated infections 2
• Annual incidence ranges from 2-20 cases per 10,000 wearers, with overnight wear dramatically increasing risk to 21 per 10,000 versus 4 per 10,000 for daily wear 2, 3
• Can result in permanent vision loss (0.6 cases per 10,000 wearers annually require corneal transplantation or suffer permanent damage) 4
• Acanthamoeba keratitis is particularly difficult to diagnose and treat, strongly associated with water exposure while wearing lenses 1
• Fungal keratitis requires emergency corneal transplantation in 20-30% of severe cases 4

Why Overnight Wear Is So Dangerous

• Overnight wear carries a fivefold relative risk of corneal infections compared to daily wear 1, 5
• Even occasional overnight wear significantly increases risk and should be discouraged 1
• Pseudomonas adheres readily to contact lens deposits that accumulate with prolonged use 1, 2

Common Non-Infectious Complications

Hypersensitivity and Surface Problems

• Giant papillary conjunctivitis is a frequent hypersensitivity reaction in long-term wearers 1, 2
• Superficial keratitis, recurrent corneal erosions, and Salzmann nodules 1
• Subepithelial fibrosis and opacification 1
• Limbal stem cell deficiency from chronic wear 1, 2

Corneal Changes

• Corneal neovascularization from chronic hypoxia 1, 2
• Transient stromal edema and corneal thinning (epithelium and stroma) 1, 2
• Endothelial changes including polymegethism, pleomorphism, and rarely reduced cell density 1
• Corneal warpage requiring monitoring with keratometry or topography 1

Critical Risk Factors and Behaviors

Hygiene Failures (Nearly Universal)

• 99% of contact lens wearers report at least one hygiene risk behavior 1, 2, 6
• Approximately one-third of all wearers have experienced red or painful eye conditions requiring a doctor visit 1, 2
• Only 34% of patients who believe they are compliant actually exhibit good lens care practices 1

Specific High-Risk Behaviors

• Water contact is extremely dangerous: swimming, showering, hot tubs, bathing, or washing hair while wearing lenses 1, 2, 5
• Rinsing lenses or cases with tap water, bottled water, or homemade saline 1, 2, 5
• Failure to replace lens cases every 3 months (cases become contaminated reservoirs) 1, 2, 5
• "Topping off" solution instead of using fresh solution each time 1
• Using lenses beyond recommended replacement schedules 1

Absolute and Relative Contraindications

When Contact Lenses Should Not Be Used

• Keratoconjunctivitis sicca (dry eye) 1, 2
• Blepharoconjunctivitis or acne rosacea 1, 2
• Active inflammation of the anterior segment 1
• Use of topical corticosteroids 1
• Presence of a filtering bleb 1
• Poor personal hygiene (dirty hands and fingernails) 1
• Dusty environments or exposure to volatile chemicals 1
• History of previous corneal complications from contact lenses 1
• Limited dexterity or inability to understand risks 1

Special Consideration for Monocular Patients

• The risks of contact lens complications must be weighed against the protective benefit of eyeglasses for patients with good vision in only one eye 1

Warning Signs Requiring Immediate Lens Removal

Red Flags for Serious Infection

• Moderate to severe pain (may indicate corneal abrasion, infection, or Acanthamoeba keratitis) 2, 7
• Decreased vision or photophobia 2
• Purulent discharge 2, 7
• Persistent symptoms beyond expected timeline 7

Common Pitfalls to Avoid

Patient Education Failures

• Patients often believe they are compliant when they are not—direct questioning about specific behaviors is essential 1
• Decorative and costume contact lenses are medical devices requiring prescriptions, but are often sold without proper oversight 1
• Hydrogen peroxide systems may be superior for disinfection but require more complex care regimens that patients may not follow correctly 1, 5

Clinical Management Errors

• Failing to reinforce that even FDA-approved extended-wear lenses carry significant overnight risk 1
• Not scheduling regular examinations (every 1-2 years) to monitor lens fit, ocular health, and reinforce hygiene 1
• Underestimating the severity of contact lens-related infections, which can progress rapidly 8, 4