Understanding Contact Lens Pathology and Management: A Deep Dive for Optometry Students

Below is a summary of the main learning points from the webinar:

1. Epithelial Microcysts

Epithelial microcysts appear as tiny scattered dots visible under retro illumination, often showing reversed illumination due to their higher refractive index. They consist of non-viable epithelial cells migrating from the basal layer to the surface.

While small numbers are normal and asymptomatic, large numbers can cause reduced visual acuity. These typically arise due to chronic hypoxia from extended wear of hydrogel lenses with low oxygen permeability (low Dk).

Key Points:

• Cause: Prolonged hypoxia → metabolic stress → reduced oxygen uptake → epithelial thinning
• Common in: Hydrogel extended wear lenses
• Resolution: Improves after switching to high Dk materials (e.g. silicone hydrogel)
• Management:
  • Switch from hydrogel to silicone hydrogel or rigid lenses
  • Ensure appropriate lens fit and oxygen permeability
  • Reassess after 3 months — microcysts often reduce significantly

2. Mucin Balls

Mucin balls are small, round, translucent bodies located between the posterior lens surface and the cornea. They often resemble collapsed doughnuts and can be seen using retroillumination techniques.

They are common in silicone hydrogel extended wear, not due to hypoxia but due to the material’s increased modulus and stiffness, which induces shearing forces during blinking.

Key Points:

• Common signs: Small, stationary translucent rings behind the lens
• Symptoms: Usually asymptomatic unless numerous or in the visual axis
• Causes: Lens stiffness, prolonged wear, tear film characteristics
• Management:
  • Switch from extended wear to daily wear
  • Use a lens with lower modulus
  • Prescribe ocular lubricants for a flushing effect

3. Corneal Staining

Corneal staining is one of the most frequently observed signs in contact lens wearers. It presents as punctate, diffuse, or coalescent hyperfluorescent areas, indicating epithelial disruption.

Common Causes:

• Mechanical trauma from lens movement
• Solution toxicity (especially with PHMB-containing solutions)
• Dryness and poor tear distribution
• Ill-fitting lenses
• Management:
  • Adjust lens parameters (edge lift, thickness, diameter)
  • Use more wettable materials or mini-sclerals/hybrids
  • Reduce wearing time
  • Review and change solution or care regime

4. Solution-Induced Corneal Staining (SICS)

SICS is typically seen beyond the limbus and peaks 1–2 hours after lens insertion, resolving after lens removal. It’s most commonly linked to PHMB-based multipurpose solutions.

Key Points:

• Symptoms: Mild burning or discomfort (often asymptomatic)
• Cause: Solution toxicity, not cell death (as fluorescein uptake requires viable cells)
• Management:
  • Change to a different disinfecting solution
  • Consider hydrogen peroxide systems for sensitive patients

5. SEALs — Superior Epithelial Arcuate Lesions

SEALs appear as arcuate staining in the superior cornea, caused by mechanical interaction between the lens and upper lid. They are commonly associated with stiffer, higher-modulus materials like silicone hydrogels.

Management:

• Cease lens wear temporarily
• Refitting with softer or thinner-edge materials
• Increase Dk if metabolic cause suspected
• Treat secondary infection if present

6. Contact Lens-Associated Infiltrative Keratitis (CLAIK)

CLAIK can be non-severe or severe, and though relatively uncommon, should always be taken seriously. It presents with infiltrates, often in extended wear users, but can also occur with daily lenses.

Management:

• Same-day referral for suspected keratitis
• Always treat contact lens peripheral ulcers (CLPU) as microbial keratitis until proven otherwise
• Pseudomonas is the most common pathogen (responsible for >50% of cases)
• Ensure patient brings their lenses for microbial swabbing

7. Giant Papillary Conjunctivitis (GPC)

GPC is an immunological response to lens deposits or mechanical irritation from stiff lens materials. It presents with papillae on the tarsal conjunctiva, often accompanied by itching, mucus discharge, and lens intolerance.

Management:

• Cease lens wear for 2–4 weeks
• Switch to more frequent replacement lenses
• Prescribe mast-cell stabilisers or antihistamines
• Regular follow-ups — papillae may take time to resolve

8. RGP Complications

Although RGP lenses are less common, they come with distinct complications:

Common Issues:

• Corneal abrasions: Due to handling or damaged lenses
• Dimple veiling: Air bubbles trapped under a steep lens, visible with fluorescein
• Three-and-nine o’clock staining: Due to inadequate tear distribution at the periphery
• Management:
  • Adjust lens curvature or diameter
  • Increase edge clearance
  • Use lubricants and reduce wear time
  • If untreated, can lead to peripheral thinning and scarring (Dellen)

Final Thoughts

Contact lens complications range from mild staining to sight-threatening keratitis. As an optometry student, understanding pathophysiology, recognition, and management of these conditions is crucial to ensure safe lens wear and excellent patient outcomes.

Remember: when in doubt, refer. Early recognition and appropriate management protect not only your patient’s vision but also your confidence as a future clinician.