Unit 4 & 5 - Contact lens ll | 6th Semester Bachelor of Optometry

Complications of Soft Contact Lenses

Introduction

While soft contact lenses (SCLs) offer comfort and convenience, improper usage, poor hygiene, or patient-specific factors can lead to a variety of complications. These complications can range from mild irritation to vision-threatening infections. Early detection and management are crucial to avoid long-term damage and to maintain safe lens wear.

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Classification of Complications

• Mechanical complications – due to lens fit or design
• Hypoxic complications – due to reduced oxygen supply
• Inflammatory complications – due to immune response or microbial colonization
• Infectious complications – due to bacterial, fungal, or protozoal pathogens
• Deposits and toxicity-related – due to solution reactions or tear film interactions

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1. Mechanical Complications

🔹 Contact Lens-Induced Papillary Conjunctivitis (CLPC / GPC)

• Caused by mechanical irritation from lens edge or surface deposits
• Symptoms: Itching, mucous discharge, lens intolerance
• Signs: Giant papillae on upper tarsal conjunctiva
• Management: Discontinue lens temporarily, switch to daily disposables, anti-allergic drops

🔹 Contact Lens-Associated Epithelial Defects

• Mechanical rubbing of tight-fitting or poorly centered lens
• Results in corneal abrasions or epithelial microtrauma
• Fluorescein staining reveals arcuate or linear defects
• Management: Refit lens, reduce wear time, consider lubricants

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2. Hypoxic Complications

🔹 Corneal Neovascularization

• New blood vessels grow into avascular cornea due to chronic oxygen deprivation
• Usually observed in long-term wearers or with low Dk lenses
• Early stages: asymptomatic; advanced: blurred vision, ghosting
• Management: Reduce wear time, switch to silicone hydrogel, monitor every 3–6 months

🔹 Microcysts

• Small epithelial cysts visible with retroillumination
• Indicate chronic hypoxia and epithelial stress
• Often asymptomatic unless large in number
• Management: Improve oxygen availability, refit or discontinue lens temporarily

🔹 Corneal Edema

• Due to fluid accumulation within stroma caused by hypoxia
• Signs: Hazy cornea, striae, folds, halos around lights
• Can progress to bullae and epithelial breakdown
• Management: Reduce wear time, increase oxygen supply

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3. Inflammatory Complications

🔹 Contact Lens Peripheral Ulcer (CLPU)

• Small, round, white corneal infiltrate with overlying epithelial defect
• Cause: Immune response to bacterial toxins (commonly Staph aureus)
• Symptoms: Mild pain, redness, photophobia
• Management: Discontinue lenses, topical antibiotics, monitor healing

🔹 Infiltrative Keratitis

• Presence of white infiltrates without epithelial defect
• Often seen in extended lens wear or solution hypersensitivity
• Management: Cease wear, use topical steroids if needed, switch to preservative-free solutions

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4. Infectious Complications

🔹 Microbial Keratitis (MK)

• Serious, sight-threatening corneal infection
• Pathogens: Pseudomonas, Acanthamoeba, fungi, Gram-positive cocci
• Symptoms: Pain, redness, photophobia, mucopurulent discharge, decreased vision
• Signs: Central corneal ulcer with stromal infiltrate, anterior chamber reaction
• Risk Factors: Overnight wear, poor hygiene, water exposure, smoking
• Management: Emergency referral, culture and sensitivity, intensive topical antibiotics

🔹 Acanthamoeba Keratitis

• Rare but severe infection caused by protozoa found in tap water, pools
• Symptoms: Severe pain disproportionate to signs, ring-shaped stromal infiltrate
• Often misdiagnosed as HSV or bacterial keratitis
• Management: Anti-amoebic drugs (polyhexamethylene biguanide, chlorhexidine), discontinue lens

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5. Deposits and Toxicity

🔹 Protein and Lipid Deposits

• Accumulated tear film proteins denature on lens surface
• Symptoms: Blurred vision, lens intolerance, dryness
• Visible as white/opaque spots under slit lamp
• Management: Use daily disposables or enzymatic cleaners, switch to high water-content lenses

🔹 Solution-Induced Corneal Staining (SICS)

• Diffuse superficial staining due to preservative toxicity (esp. PHMB)
• Usually asymptomatic; found during follow-up
• Management: Switch to preservative-free or hydrogen peroxide-based system

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6. Allergic or Hypersensitivity Reactions

🔹 Solution Allergy

• Redness, itching, burning sensation after lens application
• May involve conjunctival chemosis, papillae
• Management: Use non-preserved solution, cold compress, antihistamines

🔹 Contact Lens-Induced Dry Eye (CLIDE)

• Common in digital users or long wearers
• Symptoms: Foreign body sensation, dryness, irritation
• Management: Rewetting drops, reduce screen time, switch to water-gradient lenses

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7. Preventive Strategies

• Use lenses with high oxygen permeability (Dk/t)
• Strict adherence to lens hygiene and replacement schedule
• Avoid overnight wear unless approved
• Avoid water contact (tap water, pools, lakes)
• Use compatible cleaning and lubricating solutions
• Schedule regular follow-up visits (every 6–12 months)
• Educate patients on early signs of complications

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Conclusion

Complications of soft contact lenses may range from mild irritation to vision-threatening infections. Understanding the pathophysiology, risk factors, clinical signs, and appropriate management allows optometry professionals to ensure safe and effective lens wear. Prevention through proper lens selection, patient education, and regular follow-up remains the best strategy for long-term success.

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References

1. Bennett ES, Henry VA. Clinical Manual of Contact Lenses, 3rd Ed. Lippincott Williams & Wilkins, 2008.
2. Phillips AJ, Speedwell L. Contact Lenses, 5th Ed. Butterworth-Heinemann, 2007.
3. American Optometric Association: Contact Lens Complication Guidelines.
4. British Contact Lens Association (BCLA): Management of Lens-Related Issues, 2022.

Therapeutic Contact Lenses

Indications and Fitting Considerations

Introduction

Therapeutic contact lenses are specially designed medical devices used not for vision correction, but primarily for protecting, healing, or supporting the ocular surface. These lenses play a critical role in managing various corneal diseases, post-surgical care, and ocular trauma. Unlike conventional lenses, their primary purpose is therapeutic — to maintain hydration, act as a physical barrier, deliver medications, or assist epithelial regeneration.

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1. What Are Therapeutic Contact Lenses?

These are typically soft contact lenses (often high water-content hydrogel or silicone hydrogel) prescribed to:

• Promote corneal healing
• Protect the cornea from mechanical trauma (e.g., blinking over a wound)
• Relieve pain by covering exposed nerve endings
• Serve as a drug reservoir

Common Names: Bandage lenses, healing lenses, medicated lenses

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2. Indications for Therapeutic Contact Lens Use

🔹 A. Epithelial Wound Healing

• Corneal abrasions
• Post-epithelial debridement (e.g., in recurrent erosion syndrome)
• Persistent epithelial defects (e.g., neurotrophic keratitis)

🔹 B. Pain Relief

• Bullous keratopathy
• Filamentary keratitis
• Post-PRK or LASIK surface discomfort

🔹 C. Mechanical Protection

• Trichiasis or entropion causing lashes to rub cornea
• Lagophthalmos with exposure keratitis
• Dry eye in patients awaiting tarsorrhaphy or punctal occlusion

🔹 D. Post-Surgical Applications

• After penetrating keratoplasty
• Post pterygium surgery
• Following corneal cross-linking (CXL)

🔹 E. Drug Delivery

• Lenses soaked in antibiotics, anti-inflammatories, or growth factors
• Useful in patients with poor drop compliance

🔹 F. Other Uses

• Post chemical burns
• Thermal or radiation injury
• Corneal degenerations (e.g., Salzmann’s nodular degeneration)

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3. Types of Therapeutic Contact Lenses

🟢 A. Soft Bandage Lenses

• Most commonly used therapeutic lens type
• High water content for maximum hydration
• Available in various base curves and diameters
• Examples: Acuvue Oasys, PureVision, Air Optix Night & Day

🟠 B. Silicone Hydrogel Bandage Lenses

• High oxygen permeability (Dk)
• Suitable for extended wear and post-operative healing
• Examples: Lotrafilcon A, Balafilcon A lenses

🔵 C. Scleral Lenses (Large-Diameter RGP)

• Vault the cornea and rest on sclera
• Used in severe dry eye or exposure keratitis
• Provide fluid reservoir beneath the lens
• Example: BostonSight PROSE

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4. Fitting Considerations

📏 A. Lens Material and Oxygen Transmission

• Use high-Dk materials (preferably silicone hydrogel) to prevent hypoxia
• Especially important in extended wear or post-surgery patients

🔘 B. Base Curve and Diameter

• Choose a base curve that provides adequate centration and minimal movement
• Lens should cover the entire cornea with 1–1.5 mm overlap
• Prefer slightly steeper lenses to reduce movement in healing eyes

🕒 C. Wearing Schedule

• Usually worn for 24–72 hours depending on the condition
• Patients must be reviewed daily or every 2–3 days in severe cases
• Change lens if excessive deposits, drying, or discomfort occur

🧼 D. Hygiene and Handling

• Strict hygiene is essential due to increased infection risk
• Use non-preserved lubricants or prescribed drops over the lens
• Disinfection depends on intended wear — often not removed daily

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5. Precautions and Monitoring

• Daily follow-up required for corneal ulcers, chemical burns, or persistent defects
• Check for:
  • Lens centration and deposits
  • Corneal healing using fluorescein staining
  • Signs of microbial keratitis or infiltrates
• Use prophylactic topical antibiotics if indicated

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6. Contraindications for Bandage Lens Use

• Active microbial keratitis unless under close monitoring
• Severe dry eye with poor tear exchange (unless using scleral lens)
• Poor patient compliance with hygiene or follow-up

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7. Advantages of Therapeutic Lenses

• Faster epithelial healing
• Reduction of ocular pain and photophobia
• Protection of cornea during blinking or eye movement
• Improved patient comfort and functional recovery
• Acts as drug reservoir in specific applications

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Conclusion

Therapeutic contact lenses are an essential tool in ocular surface management. Their ability to promote healing, relieve pain, and support recovery from trauma or surgery makes them invaluable in clinical practice. Proper lens selection, fitting, and vigilant follow-up are crucial to achieving successful outcomes while minimizing complications. As future practitioners, optometry students must be well-versed in their applications and limitations.

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References

1. Bennett ES, Henry VA. Clinical Manual of Contact Lenses, 3rd Ed. Lippincott Williams & Wilkins, 2008.
2. Phillips AJ, Speedwell L. Contact Lenses, 5th Ed. Butterworth-Heinemann, 2007.
3. American Academy of Ophthalmology. Cornea/External Disease Subspecialty Texts, 2022.
4. BCLA. Therapeutic Lens Practice Guidelines, 2023.

Specialty Contact Lens Fitting

Fitting for Aphakia, Pediatric Patients, and Post-Refractive Surgery Eyes

Introduction

Specialty fitting refers to customizing contact lenses for patients with unique ocular conditions or anatomical challenges. Conventional lenses may not provide adequate vision, comfort, or corneal health in such cases. This topic covers three major scenarios requiring specialty contact lens fitting: aphakia, pediatric patients, and post-refractive surgery eyes.

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1. Contact Lens Fitting in Aphakia

🧠 What is Aphakia?

Aphakia refers to the absence of the natural crystalline lens, either due to surgical removal (e.g., cataract surgery), trauma, or congenital causes. It leads to high hyperopia, reduced accommodation, and anisometropia if unilateral.

🔍 Optical Challenges in Aphakia

• High plus power (+10 to +20 D)
• Image magnification (25–30%) with spectacles
• Ring scotoma and prismatic effects with glasses
• Anisometropia in unilateral cases

✅ Advantages of Contact Lenses in Aphakia

• Minimize image magnification (7–10% vs. 25% with spectacles)
• Better binocular vision in unilateral cases
• Improved cosmesis and visual field

👓 Lens Types Used

• Rigid Gas Permeable (RGP): Ideal for high powers and good oxygen permeability
• Silicone Hydrogel Lenses: Higher Dk for extended wear
• Lathe-Cut Lenses: For customized high plus powers

🔧 Fitting Considerations

• Higher lens thickness needed in high plus powers
• Edge lift must be monitored closely for comfort
• Correct over-refraction precisely to avoid ghosting
• Refit regularly as eye heals post-surgery

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2. Contact Lens Fitting in Pediatric Patients

🧒 Indications for Pediatric CL Fitting

• Congenital aphakia
• High ametropia (especially anisometropia)
• Corneal irregularities (e.g., keratoconus)
• Therapeutic use (e.g., exposure keratitis)
• Myopia control in progressing children

📋 Challenges in Pediatric Fitting

• Cooperation from child during fitting and follow-up
• Parental understanding and compliance with hygiene
• Rapid ocular growth requiring frequent refitting
• Difficulty in inserting/removing lenses in infants

👓 Lens Options

• Silicone hydrogel lenses: Preferred for oxygen and comfort
• Custom soft lenses: Made for smaller corneas in infants
• RGP lenses: Used in corneal pathologies or high refractive error
• Daily disposables: Useful for hygiene and myopia control

🔧 Fitting Considerations

• Use steeper base curves for tighter fit in infants
• Ensure proper lens centration and minimal movement
• Schedule frequent follow-up visits (monthly or quarterly)
• Train caregivers on insertion, removal, and hygiene

🎯 Special Role: Myopia Control

Soft multifocal lenses, orthokeratology lenses, or atropine therapy combined with contact lenses are increasingly used for slowing axial elongation in progressive myopia in children aged 6–18 years.

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3. Contact Lens Fitting in Post-Refractive Surgery Eyes

🔬 Common Refractive Surgeries

• LASIK (Laser-Assisted in Situ Keratomileusis)
• PRK (Photorefractive Keratectomy)
• RK (Radial Keratotomy)
• SMILE (Small Incision Lenticule Extraction)

📉 Optical Issues After Surgery

• Irregular astigmatism
• Central flattening or decentered ablation
• Night glare, halos, ghosting
• Dryness and corneal instability

✅ Role of Contact Lenses

• Improve quality of vision in irregular corneas
• Address under-correction or regression
• Relieve dryness symptoms

👓 Lens Types for Post-Surgical Eyes

• Large-diameter RGP: Vault over irregular zones
• Scleral lenses: Best for highly irregular corneas or dryness
• Hybrid lenses: RGP center with soft skirt for comfort
• Custom soft lenses: Mild irregularities, or patients intolerant to RGP

🔧 Fitting Guidelines

• Base curve often needs to match mid-peripheral cornea, not just central K-reading
• Trial lens fitting is essential due to unique corneal shape
• Use topography or OCT maps to guide lens selection
• Refit periodically as post-op healing continues for 6–12 months

📝 Follow-Up Care

• Frequent reviews to monitor for corneal haze or epithelial breakdown
• Check for lens-induced dryness or compression
• Educate patient on handling, as lens types are often more complex

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Conclusion

Specialty lens fitting is a vital skill in optometric practice, allowing vision correction and ocular surface protection in complex cases such as aphakia, pediatric anomalies, and post-refractive surgery eyes. These patients require customized lens design, vigilant follow-up, and careful counseling. Mastery of specialty fitting protocols ensures optimal outcomes in both vision and ocular health.

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References

1. Bennett ES, Henry VA. Clinical Manual of Contact Lenses, 3rd Edition, Lippincott Williams & Wilkins, 2008.
2. Phillips AJ, Speedwell L. Contact Lenses, 5th Edition, Butterworth-Heinemann, 2007.
3. Walline JJ et al. Pediatric Contact Lens Fitting, AOA Clinical Guidance.
4. American Academy of Optometry. Specialty Lens Practice Reports, 2022.

Management of Presbyopia with Contact Lenses

Introduction

Presbyopia is an age-related physiological condition characterized by a gradual loss of the eye's ability to focus on near objects. It typically becomes symptomatic between the ages of 40 and 45. While reading glasses are the traditional solution, many patients now seek contact lens-based options that offer convenience, cosmetic appeal, and functional vision at all distances.

Understanding Presbyopia

• Due to loss of elasticity in the crystalline lens and weakening of the ciliary muscles
• Affects both emmetropic and ametropic individuals
• Symptoms include blurred near vision, eye strain, and difficulty reading small print

Goals of Contact Lens Correction in Presbyopia

• Provide functional vision at near, intermediate, and distance ranges
• Minimize dependence on reading glasses
• Ensure visual comfort and binocular balance
• Preserve contrast sensitivity and reduce ghosting or halos

Options for Presbyopic Contact Lens Correction

1. Monovision

• Dominant eye corrected for distance; non-dominant eye corrected for near
• Brain adapts to use each eye for its intended task
• Inexpensive and uses standard single-vision lenses
• Pros: Easy to fit, widely accepted
• Cons: Reduces stereopsis and depth perception
• Ideal for early presbyopes or patients with high adaptability

2. Modified Monovision

• Distance correction in dominant eye; multifocal or low add lens in non-dominant eye
• Combines benefits of monovision and multifocal
• Used when full monovision causes discomfort or imbalance

3. Bifocal/Multifocal Contact Lenses

• Designs that provide simultaneous or alternating vision at multiple focal points
• Simultaneous Vision: Both distance and near images fall on the retina; brain selects relevant image
• Alternating (Translating) Designs: Eye movement shifts lens zones for near or distance

Types of Multifocal Designs

• Concentric Rings: Distance center or near center with alternating rings
• Aspheric Designs: Gradual change in power from center to periphery
• Hybrid Designs: RGP center for optics and soft skirt for comfort
• Scleral Multifocals: For irregular corneas with presbyopia

Materials and Modalities

• Available in soft (daily, biweekly, monthly), RGP, and hybrid materials
• Popular brands: Biofinity Multifocal, Air Optix Multifocal, Acuvue Oasys for Presbyopia, PureVision Multifocal

Patient Selection and Education

• Assess patient motivation and lifestyle needs
• Discuss pros and cons of each method clearly
• Explain adaptation period—especially for multifocals
• Conduct eye dominance test before prescribing monovision
• Consider trial lenses and real-world testing

Fitting Considerations

• Perform accurate refraction and add power calculation
• Start with low add and increase only as needed
• Evaluate both vision and subjective comfort
• Ensure centration and movement of the lens is optimal
• Check binocular vision performance

Managing Patient Expectations

• Not all patients achieve 20/20 at all distances
• Explain visual compromise and adaptation time
• Reinforce regular follow-up visits for assessment
• Offer combination strategies if needed (e.g., reading glasses over multifocals)

Advantages and Limitations

• Advantages:
  • Greater freedom from spectacles
  • Improved self-image and aesthetics
  • Better field of view than reading glasses
• Limitations:
  • Requires adaptation period
  • May compromise contrast or clarity in low light
  • Cost may be higher than traditional lenses

Conclusion

Presbyopic contact lens correction offers a modern, non-surgical alternative for patients seeking visual freedom. Understanding the optical principles, proper lens selection, patient lifestyle, and follow-up care are crucial for success. With various options like monovision, multifocal, or modified monovision, contact lenses can restore near and distance vision while meeting patient expectations and comfort.

References

1. Phillips AJ, Speedwell L. Contact Lenses, 5th Edition, Butterworth-Heinemann, 2007.
2. Bennett ES, Henry VA. Clinical Manual of Contact Lenses, 3rd Edition, Lippincott Williams & Wilkins, 2008.
3. American Academy of Optometry. Presbyopia Correction Guidelines.
4. BCLA Clinical Practice Recommendations – Presbyopia, 2022.