6.2 Medical History, Diseases, Medications & Allergies

6.2 Medical History, Diseases, Medications & Allergies

Quick Answer: The prefitting medical history targets systemic conditions and drugs that change the ocular surface. Diabetes reduces corneal sensitivity and healing; thyroid disease and Sjogren's syndrome cause dry eye; isotretinoin (Accutane) is an absolute contraindication because it causes severe dry eye. Antihistamines, beta-blockers, decongestants, and oral contraceptives reduce tear volume. Pregnancy, age extremes, and ocular allergies modify lens choice. Document each before fitting.

Why Systemic History Determines CL Success

The cornea is avascular and depends on the tear film for oxygen, nutrients, and immune defense. Any systemic condition or drug that alters tears, lids, innervation, or immunity changes the safety profile of a contact lens. The CLRE blueprint expects candidates to identify which conditions and medications modulate — or prohibit — lens wear.

Systemic Diseases That Affect Contact Lens Wear

Alcohol, Recreational Drugs & Contact Lens Wear

Domain I pathology also expects recognition of substance-related ocular effects:

Ask nonjudgmentally during history. A patient who wears lenses while intoxicated or who uses recreational drugs may present with solution noncompliance, case contamination, or delayed reporting of pain — classic CLRE red flags.

Diabetes — A High-Yield Exam Topic

Diabetic patients have reduced corneal sensitivity (diabetic neurotrophic keratopathy) and delayed epithelial healing. A small abrasion that a non-diabetic patient heals overnight may persist for days in a diabetic, escalating to microbial keratitis. Fitting principles:

• Use high-Dk silicone hydrogel or RGP/scleral lenses to maximize oxygen
• Avoid extended wear — overnight hypoxia compounds healing risk
• Shorter wearing time with gradual build-up
• More frequent follow-up in the first month
• Counsel the patient that any red, painful eye is an immediate remove-and-call event

Thyroid Disease

Both hyperthyroid (Graves') and hypothyroid states affect the ocular surface. Graves' ophthalmopathy causes lid retraction, lagophthalmos, and exophthalmos — the exposed cornea dries, especially at night. Hypothyroidism reduces tear production. Fitting principles:

• Avoid extended wear (already compromised nocturnal protection)
• Use lubricating drops and ointment at bedtime
• Consider scleral lenses for severe exposure — they vault the cornea and hold a fluid reservoir
• Monitor for exposure keratopathy at follow-up

Medications and Contact Lens Wear

The Isotretinoin Rule — Absolute Contraindication

Isotretinoin (Accutane) causes severe, persistent dry eye through meibomian gland atrophy and reduced aqueous tear production. It is also highly teratogenic. The standard of care is to defer contact lens fitting until at least 6 months after discontinuation and tear function has normalized. Some references require Schirmer and TBUT normalization before fitting. The exam may present a patient on isotretinoin requesting lenses — the correct answer is to defer, not to fit with a dry-eye lens.

Allergies and Contact Lens Wear

Allergic history is critical because allergy both reduces tolerance and dictates care-system choice.

• Seasonal / perennial allergic conjunctivitis — fit during a quiescent period; daily disposable preferred; prescribe allergy drops (antihistamine/mast-cell stabilizer) if needed.
• Giant papillary conjunctivitis (GPC) history — daily disposable or RGP (less mechanical trauma); avoid soft lenses with high lipid deposition; consider mast-cell stabilizer.
• Solution preservative allergy (thimerosal, chlorhexidine) — switch to preservative-free or hydrogen peroxide systems; daily disposables eliminate solution exposure entirely.
• Pollen / environmental allergy — counsel that symptoms worsen in spring; cool compresses; daily disposable.

Special Populations

Pediatric Patients

Pediatric fits are usually therapeutic (aphakia, anisometropic amblyopia, keratoconus, orthokeratology for myopia control). Parental supervision is required for insertion, removal, and hygiene. Children often tolerate lenses well and have robust tears, but the fitter must train the parent and document competence.

Presbyopic Patients (>40 years)

Presbyopia requires a modality decision:

• Multifocal soft lenses — simultaneous vision design; Convenience vs. contrast sensitivity tradeoff
• Monovision — one eye distance, one eye near; high success rate but reduces stereopsis and contrast
• Modified monovision — multifocal in dominant eye, single-vision near in non-dominant
• RGP bifocals / scleral multifocals — better optics for high astigmatism or irregular corneas

Geriatric Patients (>65 years)

Reduced tear production, lid laxity, and decreased manual dexterity are common. Daily disposable lenses with insertion/removal aids, large-handle tweezers, and a stable wearing schedule are often the best choice.

Pregnancy and Lactation

Pregnancy causes hormonal fluid retention, corneal curvature steepening (myopic shift), reduced tear production, and immunologic modulation. Existing lens wearers may develop intolerance. Fitting new lenses during pregnancy is generally deferred until several weeks postpartum or after lactation, when the refraction and tear film stabilize. Any fit during pregnancy should use daily disposables with conservative wearing time and close follow-up. Isotretinoin and tetracycline-class drugs are also contraindicated in pregnancy — a double reason to defer.

Key Takeaways

• Diabetes reduces corneal sensitivity and healing — fit with high-Dk lenses, no extended wear, close follow-up
• Isotretinoin (Accutane) is an absolute contraindication — defer 6 months post-discontinuation
• Antihistamines, decongestants, beta-blockers, oral contraceptives, SSRIs all reduce tear volume — modulate lens and care regimen
• Pregnancy steepens the cornea and dries the tear film — defer new fits until postpartum
• GPC and preservative allergy favor daily disposables or preservative-free hydrogen peroxide systems