Drug-Induced Cataracts

Introduction - Pharma's Foggy Lens

• Drug-induced cataracts (DIC): Lens opacities caused by systemic or topical medications, a key iatrogenic factor.
• Impact: Significant visual morbidity; often preventable or reversible if drug is discontinued early.
• General Pathophysiology:
  • ↑ Oxidative stress on lens structures.
  • Direct drug toxicity to lens epithelial cells.
  • Altered lens protein integrity, leading to aggregation.
  • Osmotic dysregulation within the lens.
• Major implicated drug classes include corticosteroids, phenothiazines, amiodarone, and miotics.

⭐ Corticosteroids are the most common cause of drug-induced cataracts, typically presenting as posterior subcapsular opacities (PSC).

Causative Drugs - Pills & Potions

⭐ Corticosteroids are the most common cause of drug-induced cataracts, classically presenting as Posterior Subcapsular Cataracts (PSC).

Clinical Features - Spotting the Haze

• Symptoms:
  • Painless, progressive ↓ vision.
  • Glare, especially with bright lights or night driving.
  • Difficulty with reading or near tasks.
  • Monocular diplopia (less common).
• Signs (Slit-Lamp Examination is Key):
  • Visual acuity: Variable; often worse in bright light with PSC.
  • Red reflex: May show dark opacities against the orange-red glow.
  • Posterior Subcapsular Cataract (PSC):
    • Classic for steroid use.
    • Appears as iridescent granules, breadcrumb-like opacities, or dense plaques on the posterior capsule.
  • Anterior Subcapsular Opacities:
    • Miotics (e.g., pilocarpine): Vacuoles, small discrete opacities.
    • Phenothiazines (e.g., chlorpromazine): Fine, yellowish-brown granules, sometimes stellate pattern.
    • Amiodarone: Anterior capsular and subcapsular deposits.

⭐ Exam Favourite: Corticosteroids typically induce Posterior Subcapsular Cataracts (PSC), which significantly impair vision, especially in bright light, due to their location near the nodal point of the eye.

Management - Clearing the View

• Prevention First:
  • Minimize dose & duration of cataractogenic drugs (e.g., steroids, phenothiazines, amiodarone, miotics).
  • Regular eye exams for patients on long-term high-risk medications.
• Drug Adjustment:
  • Attempt to stop or taper the causative drug; always consult prescribing physician.
  • Early cataracts (esp. steroid-induced) may stabilize or partially regress.
• Surgical Solution:
  • Phacoemulsification with IOL implantation for visually significant cataracts impacting daily life.
  • Prognosis generally excellent post-surgery.

⭐ Steroid-induced cataracts typically present as posterior subcapsular opacities (PSC). These often cause disproportionate glare and near vision issues relative to Snellen acuity.

High‑Yield Points - ⚡ Biggest Takeaways

• Corticosteroids are the most common cause, especially topical and systemic long-term use.
• Typically cause Posterior Subcapsular Cataract (PSC).
• PSC appears as opacities at the posterior pole of the lens, causing early glare.
• Phenothiazines (e.g., chlorpromazine) cause anterior capsular/subcapsular pigment deposits.
• Amiodarone can cause anterior subcapsular stellate (star-shaped) opacities.
• Miotics (e.g., pilocarpine) rarely cause anterior subcapsular vacuoles with prolonged use.
• Cataract formation is often dose-dependent and duration-dependent for most drugs.