Drug-Induced Cataracts

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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

DrugMechanismCataract TypeKey Notes
Corticosteroids?Lens metabolism ↓, Na-K ATPase ↓, oxidative damagePosterior Subcapsular (PSC) classic, Ant. SCDose/duration dependent (Prednisolone >10-15 mg/day >1 yr). All routes. 📌 Steroids → Subcapsular (PSC).
PhenothiazinesPhotosensitization, melanin bindingAnt. capsular/subcapsular pigment deposits (stellate)Dose-related (Chlorpromazine >300 mg/day). Brownish granules.
Miotics (strong)Long-term use, ?cholinergic effect on lensAnt. subcapsular vacuoles/opacitiesEsp. irreversible anticholinesterases (e.g., Echothiophate).
AmiodaroneDrug deposition in lens epitheliumAnt. subcapsular yellowish-brown deposits, spoke-likeDose >200 mg/day. Cornea verticillata. Rarely ↓ vision.
BusulfanDirect lenticular toxicityPSC, corticalAlkylating agent (CML, BMT).
Gold SaltsGold deposition (lens chrysiasis)Ant. capsular fine yellow/gold particlesRheumatoid Arthritis. Rarely ↓ vision.
Allopurinol?Xanthine oxidase inhibition effectCortical, PSCEvidence less robust.

⭐ 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.

Slit-lamp view of posterior subcapsular cataract

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.

Practice Questions: Drug-Induced Cataracts

Test your understanding with these related questions

A 45 year old male, known case of Rheumatoid arthritis is on a monotherapy since many years. Symptoms of RA are controlled but suddenly patient develops blurring of vision. Which of the following drug is responsible for sudden effect on vision?

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Flashcards: Drug-Induced Cataracts

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What is the rx of choice for after cataract?_____

TAP TO REVEAL ANSWER

What is the rx of choice for after cataract?_____

Nd:Yag laser posterior capsulotomy

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