A 62-year-old man with myopia (−5.00 D) and presbyopia undergoes cataract surgery. He desires spectacle independence for both distance and near vision. Which IOL design feature best distinguishes an extended depth of focus (EDOF) IOL from a traditional bifocal diffractive multifocal IOL in achieving this goal?

Explanation

## Extended Depth of Focus (EDOF) vs. Bifocal Multifocal IOLs ### EDOF IOL Design - Uses **modified wavefront optics** or **refractive design** (e.g., Tecnis Symfony, Vivity) - Creates a **continuous, elongated focal range** from distance through intermediate to near - Light is shaped to extend depth of focus rather than split into discrete points - Provides smooth, uninterrupted vision across all distances - Minimal light loss; better contrast sensitivity than traditional multifocals ### Bifocal Diffractive Multifocal IOL - Uses **concentric diffractive zones** (e.g., ReSTOR, Alcon AcrySof) - Splits light into **two discrete focal points** (distance and near) - Creates a **gap at intermediate distances** (30–60 cm) with blurred vision - Greater light loss due to splitting; more halos and glare - Older technology, but proven long-term safety **Key Point:** The fundamental distinction is **continuous vs. discrete** focal range. EDOF provides a smooth spectrum of vision; bifocal multifocals have a "sweet spot" at distance and near with a functional gap in between. ### Comparison Table | Feature | EDOF IOL | Bifocal Multifocal | | --- | --- | --- | | **Focal range** | Continuous (distance → intermediate → near) | Discrete (distance + near with gap) | | **Intermediate vision** | Excellent | Blurred (30–60 cm zone) | | **Contrast sensitivity** | Excellent | Reduced | | **Halos/glare** | Minimal | Moderate to significant | | **Light efficiency** | Higher | Lower (light split) | | **Cost** | Higher | Moderate | | **Spectacle dependence** | Very low | Low | **High-Yield:** EDOF IOLs are increasingly preferred for patients who spend significant time at intermediate distances (computer work, dashboard viewing) because they eliminate the intermediate vision gap that frustrates bifocal multifocal users. **Clinical Pearl:** In the patient described (myopic, presbyopic, seeking spectacle independence), an EDOF IOL would be superior to a bifocal multifocal because the continuous intermediate vision range aligns with his lifestyle needs and reduces the risk of visual dissatisfaction.