In phacoemulsification, which ultrasonic frequency range is most commonly used for nucleus fragmentation and emulsification?

Explanation

## Ultrasonic Frequency in Phacoemulsification **Key Point:** Modern phacoemulsification machines most commonly operate at frequencies between **20–30 kHz** (20,000–30,000 cycles per second). This is the standard frequency range used in the vast majority of commercially available phacoemulsification systems worldwide, including the Alcon Infiniti, AMO Signature, and Bausch & Lomb Stellaris platforms. ### Frequency Ranges and Clinical Implications | Frequency Range | Characteristics | Clinical Use | |---|---|---| | **20–30 kHz** | **Standard range; optimal mechanical cavitation and jackhammer effect** | **Most commonly used; efficient nucleus fragmentation** | | 40–50 kHz | Higher frequency; used in some torsional/rotational systems (e.g., Ozil at ~32 kHz) | Less common; reduced longitudinal stroke | | 60–70 kHz | Very high frequency; reduced emulsifying power | Rarely used clinically | | 80–100 kHz | Ultrahigh frequency | Not used for phacoemulsification | **High-Yield:** The 20–30 kHz range is the established standard because: 1. It produces effective **cavitation** and **jackhammer (mechanical)** effects that fragment the cataractous nucleus 2. The longitudinal stroke amplitude at this frequency is sufficient to emulsify even dense (grade 4+) nuclei 3. It is the frequency range specified in standard ophthalmology references including **Kanski's Clinical Ophthalmology** and **Yanoff & Duker's Ophthalmology** **Clinical Pearl:** Torsional phacoemulsification (Ozil technology, Alcon) operates at approximately **32 kHz** with a rotational rather than longitudinal tip motion, reducing heat generation and improving efficiency — but this is still within the 20–30 kHz neighborhood, not 40–50 kHz. **Mnemonic:** **20–30 kHz = PHACO STANDARD** — this is the frequency range cited in all major ophthalmic surgery textbooks (Kanski, Yanoff & Duker, AAO BCSC Section 11) for conventional phacoemulsification. --- *Reference: Kanski's Clinical Ophthalmology, 9th ed.; Yanoff & Duker Ophthalmology, 5th ed., Chapter on Cataract Surgery.*