Description

The 20D Large Lens is an essential tool for ophthalmologists, designed for use with binocular indirect ophthalmoscopes (BIO). Renowned for its precision, this lens is manufactured by leading companies such as Volk and Ocular Instruments, offering exceptional quality for detailed retinal examinations.

Key Features

• Optical Design: The lens features double aspheric glass optics, providing superior image quality with minimal aberrations. This design ensures clear visualization of the retina, crucial for accurate diagnosis.
• Dioptric Power: With a power of +20 diopters, the lens offers a balanced combination of magnification and field of view, making it ideal for both adult and pediatric examinations.
• Field of View: The lens provides a field of view ranging from 46° to 60°, depending on the manufacturer, allowing comprehensive examination of the central retina.
• Image Magnification: Approximately 3x magnification enables detailed observation of retinal structures, while the inverted image orientation is standard for this type of lens.

Practical Benefits

• Working Distance: A 50 mm working distance facilitates comfortable use, allowing easy manipulation during examination.
• Material and Design: The lens is encased in a metal ring, available in various colors, enhancing durability and handling. Customization options include engraving on the lens and case.
• Included Accessories: Comes with a complimentary single-lens case for secure storage.

Clinical Applications

The 20D Large Lens is primarily used for general retinal examinations, central retinal and optic disc evaluation, and is particularly beneficial for patients with nystagmus or those requiring scleral indentation. Its design allows for effective estimation of optic disc size and provides a comprehensive view up to the mid-peripheral region of the retina.

Optical Performance

Compared to higher dioptric power lenses, the 20D lens offers greater magnification with a narrower field of view. It is expertly corrected for astigmatism, aberrations, field curvature, and coma, ensuring high-quality imaging. This lens is not typically used with slit lamps, as other lenses like +78D or +90D are more suitable for that purpose.

Maintenance and Care

Proper cleaning and maintenance are vital for the longevity of the lens. It should be manually cleaned with alcohol wipes and disinfected according to regulatory guidelines. Compatible disinfection methods include glutaraldehyde solutions and approved medical disinfectant wipes. Sterilization should be performed using ethylene oxide or compatible low-temperature systems, avoiding steam autoclaving or boiling.

Storage and Inspection

Store the lens at room temperature in a clean, dry environment. Regular inspection for damage is recommended before each use to ensure optimal performance and safety.