How do aspheric lenses become a powerful optical tool for wide field of view and stereoscopic imaging?
Publish Time: 2026-01-31
In ophthalmic clinical examinations, clear and comprehensive observation of fundus structures—such as the retina, optic nerve head, macula, and retinal vessels—is crucial for the early diagnosis of diseases such as diabetic retinopathy, glaucoma, and macular degeneration. As a core optical element in modern fundus examination, aspheric lenses, with their unique aspheric design and high-performance materials, when used in conjunction with indirect ophthalmoscopy or slit-lamp microscopes, can present high-quality images with a wide field of view, magnified images, strong stereoscopic effect, and without contact with the cornea, greatly improving the efficiency and accuracy of diagnosis.
1. Aspheric Design Overcomes Traditional Optical Limitations
Traditional spherical lenses are prone to spherical aberration in the peripheral regions, leading to blurred and distorted images at the edges, limiting the effective field of view. Aspheric lenses, through precisely calculated curvature changes, ensure that light rays, regardless of whether they enter from the center or the edge, converge precisely to the same focal plane. This design significantly reduces aberrations and expands the usable field of view, allowing doctors to cover a wider area of the retina in a single observation, particularly facilitating the observation of peripheral retinal and posterior pole structures. Simultaneously, the aspherical structure optimizes the optical path and enhances depth of field, enabling different layers of fundus tissue to present a clear depth relationship in the image, thus giving the image a strong sense of three-dimensionality and aiding in the identification of three-dimensional morphological changes such as optic disc cupping, macular bulging, or retinal detachment.
2. High Magnification and Wide Field of View Synergistically Enhance Detail Recognition
The "78" in 78D lens represents its optical power of approximately 78 diopters. When used with a slit-lamp microscope, it achieves an intermediate image magnification of approximately 1.08 times. Further magnification through the eyepiece results in an overall magnification sufficient to clearly distinguish micron-level fundus details, such as early pathological changes like capillary hemangiomas, microaneurysms, and hard exudates. More importantly, this magnification does not come at the expense of the field of view—the aspherical technology achieves a synergistic optimization of "large image + wide field of view." Doctors can complete a systematic scan of the macula, optic disc, and peripheral retina in a single, stable observation without frequently moving the lens or adjusting the patient's gaze, significantly improving examination efficiency and comfort.
3. Non-contact examination ensures safety and comfort
The 78D lens uses a non-contact operating mode, requiring only a few centimeters in front of the patient's eyes during examination. Unlike direct ophthalmoscopy, it does not need to be close to the cornea, nor does it require the coupling gel needed for contact lenses. This not only avoids the risk of cross-infection and corneal epithelial damage but also significantly improves patient cooperation, making it especially suitable for children, sensitive individuals, or post-operative patients. Simultaneously, the operator can maintain a natural sitting posture and freely adjust the slit lamp parameters with both hands, achieving more stable and sustained observation.
4. High-quality optical materials and coating technology ensure image purity
This lens is made of high-transmittance optical glass, with a visible light transmittance exceeding 95%, ensuring maximum light entry into the fundus and reflection back to the imaging system. Featuring a multi-layered, high-reflection coating, it effectively suppresses surface reflection and internal stray light, significantly improving image contrast and color reproduction, making retinal vessels appear vividly red, optic disc boundaries clear and sharp, and the foveal reflection point clearly visible. Furthermore, the lens surface is coated with a waterproof and stain-resistant protective layer, preventing fingerprints, moisture, or disinfectant residue from adhering during daily use, making cleaning easy and unaffected by optical performance. The lens structure is robust, wear-resistant, and impact-resistant, suitable for high-frequency clinical use environments.
Aspheric lenses seamlessly adapt to mainstream slit-lamp microscopes and indirect ophthalmoscopy systems, becoming standard equipment in ophthalmology clinics, fundus screening, and teaching training. Their stable optical performance and user-friendly design allow beginners to quickly master fundus examination techniques, while experienced physicians can use them to detect subtle lesions and develop precise treatment plans.
In summary, aspheric lenses, through their four core advantages of aspherical optical design, high-transmittance materials, advanced coatings, and non-contact operation, successfully solve the pain points of traditional fundus examinations, such as narrow field of view, weak stereoscopic vision, and inconvenient operation. They provide ophthalmologists with a pair of eyes that can "see wider, clearer, and deeper," truly achieving an efficient, safe, and accurate visual fundus diagnosis and treatment experience.
