The Evolution of Vision: A Look into Contact Lens Manufacturing
Contact lenses have revolutionized vision correction, offering an alternative to traditional eyeglasses. Since their commercial production began in the 1970s, advancements have led to two primary types: rigid hard lenses and flexible soft lenses, each with distinct manufacturing processes and benefits.
Crafting Hard Lenses: Precision and Customization
Hard contact lenses are characterized by their rigid structure and bespoke fit, meticulously designed for an individual’s eye. The manufacturing journey involves:
- Eye Measurement: Utilizing a carat graph, the patient’s eyes are precisely measured. This accounts for the microscopic irregularities of the cornea, ensuring a perfect fit.
- Material Preparation: Lenses begin as plastic sticks, loaded into a grinding machine.
- Initial Shaping: Computer-controlled diamond grinders mill the lens’s diameter and shape the inside to match the unique pattern of the patient’s eye.
- Cutting and Prescription Application: Once shaped, the lens is cut from the rod. It’s then glued to a stud and mounted for further grinding. A diamond drill, guided by the patient’s eye prescription, passes over the outside of the lens twice—first for the correct thickness, then for the exact curvature.
This intricate process ensures that each hard lens provides clear vision, tailored to the wearer’s specific needs.
Innovating Soft Lenses: Comfort and Convenience
Soft contact lenses offer a more adaptable and convenient option, conforming to the eye’s surface. Their production involves a different set of steps:
- Liquid Base: The process starts with a plastic liquid. A blue dye is often added to help users locate dropped lenses.
- Molding and Baking: This mixture is poured into plastic molds, covered, and baked at 97°C for 10 minutes.
- Quality Check: Each lens is inspected for scratches and cracks while still rigid.
- Hydration and Softening: To achieve their characteristic softness, the lenses are placed in a saline solution, allowing them to absorb liquid.
- Sterilization and Tints: After sterilization with heat, the lenses are ready. For those desiring a change in eye color, soft lenses can be dipped in dye, offering a variety of tints.
Soft lenses, often disposable, provide a comfortable and versatile solution for many contact lens wearers.
Vocabulary Table
| Term | Definition | Used in sentence |
|---|---|---|
| Contact Lenses | Small corrective lenses worn on the surface of the eye. | Since their commercial production began in the 1970s, contact lenses have revolutionized vision correction. |
| Short-sighted | Unable to see distant objects clearly; myopia. | If you were short-sighted, your choice was pretty much the shape and color of your frames. |
| Long-sighted | Unable to see near objects clearly; hyperopia. | If you were long-sighted, your choice was pretty much the shape and color of your frames. |
| Rigid | Unable to bend or be forced out of shape; stiff. | Hard lenses are rigid and are designed to fit an individual eye perfectly. |
| Microscopic level | A level of detail only visible with a microscope. | Although eyes might appear to be perfectly smooth, on a microscopic level they have an irregular surface. |
| Irregular surface | A surface that is not smooth or even. | On a microscopic level, eyes have an irregular surface, as unique as your fingerprints. |
| Diamond grinder | A tool with industrial diamonds used for precision grinding. | The diamond grinder mills out the lens’s diameter and shapes the inside. |
| Curvature | The curving or bending of something. | The diamond drill passes over the outside of the lens for the exact curvature. |
| Saline solution | A solution of salt in water, typically for medical use. | Each soft lens is placed in a saline solution where they absorb the liquid, making them soft. |
| Sterilized | Made free from bacteria or other living microorganisms. | Once sterilized with a further blast of heat, they’re ready. |
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Fill in the Blanks Exercise
1. Since their commercial production began in the 1970s, have revolutionized vision correction.
2. If you were , your choice was pretty much the shape and color of your frames.
3. If you were , your choice was pretty much the shape and color of your frames.
4. Hard lenses are and are designed to fit an individual eye perfectly.
5. Although eyes might appear to be perfectly smooth, on a they have an irregular surface.
6. On a microscopic level, eyes have an , as unique as your fingerprints.
7. The mills out the lens’s diameter and shapes the inside.
8. The diamond drill passes over the outside of the lens for the exact .
9. Each soft lens is placed in a where they absorb the liquid, making them soft.
10. Once with a further blast of heat, they’re ready.
Vocabulary Quiz
