Perfect vision occurs when light rays converge at a point on the retina and for those whose vision requires aid, special lenses are used to refocus the light rays. While recent technological advances have produced many options for treating most common vision impairments: Myopia (nearsightedness) hyperopia (farsightedness) and astigmatism (a defect in the eye), they can also be treated with corrective lenses. Following are some of the questions that Dr. Hajra Salar, Ophthalmologist based in Jeddah, has answered on correcting vision impairments:
What is the cause for refractive errors?
Refractive errors are thought to occur due to a combination of genetic and environmental factors. Trauma or ocular disorders such as keratoconus may induce refractive errors.
How can refractive errors be overcome?
Refractive errors can be overcome by either using temporary aids such as glasses and contact lenses or permanently by undergoing a refractive surgical procedure such as LASIK.
What are the kinds of frames and lenses?
Eyeglass frames are commonly made from metal or plastic. Lenses were originally made from glass, but many are now made from various types of plastic including CR-39 or polycarbonate. These materials reduce the danger of breakage and weigh less than glass lenses. Options that you can have on your lenses:
• Scratch-resistant coatings — that can be applied to most plastic lenses giving them similar scratch resistance to glass.
• Anti-reflective coatings — intended to improve night vision and make the wearer’s eyes more visible.
• Polycarbonate lenses — the lightest and most shatter-resistant, making them the best for impact protection, yet offering poor optics due to high dispersion.
• CR-39 lenses — the most common plastic lenses due to their light weight, high scratch resistance and low transparency for ultra-violet and infrared radiation.
What are contact lenses?
They are small plastic lenses fitted to the size and shape of a patient’s cornea, floating over the tear film layer.
Why are contact lenses used?
They are used to correct refractive errors such as nearsightedness, farsightedness and corneal astigmatism. Special lenses are available for keratoconus. Also therapeutic contact lenses are used for various eye diseases. Some people use colored contact lenses for cosmetic purposes.
How are contact lenses fitted?
After thorough examination of the eye, the best lens for an individual’s eye is advised. Various types of lenses include rigid (hard), rigid gas permeable (semi-soft), soft, toric (has two different curves instead of one), extended wear and disposable lenses. A series of trial lenses may also be used in determining the best size and fit before your custom-made lenses are ordered.
Are contact lenses safe?
Yes, they are, although one has to be careful with the handling and care of the lens.
At what age can one start using contact lenses?
They can be used at any age as long as the wearer is able to take care of the lens. Usually we expect teens to be mature enough to handle the lenses well.
— Dr. Hajra Salar, Ophthalmologist based in Jeddah