Reading glasses

Figure 1

Regular progressive glasses with a large reading addition function well in reading at the computer screen, when the screen is placed lower than the desk surface and at a comfortable distance. The working distances are measured before selecting the lenses. Nearly every manufacturer has a progressive lens with a large reading addition.

Figure 2

These glasses look similar to the glasses in Figure 1 but the structure of the lenses is different. They are specially made for work in an ophthalmologist's office where the doctor must look straight ahead at the patient's eyes and thus there must be a reading add for this 50-70cm (about 2 feet) distance at the level of the doctor's pupils. The doctor must also see the visual acuity chart at several meters' distance so there is a small area for distance vision high up on the lens. Lenses like these function well at home, at computer terminals, in all tasks that require reading acuity in a large area. - I use these glasses often when walking to or from my office but driving a car would be uncomfortable.

Figure 3a

Small frames cause problems in near work if the area to be seen is as large as in office work. The frame cuts much of the reading part of the lens and everything closer than the point marked on the picture is blurred if the person is farsighted. Tilting the frame more than usually improves the situation a little but not enough (Figure 3b).

Figure 3b

Glasses should preferably have such a frame that the distance from the eye is small and the frame should be fitted so that the line of sight is perpendicular to the surface of the lens. The size of the frame must allow large enough a field of vision through the lens (except when the person is suitably nearsighted and looks below the frame when reading). Too small frames force the user to nod, too large frames are too far from the eyes, touch the skin and may cause irritation or allergic reactions and get foggy during winter. A good frame leaves a space between the frame and the skin as wide as the person's little finger is thick.

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