As in keratometer measurements, there may be two basic reasons giving rise to the display of the "Error" message:
The results of the five internal individual measurements vary by more than 0.15 mm (very rare) or
The produced images (optical sections) do not contain relevant structures (normally, the edge of the crystalline lens), or disturbances are preventing their detection.
Eyes that cannot be measured:
Aphakic eyes cannot be measured, as the calculation of the anterior chamber depth is based on the evaluation (distance measurement) of the image of the optical section.
The same refers to pseudophakic eyes, if the intraocular lens does not sufficiently scatter the light from the slit.
Under certain circumstances, a strong reflection may be visible on pseudophakic eyes, which is produced by the rear surface of the lens.
When you release an anterior-chamber depth measurement in such a case, the evaluation software will interpret the bright reflection as the front fusca of the crystalline lens. The instrument will then display a measured value in the range of about 5 to 6 mm. This value is not the exact anterior chamber depth!
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Cataracts are classified as one of three types: a nuclear cataract is most commonly seen as it forms. This cataract forms in the nucleus, the center of the lens, and is due to natural aging changes. A cortical cataract, which forms in the lens cortex, gradually extends its spokes from the outside of the lens to the center. Many diabetics develop cortical cataracts. A sub-capsular cataract begins at the back of the lens. People with diabetes, high farsightedness, retinitis pigmentosa or those taking high doses of steroids may develop a sub-capsular cataract. Cataract symptoms cataract starts out small, and at first has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass or viewing an impressionist painting. A cataract may make light from the sun or a lamp seem too bright or glaring. Or you may notice when you drive at night that the oncoming headlights cause more glare than before. Colors may not appear as bright as they once did. The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. When a nuclear cataract first develops it can bring about a temporary improvement in your near vision, called second sight. Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens. Meanwhile, a sub-capsular cataract may not produce any symptoms until it's well developed. If you think you have a cataract, see an eye doctor for an exam to find out for sure. What causes a cataract? No one knows for sure why the eye's lens changes as we age, forming cataracts. Researchers are gradually identifying factors that may cause cataracts — and information that may help to prevent them. Many studies suggest that exposure to ultravlens implantet light is associated with cataract development, so eye care practitioners recommend wearing sunglasses and a wide-brimmed hat to lessen your exposure. 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A small study published in 2002 found lead exposure to be a risk factor; another study in December 2004, of 795 men age 60 and older, came to a similar conclusion. But larger studies are needed to confirm whether lead can definitely put you at risk, and if so, whether the risk is from a one-time dose at a particular time in life or from chronic exposure over years. Cataract treatment when symptoms begin to appear, you may be able to improve your vision for a while using new glasses, strong bifocals, magnification, appropriate lighting or other visual aids. Think about surgery when your cataracts have progressed enough to seriously impair your vision and affect your daily life. Many people consider poor vision an inevitable fact of aging, but Expert witness cataract eye surgery is a simple, relatively painless procedure to regain vision. Expert witness cataract eye surgery is very successful in restoring vision. 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Greater than 95% of those patients now enjoy improved vision. State-of-the-art Expert witness cataract eye surgery is now a safe, effective, and comfortable procedure performed almost exclusively on an outpatient basis. Most cataract surgeries are now performed using microscopic size incisions, advanced ultrasonic equipment to fragment cataracts into tiny fragments, and foldable intraocular lenses (lens implants) to maintain small incision size. Expert witness.
When you release an anterior-chamber depth measurement in such a case, the evaluation software will interpret the bright reflection as the front fusca of the crystalline lens. The instrument will then display a measured value in the range of about 5 to 6 mm. This value is not the exact anterior chamber depth!
