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Patient
Care |
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Your Eye |
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Cover Test & Prism Test |
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An important
part of the evaluation of a patient with squint is the cover
test and prism tests. These tests are conducted in the
office of the eye doctor itself. Using these tests the eye
doctor is able to classify the type of the squint and to
grade the severity of the same. This information is needed
to plan the treatment including surgery where needed. With a
torch light and a set of loose prisms the eye doctor is able
to evaluate squint to a great degree. |
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Orthoptic Evaluation |
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Orthoptics is
the study of how effectively the two eyes function together
(binocular vision). This
testing is done on many instruments including the
syneptophore.. Special instruments are used to measure the
near point of convergence and near point of accommodation.
These points give a guide as to how difficult it is for a
person to view near objects. Many people with eyestrain on
performing near work may be helped by exercises after the
orthoptic evaluation. |
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Corneal Topography |
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The visual disturbance caused by keratoconus is mainly due
to the irregular shape of the corneal surface. In order to
effectively follow the progression of the disease and to fit
a keratoconic cornea with contact lenses it is helpful to
know the precise shape of the cornea. |
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A corneal topographer is a computer linked lighted bowl
with a pattern of concentric rings inside it. The patient is
seated at the bowl with forehead braced against a bar. The
technician has to line up the patient properly and snap
an image. The procedure is painless and very fast. The
computer then uses the snapped image to produce a printout
of the corneal shape using colors to identify different
steep nesses, much like a topographic map of the earth
describes changes in the land surface. Below are some maps
of keratoconic patients. The red and orange colors show
areas of great steepness, and this is where the cone is
located. The doctor can use these maps to follow a cone's
size, shape, and steepness. The numerical data generated by
the computer can also help in contact lens fitting. |
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Specular Microscopy |
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This test is used to
monitor the number, density, and quality of endothelial
cells that line the back of the cornea. A microscope
magnifies the cells thousands of times and the image is
captured with a camera or video camera. The number of cells
within one square millimeter are counted and recorded. The
endothelium of a young, ten-year-old, healthy cornea has
approximately 3,500 cells in each square millimeter. Normal
aging causes the cells to gradually decrease over time. By
age 60, most people have approximately 2,500 cells per
square millimeter. |
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