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Diagnostic Tests

The NorthShore Eye and Vision Center uses the most up-to-date diagnostic tests and ophthalmologic equipment to assist our trained ophthalmologists in diagnosing acute and chronic eye conditions. Through the use of imaging, sight tests and more, our physicians work to pre-emptively diagnose potential causes for vision errors, injuries and irritations, as well as get an in-depth look at the eye, allowing for more personalized treatment strategies for each patient dependent on our observations. This can be especially critical in preventing and slowing down advanced diseases. Our diagnostic tests include:

Standard Eye Exams | Corneal Exams | Retinal Exams | Imaging

Standard Eye Exams

  • Visual Acuity Test – Measures how well patients see from a distance by reading letters and numbers of different sizes on an eye chart. This helps detect changes in vision.
  • Refraction Test – Uses a device (phoroptor or refractor) to determine the amount of refractive error in a patient’s vision. This helps ophthalmologists to determine vision errors, vision loss or damage, as well as assess the right lenses for glasses or contact prescriptions.
  • Visual Field (Perimetry) Test – Detects any gaps in peripheral (side) vision using a perimeter, a rounded instrument in which patients will keep a fixed gaze while a series of lights flash. Patients press a button each time they see a light, which is recorded by a computer. This is used to detect damage caused by chronic conditions like glaucoma, or retinal damage.
  • Color Vision Test – Patients are asked to identify a series of numbers within colored dot patterns. The results determine errors in color vision.
  • Slit Lamp Exam – Patients will sit in a chair attached to a large microscope, while their ophthalmologist shines a light through the other side to examine a magnified view of the eye, including the cornea, lens and iris. This test can be used to identify damage, inflammation, blockage and vision loss.
  • Dilated Eye Exam – Ophthalmologist uses eye drops to widen the pupils and examine the back of the eye (retina) using a bright light. They will be able to see developing diseases like cataracts, diabetic retinopathy and macular degeneration through symptoms such as damaged optic nerves or retinas.
  • Amsler Grid Test – Patients focus on a black dot on a grid of lines – any distortion in the lines indicates vision problems, such as macular degeneration.
  • Gonioscopy – Patients are positioned to look through a slit lamp with a special lens, and an ophthalmologist will shine a beam of light into the eye in order to see the drainage angle between the cornea and the iris. This is important in diagnosing the specific form of glaucoma a patient is suffering from.

Corneal Exams

  • Intraocular Pressure (Tonometry) – Measures the pressure inside the eye using a pen-like tool to press against the cornea (numbed) while a doctor looks through a slit lamp. This test is useful in diagnosing glaucoma through changes in the optic nerve.
  • Corneal Topography (Orbscan) – Maps the shape and curvature of the cornea. Patients are seated, looking a bowl-shaped instrument with a series of rings in it while flash photography is taken. This test can determine changes in vision due to an abnormal cornea, as associated with keratoconus, astigmatism or corneal thinning.
  • Corneal Pachymetry – Using a pachymeter, an ultrasound probe, an ophthalmologist can measure corneal thickness by placing it against the cornea after numbing. This can be used to discover corneal abnormalities such as thinning or swelling, and confirm intraocular pressure, which is useful in diagnosing glaucoma and determining a patient’s eligibility for refractive surgeries such as LASIK.
  • Keratometry – Measures the curvature and strength of the cornea. Patients will sit in front of a keratometer, showing the ophthalmologist a magnified image of the cornea. Results can determine the severity of astigmatism and cataracts.

Retinal Exams

  • Ophthalmoscopy/Fundoscopy – An ophthalmoscope shines a beam of light into the pupil, allowing an ophthalmologist to see the back of the eye (fundus) in order to examine the retina and optic nerve for diagnosing damage relating to glaucoma and other vision problems.
  • Fluorescein Angiography – Fluorescent dye is injected through a vein in the arm into the bloodstream and the patient is positioned in front of a camera which will take pictures showing the blood vessels within the retina. Ophthalmologists may use this to diagnose abnormalities such as diabetic retinopathy, macular degeneration, high blood pressure, circulatory issues, growths and swelling.


  • A-scan Biometry – A small device is placed against the eye while ultrasound images are taken. The images will display the length and thickness of tissue in the eye, which is helpful in diagnosing cataracts and patient eligibility for surgery, as well as identifying any growths within the lens.
  • B- Scan – A probe is held against a patient’s eye to take ultrasound imagery that shows the structures within the eye more clearly than a standard eye exam. This can be useful in diagnosing damage such as retinal detachment, growths, damage and causes of vision loss.
  • LipiScan - The diagnosis of meibomian gland dysfunction MGD can be aided with LipiScan. LipiScan allows us to directly view the health of your meibomian glands in high definition. LipiScan has revolutionized the diagnosis of dry eye caused by meibomian gland dysfunction MGD.