Eagleview Eye Clinic

Tag eye care professionals

FOVEA CENTRALIS

The fovea centralis is a small pit in the macula of the retina, responsible for sharp central vision.

Key functions:

  1. High-acuity vision
  2. Color vision
  3. Central vision

Importance:

The fovea is crucial for tasks like reading, driving, and recognizing faces.

VISUAL AXIS

The visual axis is an imaginary line connecting the fixation point to the fovea centralis, passing through the nodal points of the eye.

Key points:

  1. Line of sight: Connects fixation point to fovea
  2. Important for: Understanding visual perception and eye alignment
  3. Used in: Ophthalmology, optometry, and vision science
SEGMENT HEIGHT

Segment height refers to the vertical measurement of a bifocal or progressive lens segment.

What it’s for:

Segment height is used to:

  1. Position the lens segment correctly
  2. Ensure optimal vision through the segment

Measurement:

Segment height is typically measured from the lower eyelid margin to the top of the segment.

Krimsky test

The Krimsky test is used to measure strabismus (misaligned eyes) in patients who can’t fixate or have poor fixation.

What it’s for:

The Krimsky test is used to:

  1. Measure strabismus in patients with poor fixation
  2. Assess ocular alignment

How it’s done:

  1. A light is shone into the patient’s eyes.
  2. Prisms are placed in front of the deviated eye.
  3. The prism is adjusted until the corneal reflections are symmetrical.

What it shows:

The test measures the amount of strabismus, helping diagnose and manage eye alignment issues.

VON GRAEFE TEST

The Von Graefe test, also known as the Von Graefe’s prism test, is used to measure the amount of heterophoria (latent strabismus).

What it’s for:

The Von Graefe test is used to:

  1. Measure heterophoria (latent strabismus)
  2. Assess binocular vision

How it’s done:

  1. The patient is asked to look at a target.
  2. A prism is placed in front of one eye.
  3. The prism is adjusted until the patient reports alignment of the target.
  4. The amount of prism required to align the target measures the heterophoria.

VAN HERRICK TEST

The Van Herrick test is a method used to estimate the depth of the anterior chamber angle in the eye.

What it’s for:

The Van Herrick test is used to:

  1. Assess the risk of angle-closure glaucoma
  2. Evaluate the anterior chamber angle width

How it’s done:

  1. A narrow slit beam is shone onto the peripheral cornea.
  2. The examiner observes the angle between the cornea and iris.
  3. The width of the angle is estimated and graded.

Grading:

The Van Herrick test grades the angle as:

  1. Grade 4: Wide open angle
  2. Grade 3: Moderate angle
  3. Grade 2: Narrow angle
  4. Grade 1: Extremely narrow angle
  5. Grade 0: Closed angle

What it shows:

The test helps identify patients at risk of angle-closure glaucoma, allowing for further evaluation and treatment if necessary.

VERTICAL COINCIDENCE

The vertical coincidence test is a method used in ophthalmology and optometry to assess the alignment of the eyes.

What it’s for:

The vertical coincidence test is used to:

  1. Detect and measure vertical deviations (misalignments) of the eyes
  2. Assess binocular vision and eye alignment
  3. Diagnose and manage conditions like hypertropia (one eye higher than the other) and other vertical strabismus disorders

How it’s performed:

  1. The patient is asked to look at a target, usually a light or an object.
  2. A prism is placed in front of one eye to measure the deviation.
  3. The prism is adjusted until the two images seen by the patient appear to be vertically coincident (aligned).
  4. The amount of prism required to achieve alignment is a measure of the vertical deviation.

What it shows:

The test shows the amount of vertical misalignment between the two eyes, helping diagnose conditions like:

  1. Hypertropia (one eye higher than the other)
  2. Hypotropia (one eye lower than the other)
  3. Other vertical strabismus disorders

The vertical coincidence test provides valuable information about eye alignment and helps diagnose and manage vertical strabismus. If you have more questions or need further clarification, feel free to ask.

HORIZONTAL COINCIDENCE TEST

The horizontal coincidence test, also known as the cover-uncover test or Hirschberg’s test, assesses binocular alignment and detects strabismus (misaligned eyes).

How it’s done:

  1. Patient fixates: The patient looks at a target, usually a light or object.
  2. Covering one eye: One eye is covered, and the movement of the uncovered eye is observed.
  3. Uncovering the eye: The covered eye is uncovered, and the movement of both eyes is observed.

Purpose:

The test helps detect:

  1. Strabismus: Misalignment of the eyes (esotropia, exotropia, hypertropia, etc.).
  2. Binocular vision problems: Issues with how the eyes work together.

The test provides valuable information about binocular alignment and helps diagnose and manage strabismus and other binocular vision problems.

THE BJERRUM TANGENT SCREEN

The Bjerrum tangent screen is a device used in ophthalmology to assess the visual field, particularly the central and paracentral areas. It’s a flat surface with a tangent curve marked on it, used to map out the field of vision.

How it’s used:

  1. Patient fixation: The patient fixates on a central point.
  2. Stimulus presentation: A stimulus (e.g., a small object or light) is moved along the tangent screen.
  3. Visual field mapping: The patient indicates when they see the stimulus, allowing the examiner to map out the visual field.

Purpose:

The Bjerrum tangent screen is used to:

  1. Detect visual field defects: Identify defects in the central and paracentral visual field.
  2. Monitor glaucoma: Track changes in the visual field associated with glaucoma.
  3. Assess optic nerve function: Evaluate the function of the optic nerve.

The Bjerrum tangent screen is a useful tool for assessing and monitoring visual field defects, particularly in glaucoma patients.

FARNSWORTH D15 TEST

The Farnsworth D15 test is a color vision test used to assess color perception and detect color vision deficiencies. Here’s a detailed overview:

Test Procedure:

  1. Colored caps: The test consists of 15 colored caps, each with a specific hue.
  2. Arranging the caps: The patient is asked to arrange the caps in a specific order, typically in a hue sequence.
  3. Testing conditions: The test is usually administered in a well-lit room with good color rendering.

Purpose:

The Farnsworth D15 test is used to:

  1. Detect color vision deficiencies: Identify individuals with color vision problems, particularly in the blue-yellow axis.
  2. Assess color discrimination: Evaluate the patient’s ability to distinguish between different colors.
  3. Monitor color vision: Track changes in color vision over time or after treatment.

Scoring and Interpretation:

  1. Error score: The number and type of errors are recorded and scored.
  2. Color confusion index: The results are often presented as a color confusion index, which indicates the severity of color vision deficiency.
  3. Interpretation: The results help diagnose and classify color vision deficiencies, such as tritanopia (blue-yellow deficiency).

Applications:

  1. Occupational vision assessments: Used in industries where color vision is critical, such as aviation, transportation, or graphic design.
  2. Clinical assessments: Helps diagnose and manage color vision problems in patients.
  3. Research: Used in studies on color vision and its applications.

The Farnsworth D15 test is a valuable tool for assessing color vision and detecting color vision deficiencies, enabling targeted interventions and accommodations.