Question
Identify the instrument in the given image?
| A. |
Phoropter |
| B. |
Maddox rod |
| C. |
Gonioscope |
| D. |
Maddox wing |
Show Answer
|
Correct Answer � B Explanation |
 |
- The given instrument in the image is a Maddox rod.
- The Maddox rod test uses a specially constructed device consisting of a series of parallel cylinders that converts a point source of light into a line image.
- The optical properties of the cylinders cause the streak of light to be situated 90° to the orientation of the parallel cylinders.
- Because fusion is precluded by the Maddox rod, heterophorias and heterotropias cannot be differentiated.
- The Maddox rod can be used to test for horizontal and vertical deviations, and, when used in conjunction with another Maddox rod, for cyclodeviations.
Interpretation:
To test for horizontal deviations:
- The Maddox rod is placed in front of one eye (for this example, the right eye) with the cylinders in the horizontal direction.
- The patient fixates a point source of light and then sees a vertical line with the right eye and a white light with the left eye. If the light superimposes the line, orthophoria is present.
- In this example, if the light is on the left side of the line, an esodeviation is present; and if the light is on the right side of the line, an exodeviation is present.
- A similar procedure with the cylinders aligned vertically is used to test for vertical deviations.
- Orthophoria: Perfect ocular alignment in the absence of any stimulus for fusion.
- Hypophoria: Latent imbalance
- Exophoria: Outward imbalance
- Esophoria: Small inward imbalance.
