Figure 3. Visual field test results obtained on the right (RE) and the left eye (LE) of the two patients BT188 and BT189. A: Result of measuring the visual fields on BT189 at 28 years of age. B: Result of measuring the visual fields on BT188 at the age of 18 years. A series of random lights of different intensities are flashed in the peripheral field of vision of both patients. When they perceive the computer-generated light suddenly appearing in their field of view they press a button to indicate their responses, then we see this spot (Dot see). If the patient is unable to see the light in an appropriate portion of his field of view, then we see on the computer a spot (Dot don’t see) indicating vision loss. Visual field loss was more severe in the older brother BT189. But in both patients, the nasal and temporal fields were not preserved, and only the central field was maintained.