However, pathologies such as ERM which cause eccentric fixation
may result in the measurement of axial length on a different axis and lead to refractive deviations.
Bilateral eccentric fixation
with no ocular deviation in a case of heredo-macular degeneration.
With the capability to correct for unstable or eccentric fixation
, a measure of sensitivity at any predetermined retinal location can be obtained.
A study by Zeevi, Peli, and Stark (1979) suggested that eccentric fixation
within the near periphery, plus or minus 8 degrees, can be achieved within a short period of time (10-40 seconds), even in individuals who are new to the task.
Final visual acuity was 8/10 with eccentric fixation
Many people with macular disease naturally adopt eccentric fixation
to a degree for distance objects but may not do so consistently or consciously for a wide range of tasks.
Reading with eccentric fixation
is faster in inferior visual field than in left visual field.
Does the patient consistently fixate centrally or shift to eccentric fixation
when viewing larger images?
2) Patients need to be highly motivated with a clearly defined PRL for eccentric fixation
Of these 188, 149 (79%) had a PRL on SLO testing (called PRL), and 125 (66%) had evidence of an eccentric fixation
locus on face field testing, called ffPL (face field preferred locus); that is, they reported a localized area of blurting or loss of detail with respect to their fixation on the nose.
Indeed, some cases do not have any movement on cover testing: the angle of deviation is the same as the angle of eccentric fixation
We hypothesize that the patient shifted to eccentric fixation
when the letter size got too large to be accommodated in the small central spared region.