Fixation Stability and Preferred Retinal Locus in Advanced Age-Related Macular Degeneration

Abstract

Objectives: To evaluate fixation stability and characteristics of the preferred retinal locus (PRL) in patients with advanced age-related macular degeneration (AMD). Materials and Methods: Sixty-three eyes of 63 patients with AMD who presented to the low vision unit were included in this prospective study. Sociodemographic characteristics, eye examination findings, and reading performance results with the Minnesota Low Vision Reading test were evaluated. Microperimetry was used to evaluate fixation stability and PRL characteristics. Results: There was unstable fixation in 68% of the eyes, relative stable fixation in 27%, and stable fixation in 5%. The mean PRL-foveal distance was 5.15°±3.31° (range 0.75°-14.2°). PRL-foveal distance was greater in cases with unstable fixation than cases with stable fixation (p=0.023). Distance of the PRL from the lesion margin was not associated with absolute scotoma size or fixation stability (p=0.315, p=0.095, respectively). PRLs were most frequently located in the nasal quadrant (31%), followed by the superior quadrant (26%) of the retina. There was no significant relationship between PRL location and fixation stability (p=0.088). Fixation stability was significantly associated with reading speed (p=0.003). Conclusion: In advanced AMD, PRL-foveal distance is an important factor in fixation stability. Knowing the factors that affect fixation stability may be important in determining low vision rehabilitation strategies for these patients because of the strong association between fixation stability and reading speed.

Visual function and biofeedback training of patients with central vision loss: a review

“…As a tool for assessing the ability to sustain gaze at a fixed target, fixation stability is associated with the duration of the test and the visual function of the patient [37] . Fixation stability has a strong relationship with reading speed [7] and BCVA [40] in patients with CVL, but does not correlate with reading distance [41] . Fixation stability decreases with age in normal healthy people [42] .…”

“…The closer the distance between the fovea and TRL, the greater the maximum reading speed, reading acuity, and critical print size [67] . However, Altınbay and İdil [7] found that the foveal-PRL distance had no influence on fixation stability in patients with AMD. Different TRL training frequencies and locations also influenced the effects of biofeedback training.…”

“…MD not only irreversibly damages the fovea, which has the best visual acuity, but also affects the oculomotor nerve function, which is used by the visual system to plan and execute saccades and microsaccades [6] . As the disease progresses, the central visual acuity of patients with MD gradually decreases and forms a central scotoma, leading to a consistent decrease in fixation stability [7] . Patients present with a gradually progressive visual symptoms such as reading, face recognition, and driving difficulties.…”