Fixation Location and Stability in Best Vitelliform Macular Dystrophy

Purpose: To analyze fixation location and stability in best vitelliform macular dystrophy (BVMD) and test their association with best-corrected visual acuity (BCVA).Design: Observational, cross-sectional study.Participants: Thirty patients (55 eyes) affected by genetically confirmed BVMD were followed up at the Retinal Heredodystrophies Unit of IRCCS San Raffaele Scientific Institute, Milan.Methods: Patients underwent testing with macular integrity assessment (MAIA) microperimeter. Fixation location was measured as distance in degrees (& DEG;) between preferred retinal locus (PRL) and estimated fovea location (EFL); fixation was defined as eccentric when the distance between PRL and EFL exceeded 2 & DEG;. Fixation stability was graded as stable, relatively unstable, or unstable and expressed as bivariate contour ellipse area (BCEA, & DEG;2).Main Outcome Measures: Fixation location and stability.Results: The median distance of the PRL from the anatomic fovea was 0.7 & DEG;, and fixation location was eccentric in 27% of eyes. Fixation was graded as stable in 64% of eyes, relatively unstable in 13%, and unstable in 24%, with a median 95% BCEA of 6.2 & DEG;2. The atrophic/fibrotic stage was associated with worse fixation pa-rameters (all P < 0.01). Both PRL eccentricity and fixation stability were linearly associated with BCVA: every 1 & DEG; increase in PRL eccentricity was associated with a 0.07 logarithm of the minimum angle of resolution (logMAR) worse BCVA (P < 0.0001) while every 1 & DEG;2 increase in 95% BCEA was associated with a 0.01 logMAR worse BCVA (P < 0.001). No significant intereye correlation was found for PRL eccentricity and fixation stability, as well as no association between the patient's age and fixation parameters.Conclusions: We demonstrated that most eyes affected by BVMD retain a central stable fixation and pro-vided evidence that both fixation eccentricity and stability are strongly associated with visual acuity in BVMD. These parameters may serve as secondary end points for future clinical trials.Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology Science 2023;3:100329 & COPY; 2023 by the American Academy of Ophthalmology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).