Progression of Visual Acuity and Fundus Autofluorescence in Recent-Onset Stargardt Disease: ProgStar Study Report #4.

PURPOSE

To investigate the impact of areas of decreased fundus autofluorescence (AF) on visual acuity (VA) in molecularly confirmed Stargardt disease (STGD1) with recent symptom onset, and investigate the association between these structural and functional measures over time.

DESIGN

Prospective, international, multicenter observational study of Stargardt disease.

PARTICIPANTS

Sixty-four patients (124 eyes) aged ≥6 years at first study visit, with onset of symptoms ≤2 years before the first visit.

METHODS

AF images were graded for the presence and areas of definitely decreased AF (DDAF), questionably decreased AF (QDAF), and total decreased AF (DAF). First-visit images were also graded for presence of these lesions and for the presence of increased AF in the fovea. VA was measured as best-corrected or presenting acuity and converted to logarithm of the minimum angle of resolution (logMAR). Cross-sectional associations were measured using linear models with generalized estimating equations. Longitudinal linear mixed effects models were used to estimate yearly progression rates of VA and AF lesion areas. Main outcome measures were rate of change in VA and rate of change of decreased AF area.

RESULTS

In cross-sectional analyses at baseline, VA was not significantly associated with area of DDAF (P = 0.86), or QDAF (P = 0.11), but was significantly associated with lesion involvement in the fovea (P < 0.001). The VA change rate was 0.054 logMAR/year (P < 0.001) and depended on initial level of VA (faster loss was observed in those with 20/30 to 20/70 at first visit, 0.114 logMAR/year, 95% confidence interval = 0.090-0.138). Growth of DDAF depended on the size of the lesion at first visit, with larger DDAF having faster growth. Regression of QDAF area over time was associated with significantly larger growth in DDAF (P < 0.001), suggesting that QDAF areas may lose further AF signal over time. The increase in area of DDAF, or total decreased AF, was not associated with change in VA (P = 0.62, and P = 0.27, respectively).

CONCLUSIONS

In recent-onset STGD1, the rate of VA loss was not significantly associated with the rate of increase in area of DDAF, QDAF, or DAF. For DDAF, the growth rate depended on the initial size of the lesion, a finding that will be helpful in stratifying these patients for intervention.