Abstract
Purpose: :
To evaluate the functional sensitivity loss and its relation to topographic location by subjective and objective perimetry in central areolar choroidal dystrophy (CACD).
Methods: :
Seven eyes of four patients (2 female, 2 male) with CACD, ranging between 50 and 61 years of age, were enrolled in the study group. One eye with very low vision (hand movements) was excluded. Fifteen age-matched healthy subjects (8 female, 7 male) were included as control group. MfERG was recorded by Roland-Consult RetiSCAN®, System (Wiesbaden, Germany) in accordance with ISCEV recommendations. The stimulus matrix consisted of 61 scaled hexagonal elements. Amplitude and implicit time of the first positive peak (P1) of the first-order kernel were analyzed. MfERG signals were evaluated using the averaged concentric ring analysis in the groups. Visual fields were tested by Humphrey Field Analyzer (Carl Zeiss Meditec Inc., California, USA) using the 30-2 test point pattern with SITA-FAST strategy. HVF testing results was also evaluated in 5 concentric rings with averaged concentric retinal sensitivity corresponding to mfERG rings, in order to compare the results to concentric ring analysis in mfERG. The differences of test results between the control and the study group were evaluated by Mann-Whitney U test, and the correlations by Spearman test.
Results: :
Snellen VA of the eyes with CACD ranged from 0.1 to 0.7 (0.46±0.20, mean logMAR VA:0.40±0.29). HVF revealed central scotoma in 6 of 7 eyes (85.7%), whereas a paracentral scotoma extending to fixation point was detected in 1 eye. Mean retinal sensitivity in each concentric ring in HVF was significantly lower (p<0.001) in ring 1 (R1) to R4, and in R5 (p=0.017) in CACD patients. Similarly, CACD patients had lower P1 and N1 amplitudes (p<0.01) in R1 to R5, and delayed P1 (p<0.01) and N1 implicit times (p<0.05) in R3 to R5. P1 and N1 amplitudes in mfERG positively correlated to the retinal sensitivity in the corresponding HVF-R1 to R5 (p<0.01). P1 and N1 implicit times were negatively, but insignificantly correlated to HVF-R1 retinal sensitivity.
Conclusions: :
The mfERG findings well correlate to automated perimetric thresholds in CACD. Both tests reveal retinal pathology beyond ophthalmoscopically discernable retinal areas. This study implies existence of incipient or ongoing retinal degeneration in CACD.
Keywords: choroid • degenerations/dystrophies • electrophysiology: clinical