Abstract
Purpose: :
The aim of this study is to investigate the relationship among fixation stability(FS), visual acuity(VA), reading acuity(RA), contrast sensitivity (CS) and multifocal electroretinogram (mfERG) in the patients with macular dystrophies as cone dystrophy (CD) and occult macular dystrophy (OMD).
Methods: :
In sixteen eyes in eight patients with CD and ten eyes with five patients with OMD, fixation points and pattern and retinal sensitivity in the macular area was performed using MP-1(Nidek). We measured best-corrected VA, mfERG was recorded using VERIS (EDI) and the critical print size (CPS) was determined with the Japanese version of Minnesota reading chart (MNREAD-J). CS was tested by using CA2000 (Neitz).
Results: :
Mean log MAR VA was 0.51 in CD eyes and 0.30 in OMD eyes. Mean CPS was 0.61 and 0.43 respectively and mean retinal sensitivity decreased at the retinal lesions in CDs and in the central 2 degree area in OMDs. FS was CD: 52.2±32.7%,OMD: 72.7±20.1% and in the CD eyes with VA < 0.6 logMAR, the FS was below 30%. In OMD patients, FS was below 50% even in the eyes with VA>0.4logMAR. No statistical significance was observed between VA and FS in both CD and OMD eyes. MfERG implicit times of responses from central 5 degrees area, were delayed 1.4msec in CD and 1.2msec in OMD comparing to peripheral area. In CD eyes, the correlations between VA and CPS, CPS and mfERG and CPS and FS showed statistically significant (p<0.01), in OMD eyes the statistical significance can be observed only between CPS and mfERG.
Conclusions: :
FS as assessed with MP-1 is associated with CPS than VA in CDs but in OMDs, FS showed no consistent relationship to VA. Visual acuity testing alone in patients with CD and OMD may not reflect the actual visual function of the patients and their abilities to cope with daily visual tasks. Eyes with macular dystrophies, we should employ not only VA but also as other visual function tests as CS, RA, mf ERG and micro perimeter.
Keywords: electrophysiology: clinical • retina • perimetry