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Grating acuity with varying field size in patients and normal infants
Elisabeth Schulz1, Barbara Jänicke, Judith Wundenberg
1Orthoptic Department, University Eye Clinic, Hamburg, Germany. eschulz@uke.uni-hamburg.de
Purpose:
To investigate the effect of field size on grating acuity assessment in normal children and pediatric ophthalmological patients.
Method:
A prototype set of acuity cards was produced with three acuity steps per octave and a card size of 26 x 70 cm, bearing a grating field of 26 x 35 cm. Field size reduction was achieved by masking. Large fields of the prototype versus TAC-sized fields were tested in normal infants and ophthalmological patients.
Results:
Teller acuity cards (TAC) and masked prototype cards of equal field size gave identical results in normal controls and pediatric ophthalmological patients. A better response to large fields was found in all normal infants up to 7 months of age and in none older than 15 months. In patients, an effect of field size was found in decreasing numbers up to 5 years of age. The interocular acuity difference was larger when small fields were presented.
Conclusion:
The effect of field size in patients is considered to be a developmental delay due to the individual history of disease. It may possibly have prognostic value for treatment.