Richmond Products Inc.
Acuity charts with Landolt C broken ring optotype symbols are acknowledged as one of the most reliable methods for pediatric acuity measurement. A key advantage is that Landolt C broken ring symbols are effective with almost any patient: all age groups from 3 years to adult, illiterate, and not language dependent.
Richmond Products now offers a new series of three card-sized acuity charts, each with Landolt C optotype symbols on one side. Other optototypes on the reverse provide more interesting figures to hold the patient's interest longer.
All three cards have proportional spacing and line sizes of 20/400, 20/320, 20/250, 20/200, 20/160, 20/125, 20/100, 20/80, 20/63, 20/50, 20/40, 20/32, 20/25, 20/20, 20/16, 12/12.5 and 20/10 (6/120 to 6/3 equivalent). Each card measures 3.75 x 6.25 inches (95.25 x 158.75 mm).
Selection of the three optotypes is based on the patient's age and written language ability as follows:
| Optotype |
Patient's AgeRange |
Patient's Language Alphabet or Numbers |
| Landolt C |
All ages |
Any Language |
| Lea™ Symbols |
3 to 5 years |
Any Language |
| Lea™ Numbers |
5 to 8 years |
Arabic numbers |
| Sloan Letters |
9 to adult |
Any Romance Language* |
*Romance Languages are the Indo-European languages based on Latin (mainly Spanish/Castilian, Portuguese French, Italian, Romanian, Catalan, Corsican, Emiliano-Romagnolo, Lombard, Occitan, Gascon, Piedmontese, Aromanian, Sardinian, Sicilian, Venetian, Galician, Asturian, Neapolitan and Friulian).