|   | 
        Group 1 | 
        Group  2 | 
        Group 3 | 
       
      
        | Patients (n) | 
        29 | 
        22 | 
        31 | 
       
      
        | Eyes (n)  | 
        58 | 
        44 | 
        62 | 
       
      
        Sex (n) 
                   Male 
                   Female  | 
         
            18 
          11 | 
         
            17 
          5 | 
         
            9 
          22 | 
       
      
        Age (yr) 
                   Median 
                   Range | 
         
            47  
          11-72 | 
         
            48  
          17-65 | 
         
            39  
          24-59 | 
       
      
        | Eyes with    visual acuity < 6/60 (%) | 
        2/58 (3.4) | 
        2/44 (4.5) | 
        0 | 
       
      
        | Eyes    with color vision defect (%)  | 
        3/58 (5.1) | 
        1/44 (2.2) | 
        0 | 
       
      
        | Eyes    with visual field defect (%)  | 
        2/58 (3.4) | 
        0/22 (0) | 
        0 | 
       
      
        Contrast    Sensitivity 
           (log unit)  
                   Mean  
                   Range | 
         
            1.60 
          (1.35-1.95) | 
         
            1.57 
          (1.50-1.95) | 
         
            1.79 
          (1.65-1.95) | 
       
      |