The buffer reactions are:

  
    
      
        
          
            H
            
              +
            
          
          +
          
            HCO
            
              3
            
            
              −
            
          
          
            
              
                
                  
                    
                      ↽
                    
                    
                    
                    
                      −
                    
                  
                
              
              
                
                  
                    
                      −
                    
                    
                    
                    
                      ⇀
                    
                  
                
              
            
          
          
            H
            
              2
            
            
              
            
          
          
            CO
            
              3
            
            
              
            
          
          
            
              
                
                  
                    
                      ↽
                    
                    
                    
                    
                      −
                    
                  
                
              
              
                
                  
                    
                      −
                    
                    
                    
                    
                      ⇀
                    
                  
                
              
            
          
          
            CO
            
              2
            
            
              
            
          
          +
          
            H
            
              2
            
            
              
            
          
          O
        
      
    
    {\displaystyle {\ce {H+ + HCO3- <=> H2CO3 <=> CO2 + H2O}}}
  The Henderson-Hasselbalch equation mathematically describes the relationship between blood pH and the components of the bicarbonate buffering system:

  
    
      
        
          pH
        
        =
        
          
            pK
          
          
            a
          
        
        +
        
          
            L
            o
            g
          
        
        ⁡
        
          
            
              [
              
                
                  HCO
                
                
                  3
                
                
                  −
                
              
              ]
            
            
              [
              
                
                  CO
                
                
                  2
                
              
              ]
            
          
        
      
    
    {\displaystyle {\text{pH}}={\text{pK}}_{a}+\mathop {\mathrm {Log} } {\frac {\left[{\text{HCO}}_{3}^{-}\right]}{\left[{\text{CO}}_{2}\right]}}}
  

Using Henrys law, we can say that [CO2] = 0.03 × PaCO2
(PaCO2 is the pressure of CO2 in arterial blood)
Adding the other normal values, we get
  
    
      
        
          pH
        
        =
        6.1
        +
        
          
            L
            o
            g
          
        
        ⁡
        
          [
          
            
              24
              
                0.03
                ×
                40
              
            
          
          ]
        
      
    
    {\displaystyle {\text{pH}}=6.1+\mathop {\mathrm {Log} } \left[{\frac {24}{0.03\times 40}}\right]}
  

  
    
      
        =
        6.1
        +
        1.3
      
    
    {\displaystyle =6.1+1.3}
  

  
    
      
        =
        7.4
      
    
    {\displaystyle =7.4}

Consequences
Acute Metabolic Acidosis
Acute Metabolic Acidosis most often occurs during hospitalizations, and acute critical illnesses.
There is no widely accepted treatment for ODD, although some clinicians will prescribe eye drops designed to decrease the intra-ocular pressure and theoretically relieve mechanical stress on fibers of the optic disc. Rarely choroidal neovascular membranes may develop adjacent to the optic disc threatening bleeding and retinal scarring. Laser treatment or photodynamic therapy or other evolving therapies may prevent this complication. Prognosis
Optic nerve damage is progressive and insidious. Some of patients will develop some peripheral field defects. These can include nasal step defects, enlarged blind spots, arcuate scotomas, sectoral field loss and altitudinal defects. Clinical symptoms correlate to visibility of the drusen. Central vision loss is a rare complication of bleeding  from peripapillar choroidal neovascular membranes. Anterior ischemic optic neuropathy (AION) is a potential complication. Epidemiology
Optic disc drusen are found clinically in about 1% of the population but this increases to 3.4% in individuals with a family history of ODD. About two thirds to three quarters of clinical cases are bilateral. A necropsy study of 737 cases showed a 2.4% incidence with 2 out of 15 (13%) bilateral, perhaps indicating the insidious nature of many cases. An autosomal dominant inheritance pattern with incomplete penetrance and associated inherited dysplasia of the optic disc and its blood supply is suspected. Males and females are affected at equal rates. Caucasians are the most susceptible ethnic group. Certain conditions have been associated with disc drusen such as retinitis pigmentosa, angioid streaks, Usher syndrome, Noonan syndrome and Alagille syndrome.