A. Morphologic:
1. Capsular Cataract
     a. Anterior Capsular
          -Congenital: from persistent pupillary membrane
          -Acquired: Pseudoexfoliation syndromes, chlorpromazine, in association with posterior
                           synechiae
     b. Posterior capsular: 
          -Congenital: in association with persistent hyaloid remnants (Mittendorf's dot)

2. Subcapsular Cataract
     a. Posterior Subcapsular
          -Complicated (e.g. in Diabetes Mellitis, Myotonic Dystrophy, steroids, irradiation)
          -Age -related
           Fig.1: Posterior Subcapsular Cataract ( click to enlarge)
           Fig. 1: Annotated (click to enlarge)
           Fig. 2: Posterior Subcapsular Cataract (by retro illumination)
     b. Anterior Subcapsular
         -Acute angle closure glaucoma(Glaukomfleckens), amiodarone toxicity, miotics, 
           Wilson's disease
          Fig. 3: Anterior Subcapsular Cataract (click to enlarge)
          Fig. 3 Annotated
3. Nuclear Cataract
         -Age-related
         -Congenital: Rubella, Galactosemia
4. Cortical Cataract
         -Usually spoke-like, can be anterior or posterior
         -Can be congenital (very common)
         -Usually doesn't interfere with vision
5.  Lamellar Cataract
         -Congenital. Involves one lamella of the fetal or nuclear zone
6.  Sutural Cataract
         -Congenital
         -Very common
         -Y-shaped opacity in the lens nucleus
         -No clinical significance

B. Maturity

1. Immature Cataract
    -scattered opacities are separated by clear areas
2. Mature
    -Cortex is totally opaque
     Fig. 4: Mature Cataract (click to enlarge)
     Fig. 5: Cataracta Rubra (click to enlarge)
3. Intumescent
    -The lens has become swollen by imbibed water
    -Can be mature or immature
4. Hypermature Cataract
    -Mature cataract that has become swollen and has a wrinkled capsule as a result of
      leakage of water out of the lens.
5. Morgagnian Cataract:
    -Hypermature cataract leading to total liquefaction of the cortex making the nucleus sink 
      inferiorly

C. Age of onset
1. Congenital
2. Infantile
3. Juvenile
4. Pre-senile
5. Senile

II. Etiology
A. Age-related 
     1. Sub-capsular
         a. Anterior: due to fibrous metaplasia of the anterior lens epithelium
         b. Posterior: just in front of the posterior capsule. It is associated with the posterior
                           migration of the anterior epithelium of the lens
            -Patients with posterior sub-capsular cataract are more troubled than those with the
             anterior ones, particularly from headlights of oncoming cars and bright sunlight.
            -Near vision in these patients is  also poorer than distance vision
      2. Nuclear Cataract
            -Exaggeration of the normal aging involving the lens nucleus (frequently preceded by 
              radial water clefts in the cortex.
            -Often associated with myopia from the increase in the refractive index and increase 
              in the bi-convexity of  lens. Some elderly patients with Nuclear Sclerosis may be able 
              to read again without their spectacles, due to the induced myopia: this explains the "second
              sight of the aged".
B. Trauma can cause cataract: concussion, penetrating, electric shock or lightening.
C.. Metabolic
      1. DM
            -Senile cataract is accelerated
            -True diabetic cataract: associated with over-hydration. Results in bilateral white punctate 
              or snowflake posterior or anterior sub-capsular opacities
      2. Galactosemia, Glalactokinas deficiency, mannosidosis, hypocalcemic syndromes 
          (multifocal white flakes)
      3. Toxic 
           -Steroids: systemic cause more cataract than topical. A dose <10mg/d or given for less than
             one year is generally safe. Individual variability as well as dose and duration are all important.
            Cause anterior and posterior sub-capsular lens opacities.
          -Chlorpromazine: causes anterior lens capsule opacities
          -Amiodarone: causes anterior sub-capsular opacities.
          -Gold (used in Rheumatoid Arthritis): 50% have posterior lens opacities
          -Miotics: cause anterior sub-capsular opacities
      4. Secondary Cataract
           -Chronic anterior uveitis
      5. Miscellaneous
           -Hereditary fundus dystrophy: Retinitis Pigmentosa, Leber's,..
           -High Myopia
           -Acute angle closure glaucoma (Glaukomfleckens): anterior capsular or sub-capsular 
             opacitiesin the pupillary zone
           -Myotonic Dystrophy: Fine polychromatic granules in the cortex( "Blue-dot cataract"),
            followed later by sub-capsular stellate opacities ("Christmas tree")
            Fig. 6: Blue dot cataract (click to enlarge)
           -Atopic Dermatitis: bilateral anterior or posterior stellate opacities
           -Down's syndrome
      6. Intra-uterine
          -Congenital Rubella: 15% of cases. After the 6th week, the virus is no more capable of crossing
            the lens capsule.
          -Toxoplasmosis
          -CMV
          -Maternal ingestion of Thalidomide, steroids,...
      7. Hereditary
          -Usually dominant
          -Congenital to pre-senile