26 - Risk factors for cataract

1. Increasing age - oxidative damage to membranes and proteins


2. sunlight ( especially the UV-A, UV-B components ) - hydration


3. severe diarrhoeal dehydration - denaturation of proteins


4. vitamins A, C, E deficiency - opacification of lens fibres with fibrous metaplasia


5. diabetes - opacification of lens epithelium


6. smoking - accumulation of pigmented molecules
                    ( 3-hydroxykynurenine and chromophores which lead to yellowing )


7. corticosteroids - disturbance in osmotic balance


8. genetic - failure of ion pumps ( increased intralenticular calcium and sodium with decrease in potassium )

25 - Sherrington law of reciprocal innervation

During the initiation of an eye movement, increased innervation to an extraocular muscle is accompanied by simultaneous inhibition ( a reciprocal decrease in innervation ) of the direct antagonist of the contracting muscle of the same eye.

                             

If the left medial rectus muscle receives innervational flow to initiate adduction of the left eye, there is simultaneous decreased and inhibitory flow to the left lateral rectus muscle to make it relax and enable the eyeball to move medially.