374 



ANATOMY IN A NUTSHELL. 



6. Retinal or oculae hyperesthesia is a condition in which the eye is 

 abnormally sensitive to light. 



7. Ny< i ai.< h'Ia is a condition where the patient can see better in dim light. 



8. Hemianopsia is half blindness, a condition in which there is blindness 

 of one-half of the visual held. 



9. Myopia is short-sightedness, too great refracting power of the eyes so 

 lhat the rays coining from an object beyond a certain distance are fixed in front 

 of the retina. 



PLATE CXCIV. 



MARGINAL ZONE OR LISSAUER S TRACT. 



A Transverse Section of the Cord, Showing Tracts, Diseases, Etc. 



10. Hypermetropia or hyperopia is far-sightedness, the focusing of 

 parellel rays behind the retina. 



11. Presbyopia is long-sightedness, an impairment of vision due to old 

 age dependenl upon diminution of the power of accommodation from loss of 

 elasticity of the crystalline lens, causing the near-point of distinct vision to be 

 removed farther from the eye. 



12. Emmetropia is a normal condition of the eye as respects refraction. 



13. Astigmatism is a condition caused by inequality of the curvature of 

 the different meridians of the cornea. Itmaybe caused by(l) imperfections of 

 the lens, (2) unequal contraction of the ciliary muscles, (3) retinal imperfections. 



