A Manual of Ophthalmic Practice |
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Page 5
... axis . — In lenses whose two surfaces are spherical the centres for the surfaces are called centres of curvature and the right line which passes through these two centres is the principal axis . In considering the path of rays through ...
... axis . — In lenses whose two surfaces are spherical the centres for the surfaces are called centres of curvature and the right line which passes through these two centres is the principal axis . In considering the path of rays through ...
Page 6
... L , by comparing the path of the diverging ray LB with that of the ray SB parallel to the axis , the former is found to make with the normal an angle , LBn , greater than the angle SBn ;. 6 MANUAL OF OPHTHALMIC PRACTICE .
... L , by comparing the path of the diverging ray LB with that of the ray SB parallel to the axis , the former is found to make with the normal an angle , LBn , greater than the angle SBn ;. 6 MANUAL OF OPHTHALMIC PRACTICE .
Page 7
... axis at a point I which is more dis- tant than the principal focus F. As all rays from the point L cut the axis approximately at 7 , this point is what is called the conjugate focus of the point L. The term con- jugate focus expresses ...
... axis at a point I which is more dis- tant than the principal focus F. As all rays from the point L cut the axis approximately at 7 , this point is what is called the conjugate focus of the point L. The term con- jugate focus expresses ...
Page 8
... axis , and this point is the virtual focus of the point L. Foci in double concave lenses . - In double con- cave lenses there are only virtual foci , whatever the dis- tance of the object . In Fig . 8 let SI , S'K be any pencil of rays ...
... axis , and this point is the virtual focus of the point L. Foci in double concave lenses . - In double con- cave lenses there are only virtual foci , whatever the dis- tance of the object . In Fig . 8 let SI , S'K be any pencil of rays ...
Page 9
... axis . - In every lens there is a point called the optical centre , which is situ- ated on the principal axis , and which has the property that K B ' C B A K FIG . 10 . any luminous ray passing through this point experiences no angular ...
... axis . - In every lens there is a point called the optical centre , which is situ- ated on the principal axis , and which has the property that K B ' C B A K FIG . 10 . any luminous ray passing through this point experiences no angular ...
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Common terms and phrases
accommodation affected amblyopia anomaly of refraction anterior chamber appear asthenopia astigmatism atrophy atropine axis bandage become blood cataract cause centre chamber choroid ciliary region colour commenced concave lens congenital conjunctiva convergence convex lens cornea corneal margin corneitis curette curvature degree of myopia dilated dioptric direction disease displacement distance emmetropic examination extraction eyeball eyelids forceps foreign body fundus glasses glaucoma globe hæmorrhage horizontal hypermetropia hypermetropic astigmatism incision increased inflammation inflammatory injury intolerance of light iridectomy iris iritis keratitis knife lachrymal lenses less lids lines lint lotion muscle myopia object occur ocular opacity opaque operation ophthalmia ophthalmoscope optic disc orbit pain paralysis passed patient performed portion posterior presbyopia pupil rays of light removed retina retinal vessels right angles scissors sclerotic seen sight spots staphyloma strabismus suppuration surface sutures sympathetic ophthalmia symptoms synechia syphilitic tension tion treatment tumour ulceration usually vitreous wire speculum wound
Popular passages
Page 318 - Walsham, besides being an excellent surgeon, is a teacher in its best sense, and having had very great experience in the preparation of candidates for examination, and their subsequent professional career, may be relied upon to have carried out his work successfully. Without following out in detail his arrangement, which is excellent, we can at once say that his book is an embodiment of modern ideas neatly strung together, with an amount of careful organisation well suited to the candidate, and,...