- 225 Downloads
By definition, the emmetropic eye sees far objects clearly, without needing to accommodate. In all other cases, the eye is said to be ametropic. Donders (1864) established this clear distinction, which was imprecise beforehand, between presbyopia and ametropia. In this chapter, we shall study spherical ametropia (negligible astigmatism). We know that myopes have a real remotum (R < 0), and hyperopes or hypermetropes a virtual remotum (R > 0). The origin of the abscissa is either the corneal apex, in which case the quantity R is called refraction, or the center of the entrance pupil and we then have pupillary refraction Rp. Refraction slightly differs from principal refraction R h which takes the object pp of the eye as its origin.
KeywordsCrystalline Lens Ciliary Muscle Entrance Pupil Uncorrected Visual Acuity Corneal Apex
Unable to display preview. Download preview PDF.