Search results
Results From The WOW.Com Content Network
The numerical display represents raw values of patient's retinal sensitivity at specific retinal points in dB. Higher numbers equate to higher retinal sensitivities. Sensitivity is greatest in the central field and decreases towards the periphery. Normal values are approximately 30 dB while recorded values of <0 dB equate to no sensitivity ...
This measurement is typically obtained by an orthoptist, ophthalmologist or optometrist during an eye examination using a phoropter. After the patient's distance correction is established, the patient is instructed to view small letters on a card 40 cm from the eyes .
A distant object is defined as an object located beyond 6 meters (20 feet) from the eye. [citation needed] When an object is located close to the eye, the rays of light from this object no longer approach the eye parallel to each other. Consequently, the eye must increase its refractive power to bring those rays of light together on the retina.
Near point of convergence or no previous correction NRC Normal retinal correspondence NV Near vision NWT Normal wearing time o symptoms Zero symptoms Φ Horizontal orthophoria θ Vertical orthophoria ⊕ Horizontal and vertical orthophoria OC's Optical centres Occ. Occupation OD oculus dexter (right eye) OH Ocular history OMB Oculo motor balance
The Marcus Gunn pupil is a relative afferent pupillary defect indicating a decreased pupillary response to light in the affected eye. [3] In the swinging flashlight test, a light is alternately shone into the left and right eyes. A normal response would be equal constriction of both pupils, regardless of which eye the light is directed at.
The eye's Abbe number is independent of the importance of the corrective lens's Abbe, since the human eye: Moves to keep the visual axis close to its achromatic axis, which is completely free of dispersion (i.e., to see the dispersion one would have to concentrate on points in the periphery of vision, where visual clarity is quite poor)
An occluder is placed over the eye that is not being tested (e.g.: over the left eye, to test the right eye's vision). A pinhole occluder is then placed before the patient's eye, and their vision is then tested again (each eye separately) to determine if the patient's poor visual acuity is a result of optical irregularities, or pathological issues.
For light to converge to a perfect point, the wavefront emerging from the optical system must be a perfect sphere centered on the image point. The distance in micrometers between the actual wavefront and the ideal wavefront is the wavefront aberration, which is the standard method of showing the aberrations of the eye.