Search results
Results from the WOW.Com Content Network
by convention, an axis of 90° is vertical, 0° or 180° are horizontal; if the cylinder power is positive, the lens is most convergent 90° from the axis; if the cylinder power is negative, the lens is most divergent 90° from the axis; if the cylinder power is zero, the lens is spherical and has the same power in every meridian
By measuring this zone, the autorefractor can determine when a patient's eye properly focuses an image. The instrument changes its magnification until the image comes into focus. The process is repeated in at least three meridians of the eye and the autorefractor calculates the refraction of the eye, sphere, cylinder and axis.
oculus dexter (right eye) OH Ocular history OMB Oculo motor balance ONH Optic nerve head Oph Ophthalmoscopy OS oculus sinister (left eye) OU oculus uterque (both eyes) PD Pupillary distance PERRLA Pupils equal, round, reactive to light and accommodation PH Pinhole see Pinhole occluder and Visual_acuity#Legal_definitions: PHNI Pinhole No Improvement
The lenses were increased to 3 ⁄ 4 inch diameter, the permanent size, and the unit was much more massive, with a weight of 7 lb. 9 oz., and with a range of +16.87 to -19.12 sphere and 6.00 cylinder, with auxiliary lenses to increase these to +18.87/-21.12 sphere and 8.00 cylinder. All these models resembled the original DeZeng model in design ...
Step 1: Using the +/-0.50DS on the confirmation set to determine the initial best sphere correction. Step 2: Presenting the 0.50JCC initially @ 90deg to determine any presence of astigmatism on that axis. Step 3: The axis of the JCC must straddle the axis of the correcting cylinder in the trial frames, in both flip positions.
Jackson's cross cylinder: used to check the power and axis of a cylindrical lens: Maddox rod: used to test for latent squint and retinal function Refraction box: has lenses of different powers for refraction testing: Slit lamp bio microscope: used for examining the anteriorly placed structures the eye; video link: Charts for vision - •Distant ...
Jackson cross cylinder of +/- 0.25 diopter. Jackson cross cylinder is a single low power lens, which is a combination of a plus cylinder and a minus cylinder of equal power with axis perpendicular to each other, with a handle placed between the two axes at 45 degrees.
Hopefully, after this, the eye will focus all light on the same location at the retina, and the patient's vision will be less blurred. [medical citation needed] In against-the-rule astigmatism, a plus cylinder is added in the horizontal axis (or a minus cylinder in the vertical axis). [18]