Hints of Subjective refraction

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 Verify sphere in Subjective refraction

 Ask patient to look at the smallest line that they can see clearly.
 Verify sphere by offering ± DS (usually ± 0.25DS to fine-tune but may need ± 0.5DS if poor VA).
 Ask patient (Is the line clearer and easier to read with lens 1 or 2) ….!!???
 Do not make the prescription more minus if the lens does not improve the number of letters than can be read and just makes the already read letter to look ‘darker.
 always Put higher power lenses at back of trial frame.
 measure and document back vertex distance (BVD) especially if > ± 4.00 DS.

Ask patient to look at a rounded target/easily readable such as ‘O’ or dots.
 Use cross-cylinder (± 0.25D cross-cylinder, or ± 0.50 or ± 1.00 D if VA poor).
 Align handle with axis of trial cylinder.
 Ask patient (Is the circle rounder and clearer with lens 1 or 2)….!??
 Rotate trial cylinder towards the preferred cross-cylinder position respecting its sign(plus trial cylinder is rotated towards the plus sign of the cross-cylinder).
 Try not to remove the cross-cylinder from in front of the eyes as you rotate the axis and explain to the patient it will be clearer without this lens.

Once there is no difference between the two positions with the cross-cylinder handle along the axis of the cross-cylinder, repeat the procedure but with the handle at 45° to axis of trial cylinder. This will offer ± 0.25D cylinder.
Add the sign of the cylinder preferred in 0.25D steps until there is a reversal.
Add 0.25 DS for every 0.50 DC lost.

Plus 1.00 blur test (should reduce a VA of 6/5 or 6/6 to about 6/12……..if not, add more plus).
Duochrome test (monocular and binocular; aim for no preference/ slight red preference in myopia and green preference in hyperopia ).

most important if > ± 4DS.
Check near requirement at usual reading/working distance according to patient preference and occupational requirements.
If presbyopic (typically over age 45y), add a near addition suitable for the patient’s age and refine for the patient’s preferred working distance and working range.

Age 45–50y +1.00 DS
 Age 50–55y +1.50 DS
 Age 55–60y +2.00 DS
 Age >60y or pseudophake +2.50 DS

Significant change in axis or size of cylinder.
 Change of lens form.
 Overcorrection, especially of myopes who will end up permanently accommodating.
 excessive near correction resulting in an uncomfortably near and narrow reading distance.
 Unsuitable bifocal or progressive lenses( not fit for occupation,patient visual requirement