Performing Refraction Post-Op

Female ophthalmologist determines diopterPatients may need eyeglasses in order to see a focused image on the retina after OriLens implantation.

The final post-op refraction is affected by three optical elements: the cornea, the implanted cataract lens (in the capsular bag) and the OriLens.

It is impossible to perform regular refraction by an auto-refraction for eyes with an implanted OriLens.

The Post-op refraction of an eye with an implanted OriLens depends on the pre-op eye parameters (mainly the K reading) plus the impact of the new implant.

The table below shows the theoretical (computer calculated) post-op refraction after OriLens implantation.

The table assumes that the regular in-the-bag IOL, which was implanted before the OriLens was inserted, completely compensated for the cataract surgery and the eye became emmetropic.

 

How does it work?

Find the line that indicates the pre op average k reading and find the calculated dioptric power range for the refraction of the eye post-op.

For example: an eye that had an average K reading of 44.00 and was emmetropic after the regular IOL was implanted, will have a post op refraction induced by the implantation of between -0.76 to -2.44 diopters.

 

Pre OP Average
K Reading In
Diopters
Post Op Range of
Dioptric (distance)
refraction
40.00   Diopter + 2.62  to   +0.91
41.00   D +1.75   to   + 0.07
42.00   D +0.93   to   – 0.76
43.00   D + 0.08  to   – 1.60
44.00   D – 0.76    to   – 2.44
45.00   D – 1.61   to   – 3.27
46.00   D – 2.45   to   – 4.11
47.00   D – 3.29   to   – 4.94
48.00   D – 4.13   to   – 5.78
49.00   D – 497    to   – 6.61
50.00   D – 5.81   to   – 7.44

 

As can be seen from the table, the induced refractive change that can occur as a result of the implantation, is limited to mild myopia or hyperopia.

The table was calculated for all relevant eye parameters (Axial Length between 20.00 to 30.00 mm, ACD between 2.50 up to 4.00 mm and K reading between 40.00 D to 50.00 D).

We analyzed their effect and found that ACD and AL have little effect on the post-op refraction, assuming that the eye was emmetropic after the regular IOL was implanted.

This is the reason why the above table with only the K reading figures can be used to estimate the post-op refraction.

Since the table above assumes that the regular IOL that is implanted before the OriLens, renders the eye to become emmetropic, if the eye is not emmetropic after the cataract implantation, you should make the appropriate adjustments.

Do not forget to correct any existing astigmatism (corneal or surgical induced).

For reading add +3.00 D as usual.

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