Doctor's Answers (4)
And then the optometrist will do their own spectacle power check, with and without dilating drops if this is a pre-LASIK check.
And so, with all this information at hand, we can imagine a few scenarios.
eg. Patient says they have worn the same spectacles for 2 years, and that spectacle lens power (can be checked with lensmeters/focimeters in the office) is the same as the optometrist's own current refraction check, and any soft contact lenses have not been worn for at least the past week, then we can say the spectacle power is stable
or on the other hand
eg Patient says they just updated the glasses 6 months ago, and the optometrist's current refraction check is even higher than that of the updated glasses, then the spectacle power is probably not stable
As you can see, it depends partly on what the patient tells the optometrist, and partly on what the optometrist finds on examination. If there is any uncertainty about the stability of the spectacle power, it is usual practice to postpone LASIK until another spectacle power check in perhaps 6 months to 1 year.
To find out if the degree has been stable, the optometrist would obtain the history of the eye degree from the patient. If the patient's prescription has remained similar over at least 12 months, the vision is considered to be stable. However, minor fluctuations of 0.25 to 0.50 diopters would usually be accepted, as these may be contributed by eye fatigue or errors during subjective refraction.
If the patient could not remember his/ her eye degree or an eye exam has not been done recently, the optometrist would obtain the patient's latest spectacle or contact lens degree, and ask the patient the current quality of the vision when wearing those visual aids.
The key to diagnosis is in the history-taking when a patient comes in for a pre-LASIK evaluation. If a patient is seen the first time, an optometrist is able to gather some information on the patient's prescription stability. For example, patient's age, performance of current glasses, previous vision correction aids etc.
Certainly, a manifest refraction (degree check) would be performed and thereafter cross-checked with all the above information obtained. Should the optometrist has reservation on the stability of patient's prescription, it would be beneficial to then have another manifest refraction in few months’ time to ascertain stability before having LASIK.