This examination could be performed either by an ophthalmologist or by a low-vision professional (optometrist).
The examination should include:
- Refraction and slit lamp examination.
- Best-corrected visual acuity – distance and near (using ETDRS chart).
- Visual acuity with an external telescope (x2.5) – distance and near (using ETDRS chart).
If the results of these tests meet the criteria for OriLens implantation, (three lines improvement for distance or for near) the patient is a candidate for further investigation and pre-op evaluation before implantation.
Feel free to use the form below as a guideline for the examination.
The form can be downloaded in PDF format, saved and printed by clicking here.
Patient selection form
Optical testing guidelines:
External telescope visual acuity testing:
Test one eye at a time while the other eye is covered.
A. External telescope testing
Visual acuity with an external telescope should be measured using regular ETDRS charts and a regular Galilean external telescope of 2.5X magnification.
The information collected by using the external telescope test is very important and should be taken into consideration in making the decision whether or not to implant the OriLens.
Place the telescope over the patient’s distance correction in a trial frame or a clip on (while the other eye is covered). Because the telescope reduces the amount of light, it is vital to illuminate the chart well, using a lamp placed about 1 meter away.
Ask the patient to locate the first letter on the top line of the chart. This is sometimes difficult. While s/he adjusts to the telescope, help by illuminating the letters and then find his/her vision ability with the telescope.
While the patient uses the telescope, explain that it provides only a sense of the magnification and discuss the differences and the visual field to be expected with the OriLens.
Repeat the same test for near reading. Adjust the telescope for near and perform near vision ETDRS test with the telescope.
Emphasize that the OriLens would be more comfortable, as it moves with the eye, thus providing a large functional visual field with natural eye scanning.
B. Subjective external telescope examination
Some patients do very well with an acuity chart but perceive less benefit for real-world objects.
At a distance of about 1.5 meters, have patients look at faces while an assistant repeatedly puts on and takes off the telescope. Ask him/her to compare the sense of which is better – with which they see more details.
While the fellow eye covered, have the patient watch television from the 2-3 meters distance, in order to demonstrate the magnification and the visual field. Ask the patient to compare the visual quality of the image, with and without the telescope.
Again, emphasize the advantage of the OriLens – the use of natural eye scanning.
C. Second eye exam
Perform the same procedure for the second eye while the first eye is covered.
Compering the amount of improvement for distance and for near for each of the two eyes will help to decide in which eye you are going to implant and which eye will demonstrate the maximal amount of improvement that the patient can expect to get in this specific eye.
D. External telescope use in selecting the eye to be implanted
Based on the information that is collected, a decision should be made as to which eye will be implanted.
The decision should be based on the ETDRS test and subjective examination. The eye, in which the patient feels more comfortable, will be an indication for the eye to be implanted.
If possible, determine which was the dominant eye and if there is no big difference, the dominant eye should be chosen as the first operated eye.
When the patient cannot assess the differences between the two eyes, then the information derived from the visual acuity examination will be taken into account and if possible the dominant eye will be operated.