Welcome to our presentation on using Ocutech’s Bioptic Prescribing Worksheet. We hope you will find this clinical assessment and prescribing guide helpful in your low vision practice.
A successful bioptic telescope prescription requires 4 general components. First that your patient has the appropriate goals for the use of the device- which are usually for seeing at distance and mid-range. Second, that their vision responds to telescopic magnification. Next, that they have or can develop the skills needed to use the device, and lastly that they are motivated to make the investment in time, effort, and finances to learn to use it and even to wear it in public.
Low vision experts find that their patients do most well when they can provide them with about 20/40 visual acuity through the device with a field of view of at least 10 degrees. Individuals are usually able to see everything they need to see when their visual acuity is 20/40 and can find what they’re looking for when the field of view is at least 10 degrees wide. Prescribing a higher power telescope to provide better visual acuity will be at the expense of a narrower field of view, which studies have shown, is the major concern of experienced bioptic users. So, as a result Galilean optical design telescopes can provide adequate fields of view up to about 3x power, while Keplerian optical design telescopes are generally preferred in powers 3x and above.
In consultation with experienced bioptic telescope prescribers, Ocutech has developed and tested this Prescribing Worksheet to help you determine a successful bioptic prescription. This presentation will take you step-by-step through the process with a discussion regarding the clinical reasoning at each decision point.
At the top of the form you’ll not only collect your patient’s basic demographic data, but also explore their distance and mid-range functional activity goals . As we know, low vision care is usually task oriented– there needs to be a specific activity your patient seeks to improve that can be addressed by the low vision aid. Many of these are listed at the top of the form, including seeing faces, watching television, and driving for example. Some of our patients however, won’t offer specific activity goals, but rather say, they just want to see better. Since distance vision is an important ‘social sense’ which helps us to see the world around us as well as to connect with others through eye contact and body language, wanting to “Just see better” suggests that they are feeling disconnected. Studies have shown that loss of distance vision contributes to feelings of isolation which may lead to depression to a greater extent than does loss of reading vision. Reading is an activity that can be replaced non-visually in many different ways. Distance vision, however, cannot be readily replaced by other means– no one can see one’s grandchildren, friends and family, cultural events, or the beauty of the world around them for them. While bioptic telescopes are intended primarily for distance and mid-range applications bioptics can often be used for near point activities, though these activities should not be considered a primary goal for use of the device.
Going down a little further on the worksheet you’ll see two ‘prognosis” columns on the right side. Each assessment factor will allow you to place a check in either the ‘good’ or ‘fair’ column. For the most promising prognosis we seek to have 5 or more checks in the good column.
So, lets get started. The prognosis for successful bioptic prescribing rests first with your patient’s best corrected distance visual acuity. It is very unlikely that bioptic telescopes will be beneficial for persons with visual acuity worse than 20/300. So, if acuity is 20/300 or better we can place a check in the good column and move to step 2, otherwise it’s best to stop right here and move on to exploring your patients other low vision rehabilitation needs.
As mentioned earlier, our goal is to achieve 20/40 while looking through the telescope and preferably that the better-seeing eye is dominant. Patients often find that it is difficult for them to localize targets through a telescope when using their non-dominant eye. A convenient way to determine the dominant eye is to ask the patient to look through a handheld monocular telescope to see which eye they reflexively take it to. If they ask which eye they should use, suggest they use whichever eye they feel is more natural. We hope of course that they will take the monocular to the better seeing eye.
A list of suggested powers for Ocutech telescopes based upon the patient’s visual acuity is provided. If you cannot achieve the acuity you expect, first make certain the device is properly focused or that an eyepiece correction is used if needed. Otherwise increase the power of the telescope. If 20/40 can be achieved in the dominant eye you can check the box in the ‘good’ column, record the power and eye to be used at the bottom of section 2, and then move on to question 3. If you cannot achieve 20/40 in the dominant eye even when using a higher power telescope move on to 2b.
If you cannot achieve 20/40 through the dominant eye, but can in the fellow eye, determine whether the patient can localize effectively using the non-dominant eye. If they can, check the 2b box in the ‘fair’ column, record the power and eye for the telescope you’re using, and move on to question 3. If they cannot localize effectively with the better-seeing non-dominant eye move on to question 2c.
Occasionally, when an individual’s best vision is in the non-dominant eye, occluding the dominant eye while using a telescope may offer some functional benefit, but usually the ability to localize targets through the telescope will remain reduced. Prescribing a binocular device, however, may overcome this dominancy conflict. In order to provide at least a 10 degree field of view, binocular prescriptions are usually limited to no higher than 3x. So, if a 3x or lower power telescope can provide 20/40 in either eye, a binocular prescription may be a promising option. In this case check the 2c box in the fair column, record the telescope power for the binocular prescription at the bottom of section 2, and move on to question 3. Frequently, when prescribing powers of 3x or less, binocular prescriptions will be preferred by patients irrespective of their dominancy, as they may experience a wider field of view, a more natural perspective, and often less fatigue. If there is no compelling binocular telescope option available, it is likely time to discontinue the telescope evaluation.
So, if your patient is responding to telescopes with promise, you should have now recorded your initial telescope power and whether you intend to prescribe to the right, left or both eyes at the bottom of section 2 . Remember, we much prefer to prescribe the telescope to be used by the dominant eye if at all possible. If not, consider a binocular option prior to prescribing to the non-dominant eye alone.
Section three explores your patient’s response to low contrast targets. While the visual acuity chart is high contrast, the world is not. Reading the eye chart well through a telescope is not a good predictor of how well your patient will see in the ‘real world.’ On the other hand, seeing a face well from across the room in normal room illumination will often be a better predictor of your patient’s visual response to telescope magnification. While we seek a robust response, where the patient reports that they can see the face much better, some individuals will report that they see the face larger but not better. Since all telescopes reduce retinal illumination and contrast, if your patient already has reduced contrast due to media issues, edematous retinas or optic nerve disorders, they may not receive the visual benefit we seek from the telescope. If they can see the face well, check the #3 box in the ‘good’ column and move on to question 4. If not, move next to 3a.
Ocutech’s VES Sport 4x telescope contains a larger objective lens than that contained in the 4x VES K or VES II. A larger objective lens will provide a brighter retinal image and this may be sufficient to better support the contrast needs of your patient. So, if you’re using the VES K or II, try using the VES Sport. If this improves facial visibility satisfactorily, then check the 3a box in the ‘fair’ column and move on to question 4. If the VES Sport is not helpful or is already being used, move on to 3b.
If contrast through the telescope remains insufficient, you can also try a lower power telescope. The lower the power the brighter the image may be, however this will be at the expense of reduced acuity through the telescope. If, while using a lower power device your patient can now see faces adequately from across the room despite the lower acuity of at least 20/60, check the 3b box in the fair column. Enter any changes to the telescope style or power you are considering here and move on to question 4. If your patient still cannot see faces well you may either choose to discontinue the assessment or suggest that the bioptic may be of most benefit when it is used in brightly lit and outdoor environments.
Question 4 reconfirms your patient’s visual activity goals. By referencing the choices selected at the top of the worksheet, confirm that a bioptic telescope remains appropriate for their personal goals. Place a check in the ‘good’ column if you feel a bioptic is still appropriate and move on to question 5. If your patient’s goals have changed, and a bioptic is no longer appropriate, it may be time to pursue their other visual activity goals.
Using a bioptic requires some skill by the patient. Learning to find and localize the target through the carrier lens, then translating their line of sight into the eyepiece to see it, to focus, track and keep their head still to prevent the image from jumping around, all require practice and patience. Children and younger adults often adapt readily, while seniors may encounter more difficulty. Of course, the higher the power of the telescope the smaller the field of view will be and the more the image will move due to head motion, so higher power telescopes may often be a bit more challenging to adapt to. If your patient readily adapts to using the bioptic place a check in the good column and move on to #6. If they are having difficulty go to 5a.
If during the telescope evaluation your patient is getting better at using the bioptic, then their prognosis to benefit from additional practice and training is promising. In this instance place a checkmark in the fair column and move on to #6. If they are confused, disoriented or not improving it is likely time to suspend the bioptic assessment.
Our patients need to be motivated to use a bioptic telescope. Some individuals are eager to use any low vision aid if it will help them to see better. Others prefer to not use something that looks unusual or that requires that they learn new skills. These are their choices and they are under no obligation to pursue any treatment option, no matter how helpful it might be. Usually, if you have a successful candidate it will be quite obvious. If you don’t there’s not much you’ll be able to do to impact the result. In the latter event, you might explain that their visit with you is to determine appropriate low vision options, and not necessarily to make any immediate decisions. If they are enthusiastic, place a check in the ‘good’ column and move on to finalize the prescription in item #7. If not, stop your bioptic assessment and explore other visual activity goals the patient may have.
If you have 5 or more checks in the ‘good’ column you should feel confident that you have a very promising bioptic candidate. Specify the device, power and eye or eyes you intend to prescribe for. The reverse side of the Worksheet lists all of the additional information you’ll need to collect to prescribe any Ocutech product . Each device has it’s own step-by-step order form to help you complete the order. Order forms can be downloaded from Ocutech’s website. If your patient is not yet ready to make a decision, we suggest that you collect all the information anyway and keep it on file in the event that they elect to order the system later. Ocutech’s website also offers narrated step-by-step fitting and prescribing demonstrations for each of its products.
If you have fewer than 5 checks in the good column, than while a bioptic may still offer some functional benefit, the prognosis for a successful prescription is more guarded and you should counsel your patient regarding the issues they may encounter that might impact their success.
Individuals with well circumscribed macular defects or those with central vision loss from genetic and developmental disorders usually respond quite well to bioptic telescopes. Individuals with Stargardt’s disease, albinism, nystagmus, achromatopsia and rod/cone dystrophies are especially successful.
Individuals with visual disorders that markedly reduce contrast or constrict the visual field usually do not respond to telescopic low vision aids.
Ocutech’s bioptic telescopes have been developed to provide the widest field of view available in a design that is comfortable to wear, and easy for the low vision specialist to fit, demonstrate, and prescribe. They can be readjusted even after dispensing and can be reused in the unlikely event that they are returned. In fact, Ocutech receives less than ½ of 1% of its products back for return. The development of Ocutech’s original VES products were funded with grants from the National Eye Institute and have been proven effective in independent NIH funded clinical trials.
Thank you for your interest. We hope that you have found this presentation to be helpful. We invite you to contact Ocutech to receive your copy of the Bioptic Prescribing Worksheet and to learn more about Ocutech’s full line of telescopic eyewear for the visually impaired.