Identifying and Dealing with
Binocular and Nearpoint Vision Problems
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Studies show that the number of patients with binocular and nearpoint visual dysfunctions are growing.
Unfortunately, such problems are easily overlooked in busy primary care practices. Some of these patients are very sensitive to small differences in lens power, and are likely to complain that their glasses cause headaches or visual disturbances such as peripheral blur, headaches and lens rejections.
Admonishing patients with such delicately balanced visual systems to be patient and get used to their new Rx may leave them frustrated, since they may not be able to get comfortable with the new RX. Although some patients may learn to tolerate the new Rx, they may ultimately abandon your practice over their dissatisfaction with the prescription.
Some of the more serious binocular vision problems are amblyopia, strabismus, and convergence insufficiency. Vision problems like these can interfere with reading, concentration and even learning and are also on the rise but also frequently go undetected. Part of this may be that a doctor is uncomfortable working with youngsters, or hasn’t the time to take an extended history or to do additional testing that would reveal the problem.
In those instances, the cost to patients can be high. For example, a child with crisp distance acuities and Convergence Insufficiency (CI) who does not receive treatment will suffer through their school years, or worse, decide to stop trying. Poor academic performance lowers self esteem and is associated with high dropout rates and behavior problems. Today, not doing well in primary school is a recipe for an impoverished life.
Incorporating Screening into a Busy Practice
Most busy practices have staff doing pre-testing, so the doctor can add a few simple screening tests to their normal battery. Testing such as the double vision test card can demonstrate the appearance of overlapping words that the patient may experience toward the end of the day. The Brock string screening for suppression test may uncover amblyopia or strabismus in a relatively quick fashion. A red green reader bar held over a printed passage, with the patient wearing red green glasses will also indicate suppression if the patient is unable to read the words under one or the other of the color bars.
Another test that can be administered by a trained assistant is to use a pencil to determine at what distance (with and/or without correction) the person feels discomfort. If the distance is further than the patient’s habitual reading distance, the patient may benefit greatly from a reading Rx. In addition, remember that reading at arms length is much closer for a child than for an adult. Train the tech to notice if the patient leans away as the target gets closer, it is where the discomfort occurs that is most telling.
The results of these and other simple screening tests by the pretest technician give the doctor a heads up that more testing is in order, or that they may have to be more deliberate in developing an Rx. For many people, children in particular, the doctor may find that lenses alone are not going to be enough and that a referral for vision therapy is in order.
Many doctors make such recommendations but find patients do not comply. There may be a financial, time or insurance issue. However, in some cases, for example with a child referral, the parent just has not understood how vision could be causing problems with reading, comprehension or even motion sickness and headaches. A few demonstrations can quickly make the case that the parent should comply.
Double Vision Demo: Show the parent the same card used in pretest. Ask the child if the doubled image is what they see when at school or reading—especially toward the end of the day when they’re tired. When the child says yes, turn the demonstration card to the parents and explain, “This is how your child’s books look. Can you imagine how hard it would be to sit through school all day if every book and worksheet looked like this?”
Up-Down Reader Demonstration: This is the easiest way to show the link between vision and comprehension. This card has several sentences arranged vertically, starting up the page, over a column, then down, over a column and then up and so on. Have the parent read it aloud. Most people start fast, then quickly slow down as they struggle to move their eyes in this unfamiliar way. Point out slow or hesitant reading and ask if that’s what the patient sounds like when reading. After the third or fourth sentence is read, stop the patient and ask them to tell you what the sentence before last said. Very few can do this. Explain “All I have done is make it as hard for you to move your eyes up and down as it is for your child (or adult patient) to move their eyes from left to right. You can see how that eye movement problem completely disrupts comprehension.”
Referrals
If you are not offering vision therapy yourself, tell the parent that you have found a problem that will require more to resolve than the lens you’re prescribing today. Say that you are referring them to an optometrist who deals with problems with focusing, aiming, using the eyes as a team, suppression, amblyopia, strabismus, etc, that you found. If you can, link the findings to things like a nightly homework battle, attention problems, reversals, visual memory problems such as inability to recall spelling words, etc.
When turning the patient over to a technician, tell the assistant that you are referring to another doctor for binocular vision assessment and treatment. Explain to the parent or patient that you will have the assistant call the other doctor to set up an appointment if they wish.
Most vision therapy providers are happy to work out a protocol with you for referral that includes reports and return of your patient (and their family) for primary care and for lens prescriptions. In 30 years of working with VT optometrists, I have yet to find one that isn’t diligent about returning patients for primary care, often with praise that the primary care doctor is very good if they found this binocular vision problem.
For many patients with nearpoint problems, the difficulty can be that they are over accommodating, with the neural overflow affecting vergence. In other words, they are not aiming their eyes exactly where they are focusing. For many such patients, the answer lies in special purpose lenses. And that often means multiple pairs are required since it is nearly impossible to make one Rx cover all visual activities.
Low plus lenses are often misunderstood. How is it that a half diopter of plus (or half D less minus) makes a significant difference? As neuroscience has focused more on the visual system, it has become clear that the effect of the plus is not on the eyes so much as on the brain. The low plus (particularly for the esophore) actually quiets down the neural overflow of excessive accommodative signals so vergence is relaxed. Often the amount of plus required to accomplish this is very small, roughly the dioptric value of the lag (difference between the distance at which the patient is focused, and where their eyes are aiming).
One of the best and most practical ways to learn about low plus (often called relaxing or occasionally learning lenses) is to keep a few flippers on hand with very low plus. My own set includes .25, .50, .75 and 1.00 lenses. If patients are affected by small differences in lens power, pull out the flippers, give the patient a near reading card and with their distance Rx on, drop and lift the flipper in front of them as they read. Try several powers. In many cases you will hear rapid changes in reading rate or smoothness.
If the patient is a child, ask parents if they hear a difference. Ask the patient, “Does it feel better when the lens is there?” I suggest you tell such patients that you are going to recommend this additional lens because it makes a difference for them. It is their choice whether to get it or not, but seeing/hearing/feeling is believing and many patients will accept the multiple recommendation and love you for it. This kind of examination is needed for adult patients by the way, because something like a quarter of all people have this kind of problem and if untreated, it persists into adulthood.
There is much more to dealing with the huge population with nearpoint and binocular vision problems, but these suggestions may be helpful in organizing the practice and alerting the doctor and staff to their presence. Attending to these patients is satisfying not only at a professional level, but it is also rewarding financially.
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