Accommodative Insufficiency: A Guide for New ODs
13:51Let me set the stage with a classic patient presentation.
10 year old patient complains of distance blur at school. When you ask a few more questions, they also state that sometimes when they are reading they have headaches or blurry vision. Sometimes they even tell you that their distance vision is blurry after they read (though it is rare for a young child to be this perceptive).
When vision is checked, acuity is typically 20/25 to 20/40 unaided. Usually worse at distance than near, but they read the 20/20 line really slowly up close. Their ending prescription is anywhere from +0.50 (low hyperopia or far sightedness) to -0.50 (low myopia or near sightedness), but the 20/20 line is still hard for them to read. Note: I know ODs out there know what I mean when I say myopia or hyperopia, but I am including the other terms for all other readers to the blog!
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| Kids and the phoropter: not exactly a match made in heaven. Best to not confuse things too much with subjective testing that is difficult to understand (like phorias or fused cross cylinder). |
Then you switch to near testing. Depending on the patient, only certain tests yield good results. Cover test is normal (most kids don't do well with phorias and vergences!). You might be able to get a binocular fused cross cylinder on older children if you are lucky. The responses vary. My two best tests are NRA/PRA and near retinoscopy (such as MEM). Classic NRA/PRA readings are low usually on both plus and minus blur points. They typically do very poorly with PRA (the minus blur points). You can of course also do an accommodative facility test (with the +2.00/-2.00 flippers and a timer), but in the real world this test is very time consuming to perform in a routine exam.
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| Near Retinoscopy: I should do it more that I do -- lots of great information can be gleaned. But I don't have these cards in every exam room, so I typically rely on NRA/PRA results and then trialing loose lenses at near subjectively. |
Then I like to demonstrate with loose lenses to the patient. Get them out of the phoropter as soon as possible! Let them hold a near card or reading material. Hold up a +0.75 lens and see their response. It is usually quite dramatic. Now sometimes the kid just wants glasses, so hold up a -0.75 or -1.00 and see what happens. If they are really having accommodative issues, they aren't going to like this at all. I will often show the patient what happens when they switch from near to distance with the lens to demonstrate that the glasses are only good for up close.
Prescription wise, I typically Rx +0.75 to +1.25 depending on the patient's distance prescription. The hardest part in all of this, of course, is telling the patient's parents why they need glasses. I always talk about Vision Therapy as an option too, but in my area, it is very expensive and of course not covered by insurances. I always explain that the glasses are for reading only (any near activity they are going to perform for longer than 10 minutes). A near activity I define as anything they are holding closer than arm's length. That means they are going to have to take the glasses on and off at school, but believe me this goes over much better than telling them they need bifocals. Here is my general discussion:
The focusing system of the eyes is made up of the eye muscles and a structure called the lens that the eye muscles control. When you do near work like reading, the eye muscles have to work to bring the image clear. Sometimes those eye muscles get tired, especially with so much near work at school like reading and math worksheets or tests. If you are straining those muscles up close, then they can get locked up in that position, so when you look across the room at the board, it will appear blurry too! The glasses I am prescribing are to relax how hard your eye muscles are having to work up close. Your child doesn't have bad vision, and doesn't need glasses all the time. They only need these glasses for near activities to reduce strain. In most cases, as the eyes continue to develop, they will no longer need these glasses over time. We will check the prescription and their need for near glasses every year at their annual exam.
I hope this helps. Telling a parent their child needs glasses is difficult in any situation, but when you tell them they need glasses for near when they have been complaining to mom and dad for months their distance vision is blurry, it is even harder. Most parents only know myopia (or near sightedness), so any other use of glasses seems strange. Again, especially when their child is coming home complaining of distance blur! I always like to tell parents that studies have shown myopia can be related to eyes being over-strained at near, so hopefully the use of these glasses can help with delaying myopia onset. If the parent is near sighted, they will appreciate any efforts to prevent their child from having a large myopic prescription. In a future post I will detail a patient's guide to accommodative dysfunction to hopefully make things easier for parents to understand!
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4 komentárov
That is a good idea to also show the -0.75 to rule out malingering.
OdpovedaťOdstrániťI typically do the NRA/PRA on anyone that complains of blur at near/distance after looking at the other distance for an extended period of time. The tricky thing is, a lot of patients need around a +0.50 ADD to balance the NRA/PRA. Clearly single vision reading spectacles are the best way to approach that, but the inconvenience of having to remove them all of the time isn't the best either. So typically I tell them to wear them when doing the near work for extended periods of time, but if you are at school taking notes, you might be able to avoid it during class, but will definitely need them when studying. The only reason I say this is to avoid the hassle of the constant taking off/putting on glasses. And most bifocals won't get cut in less than +1.00. Our lab sometimes will do a +0.75, but we end up having to bump it up and then they need to look through more intermediate, which I guess can be okay.
I liked how you approached the subject with the parents though. It was down to earth and not full of jargon, which can be tricky when you deal with the jargon every day.
I agree with you that the act of wearing near glasses can be quite difficult. I typically do have the kids bring their glasses to school for test taking, or if they are having an extended reading period in class. Otherwise, I agree that having them take their glasses on and off at school becomes too much of a hassle to make it worth their time. Homework and studying is a must for these glasses, so much more important to wear them at home. I typically avoid bifocals unless it is absolutely necessary due to issues with getting exact prescriptions and patient compliance. It is not easy to get a child to wear a bifocal unless their vision complaints are very high. I wish I had access to Essilor's anti-fatigue lenses (with around a +0.67 add) but the price tag on a lens like this is so much more expensive.
OdpovedaťOdstrániťWhat if the patient presents with more than -0.50 DS at distance? Patient was 20/70 and 20/50 uncorrected at distance and the end refraction was -1.00 and -0.75 with 0.25 cyl, respectively. Her PRA was significantly reduced to -1.00 with normal NRA value of +2.50. Would you have prescribed a bifocal or simply just have the patient remove glasses for reading for convenience?
OdpovedaťOdstrániťAs you can imagine - it depends! At school patients will be unlikely to take their glasses off and on for near work so if I am concerned about accommodative dysfunction I feel that's the least effective option. Listen to your patients symptoms, test their lag of accommodation, and prescribe based on the collective data! I never use just one test result to make this decision.
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