Journal of Pediatric Ophthalmology and Strabismus

Eye to Eye 

Management of High AC/A Ratio Esotropia

David G. Morrison, MD; Scott E. Olitsky, MD; Edward L. Raab, MD, JD

Abstract

Nelson: Today’s topic is management of high AC/A ratio esotropia. The first case is a 3-year-old child who presented with esotropia of several months’ duration. The visual acuity was 20/30 in each eye with pictures, esotropia of 15 at distance and 30 at near, and cycloplegic refraction of +2.00. How would you treat this patient and then follow up?

Olitsky: The vision is good and the child has a normal level of hyperopia for this age. Looking at the distance to near disparity, we know that it’s probably going to respond fairly well to a correction of a relatively low amount of hyperopia. I would put this child into full cycloplegic refraction.

Nelson: Let’s say that you did not give the bifocal initially and he comes back with esotropia of 8 at distance and 18 at near with the glasses on.

Olitsky: I would observe this patient and assume that the esotropia at near was something that would get better with time.

Nelson: If the patient had an esotropia of 6 at distance and 12 at near with the glasses, would you treat him the same?

Olitsky: Yes.

Nelson: Dr. Morrison?

Morrison: I would give the full cycloplegic refraction to begin with, but I would initially give a bifocal. The AC/A ratio would be 7.5 for a +2.00 to correct the distance deviation fully. With that ratio, I think that a bifocal will likely be necessary to control the near deviation. In my practice, it seems easiest to have as much correction in the glasses as possible from the beginning and the parents seem to feel like they’re doing well if you can take the bifocal out subsequently. But if you want to add it in 3 to 4 months, not only is there the cost of the new lenses, but there’s an appearance that the child is not doing as well with therapy. So I would prescribe the bifocal and then if the AC/A ratio corrected or the deviation at near through the top segment was better than I’d hoped for, I could always remove the bifocal later.

Nelson: Dr. Raab?

Raab: I would give the bifocal initially. My approach when dealing with what I think is an accommodative esotropia is to knock out all accommodative effort initially and pull back later. I’m not bothered by the fact that the parents will be disappointed if you add it later, although that is a factor, so that does not determine what I do.

Nelson: Is there any time that you would consider not giving the bifocal with a difference between distance and near?

Raab: If the numbers had been 15 and 20 or 22, I probably would not give the bifocal. I don’t know what the hesitation is in giving the bifocal. To me the big hurdle is getting the child to accept and the parents to enforce glasses in any form. I think he can’t be harmed by the bifocal, but he could be harmed by not having it.

Olitsky: There are many reasons to give a bifocal, but not in a child who is fusing at distance. Data suggest we may not need to give a bifocal in that situation. Although we can debate whether giving the child a bifocal will help, I do not think there are any data to suggest that by not giving it there is a chance of hurting the child.

Nelson: What happens if you decided not to give a bifocal and this child comes back and still has a residual esotropia? The parents report that he closes one eye every time he’s…

Nelson: Today’s topic is management of high AC/A ratio esotropia. The first case is a 3-year-old child who presented with esotropia of several months’ duration. The visual acuity was 20/30 in each eye with pictures, esotropia of 15 at distance and 30 at near, and cycloplegic refraction of +2.00. How would you treat this patient and then follow up?

Olitsky: The vision is good and the child has a normal level of hyperopia for this age. Looking at the distance to near disparity, we know that it’s probably going to respond fairly well to a correction of a relatively low amount of hyperopia. I would put this child into full cycloplegic refraction.

Nelson: Let’s say that you did not give the bifocal initially and he comes back with esotropia of 8 at distance and 18 at near with the glasses on.

Olitsky: I would observe this patient and assume that the esotropia at near was something that would get better with time.

Nelson: If the patient had an esotropia of 6 at distance and 12 at near with the glasses, would you treat him the same?

Olitsky: Yes.

Nelson: Dr. Morrison?

Morrison: I would give the full cycloplegic refraction to begin with, but I would initially give a bifocal. The AC/A ratio would be 7.5 for a +2.00 to correct the distance deviation fully. With that ratio, I think that a bifocal will likely be necessary to control the near deviation. In my practice, it seems easiest to have as much correction in the glasses as possible from the beginning and the parents seem to feel like they’re doing well if you can take the bifocal out subsequently. But if you want to add it in 3 to 4 months, not only is there the cost of the new lenses, but there’s an appearance that the child is not doing as well with therapy. So I would prescribe the bifocal and then if the AC/A ratio corrected or the deviation at near through the top segment was better than I’d hoped for, I could always remove the bifocal later.

Nelson: Dr. Raab?

Raab: I would give the bifocal initially. My approach when dealing with what I think is an accommodative esotropia is to knock out all accommodative effort initially and pull back later. I’m not bothered by the fact that the parents will be disappointed if you add it later, although that is a factor, so that does not determine what I do.

Nelson: Is there any time that you would consider not giving the bifocal with a difference between distance and near?

Raab: If the numbers had been 15 and 20 or 22, I probably would not give the bifocal. I don’t know what the hesitation is in giving the bifocal. To me the big hurdle is getting the child to accept and the parents to enforce glasses in any form. I think he can’t be harmed by the bifocal, but he could be harmed by not having it.

Olitsky: There are many reasons to give a bifocal, but not in a child who is fusing at distance. Data suggest we may not need to give a bifocal in that situation. Although we can debate whether giving the child a bifocal will help, I do not think there are any data to suggest that by not giving it there is a chance of hurting the child.

Nelson: What happens if you decided not to give a bifocal and this child comes back and still has a residual esotropia? The parents report that he closes one eye every time he’s reading or looking at something up close.

Olitsky: I think that patient is better served by surgical management.

Raab: My reasoning is that I don’t want to see persistent over-convergence if I can get rid of it. My concern is that the tone of the medial recti will become altered and result in contracture, and that could influence even the distance deviation.

Olitsky: I think that’s an excellent point, but if you look at Dr. Parks’ study of patients with bifocals and their decompensation according to AC/A ratio and how large the esotropia was at near, theoretically it should have all been the same (Ludwig IH, Parks MM, Getson PR, Kammerman LA. Rate of deterioration in accommodative esotropia correlated to the AC/A ratio. J Pediatr Ophthalmol Strabismus. 1988;25:8–12). So I agree, but I don’t think a bifocal necessarily stops that from happening anyway.

Raab: I was a fellow of Dr. Parks and I’m familiar with that study, but my experience is that the AC/A ratio, or distance to near comparison, is not solidly connected to the rate of decompensation (Raab EL. Etiologic factors in accommodative esodeviation. Trans Am Ophthalmol Soc. 1982;80:657–694).

Nelson: So if you observe these children with 15 or greater near fixation, what happens? Do any of them eventually decompensate?

Olitsky: Some do, but in my experience a large percentage of them get better over time. As they do in the bifocal. I’m not sure that the bifocal changes the ultimate outcome.

Nelson: As a fellow of Dr. Parks myself, I remember asking why you give a bifocal. You show a child something up close and he immediately will raise his chin just enough to look through the bifocal without anyone having told him to do that. To me, there seems to be a tremendous benefit for that child who was esotropic at near to use the bifocal.

Morrison: The constancy of the deviation may play a significant role in that some of the children are a 15 at near and are intermittent and are fusing on a Worth 4-dot test. That’s a different situation than someone who’s constantly misaligned with near fixation.

Nelson: The second case is a 3-year-old child wearing a +2.50 prescription with a +2.50 bifocal add for his highest ratio esotropia. He comes back and his visual acuity is 20/30 with pictures. He has an esotropia of 18 at distance and 30 at near and through his bifocal he’s still approximately 18. What would you do for this child?

Morrison: I would cycloplege the child again to confirm that I had him in the best glasses possible. If I did not find a change at that point, I would consider surgical correction. There are a few different options. You could operate for the near angle and potentially have an overcorrection at distance. You could operate for whatever angle you found without the glasses in place, knowing that he doesn’t have high hyperopia. You could prism adapt to be sure that the child could tolerate the near angle or you could perform a modest medial rectus recession for the distance angle and then do a Fadden procedure or some type of pulley surgery.I find that aiming for the near angle rarely overcorrects the child, but my experience is that some patients, usually children, have a large difference with the distance–near disparity that would be overcorrected at distance. So I would measure the child with and without the glasses and use prism adaptation to be sure he could tolerate the near angle, then aim for the largest angle possible.

Nelson: Dr. Raab?

Raab: I probably would re-refract just to be sure that surgery is now indicated, unless this has been done several times already and at least within the past 6 months or so. Although some say you should routinely refract two or three times a year, I have not found that to be important. This is most likely a surgical candidate. I would add 1 millimeter on each medial rectus recession to what I would do for the distance deviation. This is not the highest distance–near discrepancy. I don’t think adding a millimeter here, taking an intermediate number, or operating for the near angle will make much difference.

Nelson: Dr. Olitsky, I know you don’t believe in bifocals, so you would have operated on this patient sooner. But in this scenario, what would you operate for?

Olitsky: I always operate for the near angle.

Nelson: The next case is a 3-year-old child with normal vision for his age. His eyes are absolutely straight at distance and he has an esotropia of 35 prism diopters at near. The cycloplegic refraction is +0.50. Dr. Olitsky, what would you do in this case?

Olitsky: I would just observe this patient.

Nelson: Dr. Morrison?

Morrison: I would put the child in a bifocal first, with the +0.50 on the top and the +3.00 on the bottom.

Nelson: Let’s assume that you did give the bifocal and he comes back and his eyes are still straight at distance. He has an esotropia of 35 at near, which is 25 with the bifocal.

Morrison: At that point, I would consider surgery, depending on how well the child was using the bifocal. If the parents told me the child’s compliance with the glasses was poor and there was no spontaneous bifocal use, I would consider a longer trial of the glasses before surgery in a child who is maintaining fusion at the distance. But if the child was wearing the glasses well, I would consider surgery after prism adaptation.

Raab: I think this case is a better example of what I was saying before. This is a 3 year old and his world is right around him, so he’s going to be converging and I’d be concerned that the zero at distance is not going to remain that way for long. So I would put him in a bifocal, although I more typically give +2.50 and not +3.00.

Nelson: I usually do a +2.50.

Raab: We both got that from Dr. Parks. In this case, I would probably try to give him even more than that, although I don’t have a strong rationale for that. I might give him a +3.50. I wouldn’t expect that to get him straight either, so we’re back to the same question that you asked Dr. Morrison.

Olitsky: Although I probably would not do this, this is a patient who might be best helped by surgery because a bifocal is going to set him straight in a very narrow area. He’s got a high AC/A ratio and his eyes will cross with anything closer than he can use his bifocal, whereas surgery potentially gets him straight everywhere. So surgery might be the best option for this patient.

Nelson: Let’s assume that you do operate on this patient. Do you ever see a situation where there’s a problem at distance so that it becomes overcorrection?

Morrison: I have seen it in an older child who failed to spontaneously improve the AC/A ratio over time. The child was still wearing a bifocal, was unable to taper, and had real difficulty at near and some frank diplopia without the bifocal. I’ve also seen children with prism adaptation who have been 30 exotropia at distance to the prism and others who seemed to respond to the prism adaptation but were still exotropic at distance afterwards. They’re rare, but I like to identify them ahead of time.

Nelson: Dr. Raab, would you be concerned about overcorrecting this patient at distance?

Raab: I’ve never faced a case like this and I certainly would be concerned about it. I’m not a big fan of posterior fixation, particularly on small eyes and medial recti. But for this patient I would consider a somewhat modest recession with a posterior fixation.

Nelson: The final case is a 3-year-old child with highest ratio esotropia who underwent a 5-mm recession of the medial recti muscles several months ago. He returns 2 months later and his visual acuity is still 20/30 in each eye. Prior to surgery he was wearing a +1.50 and a +2.50 bifocal add. Now his eyes are absolutely straight for distance with the bifocal and near without the use of the bifocal. How would you deal with the bifocal?

Raab: I would prefer to confirm that, again thinking that the harm from having it when he doesn’t need it is probably remote. But if that were the case, I would not completely remove the bifocal but reduce it by half.

Nelson: Let’s say you did initially follow him and he comes back several months later. His eyes are still straight at distance and near with the glasses.

Raab: That would influence me to remove the bifocal.

Nelson: Dr. Olitsky, I know you don’t give bifocals, but let’s say this patient was referred from someone else. What would you do?

Olitsky: I would explain to the parents that one option is to remove the bifocal, but I wouldn’t tell them they had to do it.

Raab: If we removed the bifocal, I would tell them not to get a new pair of glasses. There’s a small chance we may have to go back to them, so keep them in a drawer.

Morrison: I would take the bifocal out and leave him in the +1.50. I would also tell the parents not to throw the glasses away because we may need them again.

Nelson: What if the patient comes back 2 months later and he’s straight at distance and has an esotropia of 10 prism diopters at near above his bifocal? He’s still wearing the same glasses he was given prior to surgery.

Raab: I don’t think he’s going to need the whole +2.50, so I would titrate and see what he needs. I don’t think you would give less than +1.00 or +1.25.

Nelson: So at that 2-month follow-up, you would change his glasses accordingly?

Raab: Yes, but not necessarily remove the bifocal. I’m a bifocal believer.

Nelson: Dr. Olitsky, how would you handle this situation?

Olitsky: Exactly the same way. They could change it if they want to.

Nelson: Dr. Morrison?

Morrison: At that point, I would probably leave him in the same glasses. I think there may be drifting to come. Certainly if the esotropia at near is sneaking back that quickly, I would say if you haven’t gotten the new single vision lenses, just keep your bifocal for now and let’s watch this a little more.

Nelson: But if you had performed the surgery, you would not have told them at that point to get new glasses. You were waiting to see him in follow-up. Now you’re seeing him in follow-up and he has an esotropia of 10 at near above his bifocal.

Morrison: I would hold on to the bifocal.

Nelson: Thank you all for participating.

10.3928/01913913-20120621-01

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