Chief Complaint: Failed school vision screening
History of the Present Illness: This 5-year-old female patient presents for her first complete eye examination after a school vision screening found unequal visual acuity, with the left eye (OS) worse than the right eye (OD). Her parents have not noted any eye problems or abnormal visual behavior. The patient has never worn glasses or done any patching. The patient denies vision changes, double vision, eye pain, and other eye problems.
Past Ocular History: None
Past Medical History: She was born full term via uncomplicated spontaneous vaginal delivery after healthy gestation, and is meeting all normal childhood milestones. She has no history of any medical issues other than occasional upper respiratory infections. She is up-to-date on all routine immunizations.
Medications: None
Family History: No history of amblyopia, strabismus, or other ocular problems aside from refractive error
Social History: She lives at home with her parents and one older sibling.
Review of Systems: All systems negative
Stereoacuity testing:
Pupils: No relative afferent pupillary defect in either eye (OU)
Extraocular motility: Normal versions
Ocular alignment: Orthophoric at distance and near
Visual acuity by Snellen letters (at distance without correction):
Confrontation visual fields: No deficit OU by toys
Cycloplegic refraction:
External exam: Normal
Anterior segment exam
Posterior segment exam
The patient was diagnosed with anisometropic hyperopia and probable amblyopia OS, was given her cycloplegic refraction minus 0.75 D to encourage compliance, and was asked to return in two months for a repeat examination. At this return appointment, her visual acuity was found to be 20/20 OD and 20/60 OS at distance while wearing her new glasses. Her cycloplegic refraction was rechecked and found to be stable and accurate. The remainder of her complete eye examination was stable as well. The diagnosis of anisometropic amblyopia was discussed with her parents, and a trial of full-time occlusion therapy OD was initiated. The patient was scheduled to return in 1 month.
At the return appointment, the patient’s mother reported that although her daughter didn’t terribly mind patching, they had not been patching more than a few hours a day. Polite yet frustrated, she reported that she had been reading about amblyopia on the Internet, that many other parents on the “message board” didn’t have to patch their children more than a few hours per day, and that some said it was dangerous to patch the eye all the time.
This sample patient case brings up two important issues: the appropriate timing of occlusion therapy (full-time versus part-time), and the discussion of different treatment options during the consent process. Both of these items will be discussed in turn.
Differences of opinion and debate exist among pediatric ophthalmologists regarding the roles of part-time occlusion (PTO) versus full-time occlusion (FTO) therapy in the management of amblyopia. Our institution has long been a proponent of FTO, and we believe that appropriately-monitored patients treated with FTO have excellent outcomes. Supporters of PTO, by contrast, feel that less patching time is not inferior to FTO, and this treatment regimen has gained traction among pediatric ophthalmologists, particularly over the past decade.
Occlusion amblyopia, or the development of amblyopia in the originally better-seeing, patched eye, is a risk commonly cited by opponents of FTO. Recently published evidence, however, suggests that although the incidence of occlusion amblyopia in patients treated with FTO is admittedly significant (19.3%), it is almost always reversible; only 7 of the 597 patients treated, or 1.17%, developed occlusion amblyopia with a sustained fixation preference for the initially amblyopic eye. Final visual acuity in the eyes with occlusion amblyopia was at least 20/30. Furthermore, after cessation of treatment, the final interocular difference in visual acuity was actually less in children with a history of occlusion amblyopia, suggesting that occlusion amblyopia can herald a better visual potential in the initially amblyopic eye [1]. Both the incidence of occlusion amblyopia and its nearly-universal reversibility correspond well with data previously reported [2].
Others object to FTO on the grounds that it requires children to patch while at school, potentially subjecting them to teasing/bullying from peers. While definitely a potential obstacle, it has been our experience that this is not a commonly-cited parental concern, and that many parents note compliance is easier at school, where it can be monitored by a teacher. Certainly, if undue and intolerable social pressures are present, alternative arrangements (i.e. PTO) may be preferable.
Consistency is a strong, if albeit theoretical, advantage to FTO. Anecdotally, it is our experience that compliance issues seem more common in patients treated with PTO than FTO. For example, if four hours per day of occlusion therapy are prescribed, the patient and/or the parents will often attempt to “bargain” this amount down to a lower number. A child may act out when it is “time to put the patch on,” and continue his or her strenuous objections until the patch is removed. By contrast, if all parties understand that the patch is to be in place at all times, bargaining on the duration is no longer an issue and the child may be less likely to misbehave, as the patch is now “part of life,” and not just a transient nuisance for a few daily hours [2].
Evidence both anecdotal and statistical suggests that FTO results in more rapid improvement in visual acuity of amblyopic eyes than does PTO. One retrospective review, though of an admittedly small sample size (n=45), demonstrated a trend toward better visual outcome and more rapid improvement in patients treated with FTO versus those treated with PTO [3].
In order to help understand which treatment regimen was superior, the Pediatric Eye Disease Investigator Group (PEDIG) conducted two multicenter randomized clinical trials. Both trials studied patients younger than 7 years old with either strabismic or anisometropic amblyopia. One study included patients with moderate amblyopia (defined as visual acuity 20/40 – 20/80), while the second included those with severe amblyopia (defined as visual acuity 20/100 – 20/400). The former study compared prescribed patching regimens of 2 hours daily PTO to 6 hours daily PTO, while the latter compared prescribed patching regimens of 6 hours daily PTO to FTO [4,5].
The moderate amblyopia study found similar visual acuity outcomes at the intervals studied between patients prescribed 2 hours daily PTO and those prescribed 6 hours daily PTO. Specifically, they found that an equal percentage of patients in both groups had visual acuity of at least 20/32 or gain of 3+ lines of vision in the amblyopic eye at 4 months after initiation of therapy. Notably, however, there were more patients with visual acuity of 20/25 or better in the prescribed 6-hour PTO group at the time of last follow-up. This study led to the PEDIG recommendation that patients with moderate amblyopia be prescribed 2 hours of daily PTO.
The severe amblyopia study found similar visual acuity outcomes at the intervals studied between patients prescribed 6 hours daily PTO and those prescribed FTO. There was a slight improvement in visual acuity in the patched eye in the PTO group but not in the FTO group, but this difference was attributed by the authors to a learning effect, and felt to be unlikely due to occlusion amblyopia. This effect was transient and resolved on further follow-up. There were no differences between the two groups in terms of parent-reported ease of compliance or social stigma. This led to the PEDIG recommendation that patients with severe amblyopia be prescribed 6 hours of daily PTO. Because these studies compared prescribed patching duration and not what was actually performed, it is possible that the patients prescribed FTO actually wore the patch significantly less than full time, which would confound the results.
These PEDIG studies, as well as others involving the use of atropine penalization to treat amblyopia, received significant coverage in the national media.
To examine the effect of these media reports on parent preferences among different amblyopia treatment regimens, Golden and Olitsky distributed two articles from lay media to parents of pediatric ophthalmology patients, and asked the parents to rank their preferences among atropine, 2-hour PTO, 6-hour PTO, and FTO as potential treatments for their children. There was a strong preference for atropine therapy. After completing their initial rankings, these same parents received a separate fact sheet with additional details from the scientific studies on which the lay media reports were based; this information explained that patients treated with atropine were less likely to achieve the visual acuity treatment goals, that longer PTO intervals led to better and quicker outcomes, and that FTO was thought to lead to slightly better and quicker outcomes. After reading this additional information the parents were asked to re-rank the different regimens; doing so yielded a statistically significant shift away from atropine and toward increased patching [6].
The Golden and Olitsky study underscores the importance of lay media in creating opinions about scientific issues. By extension, it is easy to understand how a parent could be influenced by opinions and experiences of other parents whose children have been treated for the same condition. Additionally, the study demonstrates that parents are also able to assimilate scientific information relatively well and are capable of reforming their opinions when appropriate.
The process of informed consent applies whenever treatment is recommended. According to the American Medical Association (AMA), it involves discussion of the following elements:
This means that an appropriate discussion with parents upon initiation of patching therapy for amblyopia includes mention of both PTO and FTO. The provider may mention that different providers have different interpretations of the scientific data regarding how many hours per day the patch should be worn. The provider may mention that some feel that PTO and FTO are equally effective, but that FTO may yield quicker results, and that sometimes FTO may be easier to perform than PTO. The provider may mention that any patching regimen may lead to mildly decreased vision in the patched eye, which is almost always reversible and for which their child will be closely monitored.
In sum, there are differences of opinion among providers as to the optimal daily duration of occlusion therapy for treatment of amblyopia. Unsurprisingly, this leads to differences of prescribed patching regimens. These differences may create confusion on the part of well-meaning parents of children with amblyopia who attempt to research the topic online, particularly if the different options have not been discussed before instituting therapy. Some providers may feel that discussing treatment options they feel are inferior is a waste of valuable clinic time and may confuse the patient; nonetheless, the directive to discuss all alternative options is clear. Finally, if one can avoid non-compliance and parent dissatisfaction due to confusion regarding the treatment options, an ounce of prevention may truly be worth a pound of cure.
>Weed MC, Larson SA. Management of Amblyopia: Discussing Options for Treatment in the Age of the Internet. EyeRounds.org. September 9, 2013; available from https://eyerounds.org/cases/178-amblyopia-managementment-communication.htm
Ophthalmic Atlas Images by EyeRounds.org, The University of Iowa are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
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