Is it mandatory to treat amblyopia prior to surgery in esotropia?

Management of amblyopia in pediatric patients: Current insights

Amblyopia is a cause of significant ocular morbidity in pediatric population and may lead to visual impairment in future life. It is caused due to formed visual deprivation or abnormal binocular interactions. Several risk factors in pediatric age group may lead to this disease. Author groups have tried managing different types of amblyopia, like anisometropic amblyopia, strabismic amblyopia and combined mechanism amblyopia, with optical correction, occlusion therapy, penalization, binocular therapy and surgery. We review historical and current management strategies of different types of amblyopia affecting children and outcomes in terms of visual acuity, binocularity and ocular deviation, highlighting evidence from recent studies. Literature searches were performed through Pubmed. Risk factors for amblyopia need to be identified in pediatric population as early in life as possible and managed accordingly, as visual outcomes in amblyopia are best if treated at the earliest. Although, monocular therapies like occlusion or penalization have been shown to be quite beneficial over the years, newer concepts related to binocular vision therapy are still evolving.

Risk factors of strabismus surgery among pediatric cerebral palsy population with strabismus in Taiwan: A population-based cohort study

BACKGROUND

To identify the risk factors of strabismus surgery among Taiwanese children with severe cerebral palsy (CP) and strabismus.

METHODS

This retrospective nationwide population-based cohort study examined a cohort of newly diagnosed pediatric CP patients (age ≤ 10 y) between 1997 and 2013 with strabismus. The primary endpoint was strabismus surgery. A stepwise logistic regression was applied to determine the demographic factors, ophthalmic conditions, and comorbidities associated with strabismus surgery.

RESULTS

Out of 808 patients, 115 had received strabismus surgery. The significant factors correlated to strabismus surgery in pediatric patients with severe CP and strabismus were CP diagnosis age < 4 years, residency in a suburban/rural area, low birth weight, and strabismic amblyopia.

CONCLUSION

In CP children with strabismus who have risk factors of younger CP diagnosis age (age < 4 y), residency in a suburban/rural area, a low birthweight, and the presence of strabismic amblyopia, strabismus surgery should be considered.

Practice Patterns in the Management of Amblyopia: A Survey Study

PURPOSE

To characterize current practice preferences of pediatric ophthalmologists in the management of amblyopia and whether these are influenced by demographic variables.

METHODS

A 10-question survey was distributed to all pediatric ophthalmologists and fellows attending the Annual Joseph H. Calhoun Pediatric Ophthalmology Forum at Wills Eye Hospital in 2016. The questionnaire consisted of demographic information and clinical management of amblyopia using clinical scenarios commonly encountered in pediatric ophthalmology practice.

RESULTS

Of the 133 pediatric ophthalmologists who attended, 74 completed the survey, all of which were included in the data analysis. Seventy-six percent of respondents prescribed refractive correction to a 3 year old with untreated anisometropic amblyopia prior to initiating occlusion therapy. For a child with coexisting exotropia, 57% recommended refractive and occlusion therapy until significant visual improvement, then surgery; however, 30% would perform surgery earlier. Fifty-seven percent stopped occlusion therapy at 10 years of age or older. Sixty-four percent estimated a patient patching compliance rate of 50% to 75%. There was no significant relationship (P < .05) between any of the demographic variables, indicating that no group was more or less likely to respond to the question in any way.

CONCLUSIONS

This study highlights the lack of a unified approach to certain aspects of amblyopia management. Physician-related demographic variables did not significantly affect clinical decision-making; however, variation did exist among respondents, a finding that warrants further investigation. [J Pediatr Ophthalmol Strabismus. 2018;55(2):100-106.].

Strabismus surgery before versus after completion of amblyopia therapy in children

BACKGROUND

Normal visual development occurs when the brain is able to integrate the visual input from each of the two eyes to form a single three-dimensional image. The process of development of complete three-dimensional vision begins at birth and is almost complete by 24 months of age. The development of this binocular vision is hindered by any abnormality that prevents the brain from receiving a clear, similar image from each eye, due to decreased vision (e.g. amblyopia), or due to misalignment of the two eyes (strabismus or squint) in infancy and early childhood. Currently, practice patterns for management of a child with both strabismus and amblyopia are not standardized.

OBJECTIVES

To study the functional and anatomic (ocular alignment) outcomes of strabismus surgery before completion of amblyopia therapy as compared with surgery after completion of amblyopia therapy in children under seven years of age.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2014), EMBASE (January 1980 to July 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to July 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 24 July 2014. A manual search for articles from a review of the references of the selected publications and conference abstracts was completed to identify any additional relevant studies.

SELECTION CRITERIA

We searched for randomized controlled trials (RCTs) that provided data on strabismus surgery in children less than seven years of age, performed after initiation of, but before completion of amblyopia therapy, as compared with strabismus surgery after completion of amblyopia therapy.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies identified from the electronic and manual searches.

MAIN RESULTS

There were no RCTs that fit our inclusion criteria and so no analysis was possible.

AUTHORS' CONCLUSIONS

As there are no RCTs currently available and the best existing evidence is only from non-randomized studies, there is a need for prospective RCTs to investigate strabismus surgery in the presence of strabismic amblyopia. The optimal timing of when to perform strabismus surgery in children with amblyopia is unknown.

Comparison of botulinum toxin with surgery as primary treatment for infantile esotropia

PURPOSE

To compare bilateral medial rectus muscle injection of botulinum toxin with surgery as primary treatment for infantile esotropia.

METHODS

A single-center, prospective, nonrandomized comparative study was undertaken of botulinum toxin versus surgery in children who presented by age 36 months with esotropia onset before 12 months. Successful outcome was defined as ocular alignment within 10Delta of orthotropia after one surgery or 1 to 3 bilateral botulinum injections.

RESULTS

Of 442 subjects, 322 received botulinum toxin (1 injection, 49%; 2, 41%; 3, 10%); 120 had surgery. Motor success was achieved in 66% of surgery patients, compared with 45% of botulinum patients (p < 0.001). Among subjects with deviation >30Delta, surgery achieved 69% success versus 36% with botulinum toxin (relative risk, 1.95; 95% CI, 1.53-2.49). At deviations < or = 30Delta, there was no difference (surgery, 60%; botulinum toxin, 59%; relative risk, 1.03; 95% CI, 0.78-1.35). There were no statistically significant differences in mean pretreatment deviation (botulinum toxin, 38.8Delta; surgery, 38.2Delta) or mean follow-up (botulinum toxin, 22.6 months; surgery, 20.7). Surgery occurred later than botulinum injection (mean age at treatment, 27.0 vs. 16.7 months; p < 0.001) with greater duration of misalignment (21.0 vs 12.5 months, respectively; p < 0.001), but neither variable influenced outcome in multivariate regression.

CONCLUSIONS

In this large, nonrandomized prospective cohort, surgery was more successful than botulinum toxin in the treatment of large-angle esotropia. Botulinum toxin appeared most effective for esotropia <30Delta to 35Delta, with a success rate comparable with surgery. Botulinum toxin may be an alternative to surgery in children with small- to moderate-angle infantile esotropia.

The effect of amblyopia therapy on ocular alignment

PURPOSE

We sought to describe the change in ocular alignment at 2 years after treatment of amblyopia in children younger than 7 years of age at enrollment.

METHODS

A randomized clinical trial of patching versus atropine for 6 months followed by standard clinical care for 18 months was conducted in 357 children with anisometropic, strabismic, or combined amblyopia (20/40-20/100) whose ages ranged from 3 to younger than 7 years at enrollment. Ocular alignment was evaluated at enrollment and after 2 years of follow-up.

RESULTS

At enrollment when tested at distance fixation, 161 (45%) children were orthotropic, 91 (25%) had a microtropia (1-8 Delta), and 105 (29%) had a heterotropia >8 Delta. Of the 161 patients with no strabismus, similar proportions of patients initially assigned to the patching and atropine groups developed new strabismus by 2 years (18% vs. 16%, P = 0.84). Of these cases of new strabismus, only 2 patients in the patching group and 3 patients in the atropine group developed a deviation that was greater than 8 Delta. Microtropia at enrollment progressed to a deviation greater than 8 Delta with similar frequency in both treatment groups (13% vs. 15%, P = 1.00). Of the 105 patients with strabismus greater than 8 Delta at enrollment, 13% of those in the patching group and 16% of those in the atropine group improved to orthotropia without strabismus surgery. Strabismus surgery was performed in 32 patients during the 2-year study period.

CONCLUSIONS

Patients who had amblyopia treatment with patching or atropine for 6 months followed by standard clinical care were found to have similar rates of deterioration and improvement of ocular alignment. When parents begin amblyopia treatment for children without strabismus, they should be warned of the possibility of development of strabismus, although it is most often a small angle deviation. Strabismus resolved after amblyopia therapy in some cases.

Resolution in partially accomodative esotropia during occlusion treatment for amblyopia

PURPOSE

To evaluate alignment changes in partially accommodative esotropia during occlusion treatment for amblyopia.

METHOD

Changes at the deviation angles of 63 partially accommodative esotropia patients, who had occlusion treatment for amblyopia, were evaluated retrospectively.

RESULTS

Mean deviation angle at the start of therapy without glasses was 45 PD (10-90 PD) and became 27 PD (5-70 PD) after at least 2 months with glasses. During 12 (2-36) months of occlusion period, mean manifest deviation angle with glasses decreased to 11 PD (0-50) (P < 0.001) and amblyopia resolved in 71.5% of the cases. After termination of amblyopia treatment 24 (38%) cases had surgery for the residual deviation but if we had planned surgery before amblyopia treatment, 81% of the patients would have had surgery.

DISCUSSION

Should amblyopia be treated initially or should we operate first in patients with strabismus and amblyopia together? Our research suggests that we should not hurry to operate in high hypermetropic partially accommodative cases, which have amblyopia and a long-term history of strabismus. Initial amblyopia treatment in these cases allows time for resolution of the nonaccomodative component in strabismus and can significantly decrease the necessity for surgery.

Amblyopia characterization, treatment, and prophylaxis

Amblyopia has a 1.6-3.6% prevalence, higher in the medically underserved. It is more complex than simply visual acuity loss and the better eye has sub-clinical deficits. Functional limitations appear more extensive and loss of vision in the better eye of amblyopes more prevalent than previously thought. Amblyopia screening and treatment are efficacious, but cost-effectiveness concerns remain. Refractive correction alone may successfully treat anisometropic amblyopia and it, minimal occlusion, and/or catecholamine treatment can provide initial vision improvement that may improve compliance with subsequent long-duration treatment. Atropine penalization appears as effective as occlusion for moderate amblyopia, with limited-day penalization as effective as full-time. Cytidin-5'-diphosphocholine may hold promise as a medical treatment. Interpretation of much of the amblyopia literature is made difficult by: inaccurate visual acuity measurement at initial visit, lack of adequate refractive correction prior to and during treatment, and lack of long-term follow-up results. Successful treatment can be achieved in at most 63-83% of patients. Treatment outcome is a function of initial visual acuity and type of amblyopia, and a reciprocal product of treatment efficacy, duration, and compliance. Age at treatment onset is not predictive of outcome in many studies but detection under versus over 2-3 years of age may be. Multiple screenings prior to that age, and prompt treatment, reduce prevalence. Would a single early cycloplegic photoscreening be as, or more, successful at detection or prediction than the multiple screenings, and more cost-effective? Penalization and occlusion have minimal incidence of reverse amblyopia and/or side-effects, no significant influence on emmetropization, and no consistent effect on sign or size of post-treatment changes in strabismic deviation. There may be a physiologic basis for better age-indifferent outcome than tapped by current treatment methodologies. Infant refractive correction substantially reduces accommodative esotropia and amblyopia incidence without interference with emmetropization. Compensatory prism, alone or post-operatively, and/or minus lens treatment, and/or wide-field fusional amplitude training, may reduce risk of early onset esotropia. Multivariate screening using continuous-scale measurements may be more effective than traditional single-test dichotomous pass/fail measures. Pigmentation may be one parameter because Caucasians are at higher risk for esotropia than non-whites.