Long-term effect of hypermetropic anisometropia on the visual acuity of treated amblyopic eyes

Prevalence of residual amblyopia in adulthood and its association on educational outcome and quality of life in the Northern Finland Birth Cohort

PURPOSE

The purpose of the current study was to evaluate the prevalence of residual amblyopia in adults in a population screened and treated in childhood. We also wanted to evaluate the association of amblyopia on school success, level of education, and quality of life.

METHODS

This is a follow-up study of 2708 subjects of the Northern Finland Birth Cohort. At the age of 46, the subjects took part in ophthalmic examinations, including the measurement of best-corrected visual acuity (BCVA) and refraction. Residual amblyopia was defined as BCVA 20/30 or less (logMAR ≥0.2) in one or both eyes or a two-line interocular visual acuity difference and absence of any pathological ocular factors. The quality of life was assessed with a 15D questionnaire, and educational outcome, school success, and episodic memory with a CANTAB-PAL (paired associates learning) test were evaluated.

RESULTS

The prevalence of amblyopia in the current adult population aged 46 years was 1.3% (n = 36). At 14 years, the amblyopia subjects had had significant differences in mean spherical equivalent between the amblyopic and fellow eye and strabismus more often than controls. No significant differences were observed in the CANTAB-PAL test or in educational outcome. However, amblyopia subjects had significant difficulties in the 15D questionnaire in terms of vision (54% vs. 34%, p = 0.01).

CONCLUSION

Due to screening and treatment in childhood, the number of adults with residual amblyopia was low. Despite minor visual impairment and discomfort, they cope very well in life in terms of educational outcome and quality of life.

Factors predicting regression of visual acuity following successful treatment of anisometropic amblyopia

Objective

To identify factors associated with visual acuity regression following successful treatment of anisometropic amblyopia.

Design and method

This was a retrospective cohort study. Database records for 100 and 61 children with anisometropic amblyopia who met at least one criterion for successful treatment proposed by the Pediatric Eye Disease Investigator Group (PEDIG) and had at least 1 year of follow-up data available after the criterion was met were analyzed. The study sample was split into two groups, those who regressed within 1 year of successful treatment (no longer met any of the PEDIG criteria for successful treatment) and those who did not. A two-step analysis involving a least absolute shrinkage and selection operator (LASSO) regression and a logistic regression were used to identify predictor variables for increased risk of regression. A broad range of clinical, perceptual, and demographic variables were included in the analyses.

Results

Sixty-eight (42.5%) children regressed within 1 year of successful treatment. Among the 27 predictor variables considered within the statistical modeling process, the three most important for predicting treatment regression were the extent of amblyopic eye visual acuity improvement, age at first hospital visit and sex. Specifically, lower risk of regression was associated with larger amblyopic eye visual acuity improvement with treatment, younger age at initiation of treatment and female sex.

Conclusion

Patients who received treatment at a younger age and responded well to treatment had a lower risk of treatment regression. This pattern of results suggests that early detection of amblyopia and strategies that enhance treatment adherence may reduce the risk of treatment regression. The higher risk of regression in boys than girls that we observed may reflect known sex differences in brain development and /or sex differences in environment within our sample of children from South China.

Functional Deficits and Structural Changes Associated With the Visual Attention Network During Resting State in Adult Strabismic and Anisometropic Amblyopes

Our previous study has shown impaired blood oxygen level-dependent (BOLD)/functional magnetic resonance imaging (fMRI) activation of the visual attention network in strabismic amblyopia (SA). However, there has been no comparison of resting state fMRI activation and functional connectivity (FC) in brain regions of interest (ROIs) along the visual attention network including visual cortex (V1), intraparietal sulcus (IPS), and frontal eye fields (FEFs) during closed eye resting across the SA (n = 20, 13LE), or anisometropic amblyopes (AA) (n = 20, 13LE) groups. Hence, we compared, gray matter volume (GMV), amplitude of low frequency fluctuations (ALFFs), regional homogeneity (ReHo), and FC in the left and right hemisphere ROIs of the visual attention network in SA, AA, and healthy controls (HCs) (n = 21). Correlation analyses of corrected visual acuity (cVA) of amblyopic eye and MRI results were also performed and showed that the LogMAR cVA of the amblyopic eye positively correlated with right zALFF and zReHo FEF of SA and right IPS of AA only. GMV of both left and right hemisphere V1 areas was significantly greater but ALFF was significantly lower for SA compared to AA and HC groups. zALFF and zReHo analyses in the AA and SA groups indicated significantly higher activation than that in the HC group in the right FEF and IPS but lower than that in the HC group in the left FEF, and only the SA group showed lower activation in both V1 areas than the HC group. FC values of the right FEF–left V1, right FEF–right V1, and right FEF–right IPS pathways in the SA and AA groups were also significantly higher than those in the HC group whereas all other FC values were non-significant. Thus, this study indicates that even during resting-state the visual attention network function is impaired in SA and AA participants with only right hemisphere FEF showing significant activation in SA and IPS in AA suggesting that the slower saccade activation times characteristic of amblyopic eyes lead to the dominant eye controlling activation of the visual attention network.

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.

Amblyopia treatment: an evidence‐based approach to maximising treatment outcome

The basis of treatment for amblyopia (poor vision due to abnormal visual experience early in life) for 250 years has been patching of the unaffected eye for extended times to ensure a period of use of the affected eye. Over the last decade randomised controlled treatment trials have provided some evidence on how to tailor amblyopia therapy more precisely to achieve the best visual outcome with the least negative impact on the patient and the family. This review highlights the expansion of knowledge regarding treatment for amblyopia and aims to provide optometrists with a summary of research evidence to enable them to better treat amblyopia. Treatment for amblyopia is effective, as it reduces overall prevalence and severity of visual loss in this population. Correction of refractive error alone significantly improves visual acuity, sometimes to the point where further amblyopia treatment is not required. Atropine penalisation and patch occlusion are effective in treating amblyopia. Lesser amounts of occlusion or penalisation have been found to be just as effective as greater amounts. Recent evidence has highlighted that occlusion or penalisation in amblyopia treatment can create negative changes in behaviour in children and impact on family life. These complications should be considered when prescribing treatment because they can negatively affect compliance. Studies investigating the maximum age at which treatment of amblyopia can still be effective and the importance of near activities during occlusion are ongoing.

Amblyopia: prevalence, natural history, functional effects and treatment

Amblyopia, defined as poor vision due to abnormal visual experience early in life, affects approximately three per cent of the population and carries a projected lifetime risk of visual loss of at least 1.2 per cent. The presence of amblyopia or its risk factors, mainly strabismus or refractive error, have been primary conditions targeted in childhood vision screenings. Continued support for such screenings requires evidence-based understanding of the prevalence and natural history of amblyopia and its predisposing conditions, and proof that treatment is effective in the long term with minimal negative impact on the patient and family. This review summarises recent research relevant to the clinical understanding of amblyopia, including prevalence data, risk factors, the functional impact of amblyopia and optimum treatment regimes and their justification from a vision and life skills perspective. Collectively, these studies indicate that treatment for amblyopia is effective in reducing the overall prevalence and severity of visual loss from amblyopia. Correction of refractive error alone has been shown to significantly reduce amblyopia and less frequent occlusion can be just as effective as more extensive occlusion. Occlusion or penalisation in amblyopia treatment can create negative changes in behaviour in children and impact on family life, and these factors should be considered in prescribing treatment, particularly because of their influence on compliance. Ongoing treatment trials are being undertaken to determine both the maximum age at which treatment of amblyopia can still be effective and the importance of near activities during occlusion. This review highlights the expansion of current knowledge regarding amblyopia and its treatment to help clinicians provide the best level of care for their amblyopic patients that current knowledge allows.

Factors predicting recurrence in successfully treated cases of anisometropic amblyopia

Context:

Recurrence after successful treatment of amblyopia is known and understanding the risk factors could help effective management.

Aim:

To measure incidence of recurrence in successfully treated cases of anisometropic amblyopia and evaluate factors predicting it.

Settings and Design:

Cohort Study at a tertiary level institution.

Materials and Methods:

Successfully treated anisometropic amblyopes aged 4−12 years were followed up for 1 year after stopping therapy. Best corrected visual acuity (BCVA), refractive error, stereoacuity and contrast sensitivity were evaluated at baseline and follow-up.

Statistical Analysis:

Intergroup analysis with appropriate tests: Chi-square test, Fisher's exact test, Wilcoxon rank sum test and paired t-test.

Results:

One hundred and two patients with mean age at diagnosis 7.06 ± 1.81 years were followed-up for a mean duration of 1.0 ± 0.2 years. The mean pre-treatment BCVA (LogMAR score) at diagnosis was 0.73 ± 0.36 units which improved to 0.20 ± 0.00 with treatment and after 1 year of stopping treatment was 0.22 ± 0.07. Thirteen (12.74%) patients showed amblyopia recurrence during follow-up. Risk of recurrence was higher with older age of onset of treatment (6.64 ± 1.77 years without recurrence v/s 8.53 ± 1.39 years with recurrence, P = 0.0014). Greater extent of improvement of VA (P = 0.048) and final VA at stopping occlusion (P = 0.03) were associated with higher recurrence. Binocularity status or stereoacuity changes were not associated with risk of recurrence.

Conclusions:

Significant numbers of children suffer recurrence of amblyopia after stopping therapy. Older age, better BCVA after stopping therapy and greater magnitude of improvement in BCVA are important risk factors for recurrence. Careful follow-up is essential for early detection and management of recurrence.

Termination of amblyopia treatment: when to stop follow-up visits and risk factors for recurrence

BACKGROUND

This study estimated when it is safe to stop follow-up visits after cessation of amblyopia treatment and to identify factors associated with deterioration of visual acuity.

METHODS

Study patients included 282 patients aged 7 to 13 years who were monitored for deterioration after cessation of amblyopia treatment (median follow-up: 3.9 years).

RESULTS

Six (2.1%) patients lost 2 or more logarithm of the minimum angle of resolution levels of visual acuity and 77 (27.3%) patients lost 1 or more Snellen lines of visual acuity. Good compliance with re-treatment stopped further deterioration and lost visual acuity was regained (average follow-up after re-treatment: 3.3 years). Life table analysis indicated that 95% of the cases that deteriorated occurred within 24 months after cessation of treatment. Multivariable analysis corrected for duration of treatment uncovered factors independently associated with deterioration.

CONCLUSION

A clinically important risk of deterioration of visual acuity was found during the first 2 years after cessation of amblyopia treatment. Follow-up time longer than 2 years is recommended in the presence of a developing risk factor such as increasing anisometropia. With prompt re-treatment and good compliance, deterioration can be stopped and visual acuity can be restored.

Factors associated with recurrence of amblyopia on cessation of patching

PURPOSE

In a prospective observational study, we previously reported that weaning (tapering or gradually reducing) treatment in children treated with 6 to 8 hours of daily patching for amblyopia resulted in a 4-fold reduction in odds of recurrence. We now report the association of additional factors with recurrence or regression of amblyopia in this same cohort.

DESIGN

Prospective, nonrandomized, observational study.

PARTICIPANTS

Sixty-nine children aged <8 years with successfully treated anisometropic or strabismic amblyopia (improved > or =3 logarithm of the minimum angle of resolution [logMAR] lines).

METHODS

Patients were enrolled at the time they stopped patching for amblyopia. Patients were classified according to whether patching was stopped abruptly or weaned before cessation. They were followed off treatment for 52 weeks to assess recurrence of amblyopia.

MAIN OUTCOME MEASURE

Recurrence of amblyopia defined as a > or =2-logMAR level reduction of visual acuity from enrollment (cessation of patching) confirmed by a second examination. Recurrence was also considered to have occurred if treatment was restarted with a > or =2-logMAR level reduction of visual acuity, even if it was not confirmed by a second examination.

RESULTS

The risk of recurrence was higher with better visual acuity at the time of cessation of treatment (adjusted risk ratio [RR], 0.68 per line of worse visual acuity; 95% confidence interval [CI], 0.51-0.90), a greater number of lines improved during the previous treatment (adjusted RR, 1.5 per line increase; 95% CI, 1.1-2.0), and a history of recurrence (adjusted RR, 2.7; 95% CI, 1.5-4.9). Orthotropia or excellent stereoacuity at the time of patching cessation did not appear to have a protective effect on the risk of recurrence.

CONCLUSIONS

The higher risk of recurrence in the most successfully treated children with amblyopia and absence of protection from orthotropia and excellent random dot stereoacuity suggests that careful and prolonged follow-up is needed for all children who have been previously treated for amblyopia.

Factors affecting the stability of visual function following cessation of occlusion therapy for amblyopia

AIM

To identify factors that predict which children with amblyopia are at greatest risk of regression of visual acuity (VA) following the cessation of occlusion therapy.

METHOD

A retrospective analysis was performed of 182 children (mean age at cessation of treatment; 5.9+/-1.6 years) who had undergone occlusion therapy for unilateral amblyopia, and had been followed up at least once within 15 months of cessation. Statistical analysis was used to identify whether change in VA following treatment cessation had any association with various factors, including the child's age, type of amblyopia, degree of anisometropia, initial severity of amblyopia, binocular vision status, length and dose of occlusion therapy, and VA response to treatment.

RESULTS

At 1 year, follow-up from treatment cessation, children with "mixed" amblyopia (both anisometropia and strabismus) demonstrated significantly (p=0.03) greater deterioration in VA (0.11+/-0.11 log units) than children with only anisometropia (0.02+/-0.08 log units) or only strabismus (0.05+/-0.10 log units). However, none of the other factors investigated were found to be significant predictors.

CONCLUSION

This study supports previous research that it is possible to identify those children most at risk of deterioration in VA following cessation of occlusion therapy. The presence of mixed amblyopia was the only risk factor identified in this study. Management of amblyopia should take this into account, with a more intensive follow-up recommended for those with both anisometropia and strabismus (mixed) amblyopia.

Successful treatment of anisometropic amblyopia with spectacles alone

BACKGROUND

The efficacy of treating anisometropic amblyopia with occlusion therapy is well known. However, this form of treatment can be associated with risks. Spectacle correction alone may be a successful and underutilized form of treatment.

METHODS

The records of 28 patients treated successfully for anisometropic amblyopia with glasses alone were reviewed. Age, initial visual acuity and stereoacuity, and nature of anisometropia were analyzed to assess associations with time required for resolution, final visual acuity, and stereoacuity. Incidence of amblyopia recurrence and results of subsequent treatment, including patching, were also studied.

RESULTS

Mean time to amblyopia resolution (interocular acuity difference <or=1 line) was 5.8 months (range 2 to 15 months). Worse best corrected initial visual acuity was associated with longer time to resolution (Spearman's rho = 0.37, P = 0.05), while age, initial stereoacuity, amount, and type of anisometropia were not (P = 0.43, 0.68, 0.26, 0.47, respectively). None of the astigmatic or myopic patients achieved visual acuity of 20/20 in the amblyopic eye, while seven (39%) of the hyperopic patients did. This difference was significant (P = 0.03). Better initial stereoacuity predicted good final stereoacuity (P = 0.01). Only four (14%) patients developed amblyopia recurrence over an average follow-up period of 1.7 years. All were successfully treated with updated spectacles or patching.

CONCLUSIONS

Treatment of anisometropic amblyopia with spectacles alone can be a successful option. Patients treated with spectacles alone may experience a lower amblyopia recurrence rate than those treated with occlusion therapy.

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.

The relationship between anisometropia, patient age, and the development of amblyopia

PURPOSE

Anisometropia is a common cause of amblyopia. The relationship between anisometropia, patient age, and the development of amblyopia is unknown. Photoscreening identifies children with anisometropia in a manner that is not biased by visual acuity and allows a unique opportunity to evaluate how patient age influences the prevalence and depth of anisometropic amblyopia.

METHODS

A statewide preschool photoscreening program screened 120,000 children and identified 792 with anisometropia greater than 1.0 diopter. Age was correlated with visual acuity and amblyopia depth. Data were compared with those from 562 strabismic children similarly identified.

RESULTS

Only 14% (6/44) of anisometropic children aged 1 year or less had amblyopia. Prevalence was 40% (32/80) for 2-year-olds, 65% (119/182) for 3-year-olds, and peaked at 76% (age 5). Amblyopia depth also increased with age. Moderate amblyopia prevalence was 2% (ages 0 to 1), 17% (age 2), and rose steadily to 45% (ages 6 to 7). Severe amblyopia was rare prior to age 4, 9% at age 4, 14% at age 5, and 9% at ages 6 to 7. In contrast, children with strabismus had a stable prevalence of amblyopia (30% at ages 0 to 2, 42% at ages 3 to 4, 44% at ages 5 to 7).

CONCLUSIONS

Younger children with anisometropic refractive error have a lower prevalence and depth of amblyopia than do older children. By age 4, when most children undergo traditional screening, amblyopia has usually already developed. New vision screening technologies that allow early detection of anisometropia provide ophthalmologists an opportunity to intervene early, perhaps retarding, or even preventing, the development of amblyopia.

Long-term follow-up of occlusion therapy in amblyopia

OBJECTIVE

To determine whether the results of occlusion therapy for amblyopia are maintained into adulthood.

DESIGN

Prospective, observational case series.

PARTICIPANTS

Fifty-four patients, who were successfully treated in childhood for unilateral amblyopia by occlusion, were followed up to the age of 9 years, were evaluated in 1984 for long-term results 6.4 years on average after cessation of treatment, and accepted our invitation for reevaluation in 1999.

METHODS

All patients were given a complete eye examination. The visual acuity (VA) was measured.

RESULTS

The average period of follow-up was 21.5 years (range, 17.2-25.1 years). The mean age at the most recent examination was 29.0 +/- 2.1 years (range, 25.1-34). At this examination, a best-corrected visual acuity (BCVA) of 20/40 or better was achieved by 72.3% of the patients. The mean BCVA was 20/35 (20/25-20/70) at the end of occlusion therapy, 20/45 (20/20-20/300) in 1984, and 20/34 (20/15-20/100) at the present examination. Relative to the results at the end of therapy, BCVA at the present examination was maintained or improved in 66.7% of the patients. Relative to 1984, the BCVA in 1999 was maintained or improved in 87% of the patients.

MAIN OUTCOME MEASURE

Visual acuity.

CONCLUSION

Comparative evaluation of BCVA at a long-term follow-up examination, performed 21.5 years on average after cessation of occlusion therapy, showed that VA was maintained or improved in two thirds of patients who had been successfully treated by occlusion for unilateral amblyopia in childhood.

The detection, prevention, and rehabilitation of amblyopia

Some of the past year's important papers on amblyopia are reviewed. Preschool screening for amblyopia is still controversial in regard to its effectiveness, the best age, and the most cost-effective method. In Sweden, where screening for amblyopia is well established, the prevalence of deep and moderate amblyopia has been markedly reduced. Several studies in the past year underscored the importance of anisometropia as a risk factor for amblyopia. Clear evidence for the importance of early treatment of unilateral cataracts in the first 8 weeks of life has been shown. Cytidine-5'-diphosphocholine administration has been shown to positively influence amblyopia and represents, in addition to levodopa, another promising pharmacologic treatment.