Stereopsis and long-term stability of alignment in esotropia

Trends and patterns in pediatric ophthalmology and strabismus surgeries: a decade review from a leading Portuguese university hospital

PURPOSE

Strabismus and Pediatrics Ophthalmology surgeries are pivotal in addressing early-onset visual disorders. An 11-year retrospective study at a tertiary hospital center aimed to elucidate evolving surgical trends, focusing on esotropia cases.

METHODS

The surgical records from January 2009 to January 2020 were analyzed according to the baseline diagnosis. Esotropia cases were evaluated based on the patients' deviation types, surgical techniques, and pre-operative characteristics. A total of 2050 surgeries were performed over the study period.

RESULTS

Strabismus surgery accounts for 70% of the department's surgical activity. A trend toward a decrease in esotropia surgeries and a proportional increase in exotropia surgeries was noticeable. Esotropia cases, with a median surgical age of 6 years (p25-p75, 4-10) and uniform gender distribution (females, 54.8%), predominantly involved high angular deviations. Posterior fixation sutures emerged as the preferred surgical technique for esotropia.

CONCLUSION

The study's insights, while aligning with prior European research, introduce new dimensions to the understanding of strabismus surgeries, emphasizing the significance of early interventions, evolving surgical preferences, and the challenges posed by severe deviations.

Characteristics and risk factors for spontaneous and postoperative consecutive exotropia in children with esotropia

Background

To investigate the risk factors for the development of consecutive exotropia (CXT) by comparing patients with spontaneous or postoperative CXT during follow-up with another group of patients who had no deviation or less than 10 prism dioptre (PD) esotropia.

Methods

In this retrospective cohort study, 6 patients with spontaneous CXT (group A), 13 patients with postoperative CXT (group B), and 39 patients with no exotropia (group C) were enrolled. Probable risk factors for CXT were evaluated among the groups. Kruskal-Wallis H test was used to determine if any significant differences were present among the groups. Fisher's exact test or Mann-Whitney U test was used for univariate analyses to compare differences between case groups or between case and control groups. The Bonferroni method was used to conduct multiple comparisons.

Results

The follow-up period of spontaneous CXT patients was significantly longer than that of postoperative CXT and nonconsecutive exotropia patients (p = 0.035 and p < 0.001, respectively). The interval between alignment and CXT onset in spontaneous CXT patients was slightly longer than that in postoperative CXT patients, but not significantly difference (6.50 vs. 5.00 years, p = 0.072). Vertical deviation was associated with a high risk of postoperative CXT (p = 0.001). Most [38 (97.44%)] nonconsecutive exotropia patients had fusion; conversely, the absence of fusion function (p < 0.001) as well as stereoacuity (p = 0.029) were associated with a high risk of CXT.

Conclusion

Vertical deviation and poor binocular function are strongly associated with a high risk of CXT. Children with spontaneous CXT are highly recommended to be followed-up long-term, while they maintain long-term ocular alignment before developing consecutive exotropia from comitant esotropia (CE).

Amblyopia and the whole child

Amblyopia is a disorder of neurodevelopment that occurs when there is discordant binocular visual experience during the first years of life. While treatments are effective in improving visual acuity, there are significant individual differences in response to treatment that cannot be attributed solely to difference in adherence. In this considerable variability in response to treatment, we argue that treatment outcomes might be optimized by utilizing deep phenotyping of amblyopic deficits to guide alternative treatment choices. In addition, an understanding of the broader knock-on effects of amblyopia on developing visually-guided skills, self-perception, and quality of life will facilitate a whole person healthcare approach to amblyopia.

Timing of surgery in essential infantile esotropia - What more do we know since the turn of the century?

This review summarizes the results and interpretations of studies pertaining to the long-standing debate regarding the timing of surgery in infantile esotropia, more recently referred to as essential infantile esotropia. A systematic search of studies from the year 2000 onward pertaining to the timing of surgery in infantile esotropia as listed in PubMed, Google Scholar, and the Cochrane database was performed. Appropriate cross-references from the articles were also included. Data collected included demographics, presentation, time of surgery, complications, and outcomes. Very early surgery, that is, within 6 months of the onset of infantile esotropia, offers significant advantages in terms of the quality of stereopsis and binocular vision as well as promoting the development of cortical visual processing, thereby benefiting cortical development in human infants. However, the postoperative alignment was not found to be significantly different in the very early, early, or late surgery groups. The reduction in the incidence of manifest dissociated vertical deviation postoperatively in the very early surgery group also showed measurable benefits. The results of this recent literature review demonstrated that very early surgery, within 6 months of misalignment, showed demonstrable benefits in essential infantile esotropia.

Recent Advances in Screening and Treatment for Amblyopia

Amblyopia is the most common cause of monocular visual impairment in children, with a prevalence of 2-3%. Not only is visual acuity reduced in one eye but binocular vision is affected, fellow eye deficits may be present, eye-hand coordination and reading can be affected, and self-perception may be diminished. New technologies for preschool vision screening hold promise for accessible, early, and accurate detection of amblyopia. Together with recent advances in our theoretical understanding of amblyopia and technological advances in amblyopia treatment, we anticipate improved visual outcomes for children affected by this very common eye condition. This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.

Management of patients with small-angle esotropia and subnormal stereopsis using Fresnel prism

PURPOSE

Monofixation syndrome (MFS) is a specific subnormal binocular vision status, either with or without a small deviation. Patients with MFS have a tendency to maintain stable ocular alignment. Correction of refractive errors and occlusion are considered as treatment option for amblyopia, and the status of MFS could be changed with long-term follow-up. The purpose of this study is to evaluate whether a Fresnel prism affected the visual acuity, angle of deviation, and sensory status in small-angle esotropia with subnormal stereopsis presenting with MFS features.

METHODS

Patients with small-angle esotropia within 8 prism diopters (PD) on the simultaneous prism and cover test from 2010 to 2019 were reviewed. Patients with subnormal stereopsis defined as more than 100 s of arc (arcsec) and with the central suppression with peripheral fusion were only included. A Fresnel prism was applied to the dominant eye, and the minimum follow-up period after Fresnel prism treatment was 24 months. We assessed patient clinical characteristics, course and response to therapy including visual acuity, angle of deviation, and stereopsis.

RESULTS

Twenty patients with a mean age of 5.5 ± 1.4 years were included. The mean duration of Fresnel prism treatment was 15.3 ± 10.3 months. After 50.7 ± 17.2 months of follow-up, VA of the non-dominant eye was changed from 0.26 ± 0.20 logMAR to 0.07 ± 0.17 logMAR (P < .001). The initial stereoacuities were 3.54 ± 0.27 log arcsec, ranged from 6000 to 400 arcsec. After the treatment with Fresnel prism, the final stereoacuities were 3.09 ± 0.58 log arcsec, ranged from 6000 to 100 arcsec (P = .001); nine patients (45%) improved stereoacuity more than two octaves. No changes in the angle of deviation or a change of fixation were observed.

CONCLUSIONS

After use of Fresnel prism, there was some improvement in visual acuity and stereopsis in patients with MFS features. Following occlusion and refractive correction, management using Fresnel prism could be attempted in small-angle esotropic patients with amblyopia or subnormal stereopsis.

Amblyopia

Amblyopia is a neurodevelopmental abnormality that results in physiological alterations in the visual pathways and impaired vision in one eye, less commonly in both. It reflects a broad range of neural, perceptual, oculomotor, and clinical abnormalities that can occur when normal visual development is disrupted early in life. Aside from refractive error, amblyopia is the most common cause of vision loss in infants and young children. It causes a constellation of perceptual deficits in the vision of the amblyopic eye, including a loss of visual acuity, position acuity, and contrast sensitivity, particularly at high spatial frequencies, as well as increased internal noise and prolonged manual and saccadic reaction times. There are also perceptual deficits in the strong eye, such as certain types of motion perception, reflecting altered neural responses and functional connectivity in visual cortex (Ho et al., 2005). Treatment in young children consists of correction of any refractive error and patching of the strong eye. Compliance with patching is challenging and a substantial proportion of amblyopic children fail to achieve normal acuity or stereopsis even after extended periods of treatment. There are a number of promising experimental treatments that may improve compliance and outcomes, such as the playing of action video games with the strong eye patched. Although there may be a sensitive period for optimal effects of treatment, there is evidence that amblyopic adults may still show some benefit of treatment. However, there is as yet no consensus on the treatment of adults with amblyopia.

Rethinking amblyopia 2020

Recent work has transformed our ideas about the neural mechanisms, behavioral consequences and effective therapies for amblyopia. Since the 1700's, the clinical treatment for amblyopia has consisted of patching or penalizing the strong eye, to force the "lazy" amblyopic eye, to work. This treatment has generally been limited to infants and young children during a sensitive period of development. Over the last 20 years we have learned much about the nature and neural mechanisms underlying the loss of spatial and binocular vision in amblyopia, and that a degree of neural plasticity persists well beyond the sensitive period. Importantly, the last decade has seen a resurgence of research into new approaches to the treatment of amblyopia both in children and adults, which emphasize that monocular therapies may not be the most effective for the fundamentally binocular disorder that is amblyopia. These approaches include perceptual learning, video game play and binocular methods aimed at reducing inhibition of the amblyopic eye by the strong fellow eye, and enhancing binocular fusion and stereopsis. This review focuses on the what we've learned over the past 20 years or so, and will highlight both the successes of these new treatment approaches in labs around the world, and their failures in clinical trials. Reconciling these results raises important new questions that may help to focus future directions.

Combined passive and active treatment in strabismic amblyopia with accommodative component

BACKGROUND

Treatment of amblyopia in esotropic subjects with accommodative component currently consists of optical correction and subsequent occlusion, or penalisation, of the dominant eye. This treatment obtains a good outcome in visual acuity but poor outcomes in binocular vision. An intervention protocol that could improve the outcome of conventional treatment is presented.

METHODS

A retrospective study in subjects with amblyopia associated with both fully accommodative and partially accommodative esotropia is presented. Subjects were refracted under cycloplegia and treated with occlusion (passive therapy). Subjects who did not achieve orthotropia through optical correction (partially accommodative esotropia) performed an active therapy (full-time prismatic correction and subsequent fusional vergence therapy or surgery in larger angles > 12 prism dioptres). After treatment, the subjects were examined by a masked optometrist in an external ophthalmology clinic.

RESULTS

Twenty-six subjects (12 males and 14 females) aged from six to 13 years (median 8.50; interquartile range [IQR] 3) were included. Median age of detection was three years (IQR 1). All the subjects were hyperopic. In the baseline, median best-corrected visual acuity of the amblyopic eye was 0.40 logMAR (IQR 0.30) and 0.00 logMAR (IQR 0.01) in the dominant eye. After the treatment, the median best-corrected visual acuity in the amblyopic eye was 0.06 logMAR (IQR 0.08). These differences were statistically significant (p < 0.001). All subjects acquired stereoacuity equal or better than 800'' with the Randot Preschool Stereoacuity Test.

CONCLUSIONS

The proposed treatment highlights the management of amblyopia in esotropic subjects with accommodative component. This intervention protocol could help to determine if the treatment has to be passive (in fully accommodative esotropia) or a combination of passive and active therapies (in partially accommodative esotropia).

A dichoptic feedback-based oculomotor training method to manipulate interocular alignment

Strabismus is a prevalent impairment of binocular alignment that is associated with a spectrum of perceptual deficits and social disadvantages. Current treatments for strabismus involve ocular alignment through surgical or optical methods and may include vision therapy exercises. In the present study, we explore the potential of real-time dichoptic visual feedback that may be used to quantify and manipulate interocular alignment. A gaze-contingent ring was presented independently to each eye of 11 normally-sighted observers as they fixated a target dot presented only to their dominant eye. Their task was to center the rings within 2° of the target for at least 1 s, with feedback provided by the sizes of the rings. By offsetting the ring in the non-dominant eye temporally or nasally, this task required convergence or divergence, respectively, of the non-dominant eye. Eight of 11 observers attained 5° asymmetric convergence and 3 of 11 attained 3° asymmetric divergence. The results suggest that real-time gaze-contingent feedback may be used to quantify and transiently simulate strabismus and holds promise as a method to augment existing therapies for oculomotor alignment disorders.

Can Clinical Measures of Postoperative Binocular Function Predict the Long-Term Stability of Postoperative Alignment in Intermittent Exotropia?

Purpose

To evaluate whether clinical measures of postoperative binocular functions could predict the long-term stability of postoperative ocular alignment in children with intermittent exotropia.

Methods

A retrospective study was performed in thirty-nine children (median: 7 years) who have been surgically treated from intermittent exotropia without overcorrection (less than 10 prism diopters [pd] of exodeviation at 1 month postoperatively). Angles of deviation and binocular functions were measured preoperatively and at 1 month, 6 months, and the final follow-up visit (≥24 months) postoperatively. We examined the relationships between postoperative drift (change of ocular alignment) and binocular functions (sensory fusion, fusional convergence amplitude, and stereoacuity).

Results

The surgical success rate (esophoria/tropia ≤5 pd to exophoria/tropia ≤10 pd) dropped to 76.9% at 6 months after surgery and to 53.8% at individuals' last visit (mean: 37 months). The mean exodrift was 7.7 ± 9.2 pd from the postoperative month 1 to the final visit (p < 0.001) on distance fixation. Distance stereoacuity, central fusion, and fusional convergence amplitude significantly improved following surgery (p < 0.05). However, no significant correlation was found between their binocular functions measured at the beginning of each follow-up period and the postoperative drift (all p > 0.13).

Conclusion

Our findings suggest that the clinical measures of sensory fusion, fusional convergence amplitude, and stereoacuity cannot serve as a robust predictor for the long-term stability of postoperative ocular alignment in patients who underwent successful surgery without overcorrection at 1 month postoperatively.

Comparison of a New, Filter-Free Stereopsis Test (BEST) With the Randot Stereotest in a Pediatric Cohort

PURPOSE

To evaluate the Bernell Evaluation of Stereopsis Test (BEST) (Bernell Corporation, Mishawaka, IN), a new lenticular technology and filter-free test to measure stereopsis in children, and compare it to the Randot Stereotest (Randot) (Stereo Optical, Inc., Chicago, IL).

METHODS

This was a retrospective review of the medical records of children examined at the Center for Pediatric Ophthalmology at Hadassah-Hebrew University Medical Center from July to November 2018. All children were evaluated with the Randot and BEST in a random order.

RESULTS

The study included 100 children (53% female, 64% orthophoric) with a mean age of 8.52 ± 3.18 years (range: 3.3 to 17.8 years) and mean best corrected visual acuity of 0.178 ± 0.16 logMAR (range: 0 to 0.7 logMAR). The mean BEST stereoacuity was 1.772 ± 0.27 log seconds of arc (arcsec), whereas the mean Randot stereo-acuity was 1.778 ± 0.39 log arcsec (P = .835). The Bland- Altman analysis revealed an overall bias of 0.0073 log arcsec (95% confidence interval: 0.04219 to 0.05679 log arcsec), with limits of agreement of -0.4816 to 0.4962 log arcsec (0.3299 to 3.1347 arcsec). A significant proportional bias was noted because the difference between the tests was significantly larger in higher log arcsec values (t = 5.566, P < .001). Age, gender, strabismus, and visual acuity did not affect the differences between the stereoacuity tests (P > .05). Both tests were influenced by strabismus but not monocular amblyopia.

CONCLUSIONS

BEST stereoacuity measurements were comparable to those of the Randot, with no significant difference in crude values, minimal bias, and narrow limits of agreement. A larger, clinically insignificant variability between tests was noted with lower stereoacuity values, because children achieved better scores with the BEST. The BEST may be a valuable tool in the arsenal of the ophthalmologist. [J Pediatr Ophthalmol Strabismus. 2020;57(2):129-135.].

Lateral rectus sag and recurrent esotropia in children

PURPOSE

To describe the clinical and intraoperative findings of an anatomic abnormality in children that resembles sagging eye syndrome documented in older adults and that led to recurrent esotropia after surgery.

METHODS

We reviewed records of 4 patients with substantial recurrent esotropia after bilateral medial rectus recession who required subsequent surgery combining lateral rectus resection with correction of the anatomic abnormality affecting the lateral rectus path. Binocular alignment was sequentially analyzed.

RESULTS

Three young patients (2-3 years of age) presented with acquired esotropia but minimal cycloplegic refractive error. The fourth patient (14 years of age) initially had moderate hyperopia and partially accommodative esotropia, but subsequently developed marked bilateral overelevation in adduction. In all patients, esotropia recurred within 5^Δ of preoperative deviation after bilateral medial rectus recession. Surgical exposure demonstrated that bilateral lateral rectus paths were inferiorly displaced more than one-half tendon width from their normal paths near the globe's equator, despite normal scleral insertions. Equatorial myopexy and lateral rectus resection resulted in stable esotropia correction.

CONCLUSIONS

Lateral rectus sag in children creates a type of acquired esotropia and overelevation in adduction poorly responsive to standard surgery but correctable with lateral rectus resection and equatorial myopexy that normalizes the lateral rectus path through permanent scleral fixation.

Improved Binocular Outcomes Following Binocular Treatment for Childhood Amblyopia

Purpose

Childhood amblyopia can be treated with binocular games or movies that rebalance contrast between the eyes, which is thought to reduce depth of interocular suppression so the child can experience binocular vision. While visual acuity gains have been reported following binocular treatment, studies rarely report gains in binocular outcomes (i.e., stereoacuity, suppression) in amblyopic children. Here, we evaluated binocular outcomes in children who had received binocular treatment for childhood amblyopia.

Methods

Data for amblyopic children enrolled in two ongoing studies were pooled. The sample included 41 amblyopic children (6 strabismic, 21 anisometropic, 14 combined; age 4–10 years; ≤4 prism diopters [PD]) who received binocular treatment (20 game, 21 movies; prescribed 9–10 hours treatment). Amblyopic eye visual acuity and binocular outcomes (Randot Preschool Stereoacuity, extent of suppression, and depth of suppression) were assessed at baseline and at 2 weeks.

Results

Mean amblyopic eye visual acuity (P < 0.001) and mean stereoacuity improved (P = 0.045), and mean extent (P = 0.005) and depth of suppression (P = 0.003) were reduced from baseline at the 2-week visit (87% game adherence, 100% movie adherence). Depth of suppression was reduced more in children aged <8 years than in those aged ≥8 years (P = 0.004). Worse baseline depth of suppression was correlated with a larger depth of suppression reduction at 2 weeks (P = 0.001).

Conclusions

After 2 weeks, binocular treatment in amblyopic children improved visual acuity and binocular outcomes, reducing the extent and depth of suppression and improving stereoacuity. Binocular treatments that rebalance contrast to overcome suppression are a promising additional option for treating amblyopia.

An action video game for the treatment of amblyopia in children: A feasibility study

The gold-standard treatment for childhood amblyopia remains patching or penalizing the fellow eye, resulting in an average of about a one line (0.1 logMAR) improvement in visual acuity following ≈120 h of patching in children 3-8 years old. However, compliance with patching and other treatment options is often poor. In contrast, fast-paced action video games can be highly engaging, and have been shown to yield broad-based improvements in vision and attention in adult amblyopia. Here, we pilot-tested a custom-made action video game to treat children with amblyopia. Twenty-one (n = 21) children (mean age 9.95 ± 3.14 [se]) with unilateral amblyopia (n = 12 anisometropic and n = 9 strabismic) completed 20 h of game play either monocularly, with the fellow eye patched (n = 11), or dichoptically, with reduced contrast to the fellow eye (n = 10). Participants were assessed for visual acuity (VA), stereo acuity and reading speed at baseline, and following 10 and 20 h of play. Additional exploratory analyses examined improvements after 6-10 weeks of completion of training (follow-up). Following 20 h of training, VA improved, on average, by 0.14 logMAR (≈38%) for the dichoptic group and by 0.06 logMAR (≈15%) for the monocular group. Similarly, stereoacuity improved by 0.07 log arcsec (≈17%) following dichoptic training, and by 0.06 log arcsec (≈15%) following monocular training. Across both treatment groups, 7 of the 12 individuals with anisometropic amblyopia showed improvement in stereoacuity, whereas only 1 of the 9 strabismic individuals improved. Most improvements were largely retained at follow-up. Our feasibility study therefore suggests that the action video game approach may be used as an effective adjunct treatment for amblyopia in children, achieving results similar to those of the gold-standard treatment in shorter duration.

Accommodative esotropia: the state of the art

PURPOSE

To review the state of the art of Accommodative Esotropia (AE) through careful study of what has been reported up to the point in literature.

METHODS

A literature search was done on PubMed using key words including "Accommodative esotropia", "Infantile esotropia", "Strabismus" and "Accommodation". We systematically reviewed and critically appraised what has been written about AE and we tried to analyze that according to the current management of AE.

RESULTS

Accommodative Esotropia (AE) is a form of strabismus characterized by convergent misalignment of the visual axes that can be associated with hyperopia and abnormal fusional divergence. Also abnormal accommodative convergence/accommodation ratio could be found. In lots of cases, AE initially presents as an intermittent esodeviation at age 1.5 to 4 years. The prevalence of AE has been estimated near 1-2% in the United States. The only treatment with an optical correction usually is successful in re-establishing alignment, but surgical correction is necessary in approximately 30% of cases.

Binocular iPad Game vs Patching for Treatment of Amblyopia in Children: A Randomized Clinical Trial

Importance

Fellow eye patching has long been the standard treatment for amblyopia, but it does not always restore 20/20 vision or teach the eyes to work together. Amblyopia can be treated with binocular games that rebalance contrast between the eyes so that a child may overcome suppression. However, it is unclear whether binocular treatment is comparable to patching in treating amblyopia.

Objectives

To assess the effectiveness of a binocular iPad (Apple Inc) adventure game as amblyopia treatment and compare this binocular treatment with patching, the current standard of care.

Design, Setting, and Participants

This investigation was a randomized clinical trial with a crossover design at a nonprofit eye research institute. Between February 20, 2015, and January 4, 2016, a total of 28 patients were enrolled in the study, with 14 randomized to binocular game treatment and 14 to patching treatment.

Interventions

Binocular game and patching as amblyopia treatments.

Main Outcomes and Measures

The primary outcome was change in amblyopic eye best-corrected visual acuity (BCVA) at the 2-week visit. Secondary outcomes were change in stereoacuity and suppression at the 2-week visit and change in BCVA at the 4-week visit.

Results

Among 28 children, the mean (SD) age at baseline was 6.7 (1.4) years (age range, 4.6-9.5 years), and 7 (25%) were female. At baseline, the mean (SD) amblyopic eye BCVA was 0.48 (0.14) logMAR (approximately 20/63; range, 0.3-0.8 logMAR [20/40 to 20/125]), with 14 children randomized to the binocular game and 14 to patching for 2 weeks. At the 2-week visit, improvement in amblyopic eye BCVA was greater with the binocular game compared with patching, with a mean (SD) improvement of 0.15 (0.08) logMAR (mean [SD], 1.5 [0.8] lines) vs 0.07 (0.08) logMAR (mean [SD], 0.7 [0.8] line; P = .02) after 2 weeks of treatment. These improvements from baseline were significant for the binocular game (mean [SD] improvement, 1.5 [0.8] lines; P < .001) and for patching (mean [SD] improvement, 0.7 [0.8] line; P = .006). Depth of suppression improved from baseline at the 2-week visit for the binocular game (mean [SD], 4.82 [2.82] vs 3.24 [2.87]; P = .03) and for patching (mean [SD], 4.77 [3.10] vs 2.57 [1.67]; P = .004). Patching children crossed over to binocular game treatment, and all 28 children played the game for another 2 weeks. At the 4-week visit, no group difference was found in BCVA change, with children who crossed over to the binocular games catching up with children treated with binocular games, for a mean (SD) improvement of 0.17 (0.10) logMAR (mean [SD], 1.7 [1.0] lines) for the binocular game vs a mean (SD) improvement of 0.16 (0.12) logMAR (mean [SD], 1.6 [1.2] lines) for the patching crossover (P = .73).

Conclusions and Relevance

A binocular iPad game was effective in treating childhood amblyopia and was more efficacious than patching at the 2-week visit. Binocular games that rebalance contrast to overcome suppression are a promising additional option for treating amblyopia.

Trial Registration

clinicaltrials.gov Identifier: NCT02365090.

Risk factors analysis of consecutive exotropia: Oblique muscle overaction may play an important role

To evaluate clinical factors associated with the onset of consecutive exotropia (XT) following esotropia surgery.By a retrospective nested case-control design, we reviewed the medical records of 193 patients who had undergone initial esotropia surgery between 2008 and 2015, and had follow-up longer than 6 months. The probable risk factors were evaluated between groups 1 (consecutive XT) and 2 (non-consecutive exotropia). Pearson chi-square test and Mann-Whitney U test were used for univariate analysis, and conditional logistic regression model was applied for exploring the potential risk factors of consecutive XT.Consecutive exotropia occurred in 23 (11.9%) of 193 patients. Patients who had undergone large bilateral medial rectus recession (BMR) (P = 0.017) had a high risk of developing consecutive XT. Oblique dysfunction (P = 0.001), adduction limitation (P = 0.000) were associated with a high risk of consecutive XT, which was confirmed in the conditional logistic regression analysis. In addition, large amount of BMR (6 mm or more) was associated with higher incidence of adduction limitation (P = 0.045). The surgical methods and preoperative factors did not appear to influence the risk of developing consecutive XT (P > 0.05).The amount of surgery could be optimized to reduce the risk of consecutive XT. The presence of oblique overaction and postoperative adduction limitation may be associated with a high risk of consecutive XT, which may require close supervision, and/or even earlier operation intervention.

The Clinical Course of Intermittent Exotropia With Small Initial Deviation

PURPOSE

To address the clinical course of patients who initially presented with small exodeviation (≥ 10 and ≤ 18 prism diopters [PD]) and to investigate the risk factors associated with progression.

METHODS

The clinical records of patients who were first diagnosed as having intermittent exotropia of small initial deviation from August 2008 to March 2011 and were followed up for 2 or more years were reviewed retrospectively. The initial clinical features associated with the risk of disease progression and surgical intervention were analyzed.

RESULTS

Among 86 patients who met the inclusion criteria, 37 reached a distance deviation of 20 PD or greater and 51 underwent surgical correction for exodeviation during the follow-up. Cumulative percentages of patients whose distance deviation reached 20 PD or greater and who underwent surgery at 24 months were 47.5% and 47.7%, respectively. Mean initial stereoacuity was significantly worse in patients whose final exodeviation progressed to 20 PD or greater. The cumulative probability of surgery was significantly higher in patients who showed constant deviation at the initial examination.

CONCLUSIONS

Nearly half of patients with small exodeviation are expected to reach a final distance deviation of 20 PD or greater or to undergo surgery after 2 years of follow-up. Initial constant deviation was associated with increased cumulative probability of surgical intervention.

Binocular iPad treatment for amblyopia in preschool children

BACKGROUND

Recent experimental evidence supports a role for binocular visual experience in the treatment of amblyopia. The purpose of this study was to determine whether repeated binocular visual experience with dichoptic iPad games could effectively treat amblyopia in preschool children.

METHODS

A total of 50 consecutive amblyopic preschool children 3-6.9 years of age were assigned to play sham iPad games (first 5 children) or binocular iPad games (n = 45) for at least 4 hours per week for 4 weeks. Thirty (67%) children in the binocular iPad group and 4 (80%) in the sham iPad group were also treated with patching at a different time of day. Visual acuity and stereoacuity were assessed at baseline, at 4 weeks, and at 3 months after the cessation of game play.

RESULTS

The sham iPad group had no significant improvement in visual acuity (t4 = 0.34, P = 0.75). In the binocular iPad group, mean visual acuity (plus or minus standard error) improved from 0.43 ± 0.03 at baseline to 0.34 ± 0.03 logMAR at 4 weeks (n = 45; paired t44 = 4.93; P < 0.0001). Stereoacuity did not significantly improve (t44 = 1.35, P = 0.18). Children who played the binocular iPad games for ≥8 hours (≥50% compliance) had significantly more visual acuity improvement than children who played 0-4 hours (t43 = 4.21, P = 0.0001).

CONCLUSIONS

Repeated binocular experience, provided by dichoptic iPad game play, was more effective than sham iPad game play as a treatment for amblyopia in preschool children.

Stereo vision and strabismus

Binocular stereopsis, or stereo vision, is the ability to derive information about how far away objects are, based solely on the relative positions of the object in the two eyes. It depends on both sensory and motor abilities. In this review, I briefly outline some of the neuronal mechanisms supporting stereo vision, and discuss how these are disrupted in strabismus. I explain, in some detail, current methods of assessing stereo vision and their pros and cons. Finally, I review the evidence supporting the clinical importance of such measurements.

To evaluate stereoacuity in patients with acquired esotropia and to determine factors associated with favourable outcomes

AIM

To evaluate stereoacuity in patients with acquired esotropia and determine the factors associated with favorable outcomes.

MATERIALS AND METHODS

A total of 68 subjects aged 6 years and above were included in the study. Thorough clinical evaluation including binocular status examination using the Bagolini-striated glass test, The Netherland Organization (TNO), and Randot stereo test were done. The subjects were divided into two groups 1 and 2, based on the amount of deviation. Statistical analysis of the result was performed.

RESULT

The duration of misalignment in the group with deviation less than or equal to 8 prism diopters (PD) was 1.49 ± 0.86 years, whereas in the group with deviation more than or equal to 10 PD was 4.64 ± 2.99 years (P = 0.000). Among the subjects in group 1, 89.5% achieved fusion and 52.6% had stereoacuity on both TNO and Randot, whereas in group 2 40% achieved fusion and 3.3% stereopsis on both TNO and Randot (one case with only coarse stereopsis). A subanalysis within group 1 revealed a statistically significant difference for the duration of misalignment (P = 0.02), but a marginal difference for the amount of deviation (P = 0.3).

CONCLUSION

A horizontal deviation up to 8 PD was compatible with stereopsis. Also, the duration of constant misalignment affects the attainment of stereopsis despite successful realignment.

Analysis of risk factors for consecutive exotropia and review of the literature

PURPOSE

To evaluate the possible risk factors in patients with consecutive exotropia following esotropia surgery.

METHODS

Medical records of patients who had comitant esotropia surgery between June 1999 and April 2011 were reviewed. Those who developed consecutive exotropia composed the exotropia group; patients matched for age and duration of follow-up who did not develop consecutive exotropia composed the no exotropia group. The charts of the patients were reviewed and possible risk factors for development of consecutive exotropia were investigated.

RESULTS

The average ages of 47 patients in the exotropia group and 54 patients in the no exotropia group were 10.8 ± 8.7 years (range: 1 to 41 years) and 8.5 ± 6.3 years (range: 1 to 30 years), respectively (P = .292). Amblyopia was detected in 31 (66%) and 12 (22.2%) patients in the exotropia and no exotropia groups, respectively (P = .004). Anisometropia was observed in 20 patients (42.6%) in the exotropia group and 5 patients (9.3%) in the no exotropia group (P = .003). Preoperative average esodeviation values were 42.5 ± 8.3 prism diopters (PD) (range: 25 to 60 PD) in the exotropia group and 42 ± 9.4 PD (range: 20 to 65 PD) in the no exotropia group (P = .673). Postoperative deviations were 32.8 ± 23 PD exotropia (range: 10 to 90 PD exotropia) in the exotropia group and 4.4 ± 4.2 PD esotropia (range: 0 to 10 PD esotropia) in the no exotropia group (P = .000). Asymmetric surgery had been performed in 61.7% of the exotropia group (n = 29) and 9.3% of the no exotropia group (n = 5) (P = .000). Limitation of adduction was detected in 14 patients (29.8%) in the exotropia group; none was noted in the no exotropia group (P = .000). The mean interval between the initial surgery and the onset of consecutive exotropia was 11.1 ± 15.1 months (range: 0 to 126 months).

CONCLUSIONS

Anisometropia, amblyopia, asymmetric surgery, and postoperative adduction deficit were associated with the development of consecutive exotropia. Long-term follow-up should be considered because consecutive exotropia can develop after months or years.

Why do only some hyperopes become strabismic?

Children with hyperopia greater than +3.5 diopters (D) are at increased risk for developing refractive esotropia. However, only approximately 20% of these hyperopes develop strabismus. This review provides a systematic theoretical analysis of the accommodation and vergence oculomotor systems with a view to understanding factors that could either protect a hyperopic individual or precipitate a strabismus. The goal is to consider factors that may predict refractive esotropia in an individual and therefore help identify the subset of hyperopes who are at the highest risk for this strabismus, warranting the most consideration in a preventive effort.

New-generation multifocal intraocular lens for pediatric cataract

BACKGROUND/AIMS

To evaluate multifocal intraocular lens (MIOL) implantation in children.

METHODS

This is a retrospective study evaluating refractive, visual and safety results of MIOL in pediatric cataract surgery. Average follow-up was 25.73 ± 10.5 months. Surgery included 12 o'clock clear corneal incision, anterior capsulorhexis, lens material aspiration and MIOL implantation (SN6AD3; Alcon).

RESULTS

We included 34 cataract eyes of 26 pediatric patients aged 2-15 years, of which 14 (54%) were unilateral. Best near visual acuity (BNVA) and best distance visual acuity (BDVA) improved significantly in 100% of eyes (p = 0.0001). BDVA was above 0.8 in 31.25% (5/16) of bilateral cases. Significant stereopsis improvement was observed postoperatively in bilateral cases only (p = 0.01).

CONCLUSION

MIOL implantation is a safe alternative to monofocal pseudophakia for pediatric cataract with a very low complication rate. Significant BNVA, BDVA and stereopsis improvement can be achieved, particularly in bilateral cases.

MESSAGE

This study shows significant BDVA, BNVA and stereopsis improvement, especially in bilateral cases, after MIOL implantation for pediatric cataracts.

Amblyopia and binocular vision

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3%-3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia.

LASIK as an alternative line to treat noncompliant esotropic children

PURPOSE

To assess the safety and efficacy of laser-assisted in situ keratomileusis (LASIK) in facilitating strabismus management in noncompliant children with fully accommodative esotropia.

SETTING

Ebsar Eye Center, Benha University (Benha, Egypt).

METHODS

The study comprised 20 eyes of ten consecutive patients with accommodative esotropia. All patients were noncompliant with glasses and had refractive stability. They received brief general anesthesia and had bilateral LASIK using Wavelight® Algretto Wave® Eye-Q Excimer Laser (Alcon, Inc, Hunenberg, Switzerland) to fully correct their hyperopic refractive errors aiming to achieve orthophoria. Preoperative and postoperative best corrected visual acuity, cycloplegic refraction, angle of squint, and any LASIK complications were recorded. Follow-up period was 9 months.

RESULTS

The age of patients ranged 5.1-9.2 years and the hyperopic error range was +3.5 D to +6.75 D, with anisometropia 2 D or less. No patient had decreased best corrected visual acuity or loss of fusion ability. The postoperative refractive error ranged from -0.75 D to +1.5 D at the end of the study period. All patients achieved orthophoria. No significant intraoperative or postoperative complications were recorded.

CONCLUSION

LASIK appears to be effective and relatively safe to treat accommodative esotropic children by reducing their hyperopic refractive error, however, patient selection is critical. Larger studies with longer follow-up are necessary to determine its long-term effects.

Consecutive exotropia after surgical treatment of childhood esotropia: a 40-year follow-up study

PURPOSE

To determine the incidence of consecutive exotropia (XT) following successful surgical correction of childhood esotropia (ET) and identify factors associated with its development.

MATERIAL AND METHODS

This is a retrospective study of 85 patients with ET, aged 2-24, who underwent strabismus surgery by a single surgeon between 1958 and 1969 in Sweden, until they were successfully aligned to ET within 10 prism dioptre, after primary or reoperation(s). The charts of these patients were reviewed, and data regarding age at onset of strabismus, surgery performed and outcome were recorded. The patients were recalled for a complete orthoptic examination in 2001-2003.

RESULTS

The incidence of consecutive XT in this cohort was 21% (18/85). Patients who had undergone multiple surgeries had a higher risk of developing consecutive XT compared to those successfully aligned with one surgery (p = 0.00036). Restriction of adduction and convergence postoperatively was associated with a high risk of consecutive XT (p = 0.0437). The incidence of consecutive XT did not vary with the level of visual acuity in the operated eye (p = 0.6428). Age of onset, age at surgery and amount of surgery did not appear to influence the risk for developing consecutive XT (p > 0.05).

CONCLUSION

This 40-year postoperative follow-up of patients with childhood ET who underwent strabismus surgery by a single surgeon in Sweden showed that multiple surgeries and presence of postoperative adduction deficit were the most important factors influencing the incidence of consecutive XT after surgery. Presence of uncorrected amblyopia did not alter the prognosis for long-term development of consecutive XT.

The management of childhood esotropia with hyperopia

PURPOSE

Esotropia, especially accommodative estropia (AE), is often seen in patients with hyperopia. In this paper, the authors aim to report the management methods of different types of esotropia in children with hypermetropia and to show the feasibility and efficacy of prismatic correction in the management of small angle of residual esotropia in accommodative estropia.

METHODS

A total of 82 esotropes with hyperopia treated during a 2-year period from 2007 to 2009 were reviewed retrospectively. Data were collected from the medical records.

RESULTS

A total of 25 patients showed pure accommodative esotropes, whereas 45 had partial AE and 12 non-AE. All 25 pure AE patients were corrected fully using glasses alone, and all 12 non-AE patients received surgery. Among the 45 partial AE cases, 35 patients with residual esodeviation of ≤30 PD received prismatic correction, with a success rate of 71.4% (25 of the 35 patients). The remaining 10 children who were not successfully treated with prismatic correction and the other 10 partial AE with residual esodeviation of >30 PD received surgery. The most recent follow-up examination indicated that all the non-surgical children were orthotropia or esophoria or had residual esotropia ≤10 PD. Among the surgical patients, 5 patients (5 in 32 or 15.6%) exhibited unstable alignment during the postoperative follow-up period, and 10 patients (10 in 32 or 31.25%) underwent additional surgery for residual esotropia.

CONCLUSIONS

Treatment of estropia in children with hyperopia includes wearing glasses, glasses combined with prism glasses and surgery. Prismatic correction in the treatment of small angle of residual esotropia in partial AE was feasible and efficacious. Since the follow-up lasted only a year, a long-term follow-up is needed in future studies to investigate the efficiency of the treatments.

Longitudinal changes in refractive error of children with infantile esotropia

Aim

The aim of this study was to quantify changes in refractive status over time in children with infantile esotropia and to analyse a number of clinical factors associated with infantile esotropia to determine how they may affect emmetropisation.

Methods

Longitudinal cycloplegic refraction data were collected for 5-12 years from 143 consecutive children enrolled in a prospective study of infantile esotropia by 6 months of age. Changes in refractive error with age were summarized with descriptive statistics and the influence of amblyopia, undercorrection of hypermetropia, accommodation, and binocular factors on emmetropisation were evaluated by ANOVA and t-tests.

Results

Most had low to moderate hypermetropia on the initial visit (55% had <+3.00 D). While the initial refractive error is similar to normative data, the rapid decrease in hypermetropia that characterizes normal development during the first 9 months of life is absent in children with infantile esotropia. After 9 months of age, children with infantile esotropia follow a developmental course that is similar to the normative course; there is little change in hypermetropia during years 1-7, followed by a decline of approximately -0.5 D/yr beginning at age 8 years. None of the clinical factors examined had a statistically significant effect on the course of refractive changes with age.

Conclusions

Children with infantile esotropia exhibit a different pattern of refractive development than that seen in normative cohorts. The long term changes in refraction observed in children with infantile esotropia suggest that there is a need for long-term clinical follow-up of these children.

Horizontal Lang two-pencil test as a screening test for stereopsis and binocularity

Purpose:

To assess the horizontal Lang two-pencil test as a bedside test to detect gross stereopsis.

Materials and Methods:

Eighty-four strabismic subjects divided into two groups based on the amount of deviation, and 40 normal subjects were studied. Sensory status examination including binocularity and stereopsis were evaluated with Bagolini, Titmus test and the Netherlands organisation for applied scientific research (TNO), Randot, synoptophore and horizontal Lang two-pencil test.

Results:

The subjects in the group with smaller deviation showed better performance on all the four stereo tests and over 90% demonstrated presence of fusion. When compared to TNO and Randot for determining presence of stereopsis, the horizontal Lang two-pencil test demonstrated sensitivity of 100% and 83.9%, specificity of 77.8% and 73.7%, and negative predictive value of 100% and 100% respectively. It also showed 100% specificity as a test for binocularity when compared with the Bagolini striated glass test.

Conclusion:

Horizontal Lang two-pencil test, an easily performed test with a high sensitivity and negative predictive value can be used as a screening test to detect gross stereopsis and binocularity.

Stereoacuity outcomes after treatment of infantile and accommodative esotropia

PURPOSE

To review what is known about the normal maturation of stereoacuity, the stereoacuity deficits associated with infantile and accommodative esotropia, the rationale for making improved stereoacuity a goal of treatment, and strategies for improving stereoacuity outcomes.

METHODS

Studies of stereoacuity maturation during normal development, studies of stereoacuity outcomes after treatment for infantile and accommodative esotropia, and studies of primate models of esotropia are reviewed.

RESULTS

Stereoacuity maturation normally proceeds rapidly during the first year of life. Infantile and accommodative esotropia are associated with profound and permanent disruption of stereopsis. Although rehabilitation of stereoacuity after treatment of esotropia remains a challenge, even the achievement of subnormal stereoacuity may have real benefits to the child.

CONCLUSIONS

Some abnormalities in stereoacuity may exist before the onset of esotropia, but others may result directly from abnormal binocular experience. Several strategies for improving stereoacuity outcomes in esotropia are currently under active investigation. Improved stereoacuity outcomes are associated with better long-term stability of alignment, reduced risk for and severity of amblyopia, improved achievement of sensorimotor developmental milestones, better reading ability, and improved long-term quality of life.

Timing of surgery for infantile esotropia: sensory and motor outcomes

Infantile esotropia is a common ophthalmic disorder in childhood. It is often accompanied by profound maldevelopment of stereopsis, motion processing, and eye movements, despite successful surgical realignment of the eyes. The proper timing of surgery has been debated for decades. There is growing evidence from clinical and animal studies that surgery during the early critical periods enhances sensory and ocular motor development. The Congenital Esotropia Observational Study has defined a clinical profile of infants who will benefit most from early surgery, and several other studies have shown that early surgery does not lead to adverse long-term effects. Clinicians now should consider offering early surgery to patients with large-angle, constant infantile esotropia at or before 10 months of age.

Stereoacuity and ocular associations at age 12 years: findings from a population-based study

PURPOSE

To report the distribution of stereoacuity thresholds and ocular characteristics associated with reduced stereoacuity in a representative sample of 12-year-old Australian children.

METHODS

Stereoacuity thresholds were determined using the three quantitative plates of the TNO test in 2343 children, either unaided or with spectacles, if worn. Logarithm of minimum angle of resolution (logMAR) visual acuity was measured. Cycloplegic autorefraction (using cyclopentolate), cover testing, and dilated fundus examination were performed. Reduced stereoacuity was defined as > 120 arcsec. Myopia was defined as spherical equivalent refraction (SER) < or = -0.50 D hyperopia as spherical equivalent refraction > or = +2.0 D, anisometropia as spherical equivalent refraction difference between eyes > or =1.00 D, and astigmatism as cylinder > or = 1.0 D.

RESULTS

Stereoacuity was based on unaided visual acuity in 1975 children (84.3%) and on spectacle-corrected visual acuity in 368 children (15.7%); 87 children (3.7%) had reduced stereoacuity. Amblyopia was the most common identifiable cause, accounting for 32%, followed by strabismus (15%) and anisometropia (14%). Presence of anisometropia was significantly associated with reduced stereoacuity; 78.6% of anisometropic children achieved normal stereoacuity versus 98.9% without anisometropia (p < 0.0001).

CONCLUSIONS

Reduced stereoacuity was relatively uncommon in a population of 12-year-old Australian children. Its functional and psychosocial impact on individuals and on the whole population remains uncertain.

Effects of perceptual learning on local stereopsis and neuronal responses of V1 and V2 in prism-reared monkeys

Visual performance improves with practice (perceptual learning). In this study, we sought to determine whether or not adult monkeys reared with early abnormal visual experience improve their stereoacuity by extensive psychophysical training and testing, and if so, whether alterations of neuronal responses in the primary visual cortex (V1) and/or visual area 2 (V2) are involved in such improvement. Strabismus was optically simulated in five macaque monkeys using a prism-rearing procedure between 4 and 14 wk of age. Around 2 yr of age, three of the prism-reared monkeys ("trained" monkeys) were tested for their spatial contrast sensitivity and stereoacuity. Two other prism-reared monkeys received no training or testing ("untrained" monkeys). Microelectrode experiments were conducted around 4 yr of age. All three prism-reared trained monkeys showed improvement in stereoacuity by a factor of 7 or better. However, final stereothresholds were still approximately 10-20 times worse than those in normal monkeys. In V1, disparity sensitivity was drastically reduced in both the trained and untrained prism-reared monkeys and behavioral training had no obvious effect. In V2, the disparity sensitivity in the trained monkeys was better by a factor of approximately 2.0 compared with that in the untrained monkeys. These data suggest that the observed improvement in stereoacuity of the trained prism-reared monkeys may have resulted from better retention of disparity sensitivity in V2 and/or from "learning" by upstream neurons to more efficiently attend to residual local disparity information in V1 and V2.

Increasing muscle strength as a treatment for strabismus: sustained release of insulin-like growth factor-1 in rabbit extraocular muscle

PURPOSE

Currently, no drug treatment is available for strengthening underacting extraocular muscles (EOM) in strabismus. We showed previously that single injections of insulin-like growth factor (IGF-1) result in significant but short-term increases in muscle force generation. This study examined the effects of sustained release of IGF-1 on force generation in rabbit superior rectus muscles.

METHODS

In adult rabbits, slow-release pellets containing IGF-1 were implanted on the global side of one superior rectus muscle. After 1 week, or 1, 2, 3, or 6 months, treated and control muscles were examined for force generation using an in vitro physiology apparatus. All muscles were prepared for histology and mean myofiber cross-sectional areas were determined.

RESULTS

One and 3 months after pellet implantation, treated muscles generated significantly greater force than contralateral control muscles, whereas at 2 months, no significant difference was found. Force per cross-sectional area (mN/cm(2)) at 3 months also increased significantly in the treated muscles. Mean muscle cross-sectional area increased significantly after 1, 2, and 3 months of sustained exposure to IGF-1 compared with controls. After an additional 3 months without IGF-1 exposure, mean cross-sectional areas were significantly greater than controls but significantly reduced compared with areas at 1, 2, and 3 months.

CONCLUSIONS

IGF-1 appears to be highly effective in increasing muscle force generation. Because slow release of IGF-1 results in sustained increases in EOM force generation, it may be a potentially useful alternative to surgical resection procedures because it avoids many of the potential long-term biomechanical hazards of resection surgery.

Factors affecting sensory functions after successful postoperative ocular alignment of acquired esotropia

PURPOSE

We sought to evaluate the sensory status of patients with acquired esotropia who were able to re-establish stable alignment by optical correction and surgery and to determine the possible predictors of the different sensory outcomes.

METHODS

Thirty-four successfully aligned esotropic patients were included in the study. Preoperative evaluation comprised history taking, measurement of visual acuity, evaluation of the sensory status (using the Worth 4-Dot test, and the Titmus Stereo test), measurement of ocular deviation, cycloplegic refraction, and fundus examination. All patients underwent successful surgical alignment to within 10 prism diopters (Delta) of orthotropia. At each postoperative follow-up visit, the sensory functions and ocular alignment were assessed. Statistical analysis of the results was performed.

RESULTS

Among the 34 patients included in the study, 62% achieved fusion, 17% had diplopia, 15% had suppression, and 6% had a variable response to the Worth 4-Dot test at 6 months after surgery. Stereopsis was achieved in 32% as determined by the Titmus Stereo test. Statistical analysis revealed a significant relationship between the sensory status and the duration of strabismus (P=.00002), the age at surgery (P=.00289), and postoperative ocular alignment (P=.02211).

CONCLUSION

Early surgical and optical ocular alignment of strabismic patients is advisable to achieve fusion and stereopsis.

Disruption and reacquisition of binocular vision in childhood and in adulthood

PURPOSE OF REVIEW

This article reviews the most recent studies that address the loss of and restoration of binocular vision in childhood and adulthood and summarizes recent changes in treatment approaches.

RECENT FINDINGS

Studies during the last two years support the idea of continued plasticity of the binocular visual system throughout life. Children and adults with strabismus onset following binocular vision maturation are susceptibility to a permanent disruption of stereopsis and sensory fusion. Plasticity of the binocular visual system, however, also means continued restorability of function. Despite a rather short critical time interval for restoration of normal function (three months in children and 12 months in adults), peripheral or extramacular binocular visual function can be restored in most patients whose onset of disruption follows binocular maturation.

SUMMARY

Stereoacuity loss can occur in the visually mature patient who develops strabismus later in life and delay of treatment can be deleterious to the restoration of normal macular binocular vision. However, despite any delay of treatment, most patients with strabismus acquired following binocular vision maturation will manifest some stereoacuity or sensory fusion following eye realignment. These findings suggest all patients with strabismus need to have their eyes aligned, either surgically or optically, to maximize their binocular vision outcome.

Amblyopia: diagnostic and therapeutic options

PURPOSE

To provide an overview of the current state of knowledge of amblyopia and highlight recent advances in diagnosis and treatment.

DESIGN

Review of literature and perspective.

METHODS

MEDLINE search for amblyopia, with a review of all recent literature adding authors' personal perspectives on the findings.

RESULTS

Increased awareness of amblyopia and better screening techniques are required to identify children who are at risk for amblyopia at a younger age. Randomized, controlled trials have established atropine penalization as a viable alternative to occlusion therapy, have suggested that less treatment may be better tolerated and as effective as more traditionally used dosages, and have found no compelling evidence that treatment is beneficial clinically for older (over age 10) children with amblyopia.

CONCLUSION

Early detection and treatment of amblyopia can improve the chances for a successful visual outcome. Considering that the conditions that place a patient at risk for amblyopia can be identified, that amblyopia responds to treatment, and that well-tolerated treatments for the condition are now recognized, it is not unreasonable to imagine that, in the near future, severe amblyopia could be eliminated as a public health problem.

Decision analysis with Markov processes supports early surgery for large-angle infantile esotropia

PURPOSE

To assess tradeoffs in time spent with aligned visual axes or stereopsis and risked reoperations between three strategies for the treatment of large-angle infantile esotropia: first surgery at 6, 24, or 48 months of age.

DESIGN

Decision analysis.

METHODS

We simulated three hypothetic cohorts of children with this condition until their eighth year. Potential achievement of stereopsis, the diagnosis of dissociated vertical divergence or inferior oblique overaction, and various complications were modeled. Probability estimates were obtained from a comprehensive literature review. Analyses aimed to determine the strategy that was associated with longer time spent with aligned eyes and/or stereopsis and fewer reoperations.

RESULTS

Eight-year-old children are expected to spend 72.6 vs 58.0 vs 37.8 months with aligned eyes and 26.8 vs 9.0 vs 1.5 months with stereopsis and to receive on average 1.76 vs 1.67 vs 1.46 surgeries, if they first underwent operation at 6 vs 24 vs 48 months, respectively. Children at 8 years are expected to have stereopsis at the rate of 36.1% vs 17.2% vs 5.1%, respectively. Operation at 6 months instead of 48 months is expected to yield an additional 9% of total follow-up time in health states with eye alignment and 11% in health states with stereopsis, per 5% increase in risk for extra operations (5% and 7%, respectively, per 5% increase in risk for operation at 6 vs 24 months). Wide-range sensitivity analyses and long-term projections point to the same direction.

CONCLUSION

Given the benefit/risk tradeoffs, it is probably warranted to attempt to correct large-angle infantile esotropia as early as possible.

Childhood esotropia

PURPOSE

To review the most recent studies on childhood esotropia, and to summarize recent changes in treatment approach.

RECENT FINDINGS

Constant, large-angle esotropia present in the first few months of life may be suitable for early surgery. Earlier surgical intervention, within the first several months of onset, is associated with better sensory outcomes. Similar findings are true for accommodative esotropia; children treated within the first 4 months of constant esotropia have better outcomes. Refractive surgery has been used successfully in adult patients to treat accommodative esotropia.

SUMMARY

New developments pertaining to infantile esotropia have helped clarify the pathophysiology of the condition and the best treatment approaches. Abnormal binocular visual input early in life contributes to poor outcomes in both infantile and accommodative esotropia.