The incidence, clinical features, and management of essential infantile esotropia in the United Kingdom. A British Ophthalmology Surveillance Unit (BOSU) study

BACKGROUND/OBJECTIVES

A national study was undertaken through the British ophthalmology surveillance unit (BOSU) to determine the incidence, presenting features and management of essential infantile esotropia (EIE) in the UK.

METHODS

Data from a prospective national observational study of newly diagnosed EIE presenting to clinicians in the United Kingdom over a 12-month period were collected. Cases with a confirmed diagnosis by a clinician of a constant, non-accommodative esotropia ≥20 prism dioptres (PD), presenting at ≤12 months, with no neurological or ocular abnormalities were identified through BOSU. Follow-up data were collected at 12 months.

RESULTS

A total of 57 cases were reported giving an incidence of EIE of 1 in 12,828 live births. The mean age of diagnosis and intervention were 7.05 ± 2.6 months (range 2-12) and 14.7 ± 4.9 months (range 6.5-28.1), respectively. Management was surgical in 59.6%, botulinum toxin alone in 22.8%, and 17.5% were observed. The preoperative angle of esotropia was smaller in the observation group (P = 0.04). The postoperative angle of esotropia was not statistically significant between botulinum toxin or surgery (P = 0.3), although the age of intervention was earlier in the botulinum group (P = 0.007). Early intervention (before 12 months of age) did not influence the post-intervention motor outcomes between 0 and 10 prism dioptres of esotropia (P = 0.78).

CONCLUSIONS

The incidence of EIE in the UK is considerably lower than reported in other population-based studies. The preferred method of treatment was surgical with earlier intervention in those treated with botulinum toxin. An early age of intervention (<12 months) did not influence motor outcomes.

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.

Relationship between stereopsis outcome and timing of surgical alignment in infantile esotropia

PURPOSE

To clarify the relationship between stereopsis outcome and timing of surgical alignment in infantile esotropia.

METHODS

The medical records of otherwise healthy patients with infantile esotropia who underwent surgery by 8 years of age were divided into the following groups according to age at time of surgery: very early surgery (≤8 months), early surgery (>8 to ≤24 months) and late surgery (>24 months). Binocular response and stereopsis were compared between groups.

RESULTS

A total of 76 patients were included: 22 in the very early group, 30 in the early group, and 24 in the late group. Binocular response at near was found in 96% of the very early group and in 80% of the early group, significantly higher than the 50% of the late group (P < 0.001 and P < 0.05 [Dunn test], resp.). Stereopsis was present in 77% of the very early group, significantly higher than the 20% of the early group and 13% of the late group (P < 0.001 [Dunn test]). A significant correlation was also found between age (months) at surgery and stereopsis (seconds) outcome (logarithmic fit: y = 2539.4ln(x) + 147.2; R² = 0.2691; P < 0.001).

CONCLUSIONS

In this study cohort, earlier surgery was associated with better binocularity in patients with infantile esotropia. Our results suggest that very early surgery, at ≤8 months, can improve the chance for postoperative stereopsis, with the caveat that some infants might have had spontaneous esotropia resolution.

Stereopsis: are we assessing it in enough depth?

The assessment of stereoacuity is an integral part of the ophthalmic assessment, with the responses used to inform clinical management decisions. Stereoacuity impacts on many aspects of life, but there are discrepancies reported where people without measurable stereoacuity report appreciating 3-D vision. This could be due, in part, to the presentation of the stimuli. A literature review was undertaken to evaluate current assessment techniques, how they relate to patient outcomes, identify the limitations of current tests and discuss how they could be improved. Recent evidence has been collated on currently available tests, used commonly within vision clinics, with normative data provided allowing responses to the tests to be interpreted. The relevance of the results is evaluated in relation to a range of outcomes, where a reduced level of stereopsis has a negative impact on the ability of an individual to perform many tasks, and can lead to an increase in difficulty interacting in the world. Current tests are limited in the aspects of stereoacuity they assess and their ability to precisely measure stereopsis. The world is not static, yet clinical tests are limited to measuring static stereoacuity, even though higher grades of depth perception can be identified in the presence of changing depth. Presentation methods of stereoacuity tests have remained similar over time, with a limited number of disparity levels assessed. New assessment methods are becoming available that include automated staircase testing to present multiple levels of disparity using digital technology. Current clinical tests are limited in their presentation, and are poor at detecting/measuring stereoacuity in those with limited stereopsis. Given the relevance of the stereoacuity measurement to management choices and functional outcomes, new testing methods would be beneficial to fully assess stereoacuity, both static and dynamic.

Real stereopsis test using a three-dimensional display with Tridef software

PURPOSE

To investigate horizontal image disparity in three-dimensional (3-D) perception using 3-D animations in normal control patients and patients with intermittent exotropia, anisometropic amblyopia, and partially accommodative esotropia.

MATERIALS AND METHODS

A total of 133 subjects were included. Stereopsis was measured using the Titmus Stereo test (Stereo Optical Inc., Chicago, IL, USA) and a 3-D stereopsis test with a 15 inch 3-D display laptop, adjusting 3-D parameters of 0 mm horizontal disparity to 15 mm horizontal disparity.

RESULTS

When compared with normal controls, the average threshold of the 3-D stereopsis test was significantly reduced for esotropia patients (p<0.001) and for anisometric amblyopia patients (p<0.001), compared to normal controls. No significant difference was observed between normal controls and intermittent exotropia patients (p=0.082). The 3-D stereopsis test was correlated with the Titmus Stereo test (Spearman's rho=0.690, p<0.001). Mean difference in stereoacuity was 1.323 log seconds of arc (95% limits of agreement: 0.486 to 2.112), and 125 (92.5%) patients were within the limits of agreement.

CONCLUSION

This study demonstrated that a 3-D stereopsis test with animation is highly correlated with the Titmus Stereo test; nevertheless, 3-D stereopsis with animations generates more image disparities than the conventional Titmus Stereo test. The 3-D stereopsis test is highly predictive for estimating real stereopsis in a 3-D movie theater.

Stereopsis and long-term stability of alignment in esotropia

PURPOSE

Recent studies of infantile and accommodative esotropia (ET) have focused on stereoacuity as a final outcome measurement for judging the success or failure of treatment. The purpose of the present study was to extend this approach by evaluating whether the presence of stereopsis developing immediately after surgical alignment or optical correction plays a role in maintenance of long-term alignment.

METHODS

Random-dot stereoacuity was assessed within 3 months of initial surgical alignment in 70 children with infantile ET and within 3 months of initial optical correction in 66 children with accommodative ET. At > or = 5 years of age, adverse outcomes were assessed including loss of alignment, amblyopia, and nil stereopsis. Risk-factor analysis was used to evaluate whether early nil stereopsis increased the risk for subsequent adverse outcomes.

RESULTS

In the infantile ET cohort, early nil stereopsis was associated with a 3.6 times (95% confidence interval [CI] 2.4 to 4.1) greater risk of surgery for recurrent ET or consecutive exotropia and a 4.2 times (95% CI 3.3 to 4.4) greater risk for nil stereopsis at > or = 5 years of age. In the accommodative ET cohort, early nil stereopsis was associated with a 17.4 times (95% CI 3.3 to 32.2) greater risk of surgery for ET and a 32.2 times (95% CI 15.8 to 35.6) greater risk for nil stereopsis at > or = 5 years of age.

CONCLUSION

Treatment protocols designed to optimize stereoacuity outcomes promote long-term stability of alignment.