SOME OBSERVATIONS ON INTERMITTENT EXOTROPIA

Compared performance of Spot and SW800 photoscreeners on Chinese children

Purpose

To evaluate the effectiveness of Spot photoscreener and SW800 vision screener in detecting amblyopia risk factors in Chinese children between 4 and 6 years of age.

Methods

One hundred and thirteen children (226 eyes) underwent complete ophthalmologic examination, cycloplegic retinoscopy refraction, prism cover tests and photoscreen using both Spot (v2.1.4) and SW800 (v1.0.1.0) photoscreeners. The agreement of results obtained from photoscreener and retinoscopy was evaluated by paired t-test as well as Pearson correlation test. The sensitivity and specificity of detecting amblyopia risk factors were calculated based on the American Association of Pediatric Ophthalmology and Strabismus 2013 guidelines. The overall effectiveness of detecting amblyopia risk factors by using either photoscreener was analysed by receiver operating characteristic (ROC) curves.

Results

A strong linear agreement was observed between Spot and retinoscopy (p<0.01) in aspects of spherical equivalent (SE, Pearson’s r=0.95), dioptre sphere (DS, r=0.97), dioptre cylinder (DC, r=0.84) and horizontal deviation (Hdev, r=0.91), with overall −0.17 D myopic shift of SE. Significant correlation was also shown between SW800 and retinoscopy (p<0.01) in aspects of SE (r=0.90), DS (r=0.93), DC (r=0.82) and Hdev (r=0.80), with overall −0.12 D myopic shift of SE. The overall sensitivity and specificity in detecting amblyopia risk factors were 94.0% and 80.0% for Spot and 88.8% and 81.1% for SW800.

Conclusion

The measurements of Spot and SW800 photoscreener showed a strong agreement with cycloplegic retinoscopy refraction and prism cover tests. The performance of both screeners in detecting individual amblyopia risk factors is satisfactory. ROC analysis indicates that the Spot and SW800 performed very similarly in detecting amblyopia risk factors.

Single vision during ocular deviation in intermittent exotropia

Intermittent exotropia is a common oculomotor anomaly where one eye intermittently deviates outwards. Patients with this type of strabismus are often not aware of the exodeviation and do not usually experience diplopia. In this review, we discuss what is known about the cortical mechanisms which achieve single vision during exodeviation in this condition, and highlight some outstanding questions.

Design and synthesis of low molecular weight compounds with complement inhibition activity

An attempt was made to synthesize a series of non-cytotoxic low molecular weight compounds of varying substitutions and functionalities having pharmacophore activity like carbonyl compounds, carboxylic acid and bioisosteres like tetrazole and phenyl acrylic acid. The in vitro assay of these analogues for the inhibition of complement activity revealed significant inhibitory activity for varying substituents and, particularly, for bioisosteres, that is, tetrazole and phenyl acrylic acid derivatives.

Stimulus and response AC/A ratios in intermittent exotropia of the divergence-excess type

Objective infrared recording devices were used to measure simultaneously and continuously both accommodation and accommodative vergence to near stimuli in 4 subjects with intermittent exotropia of the divergence-excess type (2 simulated and 2 true). In addition standard clinically determined stimulus accommodative convergence to accommodation (AC/A) ratios were measured. Results showed the mean group response AC/C ratio to be 5.9/1 (range 4.5-8.0/1) with no differences between true and simulated divergence-excess. Similar AC/A ratios were found after 45 minutes of monocular occlusion. Our results clearly demonstrate relatively normal response AC/A ratios in these subjects. Thus, contrary to what is believed by many clinicians, the reduced ocular deviation at near compared with distance vision cannot be attributed primarily to an abnormally high AC/A ratio. We believe than fusional convergence after-effects and/or proximal convergence effects contribute to inflate the clinically determined stimulus AC/A ratios.