We thank Chhablani and associates for their interest in our article and their comments, which mainly concern the methodology of our study. They expressed concern that some of our patients with intermittent exotropia may have a normal range of ocular torsion, as shown in several previous studies on fundus torsion in normal individuals. We agree with this comment. However, the ultimate goal of our study was to assess not the actual degree of ocular torsion, but rather the distribution of ocular torsion in normal controls and patients with intermittent exotropia. Therefore, what we pointed out in our study was the fact that the incidence of ocular torsion (either extorsion or intorsion) was significantly higher in the intermittent exotropia group than in the normal control group. Most of our patients with intermittent exotropia (70%) had no torsion, which means, as Chhablani and associates mention, most of them might have had a normal range of ocular torsion. One should understand that the normal range of ocular torsion may include no torsion, intorsion, or extorsion. The meaningful finding in our study was that the ocular extorsion and intorsion was much more frequent in patients with intermittent exotropia compared with normal individuals.
With regard to the clinical measure of the severity of exotropia, we acknowledge that the Newcastle scoring system can reflect the clinical severity of intermittent exotropia. However, the Newcastle scale can be useful in mild intermittent exotropia, but may be less useful in severe exotropia. Only a few of our patients were thought to fall into the category of mild intermittent exotropia. For that reason, we used the amount of exotropia and the degree of stereopsis instead of the Newcastle score as clinical variables reflecting the severity of exotropia.
Finally, we are very surprised that Chhablani and associates suggest that the near stereopsis would be clinically insignificant in patients with intermittent exotropia. Average Titmus near stereoacuity of our 150 patients with intermittent exotropia was 93.5 arc seconds, which could be regarded as relatively poor stereoacuity. Depending on the severity of strabismus, the level of Titmus stereoacuity is highly variable even in patients with intermittent exotropia. Therefore, we believe that the stereopsis at near could reflect the severity of exotropia in clinical practice, unless the degree of strabismus of certain patients is uniformly very mild.