Postoperative Stabilization of the Strabismic Angle in Intermittent Exotropia

PURPOSE: To analyze the postoperative strabismic angle for five years or more and to investigate when the angle stabilized in intermittent exotropia. METHODS: We retrospectively reviewed the clinical records of 89 patients who had undergone surgery for intermittent exotropia. The postoperative strabismic angles measured were analyzed at one-year intervals up to five years postoperatively. We divided them into two groups according to their age at the time of surgery. Group 1 was less than 5 years of age, while Group 2 participants were 5 years of age or older. RESULTS: For our 89 total patients, average exo-angles were 7.8 +/- 7.26, 7.9 +/- 7.51, 9.5 +/- 7.05, 10.1 +/- 6.87, and 9.4 +/- 6.90 prism diopters at one, two, three, four, and five years postoperatively, respectively. Average exo-angles between postoperative year one and year three, as well as between postoperative year two and year three, were statistically significant (p = 0.015, 0.022). However, the angles were not statistically significant between postoperative year three and year four or between years three and five, respectively (p = 0.707, p = 0.948). The stabilization characteristics of the angle were somewhat different according to age group. In Group 1, the average exo-angle in postoperative years one and three were statistically significant (p = 0.016), but the angle in the same period was not statistically significant in Group 2 (p = 0.203). CONCLUSIONS: There was no significant interval change after three years postoperatively in intermittent exotropia, but if the patient's age at surgery was 5 years or higher, no significant change of exo-angle was found following postoperative year one in this study.

Surgical Outcomes of Intermittent Exotropia as a Function of Strabismic Angle

PURPOSE: To analyze postoperative results of intermittent exotropia as a function of the difference in strabismic angles measured immediately and another time prior to the surgery. METHODS: We reviewed the clinical records of intermittent exotropia patients who received surgery and had differences greater than or equal to 10 prism diopters (PD) between the last preoperative measurement of strabismic angle and another previous measurement. After applying various exclusion criteria, 66 patients were entered into our study. At the last follow-up visit after surgery, we divided postoperative results into 3 categories: (1) poor; with greater than 10 PD of esotropia or angle of exodeviation of 20 PD or more (2) moderate; with 6-10 PD of esophoria/tropia or 10-19 PD exodeviation, or (3) good; with 1-5 PD of esophoria/tropia or an angle of exodeviation less than 10 PD, or orthophoria. RESULTS: Good results were higher in patients where the difference in strabismic angle was 10 PD or greater between the last measurement and any other earlier measurement. CONCLUSIONS: In cases of Intermittent exotropia where the last preoperative value of strabismic angle was greater than any previous preoperative measurement, surgical dosage based on the last preoperative measurement yielded better results.

New Method for Measurement of Strabismic Angle using Corneal Reflex and Photograph

PURPOSE: We introduce a new method for measurement of strabismic angle using corneal reflex and photograph, and report its clinical results. MATERIAL AND METHOD: The subjects were 5 orthotropic persons, 3 patients with eso-deviation of 20 prism and 30prism respectively, and 5 patients with exo-deviation of 15 prism, 20 prism, 30 prism, and 40 prism, respectively. While subject fixates distant target, we place the illuminator 1m in front of the subject and take the pictures. We got the ratio of corneal diameter and distance between right-side limbus and corneal reflex, then the difference between right and left. RESULT: If strabismic angle is Y and the difference (%) between the deviation ratio of right and left is X, Y=1.67x14.03. CONCLUSION:This new method can be used in patients of poor compliance, patients with poor visual acuity and measurement of distant strabismic angle.

Analysis about Diffe rences of Preoperative Measurement of Strabismic Angle in Exodeviation

Preoperarive measurement of strabismic angle is most important procedure in determining the amount of surgery.But measured angles are not always the same at each examination, which is quite a steress to both the operator and the patient because additional examination has to be done for accurate determination of surgical amount and also because the confidence for planned amount of surgery may be reduced.Therefore we investigated the variance of preoperative measurements and evaluated the necessity of repeated examinations. We compared the variance of measurement and investigated the bias and reliability of repeated examinations, from 104 patients who were examined initially by a resident at first visit and examined repeatedly at least 3 times before operation by a specialist.Also, the degree of variance in measurement and its relation with postoperative result were evaluated. The differences in measurement between resident and specialist was average 2.37 prism diopters, which was not significant on reliability analysis.Also, there were no significant differneces among 3 measurements by specialist. The degree of variance decreased with increasing age and the larger the degree of variance in measurement, the larger the deviation which may be remained postoperatively. The results suggest that the angle of deviation measured by resident is reliable and repeated measurements do not differ significantly[p>0.05], and also confirms that the variation of these measurements is an important factor which can influence postoperative results.

Digitalized Videographic Measurement of Strabismic Angle

Current using strabismic angle measurement techniques require examiners experience and subjective decision. The accuracy between observers and intra-observer is limited by the minimum eye movement that the examiner can detect with naked eye. Horizontal strabismic angles with 35 comitant strabismus patients were measured using precise digital signals converted by digital frame grabber and image processing software in a 32 bit microcomputer. Strabismic angle calculated using digital method was compared with that of prism-cover method. The slope of the regression line was 1.1054; the Y-intercept was 1.3870PD. The coefficiency of variation to verify its reproducibility for measurements of total variability in 35 strabismic patients was 3.71%. The strabismic angle measurement with digital frame grabber seems to be relatively precise and clinical application will be available in measuring horizontal and vertical strabismic angel.