Clinical study on distance and near stereoacuity changes in patients with different types of strabismus before and after surgery / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To discuss and evaluate how different types of strabismus impact on the recovery of distance and near stereoacuity after strabismus surgery. METHODS:We selected 72 cases of strabismus who were treated in our hospital. They were divided into four groups: Group 1 as constant non - accommodative esotropia;Group 2 as intermittent exotropia; Group 3 as constant exotropia; Group 4 as exotropia V sign with inferior oblique hyperfunction. The distance stereoacuity were examined by synoptophore and the near stereoacuity was examined by Shaoming Yan's stereogram. Above examination data was collected and recorded before surgery,7d,1,3,and 6mo after surgery. RESULTS: The 72 patients' distance and near stereoacuity were significantly improved after their surgery, compared with their previous binocular vision. The improvement showed statistical significant(P<0.05). The recovery of Group 2's distance and near stereoacuity had been proved superior to that of Group 1, Group 3, and Group 4. The changes in the distance and near stereoacuity of Group 2 were statistically significant (P<0 05). There were no statistically significant changes in the distance and near stereoacuity of Group 1, Group 3, and Group 4 after the surgeries(P>0.05). The damage of distance stereoacuity (0 cases) was more severe than the damage of near stereoacuity (19 cases, 26%). After the surgeries, near stereoacuity's (51 cases, 71%) recovery was significantly superior to the distance stereoacuity's recovery(17 cases,24%). At 1mo after the surgeries,the improvement of distance and near stereoacuity was most obvious. CONCLUSION:Postoperative recovery of distance and near stereoacuity varies as per strabismus type. Intermittent exotropia's patients show the best recovery of distance and near stereoacuity after the surgeries. The clinical results on the recovery of distance and near stereoacuity after surgery for constant non -accommodative esotropia, constant exotropia and exotropia V sign with inferior oblique hyperfunction are consistent. As the distance stereoacuity of the patients with strabismus has more severe damage,the recovery of near stereoacuity is superior to that of distance stereoacuity.

Distance Stereoacuity by Frisby Davis Distance Stereotest after Surgery in Intermittent Exotropic Patients

PURPOSE: To compare distance stereoacuity in patients with intermittent exotropia before and after surgery using the Frisby Davis distance stereotest (FD2), and to determine the preoperative factors that affect the postoperative distance stereoacuity. METHODS: A total of 56 patients with intermittent exotropia were examined for the present study. To determine preoperative factors that affect postoperative distance stereoacuity, age, gender, distance control, and presence of fusion were measured. The deviation angle was measured at near and at distance by using a prism cover test. Distance stereoacuity was measured with the FD2 test. RESULTS: According to the results of the FD2 test, the mean preoperative distance stereoacuity of patients was 64.7 +/- 76.1 sec of arc, and improved to 53.6 +/- 85.9 sec of arc postoperatively. The distance stereoacuity improved notably from 63.0 to 40.0 sec of arc after the successful surgery. No significant correlation was present between type of surgery, distance control, presence of fusion, and postoperative improvement of distance steroacuity. CONCLUSIONS: Decreased stereoacuity in intermittent exotropic patients improved postoperatively, and the FD2 test was valuable in evaluating the stereoacuity in intermittent exotropic patients pre- and postoperatively.

Normal Distance Stereoacuity by Age Assessed by the Frisby Davis Distance Stereotest

PURPOSE: To determine the range of normal distance stereoacuity in populations with normal vision and the change of distance stereoacuity with age using the Frisby Davis Distance (FD2) stereotest and to evaluate the influence of monocular cues on the FD2 test. METHODS: Ninety-eight subjects between 4 and 73 years old who had no ocular or neurologic diseases were examined. Distance stereoacuity was measured binocularly and monocularly with the FD2 test. RESULTS: According to the results of the FD2 test, the mean distance stereoacuity of patients was 14.74+/-6.02 sec of arc. The monocular threshold with the dominant eye was 182.09+/-58.13 sec of arc. Subjects between 21 and 30 years old showed the best distance stereoacuity of 10.67+/-3.20 sec of arc. A significant decline in distance stereoacuity and monocular threshold were seen in subjects older than 61 (p<0.001). CONCLUSIONS: The normal distance stereoacuity using the FD2 was 14.74+/-6.02 sec of arc, and significant reductions of stereoacuity and monocular threshold were seen in subjects older than 61. Therefore, we have to consider the effect of age on stereoacuity when performing the FD2 test. To take monocular cues into account, the FD2 test should be performed under both binocular and monocular conditions.

Stereoacuity of Normal Subjects Assessed by Frisby Davis Distance Stereotest

PURPOSE: The Frisby Davis Distance (FD2) Stereotest has been introduced to measure distance stereoacuity. The purpose of this study is to establish the range of normal distance stereoacuity responses on the FD2 Stereotest in a normal population. METHODS: This study comprised 65 subjects. All had best corrected vision of 20/25 or better in each eye at distance, 1.0 diopters or less of anisometropia, 8 prism diopters or less of phoria on alternate cover test at both distance and near, binocular fusion on the Worth four dot test and stereopsis on Titmus test. Distance stereoacuity was measured using the FD2 stereotest. RESULTS: The mean age of the subjects was 18.6 years (range, 3 to 59). The mean stereoacuity for distance was 15.61+/-10.41 sec (seconds of arc), and the mean stereoaucity of the subject over 10 years old was 12.98+/-6.86 sec. Results of the test-retest variability as well as of different test distances revealed no statistically significant differences. Of 60 subject with one eye closed, 11 (18.3%) of them detected the disparity of 200 sec but none could detect smaller disparity except one. CONCLUSIONS: The FD2 Stereotest is reliable test without test distance variance. The results of this study can be used as a normative data of distance stereoacuity by FD2.

The Usefulness of the Worth 4-Dot Test under Room Light On and Off in Intermittent Exotropes

PURPOSE: It is known that fusion is promoted in the presence of a peripheral fusion clue in patients with intermittent exotropia, X(T). Therefore, this study compared the results of the Worth 4-dot test (W4D) with the room lights on and off in order to determine the status of the binocular function. METHODS: The W4D test was performed with lights on and off, and the polarized 4-dot test (P4D) was administered in 52 X(T) patients. RESULTS: Among these 3 tests, the fusion rate was the lowest with distance in the W4D with the lights off at 9.6%, which was followed by the W4D with the lights on at 26.9% and the P4D at 57.7%. The fusion rate of the W4D with the lights on in the patients with a distance stereoacuity better than 120 seconds of arc (") was 50%, which was significantly higher than the 18.4% observed in the patients with a stereoacuity at 120" or worse (P=0.023). Among the 14 patients who showed fusion with the distance W4D with the lights on, 10 could not fused with the W4D with the lights off. Therefore, a weak motor fusion was observed in 71.4 % of these 14 patients. CONCLUSIONS: It is possible to verify the more natural condition of the binocular sensory function of patients with X(T) using either the P4D or the W4D with the lights on rather than with the lights off. Furthermore, the W4D test with the lights on can be performed together with and be compared with that conducted with the lights off, for a better understand of the degree of motor fusion.

The Usefulness of Titmus Test and Distance Stereoacuity Using B-VAT(R) in Intemittent Exotropes

PURPOSE: Stereoacuity test is commonly used to determine the status of sensory function in patients with strabismus. We performed Titmus test and Mentor B-VAT II videoacuity tester in patients with basic or simulated divergence excess type intermittent exotropia {X(T)}, before and after surgery, to determine the effectiveness of near stereoacuity and the correlation between near stereoacuity and distance stereoacuity. METHODS: Near stereoacuity was measured using Titmus test and distance stereoacuity was measured using a Mentor B-VAT II videoacuity tester, before and after surgery, in 41 patients with X(T). RESULTS: The stereoacuity according to Titmus test was improved from a preoperative average of 70 seconds of arc to postoperative average of 60 seconds; however, this improvement was not statistically significant (P=0.38). Distance stereoacuity was significantly improved from a preoperative average of 221 seconds to a postoperative average of 60 seconds (P=0.001). No significant correlation was present between preoperative near stereoacuity and distance stereoacuity (P=0.99). CONCLUSIONS: Titmus test was not effective in determining the status of sensory function before and after surgery in patients with basic or simulated divergence excess type X(T). We believe that distance stereoacuity is effective in determining the status of sensory function.

Comparison of Distance and Near Stereoacuity in Normal and Intermittent Exotropic Children

PURPOSE: The purpose of this study was to evaluate, and compare the mean value of near and distance stereoacuity in normal and intermittent exotropia {(X)T}children. METHODS: This study included 86 children, 43 normal children and 43(X)T children ranging in age from 4 to 10 years. Near stereoacuity was assessed by Titmus circle and Randot circle tests. Distance stereoacuity was measured with the Random Dot and Circles tests on the Mentor B-VAT II videoacuity tester. The presence of fusion was examined by Worth 4-dot test(W4D). RESULTS: The mean value of near stereoacuity measured on Titmus and Randot was 45.6 and 29.1 seconds of arc(") respectively, in normal children, and 53.5 and 33.5" respectively, in(X)T children. The mean value of distance stereoacuity measured on the Binocular vision random dot E(BVRDE) and Binocular vision circle(BVC) was 131.3 and 46.1" respectively, in normal children, and 265.1 and 161.4" respectively, in(X)T children. There were significant differences in distance stereoacuity between normal and(X)T children(p0.05). In(X)T children, the mean value of stereoacuity for BVRDE and BVC was 155.7 and 70.4" in patients with fusion and 317.9" and 205.3" in those without. There were significant differences in distance stereoacuity for BVRDE and BVC between(X)T children with fusion and without fusion by W4D test(p<0.05). CONCLUSIONS: The result of this study aid in the evaluation of normative distance stereoacuity data in normal children and in the evaluation of control of the deviation and sensory function status by distance stereoacuity measurement in(X)T children aged 4-10 years.

Change of Postoperative Distance Stereoacuity in Intermittent Exotropic Patients

To determine whether distance stereoacuity improved following strabismus surgery in patients with intermittent exotropia, we tested distance stereoacuity of 107 patients preoperatively and postoperatively using the Mentor B-VAT IIVideo Acuity Tester. Following successful surgical alignment there was significant improvement of postoperative distance stereoacuity in binocular vision contour circles[BVC]and binocular vision random dot E[BVRDE]test[p<0.05 ]. Based on BVC testing, performance improved 45.8%of the patients after surgery, remained unchanged in 43.0%, and decreased in 11.2%. Based on BVRDE testing, performance improved 29.9%of the patients after surgery, remained unchanged in 66.4%, and decreased in 3.7%. But improvement of postoperative distance stereoacuity was not related statistically to age, operative methods, suppression, and preoperative size of deviation. From the results of this study, it is concluded that the BVC test is a useful test for assessing control in intermittent exotropic patients. Distance stereoacuity improved after successful operation, thus distance stereoacuity test may be helpful in evaluation of preoperative and postoperative intermittent exotropia control.