Double Maddox Rod Test Research Articles

Long-Term Surgical Outcomes of Bilateral Symmetrical Superior Oblique Nasal Tenotomy in Patients of Large A-Pattern Exotropia.

To report the long-term outcomes of bilateral symmetrical superior oblique (SO) nasal tenotomy in patients with large A-pattern exotropia (≥25 prism diopter [PD]). This retrospective study was conducted on 15 patients (aged: 4-28 years) of large A-pattern exotropia. An A-pattern was defined as >10 PD difference between up and down gaze at 6 m by use of the alternate prism cover test. Objective ocular torsion was assessed by fundus photography and subjective torsion by double Maddox rod test. All patients underwent horizontal muscle surgery according to the primary position horizontal deviation and bilateral symmetrical SO nasal tenotomy for A-pattern. Surgical success was defined as postoperative A-pattern of ≤10 PD, the absence of vertical and torsional diplopia, and the absence of V-pattern. The minimum follow-up period was 24 months. A total of 15 patients of large A-pattern exotropia (7 males and 8 females) with a mean age of 17.09 ± 7.9 years were included in the study. All patients had bilateral SO overaction of grade +3 or +4 with a mean preoperative A-pattern of 30.3 ± 3.9 PD. At 24 months of follow-up, esotropia in down gaze (V-pattern) was present in four patients with a mean of 11.25 ± 2.5 PD, (range, 10-15 PD). The rest of the 11 patients maintained successful alignment with a mean A-pattern of 3.18 ± 1.17 PD, (range, 2-5 PD). There was significant A-pattern collapse with a mean of 31 ± 9.1 PD after 2 years of follow-up, which was significantly associated with preoperative A-pattern (Pearson correlation, r = 0.7; t[15] = 4.0; P = 0.002). The mean of pre- and postoperative objective ocular torsion was found to be -0.5 ± 4° and -4.8 ± 3.8° with a mean extorsion effect of 4.67 ± 3.85°. There was a statistically significant difference between pre- and postoperative ocular torsion (°) (t [30] = 5.42; P < 0.001), the change in ocular torsion was significantly associated with preoperative torsion (Pearson correlation, r = 0.5; t [30] = 7.2; P < 0.001). None of the patients had subjective torsion on the double Maddox rod test pre- and postoperatively. Bilateral symmetrical SO nasal tenotomy is effective in cases with large A-pattern (>25 PD). The reduction of A-pattern and postoperative change in fundus torsion have a positive correlation with preoperative A-pattern and preoperative torsion, respectively.

A simple marking system for accurate intraoperative monitoring and adjustment of cyclotorsion strabismus surgery.

Ocular cyclotorsion is treatable only with surgery. The surgical procedure must be tailored individually to the specific etiologies causing the horizontal and vertical strabismus and its torsional components. An adjustable surgical approach is often used for postoperative or intraoperative adjustments. However, the methods currently used have some limitations. In this study, we propose a simple intraoperative marking system for all cyclotorsion correction surgery. The proposed marking system used three sets of surface markers: external horizontal markings, ocular horizontal markings, and surgical torsion markings, drawn in sequence. We retrospectively analyzed the surgical results using this novel marking system in this single-center, single-surgeon study. Fifteen patients with cyclotorsion who underwent treatment using the proposed marking system as an intraoperative aid between August 2019 and August 2021 were included. The medical charts were thoroughly reviewed, and the pre-and postoperative subjective and objective cyclotorsion were analyzed. Among the study subjects (10 males, 5 females; age range: 6-89 years), 13 had excyclotorsion and 2 incyclotorsion. Preoperative mean net subjective cyclotorsion measured by the double Maddox rod (DMR) test was 6.0° (standard deviation: 10.8°) and mean net disc-to-fovea angle (DFA) was 20.23° (13.21°). The postoperative net DMR and DFA were 0.2° (2.1°) and 14.09° (5.97°), respectively. The mean absolute net DMR and DFA being treated were 9.8° (4.8°) and 9.76° (4.61°). Overall, the proposed intraoperative marking system is a simple and quantitative method to assess, monitor, and adjust the torsional aspect for all strabismus surgeries.

Pearls & Oy-sters: Vertical Diplopia and Ocular Torsion: Peripheral vs Central Localization.

We describe a case with torsional deviation of the eyes from a brainstem lesion. Torsional eye movement refers to changes in the position of the eyes in the roll plane around the visual axis. When the head is tilted laterally (that is, rolled toward the shoulder), the eyes roll in the opposite direction as part of the torsional vestibulo-ocular reflex known as the ocular counter-roll. Pathologies that affect the otolith-ocular pathway can lead to a torsional deviation of the eyes as part of the ocular tilt reaction (OTR) that also causes vertical deviation of the eyes (skew deviation) and head tilt. Lesions caudal to the pontomedullary junction (such as the labyrinth, eighth cranial nerve, or vestibular nucleus) result in an OTR with ipsiversive torsional deviation, whereas lesions rostral to the junction result in an OTR with contraversive torsional deviation. Furthermore, torsional deviation of the eyes in the OTR is conjugate (incyclotorsion in the higher eye and excyclotorsion in the lower eye), whereas torsional deviation from ocular palsy in peripheral lesions is disconjugate (e.g., exyclotorsion only in the higher eye with superior oblique palsy). Therefore, the pattern of torsional eye deviation can be helpful in localizing the lesion. Several techniques including fundus photography, double Maddox rod testing, optical coherence tomography, and video-oculography are used to measure torsional eye position.

Clinical observation of anterior tucking of the superior oblique tendon for correction of excyclotropia in adults

Objective: To investigate the clinical effect of anterior 1/3 superior oblique tendon tucking in acquired symptomatic excyclotropia adults. Methods: Retrospective case series. Seven patients (7 eyes) with acquired symptomatic excyclotropia who underwent an anterior 1/3 superior oblique tendon tuck procedure in Tianjin Eye Hospital from January 2019 to December 2019 were included. There were 5 male patients and 2 female patients, with an average age of (49±12) years old. All the patients had a history of a closed head injury. There was torsional diplopia in primary position, and eye movement examination showed paralysis of the superior oblique muscle in the affected eye, without obvious hyperactivity of the inferior oblique muscle. The anterior 1/3 tendon of the superior oblique muscle was tucked during surgery according to the relaxation of the superior oblique tendon in the forced duction test. The paired-sample nonparametric rank sum test was used to analyze the preoperative and postoperative (at 1 day after surgery and the last follow-up) excyclotropia angle. Results: The mean tuck amount was (7.7±1.8) mm (range, 6.0 to 10.0 mm). During operation, patients complained that excyclotropia improved markedly. The excyclotropia angle with the double Maddox rod test improved significantly from preoperative 10° (8°, 15°) to 2° (0°, 3°) at 1 day (Z=-2.379; P<0.05) and 2° (2°, 5°) at the last follow-up (Z=-2.375; P<0.05). The follow-up period was (112+38) days. All patients had no complaints of excyclotropia at the last follow-up. Conclusions: The anterior 1/3 superior oblique tendon tucking can effectively improve clinical symptoms in the primary position in adults with acquired excyclotropia and diplopia. The short-term postoperative results seem to be stable, without significant regression. (Chin J Ophthalmol, 2021, 57: 685-688).

Surgical Outcomes of Nonadjustable Modified Harada-Ito Surgery.

PurposeThis study aimed to investigate the surgical outcomes of nonadjustable Harada-Ito surgery under general anesthesia.MethodsTwenty-two patients who underwent nonadjustable modified Harada-Ito surgery under general anesthesia were reviewed retrospectively. Among them, 21 out of the 22 patients who were followed up for 6 months after surgery were included in this study. Subjective cyclotorsion (double Maddox rod test) and objective cyclotorsions (fundus photography) were measured. Success of the surgery was defined as follows: success (the patients do not acknowledge diplopia at any direction), partial (the patients feel diplopia at a specific direction, but they do not feel discomfort in routine life), and fail (the patients feel diplopia in primary gaze, hence requiring a thorough investigation).ResultsThe mean age of the patients (18 male and 3 female) was 56.5 years (range, 40–77 years). Based on the alternate prism cover test, the patients had 4.2 ± 3.0 prism diopters of vertical deviation. The corrected amounts of cyclotorsion based on the double Maddox rod test and fundus photography were 14.8° ± 7.5° and 9.8° ± 7.9°, respectively, and were significantly different between the two methods (p = 0.006). After the surgery, 20 out of the 21 patients (95.2%) completely recovered from diplopia in the primary gaze. However, among the 20 patients, seven complained of diplopia in the secondary gaze (down gaze, four patients; head tilt gaze, three patients). The success group had a smaller preoperative subjective excyclotorsion than the partial and fail groups (12.6° ± 2.5° and 21.0° ± 8.9°, respectively; p = 0.046).ConclusionsNonadjustable modified Harada-Ito surgery under general anesthesia has favorable success rate, and preoperative subjective excyclotorsion can be a prognostic factor in patients with bilateral superior oblique palsy.

The use of OCT in the assessment of ocular torsion

Measurement of ocular torsion is an essential part of evaluation, differential diagnosis and management of patients with strabismus. Conventionally, double Maddox rod testing (DMRT) and dilated fundus photography are used to measure ocular torsion. DMRT depends upon reliable patient response. Fundus photography requires dilation and analysis. Heidelberg ocular coherence tomography (OCT) provides an assessment of torsion as a disk-foveal angle (DFA) easily obtained without dilation, but this has not been clinically validated. We studied the correlation between DMRT, fundus photography, and OCT methods of measuring torsion.

Differentiating Acute and Subacute Vertical Strabismus Using Different Head Positions During the Upright-Supine Test

Accurate clinical differentiation between skew deviation and fourth nerve palsy (4NP) is critical in the acute and subacute settings. To determine the sensitivity and specificity of the upright-supine test to detect vertical misalignment changes using different head positions for the diagnosis of acute or subacute skew deviation vs 4NP. This multicenter study enrolled consecutive patients from Coimbra University Hospital Centre, Coimbra, Portugal, and Michigan State University, Lansing, within 2 months of presenting with vertical diplopia and diagnosed as having skew deviation or acquired unilateral 4NP. The study used nonmasked screening and diagnostic test results from June 1, 2013, to December 31, 2016. Data were analyzed from January 1, 2017, to June 30, 2017. A 50% or greater change in vertical misalignment between the upright and supine positions, with the head centered and tilted to either side. Measurements included the alternate prism and cover (APC) test, the double Maddox rod test, the APC test change index ([measurement upright - measurement supine] / [measurement upright + measurement supine]), and the APC test sensitivity and specificity. Of the 37 included patients, the mean (SD) age was 58 (14) years, and 26 (70%) were male. We enrolled 19 patients (51%) with skew deviation and 18 (49%) with 4NP. Eighteen patients with skew deviation (95%) showed additional ocular motor and/or neurological signs. When moving to the supine position, only 1 patient with skew deviation (5%) showed more than a 50% decrease of hypertropia with the head centered (APC test: sensitivity, 5%; specificity, 100%). Three patients with 4NP (17%) showed more than a 50% decrease of hypertropia with the head tilted toward the hypertropic eye, and 10 patients with 4NP (56%) showed more than a 50% increase of hypertropia with the head tilted toward the hypotropic eye. Change indexes were different between the skew deviation and 4NP groups for head tilt to the hypotropic eye (difference, -0.33 prism diopters; 95% CI, -0.43 to -0.20; P < .001). Cyclotorsion worsened in the supine position only in patients with skew deviation (hypertropic eye: difference, -7.6 prism diopters; 95% CI, -13.00 to -0.75; P = .01; hypotropic eye: difference, 8.2 prism diopters; 95% CI, 0 to 15.75; P = .03). The upright-supine test with the head centered is not a sensitive method to separate acute or subacute skew deviation from 4NP. Conversion of an incomitant vertical deviation in the upright position to a comitant vertical strabismus in the supine position in all head positions, as well as the absence of additional ocular motor and/or neurologic signs, may constitute a more useful clue.

Test-retest variability of cyclodeviations measured using the double Maddox rod test

The double Maddox rod test is often used to measure cyclodeviations and to monitor change over time. The purpose of this study was to estimate test-retest reliability and the amount of cyclodeviation that would be considered real change using 95% limits of agreement. We retrospectively studied 86 clinically stable patients with double Maddox rod measurements 5-175days apart (median, 69days). The range of cyclodeviation at the first measurement was 6° incyclodeviation to 15° excyclodeviation. We calculated the half width of the 95% limits of agreement to be 4.7°, which means that a change of ≥5° in cyclodeviation would be considered a real change. The threshold of 5° should be used when assessing change between two measurements made with double Maddox rods.

Development of a simple computerized torsion test to quantify subjective ocular torsion.

PurposeThe double Maddox-rod test (DMRT) and Lancaster red-green test (LRGT) are the most widely used tests worldwide to assess subjective ocular torsion. However, these tests require equipment and the quantified results of ocular torsion are only provided in rough values. Here we developed a novel computerized torsion test (CTT) for individual assessment of subjective ocular torsion and validated the reliability and accuracy of the test compared with those of the DMRT and LRGT.MethodsA total of 30 patients with cyclovertical strabismus and 30 controls were recruited. The CTT was designed using Microsoft Office PowerPoint. Subjects wore red-green filter spectacles and viewed gradually tilted red and cyan lines on an LCD monitor and pressed the keyboard to go through the slides, until both lines seemed parallel. All subjects underwent the CTT, DMRT, and LRGT. Intraclass correlation coefficients and Bland-Altman plots were analyzed to assess the acceptability of the CTT compared with that of the DMRT.ResultsBoth the DMRT and CTT showed no significant test-retest differences in the strabismus and control groups. The DMRT and CTT results demonstrated an acceptable agreement. The reliability of the CTT was better than that of the DMRT. The LRGT showed low sensitivity for the detection of ocular torsion compared with the DMRT (40.0%) and CTT (39.1%).ConclusionOur results suggest that the assessment of subjective ocular torsion using the CTT based on PowerPoint software is simple, reproducible, and accurate and can be applied in clinical practice.

Comparison of Double Maddox Rod Test and Bagolini Striated Lens Test for Superior Oblique Palsy

Comparison of Double Maddox Rod Test and Bagolini Striated Lens Test for Superior Oblique Palsy

Unmasking Bilateral Inferior Rectus Restriction in Thyroid Eye Disease: Using Degree of Cyclotropia

PurposeThyroid eye disease (TED) frequently causes strabismus and diplopia. Though the condition involves multiple extraocular muscles in both eyes, the inferior rectus (IR) muscle is particularly susceptible. TED may be so asymmetric as to mask the involvement of the contralateral IR. The purpose of this study was to determine if the degree of preoperative cyclotropia measured with an objective test could be used to predict the extent of bilateral IR disease and assist in surgical planning.MethodsAdults with TED involving the IR and demonstrating cyclotropia were enrolled. Preoperative and postoperative sensorimotor exam included quantification of cyclotropia using double Maddox rod test (DMR). Forced ductions were done intraoperatively. Degree of cyclotropia was compared to results of duction tests and surgical outcome.ResultsTwelve participating patients demonstrated excyclotropia on DMR test preoperatively (mean 16 ± 9°). Unilateral IR recession was planned based on the results of preoperative ocular rotations and forced duction testing in eight cases. The remaining four underwent bilateral IR recession. Four of the unilateral recession cases presented with reversal of the hypotropia, obvious limitation of elevation in the unoperated eye, and persistent symptomatic excyclotropia at the first postoperative visit. The mean excyclotropia of the bilateral cases was 21 ± 5°, compared to 5.5 ± 3° in the unilateral group (P < 0.005).ConclusionsPrism diopters of hypotropia, limitation of elevation, and forced duction testing evaluate muscle function relative to its yoke and may underestimate contralateral IR involvement in the case of asymmetrical disease. Duction testing and forced ductions are qualitative and subjective. Results suggest that degree of excyclotropia correlates well with severity of IR restriction, and that amounts exceeding 15° infer bilateral IR involvement.

Measurement of Ocular Cyclotorsion in Superior Oblique Palsy Using a Single Maddox Rod

To describe a modified technique to measure ocular cyclotorsion using only 1 Maddox rod and compare it with the traditional double Maddox rod test (DMR). Ocular cyclotorsion was prospectively measured in 48 consecutive patients with superior oblique palsy. Four measurements were taken; 2 using 2 Maddox rods: (A) a red rod in front of the affected eye and a white rod in front of the fellow eye and (B) red rod in front of the sound eye and red in front of the affected eye. Two additional sets of measurements were taken using 1 red Maddox rod in front of 1 eye only, where horizontal lines in the room served as a reference: (C) the red rod in front of the affected eye and (D) the red rod in front of the sound eye. Mean ocular cyclotorsion in 48 patients was 6.7°, 6.8°, 6.6°, and 6.1° in measures A, B, C, and D, respectively. The agreement between A and C did not differ statistically, whereas the agreement between B and D was statistically different (P < 0.0001). There was high repeatability in both comparisons. Ocular cyclotorsion may be measured using a single Maddox rod instead of two. It is simpler to conduct than the DMR.

Accuracy of Double Maddox Rod with Induced Hypertropia in Normal Subjects

Background and PurposeThe double Maddox rod is a commonly used instrument to test for cyclotorsion in the clinical setting. This paper assesses the ability of patients without torsional complaint to accurately demonstrate torsional status with varying degrees of induced hypertropia as tested by double Maddox rod.MethodsThirty-seven orthophoric subjects underwent double Maddox rod testing with vertical prism of 3Δ, 10Δ, 16Δ, 20Δ, and 30Δ. Subjective torsion was recorded for each prism diopter.ResultsMean subjective torsion was recorded as 0.95°, 1.6°, 1.9°, 2.1°, and 2.2° for 3Δ, 10Δ, 16Δ, 20Δ, and 30Δ, respectively. Torsion increased in a logarithmic manner as modeled by R™ software version 2.15.2.ConclusionsThe double Maddox rod test as commonly used in clinical practice is both subjective and prone to administrator and subject error. Subjects have more difficulty properly aligning the double Maddox rod as distance between images is increased. It is also possible that recruitment of the oblique muscles during attempted vertical fusion leads to subjective torsion during double Maddox rod testing in otherwise normal participants.

Relationship of Hypertropia and Excyclotorsion in Superior Oblique Palsy

PurposeTo evaluate the correlation between hypertropia and excyclotorsion in acquired superior oblique palsy (SOP).MethodsThirty-one patients with acquired unilateral SOP were recruited for this study. The torsional angle of each patient was assessed via one objective method (fundus photography) and two subjective methods (double Maddox rod test and major amblyoscope). The patient population was divided into two groups (concordance group, n = 19 and discordance group, n = 12) according to the correspondence between the hypertropic eye (paralytic eye) and the more extorted eye (non-fixating eye), which was evaluated by fundus photography.ResultsThe mean value of objective torsion was 5.09° ± 3.84°. The subjective excyclotorsion degrees were 5.18° ± 4.11° and 3.65° ± 1.93° as measured by double Maddox rod test and major amblyoscope, respectively. Hypertropia and the excyclotorsional angle did not differ significantly between the groups (p = 0.257). Although no correlation was found in the discordance group, the concordance group showed a significant and positive correlation between hypertropia and excyclotorsion (p = 0.011).ConclusionsTorsional deviation was not related to hypertropia. However, in the concordance patients in whom the hypertropic eye showed excyclotorsion, a significant positive correlation was found between hypertropia and excyclotorsion.

Comparison of subjective and objective torsion in patients with acquired unilateral superior oblique muscle palsy

BackgroundTo compare objective torsion, measured using fundus photography, and subjective torsion, measured with the Lancaster red-green test (LRGT) or double Maddox rod test (DMRT), in patients with acquired unilateral superior...

Torsional Diplopia after Orbital Decompression and Strabismus Surgery

To investigate diplopia after orbital decompression in patients with thyroid-related orbitopathy. We retrospectively analyzed medical records of 45 consecutive patients who had undergone orbital decompression surgery (DS) and a subgroup of 10/45 patients who underwent disinsertion of the inferior oblique (IO) muscle during DS. Diplopia was assessed before DS and 1 and 3 months after DS. Residual strabismus defects were treated surgically approximately 3 months after DS with follow-up visits 1 week, 3 months, and 6 months postoperatively. Patients with horizontal or vertical diplopia were evaluated using the alternate prism-and-cover test and torsional diplopia (TD) using a double Maddox rod test to quantitate their strabismus. Strabismus surgery was effective in treating the horizontal and vertical diplopia (13/40 cases with residual deviations required prism glasses), but did not resolve the TD. None of the patients with IO disinsertion during DS complained of TD before strabismus surgery. However, after strabismus surgery, TD occurred in all 10 patients with IO disinsertion vs 8/30 patients without IO disinsertion (p<0.001, Fisher exact test). Overall, TD was induced in 18/45 (40%) of the DS cohort. Patients with IO disinsertion during DS may be at increased risk of developing TD postoperatively. We recommend sparing or reattaching the IO muscle during DS when possible to reduce the risk of developing untreatable TD.

Intraoperative Adjustable Suture Surgery for Excyclotorsion: A Modification of the Harada-Ito Procedure

This study evaluated the surgical results of intraoperative adjustable tucking of the anterior portion of the superior oblique tendon for treatment of excyclotorsion. Two cases of acquired bilateral superior oblique palsy with symptomatic excyclotorsion and minimal vertical deviation in primary position were considered. Tucking of the anterior one-third of the superior oblique tendon was performed with a nonabsorbable suture. The amount of tuck was adjusted until the fovea was at the level of the superior one-third of the disc through indirect ophthalmoscopy. In the patient with local anesthesia, a double Maddox rod test was used to evaluate subjective cyclotorsion intraoperatively. After surgery, the patients became symptom-free. No regression toward excyclotorsion was noted during 18 months of follow-up. Tucking of the anterior portion of the superior oblique tendon is an effective procedure for improving symptomatic excyclotorsion in patients with bilateral superior oblique palsy without significant vertical deviation in primary position.

Clinico-Radiologic Findings of Entrapped Inferior Oblique Muscle in a Fracture of the Orbital Floor

A 51-year old man presented with vertical and torsional diplopia after reduction of a blowout fracture at another hospital one year ago. He had no anormalies of head position and 14 prism diopters (PD) right hypertropia (RHT) in the primary position. In upgaze no vertical deviation was found, and hyperdeviation on downgaze was 35PD. Bielschowsky head tilt test showed a negative response. Distinct superior oblique (SO) and inferior rectus (IR) underaction of the right eye was noted but IO overaction was mild on the ocular version test. Double Maddox rod test (DMRT) revealed 10-degree extorsion, but fundus extorsion was minimal in the right eye.Thin-section coronal CT scan showed that there was no fracture line on the anterior orbital floor, but a fracture remained on the posterior orbital floor. Also, the anterior part of the right inferior oblique muscle was vertically reoriented and the medial portion of the inferior oblique muscle was not traced on the coronal CT scan. The patient underwent 14 mm right IO recession and 3 mm right IR resection. One month after the surgery, his vertical and torsional diplopia were eliminated in the primary position.

Diagrammatic presentation of the results of strabismus examination in the various diagnostic positions of gaze need standardization

We have found that there is no consistent opinion about the recording of the results of ocular deviations in various diagnostic positions of gaze, as well as for head tilt tests to the right and to the left in textbooks, manuscript and hospital medical records in China. For the sake of convenience in analysis and diagnosis of ocular deviations, it is necessary to have a unified opinion in recording these results. In accordance with the habitual diagrammatic presentation of the results of ocular deviations in the various diagnostic positions of gaze, as well as for head tilt tests to the right and to the left at home and abroad, we recommend two recording methods: the examiner's view and the patient's view. The patient's view is used in the synoptophore readings, Worth four-dot test, Maddox rod and double Maddox rod test, diplopia test, Hess screen and Lancaster screen test. The examiner's view is used in the prism cover test and arrangement for pictures in nine ocular positions of gaze.

Effect of Posterior Tenectomy of the Superior Oblique on Objective and Subjective Torsion in Cases of Superior Oblique Overaction

To evaluate the effect of posterior tenectomy of the superior oblique on the correction of A-pattern, superior oblique overaction and the changes in torsion that occur in such cases. This prospective study included 15 consecutive cases of bilateral superior oblique overaction with an A-pattern of more than 20 PD, a difference of deviation between 25 degrees up-gaze and 35 degrees downgaze, and superior oblique overaction of 2+ to 3+ on a scale of 0 to 4+. Deviation was measured in the primary position, 25 degrees upgaze, and 35 degrees downgaze using the prism bar cover test, and torsion was measured using a synoptophore, the double Maddox rod test, and fundus photographs. Measurements were obtained preoperatively and postoperatively at 1 week, 1 month, and 3 months. All case-patients underwent a standard temporal route posterior tenectomy of the superior oblique by a single surgeon. Mean age was 11.2 +/- 4.2 years with 14 cases of A-pattern exotropia. Mean superior oblique overaction was 2.60 +/- 0.50 in the right eye and 2.26 +/- 0.45 in the left eye, which decreased postoperatively to 2.20 +/- 0.56 and 1.80 +/- 0.41, respectively. The index of surgical effect was 0.84 in the right eye and 0.79 in the left eye. Postoperatively, mean correction of the A-pattern was 17.53 +/- 5.82 PD (index of surgical effect, 0.7). Subjective measurement of torsion was more consistent with the synoptophore compared with the double Maddox rod test. Objective measurement of torsion (fundus photography) was higher compared with subjective measurement. Postoperatively, there was insignificant change in the amount of torsion in upgaze and primary position. Posterior tenectomy of the superior oblique results in significant and controlled weakening of the superior oblique and collapse of the A-pattern with a clinically insignificant change in the amount of torsion.