A binocular iPad treatment for amblyopic children.

PURPOSE: Monocular amblyopia treatment (patching or penalization) does not always result in 6/6 vision and amblyopia often recurs. As amblyopia arises from abnormal binocular visual experience, we evaluated the effectiveness of a novel home-based binocular amblyopia treatment. METHODS: Children (4-12 y) wore anaglyphic glasses to play binocular games on an iPad platform for 4 h/w for 4 weeks. The first 25 children were assigned to sham games and then 50 children to binocular games. Children in the binocular group had the option of participating for an additional 4 weeks. Compliance was monitored with calendars and tracking fellow eye contrast settings. About half of the children in each group were also treated with patching at a different time of day. Best-corrected visual acuity, suppression, and stereoacuity were measured at baseline, at the 4- and 8-week outcome visits, and 3 months after cessation of treatment. RESULTS: Mean (±SE) visual acuity improved in the binocular group from 0.47±0.03 logMAR at baseline to 0.39±0.03 logMAR at 4 weeks (P<0.001); there was no significant change for the sham group. The effect of binocular games on visual acuity did not differ for children who were patched vs those who were not. The median stereoacuity remained unchanged in both groups. An additional 4 weeks of treatment did not yield additional visual acuity improvement. Visual acuity improvements were maintained for 3 months after the cessation of treatment. CONCLUSIONS: Binocular iPad treatment rapidly improved visual acuity, and visual acuity was stable for at least 3 months following the cessation of treatment.

Longitudinal changes in refractive error of children with infantile esotropia.

AIM: the aim of this study was to quantify changes in refractive status over time in children with infantile esotropia (ET) and to analyse a number of clinical factors associated with infantile ET to determine how they may affect emmetropisation. METHODS: longitudinal cycloplegic refraction data were collected for 5-12 years from 143 consecutive children enroled in a prospective study of infantile ET by 6 months of age. Changes in refractive error with age were summarised with descriptive statistics and the influence of amblyopia, undercorrection of hypermetropia, accommodation, and binocular factors on emmetropisation were evaluated by analysis of variance and t-tests. RESULTS: most had low to moderate hypermetropia on the initial visit (55% had <+3.00 D). Although the initial refractive error is similar to normative data, the rapid decrease in hypermetropia that characterises normal development during the first 9 months of life is absent in children with infantile ET. After 9 months of age, children with infantile ET follow a developmental course, which is similar to the normative course; there is little change in hypermetropia during years 1-7, followed by a decline of approximately -0.5 D/year beginning at age 8 years. None of the clinical factors examined had a statistically significant effect on the course of refractive changes with age. CONCLUSION: children with infantile ET exhibit a different pattern of refractive development than that seen in normative cohorts. The long-term changes in refraction observed in children with infantile ET suggest that there is a need for long-term clinical follow-up of these children.

Re-recession of the medial rectus muscles in patients with recurrent esotropia.

PURPOSE: Retrospective evaluation of changes in ocular motility after surgical re-recession of the medial rectus (MR) muscles as treatment of recurrent esotropia (ET). METHODS: We describe 115 patients (age, 11 months-77 years; median, 11.1 years; 83 children and 32 adults) with an average amount of non-accommodative ET before surgery of 18.7 PD (SD = 8.8 PD). Preoperative alignment, amount of re-recession, distance from insertion to the limbus, and postoperative alignment and versions were collected. RESULTS: In most cases, MR muscles were re-recessed to a fixed distance of 12 mm from the limbus, with unilateral re-recessions in cases with relatively small ET (typically < 20 PD) and bilateral re-recessions in cases with larger amounts of ET (typically > 20 PD). No clear relation was found between the amount of re-recession and the change in alignment in prism diopters. The success rate (esotropia [ET] < or = 10 PD or exotropia [XT] < or = 8 PD) 4 weeks to 8 months after surgery was 85%, with 4 patients still showing ET and 13 patients showing XT. Incidence of XT was higher for bilateral than for unilateral re- recessions. Significant underaction of the MR muscles was noted in 7% of the patients. None of the undercorrected patients and only 1 of the overcorrected patients were adults. Among adults, incidence of MR underaction was 4%. Long-term follow-up (8-120 months; median, 25 months) data from 59 patients indicated that good stability in alignment can be expected. CONCLUSION: The results support the notion that MR re-recession to 12 mm from the limbus successfully corrects recurrent ET up to 35 PD and that it is particularly effective in adults.

Costenbader lecture. Anatomy and surgery of the inferior oblique muscle: recent findings.

BACKGROUND: Surgery of the inferior oblique muscle (IO) has undergone significant changes in the past 160 years. Many investigators have contributed to our understanding of the action of this muscle and to the surgical options that have developed. This article reviews the history of IO surgery with particular emphasis on the anterior transposition procedure. METHODS: Anatomic and physiologic studies on the neurofibrovascular bundle of the IO are presented. RESULTS: The ligamentous structure of the neurofibrovascular bundle of the IO provides the ancillary origin for the posterior temporal fibers of the IO when its insertion is transposed anteriorly. DISCUSSION: Recent anatomic findings have helped explain the effects of the anterior transposition procedure and allow further development of our surgical armamentarium for vertical strabismus problems. Further nasal transposition of that insertion should reduce or eliminate the incidence of the antielevation syndrome. If transposed far nasally, the IO could convert to an intorter, as well as to an antielevator and tonic depressor.

Early binocular visual experience may improve binocular sensory outcomes in children after surgery for congenital unilateral cataract.

PURPOSE: To compare the effect of intensive and reduced occlusion therapy regimens on binocular sensory outcomes, visual acuity, and the prevalence of strabismus in children after surgery for congenital unilateral cataract. METHODS: Two nonrandomized groups of patients were studied prospectively: (1) an intensive occlusion group (n = 29) patched 80% of waking hours were followed for a median 6.9 years and (2) a reduced occlusion group (n = 8) patched 25% to 50% of waking hours were followed for a median 4.3 years. Six subjects in the intensive group and 4 in the reduced occlusion group had secondary intraocular lenses. Two subjects in the intensive group had epikeratophakia surgery. Binocular sensory function was assessed with random dot and contour stereoacuity tests and the Worth 4-dot test. The prevalence and age at onset of strabismus were determined from the patients' charts. RESULTS: A higher proportion of subjects in the reduced occlusion group (50%) had stereoacuity or fusion compared with the intensive occlusion group (14%), a borderline significant difference (P =.08). No significant difference (P =.55) was found in median visual acuity between the intensive (20/50) and the reduced occlusion (20/55) groups. The 90% prevalence of strabismus in the intensive occlusion group was slightly higher than the 63% prevalence in the reduced occlusion group, although this difference was not significant (P =.18). CONCLUSIONS: These results suggest that a reduced occlusion protocol may be associated with better binocular sensory outcomes and a reduced prevalence of strabismus without compromising good visual acuity in children treated for congenital unilateral cataract.

Anterior and nasal transposition of the inferior oblique muscle: a preliminary case report on a new procedure.

PURPOSE: To describe this new extraocular muscle surgery. METHOD: Case Report of a child in need of treatment of a weak superior oblique muscle which, at surgery, was in fact found to be absent. After a prior only partially successful recession of the antagonist inferior oblique (IO), the IO muscle was detached and transposed to a new insertion in the inferior nasal quadrant converting the muscle, as a result of its functional origin being the neurovascular bundle ["Ligament of Stager"-ed], from an extorter and elevator of the globe to an intorter and depressor. RESULT: Satisfactory binocular alignment was achieved. CONCLUSION: This new surgical procedure provides significant advantages, and should be added to our surgical armamentarium.

Surgical management of V-pattern strabismus and oblique dysfunction in craniofacial dysostosis.

INTRODUCTION: Strabismus affects as many as 60% to 70% of patients with craniofacial dysostosis. V-pattern strabismus with severe oblique muscle dysfunction is the most common ocular motility problem seen and can be difficult to manage. Few studies have reported on the results of strabismus surgery in this condition. METHODS: We retrospectively reviewed the surgical management and outcomes of 14 patients with craniofacial dysostosis who underwent 16 operations to determine the optimal surgical procedure and to report on extraocular muscle anomalies noted at the time of surgery. Operations performed included medial rectus muscle infraplacement (n = 2), inferior oblique (IO) recession (n = 3), IO myectomy (n = 3), IO anterior transposition (n = 3), and IO denervation/extirpation (n = 5). RESULTS: All patients had significant residual ocular motility dysfunction postoperatively. No beneficial effect was noted after IO anterior transposition or after medial rectus muscle infraplacement. Modest improvement of the V-pattern and oblique muscle dysfunction was noted after denervation/extirpation and myectomy of the IO muscle. Bilateral absent or anomalous superior oblique tendons were noted in 8 of 9 patients in whom the superior oblique tendon was examined at surgery. CONCLUSIONS: Strabismus in craniofacial dysostosis is complex and difficult to cure with surgery. Denervation/extirpation and myectomy of the IO muscle offered modest benefits, though neither procedure resulted in normalization of ocular motility. Agenesis of the superior oblique tendon may be causally related in a large proportion of affected patients.

Screening for amblyopia in preverbal children with photoscreening photographs: II. Sensitivity and specificity of the MTI photoscreener.

OBJECTIVE: To determine the sensitivity and specificity of vision screening using the Medical Technology and Innovations (MTI), Inc., PhotoScreener. DESIGN: Cross-sectional study. PARTICIPANTS AND TESTING: Three hundred ninety-two children less than 4 years of age received a complete ophthalmologic examination and were photographed using the MTI PhotoScreener. One hundred three children had normal examinations, and the remaining 284 children had conditions of interest for pediatric screening: ptosis, media opacity, refractive error, or strabismus. Five children were excluded. MAIN OUTCOME MEASURES: The grading of the photographs by the manufacturer's representative was compared with the results of the ophthalmologic examinations. Sensitivity and specificity of vision screening were determined. RESULTS: The analysis of all informative photographs resulted in a sensitivity of 65% and a specificity of 87%. The sensitivity of detection for children with some forms of strabismus was high, up to 95% for esotropia of 10Delta or more. Sensitivities for the detection of ptosis, media opacity, and refractive error were poor in patients where strabismus was not also present. CONCLUSIONS: The MTI PhotoScreener may play a role in preverbal vision screening; identification of two of three children with amblyopiogenic factors before age 4 would be an exciting advance in public health. However, improvement in the ability to identify children with media opacity and refractive error is necessary. Improvements may be possible with modifications of the examination failure and photograph grading criteria.

Screening for amblyopia in preverbal children with photoscreening photographs. III. improved grading criteria for hyperopia.

OBJECTIVE: To examine the ability of the Medical Technology and Innovations (MTI), Inc., Photoscreener (Cedar Falls, IA) to detect hyperopia and to improve the photograph grading criteria to screen for amblyopiogenic levels of hyperopia. DESIGN: Cross-sectional study and reanalysis. PARTICIPANTS AND TESTING: In previous work, 392 participants received a complete ophthalmologic examination and were photographed using the MTI Photoscreener. For this study, all 209 participants with normal examination findings (65 children) or hyperopia without anisometropia (144 children) were selected. The data were reanalyzed using modified photograph grading and ophthalmologic examination failure criteria. Potential reasons for why many children with hyperopia passed photoscreening were explored. MAIN OUTCOME MEASURES: We determined whether a study participant would pass or fail screening with a given photograph grading and ophthalmologic examination failure criteria. RESULTS: Most children with hyperopia of +2.00 to +3.50 diopters (D) passed screening with the MTI instrument, in most cases because their photographs lacked bright crescents. When bright crescents in at least two of the four possible meridians were the grading guideline for screening failure and the pediatric ophthalmologists' consensus hyperopia failure criteria (> +3.50 D) were adopted, the sensitivity for hyperopia detection was 100% and the specificity was 88%. Identical results were obtained using the American Academy of Ophthalmology Preferred Practice Pattern hyperopia failure criteria (>/= +4.50 D). CONCLUSIONS: The MTI photograph grading guidelines can be simplified, and the ophthalmologic examination failure criteria for hyperopia can be improved. The presence of a bright crescent in the lower or the left pupillary margin indicate hyperopia in an amblyopiogenic range (> +3.50 D).

Why does early surgical alignment improve stereoacuity outcomes in infantile esotropia?

PURPOSE: Recent studies of infantile esotropia suggest that early surgical alignment may enhance stereopsis and that alignment during the first 6 months of life may be optimal. Early surgery both establishes alignment during an early critical period for the development of stereopsis and minimizes the duration of misalignment. Here we examine the role of these 2 factors in promoting improved stereopsis outcomes. METHODS: Participants were 129 consecutive patients enrolled in a prospective study of infantile esotropia who were followed up for a minimum of 5 years. At ages 5 to 9 years, Randot stereopsis was evaluated. RESULTS: Multiple linear regression indicated that duration of misalignment, but not age at alignment or age at onset, was a significant factor in determining random dot stereopsis outcomes. Moreover, patients with stereopsis were less likely to have a loss of horizontal eye alignment requiring surgery than patients without stereopsis (14% versus 32%; z = 1.96, P =.05). Patients with stereopsis were also less likely to have dissociated vertical deviation than patients without stereopsis (25% versus 63%; z = 3.36, P <.001). CONCLUSIONS: The results suggest that early surgical alignment is associated with better stereopsis in those patients with infantile esotropia who were treated during the first 24 months of life, because early surgery minimizes the duration of misalignment, not because alignment is achieved during an early critical period of visual maturation. Random dot stereopsis can also be achieved in patients with alignment provided that the duration of misalignment is not prolonged. Improved outcomes of random dot stereopsis are associated with more stable long-term alignment outcomes.

Long-term results of silicone expander for moderate and severe Brown syndrome (Brown syndrome "plus").

BACKGROUND: The treatment of Brown syndrome has been undergoing an evolution toward more effective procedures with fewer operative interventions. Dr Kenneth Wright has introduced a procedure of superior oblique muscle tenotomy with a silicone expander to reduce the incidence of overcorrection. METHODS: There was a retrospective study of 20 eyes of 19 consecutive patients with moderate or severe Brown syndrome (Brown syndrome "plus"). Follow-up ranged from 12 to 72 months. The expander, which varies 6 to 10 mm in length, was placed in all patients in the tenotomized superior oblique muscle tendon 5 mm nasal to the nasal border of the superior rectus muscle using 7-0 or 8-0 Prolene suture without violating the inner layer of the intermuscular septum. The intermuscular septum was closed over the silicone expander. RESULTS: One hundred percent of patients had resolution of the down shoot in adduction and some or full ability to elevate the eye in adduction. Twenty percent of patients required reoperation (12.5% using 5-8 mm expanders) for overcorrection. Restriction of downgaze was not seen postoperatively. Patients often show an undercorrection 1 to 6 months postoperatively and improve or occasionally overcorrect at 1 to 2 years postoperatively. One patient with a 10-mm expander extruded the implant. DISCUSSION: Placement of a 5- to 8-mm silicone expander in the tenotomized superior oblique muscle tendon is an effective means of correcting Brown syndrome with a low rate of reoperation. Initial undercorrection should not discourage the surgeon because improvement may continue for up to 3 years. The goal of treatment should be to convert a moderate or severe Brown syndrome (Brown syndrome plus) to a mild Brown syndrome ("true" Brown syndrome). CONCLUSION: This technique reduces the need for either simultaneous or subsequent inferior oblique muscle weakening and represents an advance in the treatment of Brown syndrome.

A value analysis model applied to the management of amblyopia.

PURPOSE: To assess the value of amblyopia-related services by utilizing a health value model (HVM). Cost and quality criteria are evaluated in accordance with the interests of patients, physicians, and purchasers. METHODS: We applied an HVM to a hypothetical statistical ("median") child with amblyopia whose visual acuity is 20/80 and to a group of children with amblyopia who are managed by our practice. We applied the model to calculate the value of these services by evaluating the responses of patients and physicians and relating these responses to clinical outcomes. RESULTS: The consensus value of care for the hypothetical median child was calculated to be 0.406 (of 1.000). For those children managed in our practice, the calculated value is 0.682. Clinically, 79% achieved 20/40 or better visual acuity, and the mean final visual acuity was 0.2 logMAR (20/32). Value appraisals revealed significant concerns about the financial aspects of amblyopia-related services, particularly among physicians. Patients rated services more positively than did physicians. CONCLUSIONS: Amblyopia care is difficult, sustained, and important work that requires substantial sensitivity to and support of children and families. Compliance and early detection are essential to success. The value of amblyopia services is rated significantly higher by patients than by physicians. Relative to the measured value, amblyopia care is undercompensated. The HVM is useful to appraise clinical service delivery and its variation. The costs of failure and the benefits of success are high; high-value amblyopia care yields substantial dividends and should be commensurately compensated in the marketplace.

Screening for amblyopia in preverbal children with photoscreening photographs. National Children's Eye Care Foundation Vision Screening Study Group.

OBJECTIVE: This study aimed to determine the ability of healthcare professionals and lay volunteers to grade photoscreening photographs. DESIGN: The study design was a cross-sectional study. PARTICIPANTS AND INTERVENTION: One hundred children 3 years of age or younger received a complete ophthalmologic examination and were photographed using the Medical Technology Innovations (MTI) photoscreener. Twenty-six children had normal examination results, and the remaining 74 children had conditions that are of interest for pediatric screening, including strabismus, refractive error, media opacities, and ptosis. Eighteen volunteers, including pediatric ophthalmologists, pediatricians, ophthalmic technicians, health department nurses, Prevention of Blindness Society personnel, and Lions Club volunteers, graded each of the 100 photoscreening photographs. MAIN OUTCOME MEASURES: Sensitivity and specificity of vision screening and of photograph grading were measured. RESULTS: Results from various graders yielded sensitivities ranging from 37% to 88% and specificities ranging from 40% to 88%. No single grader achieved sensitivity and specificity both greater than 70%. The grading of the manufacturer's representative had a sensitivity of 43% and a specificity of 85%. Sensitivity decreased to 31% for strabismus and 18% for refractive error when the correct type of strabismus or refractive error was required to be considered true-positives. Results were not positively correlated with the ophthalmologic knowledge of the participant. CONCLUSIONS: The wide variability in sensitivities and specificities among graders indicates inconsistent photograph interpretation skills or deficient screening guidelines or both. For off-axis photoscreening as implemented by the MTI system to become a useful vision-screening method, additional photograph interpretation skill transfer may be beneficial, although not necessarily sufficient.

Stiffness of the inferior oblique neurofibrovascular bundle.

PURPOSE: To assess the mechanical ability of the inferior oblique neurofibrovascular bundle (NFVB) to act as an ancillary origin for the inferior oblique muscle after anterior transposition. METHODS: Stress-strain relations and Young's modulus of elasticity, a measure of tissue stiffness, were determined for the NFVB in vitro, in situ, and in vivo in dynamic and static conditions. For comparison, similar studies were performed in vitro on the superior oblique tendon (SOT). RESULTS: Young's moduli for NFVB in situ (6.3 MPa [megapascals]) and in vivo (11.8 MPa) were approximately 2 and 4 times greater (P < 0.05), respectively, than those of isolated NFVB in vitro at 5% to 10% dynamic strain (3 MPa). In dynamic conditions, Young's moduli in vitro for the NFVB and the SOT were similar. CONCLUSIONS: The NFVB is a biomaterial that has stiffness properties similar to the SOT. Within the range of forces typical of normal eye movements (79 to 393 mN), the NFVB alone can tolerate forces of 98 mN at 0% to 10% strain and 393 mN at 15% to 20% strain, based on dynamic in vitro analysis. The greater measured stiffness in situ and in vivo suggest that the NFVB in the intact orbit potentially has a resting strain of 15% to 20%, and additional tissues in parallel with the NFVB also contribute to total stiffness. These data support the hypothesis that the NFVB, acting alone or in concert with adjacent orbital tissues, may form an ancillary origin for the inferior oblique muscle after anterior transposition.

A comparative microscopic analysis of the capsule of the nerve to the inferior oblique muscle.

PURPOSE: To delineate the nature of the nerve capsule to the inferior oblique muscle at birth and adulthood, and to compare it to the nerve capsules of other extraocular muscles. METHODS: Fresh autopsy specimens were obtained from a newborn and a 26 year-old male. The length of the inferior oblique nerve was analyzed with high magnification photomicroscopy and electron microscopy and compared to the nerve capsules of the adult medial, lateral, inferior and superior rectus muscles. These were also compared to the intracranial portion of the third cranial nerve of the adult specimen. RESULTS: The collagen layer of the nerve to the inferior oblique was present throughout its course. It is well developed in the newborn and comparable to the adult specimen. The nerves to the medial, inferior, lateral and superior rectus muscles are also surrounded by a similar capsule containing collagen fibers that are aligned parallel to the axon of the nerve. The intracranial portion of the third cranial nerve only has a thin fibrous capsule. CONCLUSION: The nerve capsule of the inferior oblique comprises a surrounding collagen layer, presumably to protect the nerve from stretching. This layer is well developed along the entire course of the nerve and is present from birth. The nerves to the other extraocular muscles have a similar capsule that likely serves a similar function. These findings expand current understanding of the nerves to the extraocular muscles and may be useful for improving treatments.

The neurofibrovascular bundle of the inferior oblique muscle as the ancillary origin of that muscle.

PURPOSE: To establish that the neurovascular bundle (NVB) of the inferior oblique muscle has ligamentous qualities that enable it to function as an ancillary origin to the muscle, particularly after anterior transposition of its insertion. METHODS: Fresh cadaveric eyes and eyes of surgical patients were studied. Eighteen orbits were dissected to demonstrate the linear course of the NVB and its adjacent fibrous bands. Intact orbits were analyzed histologically, as were autopsy and surgical specimens, to evaluate the capsule of the NVB and the adjacent fibrous bands. The elastic modulus was measured in NVB specimens and in superior oblique tendons. Six eyes in which recurrent inferior oblique muscle overaction developed after an anterior transposition procedure were surgically explored to determine the structure that was serving as its ancillary origin. RESULTS: Gross anatomic and microscopic studies showed a linear orientation of the NVB,with adjacent fibrous bands anteriorly joining the inferior oblique and inferior rectus muscle capsules. The NVB showed about 50% fibrocollagenous capsule, with the collagen fibers aligned parallel to the NVB. The elastic modulus was highest (stiffest) in the NVB and lowest in the superior oblique tendon. In patients who had undergone anterior transposition operations, the NVB served as the ancillary origin of the inferior oblique muscle. CONCLUSION: The name of the NVB should be changed to neurofibrovascular bundle because it has a prominent fibrocollagenous capsule and is encased in fibrous tissue bands anteriorly. The neurofibrovascular bundle has a linear course and is relatively stiff. It binds the midposterior portion of the inferior oblique muscle posteriorly. Its ligamentous qualities enable it to function as an ancillary origin for the inferior oblique muscle.

The critical period for surgical treatment of dense congenital unilateral cataract.

PURPOSE: Early treatment of dense congenital unilateral cataract is associated with better acuity outcomes. It is unclear whether there is a gradual worsening of prognosis with delay of treatment from the time of birth (linear model) or whether there exists an early window of time during which treatment is maximally effective, followed by declining success (bilinear model). The aim of the current study was to determine which model better describes the response to treatment. METHODS: A maximum likelihood procedure that permits statistical comparison between linear and bilinear models was applied to acuity outcomes from a group of 45 children 5 to 8 years of age with a history of dense congenital unilateral cataract diagnosed at 1 to 10 days of age. Contrast sensitivity and vernier acuity data from a subset of these children were evaluated with nonparametric statistical methods. RESULTS: The bilinear model provided a significantly better fit to the acuity outcome data. The line fitted to the initial portion of the function had a shallow slope that was not significantly different from 0.0. The intersection of the two linear functions occurred at 5.6 weeks and was followed by a steep decline in visual acuity outcomes. Contrast sensitivity and vernier outcome measures over a range of spatiotemporal conditions showed better outcomes were obtained with early treatment. CONCLUSIONS: Intervention before 6 weeks of age may minimize the effects of congenital unilateral deprivation on the developing visual system and provide for optimal rehabilitation of visual acuity.

The neurofibrovascular bundle of the inferior oblique muscle as its ancillary origin.

PURPOSE: To establish that the neurofibrovascular bundle (NFVB) of the inferior oblique muscle (IO) has ligamentous qualities that enable it to function as an ancillary origin to the muscle. Also, to show that the NFVB does function as the ancillary origin for the IO muscle, particularly when recessing and anteriorly transposing its insertion. METHODS: Fresh (no formaldehyde preservative) cadaver and patient eyes were studied anatomically, histologically, and physiologically. Eighteen orbits were dissected to isolate the IO, the inferior rectus (IR), and the NFVB to demonstrate the linear course of the NFVB and its adjacent fibrous bands. The shape of the muscle was documented. Coronal sections of the two whole, intact orbits were analyzed histologically. Light and electron microscopic sections of an autopsy specimen and a surgical specimen were used to evaluate the capsule of the NFVB and the adjacent fibrous bands near the anterior portion of the NFVB and their attachment to the IR and IO muscle capsules. The elastic modulus was measured in six in situ and six in vitro cadaver NFVB specimens and in six in vivo surgical cases at the time of denervation of the NFVB. For additional comparison, four in vitro cadaver superior oblique tendons were similarly tested. Six eyes that developed recurrent IO overaction following an anterior transposition procedure were surgically explored to determine what structure was serving as its ancillary origin. RESULTS: Gross anatomic and microscopic studies showed a linear orientation of the NFVB with adjacent fibrous bands anteriorly joining the IO and IR muscle capsules. The surgical specimens of the anterior portion of the NFVB show about 50% nerve and 50% fibrocollagenous capsule with the collagen fibers aligned parallel to the NFVB. The elastic modulus was highest (stiffest) in surgical specimens of the NFVB and in situ cadaver NFVB, followed by in vitro cadaver NFVB and, finally, in vitro cadaver superior oblique tendon. In patients who have undergone anterior transposition surgery, the NFVB served as the ancillary origin of the IO. CONCLUSIONS: The name of the neurovascular bundle should be changed to the NFVB, since it has a prominent fibrocollagenous capsule and it is encased in fibrous tissue bands anteriorly. The NFVB has a linear course in the orbit from the apex to the IO muscle and is relatively stiff. The associated fibrous band extends posteriorly from the IO muscle capsule, encasing the nerve anteriorly and attaching 3 to 7 mm posteriorly into the capsule of the IR. The NFVB binds the mid posterior portion of the IO posteriorly. Its ligamentous qualities enable the NFVB to function as an ancillary origin for the IO.