Diameter of normal extraocular recti muscles with echography

Echographic characterization of extraocular muscles in pediatric patients with thyroid dysfunction

PURPOSE

To characterize the size of extraocular muscles (EOMs) in a pediatric population with thyroid dysfunction using orbital echography.

METHODS

Patients under age 18 with thyroid dysfunction who presented to an academic ophthalmology department from 2009 to 2020 and received orbital echography were included in this IRB-approved retrospective study. Data collected included age, clinical activity score (CAS), thyroid stimulating immunoglobulin (TSI), and extraocular recti muscle thickness on echography. Patients were organized into three age cohorts, after which statistical analysis compared recti measurements to previously reported normal ranges.

RESULTS

Twenty patients with thyroid dysfunction were included. When comparing average recti muscle thicknesses of study patients to those of previously published normal children in similar age ranges, the levator-superior rectus complex was significantly increased in all age groups of children with thyroid dysfunction (p-values = <.004), and the levator-superior rectus complex was most frequently enlarged compared to published normal values (78% of eyes). CAS was not correlated with EOM size in the youngest group (5-10 years old, p-values >.315) but was significantly correlated in older groups (11-17 years old, p-values <.027). TSI was not correlated with EOM size in any group (p-values >.206).

CONCLUSIONS

Echographic reference ranges for EOMs in children with thyroid dysfunction were established. There are increased rates of levator-superior rectus complex enlargement in children with TED compared to adults with TED, and EOM size is correlated with CAS in children older than 10 years. Though limited, these findings may serve as an additional tool for ophthalmologists to ascertain disease activity in pediatric patients with thyroid dysfunction.

Do rectus muscle parameters vary between emmetropes and myopes?

PURPOSE

This study investigated the thickness, area, and insertion site of the medial (MR) and lateral (LR) rectus muscles in individuals with emmetropia and different degrees of myopia.

METHODS

Swept-source optical coherence tomography images of the MR and LR muscles in 80 participants including emmetropes (spherical equivalent refractive error [SER] ±0.50 D, N = 14) and myopes (≤ -0.75 D, N = 66), were analysed. Custom-designed, semi-automated software was used to measure parameters such as insertion distance from limbus, muscle thickness at every 1 mm interval to 3 mm periphery and muscle area from insertion site to 3 mm.

RESULTS

The median (Q1, Q3) SER error and axial length were -6.00 D (-13.25, -2.12) and 25.78 mm (23.78, 28.61), respectively. The MR was significantly thinner (mean ± SE: 137.7 ± 8.9 vs. 159.7 ± 8.9 µm, p < 0.01) and occupied less area than the LR (0.35 ± 0.01 vs. 0.42 ± 0.01 mm² , respectively, p < 0.01). The thickness of the MR gradually increased from the insertion site to a 3 mm peripheral eccentric location (106.5 3.8 µm at 1 mm, 135.5 ± 4.5 µm at 2 mm and 156.1 ± 5.9 µm at 3 mm, p < 0.01). The overall median thickness of the MR was significantly less in myopes (129 µm [111.5, 152.2]) than emmetropes (158.1 [134.3, 167.7] µm, p = 0.03). However, no such trend was seen in the LR muscle. Muscle area and insertion distance were not different between emmetropes and myopes in both horizontal rectus muscles.

CONCLUSION

Unlike the LR, the parameters of the MR (thin and occupying less area) show significant association with myopia. While the key finding of this study indicates the possible association of MR parameters with myopia, the clinical relevance of this finding and its role in myopiogenesis/progression needs to be investigated further.

Assessment of extraocular muscle thickness and correlation study using optical coherence tomography

OBJECTIVE

To report reference values for the horizontal rectus muscles thickness using Spectral Domain optical coherence tomography (SD-OCT), and to evaluate whether there are any correlations between the muscle thickness and gender, age, or axial length (AL).

MATERIAL AND METHODS

A cross-sectional study was conducted on 131 right eyes of healthy subjects. The gender and age were recorded, and axial length was measured using an optical biometer. The medial rectus (MR) muscle thickness was measured at 7.2 and 9.2mm from the limbus, and the lateral rectus (LR) at 8.5 and 10.5mm from the limbus using OCT. A multivariate model was adjusted to determine whether gender, age, and axial length could have an impact on the muscle thickness.

RESULTS

Mean age was 43.3±20.9 years (range 6-86), and 59% were women. Mean AL was 24.9±2.7mm (range: 20.4-33.8). Mean thickness was 188.5±51.2μm (range 69-342) for the LR at 8.5 and 186.5±45.9μm (range 75-269) at 10.5mm, and for the MR, 158.1±39.1μm (range 69-273) at 7.2mm and 193.7±55.9μm (range 105-386) at 9.2mm. A correlation was observed between the AL and MR thickness (R=-.255; P=.023) while no correlation was observed for the LR (P≥0.203). No correlations were found between thickness and gender or thickness and age (P≥0.125).

CONCLUSIONS

The reference ranges of the horizontal rectus muscles thickness was described using SD-OCT, observing an association between the AL and the MR thickness.

Diagnostic Ophthalmic Ultrasound for Radiologists

Ophthalmic ultrasound is an invaluable tool that provides quick and noninvasive evaluation of the eye and the orbit. It not only allows the clinicians to view structures that may not be visible with routine ophthalmic equipment or neuroimaging techniques but also provides unique diagnostic information in various ophthalmic conditions. In this article, the basic principles of ophthalmic ultrasound and examination techniques are discussed. Its clinical application is illustrated through a variety of ocular pathologic abnormalities (eg, narrow angles, ciliary body tumor, detached retina, choroidal melanoma, and papilledema).

Association of dry eye and inflammatory systemic diseases in a tertiary care-based sample

PURPOSE

The aim of this study was to review the frequency and types of inflammatory systemic diseases in a cohort of patients with dry eye, and identify clinical features suggesting the presence of these.

METHODS

Consecutive new patients with a primary diagnosis of dry eye evaluated at a tertiary dry eye center between January 2010 and December 2011 were reviewed retrospectively. Standardized questionnaires were used to obtain data regarding systemic symptoms, previous medical diagnoses, and family history. Dry eye evaluations included Schirmer testing, tear film break-up time, corneal fluorescein staining, and bulbar conjunctival lissamine green staining. Clinically significant dry eye was defined as having a Schirmer test score without anesthesia of ≤10 mm or conjunctival lissamine green staining of ≥1 using the Oxford scale.

RESULTS

A total of 228 new patients were analyzed. Of these, 47.4% (108/228) presented with a known diagnosis of inflammatory disease. Based on a review of systems and ocular examination, 81 patients (81/228) underwent a further work-up that revealed 25 additional diagnoses that were not known on presentation. The most common newly identified conditions included occult thyroid eye disease (n = 20), primary Sjögren Syndrome (4), and Sjögren Syndrome suspect (1). Female gender, family history of autoimmune disease, self-reported joint pain or dry mouth, external signs of orbital inflammation, and conjunctival chemosis were more common in patients with inflammatory systemic disease as compared with that in patients with no identifiable condition (P < 0.05 for all).

CONCLUSIONS

Systemic inflammatory diseases are frequently associated with dry eye in patients evaluated at a tertiary academic center. Diagnostic evaluations may help uncover previously undiagnosed significant conditions in about one-third of tested patients.

Echographic study of extraocular muscle thickness in normal Indian population

PURPOSE

To establish normative data of extraocular muscle (EOM) dimensions, both vertically and horizontally, using a reproducible echographic method in various age groups.

METHODS

Two hundred eyes of 100 healthy subjects (50 males and rest females) were included in this prospective observational study. All subjects were divided into 5 groups with an interval of 10 years from 10 to 60 years. Each group contained 10 male and 10 female healthy subjects. A single operator took measurements at 4 mm distance from the globe plane after drawing a perpendicular line on the globe to the muscle belly.

RESULTS

The average age of subjects was 37.28 ± 17.14 years. Intraobserver reproducibility was very high (intersession concordance correlation co-efficient = 0.995). Mean horizontal and vertical diameters of recti were 3.0775 and 8.26 mm, respectively. Mean muscle thickness of superior rectus/levator palpebral superioris (LPS) muscle complex and LPS was 4.56 and 1.45 mm, respectively. Extraocular muscle diameter increases up to the middle age, then it starts decreasing. There was no statistically significant correlation between diameter of each EOM, both eye and gender (p ⩾ 0.05). There was a non-significant change in extraocular muscle thickness with age.

CONCLUSION

The study provides normative data for extraocular muscle thickness in both genders of various age groups in Indian population. Muscle dimensions do not change significantly with age, between the eyes and gender.

Correlation between magnetic resonance imaging and ultrasound measurements of eye muscle thickness in thyroid-associated orbitopathy

AIMS

To compare ultrasound (US) and magnetic resonance imaging (MRI) measurements of horizontal eye muscle thickness in patients with thyroid-associated orbitopathy (TAO) and to compare these measurements according to the phase of the disease, the severity of exophthalmos, and the experience of the investigator.

METHODS

A total of 180 orbits of adult patients with TAO were investigated from May 2007 to December 2012. In addition to their general ophthalmic examination, all patients underwent ultrasonographic measurement of horizontal eye muscle thickness with the B-scan technique and MRI examination of the orbit. Correlations between values obtained by US and MRI were determined for different subgroups according to disease activity (active, inactive), exophthalmos values (Hertel < 18 mm; Hertel 18-22 mm; Hertel > 22 mm), and the time period of examination (2007-2009; 2010-2012).

RESULTS

Positive moderate correlation between US and MRI values for the medial rectus muscle (MRM; r = 0.690) and for the lateral rectus muscle (LRM; r = 0.572) was found. Significantly higher correlation was found for the MRM (P < 0.0001) and the LRM (P = 0.0008) in the time period 2010-2012 than in that of 2007-2009. Increasing correlation was found for MRM with increasing values of exophthalmos but this increase was not statistically significant. In the active phase of the disease compared to the inactive phase, statistically significant increased correlation (P = 0.019) was found for the LRM.

CONCLUSIONS

Ultrasonographic measurement of horizontal eye muscles thickness in TAO moderately correlates with values obtained using MRI. The accuracy of ultrasonographic measurements in particular increases with the experience of the investigator.

Repeated triamcinolone acetonide injection in the treatment of upper-lid retraction in patients with thyroid-associated ophthalmopathy

OBJECTIVE

To evaluate the efficacy and safety of repeated subconjunctival injections of triamcinolone in the treatment of upper-lid retraction with thyroid-associated ophthalmopathy.

DESIGN

Interventional controlled retrospective clinical study.

PARTICIPANTS

We studied 23 eyes in 15 patients as the nontreatment control group and 35 eyes in 21 patients as the treatment group.

METHODS

In the treatment group, triamcinolone acetonide was subconjunctivally injected into each lid as 4 doses of 20 mg at 1-month intervals. After the treatment, the eyes were divided into 2 groups, response and nonresponse, based on the improvement in margin reflex distance. The eyes of the nontreatment group received no medicine. The eyes were examined regularly.

RESULTS

The rate of spontaneous improvement in the nontreatment group was 17.4%. The mean rate of effectiveness was 68.6%. The improvement of upper-lid retraction was 2.31 mm (0 to 7 mm). The margin reflex distance was significantly smaller at 1 month after the initiation of treatment. Mean lid retraction time before treatment was 4.58 months in the response group versus 9.91 months in the nonresponse group. In the eyes presenting upper-lid retraction up to 6 months before treatment was initiated, the response rate was 83.3%. The response rate was only 36.4% when lid retraction developed more than 6 months before the procedure. The muscle thickness of the levator/superior rectus complex was significantly reduced after treatment in the response group (5.13 ± 0.85 mm at last follow-up vs. 5.69 ± 0.93 mm at baseline).

CONCLUSIONS

Repeated subconjunctival injection of triamcinolone is an effective and safe treatment for upper-lid retraction due to thyroid-associated ophthalmopathy.

Ultrasonography compared to magnetic resonance imaging in thyroid-associated Graves' ophthalmopathy

OBJECTIVE

To compare ultrasonography (US) to magnetic resonance imaging (MRI) and the clinical activity score (CAS) in Graves' ophthalmopathy.

SUBJECTS AND METHODS

Nineteen patients underwent extraocular muscle thickness measurements by US and MRI, reflectivity by US and signal-intensity ratio by MRI. There were also twelve US control subjects.

RESULTS

US median thicknesses were greater than in controls. Correlation was found between US and MRI in the median thickness of the left eye rectus medial muscle as well as between signal-intensity ratio (SIR) and thickness by US. An inverse correlation was found between reflectivity and SIR in the inferior and lateral rectus. On associating the tests for detecting activity the best results were obtained with CAS plus MRI (sensitivity 75%), and US and MRI (positive predictive value 77% and specificity 80%).

CONCLUSION

CAS and US results showed poor correlation with MRI results suggesting that they cannot replace each other but when combined these methods can improve the evaluation of thyroid-associated ophthalmopathy.

Occult thyroid eye disease in patients presenting with dry eye symptoms

PURPOSE

To describe the clinical presentation, laboratory features, and treatment outcomes in a series of patients with occult thyroid eye disease (TED).

DESIGN

Retrospective observational case series.

METHODS

Among 539 patients who were referred for dry eye evaluation over 2 years, 21 were diagnosed with occult TED, based on typical findings in orbital echography. Medical records of these patients were reviewed to collect information on demographics, clinical findings, laboratory studies, and treatment response.

RESULTS

All patients presented with symptoms of dry eye. Median age of patients was 57 years (range, 24 to 78 years), with the majority female (86%). No patients carried prior diagnosis of TED or had typical findings of TED such as proptosis, dysmotility, or diplopia. Suspicion of TED was based on conjunctival hyperemia with or without chemosis localized to extraocular muscles (100%), and subtle widening of interpalpebral fissure (48%). Clinical findings included corneal fluorescein staining (57%), rapid tear break-up time (31%), and abnormal Schirmer test (19%). Nineteen percent of patients had other rheumatologic disorders commonly associated with dry eye: Sjögren syndrome (n = 3), and rheumatoid arthritis (n = 1). Patients were treated topically using cyclosporine 0.05% 2 to 4 times a day, with or without steroid. Other treatments were also employed as necessary including warm compresses, artificial tears, and puntal plugs. Majority of patients (76%) had improvement of their symptoms.

CONCLUSION

Occult TED is a potential cause of inflammatory ocular surface disease with dry eye symptomatology and should be considered in the differential diagnosis when evaluating dry eye patients.

Magnetic resonance imaging and ultrasound measurements of extraocular muscles in thyroid-associated ophthalmopathy at different stages of the disease

PURPOSE

To assess extraocular muscle (EOM) involvement in thyroid-associated orbitopathy (TAO) of different stages with magnetic resonance imaging (MRI) and ultrasound techniques.

METHODS

A total of 32 patients with TAO were divided into three groups according to whether they had mild active, pronounced active or longstanding inactive disease. Six patients with Graves' disease but no clinical signs of TAO and 10 healthy control subjects were also studied. Muscle volume and cross-sectional area were measured with MRI. A-scan ultrasound was used to measure muscle thickness.

RESULTS

The average MRI volume and maximal cross-sectional area of the EOM were significantly larger in patients with pronounced active and longstanding inactive TAO than in control subjects. Increased average muscle thickness measured by ultrasound was found mainly in patients with longstanding disease. Muscle enlargement was seen with MRI and ultrasound in individual patients in all patient groups, including those with Graves' disease but no TAO. Bilateral muscle enlargement was revealed by MRI in about two-thirds of patients with mild active TAO and in all patients with pronounced active and longstanding inactive TAO. Bilateral involvement estimated with ultrasound was less common in all patient groups. The MRI and ultrasound findings were not well correlated in any patient group.

CONCLUSIONS

Extraocular muscle enlargement was seen in all patient groups with TAO of differing levels of severity. Measurements with MRI of muscle volume or maximal cross-sectional area are considered good indicators of muscle enlargement in TAO.

Occult thyroid eye disease in patients with unexplained ocular misalignment identified by standardized orbital echography

PURPOSE

To describe the clinical presentation, orbital echography (OE) findings, and neuroimaging results of patients with chronic unexplained ocular misalignment, which includes patients with clinically occult thyroid eye disease (TED) that is identifiable through a characteristic OE appearance.

DESIGN

Retrospective observational case series.

METHODS

Seventy-eight patients with chronic ocular misalignment suspected of TED because of a history of systemic thyroid disease, proptosis, dysmotility, positive forced ductions, or eyelid retraction or lag were categorized as TED positive, negative, and indeterminate with the use of standardized OE. Demographic, clinical, OE, computed tomography, and magnetic resonance imaging information was collected. Analyses determined the prevalence of TED and differences between TED positive, negative, and indeterminate groups.

RESULTS

Fifty-five percent of the findings were suspicious for and most consistent with TED (TED positive); 26% of the findings were TED negative, and 19% of the findings were TED indeterminate. Of 30 patients with newly diagnosed TED by OE, 70% had no lid retraction, and 20% had no other findings of TED. The inferior rectus followed by the superior rectus/levator complex, medial rectus, and lateral rectus muscles were the most frequently involved muscles. Neuroimaging that was performed in only 26 of 78 patients (33%) did not appear to yield additional diagnostic information.

CONCLUSION

TED is a potential cause of chronic unexplained ocular misalignment in a substantial proportion of patients. These patients frequently present in an occult fashion without other clinical findings that are typical of TED. In these patients, a diagnosis of TED by OE can reduce further costly evaluation. OE appears to have significant clinical usefulness in the diagnosis of TED in patients with unexplained ocular misalignment.

Recent developments in Graves' ophthalmopathy imaging

Orbital ultrasound, computed tomography, and magnetic resonance are commonly used as imaging techniques to demonstrate pathological changes in ocular adnexa of patients with Graves' ophthalmopathy. Low cost, short time of investigation, and lack of radiation characterize ultrasound. Nevertheless, a clear differentiation regarding disease activity is not possible, nor is the evaluation of orbital tissue precise enough. Short investigation time, precise imaging of the orbital apex and moderate costs are advantages of tomography. This method delivers a significant radiation dose to the lens, which if repeated constitutes a risk for cataract development. For this reason, magnetic resonance imaging is preferable, particularly if repeated scans are required to assess response to treatment. Precise tissue differentiation and lack of ionizing radiation uniquely suit magnetic resonance for eye studies. Although sensitive in demonstrating interstitial edema within the rectos muscles in active disease, as well as providing a good predictive value with respect to immunosuppressive therapy, quantitative magnetic resonance imaging is an expensive method and is non-specific for the orbital changes in ophthalmopathy. Because of a favorable target to background ratio, octreoscan carries a high sensitivity and may be regarded as a semi-objective tool in the evaluation of patients with Graves' ophthalmopathy, both at initial stages as well as during treatment. A positive orbital octreoscan indicates a clinically active disease in which immunosuppressive treatment might be of therapeutic benefit. However, it is an expensive method with a non-negligible radiation burden. Also, it is neither specific nor does it offer detailed orbital imaging. In summary, in unclear cases of proptosis or recently developed diplopia, prior to orbital decompression surgery, or if imaging is needed in subjects with ophthalmopathy, magnetic resonance actually is the imaging method of choice.

Ultrasonically measured horizontal eye muscle thickness in thyroid associated orbitopathy: cross-sectional and longitudinal aspects in a Danish series

PURPOSE

To analyse horizontal extraocular muscle findings by ultrasound and exophthalmometry in a tertiary endocrinology centre series of patients with thyroid associated orbitopathy (TAO).

METHODS

The 90 thyroid patients included underwent ultrasonic measurement of horizontal eye muscle thickness by a B-scan based technique carried out in addition to their general ophthalmic evaluation. As an indicator of mainly advanced TAO, longterm prednisone or cyclosporine A was given to many of the patients, and drug-resistant visual loss indicated decompression surgery in four of the 90 patients. Thirty-four patients underwent repeated muscle recordings over 15-49 months; this allowed for cross-sectional analysis and the outlining of longitudinal trends.

RESULTS AND CONCLUSIONS

(A) Although marginally overlapping, all four muscle groups were significantly thicker in the study group than in normal control subjects. The mean of the sum of all four muscles was 16.8 mm (range 13.6-21.7 mm) in the control group versus 22.6 mm (range 15.5-36.4 mm) in the thyroid group. (B) Using the clinical NOSPECS grading, more advanced eye involvement was found to generally result in a higher exophthalmometric measurement of protrusion and eye muscle thickness. However, slender rectus muscles and/or normal exophthalmometric values might occur even in advanced orbitopathy. (C) Over a period of 2-4 years, only a few of 34 patients with satisfactory serial ultrasonic measurements returned to their premorbid ophthalmic status. Typically, the extraocular muscles kept their abnormal size after having become clinically quiescent (fibrotic). (D) We found no safe indication regarding disease stage, active or late, from the ultrasonic appearance of the muscle tissue. (E) Discrepancies between various normative eye muscle studies are discussed with regard to computer tomography and magnetic resonance imaging.

Echographic study of extraocular muscle thickness in children and adults

BACKGROUND

Echobiometric evaluation of extraocular muscles in normal subjects has been performed previously, but only in adults. We determined extraocular muscle thickness in normal subjects in three age groups.

METHODS

Extraocular muscle thickness was studied in 75 normal subjects divided into three age groups (5-10, 11-15 and 28-37 years) using a Biovision B-scan-S instrument in standardized A-mode (frequency, 10 MHz; biometry resolution, 0.15 mm; depth, 40-60 mm; points on X axis, 512; levels on Y axis, 256). All measurements were performed by the same operator and repeated five times. The reproducibility of the technique was determined using the coefficient of variation. The one-way ANOVA test was used to compare the three groups, and the two-tailed unpaired t-test was used to compare subjects aged 5-10 years and those aged 11-15 years, and subjects aged 11-15 years with those aged 28-37 years.

RESULTS

The technique showed good reproducibility. In subjects 5-10 years old, the coefficient of variation was 8%; in subjects 11-15 years and 28-37 years old, it was 5%. Increased muscle thickness was observed with age (p < 0.001). A statistically significant difference between the medial and inferior recti muscles in subjects 11-15 years and 28-37 years old was found (p < 0.001).

CONCLUSIONS

The increased thickness of all recti muscles may be influenced by growth (primarily during puberty), and the variations in thickness of the extraocular muscles may be attributable to near-vision stimulus of the inferior and medial recti muscles.

Normative measurements of orbital structures using MRI

PURPOSE

The purpose of this work was to establish criteria for the diameters of normal extraocular muscles and superior ophthalmic vein and width of the optic nerve-sheath complex, to determine normal globe position as seen on MRI, and to investigate the effects of age and sex on these structures.

METHOD

Diameters of the extraocular muscles and superior ophthalmic vein, width of the optic nerve-sheath complex, and distance from the interzygomatic line to the posterior margin of the globe were calculated for 200 normal orbits of 100 patients on T1-weighted MR scans.

RESULTS

Normal ranges for diameters of the extraocular muscles were as follows (mean +/- 2 SD): medial rectus, 3.2-4.9 mm; lateral rectus, 2.6-4.8 mm; inferior rectus, 3.7-6.0 mm; superior group, 3.1-5.6 mm; superior oblique, 2.4-4.1 mm. The normal position of the posterior pole of the globe was 8.9 mm behind the interzygomatic line (range 5.0-12.7 mm). The mean diameters of the extraocular muscles in male patients were significantly larger than those in female patients (p < 0.001).

CONCLUSION

These data may be of value in quantitatively evaluating MRI of the orbit.

Correlation Between Clinical and Histological Analyses in Retroocular Connective Tissues and Extraocular Muscles from Patients with Graves' Ophthalmopathy

Twenty-two patients with Graves' ophthalmopathy underwent biopsy, and two patients had both eyes biopsied. The samples for the control group (n = 4) were obtained during routine non-thyroid-related corrective strabismus surgery. Ophthalmological evaluation with clinical activity score (CAS), endocrinological evaluation, and ultrasound were used in our study. Correlation between clinical and histological analyses in connective tissues and extraocular muscles from patients with Graves' ophthalmopathy was done. The echography results disclosed an enlargement in all extraocular recti muscles with the exception of one patient. Periodic acid-Schiff and Giemsa stains revealed a moderate number of mast cells in the endomysial connective tissue, none of which displayed significant degranulation. There were no signs of muscle cell damage. Fifteen of the biopsies showed weak cellular reactions with only scattered inflammatory cells. Furthermore, the inflammatory process may be localized and not equally distributed throughout the muscle. Thus, the biopsies might not be representative for the whole muscle. Statistical significance analysis was found when sex and CAS were compared (p = 0.001683) using the Fisher Test. In conclusion, our investigation indicates a pleomorphic pattern of histologic findings in connective tissue and extraocular muscles in Graves' ophthalmopathy.

The measurement of change in Graves' ophthalmopathy

Precise measurements of treatment response are a prerequisite for correct interpretation of therapeutic benefit. In the field of Graves' ophthalmopathy we have relied for too long on methods of measurement that are poorly reproducible, subjective, and that often rely on indices derived from aggregated measurements and subjective impressions. In consequence, our conclusions about the benefits of particular therapies are frequently controversial. Until the pathogenic agent of Graves' ophthalmopathy has been identified and is measurable, we are forced to limit our observations to the consequences of the action of that agent. Two critically important consequences are swelling of the retrobulbar muscles and connective tissue and shortening of the extraocular muscle range of contraction. From these primary events all the clinical features of Graves' ophthalmopathy are derived. Effective treatment of Graves' eye disease will affect at least one of five relevant measurements. These are: lid fissure width, range of extraocular motion, diplopia fields, and volume of retrobulbar muscle and connective tissue. These measurements, selected to correspond to the claims of the particular therapy under study, are recommended as the indicators of choice in clinical trials.

Echographic evaluation and findings in metastatic melanoma to extraocular muscles

PURPOSE

Metastatic melanoma to the extraocular muscles is an extremely rare condition characterized by marked enlargement of the involved muscles. The authors describe the echographic characteristics of metastatic melanoma to extraocular muscles.

METHODS

The authors used standardized echography (standardized A-scan and contact B-scan) to examine two patients known to have malignant melanoma elsewhere with metastatic melanoma to the extraocular muscles. Both patients had orbital lesions with similar echographic characteristics.

RESULTS

Echographically, metastatic melanoma to an extraocular muscle spares the tendon and produces marked thickening of the muscle belly fibers. Other echographic findings include low internal reflectivity, regular internal structure, and vascularity (similar to uveal melanoma). These previously unreported echographic features may be unique to metastatic melanoma to an extraocular muscle.

CONCLUSION

Echography can be a useful adjunct in detecting and diagnosing suspected metastatic melanoma to the extraocular muscles in patients with clinical signs of an orbital mass and known melanoma elsewhere or in the absence of a known primary lesion.

Venous stasis orbitopathy: a clinical and echographic study

AIMS

A variety of acute and chronic orbitopathies may be distinguished by standardised echography. Venous stasis orbitopathy (VSO) often presents with orbital signs when secondary to cavernous sinus and middle cranial fossa disorders. In this study, the aim was to assess whether differentiation between vascular and nonvascular causes of VSO could be made on the basis of clinical and echographic features at the time of presentation.

METHODS

This study comprised 37 patients with echographic features of VSO (17 patients with arteriovenous fistulae, confirmed by computed tomography imaging or angiography, and 20 patients with non-vascular diseases). Excluded were patients with orbital mass lesions detected by echography and muscle enlargement due to other causes (for example, orbital myositis). Patients with a suspected mass involving the orbital apex and echographic features of VSO were included. After full neuro-ophthalmic and ocular examination, both orbits were examined to document maximal thickness and reflectivity of four recti muscles and compared with the normal contralateral orbit with standardised A-scan (Kretz-technik 7200MA or Ophthascan) and contact B-scan (Ultrascan or Ophthascan S).

RESULTS

Cumulative ocular recti muscle thickness was significantly greater in patients with arteriovenous fistulae compared with the non-fistula group (23.3 (SD 3.7) and 17.8 (2) mm, p = 0.001). Clinically, the presence of a bruit and a uniocular rise in intraocular pressure were significantly greater in the fistula group of patients.

CONCLUSIONS

Standardised echography is a safe and non-invasive method of diagnosing VSO in patients presenting with signs of proptosis, ophthalmoplegia, and inflammation of the conjunctiva. Furthermore, using these standard techniques the two major causes of VSO (arteriovenous fistulae and compressive mass lesions) could be differentiated.

Echographic monitoring of response of extraocular muscles to irradiation in Graves' ophthalmopathy

PURPOSE

Confirmation of the efficacy of orbital irradiation in Graves' ophthalmopathy is needed due to the unpredictable natural history of the disease, the variation in individual clinical presentations, the contribution of other simultaneous treatments, and the lack of controlled studies using objective criteria to classify and assess response over time. Orbital echography before and at select intervals following orbital irradiation is proposed as an objective parameter of tissue response to orbital irradiation over time.

METHODS AND MATERIALS

From January, 1983 to September, 1993, 55 patients with progressive Graves' ophthalmopathy underwent 20 Gy retrobulbar irradiation. On retrospective review, standardized orbital echography was performed randomly prior to irradiation in 37 of the 55 patients to assess the acoustic characteristics of the extraocular muscles and to quantitate their individual and summed diameters. Twenty-one patients had at least one follow-up echographic evaluation at random intervals of 0 to 27.5 months following completion of irradiation. Twelve patients received steroids before or during irradiation, which were tapered in proximity to completion of radiation. Follow-up ranged from 2 to 65 months with the majority followed at least 6 months (18 patients).

RESULTS

Of the 21 patients with serial studies, 18 showed an interval decrease in individual and summed muscle size over time and return of symmetry. Interval improvement was documented as early as the 1 month follow-up study, with continued improvement seen during the 3-9-month studies, with stability typically achieved within 12 months. One patient had further changes between the 21 and 27.5 month follow-up studies. Exacerbation of disease was, however, echographically demonstrated in three patients at 6.5, 8.5, and 13 months. Follow-up studies in two of these patients again revealed improvement, one following tapered steroids. The third patient required orbital decompression.

CONCLUSION

Objective parameters of response are needed to document both the immediate and long-term outcome of orbital irradiation on the course of Graves' ophthalmopathy and confirm its efficacy. Serial echography is proposed as a new technique for providing parameters to judge response.

Clinical and echographic findings in idiopathic orbital myositis

We performed a retrospective chart review of 100 patients with idiopathic orbital myositis, who were of ages 9 to 84 years. Data from 75 patients gave the following results. Females were affected more than twice as often as males. Fifty-one patients (68%) had single muscle involvement, with the lateral and medial recti affected most frequently (38 cases [33%] and 33 cases [29%] of muscles, respectively). In 34 patients (45%), affected muscles functioned normally; the remaining 55% (63 muscles) were fairly equally distributed between paretic (20%), restrictive (20%), or combined paretic and restrictive (15%) myopathies. Analysis of muscle function, echographic findings, and duration of symptoms indicates that within days of onset of symptoms, the affected muscle is initially enlarged but retains normal function. Within the first two weeks, continued enlargement results in muscle paresis. The muscle may then enter a partially or completely restrictive phase, which may become permanent. Fifty-one patients (68%) responded well to systemic corticosteroids, although 11 patients (15%) had further recurrences of the disease. Seven patients (9%) later developed thyroid eye disease after initially having unimuscular orbital myositis. We advocate early institution of corticosteroids in order to avoid permanent restrictive myopathies.

Comparison of standardized echography with magnetic resonance imaging to measure extraocular muscle size

Using both standardized echography and high-resolution, surface coil magnetic resonance imaging, we measured the transverse diameter of recti extraocular muscles to evaluate comparative accuracy. Maximum transverse diameter of each rectus muscle in primary gaze was measured in 39 orbits of 20 subjects by using standardized A-scan echography. In the same orbits, we obtained multiple coronal magnetic resonance imaging planes by using a surface coil to span the anteroposterior extent of each orbit. Digital image analysis with the National Institutes of Health Image program was used to measure transverse muscle diameter. Average size for each rectus muscle was similar for the echographic and magnetic resonance imaging techniques. However, linear regressions of individual ultrasound against magnetic resonance imaging measurements showed coefficients of determination (R2) moderate (0.29) for inferior recti muscles and low (< or = 0.11) for other recti muscles. For most recti muscles, significant variability in echographic estimates of muscle width results from factors other than true muscle size. Results indicate that ultrasound measurements of muscle size in individual patients should be interpreted cautiously.

Vertical diplopia

An accurate clinical evaluation of vertical diplopia is predicated upon meticulous history-taking, observations regarding the presence and pattern of an anomalous head position, and the analysis of several subjective and objective tests of extraocular muscle function. To reach a final diagnosis with minimum risk and expense to the patient the examiner must be familiar with the neuroanatomy of the supranuclear and infranuclear pathways which control the actions of the vertically-acting extraocular muscles, the clinical methods and pitfalls of a number of clinical techniques which are used to identify an underacting extraocular muscle, and the hallmark characteristics of a supranuclear, infranuclear and restrictive ophthalmopathy.

Standardised echography in the differential diagnosis of extraocular muscle enlargement

Standardised echography is well documented for its use in the evaluation of enlarged extraocular muscles in orbital disease, but is still a largely underdeveloped imaging method in Britain. This paper demonstrates the technique of muscle ultrasound scanning and the characteristic echographic findings in a variety of extraocular muscle diseases, as illustrated by five case reports. The role of echography in the management of such cases is discussed.