Effect of acute intraocular pressure changes on short posterior ciliary artery haemodynamics.

BACKGROUND/AIMS: Vascular insufficiency due to abnormal autoregulation has been proposed as a major factor in the development of glaucoma. The anterior optic nerve is primarily perfused by the short posterior ciliary arteries. The autoregulatory capacity of these vessels in response to acutely elevated intraocular pressure (IOP) was examined in normal human subjects. METHODS: Colour Doppler imaging was performed on the short posterior ciliary arteries of 10 normal subjects at baseline and during four incremental IOP elevations. Using a scleral suction cup placed temporally, IOP was elevated to approximately 25, 30, 40, and 50 mm Hg. Additional measurements were performed immediately after pressure release. Systolic and diastolic flow velocities were measured and Pourcelot's resistivity index was calculated. RESULTS: Systolic and diastolic flow velocities decreased linearly with each incremental increase in IOP (p < 0.001). Pourcelot's resistivity index increased linearly with each incremental increase in IOP (p < 0.001). Changes in end diastolic velocity, peak systolic velocity, and Pourcelot's resistivity index were linearly related to changes in IOP. CONCLUSION: The normal healthy eye is not able to autoregulate to maintain PCA blood flow velocities in response to acute large elevations in IOP.

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.

Intraoperative echographic localization of iodine 125 episcleral radioactive plaques for posterior uveal melanoma.

PURPOSE: Plaque radiotherapy has been reported to have a higher relapse rate than charged-particle radiotherapy for posteriorly located uveal melanomas, which also are more technically difficult to localize accurately. The authors used intraoperative echography in patients with posterior uveal melanoma to determine the rate of inaccurate localization of iodine 125(125I) episcleral plaques using standard localization techniques. METHODS: The authors reviewed the records of 29 consecutive patients with medium-sized posterior uveal melanomas who underwent 125I episcleral plaque radiotherapy with intraoperative echographic verification of plaque placement. RESULTS: After careful plaque placement using standard localization techniques, 4 of 29 plaques (14%) did not cover at least one tumor margin. All four of these plaques were associated with posterior tumors with at least one margin posterior to the temporal arcades. Two (7%) additional juxtapapillary plaques were displaced away from the sclera by the optic nerve. In all six cases, it was possible to immediately reposition the plaque to achieve coverage of all tumor margins. CONCLUSIONS: Placement of 125I episcleral radioactive plaques for posteriorly located uveal melanomas using standard localization techniques occasionally results in suboptimal plaque positioning. Intraoperative echography can identify plaques that are localized poorly and allows immediate adjustment to achieve optimal plaque positioning.

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.

Diameter of normal extraocular recti muscles with echography.

To establish the range of diameters of normal extraocular muscles, we used standardized A-scan echography to measure the superior recti/levator complex, medial, lateral, and inferior recti muscles in 38 subjects with healthy orbital tissues. The relationships of age, gender, height, and weight to axial length of the globe were considered. These factors and extraocular muscle diameters were not consistently associated. Our normative data were compared with previously reported studies of extraocular muscle diameter performed with standardized A-scan and contact B-scan echography and computed tomographic scanning.