Ultrasound biomicroscopy in the management of retinoblastoma.

PURPOSE: To determine the role of ultrasound biomicroscopy (UBM) in the management of children affected with retinoblastoma. METHODS: A review of clinical records of children with the diagnosis of retinoblastoma at the Hospital for Sick Children from January 1995 to December 2007, for whom UBM was used to determine the extent of intraocular tumor. Clinical characteristics were compared with UBM. Pathological correlation was performed for enucleated eyes. RESULTS: In total, 101 eyes of 75 patients were included in the final analysis. Only 11 eyes were diagnosed on UBM to have extension of the tumor anterior to the ora serrata, and were enucleated. Histopathological examination confirmed the anterior extension in all the 11 eyes. In total, 50 eyes were enucleated because of various reasons, such as poor visual prognosis (12 eyes), unilateral group D or E (23 eyes), recurrences (8 eyes), and treatment failure (7 eyes). None of those patients were found to have anterior extension of the disease on histopathological examination. UBM did not yield any false negative (0/50) or any false positives (0/11). CONCLUSIONS: The UBM provided a sensitive and reproducible visualization of the anterior retina, ciliary region, and anterior segment allowing a better staging of the advanced disease process. Primary assessment of the true extent of retinoblastoma is critical for the selection of an optimal management approach.

Occult wound leak diagnosed by ultrasound biomicroscopy in patients with postoperative hypotony.

PURPOSE: To describe the ability of high-frequency ultrasound biomicroscopy (UBM) to diagnose occult wound leaks as a cause for hypotony after cataract surgery. METHODS: Six patients with persistent hypotony after cataract surgery were sent for UBM examination. Slitlamp examination and gonioscopy of the 6 eyes had not revealed a cause for the hypotony. RESULTS: Ultrasound biomicroscopy showed subtle wound separation with shallow conjunctival elevation at the site of the cataract wound in the 6 patients. Two eyes had surgical repair of the subconjunctival wound leak, and the other 4 were treated medically. In the 2 eyes with surgically repaired wounds, the hypotony cleared after wound closure. Of the 4 medically treated eyes, hypotony resolved in 2 and 1 had a recurrence of hypotony. The other 2 eyes had fluctuating intraocular pressure for an extended period. CONCLUSIONS: Hypotony after cataract surgery occurred in 6 eyes due to subtle wound leaks difficult to detect by clinical observation. Ultrasound biomicroscopy can be a helpful aid to clinical examination in detecting these leaks.

Ultrasound detection of posterior scleral bowing in young patients with choroidal melanoma.

BACKGROUND: In evaluating young patients with choroidal melanomas, which are uncommon in people less than 30 years old, we noted that some had the ultrasound appearance of posterior scleral bowing. The purpose of this study was to determine the incidence of posterior scleral bowing in young patients with choroidal melanoma. METHODS: We reviewed the ultrasonograms of 24 patients less than 30 years of age (mean age 25 years [standard deviation (SD) 4.7 years]) who presented to an ocular oncology service in Toronto between May 1984 and May 1997. In all cases the diagnosis was choroidal melanoma. Histologic specimens were available in six cases. RESULTS: Scleral indentation posterior to the normal curvature of the globe was identified in 14 patients (58%). These patients had a mean tumour height of 4.4 mm (SD 2.0 mm) and mean tumour diameter of 9.5 mm (SD 2.9 mm). In the 10 patients with no scleral bowing the mean tumour height was 5.7 mm (SD 3.1 mm) and mean tumour diameter 11.5 mm (SD 3.8 mm). Pathological study (results available in nine cases in the scleral bowing group and four cases in the group without bowing) showed that all the tumours in the former group and three of those in the latter group were of the more indolent cell types, either mixed with predominantly spindle cells, or spindle cell. The six patients with histologic specimens were all in the scleral bowing group. The histologic features supported the ultrasound finding of posterior scleral bowing. No transscleral invasion occurred over the tumour region. INTERPRETATION: Posterior bowing of the sclera at the tumour site was observed in over half of young patients with choroidal melanoma. This phenomenon can be detected by ultrasonography and has a different appearance from that of choroidal excavation.

Subretinal abscess due to Nocardia farcinica infection.

PURPOSE: Nocardia infection of the eye is uncommon. A case of choroidal abscess due to Nocardia farcinica infection is presented, and the literature is reviewed. METHODS: A 41-year-old immunocompromised man with chronic myeloid leukemia developed a unilateral choroidal abscess. N. farcinica was isolated from a simultaneous subcutaneous abscess and both infections responded to systemic sulfonamide therapy. RESULTS: Three weeks after discontinuation of the sulfonamides, the choroidal abscess recurred with involvement of the vitreous. The infection was brought under control after reinstitution of the same drug. CONCLUSIONS: Nocardiosis is a multisystem disease that has high mortality and ocular morbidity rates. The eyes of immunocompromised patients should be examined frequently as early detection and administration of the proper antibiotics may reduce the risk of this life-threatening infection.

Advances in ultrasound biomicroscopy.

The visualisation of living tissues at microscopic resolution is attracting attention in several fields. In medicine, the goals are to image healthy and diseased tissue with the aim of providing information previously only available from biopsy samples. In basic biology, the goal may be to image biological models of human disease or to conduct longitudinal studies of small-animal development. High-frequency ultrasonic imaging (ultrasound biomicroscopy) offers unique advantages for these applications. In this paper, the development of ultrasound biomicroscopy is reviewed. Aspects of transducer development, systems design and tissue properties are presented to provide a foundation for medical and biological applications. The majority of applications appear to be developing in the 40-60-MHz frequency range, where resolution on the order of 50 microm can be achieved. Doppler processing in this frequency range is beginning to emerge and some examples of current achievements will be highlighted. The current state of the art is reviewed for medical applications in ophthalmology, intravascular ultrasound, dermatology, and cartilage imaging. Ultrasound biomicroscopic studies of mouse embryonic development and tumour biology are presented. Speculation on the continuing evolution of ultrasound biomicroscopy will be discussed.

A 100-200 MHz ultrasound biomicroscope.

The development of higher frequency ultrasound imaging systems affords a unique opportunity to visualize living tissue at the microscopic level. This work was undertaken to assess the potential of ultrasound imaging in vivo using the 100-200 MHz range. Spherically focused lithium niobate transducers were fabricated. The properties of a 200 MHz center frequency device are described in detail. This transducer showed good sensitivity with an insertion loss of 18 dB at 200 MHz. Resolution of 14 /spl mu/m in the lateral direction and 12 /spl mu/m in the axial direction was achieved with f/1.14 focusing. A linear mechanical scan system and a scan converter were used to generate B-scan images at a frame rate up to 12 frames per second. System performance in B-mode imaging is limited by frequency dependent attenuation in tissues. An alternative technique, zone-focus image collection, was investigated to extend depth of field. Images of coronary arteries, the eye, and skin are presented along with some preliminary correlations with histology. These results demonstrate the feasibility of ultrasound biomicroscopy In the 100-200 MHz range. Further development of ultrasound backscatter imaging at frequencies up to and above 200 MHz will contribute valuable information about tissue microstructure.

Primary cysts in the iridociliary sulcus: ultrasound biomicroscopic features of 210 cases.

BACKGROUND: Primary cysts occur spontaneously, whereas secondary cysts arise following surgical or nonsurgical injury and can lead to further complications. We performed a study to observe and characterize primary iridociliary cysts through the examination of ultrasound biomicroscopic (UBM) images from affected patients. METHODS: The UBM images from 210 patients were analysed and the characteristics of each cyst were observed and recorded. The patients had been examined and received the diagnosis of iridociliary cysts between 1990 and early 1998 at a major referral centre for the diagnosis and treatment of cancer in Toronto. RESULTS: Of the 210 cysts 169 (80%) occurred in isolation, and the remainder occurred in the presence of a tumour. The mean horizontal diameter of the isolated cysts was 1.72 mm, and the mean vertical diameter was 1.04 mm. Isolated cysts were solitary in 101 cases (60%) and showed multiple loculations in 68 (40%). Solitary cysts were slightly larger than those with multiple loculations. Isolated cysts were associated with markedly narrowed or closed angles locally in 110 cases (65%). INTERPRETATION: Primary iridociliary cysts are common and need to be differentiated from iris and ciliary body tumours. UBM is a definitive method of diagnosing these lesions. Cysts can cause localized angle closure but rarely cause clinical complications. Cysts associated with anterior segment tumours may give an erroneous impression as to tumour size.

Plateau iris syndrome: changes in angle opening associated with dark, light, and pilocarpine administration.

PURPOSE: To report changes in angle configuration associated with dark, light, and pilocarpine administration in plateau iris syndrome. METHOD: In 10 eyes of 10 patients with plateau iris syndrome and persistent narrow angles after patent peripheral Nd:YAG laser iridotomy, ultrasound biomicroscopy was used to image variations in angle opening, iris thickness, and trabecular-ciliary process distance. Measurements were taken in the dark, in full room light, and after administration of pilocarpine 2%. RESULTS: Average angle opening distance increased in the light compared with the dark (113+/-34 microm vs. 22+/-34 microm, P = .0001) and increased further after pilocarpine administration (171+/-52 microm vs. 113+/-34 microm, P = .0034). Average iris thickness decreased in the light compared with the dark (338+/-34 microm vs. 436+/-58 microm, P = .0009) and decreased further after pilocarpine administration (253+/-48 microm vs. 338+/-34 microm, P = .0002). Average trabecular meshwork-ciliary process distance measurements were smaller than normal and did not change significantly in the light compared with the dark (481+/-42 microm vs. 464+/-44 microm, P = .4001) or after pilocarpine administration compared with light (451+/-67 microm vs. 481+/-42 microm, P = .1304). CONCLUSIONS: In plateau iris syndrome, anteriorly located ciliary processes support the peripheral iris. Changes in angle opening in dark and light are solely related to changes in iris thickness. Pilocarpine produces iris thinning and is an effective method of opening the angle. Ultrasound biomicroscopy can be used to perform a darkroom provocative test, which provides information on whether the angle anatomically closes in the dark.

Follow-up of 3 patients with Ridley intraocular lens implantation.

Three patients in whom Ridley intraocular lenses (IOLs) were successfully implanted more than 42 years ago are presented. One case had traumatic cataract at age 13. The other 2 had surgery for unilateral cataract of unknown etiology at about age 40 and surgery on the second eye approximately 40 years later. A review of other reports of late-term results with this IOL is included.

Retinitis pigmentosa, nanophthalmos, and optic disc drusen: a case report.

OBJECTIVE: Although the associations of retinitis pigmentosa (RP) with nanophthalmos/microphthalmos and RP with optic disc drusen have previously been recognized, the concurrence of all three features, as far as the authors are aware, has not previously been reported. DESIGN: Case report. RESULTS: The authors report a sporadic case of nanophthalmos, RP, and optic nerve drusen with the additional complication of chronic angle closure glaucoma. CONCLUSIONS: Visual loss may be secondary to the complications of nanophthalmos, RP, or optic nerve drusen. Chronic angle closure may be caused by choroidal effusion with serous retinal detachment, which may, in turn, cause a pseudo-RP picture. It is therefore important to recognize the possible association of true RP with nanophthalmos as a cause for visual deterioration.

Ultrasound biomicroscopic quantitative analysis of light-dark changes associated with pupillary block.

PURPOSE: To quantitatively analyze the changes in anterior chamber angle and iris configuration induced by varying illumination in patients with narrow angles and pupillary block. METHODS: Twenty-four eyes of 24 patients with pupillary block (mean age, 52.5 years) had ultrasound biomicroscopic images of the angle and iris structures obtained superiorly, nasally, inferiorly, and temporally. Images were performed in the light and the dark. We measured the angle opening distance, iris thickness, iris chord length, iris-lens touch, and iris curvature. RESULTS: Changes in iris and angle configuration occurred within a few seconds of a change in lighting. The mean dark measurements were statistically significantly less than the mean light measurements for angle opening distance (96 +/- 18 vs 185 +/- 26 microm, P = .0001), iris chord length (2,505 +/- 61 vs 3,001 +/- 69 microm, P = .0001), and iris-lens touch (350 +/- 20 vs 693 +/- 35 microm, P = .0001). The mean dark measurements were statistically significantly greater than the mean light measurements for iris thickness at 500 microm from the scleral spur (367 +/- 10 vs 307 +/- 25 microm, P = .0001), and 1,500 microm from the scleral spur (404 +/- 14 vs 347 +/- 12 microm, P = .0001). Iris curvature in all four quadrants was statistically significantly greater in the dark than the light. CONCLUSIONS: This study quantitatively confirms that angle narrowing in the dark in eyes with pupillary block is associated with iris shortening, increased iris thickness, and increased iris convexity. Iris-lens touch is relatively small in pupillary block and decreases with dilation. Angle narrowing with dilation is not related to increased iris-lens touch and occurs promptly without requiring time for aqueous pressure buildup behind the iris.

Use of microbubble ultrasound contrast agent to demonstrate the iris valve effect in human eye bank eyes.

PURPOSE: To demonstrate that the interface between the normal iris and the lens surface functions as a flap valve. METHOD: Microbubble ultrasound contrast agent was injected into the anterior and posterior chambers of human eye bank eyes and the distribution of contrast imaged with high-frequency ultrasound. RESULTS: Contrast agent did not enter the posterior chamber when injected into the anterior chamber, but contrast agent injected into the posterior chamber easily flowed into the anterior chamber. CONCLUSIONS: The iris-lens interface normally functions as a flap valve, preventing retrograde flow from the anterior to the posterior chamber. A temporary increase in anterior chamber pressure thus results in iris concavity in pigmentary dispersion syndrome.

High-frequency Doppler ultrasound examination of blood flow in the anterior segment of the eye.

PURPOSE: To show that extending Doppler imaging into the high-frequency domain could allow detection and characterization of blood flow in small arterioles and capillaries. METHODS: A 40-MHz continuous wave Doppler system and a 60-MHz pulsed-wave Doppler system were constructed, tested, and used to examine the ciliary body region in two normal volunteers. RESULTS: Ciliary body circulation in the region of the great circle of the iris, which is undetectable by conventional 7.5-MHz duplex Doppler, was consistently and reproducibly detectable by high-frequency (40-MHz and 60-MHz) Doppler systems. CONCLUSION: High-frequency Doppler imaging may provide a unique new tool for the characterization and assessment of anterior segment ocular blood flow.

Imaging zonular abnormalities using ultrasound biomicroscopy.

OBJECTIVES: To evaluate the use of ultrasound biomicroscopy (UBM) in detecting ciliary zonular defects and to describe the UBM signs of such defects. METHODS: Eighteen eyes of 18 patients with clinically suspected zonular abnormalities were evaluated using UBM. Predisposing factors included pseudoexfoliation, congenital spherophakia, surgical procedure, trauma, and the Marfan syndrome. RESULTS: Of 18 eyes, 11 showed UBM evidence of missing zonules and 11 showed evidence of zonular stretch. Four of the 18 eyes had both missing and stretched zonular fibers. All of the eyes examined showed increased lenticular sphericity in the area of zonular disorder. Nine eyes showed ciliary body flattening. Pupillary block was seen in 5 patients, and angle crowding due to direct iridal rotation was noted in 3. CONCLUSIONS: Ultrasound biomicroscopy can detect zonular loss and stretching directly. Increased lenticular sphericity and ciliary body flattening are signs of zonular defects. Angle closure mechanisms include pupillary block and direct iridal rotation.

Ultrasound biomicroscopy in Sturge-Weber-associated glaucoma.

PURPOSE: To evaluate Sturge-Weber-associated glaucoma using ultrasound biomicroscopy. METHOD: Case report. Clinical examination combined with ultrasound biomicroscopy was performed in a patient with Sturge-Weber-associated glaucoma. RESULTS: In the patient's left eye, which had Sturge-Weber-associated glaucoma, a 360-degree supraciliary effusion, dilated superficial and intrascleral vessels, and an open angle were detected by ultrasound biomicroscopy. CONCLUSION: The presence of dilated intrascleral vessels and supraciliary fluid support the hypothesis of increased episcleral venous pressure as the cause of elevated intraocular pressure in this syndrome.

Ultrasound biomicroscopy. High-frequency ultrasound imaging of the eye at microscopic resolution.

UBM presents us with a new method of imaging the anterior segment of the eye at high resolution. Its strengths lie in its ability to produce cross-sections of the living eye at microscopic resolution without violating the integrity of the globe. UBM, although lacking the resolution of optical microscopy, gives us images in living eyes without affecting the internal relationships of the structures imaged. There are many other applications of this new imaging method. Examples of other uses include imaging adnexal pathology, assessing corneal changes with refractive surgery, the assessment of trauma, and determination of intraocular lens position.