Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmic Echography_Harrie_2008

MT is a 70-year-old woman who complained of blurriness of her right eye. She said that sometimes lines appeared wavy. Examination found 2+ nuclear sclerosis bilaterally and mild retinal pigment epithelial changes in both maculae. A fluorescein angiogram was performed and showed a few focal retinal pigment epithelial (RPE) window defects bilaterally but no other abnormalities.

Echography was performed and B-scan demonstrated partial separation of the posterior hyaloid face at the macula (Fig. 200). An impending macular hole was diagnosed and she was carefully followed for further evolution of the process. When she returned in 3 months her symptoms had subsided and repeat echography revealed complete separation of the vitreous. She was reassured that the risk of a macular hole was minimal because of the release of tractional forces.

Several drugs, such as plasmin, are being studied that may induce a PVD. This is postulated to be advantageous in certain high-risk patients, such as those with vitreoretinal traction at the macula, diabetics with high-risk characteristics for proliferative retinopathy, and high myopes with peripheral lattice degeneration. Echography is the ancillary modality in documenting the anatomy of the vitreoretinal interface in one such study.

The choroid contains most of the blood supply to the outer retina. Various disease processes can affect this tissue with resultant decrease in vision. Echography is able to document thickening of the choroid whether due to the edema of an inflammatory process, such as Vogt-Koyangi-Harada syndrome, or the solid thickening of a malignant process, such as en plaque melanoma.

FIG. 200. B-scan of posterior vitreous detachment with macular traction (arrow)

RA is a 52-year-old man who presented with the complaint of a drop in vision in his left eye over several months. Examination found visual acuity in his right eye of 20/25 and his left eye of 20/80-2. Anterior segment examination was normal and the intraocular pressure measured 16 OD and 19 OS. Fundus examination of the left eye found a diffuse grayish thickening of the macula and temporal choroid.

Echography was performed and a medium reflective solid thickening of the choroid was

demonstrated with moderate spontaneous vascularity (Fig. 201). The differential diagnosis included lymphoma, metastatic tumor, and en plaque melanoma of the choroid. A needle biopsy later confirmed the diagnosis of melanoma and the eye was enucleated.

Inflammatory cells as part of several diseases can invade the choroid. The adjacent retina and sclera can also be involved.

KG is a 43-year-old Hispanic migrant worker who had been struck in the right eye by a piece of metal as he was hammering on a metal rod. He did not seek medical care for several days because of his nonresident status, but finally the pain became intense and he went to the local emergency room. The small hospital in the rural area where he worked did not have an ophthalmologist on staff. The emergency room doctor put the patient on both oral and topical antibiotics and advised the patient to seek out a specialist in a city about 50 miles away. He delayed this for several more days and was finally seen by an ophthalmologist more than a week after the initial injury.

He was found to have a corneal-scleral laceration with iris to the wound. He was taken to surgery, where the laceration was repaired and necrotic uveal tissue was excised. He was noted to have a dense cataract and moderate anterior chamber reaction. The intraocular pressure in that eye was 5 mm and 16 mm in the left eye.

The fundus was imaged with echography and he was found to have diffuse retinochoroidal edema (Fig. 202). It was suggestive of early phthisis bulbi and only palliative treatment with topical anti-inflammatory drugs and cycloplegics was prescribed.

He was lost to follow-up for several months, but then returned to the ophthalmologist with complaints of some aching in his opposite eye with blurry vision. Examination found a phthisical right eye with no light perception and 20/50 in the left eye. Slit-lamp examination of the left eye found a mild flare in the anterior chamber and a slightly hazy vitreous. The retinochoroid layer appeared

FIG. 202. B-scan of choroidal thickening in pre-phthisis (arrow)

edematous and two foci were noted of yellowish infiltrates.

Echography was performed and mild thickening of the choroid was revealed with medium-to-high internal reflectivity (Fig. 203). This differential diagnosis first included sympathetic ophthalmia. The patient was immediately started on high-dose topical and systemic steroids with resolution of the process over several weeks and decreased choroidal thickening.

The optic nerve is derived from the axons of the retinal ganglion cells and is subject to some of the same inflammatory and malignant processes near its exit though the sclera. Its retrobulbar portion can be involved by orbital disease entities that do not involve the intraocular tissues. A common feature

of optic nerve pathology is reduced vision and the visual deficit is usually a central scotoma. A helpful test of optic nerve disease is to shine a penlight first in the normal eye and then the abnormal one. The patient is asked to grade the light intensity in each eye on a scale of 1 to 10. Color vision is a very sensitive test in the early phases of optic nerve dysfunction so the same eye-to-eye comparison can be made with a red target such as a mydriatic bottle

cap. These findings in association with an afferent pupil defect are highly characteristic of optic nerve involvement by a disease process.

The major processes that can involve the optic nerve are vascular, inflammatory, and neoplastic. Echography is especially helpful with the latter two but specialized ultrasound techniques such as color Doppler are required to evaluate blood flow abnormalities.

TH is a 51-year-old man who presented to the emergency room with a history of a sudden loss of vision in his right eye 3 hours previously. He was found to have vision in that eye of light perception with 20/20 in his left eye. An ophthalmology consult was requested and documented a 3+ afferent defect on the right and a cherry red spot in the fovea consistent with marked retinal edema. No emboli were seen.

Orbital color Doppler was performed the next day and the B-scan revealed embolic material posterior to the lamina cribrosa lodged in the central retinal artery (Fig. 204). This observation prompted a workup for a source. Carotid duplex scanning showed only a focal atherosclerotic plaque that was considered nonsignificant. Transesophageal echocardiography was performed and a calcific plaque was noted on the aortic valve. He was scheduled for open heart surgery with valve replacement.

The most common solid tumors of the optic nerve include gliomas in children and meningiomas in adults.

FIG. 204. B-scan of embolic material in central retinal artery (arrow)

JB is a 37-year-old woman with complaints of gradually decreasing vision over the past 9 months in her right eye. It seemed to fluctuate and at first she ascribed the symptom to overuse of her eyes on the computer. However, it continued when the stress of work had decreased and she became concerned enough to seek attention.

Examination found vision in the right eye of 20/30-1 and the left eye of 20/20. Exophthalmometry measured 2 mm of proptosis of the right eye. Intraocular pressures and the anterior segment were normal in both eyes. A 1+ afferent pupil defect was noted in the right eye. Fundus examination revealed engorged vessels on the surface of the right optic disc. A visual field examination demonstrated a central scotoma on the right and a normal field on the left.

An A-scan revealed thickening of the right nerve that measured 9.4 mm compared to 3.8 mm on the left. The nerve sheaths were abnormally thickened relative to the optic nerve (Fig. 205). A 30° test was negative on the right, which suggested a solid thickening of the nerve and was evidence against excess optic nerve sheath fluid as the cause.

An MRI scan demonstrated thickening of the optic nerve sheath consistent with optic nerve sheath meningioma (Fig. 206). The echographic and MRI findings were felt to be diagnostic and obviated the need for a nerve sheath biopsy. She was observed and as the vision declined she was referred for radiation therapy.

The optic nerve is subject to mechanical compression by processes other than neoplasms. Orbital hemorrhage subsequent to trauma can compress the nerve and result in visual loss.

FIG. 205. A-scan of optic nerve sheath meningioma (vertical arrows contacting nerve sheath and small middle arrow touching nerve parenchyma)

FIG. 206. Magnetic resoance imaging of optic nerve sheath meningioma (arrow)

HA is a 25-year-old man who was struck by a car while riding his bike. He was thrown onto the pavement and suffered head injury with a concussion. He was evaluated in the emergency room with CT scanning and no skull fracture was noted. He was admitted for overnight observation in the hospital. The next morning he complained of hazy vision in his right eye. An ophthalmology consult was obtained and the examination found vision OD of 20/80 and OS of 20/20. A 2+ afferent pupil defect was noted in the right eye. Slit-lamp and fundus examination were unremarkable. The CT scan was reviewed and showed widening of the right optic nerve sheaths (Fig. 207).

FIG. 207. Computed tomography scan of widened optic nerve sheath (arrow)

FIG. 208. A-scan of optic nerve sheath hemorrhage (small vertical arrows point to optic sheath)

Echography showed thickening of the right nerve that was measured at 5.4 mm versus 3.2 mm on the left (Fig. 208). The nerve sheath appeared to be thickened. There was a mildly positive 30° test with reduction of the right nerve sheath-to- sheath diameter to 4.1 as he looked to the right. In the clinical setting of trauma, these findings were felt to be most consistent with optic nerve sheath hemorrhage. The patient was carefully observed for 24 hours with frequent monitoring of his visual acuity. The plan was to perform optic nerve sheath decompression if his vision did not improve. The vision recovered to 20/25 over the next several days and was 20/20 by 2 weeks. Ultrasound was repeated several times during this

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period and the optic nerve sheath reduced to a diameter of 3.5 mm.

Computed tomography and MRI are exquisite methods to image the optic nerve in its course as it exits the globe until it reaches the chiasm. However, subtle degrees of thickening can be missed. Echography has the advantage of quantifying the nerve thickness and, by means of the 30° test, it is possible to differentiate excess nerve sheath fluid from solid thickening of the sheaths and nerve parenchyma.

Case Study 111. Optic Nerve Sheath Hemorrhage

Pseudotumor cerebri is defined as increased intracranial pressure in the absence of mechanical obstruction to cerebrospinal fluid outflow. These patients are commonly women in the 20-to-mid-40 age group who are obese with a history of headaches. Radiologic imaging studies show normal to undersized ventricles. They are found to have papilledema on clinical examination and may give a history of visual gray-outs or black-outs.34

BA is a 34-year-old moderately obese woman with a 6-month history of increasingly severe headaches and intermittent obscurations of vision in the right eye. Her primary care physician noted bilateral papilledema and referred her to an ophthalmologist.

Ophthalmologic examination documented vision in both eyes of 20/25 and moderate papilledema on fundus evaluation. Visual field studies revealed bilateral blind spot enlargement worse on the right and moderate peripheral constriction. An MRI scan was obtained and no mass lesion was detected. The ventricles were of normal size and the optic nerve diameters were interpreted as qualitatively normal.

Echography was performed and A-scan revealed optic nerve thickness of 4.5 mm OD and 4.98 mm

OS (Fig. 209). A 30° test was performed and was positive for excess sheath fluid bilaterally with reduction OD to 3.48 mm and OS to 3.72 mm (Fig. 210). The diagnosis was felt to be consistent with pseudotumor cerebri and she was referred for optic nerve sheath fenestration because of the visual field defects and increasing amaurotic symptoms.

A change in vision is the most common presenting complaint of patients seeking attention for ocular problems. A good clinical history and examination can clarify most of these, but echography provides a rapid and cost-effective ancillary technique to assist in the workup of less obvious pathology in the globe and orbit.