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Biomedical subjects

C J Pavlin

Publications and source records attributed to C J Pavlin.

54 records · Page 3Linked to original sources
PubMed1993

Ultrasound biomicroscopy in the assessment of anterior scleral disease.

High-frequency ultrasound biomicroscopy is a new method of examining subsurface anterior segment structures of the eye at microscopic resolution. The sclera has a high internal reflectivity and can be differentiated from the cornea, and overlying and underlying tissue. Using this modality, we examined 18 patients with various manifestations of scleral disease. Localized anterior staphyloma could be differentiated from other causes of a black spot on the scleral surface. Episcleral thickening could be differentiated from involvement of the sclera itself. Different patterns of scleral involvement could be imaged including diffuse low-reflective mottling, low-reflective nodules extending into the scleral substance, and scleral thinning. Scleral thinning could be assessed and quantified. Underlying changes in the vitreous could be detected. Ultrasound biomicroscopy was a useful adjunct to clinical examination in the assessment of anterior scleral disease.

Adult↗
PubMed1993

An ultrasound biomicroscopic analysis of angle-closure glaucoma secondary to ciliochoroidal effusion in IgA nephropathy.

Immunoglobulin A nephropathy is a common glomerulonephritis of unknown cause. Episcleritis, scleritis, anterior uveitis, and keratoconjunctivitis sicca have been associated with this disease. We diagnosed angle-closure glaucoma secondary to ciliochoroidal effusion in a patient with IgA nephropathy confirmed by biopsy. High-frequency ultrasound biomicroscopy was used to determine internal relationships of angle structures and to follow changes with treatment. Supraciliary effusion undetected by B-scan ultrasound and retinal examination was easily imaged by ultrasound biomicroscopy. Glaucoma mechanisms included forward rotation of the ciliary processes, which caused direct angle closure in a manner similar to plateau iris. Ultrasound biomicroscopy showed that cycloplegia improved this mechanism by retracting the ciliary processes, but angle closure secondary to forward iris bowing from pupil block remained. Iridectomy was performed and immediately opened the angle. Ultrasound biomicroscopy proved a useful method of defining mechanisms and a helpful guide to treatment in this type of glaucoma.

Anterior Eye Segment↗
PubMed1993

Scleral melt after cryotherapy for conjunctival melanoma.

BACKGROUND: The authors report a patient with a cryotherapy-induced scleral melt after combined excision and cryotherapy of a conjunctival melanoma arising within primary acquired melanosis with atypia. FINDINGS: In a 65-year-old white man, a severe scleral melt developed within 1 month of complete excision of a superficial conjunctival melanoma combined with double-freeze-thaw nitrous oxide cryotherapy to the scleral bed and surrounding conjunctival margins. Ultrasound biomicroscopy showed the degree of scleral thinning. CONCLUSIONS: Although many complications associated with cryotherapy have been described in the literature, there are no reports of a scleral melt. Scleral melt is a potential complication of cryotherapy that can occur despite taking precautions and should be monitored in the first few weeks after cryotherapy to the scleral bed of excised conjunctival tumors.

Aged↗
PubMed1993

Determination of haptic position of transsclerally fixated posterior chamber intraocular lenses by ultrasound biomicroscopy.

Transscleral fixation of posterior chamber intraocular lenses has become an increasingly popular procedure in eyes lacking adequate posterior capsular support. The assumption is generally made that these lenses are fixated in the ciliary sulcus. To test this assumption, 17 cases with transsclerally fixated posterior chamber intraocular lenses were examined with ultrasound biomicroscopy, a new method of producing subsurface images in living eyes at microscopic resolution. All lens haptics were easily visualized with this technique. Of 34 haptics in 17 patients, 13 were adequately located in the sulcus region, eight were located posterior to the ciliary processes, and 13 were located anterior to the sulcus region, accompanied by some degree of angle closure. Haptics with a more posterior scleral exit of the suture tended to be located more posteriorly. The cases in which the haptics were located anteriorly had scleral exit points from 1 mm to 2 mm from the limbus. The surgical placement of transsclerally fixated lenses is a blind procedure in most cases. Our series demonstrates the difficulty in reliably placing the haptics in the ciliary sulcus.

Cataract Extraction↗
PubMed1992

Ultrasound biomicroscopy of anterior segment structures in normal and glaucomatous eyes.

We developed a new method of imaging the anterior segment of the eye using high-frequency ultrasound that allows structural details of the angle, iris, ciliary body, zonule, and posterior chamber to be visualized and measured at microscopic resolution in living patients. We applied the term ultrasound biomicroscopy to this technique, which we used to image anterior segment structures in a series of nine normal subjects. We provide a system of definition for anterior segment measurements that will allow reproducible measurements to be performed in the future. Measurements in normal subjects provide a foundation for future studies of specific glaucoma types and facilitate comparison of normal and glaucomatous eyes. Images in several specific types of glaucoma were obtained to exemplify the potential of this technique.

Anterior Eye Segment↗
PubMed1992

Ultrasound biomicroscopy in plateau iris syndrome.

Ultrasound biomicroscopy is a new technique that uses high-frequency ultrasound (50 to 100 MHz) to produce images of the entire anterior segment at high resolution (20 to 50 microns). The iridocorneal angle, iris, ciliary body, and posterior chamber can be imaged in detail and the dimensions and anatomic relationships of these structures determined. Plateau iris syndrome is a condition in which the angle remains appositionally closed or occludable after iridectomy for angle-closure glaucoma. How the iris remains in a position that allows it to occlude the angle has been uncertain. We performed ultrasound biomicroscopy eye examinations on eight patients with clinically diagnosed plateau iris syndrome. In all the patients, ciliary processes were situated anteriorly compared to the position in normal subjects and in patients with angle closure caused by pupillary block. The ciliary processes provide structural support beneath the peripheral iris, preventing the iris root from falling away from the trabecular meshwork after iridectomy.

Anterior Eye Segment↗
PubMed1992

Ultrasound biomicroscopy of anterior segment tumors.

BACKGROUND: Ultrasound biomicroscopy is a new method of imaging the anterior segment of the eye at microscopic resolution using high frequency ultrasound. METHODS: A prospective study was performed to evaluate the use of ultrasound biomicroscopy in imaging anterior segment tumors. Forty-five patients underwent clinical examination followed by slit-lamp photography, anterior segment B-scan ultrasonography, and ultrasound biomicroscopy according to an established protocol. RESULTS: All lesions were clearly imaged by ultrasound biomicroscopy, while only 17 were detectable by conventional B-scan ultrasound. Ultrasound biomicroscopy allowed precise measurement and visualization of subsurface features in small tumors. Differentiation between solid and cystic lesions was easily achieved. The margins of ciliary body tumors could be more accurately defined. Histopathologic correlation was possible in four cases managed surgically. Ultrasound biomicroscopy images compared favorably with low-power microscopy. No complications were encountered. CONCLUSION: Ultrasound biomicroscopy proved a valuable new noninvasive technique in the evaluation of anterior segment tumors.

Anterior Eye Segment↗
PubMed1992

Ultrasound biomicroscopy in glaucoma.

Ultrasound Biomicroscopy is a newly developed high resolution imaging method that uses high frequency ultrasound (50-100 MHz). Tissue penetration is about 4 mm. This method allows detailed observation of anterior and posterior chamber anatomy in the living eye, and is thus a useful tool in both clinical assessment of glaucoma, and research into causes of various glaucoma types.

Anterior Chamber↗
PubMed1991

Clinical use of ultrasound biomicroscopy.

The authors have developed a method of obtaining images of cross-sections of the intact anterior globe at microscopic resolution. High-frequency ultrasound transducers (50-100 MHz) have been developed and incorporated into a clinical B-scan device capable of producing images in the living human eye to a depth of approximately 4 mm at an axial and lateral resolution approaching 20 microns. Clinical use of this instrument is no more difficult than conventional immersion ultrasonography. The authors' results in a series of 14 clinical cases have shown that this method can provide information unavailable from any other imaging technique. Anterior segment tumors difficult to define with conventional ultrasound can be measured and the extent of invasion determined. Differentiation of tissue on the basis of internal acoustic characteristics is aided by the very fine backscatter speckle patterns at these frequencies. Pathology behind anterior segment opacities can be imaged in detail and the ability to image angle structures in cross-section allows a new quantitative method of gonioscopy. The ability to define the relationship of the iris, posterior chamber, zonules, ciliary body, and lens is potentially helpful in understanding mechanisms of glaucoma. Ocular structures can be measured with increased accuracy. Clinical ultrasound biomicroscopy (UBM) has shown significant potential as an aid in diagnoses of ocular disease.

Anterior Eye Segment↗
PubMed1991

Adenoma of the nonpigmented epithelium of the ciliary body.

A 56-year-old man presented with a left ciliary body mass, anterior vitreous hemorrhage and a subluxed, cataractous lens. The clinical course included rapid enlargement of the mass, anterior uveitis, cataract progression and secondary glaucoma. Investigation included fluorescein angiography, ultrasonography and computed tomography. The eye was enucleated because of progressive enlargement with poor vision and uncontrolled secondary glaucoma. Histopathological examination showed an adenoma of the nonpigmented ciliary epithelium with cystic areas of hyaluronidase-sensitive acid mucopolysaccharide. The mass distorted the iris, occluded the angle structures and produced a complete cataract. The basement membrane of the adjacent ciliary processes was extensively thickened. The authors discuss the clinical association with vitreous hemorrhage and the local damage caused by this benign tumour.

Adenoma↗
PubMed1990

Subsurface ultrasound microscopic imaging of the intact eye.

The authors have developed a method of obtaining images of cross sections of the intact eye at microscopic resolution. High-frequency ultrasound transducers (100 MHz) have been developed and incorporated into imaging devices. These devices are capable of producing images to a depth of 4 mm at an axial and lateral resolution approaching 20 microns. Resolution exceeds that of current combined A- and B-scan imaging devices by a factor of approximately 10. Microscopic images of ocular structures including Schlemm's canal, cornea, iris, ciliary muscles, and retina have been produced in eye bank eyes. These studies show the feasibility of developing an apparatus to be used in the clinical setting for examining anterior structures of the eye not visible by current techniques.

Anterior Chamber↗
PubMed1989

Ultrasound determination of the relationship of radioactive plaques to the base of choroidal melanomas.

There is an assumption that radioactive plaques placed at surgery are, and will remain, in proper relationship to the base of the tumor. The plaque dose is calculated based on this assumption. In fact, factors such as loose sutures, improper diameter estimations, pressure from adjacent rectus muscles, and intervening tissue (oblique muscles) can compromise this relationship. Ultrasound provides a practical method of imaging the tumor and plaque simultaneously. The authors have used postoperative ultrasound to monitor the accuracy of iodine-125 plaque placement in nine cases. Detection of eccentrically placed and malpositioned plaques provides valuable insight which can be used to refine surgical technique. Detection of plaque tilting by oblique muscles can serve as a basis for recalculating dosage. The relationship of plaque margins to vital ocular structures such as the optic nerve can also be determined by ultrasound.

Brachytherapy↗
PubMed1984

MR imaging of orbital tumors with CT and ultrasound correlations.

Fourteen patients with various orbital space-occupying lesions were studied by magnetic resonance (MR) imaging with a 0.15 T imager using spin-echo and inversion-recovery pulse sequences. Computed tomographic and ultrasonographic (US) examinations were done in 13 of these patients. All 14 lesions could be demonstrated by MR. Magnetic resonance was found to be better than US but not as good as CT in providing morphological details. Regarding tissue characterization, US was the most useful among the three modalities. With the T2-weighted spin-echo pulse sequence, a possible trend in tissue characterization could be shown. From our preliminary experience, we conclude that MR imaging using a 0.15 T resistive magnet offers no distinct advantage over the combination of CT and US in the diagnosis of orbital tumors.

Adult↗
PubMed1984

Use of electronic spread-sheet programs for intraocular lens power calculation.

Electronic spread-sheet programs are commonly available for all brands of personal computers. Intraocular lens formulas of any desired type are easily entered into these programs with no necessity for programming skill. Advantages include rapid calculation of multiple variables, automatic averaging of results, and a continuing record of all calculations performed.

Computers↗
PubMed1981

Central retinal vein occlusion and scleroderma: implications for sclerodermatous vascular disease.

A patient with scleroderma (progressive systemic sclerosis) who developed central retinal vein occlusion is described. The aetiology of this condition is discussed and the role of possible sclerodermatous vascular disease is highlighted. It is suggested that studies of fundal vasculature could be useful in the clinical assessment of sclerodermatous vascular disease.

Constriction, Pathologic↗
PubMedDate not supplied

An ultrasound biomicroscopic dark-room provocative test.

Ultrasound biomicroscopy can image the relationship of angle structures under any lighting conditions. Eight patients with narrow angles were examined in the light and in the dark. All of the eyes showed iris thickening and shortening, increased anterior convexity of the iris, and varying degrees of angle narrowing in the dark. In one eye, the angle was completely closed. Iridotomy in this patient flattened the iris profile and opened the angle. The degree of angle opening observed after the iridotomy did not change depending on the lighting conditions. Ultrasound biomicroscopy allows imaging of dynamic changes in anterior ocular structures as they occur and provides information regarding angle occludability in the dark.

Aged↗