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Biomedical subjects

C J Pavlin

Publications and source records attributed to C J Pavlin.

At least 37 records · Page 2Linked to original sources
PubMed1997

Ultrasound biomicroscopic imaging of the anterior aspect of peripheral choroidal melanomas.

PURPOSE: To correlate ultrasound biomicroscopic features of the anterior aspect of peripheral choroidal melanoma with respect to histopathology. METHODS: We examined 17 eyes of 17 patients who had clinically diagnosed peripheral choroidal melanomas that approached the ora serrata or extended into the ciliary body and who had been assessed with ultrasound biomicroscopy before enucleation. Comparisons were made between anterior tumor margins imaged by ultrasound biomicroscopy and histopathologic specimens. Anatomic features noted on ultrasound biomicroscopy before enucleation were correlated with enucleation specimens, including supraciliary effusion, rotation of the ciliary body, angle involvement, and internal reflectivity patterns. Anterior tumor margin position was determined with reference to the scleral spur. RESULTS: Mean distances from the anterior tumor margin to the scleral spur were 1.47 mm on ultrasound biomicroscopy and 1.65 mm on pathologic examination. This difference was not statistically significant (P = .325). Tumor features evident on ultrasound biomicroscopy were also seen on pathologic examination: supraciliary choroidal effusions in seven of seven, ciliary body rotation in seven of eight, and angle involvement in seven of eight. All tumors were mixed-cell melanomas, and 12 of 17 (70%) demonstrated homogeneous ultrasound biomicroscopic internal reflectivity. Irregular internal reflectivity was seen in five of 17 tumors (29%) and was related to prominent internal vascularity on pathology in three of five. CONCLUSIONS: Ultrasound biomicroscopy is an accurate imaging technique for the in vivo assessment of anterior tumor margins of peripheral choroidal melanomas and can provide detailed imaging of the tumor's interface with the ciliary body.

Anterior Eye Segment↗
PubMed1997

Supraciliary effusions and ciliary body thickening after scleral buckling procedures.

PURPOSE: The purpose of the study was to use ultrasound biomicroscopy to identify and quantity changes in anterior segment parameters after scleral buckling procedures. METHODS: Ultrasound biomicroscopy was used to examine 15 patients with retinal detachment within 1 week before and after surgery. Quantitative measurements were performed of anterior chamber depth, supraciliary effusion depth, ciliary body thickness, and angle opening. RESULTS: Supraciliary fluid was present after surgery in 12 patients (80%). Average supraciliary fluid depth was 0.16 +/- 0.13 mm. Ciliary body thickness measurements at a point 2-mm posterior to the scleral spur increased after surgery in all patients an average of 0.15 +/- 0.10 mm. There was a strong correlation between ciliary fluid levels and change in ciliary body thickness (r = 0.742, P < 0.01). Anterior chamber depth decreased after surgery in 14 patients (93%). A decrease of angle opening of greater than 5 degrees was noted in 11 patients (73%). In all of these 11 patients, the ciliary body and iris root were considered to be rotated anteriorly. Six (55%) of 11 of these patients showed anterior bowing of the iris, indicating pupillary block. Complete angle closure occurred over one to three quadrants in three patients, but none of these patients had complete angle closure or glaucoma. CONCLUSIONS: Supraciliary effusions and ciliary body thickening are common after scleral buckling procedures and can produce conditions conducive to angle closure. Angle narrowing occurs through a combination of direct anterior iris rotation and induced pupillary block.

Anterior Chamber↗
PubMed1997

Uveitis-glaucoma-hyphema syndrome after handmade, anterior chamber lens implantation.

Two patients developed uveitis-glaucoma-hyphema syndrome secondary to implantation of handmade anterior chamber intraocular lenses (IOLs). The IOLs were designed and made by the patients' ophthalmologists in their native Ukraine. The cases illustrate innovative and unusual solutions to the shortage of quality IOLs in the developing world and the challenging management of patients who present with complications arising from these IOLs.

Adult↗
PubMed1997

Preoperative ultrasound biomicroscopy to assess ease of haptic removal before penetrating keratoplasty combined with lens exchange.

PURPOSE: To evaluate a method of assessing anterior chamber intraocular lens (IOL) haptics before combined penetrating keratoplasty and IOL exchange in eyes with poor corneal clarity resulting from pseudophakic bullous keratopathy (PBK). SETTING: Department of Ophthalmology, Toronto Hospital, Ontario, Canada. METHODS: Twelve eyes (25 haptics) with PBK were studied using ultrasound biomicroscopy (UBM). The degree of haptic encasement was graded. The result was compared with the degree of difficulty and the complications encountered in removing the IOL at the time of surgery. The surgeons were masked as to the UBM results. RESULTS: All haptics were easily visualized with UBM, with 23 in the angle and 2 passing through a peripheral iridectomy. On UBM, 9 haptics were noted to lie free in the angle, and 16 were encased by fibrotic tissue. Eight were covered by less than 100 microns and 8 by more than 100 microns of tissue. Calculations using Kappa statistics found a strong predictive value for the UBM in identifying the presence or absence of fibrotic encasement and degree of difficulty in removing the anterior chamber IOL haptics. Ultrasound biomicroscopy also allowed assessment of the adjacent angle for synechias. CONCLUSION: Ultrasound biomicroscopy provides an alternative method for evaluating anterior chamber IOL haptics when gonioscopy is not possible because of corneal opacity. This method allows the surgeon to predict preoperatively the degree of difficulty that will be encountered in explanting the IOL.

Anterior Chamber↗
PubMed1996

Accommodation and iridotomy in the pigment dispersion syndrome.

BACKGROUND AND OBJECTIVE: Iris concavity has been noted in pigment dispersion syndrome, and could have a role in producing iris-zonule contact. Iris concavity is most likely caused by a relative increase in anterior chamber pressure. The method by which this occurs remains speculative. The authors used ultrasound biomicroscopy to examine the role of accommodation in producing iris concavity and to document changes that occur following iridotomy. PATIENTS AND METHODS: Thirteen patients with clinically diagnosed pigmentary dispersion and pigmentary glaucoma underwent accommodation studies while being continuously imaged with ultrasound biomicroscopy. Anterior chamber depths were measured and iris configuration noted on distance and near fixation. These studies were repeated in 6 patients following laser iridotomy. RESULTS: All patients showed a decrease in anterior chamber depth with accommodation. Ten patients had a planar iris configuration on distance fixation and 3 concave. Eleven of 13 patients showed increased concavity of the iris on near fixation as compared with distance fixation. Following iridotomy in 6 patients, the iris showed a planar configuration that remained unchanged on near fixation. CONCLUSION: Accommodation increases iris concavity in some patients with pigment dispersion syndrome. The most likely explanation is an accommodation-induced relative increase in anterior chamber pressure secondary to anterior movement of the lens surface. Iridotomy prevents change in the iris profile with accommodation.

Accommodation, Ocular↗
PubMed1996

Diagnosis of traumatic cyclodialysis by ultrasound biomicroscopy.

BACKGROUND AND OBJECTIVE: To evaluate the ability of high-frequency ultrasound biomicroscopy to diagnose traumatic cyclodialyses not evident on clinical examination. PATIENTS AND METHODS: Six eyes to six patients with posttraumatic hypotony and/or shallow anterior chamber and suspected cyclodialysis clefts were examined with slit-lamp biomicroscopy, gonioscopy, B-scan ultrasonography, and ultrasound biomicroscopy. Ultrasound biomicroscopy provided high resolution of cross-sectional images of the anterior chamber angle, posterior chamber, and anterior uveal tissue. RESULTS: Ultrasound biomicroscopy confirmed the disinsertion of the ciliary body from the scleral spur and associated ciliary body detachment in all eyes. Gonioscopy failed to demonstrate a cyclodialysis cleft in five eyes because of hyphema (two eyes) and abnormal iris architecture (related to trauma) precluding visualization of the angle recess (three eyes). Using information from ultrasound biomicroscopy imagining, one patient underwent a ciliary body reattachment procedure and repair of the cyclodialysis cleft. CONCLUSION: Ultrasound biomicroscopy is a noninvasive method that can accurately diagnose the presence of traumatic cyclodialyses and can aid in surgical management. It is particularly useful in the presence of hazy media, hypotony, and/or abnormal anterior segment anatomy.

Adolescent↗
PubMed1995

Ultrasound biomicroscopic imaging of the effects of YAG laser cycloablation in postmortem eyes and living patients.

PURPOSE: The authors performed a series of experiments designed to determine if early effects of YAG laser cycloablation could be detected by ultrasound biomicroscopy in postmortem eyes and living patients. They also designed an apparatus that allowed simultaneous ultrasound biomicroscopic imaging of YAG laser cycloablation. METHODS: Treated and untreated regions of postmortem eyes treated with YAG cycloablation were imaged and compared. Treatment was placed at varying distances from the limbus in postmortem eyes and the resulting effects imaged. Histologic examinations were performed after imaging. Six living patients had ultrasound biomicroscopy before and after YAG cycloablation. An apparatus combining contact YAG laser and ultrasound biomicroscopy was used in postmortem eyes. RESULTS: Early treatment effects imaged included ciliary epithelial disruption, ciliary epithelial separation, and bubble formation. Ultrasound biomicroscopic findings varied with the distance of treatment from the limbus and were maximal below the treatment site. Results of histologic examination showed close correlation to the ultrasound biomicroscopic images. Similar findings to those found in postmortem eyes were found in living patients after treatment. The apparatus combining contact YAG and ultrasound biomicroscopy allowed realtime imaging of effects of YAG laser cycloablation. CONCLUSIONS: The ability of ultrasound biomicroscopy to detect changes associated with cyclodestructive procedures potentially could provide us with a method of improving treatment precision and correlating treatment effect with clinical response.

Cadaver↗
PubMed1995

Ultrasound biomicroscopic features of spherophakia.

BACKGROUND: Spherophakia is an uncommon diagnosis. This is the first case report of spherophakia evaluated by ultrasound biomicroscopy. METHODS: Ultrasound biomicroscopy is a new diagnostic technique developed by one of the authors and provides images with microscopic resolution of the anterior segment. A patient with spherophakia was evaluated by ultrasound biomicroscopy (Zeiss-Humphrey, 50MHz) before and after YAG laser iridotomy. RESULTS: Ultrasound biomicroscopic assessment revealed a shallow anterior chamber, a very steep anterior lens curvature, iridolenticular contact, elongated zonules, and an increased distance between the lens equator and the ciliary processes. Angle closure glaucoma was due to a pupil block mechanism. The pupil block was relieved by YAG laser iridotomy. CONCLUSIONS: Ultrasound biomicroscopy is a useful technique to confirm the diagnosis of spherophakia. The pupil block in spherophakia is relieved by YAG laser iridotomy.

Adult↗
PubMed1995

Practical application of ultrasound biomicroscopy.

It is beyond the scope of this article to comment in detail on every condition in which ultrasound biomicroscopy has provided useful information. Details of the use of this method in clinical conditions are provided in the references cited. Ultrasound biomicroscopy has given us a new way of looking at disease in the living eye. We can now observe the interrelationships and movement of structures that previously could not be imaged. Future theoretic and technologic advances should expand the usefulness of this imaging method.

Anterior Eye Segment↗
PubMed1994

Malignant glaucoma. Clinical and ultrasound biomicroscopic features.

PURPOSE: To determine conditions associated with malignant glaucoma and to assess anterior segment structures in malignant glaucoma using ultrasound biomicroscopy. METHODS: Over a 3-year period, 14 eyes from 14 patients with malignant glaucoma were evaluated. RESULTS: Of the 14 eyes, 7 received medical therapy alone and 7 required both medical and surgical intervention. Predisposing factors included trabeculectomy in 12 eyes, chronic angle-closure glaucoma in 10, sudden ocular decompression in 2 (1 from suture lysis and 1 from corneal perforation), pseudoexfoliation in 4, and cessation of aqueous suppressants and cycloplegics in 2. Ultrasound biomicroscopy of two eyes showed a shallow supraciliary fluid level, anterior rotation of ciliary processes, and obstruction of the trabeculectomy osteum. CONCLUSIONS: Malignant glaucoma is associated with glaucoma surgery, chronic angle-closure glaucoma, pseudoexfoliation, sudden ocular decompression, and cessation of aqueous suppressants. On ultrasound biomicroscopy, a low supraciliary fluid level was found in two patients.

Aged↗
PubMed1994

Ultrasound biomicroscopic analysis of haptic position in late-onset, recurrent hyphema after posterior chamber lens implantation.

Late-onset, recurrent hyphema is an uncommon complication of posterior chamber intraocular lens implantation. Pathological studies and indirect clinical evidence, including iris transillumination defects and iris tucking, have implicated haptic-iris contact. The technique of high-resolution ultrasound biomicroscopy developed in our laboratories allows imaging of intraocular lens haptics and their relationship to surrounding structures. Examination of two cases with late-onset, recurrent hyphema revealed that the margins of the superior haptics were sulcus fixated and indenting the peripheral iris. Blood could be traced beneath the peripheral iris in one case. Our findings indicate that haptic-iris contact was the source of bleeding. Capsular fixation should make this complication less likely.

Aged↗
PubMed1994

Ultrasound biomicroscopic assessment of the cornea following excimer laser photokeratectomy.

Excimer laser photokeratectomy is used as a refractive tool and in the treatment of superficial corneal disease. Ultrasound biomicroscopy is a new method of ultrasound imaging developed in our laboratories that allows subsurface imaging of ocular structures at microscopic resolution. We used this imaging method to examine 12 patients following excimer laser keratoablation. Following treatment, the normal appearance of a highly reflective Bowman's membrane below the epithelial echo was absent in the treatment zone. Corneal thinning was also noted. Postoperative scarring in the treatment area could be imaged as highly reflective regions in the superficial stroma. In therapeutic cases, corneal opacities could be imaged pretreatment and their depth assessed. The degree of opacity removal could be analyzed post-treatment. Ultrasound biomicroscopy helped assess corneal changes secondary to excimer laser photokeratectomy.

Cornea↗
PubMed1994

Ultrasound biomicroscopic features of pigmentary glaucoma.

We have developed a device capable of producing subsurface images in eyes at microscopic resolution. We call this method "ultrasound biomicroscopy." We examined 19 patients with pigmentary glaucoma or pigmentary dispersion syndrome using ultrasound biomicroscopy. Ten patients were found to have concave irides with small distances between the back of the iris and the zonule. In these patients iris-lens contact was greater than in patients without iris concavity and healthy patients. Nine patients did not show iris concavity or increased iris-lens contact. The finding of iris concavity and increased iris-lens contact is compatible with a theory of reverse pupil block producing intermittent iris-zonule touch, with a valve effect preventing posterior flow of aqueous. This theory was supported by the loss of concavity following iridotomy in three patients. The force that produces a reversal of the normal pressure gradient remains unclear, but recent evidence suggests that accommodation plays a major role. The patients who did not show iris concavity and increased iris-lens contact may have been examined at a time when these forces were not acting or had ceased to act.

Adult↗