Systemic hypertension produces pericyte changes in retinal capillaries.

PURPOSE: The purpose of this study was to examine retinal capillaries and their pericytes that previous research suggests to be contractile. A contractile role regulating capillary blood flow may be more apparent when the vasculature is subjected to the stress of systemic hypertension. METHODS: Using ultrastructural morphometry and the myosin subfragment-1 technique, retinal capillaries of normal and hypertensive rats were measured at three different time points, early, intermediate, and late (24, 44, and 68 wk). RESULTS: Hypertensive capillaries seemed to dilate at the early time point (P = 0.002), were constricted at the intermediate time point (P < 0.001), and did not redilate later. Wall thickness was enlarged at all times, pericyte coverage (the ratio of plasma membrane length in contact with the vascular circumference to the outer circumference of the endothelial tube) was greater at early and intermediate time points, and the total area of viable cytoplasm relative to the vessel wall area was increased at the intermediate time (all P < 0.001). Also, at the intermediate time, the circumferential coverage of the endothelial tube by actin filament bundles within pericytes and the actin area relative to the vessel wall area had increased (P < 0.001). CONCLUSIONS: These data indicate that the effects of systemic hypertension extend into the retinal capillary bed, causing pericyte change with actin increase and capillary constriction. They represent the first in vivo indirect evidence by morphologic criteria for pericyte contractility in retinal vascular disease.

Risk factors for high-risk proliferative diabetic retinopathy and severe visual loss: Early Treatment Diabetic Retinopathy Study Report #18.

PURPOSE: To identify risk factors for the development of high-risk proliferative diabetic retinopathy (PDR) and for the development of severe visual loss or vitrectomy (SVLV) in eyes assigned to deferral of photocoagulation in the Early Treatment Diabetic Retinopathy Study (ETDRS). METHODS: Multivariable Cox models were constructed to evaluate the strength and statistical significance of baseline risk factors for development of high-risk PDR and of SVLV. RESULTS: The baseline characteristics identified as risk factors for high-risk PDR were increased severity of retinopathy, decreased visual acuity (or increased extent of macular edema), higher glycosylated hemoglobin, history of diabetic neuropathy, lower hematocrit, elevated triglycerides, lower serum albumin, and persons with mild to moderate nonproliferative retinopathy, younger age (or type 1 diabetes). The predominant risk factor for development of SVLV was the prior development of high-risk PDR. The only other clearly significant factor was decreased visual acuity at baseline. In the eyes that developed SVLV before high-risk proliferative retinopathy was observed, baseline risk factors were decreased visual acuity (or increased extent of macular edema), older age (or type 2 diabetes), and female gender. CONCLUSIONS: These analyses supported the view that the retinopathy-inhibiting effect of better glycemic control extends across all ages, both diabetes types, and all stages of retinopathy up to and including the severe nonproliferative and early proliferative stages and the possibility that reducing elevated blood lipids and treating anemia slow the progression of retinopathy.

Magnetic resonance for evaluation of the thorax.

Evaluation of diseases in the chest by MR is continually evolving. Early studies showed the potential of the technique for imaging the mediastinal and hilar structures and for demonstrating the normal anatomy of the thorax on sagittal, coronal, and transverse MR images. As more data have been compiled, investigators have compared MR to computed tomography for its ability to assess mediastinal and hilar adenopathy and masses, bronchogenic carcinoma and other pulmonary parenchyma lesions, and for assessment of the pulmonary vascularity. MR has been shown in these situations generally to provide equivalent information to that provided by computed tomography. MR, compared to computed tomography, is still in its infancy in regard to the length of time of its availability and in relation to the MR technology for obtaining images. MR is a technique that has wide variation as to type of image quality obtained depending upon the MR system utilized and the pulse sequence utilized. Because of the diverse nature of potential variables for imaging, many times the images are not equal in quality. As a consequence of this significant variability, the data in the literature are divergent on the precise utility of MR. Although the recommended use of MR may change rapidly, the current feeling is that MR should be used as a procedure complementary to computed tomography in those patients with allergy to iodinated contrast material and to aid in defining equivocal lesions as seen on computed tomography, such as small central hilar bronchogenic carcinomas.

Use of linear tomography to confirm the diagnosis of allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) has been recognized increasingly in the past few years. In minimal disease, plain chest films may be insensitive. Early detection of pulmonary involvement may help prevent irreversible damage to the lungs and bronchi. Bronchography, while both sensitive and specific, is not without hazard, particularly to the asthmatic patient. We evaluated the usefulness of linear tomography in confirming ABPA prior to initiation of corticosteroid therapy. We find that tomography is a simple, noninvasive instrument for detecting the presence of or proving the absence of the earliest manifestations of ABPA.

Roentgenographic and clinical staging of allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a disease of asthmatics that follows a protracted course. When ABPA is treated with high dose corticosteroids, it presents a difficult problem in clinical management. Five stages, based on clinical, roentgenographic, and immunologic criteria, have been identified as follows: (I) acute, (II) remission, (III) exacerbation, (IV) corticosteroid-dependent asthma, and (V) pulmonary fibrosis. We studied 24 ABPA patients actively followed for up to 11 years at our institution. We conclude that while there are no unique roentgenographic findings to define a particular stage, clinicoroentgenographic staging does aid in therapeutic management. Two major roentgenographic contributions are (1) to establish the diagnosis by demonstrating proximal bronchiectasis, and (2) to provide a baseline for an individual patient against which to monitor progressive changes and remissions.

Factors influencing response to strabismus surgery.

Based on analyses in a series of 116 patients, we found that the response to strabismus surgery (degrees of change of ocular alignment per millimeter of rectus recession) correlated significantly with the preoperative deviation for esotropic and exotropic patients. The prediction of response to strabismus surgery was not improved significantly with the inclusion of axial length, age, and/or preoperative refractive error beyond the prediction provided with use of only the preoperative deviation, even though we have previously suggested that the response to strabismus surgery should be related to axial length. We believed that larger eyes should have a smaller response for the same number of millimeters of surgery than smaller eyes. We now believe that although the response to strabismus surgery does correlate significantly and inversely with axial length, this correlation may not be clinically important given the much stronger influence of preoperative deviation.

Aging effects on accommodation and outflow facility responses to pilocarpine in humans.

OBJECTIVE: To determine the relationships among age, outflow facility, and refractive and facility responses to pilocarpine in humans. METHODS: Refraction, intraocular pressure, and outflow facility were determined in 30 normal volunteers aged 20 to 75 years, by coincidence refractometry, applanation tonometry, and Schiøtz tonography, respectively, before and 1 hour after a 30-microL drop of 2% or 6% pilocarpine. Simple regression of baseline facility, postpilocarpine facility, and facility change, on age and refractive change singly and jointly, was performed. Stepwise regression models and graphic conditioning plots were used to determine, for each facility variable, its relationship to age or refractive change specifically. RESULTS: Baseline outflow facility and maximum pilocarpine-induced refractive change (ie, accommodation) declined with age, but the decrease in intraocular pressure and the facility response to pilocarpine did not. After adjusting for age, for baseline facility, there was no further relationship to 6% pilocarpine-induced accommodation, and a slight residual relationship to 2% pilocarpine-induced accommodation. After adjusting for both 2% or 6% pilocarpine-induced accommodation, the relationship to age was still significant. The facility increase after 2% or 6% pilocarpine did not depend on age and/or accommodative amplitude. CONCLUSIONS: In humans, as previously described in rhesus monkeys, an age-related loss of ciliary muscle mobility may compromise the basal function of the trabecular meshwork. However, unlike monkeys, humans exhibit no loss of the intraocular pressure or outflow facility response to pilocarpine with age.

Melanocytes and iris color. Light microscopic findings.

OBJECTIVE: To systematically evaluate morphologic differences in iris stroma that contribute to clinically perceptible differences in iris color, using immunohistochemical identification of stromal melanocytes and fluorescence microscopy. METHODS: Paraffin-embedded sections from 51 human irides were stained with S100a and fluorescein isothiocyanate. Cells were counted and scored as melanocytes or other. Melanocyte number, proportion, and density were determined for light-colored (blue), medium-colored (hazel) and dark-colored (brown) irides and compared. RESULTS: No statistically significant difference was observed for mean total cellularity or mean melanocyte number among the three color groups. Mean total stromal cell count was 1177 +/- 259 (mean +/- SEM), and mean melanocyte number was 778 +/- 196 per 5-micrometer section. In human irides, 65.9% of the iris stroma is composed of melanocytes. Melanocyte density (number of cells per square millimeter) is not related to iris color. CONCLUSION: The number of melanocytes, the proportion of melanocytes, and iris stromal cellularity are not major contributors to iris color.

Histopathologic study of eyes after iodine I 125 episcleral plaque irradiation for uveal melanoma.

OBJECTIVES: To describe the histopathologic findings attributable to irradiation in eyes with uveal malignant melanoma treated with iodine I 125 brachytherapy and to compare these findings with those reviewed in a previous study that compared histopathologic findings in eyes enucleated after proton beam teletherapy with those seen in eyes in a nonirradiated control group. METHODS: The slides from 22 eyes with uveal melanoma that had undergone enucleation after the administration of 125I brachytherapy were studied. The histopathologic features of the tumor and the retina were graded. Results were compared with findings from a previously reported group of 47 proton beam-treated eyes and its control group. RESULTS: Patient age, time between irradiation and enucleation, and ciliary body involvement were similar for the 125I brachytherapy-treated group and the proton beam-treated group and its control group. This allows comparison of the histopathologic findings. Comparing the 125I brachytherapy- and proton beam-treated groups, most histopathologic features were similar with nominally statistically significant differences only for cell type, number of mitotic figures, and fibrous metaplasia of the retinal pigment epithelium adjacent to the tumor. CONCLUSIONS: Irradiation of uveal melanoma induces changes in the tumor and in the surrounding retina. Brachytherapy and charged particle therapy are the 2 principal methods of irradiation. This study demonstrates that similar changes are produced by 125I plaque irradiation and proton beam irradiation.

MRI of cardiac pseudoaneurysm and other complications of myocardial infarction.

The purpose of this paper is to review the spectrum of pathology revealed by cardiac magnetic resonance (MR) in the evaluation of myocardial infarction. In addition, the paper is intended to provide a concise introduction to the capabilities and limitations of MR in the evaluation of myocardial infarction and its complications. To provide this introductory guide, three cases of infarction are reviewed in detail, including one unusual case of infarction with both true and false ventricular aneurysm formation. A selected review of the literature is included to demonstrate the current role of MR in the work-up and follow-up of acute infarction.

Feasibility of angle independent Doppler color imaging for in vivo application: preliminary study on carotid arteries.

An experimental system has been used to acquire Doppler color images using a linear transducer from an ultrasound scanner to reconstruct angle independent Doppler color (AIDC) images in normal carotid arteries in 21 volunteers. Images were first taken from relatively straight segments in the common carotid artery, and comparisons were made in a small area at the center stream. At peak systole, the correlation coefficient of the velocity amplitudes between AIDC imaging (AIDCI) and duplex scanning was 0.94; the correlation coefficient between the flow angles measured from AIDCI and the angles of the vessel wall was 0.99. Periodic variations of the flow angle over the cardiac cycle were always observed by AIDCI, whereas the changes in the geometric angle of the vessel itself were insignificant. This observation suggests that the AIDCI technique is sensitive to alterations of flow direction. On the other hand, the deviation of the flow angle from a fixed correction angle in duplex scanning may cause a certain degree of error in velocity determination. AIDC images were also obtained at the carotid bifurcation. The results show that the AIDCI technique is able to depict major flow features, such as velocity skewing, flow separation, flow reversal and vortical flow, in a complex flow field.

Prolapsing inflammatory pseudopolyp-fold complex of the oesophagogastric region.

This article describes a series of 12 adult patients in whom a prominent and mobile polypoid fold of the oesophagogastric region was demonstrated radiologically. Subsequent endoscopic and histopathologic studies confirmed the presence of an inflammatory pseudopolyp at the squamocolumnar junction and contiguous with a thick gastric rugal fold. The clinical and radiographic features of this entity and the mechanisms of its formation are reviewed.

How far can a medial rectus safely be recessed?

Previous studies have suggested that the location of the equator should be important in determining the site of a "safe maximum recession" of a rectus muscle, and that the location of the equator should be a function of axial length. Exactly where in relationship to the equator a muscle can be safely recessed has never been scientifically determined. Over a 4-year period, we measured axial length on all patients we operated on for strabismus. Using a previously derived formula, we were able to calculate the limbus-to-equator distance, given axial length. Based on our analysis of 28 patients in whom we recessed one or both medial recti posterior to the equator, we believe that recessions of the medial recti up to 1.5 mm posterior to the equator should not produce postoperative medial rectus underaction associated with an overcorrection, but recessions that are further than 1.5 mm posterior to the equator may do so. Recessions to a point greater than 11 mm from the limbus do not appear to be associated with late progressive overcorrection provided that the site of recession is not greater than 1.5 mm posterior to the equator. Using our previously determined formula for estimating the location of the equator, given axial length, we have generated easy-to-use reference tables for determining the location of the equator in terms of millimeters posterior to the limbus. Also, based on axial length data from 180 strabismus patients, we have generated an algorithm for predicting axial length, given age, and refractive error, which may be useful to the strabismus surgeon in predicting the location of the equator when A-scan ultrasonography is not available.

Axial length estimation in strabismic patients.

BACKGROUND: Previous studies have indicated that axial length determination is important in strabismic patients for defining the limit for a safe maximum recession of the medial rectus. Also, the response to strabismus surgery may be, in part, a function of axial length. We previously published a formula for predicting axial length based on age and refractive error; however, its accuracy has not been tested in a patient population that is different from the one used to generate the formula. The purpose of this study is to test a formula for estimating axial length, given age and refractive error, in a population that is different from that from which it was generated. METHOD: We measured axial length using A-scan ultrasonography in 163 consecutive patients undergoing strabismus surgery. Twenty-nine patients were younger than 18 months of age; 134 patients were between 18 months and 10 years of age. We compared the measured axial length determination with the axial length value estimated by a formula generated from our previous published series. RESULTS: For patients younger than 18 months of age, the equation estimated axial length within 0.5 mm in 41.4% of patients, within 1.0 mm in 79.3% of patients, and within 1.5 mm in 93.1% of patients. For patients between 18 months and 18 years of age, the formula estimated axial length within 0.5 mm in 37.3% of patients, within 1.0 mm in 73.1% of patients, and within 1.5 mm in 87.3% of patients. CONCLUSIONS: The formula may be useful for the strabismus surgeon in estimating axial length when A-scan ultrasonography is not available in an operating room setting, particularly in congenital esotropes who require larger recessions in small eyes. If, however, A-scan ultrasonography is available, it is preferable to using the formula. The formula is not sufficiently accurate for use for calculating intraocular lens power.