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Biomedical subjects

M B Shields

Publications and source records attributed to M B Shields.

At least 73 records · Page 4Linked to original sources
PubMed1991

Intraocular pressure response to the replacement of pilocarpine or carbachol with echothiophate.

In 20 patients with open-angle glaucoma in aphakia or pseudophakia whose intraocular pressure had remained uncontrolled on their current medical therapy, the medication was changed from pilocarpine or carbachol to echothiophate iodide. In all, 12 patients (60%) showed a statistically significant improvement in pressure control, 7 (35%) showed no change, and 1 had higher pressure. One-third of the patients with improved intraocular-pressure control eventually required laser or incisional surgery after a mean of 23 months, whereas the remaining subjects were controlled for the duration of the follow-up, which averaged 26 months. Side effects encountered during echothiophate iodide treatment included ocular irritation, decreased vision, and one retinal detachment.

Aphakia↗
PubMed1991

A 3-month comparison of 1% and 2% carteolol and 0.5% timolol in open-angle glaucoma.

Carteolol, a nonselective beta-adrenergic antagonist with intrinsic sympathomimetic activity, was compared in 1% and 2% topical solutions with 0.5% timolol in 105 patients with primary open-angle glaucoma. In this double-masked, randomized 3-month trial, all three preparations significantly lowered intraocular pressure throughout the study, with no significant differences being observed. There were also no significant differences among the three preparations with regard to ocular or systemic adverse reactions, including heart rate and blood pressure.

Administration, Topical↗
PubMed1991

Glaucoma and Peters' anomaly. A clinicopathologic case report.

A 26-year-old black woman with Peters' anomaly who had been followed since early childhood developed an open-angle form of glaucoma, which required filtering surgery. Light and electron microscope studies of the trabeculectomy specimen, which was obtained by en bloc resection of the trabecular meshwork and iridectomy specimen, revealed that the structures of the anterior-chamber angle were grossly normal aside from evidence of premature aging on the basis of abundant broad-banded collagen fibers in the trabecular lamellae.

Adult↗
PubMed1991

Association of Vistech contrast sensitivity and visual field findings in glaucoma.

Single eye visual fields and contrast sensitivity were assessed in 60 subjects, who were being followed up in a glaucoma clinic for manifest glaucoma or a suspicion of glaucoma because of raised intraocular pressure. The Fieldmaster 5000 (static/kinetic perimeter) was used for the visual fields, and a Vistech wall chart sine wave grating test was used for contrast sensitivity measurements. The subjects were divided into three groups--defect (D), suspect (S) and normal (N)--on the basis of their perimetric findings by subjective grading of 16 perimetric scoring categories for each visual field. The mean Vistech sensitivity levels were not found to be significantly different between the D, S, and N field subgroups at any of the five spatial frequencies provided on the test charts (1.5, 3, 6, 12, and 18 cycles per degree). Complex algorithms combining results from two or more spatial frequencies also failed to yield any significant differences between the groups. Diagnostic sensitivity and specificities relating Vistech contrast sensitivity findings to groups N and D never concomitantly exceeded 60%.

Adult↗
PubMed1991

Early intraocular pressure response to laser trabeculoplasty 180 degrees without apraclonidine versus 360 degrees with apraclonidine.

Early postoperative intraocular pressure elevation (IOP) is less common after 180-degree than after 360-degree argon laser trabeculoplasty (ALT). We retrospectively reviewed the charts of 38 patients treated with 360-degree ALT and perioperative 1% apraclonidine, and those of 39 patients treated with 180-degree ALT without apraclonidine, to determine whether apraclonidine offset the increased risk of transient pressure elevation following 360-degree treatment, as compared with that after 180-degree therapy. The average IOP change and the frequency of pressure elevations at 1 hour, 1 day, and 1 month postoperatively were similar in the two groups. With respect to early postoperative IOP elevation, 360-degree ALT with perioperative apraclonidine appears to be as safe as 180-degree ALT without apraclonidine.

Adrenergic alpha-Agonists↗
PubMed1991

Early postoperative prognostic indicators following trabeculectomy.

We compared prognostic indicators manifesting within the first 2 postoperative days, with filtration status 3 months following trabeculectomy in 51 primary open-angle glaucoma patients. Patients with an avascular area in the filtering bleb 2 days after surgery had a significantly lower (P less than .05) intraocular pressure (IOP) (12.6 mm Hg) 3 months postoperatively than patients with vascular blebs (16.3 mm Hg). However, neither the height, breadth, or transparency of the filtering bleb, presence of microcysts, anterior chamber depth, nor IOP during the first 2 postoperative days were related significantly to the filtration status at 3 months.

Female↗
PubMed1990

Limbal-based vs fornix-based conjunctival flaps in combined extracapsular cataract surgery and glaucoma filtering procedure.

Extracapsular cataract extractions and posterior chamber intraocular lens implantations combined with glaucoma filtering procedures were done in 47 eyes of 43 consecutive patients who had coexisting cataract and glaucoma. A limbal-based conjunctival flap was used in 22 patients and a fornix-based flap was used in 25 patients; the surgical technique was otherwise identical in all patients. Patients were followed up for a minimum of six months (mean, 18 months). Long-term intraocular pressure control and visual acuity were similar in the two groups, although the limbal-based group had significantly better early postoperative intraocular pressure control. Because control of intraocular pressure during the early postoperative period is a principal benefit of combined cataract and glaucoma surgery, we prefer the limbal-based conjunctival flap.

Aged↗
PubMed1990

Comparison of transscleral neodymium:YAG cyclophotocoagulation with and without a contact lens in human autopsy eyes.

A contact lens designed to facilitate neodymium:YAG transscleral cyclophotocoagulation was evaluated on human autopsy eyes, and the lesions produced were compared to the lesions produced by similar laser treatments without a lens. Using the thermal mode at 20-msec duration, the variables studied were distance from the corneoscleral limbus (0.5, 1.5, 2.5 mm); energy (2, 4, 6, 8 J); and offset (distance between the focal points of the aiming and therapeutic beams; settings of 5, 7, 8, 9). By gross and light microscopic inspection, the ciliary body lesions produced were similar with or without the lens. A distance between 0.5 and 1.5 mm appears optimal for damaging the pars plicata. Energies of 4 to 8 J produced ciliary epithelial destruction.

Ciliary Body↗
PubMed1990

Hemianopic offsets in the visual field of patients with glaucoma.

In 359 glaucoma patients (600 eyes), we measured the peripheral field with kinetic targets and the central 30 degrees field of vision with static testing, using the Field-master-5000 automated perimeter to evaluate the prevalence and significance of step-like visual-field defects along the vertical midline (a hemianopic offset). In all, 129 eyes of 121 patients had a hemianopic offset. In 108 eyes the offsets (involving either the peripheral or the central field or both) were associated with other glaucomatous field changes, whereas 21 eyes showed a peripheral offset as an isolated finding. Of the 8 cases of offsets found in both eyes, 7 were binasal and 1 occurred bitemporally but in separate hemifields. This study suggest that hemianopic offsets occur commonly in glaucoma patients but have limited diagnostic value because most are associated with other glaucomatous field changes. However, these findings help in distinguishing glaucomatous offsets from those caused by neurological lesions.

Glaucoma↗
PubMed1990

Evaluation of a protocol for transscleral neodymium: YAG cyclophotocoagulation in one hundred patients.

One hundred consecutive patients with intractable glaucoma underwent transscleral neodymium: YAG (Nd:YAG) cyclophotocoagulation using a standard protocol derived from a study of human autopsy eyes, and were followed prospectively for a minimum of 6 months. After the first treatment, 51 patients had a final intraocular pressure (IOP) between 7 and 20 mmHg (classified as "IOP success") and 17 more had an IOP less than 7 mmHg or more than 20 mmHg, but required no additional surgery ("qualified IOP success"). With one or more additional treatments, the totals rose to 65 IOP successes and 30 qualified IOP successes. Parameters associated with qualified success and failure were younger age and higher preoperative IOP. Forty-five patients in the cumulative IOP success and qualified IOP success groups had reduced visual acuity, although this could be attributed to other ocular problems in at least one half of the cases. Other postoperative complications included transient IOP rise in 23 patients, severe pain in 12 patients, and severe inflammation in 29 patients.

Adolescent↗
PubMed1990

Early tissue response to transscleral neodymium: YAG cyclophotocoagulation.

Transscleral cyclophotocoagulation was performed with a neodymium: YAG laser on five patients 24-72 hr before enucleation for a blind, painful eye. The thermal mode at 20 ms and a maximum offset between aiming and therapeutic beams were kept constant. Variable parameters evaluated were energy levels between 2 and 8 J and distance from the limbus of 0.5-3.0 mm. Because of the underlying distortion in three of the eyes, meaningful interpretation by light microscopic evaluation was possible only in the other two. This suggested that the early histologic hallmark of the procedure is similar to that previously observed in human autopsy eyes with ciliary epithelial damage and elevation from underlying tissue. In addition, fibrin and scant inflammatory cells were seen in the space between ciliary epithelium and stroma. Minimal damage was observed in the ciliary muscle. These findings suggest that direct damage to the ciliary epithelium is the most likely mechanism of reduced aqueous production by this cyclodestructive procedure. The findings also support the concept that an anterior placement of approximately 1.0-1.5 mm posterior to the limbus is most likely to damage the ciliary epithelium of the pars plicata.

Ciliary Body↗
PubMed1989

Risk factors for the development and severity of glaucoma in the pigment dispersion syndrome.

The medical records of 93 patients with pigmentary glaucoma and 18 patients with pigment dispersion syndrome were studied with regard to factors associated with the presence and severity of secondary glaucoma within this population. Male gender, black race, severe myopia, and Krükenberg spindles were identified as possible risk factors. Men were predominant in this population 75 (67.6%); the diagnosis was made in men at an earlier age; they had a higher proportion in the glaucoma group; and they required more aggressive glaucoma therapy. There were only four black patients, but all required surgery. Patients in the glaucoma group had significantly more severe myopia and a higher incidence of Krükenberg spindles. These risk factors may help to identify which patients with the pigment dispersion syndrome require closer follow-up or the possible initiation of prophylactic therapy.

Adolescent↗
PubMed1989

An evaluation of the Tono-Pen for the measurement of diurnal intraocular pressure.

We evaluated the Oculab Tono-Pen for potential value in the measurement of diurnal intraocular pressure. Repeated recordings every ten minutes on the same eyes suggested that the instrument provides reproducible information. However, comparisons with Goldmann applanation tonometric measurements, in both single determinations and eight-hour diurnal recordings, showed considerable variation. Correction factors, using either the mean difference in paired readings from the single measurement study or individual differences from the initial set of diurnal recordings, did not eliminate this lack of correlation between measurements with the two instruments.

Circadian Rhythm↗
PubMed1989

Accuracy of topographic measurements with the Optic Nerve Head Analyzer.

We used a plastic model of the human eye to study the accuracy with which the Optic Nerve Head Analyzer estimates the surface contour and two-dimensional size of the optic nerve head. Computer-generated contour lines were similar to the actual cross-sectional contour of plastic cups as photographed by scanning electron microscopy. The magnification error of computer-measured cup diameters was inversely related to the axial length of the model. The slope of this relationship was reduced with the use of either refraction or axial length as a correction factor for magnification error. Of the two correction factors, the former provided the closest estimation of the known diameters in the phakic model, while the latter performed better in the aphakic model.

Computer Graphics↗
PubMed1989

Automated kinetic perimetry with two peripheral isopters in glaucoma.

An automated perimeter (Fieldmaster 5000) was used to measure the central 30 degrees of vision with static targets (suprathresholding with quantification of defects) and the peripheral visual field with two kinetic stimuli in 599 eyes of 362 patients with glaucoma or a suspicion of glaucoma. The purpose of the study was to compare the additional information gained by measuring the peripheral visual field with two isopters against the time required for this extra examination. The peripheral visual field supported the diagnosis made by central testing in approximately one fourth of all eyes and added additional diagnostic information in another quarter of the cases. In 7% of the total population, or 11% of eyes with abnormal fields, a normal central field was associated with a glaucomatous peripheral defect. Half of the latter eyes had corresponding glaucomatous optic disc changes. The more sensitive isopter uncovered the vast majority of the peripheral field defects. Measurement of each isopter accounted for 22% of the total testing time.

Automation↗