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Biomedical subjects

M B Shields

Publications and source records attributed to M B Shields.

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

Efficacy of autologous blood injection for treating overfiltering or leaking blebs after glaucoma surgery.

PURPOSE: To evaluate the efficacy of autologous blood injections for treating overfiltering or leaking blebs after glaucoma surgery. METHOD: Retrospective review of ten eyes of ten patients who received intrableb autologous blood injections for hypotonous maculopathy. RESULTS: After intrableb blood injection, average intraocular pressure increased from 4.3 mm Hg to 6.4 mm Hg, and average visual acuity improved from 20/88 to 20/77. These results, however, were not statistically significant. CONCLUSION: Our results with autologous blood injection are less favorable than those of previous reports, although further study with a larger case series is needed.

Adult↗
PubMed1997

Argon vs diode laser trabeculoplasty.

PURPOSE: To compare the efficacy of diode laser and argon laser trabeculoplasty in a randomized prospective study of 11 paired fellow eyes. METHODS: Fellow eyes of 11 patients, having had no prior laser trabeculoplasty and requiring laser trabeculoplasty to lower intraocular pressure, were randomly assigned prospectively to diode laser trabeculoplasty in one eye and argon laser trabeculoplasty in the other eye. RESULTS: In the diode laser group, the average baseline intraocular pressure was 21.6 +/- 2.0 mm Hg before trabeculoplasty and 19.6 +/- 2.1 mm Hg (or a 7.7% +/- 11.5% mean pressure reduction) at 1 month, 19.3 +/- 2.6 mm Hg (or a 6.9% +/- 13.5% mean reduction) at 2 months, and 19.0 +/- 3.3 mm Hg (or a 2.4% +/- 16.9% mean reduction) at 3 months postoperatively. In the argon laser group, the average intraocular pressure was 24.4 +/- 3.5 mm Hg before treatment and 17.6 +/- 1.7 mm Hg (or a 24.7% +/- 11.4% mean pressure reduction) at 1 month, 16.8 +/- 2.5 mm Hg (or a 26.7% +/- 15.3% mean reduction) at 2 months, and 15.5 +/- 1.2 mm Hg (or a 30.0% +/- 16.5% mean reduction) at 3 months after laser trabeculoplasty. The difference between argon and diode laser intraocular pressure reduction was statistically significant at 1 month (P < .01), 2 months (P < .01), and 3 months (P < .05) after treatment. CONCLUSION: Argon laser trabeculoplasty appears to be more effective than diode laser therapy in lowering intraocular pressure during the first 3 months after treatment.

Aged↗
PubMed1997

Clinicopathologic features and surgical management of dissecting glaucoma filtering blebs.

Three patients are described in whom full-thickness glaucoma filtering procedures were complicated by marked extension of the bleb over the cornea, with subsequent symptoms that required surgical intervention. The surgical management in each case involved blunt dissection of the bleb from the cornea, with revision of the remaining portion of the bleb differing in each case according to the intraoperative findings. Light microscopic examination of one surgical specimen revealed a markedly attenuated epithelium covering hydropic corneal stroma. The authors postulate that the mechanism of formation involves aqueous humor dissection between corneal epithelium and stroma, leading to abnormal hydration of the superficial lamellae.

Aged↗
PubMed1997

A comparison of intraocular pressure measurements with the XPERT noncontact tonometer and Goldmann applanation tonometry.

PURPOSE: The purpose of this study was to compare intraocular pressure measurements obtained with XPERT, an upgraded model of the noncontact tonometer, with those from Goldmann applanation tonometry. METHODS: An average of three intraocular pressure measurements, generated by the XPERT, was compared with a single reading from a Goldmann applanation tonometer in 421 eyes of 220 patients. RESULTS: The standard deviation of the matched-pair differences (Sdiff) for the entire population was 2.3 mm Hg, whereas in a subset of 95 eyes with intraocular pressures of > or = 20 mm Hg by Goldmann applanation tonometry, the Sdiff was 3.3 mm Hg. CONCLUSIONS: The XPERT was found to provide reliable intraocular pressure measurements, especially within the normal range.

Adult↗
PubMed1997

Physicians' guide to interactions between glaucoma and systemic medications.

PURPOSE: To develop a Physicians' Guide to assist clinicians in the concomitant use of glaucoma and systemic medications. METHODS: The records of 100 consecutive patients with chronic open-angle glaucoma were retrospectively studied to determine the most common systemic medications that are prescribed in this population. The ten most common drug classes were then used to construct a guide to potential interactions and side effects when these medications are used concomitantly with glaucoma drugs. RESULTS: Eighty-four patients were receiving 1 or more medications (a mean of 3.5) for a mean of 2.6 systemic conditions. Systemic antihypertensive agents was the most common class of drugs, being used by 48 patients. Aspirin, the most common single systemic drug, was being used by 25 patients. CONCLUSIONS: A high percentage of patients with chronic open-angle glaucoma receive a wide variety of medications for coexisting systemic disorders. The concomitant use of glaucoma and systemic medications creates the potential for drug interactions, as well as side effects for both groups of drugs, for which the Physicians' Guide may be beneficial.

Adrenergic beta-Antagonists↗
PubMed1996

Retinal vein occlusion after trabeculectomy with mitomycin C.

PURPOSE: To evaluate acute retinal vein occlusion as a potential complication of trabeculectomy with mitomycin C in cases of advanced glaucoma. METHODS: The records of three patients who developed retinal vein occlusions immediately after uncomplicated trabeculectomy with mitomycin C were reviewed. RESULTS: All three patients had advanced open-angle glaucoma with total cupping of the optic nerve, severe visual field loss, and evidence of systemic vascular disease. A marked decrease in intraocular pressure was noted in the postoperative period in all of the patients. CONCLUSION: A shift in the lamina cribrosa, associated with the perioperative intraocular pressure change, may have contributed to occlusion of the venous outflow system in these susceptible patients.

Aged↗
PubMed1996

Apraclonidine 0.5% versus 1% for controlling intraocular pressure elevation after argon laser trabeculoplasty.

BACKGROUND AND OBJECTIVE: Topical apraclonidine hydrochloride 1% is effective for controlling the intraocular pressure (IOP) rise following argon laser trabeculoplasty (ALT). The 0.5% formulation has recently become available commercially. The objective of this study was to compare the efficacy of these two concentrations for controlling IOP after ALT. PATIENTS AND METHODS: All patients undergoing ALT were prospectively randomized to receive either 1% or 0.5% apraclonidine 1 hour before and immediately after the laser surgery. IOP was measured before and 2 and 24 hours after the treatment. RESULTS: No statistically significant difference in mean IOPs was found between the two treatment groups at any time. CONCLUSION: These data suggest that 0.5% and 1% apraclonidine are equally effective for preventing IOP rise after ALT.

Administration, Topical↗
PubMed1996

Histology of conjunctival vascular endothelium after filtering surgery with mitomycin C in rabbits.

OBJECTIVE: To examine histologic changes in conjunctival vasculature during the first 72 hours following filtering surgery with adjunctive mitomycin C in rabbits. DESIGN: Thirty-six New Zealand white rabbits underwent unilateral posterior lip sclerectomy. In 18 rabbits mitomycin C (0.5 mg/mL) was applied subconjunctivally for 5 minutes. The remaining 18 animals were treated with the phosphate-buffered saline vehicle for 5 minutes. Three rabbits from either group were killed at 0, 4, 12, 24, 48 and 72 hours postoperatively. OUTCOME MEASURES: Degree of vascularity of filtering blebs on gross examination and appearance of conjunctival vascular specimens on light and transmission electron microscopy, as assessed by three masked observers. RESULTS: On gross examination the filtering blebs in the mitomycin C group were slightly less hyperemic than those in the control group at 12, 24 and 48 hours and were markedly less hyperemic at 72 hours. Light microscopy showed tightly packed erythrocytes within the conjunctival vessels of the experimental blebs and an almost total absence of endothelium within many of the vascular channels by 72 hours. Transmission electron microscopy showed focal loss of vascular endothelial cells and thrombus formation in the experimental blebs, as early as 12 hours postoperatively. CONCLUSIONS: Our findings suggest that the decreased vascularity of filtering blebs observed after trabeculectomy with adjunctive mitomycin C is at least partially due to a toxic effect of the agent on the endothelial cells of the conjunctival vessels.

Animals↗
PubMed1996

Factors associated with visual acuity loss after noncontact transscleral Nd:YAG cyclophotocoagulation.

PURPOSE: To determine the factors associated with visual acuity loss following transscleral Nd:YAG cyclophotocoagulation (TYC). METHODS: The authors retrospectively studied 479 patients followed for a mean of 22 months after the initial TYC in one eye and analyzed the data with univariate and multivariate analysis for the factors associated with visual acuity loss. Data analyzed included age, race, sex, preoperative intraocular pressure (IOP) and visual acuity, type of glaucoma, total energy per treatment, number of retreatments, final IOP, and duration of follow-up. RESULTS: The preoperative factors associated with visual acuity loss after TYC as determined by both univariate and multivariate analysis were neovascular glaucoma (p = 0.001, odds ratio = 2.80) and black race (p = 0.044, odds ratio = 1.67). Postoperative hypotony and follow-up of > 6 months were also associated with visual acuity loss (p < 0.001, odds ratio = 6.68 and p = 0.046, odds ratio = 2.61, respectively). CONCLUSIONS: Transscleral Nd:YAG cyclophotocoagulation is associated with a greater risk of visual acuity loss in patients with neovascular glaucoma and in the black population. Postoperative hypotony is associated with a poor visual outcome, whereas the association with longer follow-up duration suggests that other factors, related to the patient's underlying disease, are also significant factors.

Adolescent↗
PubMed1995

Noncontact transscleral Nd:YAG cyclophotocoagulation for glaucoma after penetrating keratoplasty.

PURPOSE: To evaluate the effect of noncontact transscleral Nd:YAG cyclophotocoagulation for refractory glaucoma after penetrating keratoplasty on intraocular pressure, visual acuity, and graft status. METHODS: We reviewed the records of all patients treated at the Duke University Eye Center between 1988 and 1993 who had noncontact transscleral Nd:YAG cyclophotocoagulation for uncontrolled glaucoma associated with penetrating keratoplasty. RESULTS: One eye each of 39 patients was included in the study. At final follow-up, ranging from three to 63 months (mean, 27 +/- 18 months), the average decrease in intraocular pressure was 15 mm Hg (P = .001). Thirty-one patients (77%) had a final intraocular pressure between 7 and 21 mm Hg. The number of medications was reduced by an average of 1.4 (P = .0001). Five patients (13%) showed an improvement in best-corrected visual acuity at final follow-up; 12 (31%) maintained stable acuity, and 22 (56%) demonstrated a- deterioration in acuity. Of 25 patients with clear grafts before cyclophotocoagulation, 11 (44%) had graft decompensation. CONCLUSIONS: Noncontact transscleral Nd:YAG cyclophotocoagulation is effective in lowering intraocular pressure in eyes with refractory glaucoma and associated penetrating keratoplasty, although loss of visual acuity and graft decompensation remain important concerns. Further study is needed of other cyclophotocoagulation protocols and alternative treatments for this patient population.

Adult↗
PubMed1995

Variability of contact transscleral neodymium:YAG cyclophotocoagulation.

PURPOSE: To study the variability of ciliary body lesions created by contact Nd:YAG cyclophotocoagulation and to evaluate modifications in probe design to reduce this variability. METHODS: Contact transscleral Nd:YAG cyclophotocoagulation was performed on fresh, enucleated porcine eyes in three ways: using a standard, handheld fiber-optic probe (98 eyes); using the same probe with an adjunctive contact lens guide to control for probe pressure, angle, and position (69 eyes); and using a spring-loaded handpiece to control for probe pressure (148 eyes). Four laser lesions were created in each eye and were rated for size and severity of tissue response. RESULTS: For the three groups of eyes, the mean for size differences (largest lesion minus smallest lesion in millimeters for each eye) was 2.53, 1.65, and 2.36, respectively. The mean for severity differences (most severe lesions minus least severe lesion for each eye, based on a four-part subjective rating) was 1.9, 1.1, and 1.7, respectively. These measures of size difference and severity difference were significantly lower with the lens guide than with the other two systems (P = 0.022 and P = 0.020, respectively). CONCLUSIONS: These findings indicate that contact transscleral cyclophotocoagulation can be associated with considerable variation in the size and severity of the ciliary body reaction. This variation has a significant dependence on probe pressure and orientation against the eye and can be reduced by modification in probe design.

Animals↗
PubMed1994

Videographic and histologic comparison of Nd:YAG and diode laser contact transscleral cyclophotocoagulation.

We performed contact transscleral cyclophotocoagulation in two human autopsy eyes with continuous-wave Nd:YAG and diode lasers. Duration of exposure was two seconds, and powers were 4 to 7.3 W with the Nd:YAG laser and 1.75 to 2.5 W with the diode laser. In both procedures, we used hand-held quartz fiberoptic contact probes for energy delivery. Tissue responses were viewed with high-magnification videographic recording technique to analyze the real-time laser effects. The treated tissues were then studied by light microscopy. We observed different tissue responses both videographically and histologically. Nd:YAG laser lesions were characterized by prominent tissue whitening and contraction of the ciliary epithelium, while the diode laser lesions had less whitening and the tissue contraction appeared to be deeper in the ciliary body. The histologic correlate was coagulation and disruption of the ciliary epithelium and little effect on the underlying ciliary muscle with the Nd:YAG laser, while the diode laser had less effect on the ciliary epithelium but caused a significant coagulative response in the ciliary muscle. Comparative trials are needed to establish the clinical significance of these videographic and histologic observations.

Ciliary Body↗
PubMed1994

5-Fluorouracil after primary combined filtration surgery.

We examined the safety and efficacy of 5-fluorouracil in eyes with open-angle glaucoma undergoing combined cataract removal and filtration surgery. We randomly assigned one eye each of 24 patients to receive 5-fluorouracil (five injections of 5 mg during two weeks after surgery) and one eye each of 20 patients to comprise the control group. Preoperatively, the two groups had similar mean intraocular pressure (P = .8) and number of medications (P = .2). The mean intraocular pressure of the 5-fluorouracil group was 18.6 +/- 1.1 mm Hg, with 2.5 +/- 0.3 medications; that of the control group was 18.2 +/- 1.2 mm Hg, with 2.2 +/- 0.2 medications. One year postoperatively, intraocular pressure and the number of medications were significantly reduced by a similar amount in both groups of patients (5-fluorouracil, 14.2 +/- 0.7 mm Hg, 0.8 +/- 0.2 medications; controls, 14.3 +/- 0.6 mm Hg, 1.0 +/- 0.2 medications). Transient superficial punctate keratopathy occurred more frequently (P = .04) in the 5-fluorouracil group (16 of 24 eyes, 67%) than in the control group (seven of 20 eyes, 35%). In our randomized and prospective study, the adjunctive use of 5-fluorouracil did not result in improved control of intraocular pressure one year after combined surgery in eyes with open-angle glaucoma.

Aged↗
PubMed1994

Influence of exposure time on inflammatory response to neodymium:YAG cyclophotocoagulation in rabbits.

OBJECTIVE: To evaluate the influence of duration of exposure on the inflammatory response to transscleral neodymium:YAG cyclophotocoagulation. METHODS: Transscleral cyclophotocoagulation was performed with a contact, Nd:YAG, continuous-wave laser on one eye of 48 Dutch belted rabbits, 10 W and 0.2 second used in half and 1 W and 2 seconds in the other half. One third of each group was evaluated on the operative day and the other thirds on postoperative days 3 and 10. Tissue reaction was inspected grossly and by light microscopy, and inflammatory responses were measured by aqueous leukocyte and erythrocyte counts, aqueous and vitreous protein levels, aqueous prostaglandin levels, and iris and ciliary body myeloperoxidase activity. RESULTS: The shorter-duration protocol was associated with more ciliary epithelial disruption and significantly greater inflammatory responses by one or more of the measures at all times. CONCLUSION: When energy is constant, a shorter duration of exposure with transscleral Nd:YAG cyclophotocoagulation in rabbits is associated with greater tissue disruption and inflammation.

Animals↗