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Biomedical subjects

M B Shields

Publications and source records attributed to M B Shields.

At least 19 recordsLinked to original sources
PubMed2005

Trabeculectomy and optic nerve head topography.

The objective of the present study was to evaluate changes in optic nerve head parameters, measured by confocal laser tomography, before and after trabeculectomy in order to identify outcome measures for the management of glaucoma. The optic nerve head of 22 eyes (22 patients) was analyzed by confocal laser tomography with the Heidelberg retinal tomogram (HRT) before and after trabeculectomy. The median time between the first HRT and surgery was 4.6 months (mean: 7.7 +/- 8.3) and the median time between surgery and the second HRT was 10.8 months (mean: 12.0 +/- 6.8). The patients were divided into two groups, i.e., those with the highest (group A) and lowest (group B) intraocular pressure (IOP) change after surgery. Differences in the 12 standard topographic parameters before and after surgery for each group were evaluated by the Wilcoxon signed rank test and the differences in these parameters between the two groups were compared by the Mann-Whitney rank sum test. Multiple regression analysis was used to evaluate the influence of the change in IOP (DeltaIOP and DeltaIOP%) and the changes in the other parameters. There were significant differences in the HRT measures before and after surgery in group A only for cup volume. In group B, no parameter was statistically different. The changes in group A were not significantly different than those in group B for any parameter (P > 0.004, Bonferroni correction for multiple comparisons). DeltaIOP and DeltaIOP% had a statistically significant effect on Delta cup disk area, Delta cup volume and Delta mean cup depth. Changes in cup shape size were influenced significantly only by DeltaIOP. Some optic disc parameters measured by HRT presented a significant improvement after filtering surgery, depending on the amount of IOP reduction. Long-term studies are needed to determine the usefulness of these findings as outcome measures in the management of glaucoma.

Adult↗
PubMed2001

Influence of surgical reduction of intraocular pressure on regions of the visual field with different levels of sensitivity.

PURPOSE: To determine whether the ability to document improvement in visual fields after intraocular pressure (IOP) reduction can be enhanced by focusing on regions of the field with different levels of sensitivity. DESIGN: Cohort study. METHODS: This is a retrospective study. SETTING: Yale Eye Center. STUDY POPULATION: The visual fields (Octopus G2) of 30 eyes of 30 patients undergoing trabeculectomy. OBSERVATION PROCEDURE: Visual fields were evaluated a mean of three months before and 7.8 months after surgery. MAIN OUTCOME MEASURES: Change in sensitivity between the preoperative and postoperative visual fields (Delta S) was evaluated globally by comparing all 59 points of sensitivity and regionally in three groups according to preoperative sensitivity (pre-S): 25% of highest, 50% intermediate, and 25% of lowest points of sensitivity. Improvement in Delta S was also correlated with preoperative mean defect (pre-MD), percent intraocular pressure (IOP) reduction (Delta IOP%), and patient's age. RESULTS: Six visual fields showed improvement in Delta S when evaluated globally and nine showed improvement in pre-S subgroups. Of the latter, all nine showed improvement in the subgroup with the lowest pre-S, and two in the intermediate subgroup, but none in the subgroup with the highest pre-S. Combining the subgroups with the lowest pre-S and the highest Delta IOP% was associated with the highest mean Delta S. CONCLUSION: The ability to document improvement in visual fields following surgical reduction of IOP may be enhanced by focusing on subgroups of test points with lower baseline sensitivity.

Adult↗
PubMed2001

Latanoprost and cystoid macular edema in high-risk aphakic or pseudophakic eyes.

PURPOSE: To determine the magnitude of the association between latanoprost use and cystoid macular edema (CME) in high-risk aphakic or pseudophakic eyes. SETTING: Single referral glaucoma practice. METHODS: In a referral glaucoma practice, 40 consecutive patients with glaucoma uncontrolled on maximally tolerated medications without latanoprost were studied. Seven eyes were aphakic, and 33 eyes were pseudophakic. All eyes had an absent or open posterior capsule, and 29 eyes had 1 or more additional risk factors for developing CME. Latanoprost 0.005%, 1 drop at bedtime, was added to the patients' current regimen. Patients were instructed to check their vision in the treated eye daily at home and to report any perceived decrease promptly. Patients without a change in vision or other side effects were reexamined 1 month after initiating latanoprost and every 3 months thereafter. If there was a greater than 1 line decrease in visual acuity, a retinal evaluation and fundus fluorescein angiography (FFA) were performed by a retina specialist. RESULTS: Two eyes had to discontinue latanoprost because of side effects before the 1 month visit. They were excluded from the analysis. At the 1 month follow-up, the mean intraocular pressure was 18.2 mm Hg +/- 6.5 (SD), a decrease from the pretreatment mean of 21.5 +/- 5.7 mm Hg. The visual acuity was within 1 line of baseline in 36 eyes and decreased by 2 lines in 2 eyes. In these 2 eyes, symptomatic CME was documented by FFA. The CME clinically resolved, with visual acuity returning to baseline after the latanoprost was discontinued and a nonsteroidal antiinflammatory drug started. There were no additional cases of CME after a mean follow-up of 5.7 months. CONCLUSION: Approximately 5% of high-risk eyes treated with latanoprost developed clinically symptomatic and angiographically documented CME. The temporal relationship between initiation of treatment and the decreased vision in our 2 cases suggests but does not establish a causal relationship between CME and latanoprost. With appropriate informed consent and attentive follow-up, clinicians should not be deterred from using this important glaucoma medication.

Aged↗
PubMed2000

Long-term effect of Nd:YAG laser posterior capsulotomy on intraocular pressure.

OBJECTIVE: To study the long-term effect of Nd:YAG capsulotomy on intraocular pressure (IOP). METHODS: We reviewed the records of patients with bilateral pseudophakia who received Nd:YAG capsulotomy in only 1 eye. Using the Wilcoxon rank sum test, we compared the mean change in IOP in eyes before and after capsulotomy with that of the noncapsulotomy eyes at corresponding time intervals. Using multiple regression tests, we analyzed the factors significantly associated with postcapsulotomy long-term IOP increases. RESULTS: The study included 100 patients who were followed up for a median of 1.5 years after capsulotomy. The mean +/- SD age of the study group was 76+/-7 years, and 37 patients had glaucoma. The changes in IOP in the eyes treated with capsulotomy were significantly higher than those in noncapsulotomy eyes at each time interval following capsulotomy. The long-term IOP increase was significantly associated with the IOP increase measured 1 hour after the capsulotomy (P =. 001). Patients with glaucoma were more likely to require long-term additional glaucoma medication than were nonglaucoma patients to require initial glaucoma therapy after the capsulotomy (P =.002). CONCLUSION: After Nd:YAG capsulotomy, long-term IOP is often elevated above precapsulotomy baselines, especially in glaucoma patients or patients who experience a significant IOP increase within hours after the capsulotomy.

Aged↗
PubMed2000

A comparison of dorzolamide-timolol combination versus the concomitant drugs.

PURPOSE: To compare the intraocular pressure (IOP) lowering effect of fixed combination dorzolamide 2% and timolol 0.5% therapy to that of concomitant administration of a topical beta-blocker and dorzolamide. METHODS: Seventy-four consecutive glaucoma patients were changed from a regimen including a topical beta-blocker and dorzolamide to the fixed combination dorzolamide-timolol in 1 eye, with the other eye used as the control. The average IOP readings before and 1 month after the change were compared. RESULTS: The mean baseline IOP in the entire study population was 19.4 +/- 4.2 mm Hg in the study eyes and 16.9 +/- 4.2 mm Hg in the control eyes. Four weeks after the medication change, the mean IOP was 17.3 +/- 3.9 mm Hg in the study eyes (P <.001) and 16.1 +/- 4.1 mm Hg in the control eyes (P =.02). The difference between the mean IOP change of 2.1 mm Hg in the study eyes and 0.8 mm Hg in the control eyes was found to be statistically significant (P =.01). CONCLUSION: These findings suggest that the fixed combination dorzolamide-timolol therapy achieves additional lowering of the intraocular pressure compared with the concomitant administration of a beta-blocker and dorzolamide.

Adrenergic beta-Antagonists↗
PubMed2000

Effect of latanoprost as adjunctive therapy.

BACKGROUND: Latanoprost may be a useful adjunct in some patients receiving maximum tolerated medical therapy. We report our clinical experience with latanoprost when added to one or two other glaucoma medications. METHODS: Review of the charts of 53 patients with open-angle glaucoma whose intraocular pressure (IOP) was uncontrolled with one or two glaucoma medications and who had latanoprost added as a second or third drug. Patients whose IOP decreased by 3 mm Hg or more were considered to be responders. RESULTS: The shortest length of follow-up was 2.3 months (median 5.8 months). Latanoprost was given as a second medication to 35 patients, of whom 22 (63%) responded, with a mean IOP reduction of 6.1 mm Hg (standard deviation [SD] 2.73 mm Hg) (28.7% [SD 12.10%]). Of the 18 patients to whom latanoprost was given as a third medication, 10 (56%) responded, with a mean IOP reduction of 6.3 mm Hg (SD 3.86 mm Hg) (24.5% [SD 10.12%]). INTERPRETATION: Latanoprost provides additional IOP reduction in some patients with open-angle glaucoma when added to one or two other glaucoma medications.

Adrenergic beta-Antagonists↗
PubMed2000

Excisional bleb revision to correct overfiltration or leakage.

OBJECTIVES: To evaluate the effectiveness of excisional revision of filtering blebs for hypotony or leakage when more conservative measures have failed. PATIENTS AND METHODS: Retrospective review of all patients who underwent excisional revision of a filtering bleb for hypotony (intraocular pressure [IOP] < 5 mm Hg) or leakage during a 3 year period. The revision consisted of excision of the avascular bleb, mobilization of the surrounding conjunctiva, and suturing of the conjunctiva at the limbus. RESULTS: Sixteen patients were included in the study. The average age was 66.3 +/- 14.8 years (range, 39-83). Revision followed trabeculectomy in 11 cases, combined phacoemulsification-trabeculectomy in three cases, and inadvertent blebs in two cases. Five cases had bleb leaks without hypotony, four cases had hypotony alone, and seven cases had both hypotony and a bleb leak. Average follow-up after bleb revision was 25 +/- 11 months (range, 9-43). Average IOP increased from 3.8 +/- 5.6 mm Hg (range, 0-22) to 11.9 +/- 4.1 mm Hg (range, 3-18), with an average of 1.1 +/- 1.1 medication (range, 0-3). The IOP at the last visit was < 15 mm Hg in all but two patients, with 10 of the 16 patients requiring medications. At the last follow-up examination, visual acuity had improved > or = two lines in nine patients and was reduced two lines in one patient. Five patients had early postoperative limbal wound leaks; resuturing was required in one case. CONCLUSIONS: Excisional bleb revision is an effective technique to correct hypotony or leakage after filtering surgery when other methods have failed. Intraocular pressure control is often maintained with the use of medications.

Adult↗
PubMed2000

Influence of keratometric readings on comparative intraocular pressure measurements with Goldmann, Tono-Pen, and noncontact tonometers.

PURPOSE: To evaluate the influence of keratometric measurements on the concordance of intraocular pressure (IOP) readings with three applanation tonometers. PATIENTS AND METHODS: The IOPs of 404 eyes of 202 patients from a general eye clinic were measured by Goldmann, Tono-Pen XL, and noncontact Nidek NT 2000 tonometers. Differences in the IOP measurements between Goldmann and the other two tonometers (deltaIOPG-TP and deltaIOPG-NCT) were analyzed in the overall group and within three subgroups based on keratometry measures: flatter, intermediate, and steeper corneas (quartiles as cut-off points). Regression analysis of deltaIOP and keratometry measures was also performed. Right and left eyes were analyzed separately. RESULTS: The IOP readings taken with the Goldmann tonometer were significantly higher than those taken with either of the other two tonometers within the overall study population. The deltaIOP within the three keratometric subgroups was not statistically significant except for deltaIOPG-TP in the right eyes. Regression analysis showed that keratometry and deltaIOPG-TP and deltaIOPG-NCT had a significant but very weak coefficient of correlation in the right eye, but not in the left. CONCLUSION: Corneal curvature within the normal range does not have a clinically significant influence on the concordance of IOP readings obtained with Goldmann and Tono-Pen or noncontact tonometers.

Adolescent↗
PubMed2000

Visually significant cystoid macular edema in pseudophakic and aphakic patients with glaucoma receiving latanoprost.

PURPOSE: To investigate the incidence of visually significant cystoid macular edema associated with the use of latanoprost in patients with glaucoma after cataract surgery. PATIENTS AND METHODS: This is a multicenter, retrospective study of 185 patients, of whom 173 were pseudophakic (212 eyes) and 12 were aphakic (13 eyes), who were treated for glaucoma with latanoprost 0.005%. The posterior lens capsule was intact in 125 eyes, open or absent as a result of surgery in 25 eyes, and status-post-yttrium-aluminum-garnet capsulotomy in 75 eyes. Visual acuity was documented before and after initiating latanoprost therapy, and patients with a reduction of two or more lines on the Snellen chart were examined by fluorescein angiography for cystoid macular edema. RESULTS: Visual reduction was documented in four (2.16%) patients. Three of the four patients had cystoid macular edema, and the fourth was thought to have lost a central island of vision from glaucoma. The three patients with cystoid macular edema all had ruptured posterior capsules, requiring anterior vitrectomy, and one had a previous episode of cystoid macular edema 3 years before starting latanoprost therapy. CONCLUSION: These findings suggest that visually significant cystoid macular edema associated with latanoprost therapy in pseudophakic or aphakic patients is uncommon. If there is a cause-and-effect relationship between latanoprost therapy and clinically significant cystoid macular edema, the incidence appears to be low.

Adolescent↗
PubMed1998

Laser energy reaching the posterior pole during transscleral cyclophotocoagulation.

OBJECTIVE: To measure scattered laser energy reaching the posterior pole during transscleral cyclophotocoagulation. METHODS: Transscleral cyclophotocoagulation was performed on 4 cadaver eyes with Nd:YAG noncontact, Nd:YAG contact, and diode contact lasers. Energy was measured with a photodiode through a 7-mm trephined hole in the posterior pole. Average percentage power, average power, and average energy transmission were calculated. American Conference of Governmental Industrial Hygienists (ACGIH) guidelines were used to calculate allowable energy exposures for each laser. RESULTS: All 3 lasers transmitted 3% to 5% of the power to the posterior pole. The average energy transmission was 240 to 260 mJ for all lasers. The contact lasers had an average power transmission of 120 mW. The noncontact Nd:YAG laser, with shorter pulse duration, had an average power transmission of 13,000 mW, significantly greater than that of the other lasers. The ACGIH guidelines for allowable energy exposures were 93 mJ for the noncontact Nd:YAG laser, 1300 mJ for the contact Nd:YAG laser, and 440 mJ for the contact diode laser. CONCLUSIONS: Three percent to 5% of laser power delivered during cyclophotocoagulation reaches the posterior pole. Exposure energies may approach or exceed ACGIH guidelines. The clinical significance of these findings remains to be shown.

Aged↗
PubMed1998

A clinical comparison of transscleral cyclophotocoagulation with neodymium: YAG and semiconductor diode lasers.

PURPOSE: To compare the efficacy of transscleral cyclophotocoagulation using a neodymium: YAG (Nd:YAG) or semiconductor diode laser in controlling intraocular pressure in patients with refractory glaucoma. METHODS: In a prospective study, 95 eyes of 91 patients with refractory glaucoma randomly received Nd:YAG or diode cyclophotocoagulation. Patients were followed for a mean of 10.4 months (10.42 +/- 3.16, mean +/- SD). We compared available data preoperatively and at 1 week, 1 month, 6 months, and 12 months postoperatively. Data analyzed were corrected visual acuity, intraocular pressure, and the type of glaucoma. RESULTS: There was a statistically significant decrease in intraocular pressure after both Nd:YAG and diode cyclophotocoagulation at each time period. However, there were no significant differences in postoperative intraocular pressure or visual acuity change between Nd:YAG and diode procedures. CONCLUSIONS: Compared with the Nd:YAG laser for transscleral cyclophotocoagulation, the diode laser has technological advantages including portability, durability, and smaller size, while providing equivalent postoperative intraocular pressure and visual acuity change.

Adult↗
PubMed1998

Results of trabeculectomy with 0.3 mg/ml mitomycin C titrating exposure times based on risk factors for failure.

PURPOSE: To examine the efficacy of trabeculectomy with mitomycin C 0.3 mg/ml using titrated exposure times. METHODS: A retrospective chart review of consecutive patients undergoing trabeculectomy in an academic referral glaucoma clinic was performed. All patients received trabeculectomies performed by one surgeon (M.B.S.). The study included 57 eyes of 57 patients using mitomycin C with exposure times titrated from one to five minutes based on risk factors for trabeculectomy failure. Surgical success was defined as a final intraocular pressure (IOP) of less than 21 mmHg with or without medications or a 25% reduction in IOP if preoperative IOP was 21 mmHg or less. Patients requiring repeat trabeculectomies were considered failures regardless of their final IOP. Patients receiving different mitomycin C exposure times were compared but statistical analysis was not used because these subgroups were not randomized. RESULTS: An overall surgical success rate of 84.2% was achieved at a mean follow-up of 11.9 months. The surgical success rate and percentage IOP reduction was similar between exposure time subgroups. Hypotonous maculopathy observed in three patients (5.3%). All cases of hypotonous maculopathy was occurred in the lower-risk patients receiving one to three minute exposure times to mitomycin C. CONCLUSIONS: We believe mitomycin C should be used sparingly if at all in patients at lower risk for trabeculectomy failure. This concentration of mitomycin C with four to five minute exposure times appears to be efficacious for patients with multiple risk factors for trabeculectomy failure.

Administration, Topical↗
PubMed1997

Central corneal thickness in normal, glaucomatous, and ocular hypertensive eyes.

OBJECTIVE: To determine the relationship between central corneal thickness (CCT) and applanation intraocular pressure (IOP) in normal, glaucomatous, and ocular hypertensive eyes. METHODS: One hundred nine subjects (184 eyes) were studied. Forty-eight patients (74 eyes) had glaucoma, 28 patients (51 eyes) had ocular hypertension, and 33 patients (59 eyes) were normal. Intraocular pressure as measured by applanation tonometry, refractive status, CCT, and axial length were measured for all subjects. RESULTS: The CCT (mean +/- SD) of eyes with ocular hypertension was significantly greater (0.606 +/- 0.041 mm) than that of glaucomatous eyes (0.554 +/- 0.022 mm) (P < .001) or of normal controls (0.561 +/- 0.026 mm) (P < .001). There was no significant difference in CCT between normal and glaucomatous eyes (P = .40). The axial length (mean +/- SD) of eyes with ocular hypertension (23.54 +/- 1.34 mm) was not different compared with glaucomatous eyes (23.93 +/- 0.96 mm) (P = .13) or normal eyes (23.62 +/- 1.21 mm) (P = .83). There was no significant difference between the axial length for glaucomatous eyes compared with normal eyes (P = .18). Those eyes with glaucoma being treated with topical dorzolamide hydrochloride had a significantly increased CCT (0.560 +/- 0.025 mm) compared with those eyes with glaucoma not being treated with dorzolamide (0.551 +/- 0.20 mm) (P = .02). CONCLUSIONS: The mean CCT is increased in eyes with ocular hypertension when compared with normal or glaucomatous eyes, which confirms the findings of other investigators. Increased CCT may give an artificially high IOP measurement by applanation tonometry. The CCT must be considered when developing a treatment approach for patients with ocular hypertension.

Aged↗