Search PubMed⌕ Search

Biomedical subjects

D C Musch

Publications and source records attributed to D C Musch.

At least 55 records · Page 3Linked to original sources
PubMed1991

The effect of glaucoma filtering surgery on corneal endothelial cell density.

Corneal endothelial cell counts were obtained preoperatively and 3 months postoperatively in 46 eyes undergoing glaucoma filtering surgery. Average central endothelial cell loss in eyes without postoperative iridocorneal touch was 1.6%. In eyes with iridocorneal touch (Spaeth's grades 1 and 2), the average cell counts decreased by 7.1% and 9.3%, respectively. The average loss for combined grades 1 and 2 (8.1%) approached statistical significance (P +/- .06). The average loss in two patients with corneolenticular touch (Spaeth's grade 3) was greater than 50%. These findings suggest that early postoperative iridocorneal touch is unlikely to lead to corneal compromise in most eyes, but that corneolenticular touch can result in severe endothelial cell loss.

Aged↗
PubMed1990

Facial nerve injury and hemifacial spasm.

We studied evidence of facial nerve damage in patients with hemifacial spasm. Three types of evidence of nerve damage were analyzed: objectively measured weakness in eyelid protractor strength, clinically evident weakness of muscles innervated by the seventh nerve, and clinically evident aberrant seventh nerve regeneration. Of the 60 patients in the study, 54 (90%) had at least one of these features of seventh nerve damage. Objectively measured eyelid protractor weakness was noted in 27 of 58 patients (47%) who were tested. Clinically apparent weakness of at least one of four facial muscle groups was noted in 42 of 60 patients (70%). Aberrant seventh nerve regeneration was documented in 25 of 60 patients (42%). These findings indicate that facial nerve damage is common in patients with hemifacial spasm.

Adult↗
PubMed1990

Time course of thymoxamine reversal of phenylephrine-induced mydriasis.

We conducted a randomized, double-masked, paired comparison of 0.1% thymoxamine vs placebo for the reversal of phenylephrine-induced mydriasis. Mydriasis was induced with 2.5% phenylephrine in each eye of 74 subjects (148 eyes). Each subject then received 0.1% thymoxamine in one eye and placebo in the other eye. Pupillary measurements were obtained at regular intervals during the ensuing 8 hours. At all intervals, a greater percentage of thymoxamine-treated eyes returned to baseline pupillary diameters compared with placebo-treated eyes (P less than or equal to .01). For subjects in whom both pupils returned to baseline, thymoxamine-treated eyes returned to baseline in a mean of 2.2 hours, vs 5.2 hours for placebo (P less than .0001). Among thymoxamine-treated eyes, those with light irides responded more rapidly than those with dark irides, returning to baseline in 1.6 vs 2.8 hours, respectively (P = .0046). After constriction to baseline pupillary diameter had been achieved, no patients experienced a rebound dilation.

Adolescent↗
PubMed1990

Effects of pupillary dilation on automated perimetry in normal patients.

The effects of pupillary dilation (tropicamide 1%) on automated static threshold perimetry were studied in 18 normal subjects using the Humphrey field analyzer 30-2 and STATPAC programs. The mean defect worsened by 0.83 decibels (standard deviation, 0.92 decibels) in dilated fields as compared with baseline visual fields (P = 0.001). These findings indicate that pupillary dilation in healthy subjects who are not receiving ocular medications produces statistically significant declines in threshold sensitivities. Valid comparison of results from serial visual field testing, therefore, depends on control of or adjustment for the effect of pupillary dilation.

Adult↗
PubMed1990

Endothelial rejection following penetrating keratoplasty using Healon or BSS.

In order to evaluate the effect of a commonly used sodium hyaluronate preparation (Healon, Pharmacia AB, Uppsala, Sweden) on the incidence of endothelial rejection, endothelial cell loss, intraocular pressure, and corneal thickness after penetrating keratoplasty, we conducted a randomized clinical trial. Patients were allocated to receive Healon (n = 41) or BSS (Alcon Laboratories, Inc., Fort Worth, TX, U.S.A.; n = 37) during surgery. At 1 year after surgery, the Kaplan-Meier estimate of the proportion remaining free of endothelial rejection was 78.1% (SE 6.5%) in the Healon group, and 70.6% (SE 7.9%) in the BSS group. Survival analysis showed no overall difference in endothelial rejection between groups. The percent loss in endothelial cell density showed substantial variability within each group, but for those followed 2 years after surgery, the amount of loss was significantly less in Healon-treated patients (17.3% versus 30.2%). Four Healon patients required medication for intraocular pressure rises in the early postoperative period, and the average intraocular pressure 1 day after surgery was greater in the Healon group (18.2 versus 13.7 mm Hg). Corneal thickness was slightly greater in patients receiving Healon, but no clinically important differences were noted.

Acetates↗
PubMed1989

A comparison of two methods of punctal occlusion.

We performed punctal occlusion by thermal cautery on 23 patients (45 sides, 90 puncta). One punctum on the right side was randomly assigned to deep cauterization of the punctum and vertical canaliculus, and the other punctum assigned to cauterization of the punctum only. The two treatments were assigned to the opposite puncta on the left side. One month after cauterization, the puncta that received deep cauterization were significantly more likely to have remained closed than those that received superficial cauterization (P less than .01). Survival analysis over a period of follow-up that exceeded one year after surgery, using time to examination because of a reopened punctum as the endpoint, indicated a long-term advantageous effect of deep over superficial cauterization.

Electrocoagulation↗
PubMed1989

Intraocular pressure effects of carbonic anhydrase inhibitors in primary open-angle glaucoma.

We tested the effect on intraocular pressure of three commonly used oral carbonic anhydrase inhibitor preparations in a controlled, randomized, comparative study on patients with primary open-angle glaucoma. Preparations tested included acetazolamide tablets, acetazolamide Sequels, and methazolamide tablets. The effect of the three carbonic anhydrase inhibitors was assessed by using a statistical modeling approach as well as by evaluating the average maximum reduction in intraocular pressure for each preparation. Dosage and time effects were also determined. As expected, each drug preparation was more effective in reducing intraocular pressure when administered to a patient who had already been treated with the carbonic anhydrase inhibitor preparation. The amount of intraocular pressure lowering was directly related to dose for both acetazolamide preparations. Of particular interest was the finding that maximal rapid reduction of intraocular pressure was obtained with a 500-mg dosage of acetazolamide tablets.

Acetazolamide↗
PubMed1989

Implantation of posterior chamber intraocular lenses in the absence of lens capsule during penetrating keratoplasty.

We retrospectively studied the clinical records and the corneal endothelial cell counts of 133 consecutive eyes that received sutured posterior chamber intraocular lenses during penetrating keratoplasty in the absence of lens capsular support. Postoperative follow-up time ranged from three to 24 months, with 82 patients having at least one year of follow-up. At one year, 45.1% of these patients had 20/40 or better visual acuity, 30.5% had a visual acuity between 20/50 and 20/100, and 24.4% had a visual acuity of 20/200 or worse. At two years, 63.6% had a visual acuity of 20/40 or better, 18.2% had a visual acuity between 20/50 and 20/100, and 18.2% had a visual acuity of 20/200 or worse. Ninety-seven percent of the grafts remained clear at their latest follow-up examination. Cystoid macular edema (36.4%) and age-related macular degeneration (14.0%) accounted for poor visual acuity in most cases. Less common problems included graft rejection, retinal detachment, glaucoma, and endophthalmitis. At one year, the endothelial cell loss in the grafts averaged 19% with sutured posterior chamber intraocular lenses.

Aged↗
PubMed1989

Effects of pupillary constriction on automated perimetry in normal eyes.

The authors studied the effects of pupillary constriction (pilocarpine 2%) on automated static threshold perimetry in 20 normal subjects using the Humphrey Field Analyzer 30-2 and STATPAC programs. The mean defect (MD) worsened by an average of 0.67 decibels (dB) (standard deviation, 0.67 dB) in constricted fields compared with baseline visual fields (P less than or equal to 0.001). Independent comparisons of the unweighted means of threshold values for the central 30 degrees, 24 degrees, and 10 degrees were also done and showed significant reductions in sensitivity after constriction (P less than or equal to 0.001). These findings indicate that changes in pupillary diameter may produce significant declines in threshold sensitivities and support the importance of consistent pupillary diameters on serial automated visual field examinations.

Adult↗
PubMed1989

Risk of endothelial rejection after bilateral penetrating keratoplasty.

Using univariate and multivariate survival analyses, the risk of endothelial rejection (ER) was compared between a group of patients undergoing penetrating keratoplasty (PK) in one eye only (unilateral PK) and a concurrent group who underwent PK in both eyes (bilateral PK). There was no significant difference in the time-related risk of ER between the bilateral and unilateral PK groups, after controlling for the increased risk of ER associated with younger age and preoperative stromal vascularity. Further analysis showed no increased ER risk to the first eye after the second eye's PK in the bilateral PK group. The documentation of simultaneous ER episodes in both eyes of two bilateral PK patients, however, may be evidence of an uncommon sharing of histocompatibility antigen(s) in the donor tissue used in these eyes.

Adolescent↗
PubMed1989

Corneal astigmatism after penetrating keratoplasty. The role of suture technique.

A randomized clinical trial was conducted to contrast two techniques of suturing in penetrating keratoplasty (PK) surgery: double running 10-0 and 11-0 sutures (DR), and a combination of 12 interrupted 10-0 sutures with a single running 11-0 suture (IR), followed by selective suture removal. The primary outcome evaluated in the 60 patients within each group was keratometric astigmatism. A decreasing trend in astigmatism over postoperative year 1 was observed only in the IR group (from 4.00 diopters [D] at 3 months to 2.50 D at 12 months). The difference in median astigmatism at 1 year (IR, 2.50 D; DR, 4.00 D) approached statistical significance (P = 0.06, Mann-Whitney U test). Both groups showed comparable steepening of almost 1 D during postoperative year 1. Assessment of the rate of visual rehabilitation was limited by a greater proportion of IR patients showing cystoid macular edema (CME) after surgery. These results, while favorable toward the IR/selective suture removal technique, must be substantiated by a final assessment after all sutures have been removed.

Aged↗
PubMed1989

Efficacy of the primary dye test.

A primary dye test was performed on the right lacrimal system of 25 normal subjects by three physicians of differing levels of experience in performing the test. The frequency of positive primary dye tests for each of the three examiners was higher than previously reported. The most experienced examiner had the highest percentage (100%) of positive primary dye tests, and the least experienced examiner had the lowest percentage (80%) of positive tests. However, variation between the most experienced examiner and the other two was due, at least in part, to a difference in fluorescein instillation. Therefore, the effect of experience could not be ascertained. The most experienced examiner used four moistened fluorescein strips medially and each used a 10-minute interval after dye instillation before looking for evidence of dye passage through the nasolacrimal duct. Twenty-one (84%) of the subjects had a positive primary dye test on initial blowing of the nose. This indicates that even inexperienced examiners can expect to detect a high percentage of functioning lacrimal drainage system with the method of the experienced examiner.

Adult↗
PubMed1989

A comparative study of eyelid parameters in involutional entropion.

A comparative study of eyelid parameters reported to be important in involutional entropion was made. Males and females aged greater than or equal to 65 years with normal eyelids, acute involutional entropion (history less than 6 weeks), and chronic involutional entropion (history greater than or equal to 6 weeks) were entered into the study. Significant findings were increased vertical laxity in each entropion group and increased horizontal laxity in the chronic entropion group. The upper eyelid action had an essential role in the turning in of affected lower eyelids. The degree of pretarsal overriding in the lower eyelid was not a significant differentiating feature when the groups were compared. The findings of this comparative study provide the basis for suggesting the pathophysiology of involutional entropion.

Aged↗
PubMed1989

Anterior chamber depth following filtration surgery.

We measured the anterior chamber depth in 20 consecutive phakic glaucoma patients undergoing thermal sclerostomy (n = 12) or trabeculectomy (n = 8). Using the Haag-Streit pachymeter, measurements were taken preoperatively and at postoperative days 1, 2, 3, 6, 15, and 42. In all eyes, shallowing of the anterior chamber was observed following surgery. It was greatest by postoperative day 2 or 3, with maximum mean decreases from preoperative anterior chamber depths of 70.9% for thermal sclerostomy and 54.0% for trabeculectomy. In 18 patients, the anterior chamber depth gradually deepened over the course of postoperative days 4 through 15, so that by 15 days after surgery, the average anterior chamber depth was 87.6% of the preoperative level. In two patients who ultimately required surgical reformation on their anterior chamber, however, only a minimal deepening occurred over this interval. At 15 days after surgery, the average anterior chamber of these two patients was significantly more shallow (37.5% of the preoperative anterior chamber depth, p = 0.003) than the mean of the other 18 patients (87.6% of the preoperative anterior chamber depth). These observations suggest that if the anterior chamber has not reformed by postoperative day 15, spontaneous reformation of the anterior chamber is unlikely and surgical intervention may be required.

Aged↗
PubMed1989

The effects of exercise on intraocular pressure in pigmentary glaucoma patients.

Previous studies of normal volunteers and open-angle glaucoma patients have shown that exercise temporarily lowers intraocular pressure. However, two case reports have described pigmentary dispersion syndrome patients who developed symptomatic increased intraocular pressure after exercise. We evaluated the intraocular pressure response to exercise in ten pigmentary glaucoma patients. An exercise protocol was designed to increase the likelihood of lens zonule-iris pigment epithelium contact. Intraocular pressure measurements during the first two hours after exercise showed no statistically significant elevation of mean intraocular pressure. The pressure rose 6 mm Hg and 7 mm Hg respectively at 15 minutes in two eyes, but returned to baseline by 30 minutes. Our results suggest that exercise may not significantly increase the clinical intraocular pressure in pigmentary glaucoma patients.

Adult↗
PubMed1988

The effect of omitting botulinum toxin from the lower eyelid in blepharospasm treatment.

We randomly selected 26 patients with essential blepharospasm to receive either botulinum toxin or saline injection in their lower eyelids to evaluate the necessity of lower eyelid injection to relieve blepharospasm. As diplopia may occur from botulinum toxin injections for blepharospasm, most commonly from injection of the lower eyelid, and surgical relief of blepharospasm is often achieved by excision of only the upper eyelid protractors, omission of toxin from the lower eyelid seemed both desirable and possible. All patients received botulinum toxin in the upper eyelids, above the eyebrows, across the glabella, and near the lateral canthus. Thirteen of 15 patients who received saline in their lower eyelids had relief of spasm, with the same spasm-free interval as those who received toxin. We recommend avoiding injection of toxin in the medial two thirds of the lower eyelid in order to diminish the likelihood of diplopia from inferior oblique muscle paresis.

Blepharitis↗
PubMed1988

A study of race matching between donor and recipient in corneal transplantation.

We investigated the influence of a racial match or mismatch between the corneal donor and recipient on the risk of endothelial rejection and subsequent graft failure in 998 corneal transplant recipients. Actuarial survival analysis showed no significant difference in the cumulative risk of endothelial rejection between the 676 race-matched and 322 race-mismatched recipients. Recipients who had preoperative factors that placed them at a higher risk of endothelial rejection (n = 208) also were not subject to a higher incidence of endothelial rejection if they received race-mismatched tissue. Graft failure after endothelial rejection was not found to differ among race-matched or -mismatched groups.

Black People↗