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Biomedical subjects

D C Musch

Publications and source records attributed to D C Musch.

At least 73 records · Page 4Linked to original sources
PubMed1988

The effect of removing running sutures on astigmatism after penetrating keratoplasty.

To evaluate astigmatic change after removal of the double running sutures used in penetrating keratoplasty, all patients (N = 131) in the Michigan Corneal Transplantation Patient Registry, Ann Arbor, whose eyes were phakic after penetrating keratoplasty were evaluated. The primary reasons for surgery in this group were keratoconus (n = 44, 34%) and Fuchs' corneal dystrophy (n = 19, 15%). The average effect of 10-0 suture removal in 58 eyes with documented keratometry readings was a 0.30-diopter (D) decrease in astigmatism, with 59% showing 2 D or less of astigmatic change. In 83 eyes with keratometry readings before and after 11-0 suture removal, an average increase of 0.37 D of astigmatism was observed, with 81% showing less than 2 D of astigmatic change. In eyes that were highly astigmatic (greater than 6 D) before suture removal, a reduction in astigmatism exceeding 2 D was observed in 39% and 11% after 10-0 and 11-0 suture removal, respectively.

Astigmatism↗
PubMed1988

Significance of cilioretinal arteries in primary open angle glaucoma.

Greater optic nerve and visual field damage has been reported in eyes with primary open angle glaucoma that also have cilioretinal arteries compared with fellow eyes that do not have cilioretinal arteries. The cilioretinal artery may shunt blood from the posterior ciliary arterial circulation away from the optic nerve, especially in the inferior and superior optic disc, where early glaucomatous damage often occurs. To evaluate these observations, we reviewed stereoscopic disc photographs of 122 patients with primary open angle glaucoma. Twenty-one patients had unilateral cilioretinal arteries and bilateral primary open angle glaucoma with an intraocular pressure greater than 21 mm Hg at presentation and a difference of 3 mm Hg or less between the eyes. Stereoscopic disc photographs and Goldmann visual fields were evaluated in a masked fashion. In glaucomatous eyes with comparable intraocular pressures, we found no significant optic nerve or visual field differences in eyes with cilioretinal arteries compared with eyes without cilioretinal arteries.

Adult↗
PubMed1988

Prospective evaluation of a regression-determined formula for use in triple procedure surgery.

A surgeon-specific regression equation was applied prospectively to determine the intraocular lens (IOL) power for use in 52 consecutive patients undergoing triple procedure surgery. At their final refraction, 85% (44/52) of these patients could see 20/40 or better. Upon comparing the preoperatively determined refractive goal with that actually obtained, an "ideal" IOL power which would have resulted in the refractive goal was determined. The IOL power selected by the regression formula was within 2 diopters (D) of the ideal IOL power in 67% (35/52) of the cases. For comparison, the power which would have been selected if the Sanders-Retzlaff-Kraff (SRK) or Binkhorst formula was used would have been within 2 D of the ideal IOL power in 62% (SRK, 32/52) and 58% (Binkhorst, 30/52) of the cases. Deviations from the ideal IOL power were predominantly in the undercorrected category for all three formulas evaluated. The authors conclude that even though a surgeon-specific regression formula relying on preoperative axial length performed fully as well as either the SRK or Binkhorst formulas, the choice of which formula to apply remains in the surgeon's hands.

Cataract Extraction↗
PubMed1987

Assessment of success and complications of triple procedure surgery.

In an effort to quantify both the success and complications of triple procedure surgery, we studied a consecutive series of 166 patients who underwent this procedure. The average length of follow-up was 17 months. Of 166 patients, 138 (83%) achieved a visual acuity of 20/40 or better after surgery; in the most recent 52 patients, 26 (50%) achieved this within two months. The most frequent complications during the postoperative period were glaucoma (40 patients, 24%), endothelial graft rejection episodes (two-year cumulative risk, 16%), and astigmatism (mean keratometric cylinder, 4.97 D). Additional surgical interventions were required in 27 patients (16%).

Aged↗
PubMed1987

Clinical comparison of the Oculab Tono-Pen to the Goldmann applanation tonometer.

The Oculab Tono-Pen tonometer was compared with the Goldmann applanation tonometer through studies on 197 eyes of 103 patients with glaucoma or ocular hypertension to evaluate the reliability of the Tono-Pen in determining intraocular pressure (IOP). Patients were randomized into four groups and all applanations were done by the same investigator. The Tono-Pen initially used (Tono-Pen #1) failed to calibrate after being used on 77 eyes. Tono-Pen #2 was then obtained and tested. Each Tono-Pen showed high correlation with the Goldmann readings (r greater than or equal to 0.86 in both eyes). The overall sensitivity of the Tono-Pen in detecting IOPs of 21 mmHg or higher (as measured by the Goldmann instrument) was 62.1% in right eyes, 72.4% in left eyes, with corresponding specificities of 92.6% in the right and 97.1% in the left. Given the substantial increase in sensitivity noted with Tono-Pen #2, the Tono-Pen appears adequate for screening programs where an IOP of 21 mmHg or above is considered abnormal; however, at higher IOPs (greater than or equal to 30 mmHg) the Tono-Pens tended to underestimate Goldmann IOPs. At low IOPs (less than or equal to 9 mmHg) the Tono-Pens tended to overestimate the IOPs. Perhaps with further modifications of the instrument, it could be used for clinical diagnosis and management of glaucoma patients.

Analysis of Variance↗
PubMed1986

Retinal detachment following penetrating keratoplasty.

The time-related risk of retinal detachment during the follow-up of 1146 penetrating keratoplasty procedures was evaluated, using survival analysis techniques. Twenty-eight retinal detachments were observed during follow-up. The Kaplan-Meier estimate of the risk of developing retinal detachment increased from 1.5% at three months to 2.1% at one year after surgery. Further follow-up showed a gradual increase in the cumulative proportion developing retinal detachment to 4.7% at 3.5 years after surgery. Of the preoperative and intraoperative factors available for study, performing an anterior vitrectomy during penetrating keratoplasty was associated with a greater risk of postoperative retinal detachment. The outcome of visual acuity following retinal detachment in these patients' eyes was poor; five patients could not perceive light with the affected eye, and 82% (23/28) had visual acuity of 20/200 or less.

Corneal Transplantation↗
PubMed1986

Treatment of facial spasm with botulinum toxin. An interim report.

Forty-eight patients were given serial injections of botulinum toxin in their eyelids for treatment of eyelid spasm during a two-year interval. Ninety-four percent obtained relief of spasm from botulinum toxin injection. The duration of the spasm-free interval as well as the incidence of ptosis and of diplopia was dose dependent. The marked increase in the incidence of these side effects with only a small increase in the duration of the spasm-free interval, when a dose of 25 units per lid was used, leads the authors to conclude that this dose is too high and should not be used. Since diplopia was most commonly caused by paresis of the inferior oblique muscle, and since blepharospasm usually can be controlled by excising the upper lid protractors, further studies are required to determine whether lower lid injection is necessary and, if it is found to be so, whether injecting only the lateral portion of the lid would be adequate.

Blepharospasm↗
PubMed1986

Lid protractor force generation in Graves' eye disease.

The posterior vector of the lid protractor force was measured in 29 patients with Graves' eye disease (GED) and 70 normal subjects. Patients with GED had significantly lower mean lid protractor force generation than normal subjects, although GED patients with compressive optic neuropathy did not show this difference. There was a negative correlation between the posterior force vectors and the exophthalmometer reading in GED patients only. It is conjectured that these two factors are linked by orbital and lid inflammation. The inflammation that increases orbital bulk, and thus increases the exophthalmometer reading, may well cause atrophy in the orbicularis oculi muscles, decreasing its force generation.

Exophthalmos↗
PubMed1986

Effect of 1% sodium hyaluronate (Healon) on a nonregenerating (feline) corneal endothelium.

A series of experiments were performed to investigate the effect of 1% sodium hyaluronate (Healon) on the nonregenerating corneal endothelium of the cat. Aqueous humor replacement with 1% sodium hyaluronate resulted in mild, transient elevations of intraocular pressure compared to eyes that were injected with balanced salt solution. Sodium hyaluronate 1% protected the feline endothelium against cell loss incurred by contact with hyaluronate-coated intraocular lenses compared to endothelial contact with lenses that were not coated with sodium hyaluronate. The use of intraoperative 1% sodium hyaluronate, however, did not protect against endothelial cell loss incurred by penetrating keratoplasty or prevent subsequent skin graft-induced corneal homograft rejections. Homograft rejections were milder, however, in some eyes that received grafts coated with 1% sodium hyaluronate. Image analysis of photographs of trypan blue- and alizarin red-stained corneal buttons after trephining, stretching of Descemet's membrane, rubbing against iris-lens preparations, or immediately after penetrating keratoplasty demonstrated that the stretching of the posterior cornea is an important cause of endothelial damage that would not be protected against by a viscoelastic coating.

Animals↗
PubMed1986

Exophthalmometer readings in patients with Graves' eye disease.

Exophthalmometer readings were measured in 84 patients with Graves' eye disease (GED) and 111 normal subjects. The mean exophthalmometer reading was significantly greater in patients with GED than in normal subjects. Asymmetry of the orbital disease produced less correlation of the exophthalmometer readings between right and left eyes of GED patients than is found in normal subjects. Expected gender and age effects on the exophthalmometer reading were not found among the GED patients. The mean exophthalmometer reading was not significantly higher for GED patients with compressive optic neuropathy than in the other subgroups of GED patients, suggesting that exophthalmos per se is not harmful to the optic nerve.

Adolescent↗
PubMed1986

The effects of Graves' eye disease on levator muscle function.

The levator function and exophthalmometer reading were measured on each side of 81 patients with Graves' eye disease (GED) and 111 normal subjects. There was a significant positive correlation between the levator function and exophthalmometer reading for both GED patients and normal subjects. This indicates that the forward position of the eye chronically stretches the levator muscle by the addition of sarcomeres which increases the range of movement of the lid. The range of movement may be decreased in patients with Graves' eye disease, from inflammation, such as is seen with other extraocular muscles. This effect is most likely to be marked in the patient with compressive optic neuropathy.

Adult↗
PubMed1986

Lid retraction and levator aponeurosis defects in Graves' eye disease.

Vertical palpebral fissure determinants and lid crease height were measured in patients with Graves' eye disease (GED) and in normal subjects. The fissure and crease height are positively correlated with exophthalmometer readings in each group. Compensatory levator aponeurosis defects are shown to occur in patients with GED. These, along with the effect of exophthalmos on the lower lid position, the observation that the lower lid is closer to the inferior limbus than the upper lid is to the superior limbus in normal subjects, and the effect of contracture of the inferior rectus on the lower lid position, explain why inferior scleral show is found to be greater than superior scleral show in patients with GED. Thus, lid retractor surgery in GED patients should be performed only after the palpebral fissure, levator function, and lid crease height stabilize, and after any contemplated surgery that would alter the exophthalmos and extraocular muscles has been performed.

Adolescent↗
PubMed1985

Positional effects on exophthalmometer readings in Graves' eye disease.

Forty-eight patients with Graves' eye disease, half of whom had extraocular muscle restriction, and 45 normal adult subjects underwent exophthalmometry while in the upright and the supine positions to determine whether the difference in measurement due to position would serve to differentiate the groups. A previous report claimed that the upright reading would be greater than the supine reading for normal subjects and patients with Graves' eye disease without clinical extraocular muscle involvement, whereas those with extraocular muscle restriction would show little change in their exophthalmometer readings. Our study showed an increase in exophthalmometer readings in going from the upright to the supine position for normal subjects and both groups of patients with Graves' eye disease. Furthermore, this test did not serve to differentiate these three groups.

Adolescent↗
PubMed1985

Oversized donor grafts in penetrating keratoplasty. A randomized trial.

One hundred seventy-three aphakic or phakic corneal transplants were analyzed in a prospective randomized study to determine the effect of oversized corneal donor buttons on intraocular pressure, corneal curvature and astigmatism, wound dehiscence, and anterior chamber depth. We compared 93 oversized grafts with 80 same-sized grafts. In aphakic eyes, oversized grafts showed a trend toward lower incidence of elevated intraocular pressure during the early post-operative period and lower prevalence of glaucoma at the final visit, although this was not statistically significant. No such trends were seen in phakic eyes. Postoperative corneal curvature was significantly steeper in oversized than same-sized grafts, in both phakic and aphakic eyes; there was no difference in postoperative astigmatism. Anterior chamber depth was significantly greater in oversized grafts. Of four wound dehiscences, all occurred in same-sized grafts.

Aphakia↗
PubMed1985

The reliability of Hertel exophthalmometry. Observer variation between physician and lay readers.

In order to quantify and characterize the interobserver variation in exophthalmometry and to assess the impact of experience on that variation, four observers of varying levels of experience obtained an exophthalmometer reading from 100 subjects' right eyes and 97 subjects' left eyes. Observers were masked to the measurements of their colleagues. The subjects measured were referrals to the eye plastic and orbital service over a three week interval. Substantial interobserver variation was demonstrated. Fully one-fourth to one-third of all measurements by the three less-experienced observers differed enough from the senior observer to be of concern to him. The direction of disagreement varied with experience. The least-experienced observer consistently underread whereas the more experienced observer slightly overread exophthalmometry, relative to the senior observer. As the study progressed, the least-experienced observer's reliability increased. Interobserver agreement for this observer was influenced by the degree of proptosis presenting in the eye being measured.

Analysis of Variance↗
PubMed1985

Is there a racial difference in physiologic cup size?

Although many clinicians believe that there is a racial difference in the size of the physiologic cup, this premise has not been studied. To evaluate this, we prospectively examined 100 black and 100 white volunteers. Stereoscopic optic disc photographs taken of each subject were masked to block out the fundus pigmentation, randomized, and then evaluated by an experienced clinician. The average cup/disc ratio in blacks (0.35) was significantly greater (P less than 0.0001) than that in whites (0.24) for both right and left eyes. Forty percent of the optic discs of blacks and 14% of the optic discs of whites had a cup/disc ratio greater than or equal to 0.4.

Adult↗