Tail states in a superconductor with magnetic impurities

A field theoretic approach is developed to investigate the profile and spectrum of subgap states in a superconductor subject to a weak magnetic impurity potential. Such states are found to be associated with spatially inhomogeneous instanton configurations of the action.

Posterior fixation suture augmentation of full-tendon vertical rectus muscle transposition for abducens palsy

OBJECTIVE

To evaluate the effect of augmenting full-tendon vertical rectus transpositions with posterior fixation sutures in patients with complete or near-complete lateral rectus palsy.

METHODS

Transposition of the vertical recti to the lateral rectus muscle was performed in seven patients with unilateral lateral rectus palsy (the mean angle of preoperative horizontal deviation in primary gaze was 36.7 prism diopters (delta); range, 25-62delta of esotropia). A posterior fixation suture of 5.0 Mersilene (Ethicon, Somerville, NJ) was placed in sclera (14-16 mm posterior to the limbus) adjacent to the lateral rectus and incorporated 1/3 belly width of each transposed vertical rectus muscle.

RESULTS

The mean angle of postoperative horizontal deviation in primary gaze was 7.1delta (range, 0-20delta). The mean change in primary-position horizontal deviation postoperatively was 41.2delta (range, 37-72delta). Four patients were able to fuse without prism in primary gaze; three patients were orthophoric and one patient had a consecutive intermittent exotropia. The remaining three patients required prism correction to neutralize the postoperative gaze deviation. All patients had improvement in abduction. Mild limitation of adduction was noted in three patients (range, -0.5 to -2.0).

CONCLUSIONS

Augmenting full vertical rectus muscle transpositions with posterior fixation sutures improves the abducting effect of surgery without significant limitation of adduction.

Pediatric photoscreening for strabismus and refractive errors in a high-risk population

OBJECTIVE

To determine the accuracy of the MTI Photoscreener in detecting strabismus and refractive errors in children.

PARTICIPANTS

One hundred children underwent MTI photoscreening followed by complete ophthalmologic examination. Six observers graded the photographs for strabismus, according to the location of the corneal light reflexes, and for refractive error, according to the size and location of the light crescent.

RESULTS

The sensitivity of the MTI Photoscreener in detecting any amblyogenic factor was 80% to 91%, with a specificity of 20% to 67%. The sensitivity and specificity for particular amblyogenic factors varied widely among observers. The ranges were as follows: strabismus, sensitivity = 23% to 50%, specificity = 76% to 96%; myopia, sensitivity = 89%, specificity = 48% to 76%; hyperopia, sensitivity = 20% to 80%, specificity = 88% to 96%; and astigmatism, sensitivity = 46% to 77%, specificity = 79% to 89%.

CONCLUSIONS

These results suggest caution in relying on photoscreening to detect strabismus and refractive errors in children.

Surgical management of ocular motor cranial nerve palsies

This article reviews the various surgical treatment approaches currently used in the management of ocular motor cranial nerve palsies. Regardless of the approach, the final goal is improved alignment, especially in the primary and reading positions.

Surgical technique, visual outcome, and complications of pediatric intraocular lens implantation

PURPOSE

To evaluate retrospectively the surgical technique, visual outcome, and complications of pediatric cataract extraction (CE) and intraocular lens (IOL) implantation.

METHODS

Forty-three patients ages 2 to 12 underwent CE with IOL implantation with a minimum follow up of 1 month.

RESULTS

All IOLs were implanted in the posterior chamber with 17 (40%) in the bag, 25 (58%) sulcus fixated, and one (2%) partially in the bag (one haptic in the bag, one in the sulcus). Primary posterior capsulectomy was performed in 12 (28%) cases. A final visual acuity of at least 20/40 was achieved in 26 (60%) and at least 20/80 in 32 (74%). Posterior capsule opacification developed in 18 (42%) and pupillary capture in 7 (16%). Seventeen (40%) patients had postoperative visual acuity worse than 20/40. Of these, nine (53%) had this visual outcome as a result of presumed amblyopia.

CONCLUSIONS

Posterior chamber IOL implantation affords a safe and effective method of visual rehabilitation for cataractous children 2 years of age and older. Amblyopia and antecedent posterior segment trauma, rather than IOL-related or surgical complications, are the limiting factors in final visual outcome.

Calculation of relaxation rates from microscopic equations of motion

For classical systems with anharmonic forces, Newton's equations for particle trajectories are nonlinear, while Liouville's equation for the evolution of functions of position and momentum is linear and is solved by constructing a basis of functions in which the Liouvillian is a tridiagonal matrix, which is then diagonalized. For systems that are chaotic in the sense that neighboring trajectories diverge exponentially, the initial conditions determine the solution to Liouville's equation for short times; but for long times, the solutions decay exponentially at rates independent of the initial conditions. These are the relaxation rates of irreversible processes, and they arise in these calculations as the imaginary parts of the frequencies where there are singularities in the analytic continuations of solutions to Liouville's equation. These rates are calculated for two examples: the inverted oscillator, which can be solved both analytically and numerically, and a charged particle in a periodic magnetic field, which can only be solved numerically. In these systems, dissipation arises from traveling-wave solutions to Liouville's equation that couple low and high wave-number modes allowing energy to flow from disturbances that are coherent over large scales to disturbances on ever smaller scales finally becoming incoherent over microscopic scales. These results suggest that dissipation in large scale motion of the system is a consequence of chaos in the small scale motion.

Outcome of surgical management of superior oblique palsy: a study of 123 cases

PURPOSE

To determine the outcome of the surgical management of superior oblique palsy at our institution.

SUBJECTS AND METHODS

Retrospective review of 123 patients who underwent surgical correction of superior oblique paresis at Bascom Palmer Eye Institute from 1976 to 1996. Subject-Patients: 67% were male and 33% female. The mean age at surgery was 30.5 years (range, 2-78 years). Etiologies of the pareses were trauma (34%), congenital (33%), and acquired/non-traumatic (33%). The mean angle of preoperative vertical deviation in primary gaze was 14.0 delta (range, 0-45 delta).

SURGERY

109/123 (89%) patients underwent single muscle surgery. Of these 109, 57 had single oblique muscle surgery: a superior oblique tuck in 34/57 (60%); an inferior oblique weakening procedure in 22/57 (38%); and a Harada-Ito procedure in 1/57 (2%). The other 14 patients (11%) had bilateral surgery.

RESULTS

The final postoperative vertical deviation in primary gaze was < or =3 PD in 60% of patients and < or =7 PD in 80%. The mean change in primary position vertical deviation postoperatively was 10.4 PD for distance and 13.0 PD for near. An "excellent" outcome (final vertical deviation &le3 PD in primary and reading gazes) was achieved most frequently in those patients with congenital pareses and isolated oblique muscle surgery.

COMPLICATIONS

Clinically significant Brown's Syndrome occurred in 43/72 (60%) of those cases who had undergone a superior oblique tuck. The incidence of Brown's Syndrome was unrelated to tuck size. Reoperation was three times more likely to be necessary in traumatic cases than in congenital cases (35.0% vs 11.9%, p=0.02).

CONCLUSIONS

Based on these results we recommend oblique muscle surgery as the initial procedure to correct superior oblique palsy when appropriate.

A pars plana approach for cataract surgery in posterior lenticonus

PURPOSE

To report the management and outcome of cataract surgery and intraocular lens placement in a child with unilateral posterior lenticonus.

METHODS

Case report. A 7-year-old boy with a best-corrected visual acuity of RE, 20/200, posterior lenticonus, and cataract underwent a pars plana lensectomy, vitrectomy, posterior chamber intraocular lens insertion into the ciliary sulcus, and central anterior capsulotomy.

RESULT

At 2 years of follow-up, best-corrected visual acuity was RE, 20/40.

CONCLUSION

This technique allowed complete removal of the opaque posterior lenticonus plaque while preserving the peripheral anterior capsule for sulcus fixation of the posterior chamber intraocular lens.

Branch retinal vein occlusion. Axial length and other risk factors

OBJECTIVE

To determine the association between axial length, as a measurement of hyperopia, and branch retinal vein occlusion and to determine the clinical characteristics and other risk factors of patients with branch retinal vein occlusion.

METHODS

A case-control study was performed using 36 patients with branch retinal vein occlusion and 36 age- and sex-matched control patients selected from a list of subjects who had undergone cataract extraction.

RESULTS

There was essentially no difference in axial length between patients the disorder and control patients (23.55 mm versus 23.62 mm; P = 0.79). Although the intraocular pressure (IOP) among control eyes was somewhat higher than that in branch retinal vein occlusion eyes, the difference was not statistically significant (P = 0.32). Systemic hypertension was more common in patients with branch retinal vein occlusion (53%) than in control patients (42%) but the difference was not statistically significant (P = 0.35). Chronic open-angle glaucoma was present in 14% of patients with branch retinal vein occlusion and 22% of control patients (P = 0.37), but this difference was not statistically significant. Diabetes mellitus was two times more common in controls (28%) than in patients with branch retinal vein occlusion (14%). This difference, however, also did not reach statistical significance (P = 0.13).

CONCLUSIONS

Hyperopia as measured by axial length is not a risk factor for branch retinal vein occlusion. This study provides evidence that hypertension is a risk factor for branch retinal vein occlusion and that chronic open-angle glaucoma and diabetes mellitus are not risk factors for branch retinal vein occlusion.

The relation of surgery for prostatic hypertrophy to carcinoma of the prostate

The authors evaluated the risk of death from prostate cancer in Rhode Island men who had had surgery for prostatic hypertrophy during the years 1959-1970. The retrospective follow-up method was used. Among 4,853 men who had had either a transurethral resection or a prostatectomy, age- and time-standardized mortality from prostate cancer was 1.14 (95% confidence interval (CI) 0.93-1.33) times the rate in the general population of Rhode Island men. The age- and time-standardized mortality ratio was 1.01 (95% CI 0.77-1.31) for men who had had a suprapubic prostatectomy and 1.18 (95% CI 0.94-1.47) for men who had had a transurethral resection. The authors used the case-control method to relate the histologic features of prostatic hypertrophy to subsequent prostate cancer. The observed associations were weak and inconsistent. The results of this study suggest that surgically treated prostatic hypertrophy is not an important determinant of prostate cancer.