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Biomedical subjects

M Gräf

Publications and source records attributed to M Gräf.

46 records · Page 3Linked to original sources
PubMed1994

[Post-traumatic anomalous innervation of the lateral rectus muscle by trigeminal fibers].

BACKGROUND: Congenital or acquired anomalous synkinetic movements are common in Neuro-Ophthalmology. Examples are the Stilling-Türk-Duane syndrome, the Marcus Gunn phenomenon or secondary oculomotor synkinesis in oculomotor nerve palsy. PATIENT AND METHOD: A 29-year-old woman with N.V-, N.VI-, N.VII- and N.VIII-lesion after blunt cranio-cerebral trauma developed a left sided trigemino-abducens synkinesis. The abduction of the left eye by gaze effort was limited to 30 degrees before the midline. With tight jaw closure the eye reached the midline. Eye muscle surgery was performed (recess-resect procedure) because of homonymous diplopia. This is the third published case of a posttraumatic trigemino-abducens synkinesis. RESULTS: Postoperatively the left globe was able to abduct 20 degrees over the midline using maximum coinnervation, with a left exotropia of 5 degrees. Without coinnervation, i.e., without jaw closure an residual esotropia of 26 degrees at distance and 14 degrees at near remained. The utilization of the synkinesis to compensate the esodeviation and to avoid diplopia was hardly possible even after a combined operation for esotropia. It is difficult to determine the amount and type of surgery since one has to take into account that the coinnervation produces an abduction of the eye depending on the intensity of jaw closure. DISCUSSION: The trigemino-abducens synkinesis may be explained by aberrant regeneration of the peripheral never at the temporal petrous bone. Here, aberrant regrowing fibres of the mandibular nerve destined for the masseter muscle may reach the lateral rectus muscle via adjacent distal sheaths of the degenerated proprioceptive fibres of the lateral rectus muscle. Other mechanisms (ephaptic transmission or central reorganisation between the N.V- and N.VI-nuclei in the brain stem) are very unlikely.

Abducens Nerve↗
PubMed1994

[Combined oblique muscle operation with transposition of the insertion in strabismus sursoadductorius].

BACKGROUND: The combined superior oblique tendon tuck and inferior oblique recession is the method of choice for the treatment of congenital and acquired superior oblique muscle palsies with large vertical and cyclodeviations. An additional transposition of the insertions is indicated if the vertical deviation differs greatly from the excyclodeviation. PATIENTS AND METHODS: 38 patients who underwent combined oblique muscle surgery for congenital superior oblique muscle palsy were divided into 3 groups. Group A: 14 patients with small excyclodeviations in spite of large vertical deviations, even after diagnostic occlusion of 3 days. A superior oblique tendon tuck of 5 or 6 mm with transposition of the new insertion to the posterior margin of the original insertion was performed combined with a recession of the inferior oblique muscle of 5 or 6 mm with anterior displacement of 4-6 mm. Group B: 15 patients without a discrepancy between the vertical deviation and the cyclodeviation. They were treated with a conventional superior oblique tendon tuck of 5 or 6 mm combined with a recession of the inferior oblique muscle. Group C: 9 patients without a discrepancy between the vertical deviation and the cyclodeviation, but deviations smaller than in group B. A conventional superior oblique tendon tuck of 6 mm combined with a posterior tenotomy of the inferior oblique muscle was performed. The surgical effect was calculated as the difference between the preoperative deviation after diagnostic occlusion of 3 days and the postoperative deviations (1 week and 3 to 6 months). All angles of deviation were measured subjectively after dissociation of the binocular vision with a dark red filter in front of the fixating, not affected eye at 2.5 m distance using the Harms tangent screen. RESULTS: 3 months postoperatively, the vertical deviation was diminished in primary position by 12.1 degrees/6.8 degrees/6.8 degrees in groups A/B/C, in 25 degrees adduction of the affected eye by 18.4 degrees/13.8 degrees/9.5 degrees. The reduction of the cyclodeviation in primary position was 6.4 degrees/8.0 degrees/5.6 degrees. As a side effect a clinically insignificant, consecutive Brown syndrome occurred in each group. In each group a significant positive correlation between the preoperative deviation and the surgical effect was found. CONCLUSIONS: The combined superior oblique tendon tuck and inferior oblique recession with transposition of the insertions is a suitable method for a selective treatment of the vertical deviation and the cyclodeviation in congenital superior oblique palsy.

Convergence, Ocular↗
PubMed1994

[Effect of axial bulbus length and preoperative squint angle on the effect of horizontal combined squint operations].

We studied the influence of axial bulbus length on the effect of the recession/resection procedure in 175 patients and found a significant negative correlation between the axial length and surgical effect in 62 esotropic patients undergoing surgery of various degrees. A poor correlation was found in 69 exotropic patients. In a group of 54 patients who underwent recession/resection surgery for esotropia with 5 mm recession of the medial rectus muscle and 7 mm resection of the lateral rectus muscle there was a highly significant correlation between the axial length and effect. There was also a significant correlation between the angle of the preoperative deviation and the response to surgery in the esotropic groups. To reduce the variability of strabismus surgery the bulbus length should be taken into consideration, at least in recession/resection procedures when the surgery exceeds 10 mm.

Adolescent↗
PubMed1994

[Effect of bulbus length of reduction of squint angle after suture fixation].

The principle of the posterior fixation suture popularized by Cüppers in 1971 is to decrease the length of the lever arm. The latter depends on the radius of the globe. For geometric reasons the axial length should have an influence on the surgical effect. There are contradictory results on this problem. Therefore, we conducted a study including 112 patients mainly with non-accommodative convergence excess (average age: 7.0 years, average axial length: 21.7 mm). We measured the axial length of both eyes before performing a retroequatorial myopexy. The amount of symmetrical surgery done in both eyes averaged between 12.0 and 14.0 mm, measuring 5.5 mm behind the limbus, i.e., from the insertion of the medial rectus. Fifty of the 112 patients received additional recession or resection of the medial rectus in one or both eyes. A statistically highly significant negative correlation was found between the axial length and the response to strabismus surgery (surgical effect = reduction of near and distance deviation). The correlation coefficient ranged between -0.29 (for all 112 patients) and -0.69 (for the uniform group of 24 patients with 13 mm surgery) with P < 0.0001. The same correlation was evident between the point of the posterior fixation suture behind the equator (angle of "retroequatoriality" in degrees) and the response to strabismus surgery. It is well known fact that larger deviation show a greater response to posterior fixation sutures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[3 cases of vertical accommodative vergence].

Three cases of vertical accommodative vergence have been observed. One patient is described in detail. His right eye had become blind after a trauma. He showed a vertical vergence triggered by accommodation that had not been seen before his loss of sight. The strabismic eye deviated upwards during desaccommodation and downwards during accommodation. This unusual phenomenon could be due to a congenital supranuclear abnormality which became apparent only after the loss of binocular vision.

Accommodation, Ocular↗
PubMed1992

[Reproducibility of the results of two non-contact tonometers. Comparison with the Goldmann applanation tonometer].

Two non-contact tonometers (Keeler "Pulsair" and Reichert NCT II) were compared regarding the reproducibility of their readings mutually and with referring literature about Goldmann applanation tonometry. Differences of maximum 2 mmHg were found using Pulsair tonometer/NCT II in 61%/83% for two subsequent readings, in 73%/89% for subsequent mean values of 3, in 86%/95% for subsequent mean values of 6 and in 97% each for subsequent mean values of 9 readings. The confidence intervals of 90% were +/- 5.87 mmHg/+/- 3.38 mmHg for subsequent readings, +/- 3.75 mmHg/+/- 2.29 mmHg for mean values of 3, +/- 2.63 mmHg/+/- 2.00 mmHg for mean values of 6 and +/- 2.13 mmHg/+/- 1.61 mmHg for mean values of 9 readings, signifying the high scatter of Pulsair measurements; reaching the NCT II's reproducibility, which is comparable to that of the Goldmann readings of an experienced observer, requires mean values of a higher number of Pulsair readings. The discreet pressure lowering effect occurring with repeated NCT II applications could not be observed during Pulsair measurements. Perhaps the Pulsair instrument might be interesting for scientific questions, but it is not recommendable for routine diagnostic.

Equipment Design↗
PubMed1991

[Significance of the corneal thickness in non-contact tonometry].

In this study the Reichert non-contact tonometer (NCT II) was compared with the Goldmann applanation tonometer (GAT) in 25 subjects (50 eyes; pressure range 9-17 mmHg). The relationship NCT/GAT fulfilled the conditions required for legal verification. Marked differences between the readings of both instruments can be caused by anomalous central corneal thickness, because non-contact tonometry is influenced more than conventional applanation tonometry by the corneal thickness. Starting from a central thickness of 0.51 mm, the NCT is assumed to underestimate the actual intraocular pressure in eyes with thinner and to overestimate it in eyes with thicker cornea by 1 mmHg per 0.01 mm difference of corneal thickness. This value changes with individual corneal tissue qualities and is not valid especially in presence of corneal edema.

Adult↗
PubMed1990

[Pre- and postoperative non-contact tonometry].

The AO II non-contact tonometer (NCT) was compared with the Goldmann applanation tonometer (GAT) in 50 patients preoperatively and on the first day after cataract surgery. After pooling the preoperative and postoperative values, the relationship between NCT (y axis) and GAT (x axis) was described by the following regression: y = 1.01x - 0.69, where 1.01 is the slope and -0.69 (in mm Hg) is the y intercept of the regression line. The standard deviation (SD) in relation to the regression line was 2.19 mm Hg (y values). After separating the preoperative (n = 100; pressure range 6-21 mm Hg) and postoperative values (n = 47; pressure range 6-30 mm Hg) the following equations were obtained: preoperatively: y = 0.89x + 0.82 (SD 2.2 mm Hg); postoperatively: y = 1.06x - 1.15 (SD 2.24 mm Hg). Since the postoperative regression line comes close to that required for legal verification, the NCT may - with limitations - also be recommended for measuring IOP after cataract surgery. Both preoperatively and postoperatively, a significantly linear relationship was found between corneal thickness and the difference GAT minus NCT readings. This implies that in normal eyes with thin corneas the NCT tends to underestimate IOP, while in eyes with thick corneas there is a tendency to overestimate IOP. Even slight corneal edema (postoperatively) reduces this effect.

Cataract Extraction↗
PubMed1988

Evaluation of (E)-5-(2-bromovinyl)- and 5-vinyl-1-beta-D-arabinofuranosyluracil (BrVaraU, VaraU) in the treatment of experimental herpes simplex virus type 1 keratitis in rabbits: comparison with (E)-5-(2-bromovinyl)-2'-deoxyuridine (BrVUdR).

The 5-substituted 1-beta-D-arabinofuranosyl (araU) analogues, (E)-5-(2-bromovinyl)-araU (BrVaraU) and 5-vinyl-araU (VaraU), which can be considered as structural analogues of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BrVUdR), are potent and selective inhibitors of herpes simplex virus type 1 (HSV-1) replication in vitro. BrVaraU and VaraU have been compared with BrVUdR for their therapeutic effect on acute HSV-1 keratitis in rabbits. Both araU derivatives applied as 0.1% eyedrops suppressed the development of keratitis as monitored by the reduced number of herpes efflorescences. The healing effect of BrVaraU and VaraU was less pronounced than that of 0.1% BrVUdR eyedrops, the difference between BrVUdR and VaraU being statistically significant at the 10th day of treatment. As a further indication of the healing effect the number of cornea with opacities seen after cessation of drug treatment were 3.3, 7.4, 27.6 and 46.9% for the BrVUdR-BrVaraU-, VaraU- and placebo-treated eyes, respectively.

Animals↗