[Qualitative analysis on the denervating action of botulinum toxin A in gel].

AIM: To ascertain the bioactivity and to analyse quantificationally the denervating action of botulinum toxin A (BTXA) in gel. METHODS: 36 Sprague-Dawley rats were randomized into four groups. In group A - D, the gastrocnemius muscle of one leg was randomly selected to receive injection of BTXA solution 5U in 0.1 ml, BTXA gel 12.5U in 0.1 ml, BTXA gel 5U in 0.1 ml and BTXA gel 2U in 0.1 ml respectively, while the gastrocnemius muscle of other leg was injected with 0.1 ml of saline solution in group A and 0.1 ml of gel in group B to group D as control. Compound muscle action potential (CMAP) of both gastrocnemius muscles were measured and the amplitudes were recorded before injections, and 5 days, 2 weeks, 3 weeks, 1 month, 2 months and 3 months after the injections respectively. RESULTS: The reduction of CMAP amplitude was significantly different at various time (P < 0.01), and CMAP amplitude decreased significantly after the treatment of BTXA (P < 0.01). The reduction of CMAP amplitude was significantly dif ferent in group A to I) (P < 0.01), and more reduction was found in group A and B (P < 0.01), and the reduction was higher in group C than in group D (P < 0.05). However, there were no significant differences in the reduction of CMAP amplitude between group A and group B. CONCLUSION: Bioactivity of BTXA in gel was showed and the denervating action of BTXA in gel was demonstrated in a dosage and time dependent manner.

[The clinical features and surgical treatment of masked bilateral superior oblique palsy].

OBJECTIVE: To investigate the clinical features, diagnosis and the management of masked bilateral superior oblique palsy (MBSOP). METHODS: Retrospectively analyzed the records of all 7 patients that met the clinical criteria for MBSOP in Zhongshan Ophthalmic Center between 1999 and 2003. The head tilt, vertical deviation in primary position and the action of obliquus pre- and postoperatively were collected in detail. RESULTS: All 7 patients were diagnosed as unilateral SOP in the first time. The average hypertropia in primary position preoperatively was 19.7(Delta) (range 6(Delta) to 30(Delta)). All patients had a head tilt, obvious unilateral inferior oblique overaction (+2 to +4) and mild superior oblique underaction (-1 to -2), and normal action in contralateral superior and inferior obliquus. Initial surgery consisted of ipsilateral inferior oblique weakening with (5 patients) or without (2 patients) ipsilateral superior rectus recession. The average hypertropia in primary position was 12.0(Delta) (range 0(Delta) to 20(Delta)) after the first operation. In 1 week to 4 years, all of the previously masked eye presented the inferior oblique overaction (+2 to +3) and superior oblique underaction (0 to -1). All patients underwent a second surgery in 4 months to 4 years after the initial surgery. The average hypertropia in primary position was 2.3(Delta) (range 0(Delta) to 7(Delta)) after the second operation. Postoperative alignment was excellent in all patients. CONCLUSIONS: Masked bilateral superior oblique palsy is quite difficult to detect before surgical correction of the initial manifest palsy. The possibility of an occult contralateral palsy should be considered in all undergoing surgery for unilateral SOP. The superior rectus recession and the inferior oblique weakening procedure should be performed at different stages. When the masked palsy becomes evident, a successful surgical outcome can usually be expected.

[The effect of weakening the overaction superior oblique muscles on the status of ocular torsion].

OBJECTIVE: To investigate the effect of weakening the superior oblique muscles on the status of ocular torsion. METHODS: Twenty-nine patients (58 eyes) underwent tenotomy or partial ectomy of bilateral superior oblique muscles for treatment of superior oblique overacting. Objective cyclodeviations were assessed by fundus photograph before and 7 days after the surgery. The photographs were transferred to a computer and then the fovea-disc angle was measured by a software for drawing pictures. Subjective cyclodeviations and binocular vision function were assessed by synoptophore. RESULTS: Fundus photography before surgery revealed that the intorsion was 10.48 degrees +/- 6.01 degrees for the right eye and was 9.37 degrees +/- 5.88 degrees for the left eye. The reduction of the cyclodeviations by weakening the superior oblique muscle for the right and left eye was 9.11 degrees +/- 7.09 degrees and 7.94 degrees +/- 4.76 degrees respectively. The comparisons of objective ocular torsion for both eyes showed high significant differences (P < 0.01) pre- and post-operatively. There were no significant differences (P > 0.05) between the effects of tenotomy or partial ectomy of bilateral superior oblique muscles. All patients showed no cyclotropia and normal binocular vision function was obtained with synoptophore before and after surgery. CONCLUSIONS: Weakening the overaction superior oblique could correct ocular incyclodeviation. Both tenotomy and partial ectomy of bilateral superior oblique muscles can treat ocular incyclodeviation effectively. The changes of subjective and objective cyclodeviations are inconsistent with each other.

[Clinical features of V patterns strabismus and its long-term effect of surgical treatment].

OBJECTIVE: To investigate the features and treatment of V patterns strabismus. METHODS: Pre- and post-operative deviation and oblique muscle action as well as binocular visual function were evaluated in sixty-three V pattern patients. The difference between upgaze and downgaze of deviation were recorded before and after operation. RESULTS: Sixty-two patients (98.4%) with binocular or unilateral inferior oblique overaction + 2 to + 3 were treated with inferior oblique weakening procedure and horizontal rectus recession-resection procedure. 1 patient with binocular inferior oblique overaction + 1 treated with horizontal recti recession-resection procedure. The difference between upgaze and downgaze is 25.6 prism diopters (PD) preoperatively and 4.5 PD postoperatively. The primary-position exotropia preoperatively of 48 V pattern exotropia is 37.2 PD, after surgery, the average deviation is 3.4 PD of esotropia [38 cases (79.2%) with deviation within +/- 10 PD]. 15 cases of V pattern esotropia had deviation 50.6 PD preoperatively, after surgery, the average deviation is 2.4 PD of esotropia [11 cases (73.3%) with deviation within 10 PD]. 21 patients (33.3%) obtained stereo visual function after surgery. CONCLUSION: V patterns always had inferior oblique over action and could be treated with the inferior oblique weakening procedure. The primary-position deviation should be treated by traditional horizontal rectus recession-resection procedure. The stereoscopic function had a good prognosis with surgery.

Distribution of the toxin following medial rectus muscular injection of botulinum toxin gel in rabbits.

PURPOSE: To determine the distribution of the toxin among individual muscles after intramuscular injection of botulinum toxin gel. METHODS: One eye of 7 New Zealand white rabbits was randomized into group A, and the contralateral eye was into group B. Eyes in group A received medial rectus intramuscular injection of 2.5 IU of 125I-BTX-A gel in 0.1 ml, and those in group B received equivalent amount of 125I-BTX-A solution by medial rectus intramuscular injection. Four rectus muscles and the levator palpebrae superioris were harvested and the radioactivity of muscles was measured 16 hours after the injection. RESULTS: In group A, the radioactivity of per gram medial rectus was significantly higher than that of other muscles (P < 0.01), and there was no statistically significant difference in the radioactivity of per gram muscles among other muscles (P > 0.05). In group B, the radioactivity of per gram medial rectus and levator palpebrae superioris was significantly higher than that of other muscles respectively(P < 0.05), and the difference in the radioactivity of per gram muscles between medial rectus and levator palpebrae superioris was not statistically significant (P > 0.05). The radioactivity of per gram medial rectus in group A was higher than that in group B (t=3.731, P-0.01), and there was no significant difference in the radioactivity of per gram muscles among other homonymous muscles (P > 0.05). CONCLUSION: The toxin dispersed principally in the injected muscle and the local concentration of the toxin was much high following intramuscular injection of botulinum toxin gel.

Clinical features and surgical treatment of A-pattern exotropia.

PURPOSE: To investigate the clinical characteristics and determine the effective surgical managements of A-pattern exotropia. METHODS: Thirty-two patients with A-pattern exotropia underwent superior oblique muscle weakening procedures, medial rectus resection or (and) lateral rectus recession. Pre- and post-operative eye position, deviation angle, superior oblique function and binocular vision were examined and analyzed in the cases. RESULTS: Overaction of the superior oblique muscles (31/32) and underaction of the medial rectus muscle (20/32) were presented in the cases. Postoperatively, a satisfactory ocular alignment was obtained in 28 cases (87.5%), and the A-pattern was corrected in 31 cases (96.9%). Four cases got binocular vision after surgery. CONCLUSIONS: As one of the most common forms of A and V patterns, A-pattern exotropia showed clinical characteristics of superior oblique muscle overaction and medial rectus muscle underacion, which should be the primary factors in the etiology of A-pattern exotropia, and superior oblique weakening procedures combined with horizontal surgery should be an effective approach to A-pattern exotropia treatment.

[The effect of weakening inferior oblique muscles on the status of ocular torsion].

OBJECTIVE: To understand the clinical significance of subjective and objective examination of cyclodeviations and investigate the effect of weakening inferior oblique muscles on the status of ocular torsion. METHODS: Twenty patients (40 eyes) with overacting inferior oblique muscles underwent bilateral myotomy or partial myectomy of inferior oblique muscles. Subjective cyclodeviations were measured before surgery as well as one week, two months after surgery by double maddox rod test (DMRT). Objective cyclodeviations were assessed by fundus photography before and 7 days after surgery in 15 cases. The photograph was transferred to a computer, and the fovea-disc angle was measured by means of drawing picture software. RESULTS: Nine patients with primary overaction of inferior oblique muscles were negative with DMRT before surgery, and only one case revealed incyclotropia 5.0 degrees tested two months after surgery. Four out of 11 patients with secondary overaction of inferior oblique muscles showed excyclotropia 2.5 degrees - 5.0 degrees with DMRT before surgery, and all patients indicated no subjective cyclotropia with DMRT two months after surgery. Fundus photography determination of the right eye revealed extorsion 16.83 degrees +/- 6.39 degrees, the left eye 14.92 degrees +/- 4.51 degrees before surgery. The reduction of the cyclodeviations by weakening inferior oblique muscle for the right and left eye was 13.07 degrees +/- 3.38 degrees and 10.54 degrees +/- 3.75 degrees respectively. The comparison of objective ocular torsion for both eyes showed high significant differences (P < 0.01) pre- and post-operatively. CONCLUSIONS: The results of subjective and objective examination of cyclodeviations in patients with primary or secondary overacting inferior oblique muscle early after birth were not consistent. Weakening inferior oblique muscle could correct excyclodeviation. There exist complicated compensatory mechanisms for subjective change of ocular torsion after surgery. The changes of subjective and objective cyclodeviations are still inconsistent.

[The effect of preventing anterior segment ischemia by preservation of anterior ciliary vessels in rabbit].

OBJECTIVE: To investigate the effect of preserving anterior ciliary vessels (ACVs) on the prevention of anterior segment ischemia syndrome (ASI) during the surgery of extraocular muscles. METHODS: Thirty-two adult New Zealand white rabbits were randomly divided into four groups. ACVs of the right eyes were preserved among all of the rabbits, and were cut off in all of the left eyes. Group A: internal and external recti were cut off in two eyes; Group B: superior and inferior recti were cut off in two eyes; Group C: internal, external and superior or inferior recti were cut off in two eyes; Group D: all of the recti were cut off in two eyes. All rabbits were observed under slit microscope. The intraocular pressure (IOP), the total protein and lactic acid in the aqueous humor were recorded preoperatively and postoperatively. Eyes were enucleated at the forth week postoperatively to obtain the iris and the ciliary body for histopathologic study and electron microscopy. RESULTS: No signs of ASI were observed in the right eyes of all four groups under the slit lamp and under the light and election microscopes. The IOP and levels of ingredients of aqueous humor (total protein and lactic acid) showed no difference between preoperative and postoperative interval. No obvious ASI was observed in the left eyes of group A. Mild reactions of ASI were observed in the left eyes of group B. Moderate to severe reactions of ASI were observed in the left eyes in group C and group D. The IOP reduced from (17.21 +/- 3.76) mm Hg (1 mm Hg = 0.133 kPa) preoperatively to (14.48 +/- 3.36) mm Hg postoperatively in group C (P < 0.05); and from (16.68 +/- 2.33) mm Hg reduced to(3.17 +/- 0.92) mm Hg in group D. (P < 0.05). The level of total protein and lactic acid in the aqueous humor increased from (505.3 +/- 5.0) mg/L and (7.54 +/- 0.47) g/L preoperatively to (811.9 +/- 44.4) mg/L and (11.00 +/- 3.59) g/L postoperatively in group C, respectively (P < 0.05). In group D, the level of total protein and lactic acid in the aqueous humor increased from (504.6 +/- 4.1) mg/L and (7.17 +/- 1.44) g/L preoperatively to (1025. 8 +/- 78.3) mg/L, (8.23 +/- 1.68) g/L postoperatively, respectively (P < 0.05). There were various histopathological changes under the light and electron microscope in groups C and D. While no obvious ischemic changes were observed in group A. CONCLUSION: Two vertical muscles cut off at one eye simultaneously would produce mild reactions of ischemia, while three or more muscles cut off simultaneously could obstruct blood flow in eyes and induce ASI. Preservation of the ACVs could avoid the occurrence of ASI.

Study on ocular torsion of V patterns strabismus.

PURPOSE: To investigate the ocular torsion of V patterns. METHODS: Twenty-two in hospital V patterns patients underwent bilateral inferior oblique muscles myectomy for inferior oblique overacting and hortizon recti underwent recess-resection procedure to correct hortizon devation. Objective cycloposition was assessed by fundus photograph before and 7 days after surgery in all cases. The photographs was stored in computer, and the disc-fovea angle was measured by means of drawing picture software. As well as the deviation, oblique muscle function was recorded before and after surgery. RESULT: Seventeen cases were bilateral ocular excyclotropia, 4 cases were monocular excyclotropia and one case was annual. The disc-fovea angle of right eyes and left eyes before operation is 15.67 degrees +/- 5.72 degrees and 16.59 degrees +/- 6.69 degrees. The comparisons among V patterns and normal average showed significant differences (P < 0.001). The disc-fovea angle of right eyes and left eyes after operation is 5.24 degrees +/- 5.87 degrees and 7.17 degrees +/- 5.40 degrees. There is no statistic difference between normal average (P > 0.5). The deviation between up- and down 25 degrees is 23.1 +/- 6.8 before surgery, as well as the one is 2.0 +/- 2.25 one week postoperatively. All cases have bilateral inferior oblique overaction, and diminished but one case still has unilateral moderate overaction 7 days after surgery. CONCLUSION: There is objective cyclotropia in case of V patterns, and the objective torsion is normal after weakening overacted inferior oblique muscles.

[Clinical features and surgical treatment of A-pattern exotropia].

OBJECTIVE: To investigate the clinical features of A-pattern exotropia and to evaluate the efficacy of surgical treatment for the correction of A-pattern exotropia (A-XT). METHODS: Pre- and post-operative eye position, superior oblique muscle function, clinical features and binocular function were examined and analyzed in 32 patients with A-pattern exotropia. RESULTS: Overaction of the superior oblique (SO) (31/32) and insufficiency of medial rectus muscle (20/32) were commonly seen in the group of patients. The tenectomy of the SO and the resection of the medial rectus muscle were effective in most of A-pattern exotropia. 87.5% (28/35) of A-pattern exotropia in our study were successfully corrected. Four cases got binocular function after surgery. CONCLUSIONS: Based on the clinical features and the effects of surgical treatment, we conclude that the superior oblique muscle overaction and medial rectus muscle insufficiency are the primary factors in the etiology of A-pattern exotropia that is the most common form of A-V syndrome. Weakening the overaction of superior oblique muscle combined with the correction of exotropia is an effective way to correct A-pattern exotropia.

Experimental study on the prevention of anterior segment ischemia by preservation of anterior ciliary vessels.

PURPOSE: To observe the effect of preserving anterior ciliary vessels (ACVs) on anterior segments of rabbit eyes undergoing tenotomy of extraocular muscles. METHODS: Thirty-two adult New Zealand white rabbits were divided into four groups. Same procedures were done in both eyes in each group except that left eyes underwent preservation of ACVs. In the first group medial and lateral recti, in the second group, superior and inferior recti, in the third group, medial, lateral and superior or inferior recti and in the fourth group, all four recti, underwent tenotomy. Slit-lamp examination, intraocular pressure (IOP) measurement, total protein and lactic acid quantification in aqueous humor were done in all eyes pre- and post-operatively. By four weeks after operation, the eyes were enucleated for histological examination and electron microscopy. All data were analyzed using SPSS version 10. RESULTS: In the left eyes of both group 1 and group 2, no inflammatory response was observed. In the left eyes of group 3 and 4, we observed mild inflammatory response with slit-lamp examination, which disappeared in one wk. However, we did not find significant changes in IOP, total protein and lactic acid of aqueous humor, histology and electron microscopic examination in these groups. In the right eyes in group 2, 3 and 4, we observed moderate to severe inflammatory changes, a few even developed anterior segment ischemia, appeared as decreased IOP, increased total protein and lactic acid in aqueous humor, along with pathological and electron-microscopic changes. CONCLUSION: Simultaneous tenotomy of three or four recti or two vertical recti on one eye may decrease anterior segment blood flow even lead to ischemia. ACVs preservation may protect the blood circulation in anterior segment. Our study suggests that ACVs preservation in strabismus surgeries especially those involving multi-recti tenotomies may prevent potential anterior segment ischemia.

A preliminary report of 40 cases of strabismus microsurgery.

OBJECTIVE: To improve the quality of strabismus surgery and to find out the role of microsurgery in the field of strabismus. METHODS: We performed separation and preservation of anterior ciliary vessels (ACV), adjustable sutures, routine rectus recession, and oblique muscle surgeries under microscope in 13 cases of comitant strabismus, 19 cases of A-V syndrome and 8 cases of paralytic strabismus. RESULTS: Surgeries were performed in a very clear field under microscope. We successfully did vascular microdissection and ACV preservation. Also with the use of microscope, various kinds of strabismus microsurgery videos were recorded. CONCLUSIONS: Microscopic technique can be used to enhance the quality and accuracy of strabismus surgery and to reduce surgical damage, postoperative inflammatory reaction and scar formation. All kinds of strabismus surgery , especially, oblique muscles and complex paralytic operations can be performed under microscope.