Trypan Blue-Assisted Measurements of Anatomical Positions of the Superior Rectus Muscle and Superior Oblique Muscle in Enucleated Eyes

PURPOSE: To recognize the anatomical positions of the superior oblique muscle in enucleated eyes using trypan blue. METHODS: Twenty-two surgically-enucleated eyes of 11 bodies were studied. The shortest distance from the nasal insertion of superior rectus to the anterior end of the superior oblique tendon, the distance from the temporal insertion of superior rectus to the anterior end of the superior oblique insertion, and the greatest width of superior oblique tendon insertion were measured by caliper 3 consecutive times. The average values in each of the above 3 points were calculated, and values prior to and after trypan blue staining were compared. RESULTS: Prior to staining with trypan blue, the average distance from the nasal insertion of superior rectus to the anterior end of the superior oblique tendon was 4.97 mm and the average distance from the temporal insertion of superior rectus to the anterior end of the superior oblique insertion was 7.57 mm; after staining with trypan blue, the average values were 5.09 mm and 7.65 mm, respectively. There was no statistically meaningful difference in values prior to and after staining (p > 0.05). Prior to staining, the average value of the greatest width of the superior oblique tendon was 10.32 mm, and after staining with trypan blue, the average value increased to 10.76 mm. There was a statistically meaningful difference between the values (p = 0.02). CONCLUSIONS: Trypan blue staining helped to recognize the location and the width of the superior oblique tendon more precisely.

Surgical Outcome of Vertical Rectus Muscle Recession in Hypertropia

PURPOSE: To determine the extent of vertical rectus muscle correction in hypertropia showing good prognosis. METHODS: A retrospective study was performed with a total of 16 patients who underwent superior or inferior rectus muscle recession surgery with a follow-up of more than 6 months. Vertical muscle recession of 1 mm per 2.5 to 3.0 prism diopters was performed according to the surgeon's discretion. RESULTS: At 1 week after surgical correction, undercorrection, orthophoria, and overcorrection was observed in 4, 7 and 5 cases, respectively. At the final examination, ocular deviation was decreased in the undercorrected cases and maintained orthophoric except in 1 case where only a small amount of deviation recurred. However, in the cases of postoperative overcorrectionn, ocular deviation increased; 2 cases required surgical correction for consecutive hypertropia. CONCLUSIONS: When performing vertical rectus muscle recession in primary hypertropia, the amount of correction for orthophoria or undercorrection should be determined.

The Surgical Correction of Vertical Deviation after Superior Rectus Muscle Recession in Patients with Hypertropia

PURPOSE: In general, the amount of vertical rectus surgery is based on achieving 3 prism diopters (PD) of realignment for each millimeter of muscle recession. The study aimed to determine the surgical correction of vertical deviation in patients with hypertropia after superior rectus muscle recession. METHODS: A total of 32 patients with hypertropia underwent 2-8 mm recession of the superior rectus muscle. The average surgical correction for each millimeter of recession was calculated by deducting the post-surgical deviation from the pre-surgical vertical deviation and dividing the remnant by the amount of recession (mm). RESULTS: The average surgical correction was 2.2 +/- 0.7 PD for each millimeter of superior rectus recession. There was no statistical significance in the change in surgical correction in terms of follow-up period, which was categorized as one day, one, two, and six months, and one year (P>0.05). The relationship between surgical correction and age (below and above 11 years old), gender or the amount of recession (below or above 5 mm) was not statistically significant (P>0.05). There was no statistically significant difference in vertical correction between esodeviation and exodeviation (P>0.05). CONCLUSIONS: The study showed an average surgical correction of vertical deviation of 2.2 PD for each millimeter of superior rectus muscle recession. The results suggest that increased recession, within the maximum limit of 8 mm, is an effective approach to prevent undercorrection for children who have hypertropia but cannot undergo adjustable strabismus surgery.

Tensile Strength of Musculoscleral Insertion after Superior Rectus Recession on Rabbit

PURPOSE: The author performed this experimental study to investigate the changes in the tensile strength of a new insertion following a superior rectus recession in a rabbit's eye. METHODS: Conventional superior rectus muscle recession procedures with the hang-back suture technique were performed on New Zealand white rabbits (body weight 2~3kg), after which the disinsertional force was measured using a digital tension gauge on the 3rd, 5th, and 7th days, and then weekly for up to 8 weeks postoperatively. RESULTS: The postoperative disinsertional forces were as follows: 38.25 +/- 2.75, 165 +/- 31.27, and 167.25 +/- 26.99 g at the 3rd , 5th and 7th days, and 211.00 +/- 25.66, 222.75 +/- 26.66, 255.25 +/- 24.51, 271.50 +/- 38.25, 429.50 +/- 21.14 g at the 2nd, 3rd, 4th, 6th and 8th weeks respectively. The disinsertional forces linearly increased with the postoperative time period and there was a strong correlation with correlation coefficient being 0.903. CONCLUSIONS: We concluded that musculoscleral adhesion with hang-back suture maintained enough strength in early postoperative time period.

A Case of Simultaneous Injury to Ipsilateral Superior Rectus and Superior Oblique Muscle

PURPOSE: Because the ipsilateral superior rectus (SR) and superior oblique (SO) muscles are innervated by two different nerves, it is very rare for these two muscles to be paralyzed while all other extraocular muscles function normally. The authors experienced a case where the patient had a loss of intorsion (action of both SR and SO muscles) and also loss of SO muscle's infraduction and adduction, and SR muscle's supraduction and abduction. The authors studied how such loss of function affects extraocular movement. METHODS: A 63-year-old male patient who had his SR and SO muscles severed by a saw was admitted to the hospital after getting rid of the two exposed muscle which were attached to the eyeball due to failure of reconstruction of two muscle. The patient was followed up for 8 months, and at the end of the follow-up period, the angle of deviation was measured while double Maddox test and fundus examination were also performed. RESULTS: At primary position there was extorsion of 7 degrees as well as esodeviation of 6 PD and hypodeviation of 6 PD on the left eye, and we hereby report the case.

Clinical Evaluation of Ptosis after Scleral Buckling

We evaluated the degree of ptosis, the function of levator muscle, and postoperative interval to recovery of ptosis in 20 patients who underwent scleral buckling for retinal detachment. The MRD 1(Margin reflex distance 1), function of levator muscle by Berke method and interpalpebral fissure height were evaluated at preoperative day and 1, 3 days, 1, 2, 4, 6, 8, weeks, and 6 months after surgery. The results were compared according to age, gender, extent of buckling, location of buckle. All patients were reported to develop ptosis at postoperative day one, and 20% of them showed mild ptosis persistent until 8 weeks after surgery. The decrement of MRD 1 was statistically significant until postoperative 2 weeks, but impaired function of levator muscle was statistically significant until postoperative 6 weeks(P<0.05). The postoperative interval to recovery of MRD 1 was delayed in group of old age(order than 40 years), in male and when the buckle was located under the superior rectus muscle(P<0.05). The postoperative interval to recovery of function of levator muscle was delayed in group of female, when the buckle extent was more than 180 degrees and when the buckle was located under the superior rectus muscle(P<0.05).

Superior Rectus Recession with Modified Hang-loose Technique in Rabbits

Hang-loose technique(HLT) is a reliable recession method in strabismus surgery. However, the loop length and the parallel of the anterior muscle border may not be sustained when the muscle was recessed behing the equator. This study was designed to assess the postoperative status of the large-recessed superior rectus muscle using the HLT and a modification of HLT(M-HLT) respectively in rabbits. Some of the recessed muscles with both techniques showed forward creeping. The average creeping was 0.5 mm on M-HLT and 1.1 mm on HLT in 7 mm recession group, and the difference was statistically significant(p=0.023). In 8 mm recession group, the average creeping was 1.0 mm on M-HLT and 1.8 mm on HLT. The difference was statistically significant(p=0.012). Although the parallel of the anterior muscle border was better on HLT than on M-HLT, the difference was not significant statistically. According to our result, M-HLT may be an useful alternative method in the cases of large recession with HLT.