Monocular Slanted Lateral Rectus Recession for Exotropia with Convergence Insufficiency

PURPOSE: To evaluate the efficacy of monocular slanted lateral rectus (LR) muscle recession for exotropia with convergence insufficiency. METHODS: Twenty five patients with exotropia greater at near than at versus far distance by > or =10 prism diopters (PD), were divided into two groups: 15 patients who underwent monocular slanted LR recession (study group), and 10 patients who underwent monocular standard LR recession (control group). In the study group, the lower horn of the LR was recessed according to near deviation, the upper horn was recessed according to distance deviation. In the control group, monocular LR was recessed according to distance deviation. The postoperative ocular alignment at distance and near, and the difference between them, were measured and compared retrospectively. The criteria for successful outcome were postoperative residual deviation at near and distance, and the difference of 8 PD or less between the two. RESULTS: The mean distance deviation showed a significant postoperative reduction in both groups (P<0.001, P<0.001). The mean near deviation showed a significant postoperative reduction in both groups (P<0.001, P<0.001). The mean difference between near and distance deviation showed a significant postoperative reduction only in the study group (P<0.001, P=0.175). Successful outcome was obtained in 13 our of 15 (86.7%) patients in the study group, in 2 out of 10 (20%) patients in the control group. None of the study patients had postoperative diplopia. CONCLUSIONS: Monocular slanted lateral rectus recession is effective in reducing both distant and near exodeviation and in collapsing the difference between distance and near deviation them at postoperative 4 months.

Adjustable Suture Technique in Pediatric Strabismus with Ketamine Anesthesia

Adjustable suture technique may be indicated for strabismus surgery when the surgical outcome will be uncertain. We used ketamine intramuscular injection for sedation the day, and performed adjustment after the surgery to enhance the postoperative success rate. The results were analyzed. The average age of the 29 pediatric patients was 53.5 +/-21 months and they were devided into 22 exotropia group and 7 esotropia group. The minimal postoperative observation period was 3 months(average 4.2+/-1.6 months). Among 22 exotropia patients, 13 patients were adjusted and the advancement amount was 1~2 mm. Esotropia was not adjusted. In the final follow-up evaluation, 19 exotropic patients(86.4%)and 7 esotropic patients showed the favorable outcome. However, 3 exotropic patients failed. Two were overcorrected and 1 was undercorrected. In 1 overcorrected case, the postoperative V pattern esotropia occurred. When the alignment can be measured and the picture of external eyes can be obtained, postoprative adjustment was possible after ketamine intramuscular injection. Since the degree of preoperative alignment and the precise evaluation of preadjustment alignment play an important role in determining the advancement amount, careful evaluation should be performed.

Clinical Analysis of Congenital Exotropia

Constant exotropia is uncommon during the first year of life.We investigated characteristics, surgical outcome and associated ocular abnormalities in patients who had an exodeviation during the first year of life. The charts of 18 patients who were diagnosed as congenital exotropia before 1 year old were reviewed.We etrospectively analyzed 10 healthy patients who did not have associated systemic or ocular abnormalities and were followed for at least 3 months after surgery. The mean follow-up period was 1.2 years[range, 3 months to 3.5 years]and all of them had an exodeviation of 25 prism diopter[PD]or more[mean, 37.5PD, SD 10.6PD].Preoperative DVD and inferior oblique muscle overaction were found in 1 patient respectively. Surgery was performed in 9 cases and botulinum toxin was injected in 1 case.Seven patients[70%]showed stable alignment within 10PD with one operation and one patient required reoperation.Postoperative dissociated vertical deviation and inferior oblique muscle overaction were found in each 1 patients. Congenital exotropia has large deviation and may be associated with inferior oblique muscle overaction or dissociated vertical deviation as infantile esotropia and has stable alignment with single operation.But unlike infan-tile esotropia, nystagmus is extremely rare.

A Histopathological Study on the Production of Exfoliation Material in Eyes with Exfoliation Syndrome

The hallmark of exfoliation syndrome is the appearance of white granular deposits and dandruff-like flakes on the lens,iris and angle. The incidence of glaucoma is high,and due to zonular weakening, complications are likely to occur in cataract surgery. A histopathological study with electron microscopy was performed on the iris and conjunctival tissue in order to clarify the production process of exfoliation material in the eyes with exfoliation syndrome. The materials were obtained from 13 eyes with exfoliation syndrome during surgery for glaucoma or cataract. The clumps of microfibrils were observed in the extracellular matrix, and the exfoliation materials were closely related with microfibrils.It was found that the basic unit of the exfoliation materials was microfibril. The cellular degenerations were observed in the basement membrane of capillary endothelium, especially the cells near the iris vessels. The exfoliation materials were observed around the degenerated cells; the mature or immature exfoliation materials around the iris melanocyte which show the various degrees of degeneration. The more degeneration and melting of the cells, the larger amount of exfoliation materials. This study suggests that the exfoliation materials in the eyes with exfoliation syndrome are derived from the abnormal microfibril, abnormal basement membrane, and degenerated cell itself.

Bilateral Medial Recti Recession in Infantile Esotropia

Twenty-seven patients with congnital esotropia underwent bilateral medial recti recessions and were follwed up for 6 months or more. The relationship between the amount of bilateral medial rectus recession, the pre- and postoperative alignment was analyzed. The success of sugery was defined from the undercorrection less than 10 prism diopter(PD) to the overcorrection less than 5PD. Nineteen of 27 patients(70.3%) were successful. 3 patients(11.1%) were undercorrected and five(18.5%) were overcorrected. Three patients who showed overcorrection more than 20PD were recessed 7mm or more. The standard deviation of postoperative alignment was 2.2 in patients with preoperative alignment less than 50PD, and 17.4 in those with 50PD or more. The difference was significant(p<0.05). When preoperative alignment was 25 to 55PD and the amount of surgery was 4 to 7mm, there was high linear correlation between the amount of surgery and the corrected angle. However, close observation for consecutive exotropia will be necessary when preoperative alignment is more than 50PD and the amount of recession is more than 7mm.

Result of Initial Botulinum Toxin Injection in Childhood Horizontal Strabismus

Thirty one children with horizontal strabismus in age less than 10 years were treated with botulinum toxin type A(Botox) injection of extraocular muscles. We have analyzed the effects and complications of injection in twenty five patients for whom follow-up of 3 months or more was available. Preinjection alignment was 25+/-11 prism diopter(PD) in exotropia and 35+/-10PD in esotropia. The average time of maximal effect was 1 week after injection and the average time to achieve orthotropia 2 to 3 months after injection. At three months after injection, the alignments in fifteen patients(60%) were 10 prism diopter(PD) or less, in eight between 10 and 20PD, and in two more than 20PD. Success rate was high when limitation of eye movement was obvious(> OR = -2) at 1 week after injection. The most common complications were ptosis presented in fifteen patients(60%), subconjucntival hemorrhage in eight, abnormal head position in seven, vertical strabismus in seven and disorientation in one. Initial injection of botulinum toxin showed poorer results compared to surgery in childhood horizontal strabismus but did not show severe complications except undercorrection. Toxin injection can be an alternative choice of strabismus management but more prolonged follow-up will be needed.

Histologic Study for Effect of Experimental Hematoma on Extraocular Muscle

This study was performed to evaluate the effect of hematoma which often occurred during the strabismus surgery on the extraocular muscles. We created focal hematomas around the superior rectus mascles of three dogs by rupture of the anterior ciliary artery. One, two and four weeks after formation of the hematoma respectively, we resected the superior rectus muscles 7mm in length at the site of previous hematoma and histopathologic examination with a light microscope was performed. We could not find any specific pathologic change in the muscular fiber in one week after surgery. But, focal degeneration of the muscle fiber was found in that of two weeks and diffuse degeneration in that of four weeks after surgery. However, any fibrotic lesion was not found. The muscle degeneration may be caused by the pressure of hematoma and ischemia due to small arterial occlusion.

Consecutive Esotropia after Surgery for Intermittent Exotropia

We evaluated retrospectively the clinical characteristics of 10 esotropic patients following surgery for intermittent exotropia. The nonoperative group(NG) comprised of 5 patients with esodeviation under 16PD and the operative group(OG) of 5 patients with the angle of 18PD or more. The associated condition was one case of myopic anisometropia in the NG. In the OG, there were inferior oblique overactions in three cases and high myopia or amblyopia in two cases. The mean esodeviation at early stage was 11.8PD and 7.8PD at final stage in the NG. 4 of 5 patients showed good alignment within 10PD. In the OG, the mean early esodeviation and final deviation were 11.6PD and 19.2PD respectively. Three patients showed orthotropia in the early stage, and 2 patients revealed orthotropia in the final stage. There were no significant differences in achieving fusion and steropsis between the two groups. The results suggest that the degree of deviation and associated ocular conditions will influence the choice of therapy. We think that there will be no problem in the recovery of binocular visual function after surgery for consecutive esotropia.

Analysis of Abnormal Heal Posture and Surgical Results in the Patients with Duanes Retraction Syndrome

We evaluated retrospectively the clinical records of 46 cases of Duanes retraction syndrome. The purpose of this study is to demonstrate a clinical characteristics of this syndrome and improvement of abnormal head posture and degree of deviation in 14 cases undergoing operation. Unilateral manifestation was in 42 cases and 4 cases were involved bilaterally. Left eye was involved predominantly in 29 cases (63.0%). The frequencies analyzed according to Hubers classification were that Type I was 64.3%, Type II 7.1%, and Type III 28.6% in unilateral cases. Of unilateral cases, compensatory face turn was exhibited in 65.2% of Type I, 100% of Type II, and 60.0% of Type III. In primary position, 44.4% of Type I had esodeviation, and 100% of Type II ad 83.3% of type III had exodeviation. The major concerns of most patients or their parents were the correction of strabismus and gaze limitation, but they hardly recognized abnormal head posture. The correction of abnormal head posture and strabismus was achieved in 78.6% postoperatively.

Artifact of Worth Four Dot Test in Strabismic Patients

It is the purpose of this study to evaluate fusional status of 49 strabismic patients who showed orthophoria less than 10 prism diopters (PD) after surgery under alternate prism and cover test. We undertook the Worth 4-dot(W4D) test twice, reversing the position of the red/green glasses between the eyes for the second trial. Bagolini test was also performed in 31 of 49 cases. Nineteen of 49 case(18.4%) showed different results on the W4D test with red/green glasses after reversal at near or distance, either changing fusional status or changing laterality of suppression. Four of 31 cases (18.0%) showed different status of fusion or suppression between W4D and Bagolini tests. We think that it repeating test twice, with the red/green glass reversed between trials, and with combination of Bagolini test, provides better reliability of W4D test.

Distance Stereoacuity in Children with Intermittent Exotropia Using B-VAT II Video Acuity Tester

The purpose of this study is to determine if distance stereoacuity could be used as an objective means of assessing control in intermittent exotropia. We evaluated distance stereoacuity in 37 patients with intermittent exotropia showing orthophoria postopratively using the Mentor B-VAT II Videoacuity tester. All patients had fusion at near but 14 of 31 patients(38%) had fusion at distance preoperatively. The mean preoperative distance stereoacuities were 216 seconds with binocular vision circle(BVC) and 351 seconds with binocular vision random dot E(BVRDE) ( p=0.0002). The postoperative improvement was statistically significant with BVC(p=0.001), not statistically significant with BVRDE(p=0.7). On our results it seems to be easier to know BVC than BVRDE in children. It suggests that the BVC is a useful test for assessing control in intermittent exotropia.

Clinical analysis of Superior Oblique Plication Procedure

The purpose of this study is to evaluate retrospectively the surgical results and complications in the patients with unilateral superior oblique palsy using superior oblique plication(SO plication) only or SO plication combined with inferior oblique weakening. Among 22 patients with unilateral superior oblique palsy, there were 13 patients(59.1%) in type III, 5 patients(22.7%) in type IV, 2 patients(9.1%) in type II and 2 patients(9.1%) in type V according to Knapps classification. The mean amount of hypertropia was 18 prism diopters(PD) and 18 of 22 patients(81.8%) showed abnormal head posture(AHP). Nineteen patients (86.4%) showed horizontal strabismus and exotropia was most common. The methods of oblique and vertical rectus operation were SO plication, SO plication combined with inferior oblique weakening, combined with resection of inferior rectus, and combined with recession of contralateral inferior rectus, inferior oblique weakening, and superior rectus weakening. We performed corrective surgery on the patients with horizontal deviation more than 14 PD. Postoperatively the mean amount of hypertropia was 2.6PD. In 7 patients with superior oblique plication only the mean amount of correction in plication was 8.4PD, and hypertropia was corrected 1.2PD per mm. Thirteen of 18 patients(72.2%) with AHP and 15 of 19 patients (78.9%) with horizontal strabismus were corrected after operation. Postoperative complications were residual hypertropia in 7 patients(31.8%) and Brown syndrome in one. We conclude that plication of the superior oblique may be one of the effective procedures for correction of superior oblique palsy and possible its complications may be postoperative undercorrection and Brown syndrom.

The Role of Preoperative Indirect Ophthalmoscopy Under General Anesthesia for Diagnosis of Torsional Strabismus

The purpose of this study is to evaluate the status of fundus torsion in 48 patients with unilateral inferior oblique overaction(IOOA) and the results were compared with that in 182 patients who showed normal inferior oblique function by an indirect ophthalmoscope under general anesthesia before strabismic surgery. In 48 eyes with unilateral IOOA, 35 eyes(72.9%) showed extorsion in the same eye. We could also find extorsion in 9 normal fellow eyes(18.7%). Among 182 horizontal strabismic patients(364 eyes) with normal inferior oblique function, there were 23 eyes(6.3%) of extorsion and 1 eye (0.3%) of intorsion. We compared the degree of extorsion with that of IOOA in 48 patients with unilateral IOOA: a mild extorsion were observed in 2 of 10 eyes with IOOA+1. A mild and moderate extorsion were observed in 13(72.2%) and 3 (16.7%) of 18 eyes with IOOA+2, respectively. A mild and moderate extorsion were observed in 9(45%) and 8(40%) of 20 eyes with IOOA+3 respectively. These findings showed that the greater IOOA produces the greater extorsion(p<0.01). On our results the fundus indirect ophthamoscopy before strabismic surgery seems to be helpful in the diagnosis of cyclotorsion.

The Effectiveness of Photorefraction for the Screening of Amblyogenic Factors

It is the purpose of this study to evaluate the effectiveness of MTI photoscreener(using the eccentric photorefraction principle) by comparing the sensitivity and specificity between the refractive errors determined by MTI photoscreener and cycloplegic refraction in 5 to 6 year-old children in the kindergartens. Pass/fail screening data was determined by the two masked observers, and compared with the results of cycloplegic refraction. And, the statistical analysis was done. There was some differences in the sensitivity rate between the two examiners. Two cases of anisometropia and one media opacity were found by the two observers, respectively. The sensitivity rate was 70%, specificity rate 90%, overall correlation rate 87%, positive predictive value 52% and negative predictive value 95% in the combined results by the observer A and B. The results of our study suggest that MTI photoscreener may be a reliable mass-screening method of detecting amblyogenic factors(refractive error, etc) in the preschool children although the sensitivity rate is slightly variable.

Surgical Results of Unilateral and Bilateral Lateral Rectus Recessions in Exotropia under 25 Prism Diopter

It is the purpose of this study to compare the postoperative results of surgery for 39 patients with exotropia under 25 prism diopters (PD). Two surgical methods were done; 8 to 9mm unilateral recission of the lateral rectus muscle in 17 patients (unilateral gruop) and 4 to 6mm bilateal recession in 20 patients (bilateral group). The preoperative deviations on the average were 20.8PD in unilateral and 22.6PD in bilateral grou, and postoperatie corrections on the average were 16.5PD in unilateral and 22.8PD in bilateral group. The 41.2% in unilateral droup and 59.1% in bilateral group were under +/-5PD in postoperative deviation. There were 12 cases (70.6%) in unilateral and 20 cases (90.9%) in bilateral group showing the amount of deviation less than 10PD of under or overcorrection. InBilateral group, higher success rate was observed, but there was no statistical difference (p=0.053) between the two groups. The limitation of abduction was observed in the 4 cases of unilateral group but there was no significant cosmetic problem. From our surgical results, the outcome of the bilateral recission for the lateral rectus muscle is better than that ofthe unilateral recession for the correction of exotropia under 25PD although there was no statistical difference.

Clinical and Histological Study of Extraocular Muscle in Congenital Fibrosis Syndrome

The authors analyzed 8 cases of the patients with congenital fibrous syndrome for clinical and histological study. In addition we observed the histological findings for the relationship between the clinical manifestations and fibrosis of the muscles and the cause of the fibrosis. All of the patients had hypotropia and 7 of whom had bilateral tendency, six patients showed exotropia and two patines showed esotropia. Associated ocular problems were amblyopia (88%), ptosis (88%), nisometropia (50%) and nystagmus (62%). The most common abnormal head posture was chin up position (88%). There were improvement of abnormal head position in six patients but no change of abnormal head posture in two patients after operation. In histological study the muscle fiber showed generalized degeneration. Clumping of the nuclei of the muscle fiber was replaced by many nuclei of the fibroblasts in light microscopy. The authors observed the proliferation of the collagen fibers among the fibroblastic nuclei and amorphous diffuse particle stained by lightred color in the intercellular space. In electron microscopy the premature collagen fibers appeared among amorphous particles and some particles had close relationship with collagen fibers. From these findings, it would appear that formation of the collagen fiber occurs in extraocular space and degenerated myofibrils are responsible for the formation of the collagen fiber, and abnormal head posture results from fibrosis of muscle fiber and ptosis.

Posterior Tenotomy and Tenectomy of Superior Oblique Muscle in "A" Pattern Strabismus

In 7 patients with "A" pattern strabismus with superior oblique overaction, we performed superior oblique posterior tenotomy and tenectomy(PTT) and horizontal rectus muscle surgery for horizontal strabismus, uni- or bilaterally, and analysed the status in degree of postoperative correction of "A" pattern, horizontal and vertical deviation in the primary position for availability of PTT in correction of superior oblique overaction. The average correction of "A" pattern was 10.4 prism diopter(PD). 6 of 7 patients showed eso- or exotropia under 6 PD in the primary position. Two of four patients in bilateral surgery and 2 of 3 patients in unilateral surgery showed the change of vertical deviation in the primary position but there were no problems cosmetically except one. From these results, we think that posterior tenotomy and tenectomy of superior oblique muscle is one of the useful methods for correction of superior oblique overaction in "A" pattern strabismus.

Study for Reversibility on Myopathy of Extraocular Muscle after Subconjunctival Injection of Gentamicin(R) in Rabbit

Subconjunctival injection of gentamicin(R)(GM) can cause an acute myopathy of the extraocular muscles. The purpose of this study is to demonstrate the effect of various dosage of GM and reversibility of tissue changes after subconjunctival injection of GM with 10m/ml, 20mg/ml and 40mg/ml each rabbit respectively. We obtained the superior rectus at 1 day, 1 week, 4 weeks and 12 weeks after injection and examined the specimens by light and electron microscopes. On 1 day, light microscopy showed inflammatory change with polymorphonuclear leukocytes and monocytes on 1 week. The higher the concentration of GM was, the more marked inflammation and degeneration of the muscle fibers were. The control group was normal. On 4 weeks there were markedly regenerated muscle fibers with focal degeneration. On 12 weeks there were nearly normal finding of the muscle with some degeneration. On 1 day and 1 week, electron microscopy showed various degrees of degeneration of the muscle fibers. On 4 and 12 weeks the muscle fiber showed satellite nucleus, deposit of abundant Golgi networks, increased numbers and enlargement of mitochondria with some degeneration. On early stage of injecton with normal saline, some vacuoles were seen in the control group. Our results suggest that gentamicin-induced myopathy is dose-related and reversible in histological aspect.

The Factors Affecting Consecutive Exotropia with Angle of 20 Prism Diopters or More following Surgery for Esotropia

The purpose of this study is to evaluate the factors that may have a role in the development of postoperative exotropia with the angle of 20 prism diopters (PD) or more. The study group was subdivided into three groups depending on the amount of deviation for consecutive exotropia; group A is the angle of 20PD or more, group B is between 10PD and 18PD, and group C is orthophoria. Comparing group A with C, the presence of amblyopia(p<0.05), postoperative limitation on adduction(p<0.01), postoperative binocular vision(p<0.05) and postoperative A or V pattern(p<0.05) were statistically significant. Among the factors of group A and B, the presence of postoperative limitation on adduction(p<0.05) and refractive error of 3D or more(p<0.05) were signifi cant. We suggest that these factors may have a role to develop large consecutive exotropia, therefore close observation is necessary when these factors are found.

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.