The Accuracy of Estimating Postoperative Deviation in Exotropia With over 40 Prism Diopters

PURPOSE: To assess the accuracy of estimating postoperative deviation in large-angle exotropia over 40 prism diopters (PD). METHODS: A retrospective analysis was performed on 61 exotropia patients with over 40 PD exotropia who had undergone 2-muscle surgery by two surgeons and with at least 6 months follow-up. The accuracy was assessed by analyzing the discrepancy between preoperatively predicted residual deviation and deviation at postoperative 6weeks. Successful surgery was defined as deviation within +/- 10 PD at the last postoperative visit. RESULTS: More accurate residual deviation was predicted in exotropia with prism diopters between 40 and 59 (97.8%) than in exotropia with 60 PD or more (62.5%). And there was no significant difference between two surgeons. Surgical success rates at six months and one year after surgery were 96.8%, 94.7% in exotropia with 40 to 49 PD, 71.4%, 60.0%, 50 to 59 PD, 50.0%, 45.5%, 60 PD or more, respectively. There were four patients of whom the postoperative deviation angle exceeded more than 10 PD of the estimated deviation. CONCLUSIONS: The accuracy of estimating residual deviation prior to surgery was higher and more successful surgery was achieved in exotropia ranging in 40 to 59 PD than in exotropia with 60 PD or more. Therefore, 2- muscle surgery will be suitable for large-angle exotropia with less than 60 PD.

Reunion of the Rabbit Superior Oblique Tendon After Weakening Procedures

PURPOSE: To investigate the degree of reunion in rabbit eyes of the superior oblique tendon after several surgical weakening procedures. METHODS: A total of 32 rabbits (64 eyes) were used in this study. The rabbits were randomly assigned to four groups, eight rabbits (16 eyes) in the tenotomy group, eight rabbits (16 eyes) in the tenectomy group, eight rabbits (16 eyes) in the disinsertion group and eight rabbits (16 eyes) in the recession group. The degree of reunion or reattachment of the superior oblique tendon on the globe were examined on four eyes in each group at postoperative weeks two, four, six and eight. RESULTS: At eight weeks, the newly created insertion site remained at the same site in all eyes in the recession group, and the distal end of the superior oblique tendon was reattached at the medial border of the superior rectus muscle in all four eyes in the tenotomy and disinsertion groups, and in three of four eyes in the tenectomy group. CONCLUSIONS: From this experimental study, it was speculated that superior oblique recession is more effective than other superior oblique weakening procedures. This result could be helpful in the prediction of time of recurrence for superior oblique overaction after superior oblique weakening procedures.

Comparison of the Stability of Postoperative Alignment in Sensory Exotropia: Adjustable Versus Non-Adjustable Surgery

PURPOSE: To compare the success rates and stabilities of postoperative alignment between adjustable and the non-adjustable surgeries in the treatment of sensory exotropia. METHODS: A retrospective analysis was performed on all patients with sensory exotropia who had undergone unilateral lateral rectus recession and medial rectus resection (R&R) between January 1998 and August 2005. Thirty-four patients underwent conventional R&R, and 20 patients underwent R&R with adjustable suture of the lateral rectus. The surgical results between the two groups were analyzed with regard to the preoperative and post-operative deviation angles and the postoperative drift. The postoperative deviation angle was measured on postoperative day 1 as well as at two weeks, three months, six months and the final visit after surgery. RESULTS: There were no statistically significant differences in the mean preoperative and postoperative deviation angles between the two groups. In 30 (88%) patients in the non-adjustable group and 15 (75%) patients in the adjustable group, postoperative deviation was less than 15 prism diopters (PD) at the three month follow-up. There was no significant difference in the mean postoperative drift between the two groups. CONCLUSIONS: Strabismus surgery with adjustable sutures did not show a significantly better result than surgery without adjustable sutures in the treatment of sensory exotropia. Considering the amount of postoperative exodrift in both groups, we postulate that the immediate ocular alignment after surgery for sensory exotropia should be orthophoric or 5-6 PD of esodeviation.

The Effect of an Intravitreal Triamcinolone Acetonide Injection for Acute Nonarteritic Anterior Ischemic Optic Neuropathy

The purpose of this case report is to evaluate the visual outcome of an intravitreal triamcinolone acetonide injection (IVTA) as a treatment for a patient with acute nonarteritic anterior ischemic optic neuropathy (NAION). A 65-year-old male patient with severe visual loss due to acute NAION was treated with 4 mg/0.1mL IVTA. Fundus examination and measurements of the patient's best-corrected visual acuity and visual field were performed before and after the injection at 2 weeks, 1 month, 3 months, and 6 months. The best-corrected visual acuity changed from 0.05 before the injection to 0.16 at 2 weeks, 0.3 at 1 month, and 0.4 at 3 months and at the final visit. Optic disc swelling had markedly decreased at 1 week postoperatively and disappeared at 2 weeks after the injection. The clinical course of this patient suggests that an IVTA may be effective in increasing visual acuity following an acute NAION. A large randomized controlled trial is needed to assess the efficacy of IVTA as a treatment for NAION.

The Effect of Unilateral Medial Rectus Muscle Resection in Patients with Recurrent Exotropia

PURPOSE: To investigate the effect of unilateral medial rectus muscle resection for recurrent exotropia after bilateral lateral rectus muscle recession for intermittent exotropia METHODS: A retrospective analysis was made of thirtypatients who underwent unilateral medial rectus resection for recurrent exotropia. All had prior bilateral lateral rectus recession for intermittent exotropia. Data were collected for age, the preoperative deviation, the postoperative deviation at 2 weeks, 3 months, 6 months and the last visit, and the amount of medial rectus resection performed. RESULTS: The average preoperative deviation was 27.0+/-3.6 PD. After unilateral medial rectus resection, average deviation at distance was 2.8 PD at postoperative 2 weeks, 4.5 PD at 3 months, 5.1 PD at 6 months and 5.8 PD at last visit. The average deviation corrected per millimeter of medial rectus resection was 3.53+/-0.17 PD/mm. CONCLUSIONS: Considering that deviation angles of recurrent exotropia is smaller than those of primary surgery and the possibility of saving the other medial rectus muscle, unilateral rectus muscle resection could be effective surgical method for recurrent exotropia.

Reduction of Deviation Angle During Occlusion Therapy: In Partially Accommodative Esotropia with Moderate Amblyopia

PURPOSE: To evaluate changes in ocular alignment in partially accommodative esotropic children age ranged from 3 to 8 years during occlusion therapy for amblyopia. METHODS: Angle measurements of twenty-two partially accommodative esotropic patients with moderate amblyopia were evaluated before and at 2 years after occlusion therapy. RESULTS: Mean deviation angle with glasses at the start of occlusion treatment was 19.45+/-5.97 PD and decreased to 12.14+/-12.96 PD at 2 years after occlusion therapy (p<0.01). After occlusion therapy, 9 (41%) cases were indications of surgery for residual deviation but if we had planned surgery before occlusion treatment, 18 (82%) of patients would have had surgery. There was a statistical relationship between increase of visual acuity ratio and decrease of deviation angle (r=-0.479, p=0.024). CONCLUSIONS: There was a significant reduction of deviation angle of partially accommodative esotropic patients at 2 years after occlusion therapy. Our results suggest that occlusion therapy has an influence on ocular alignment in partially accommodative esotropic patients with amblyopia.

Five-Year Follow-up Results of Refractive Accommodative Esotropia

PURPOSE: To evaluate the clinical characteristics of refractive accommodative esotropia followed up for 5 years. METHODS: Forty-three subjects with refractive accommodative esotropia, who had been followed up for at least 5 years were included in this study. Age and sex distribution, age at onset and the interval between onset of esotropia and initial visit were evaluated. Changes of the angle of deviation and the amount of hyperopia during follow-up period were analyzed. RESULTS: The initial amount of hyperopia of 4.42+/-3.27D was decreased to 3.84+/-3.46D by the last exam. The average rate of hyperopia decrease per year was 0.12 diopters. The average angles of deviation at the initial and final exam were 31.74+/-13.72PD and 30.11+/-14.27PD, respectively. Among the 43 subjects who participated in this study, decompensation occurred in 2 patients in the third year and 1 patient in the fourth year. CONCLUSIONS: There is a tendency for the amount of hyperopia to decrease over time. Further, deviation may deteriorate over time as well. Thus, long term follow-up management is necessary to control deviation in patients with refractive accommodative esotropia.

Change of Deviation Angle after Monocular Occlusion in Intermittent Exotropia

PURPOSE: To measure the amount of increased angle of strabismus at far and near distance after 1 hour of monocular occlusion in intermittent exotropia and to evaluate the surgical outcome. METHODS: Fifty-five patients operated on for intermittent exotropia from May 2002 to February 2003 and followed for at least 6 months postoperatively were prospectively studied. In all patients, the angle of deviation was measured at 6 m and 33 cm before and 1 hour after monocular occlusion. Patients with an increase of exodeviation less than 5PD after occlusion were defined as non-responders, and were operated for the pre-occlusion angle (Group 1). Patients with an increased angle more than 5PD after occlusion were defined as responders, and were operated according to the pre-occlusion (Group 2) or post-occlusion (Group 3) angle. RESULTS: Thirty (54.5%) of the 55 patients were responders of distant deviation with an increase of 6.20+/-2.96 PD after occlusion. Forty-three (78.2%) of the 55 patients were responders of near deviation with an increase of 13.4+/-7.12PD after occlusion. Group 3 who underwent surgery for the increased angle after occlusion had a higher frequency of satisfactory surgical outcome (71.4%) than group 1 (68.0%) and group 2 (62.5%). However, these differences were not statistically significant (P>0.05, Chi-square test). CONCLUSIONS: The angle of strabismus in patients with intermittent exotropia who undergo surgery should be measured at 1 hour after monocular occlusion to improve the surgical outcome.

The Effect of Unilateral Lateral Rectus Recession for the Treatment of Moderate-Angle Exotropia

PURPOSE: To evaluate the surgical results and the amount of correction per millimeter after unilateral lateral rectus recession for moderate-angle exotropia in a pediatric population. METHODS: This study included 30 subjects who underwent 9-mm unilateral lateral rectus recession for basic type intermittent exotropia with deviation of 23 to 28 prism diopters (PD) and were followed-up for 6 months or more after surgery. RESULTS: Seventeen subjects were male and 13 were female. The mean age of subjects was 9.7 years. Defining satisfactory postoperative ocular alignment as 8PD or less, 25 of 30 subjects (83.3%) were satisfactorily aligned at 2 months postoperatively. The success rates at 4, and 6 months postoperatively were 76.7% respectively. No overcorrected subjects were found after 2 months postoperatively. A postoperative limitation of abduction was not found in all subjects after 2 months postoperatively. The average amount of correction per millimeter of recession at 2, 4, and 6 months was 2.83+/-0.26PD, 2.75+/-0.37PD, and 2.72+/-0.44PD respectively (range, 1.56 to 3.18PD). There was no statistically significant difference in the amount of correction per millimeter throughout the follow-up period (ANOVA, p=0.05). CONCLUSIONS: Unilateral lateral rectus recession appears to be an effective surgical procedure for the treatment of moderate-angle exotropia. However to reduce the rate of undercorrection, which is one of disadvantages of this procedure, proper patient selection is required.

The Long-term Follow-up Results of Patients with Partially Accommodative Esotropia after Conventional Surgery

PURPOSE: To evaluate the changes of clinical features after long-term follow-up observation on patients with partially accommodative esotropia who had undergone conventional surgery. METHODS: Thirty-five patients who maintained orthophoria for at least one year duration after surgery were evaluated. The amount of surgery was measured based on the near angle of deviation after full hyperopic correction. The comparison was made based on the best corrected visual acuity, refractive errors, degree of stereopsis and ocular positions before and after surgery. RESULTS: The mean spherical equivalent was +4.46 D before surgery and +3.66 D at the final examination. Among a total of 70 eyes, the best corrected visual acuity of 0.6 or less was seen in 16 before surgery, and in 12 at the final examination. The average angle of deviation was 50.14 PD before correction and 34.43 PD after correction. The Titmus stereotest after surgery was 80 sec of arc in 6, and even 40 sec of arc in 2 out of the 35 patients. At the final examination, 29 of the 35 patients revealed stable orthophoria, but exophoria, in a range of 15-25 PD, developed in 6 patients. Of these 6, 4 had anisometropic amblyopia, and 1 had bilateral high hyperopia of 8.0 D with refractive amblyopia. CONCLUSIONS: Long-term follow-up observation is essential after surgery for partially accommodative esotropia due to fear of the gradual development of consecutive exotropia, particularly in amblyopia cases, even though acceptable initial postoperative orthophoria has been achieved.

The Differences of Visual Field Defects in Three Types of Primary Glaucoma

PURPOSE: To compare the characteristics of visual field defect in primary open-angle glaucoma (HTG), normal-tension glaucoma (NTG) and primary angle-closure glaucoma (ACG). METHODS: We investigated the visual field defect of HTG (n=75), NTG (n=58), ACG (n=150) patients from March 2000 to November 2002. We compared the severity and asymmetry of the visual field defect in both eyes, the asymmetry of a more severely affected hemifield between both eyes, and the frequency of an early visual field defect with equivalently affected superior and inferior hemifield. RESULTS: The visual field defect was the severest in HTG, and the mildest in ACG. Asymmetry in severity of visual field defect between both eyes was the severest in HTG, and the mildest in NTG. The asymmetry of the affected hemifield between both eyes in terms of superior and inferior hemifields was most frequent in NTG. The frequency of the early visual field defect with equivalently affected superior and inferior hemifields occured mostly in NTG. ACG without an attack history had a more severe visual field defect than that with an attack history. CONCLUSIONS: The topographical pattern of the visual field defect was different in HTG, NTG, and ACG. There may be different pathophysiological mechanisms in the three types of primary glaucoma.

Comparison of Clinical Features in Three Types of Primary Glaucoma

PURPOSE: To compare the clinical characteristics of primary open-angle glaucoma (HTG), normal-tension glaucoma (NTG) and primary angle-closure glaucoma (ACG) patients. METHODS: We investigated the clinical characteristics of HTG (n=75), NTG (n=58), and ACG (n=150) patients from March 2000 to November 2002. We compared the age at initial glaucoma diagnosis, sex, family history, systemic diseases, refractive errors, and corneal curvature among the three groups. RESULTS: HTG was younger than the others at initial glaucoma diagnosis. In ACG, the incidence rate was higher in women, but it was in HTG, higher in men. Family history of glaucoma was significantly more prevalent in HTG than in the others. NTG showed higher prevalence of cardiovascular disease and hypotension than the others. In refractive errors, there was statistically significant difference among the three groups and HTG had more severe myopia than the others. ACG had the steepest cornea curvature. CONCLUSIONS: Three types of primary glaucoma (HTG, NTG and ACG) differed somewhat in clinical feature. This finding will be helpful in the early diagnosis and treatment of glaucoma.

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.

The Influence of Monocular Occlusion on the Preoperative Ocular Alignment and the Surgical Outcome in Basic Intermittent Exotropia

PURPOSE: This study was to evaluate the influence of monocular occlusion on the preoperative ocular alignment and the surgical outcome of basic intermittent exotropia. METHODS: We examined 42 patients with basic intermittent exotropia who were operated and followed for at least 6 months postoperatively from January 2001 to August 2002. In all patients, angle of misalignment measured while the patients fixate on an accommodative target at 6m and 33cm, and after 2 hours of monocular occlusion. The subjects were divided into two groups: Gruop 1-far angle of misalignment did not increase after 2 hours of monocular occlusion, Group 2-far angle of misalignment increased in 3PD or more after 2 hours of monocular occlusion. Group 2 underwent surgery for the increased deviation of far angle. RESULTS: Among 42 patients with basic intermittent exotropia, Group 1 included 27 (64.3%) patients and Group 2 15 (35.7%) patients. In Group 2, the mean ( +/- SD) increase in the angle of exotropia after 2 hours of monocular occlusion was 5.33 ( +/- 2.74)PD. The success rate of surgery was 77.8% (21/27 patients) in Group 1, 93.3% (14/15 patients) in Group 2 at 6 months after surgery and 70.4% (19/27 patients), 93.3% (14/15 patients) at the final visit. There was no statistically significant difference (p> 0.05). CONCLUSIONS: This study showed the significant influence of monocular occlusion on the ocular misalignment before surgery and surgical outcome in basic intermittent exotropia. Angle of misalignment measured after 2 hours or more of monocular occlusion seemed to be meaningful.

The Effect of Transscleral Pressure on Human Scleral Thickness and Hydration

PURPOSE: The purpose of this study was to evaluate the effect of transscleral pressure on the thickness and hydration of the human sclera. METHODS: Scleral sections excised from moist-chamber-stored human globes were mounted in a perfusion chamber that can create transscleral pressure. The scleral thickness was measured at 15-minute intervals using ultrasonic pachymetry with pressure changes of 15, 30, and 60 mmHg every 2 hours. The scleral hydration was measured by maintaining a constant pressure (15, 30, and 60 mmHg) for 4 hours, weighing the hydrated tissue, then drying for 24 hours at 120degrees C, and finally weighing the dry tissue. RESULTS: The changes of scleral thickness from the initial control thickness in the 7-mm perfusion chamber (n=6) were -0.38+/-2.11%, 0.26+/-2.99 %, and -3.92+/-3.40% at 15, 30, and 60 mmHg, respectively. In the 10-mm perfusion chamber (n=5), the thickness changes were -0.56+/-1.35%, -1.05+/-1.63%, and -2.71+/-1.60% at 15, 30, and 60 mmHg, respectively. Scleral thickness was slightly decreased with the increase of transscleral pressure. There was a statistically significant decrease in scleral thickness from 30 mmHg to 60 mmHg in the 7-mm perfusion chamber (p0.10). CONCLUSIONS: The scleral hydration remained essentially unchanged with the transscleral pressure change of 0 ~ 60 mmHg, whereas the scleral thickness showed a slight decrease with the increase of transscleral pressure. Further histologic studies will be needed to assess the ultrastructural change of human sclera in the future.

Experimental Transscleral Ocular Drug Delivery: Use of Pluronic F-127 Gel and Fibrin Glue as a Sustained Release System

PURPOSE: The purpose of this study was to evaluate the effect of two sustained release systems (Pluronic F-127 gel and Fibrin glue) on the diffusion of dexamethasone across the human sclera. METHODS: Scleral sections excised from moist-chamber-stored human globes were mounted in a perfusion chamber that can create transscleral pressure. In the sustained release study, sample (100 muL) of 3H-dexamethasone in Pluronic F-127 gel or Fibrin glue was added to the episcleral side of the tissue, while BSS plusR was perfused across the uveal side at an transscleral pressure of 15 mmHg. Perfusate fractions were collected and measured using scintillation spectrometry and scleral permeability was calculated. RESULTS: The apparent permeability constants of the human sclera to 3H-dexamethasone in BSS plus(R) (the control value), Pluronic F-127 gel, and Fibrin glue were 1.15+/-0.11x10(-5) cm/s (n=5), 1.49+/-0.33x10-6 cm/s (n=5), and 7.32+/-0.98x10(-6) cm/s (n=7), respectively. The permeability values of Pluronic F-127 gel and Fibrin glue were relatively lower than the control value. Pluronic F-127 gel and Fibrin glue showed a uniform sustained release characteristic during a 24-hour period. The cumulative release rates of dexamethasone through the human sclera from BSS plus(R) (the control value), Pluronic F-127 gel, and Fibrin glue were 84.0+/-1.5% (n=5), 29.3+/-5.8% (n=5), and 61.5+/-5.9% (n=4) at 20 hours, respectively. There were significant differences in the human scleral permeability constants and cumulative release rates among the three vehicles (p<0.0001). CONCLUSIONS: Pluronic F-127 gel and Fibrin glue provided a slow, uniform sustained release during a 24- hour period. This study established a strong possibility of the new transscleral drug delivery in vitro using the sustained release systems of Pluronic F-127 gel and Fibrin glue. This may be a good experimental tool in the future development of a practical drug delivery system across the sclera for the treatment of a variety of chorioretinal disorders.

Occlusion Effects on Anisometropic Amblyopia

PURPOSE: To evaluate the effects of occlusion therapy on anisometropic amblyopia and investigate the factors that influence on the final vision. METHODS: Fifty two patients with anisometropic amblyopia, whose age ranged from 3 to 12 years, were treated with full and partial occlusion therapy. RESULTS: The degree of anisometropia was 3.23+/-1.99 D in hyperopia group and 2.00+/-0.98 D in myopia group. The best corrected visual acuity and final vision were 0.29+/-0.14 and 0.52+/-0.22 in hyperopia group, while 0.34+/-0.16 and 0.63+/-0.16 in myopia group. But statistically significant difference was not found between two groups. The best corrected visual acuity was significantly correlated with the degree of anisometropia. The final vision was also significantly correlated with the degree of anisometropia. As expected, the final visual acuity was strongly correlated with the best corrected visual acuity. But no statistically differences were found based on the age of initial treatment and sexual difference. CONCLUSIONS: The severity of amblyopia and the effect of occlusion therapy were more correlated with the degree of anisometropia than the age of initial treatment and the type of anisometropia.

Clinical Study of Anisometropia

No Abstract Available.

Distribution of the Axis of Astigmatism According to Age in Children

We performed this study to investigate the distribution of axes of astigmatism, the occurrence and amount of astigma- tism among pediatric population aged from 1 to 15 years who have visited our clinic from January to December 1997. After routine ophthalmologic examination to rule out any organic abnormality, the cycloplegic refraction was performed with 0.5-1.0% atropine on 529 eyes. Out of 529 eyes, astigmatism was found in 356 eyes (67.3%) with the highest incidence in 15-year-old group being 87.0%. Among 356 eyes with astigma- tism, with-the-rule astigmatism was found in 322 eyes (90.4%); against-the-rule, 30 eyes (8.5%); oblique, 4 eyes (1.1%). With-the-rule astigmatism occurred far more frequently found than against-the-rule in all age groups. As to the type of astigmatism classified by the state of refractive errors,hyperopic astigmatism was found in 144 eyes (40.4%); myopic,136 eyes (38.3%); mixed, 76 eyes (21.3%). Of the total of 356 eyes with astigmatism, astigmatism of 1.0 diopter or less was found in 181 eyes (50.8%).

Positional Changes of Reattachment Site after Superior Rectus Recession in Rabbit

In determining the effects of strabismus surgery, it is very important to know where the reattachment site of an extraocular muscle following recession procedure is located. Undercorrections or overcorrections after muscle surgery have been thought to be due to a postoperative positional changes of reattachment site along the surface of the globe. The author performed this experimental study to evaluate the amounts of changes of reattachment site after recession procedure in rabbit with 4 different methods of scleral fixation;direct suture with 6-0 vicryl, hang-back suture, application with Tisseel and Histoacryl. Superior rectus recession was performed in all 40 rabbit eyes, 10 eyes in each group. The distance from limbus to proximal end of recessed superior rectus muscle was measured on day 1, 2, 3, 5 and 7 postoperatively. Further measurements were followed at 2, 3, 4 and 8 weeks after recession procedure. The muscles were found an average of 0.4mm posterior to the intended position in direct suture group and 0.5 mmin hang-back suture group at one week postoperatively. But in the other two groups in which tissue adhesive agents, Tisseel and Histoacryl were used, the amount of displacement of the reattachment site were minimal of within 0.1 mm. From this experimental study, it is suggested that the positional changes of the reattachment site after recession procedure may influence the surgical corrective effects for strabismus.