Horizontal and vertical angle kappa

BACKGROUND

The aim of this study is to report the geometric range of angle kappa formation in patients with and without strabismus.

PATIENTS AND METHODS

This is a retrospective study of three patients with angle kappa in different planes. Routine eye examinations, including visual acuity, slit-lamp examination, and ophthalmoscopy, were performed. A thorough orthoptic examination revealed a notable difference between the prism and alternate-cover test and the Hirschberg measurements.

RESULTS

The first patient exhibited a bilateral vertical angle kappa into opposite directions due to retinochoroidal scars. Two other patients presented with horizontal angle kappa deviations. In one patient a true accommodative esotropia was exaggerated by a right negative angle kappa. The other patient had a pseudoexotropia due to bilateral positive angle kappa. Macular ectopia was noted in all cases.

CONCLUSIONS

The patients herein reported demonstrate a marked variability of angle kappa occurrence in the horizontal and vertical plane. The angle kappa can exaggerate or conceal the size of the true heterotropia.

Unilateral recession and resection in Duane syndrome

PURPOSE

To assess the efficacy of lateral rectus resection with medial rectus recession in the affected eye of patients with Duane retraction syndrome (DRS) with esotropia and limited abduction, compared with bilateral medial rectus recessions.

METHODS

The charts of 9 patients with DRS who underwent a recession-resection procedure and 10 patients with DRS who underwent bilateral medial rectus recessions were reviewed. Ocular ductions (graded from 0 = full duction to -4 = total deficit), severity of retraction, alignment, head position, and binocular single vision field (for study group only) were recorded before and after surgery.

RESULTS

Before surgery, the study and control groups did not differ in mean primary position esotropia (16.9 and 18.8 PD, respectively), face turn (16.5 degrees and 15.0 degrees, respectively), average limitation of abduction (-3.9 and -3.7, respectively), or adduction (-0.1 and -0.3, respectively). After surgery, both groups had similar mean face turns (3.9 degrees and 1.0 degrees ), esotropia (3.3 PD and 1.0 PD), and abduction limitation in the affected eye (-2.4 and -2.6). However, mean adduction was significantly worse in the control group than in the study group (-1.5 vs -0.6, P = .02). Globe retraction improved in all control subjects. It worsened in 5 study subjects and did not improve in the other 4. In the study group, 1 patient required reoperation for undercorrection and another was overcorrected.

CONCLUSION

Seven of 9 patients with DRS, selected on the basis of esotropia, limited abduction, and mild retraction, benefited from a recession-resection procedure. Abduction improved to the same degree as seen after bilateral medial rectus recessions, with less tendency to limit adduction.

Outcome of inferior oblique recession with or without vertical rectus recession for unilateral superior oblique paresis

PURPOSE

To determine the effectiveness of a standard fixed 10 mm inferior oblique (IO) recession with or without vertical rectus recession in visually mature patients with unilateral superior oblique paresis (SOP) and mild to moderate IO overaction.

METHODS

The records of 24 patients over 12 years of age who had 10 mm IO recession for SOP, for IO overaction of +1 to +3 (out of maximum +4), with 6+ months of followup were reviewed. Criteria required for a "successful" outcome included: 1. hyperdeviation of 5delta or less in primary position; 2. elimination of any compensatory abnormal head posture; and 3. elimination of diplopia in the central 30 degrees of the binocular visual field.

RESULTS

In 16 cases of IO recession alone, 88% were "successful" and in 8 cases who had in addition either contralateral inferior rectus recession or ipsilateral superior rectus recession, 75% were "successful". IO 10 mm recession alone led to an average reduction of 9.1 PD of hypertropia in primary position.

CONCLUSION

A standard ungraded 10 mm recession of the IO alone or in combination with vertical rectus muscle recession is an effective weakening procedure with a high success rate for patients with unilateral SOP with mild to moderate IO overaction. In occasional cases of undercorrection, a subsequent IO myectomy is very feasible and effective.

The double-bellied inferior oblique muscle: clinical correlates

PURPOSE

We previously reported an 8% incidence of double-bellied inferior oblique (IO) muscles at the surgical capture site (10-12 mm from insertion) in cadaveric specimens. This companion study sought to determine how often this anomaly is encountered at surgery for clinically overacting IO muscles and whether clinical findings or surgical outcomes in cases with double-bellied muscles differ from those with single-bellied muscles.

METHODS

For 7 years we collected preoperative, intraoperative, and postoperative data on all patients for whom one surgeon performed primary IO weakening operations for overactions. We compared eyes with double-bellied IO muscles to those with single-bellied muscles on 4 variables--gradings of preoperative IO and superior oblique (SO) actions, presence of fundus excyclotropia, differences between horizontal deviations in upgaze and downgaze, and presence and sizes of primary position hypertropias--to determine whether one or more of them could predict the presence of a double-bellied muscle. Finally, we assessed postoperative IO actions to determine whether the presence of a double-bellied muscle influenced the effectiveness of IO weakening surgery in reducing overaction.

RESULTS

Among 162 patients (247 eyes) who underwent this surgery, 77 (77 eyes) had unilateral surgery and 85 (170 eyes) bilateral. Twenty-seven (10.9%) of the 247 muscles had double bellies. Among all variables compared, only the incidence of fundus excyclotropia differed significantly between groups, occurring more often in eyes with double-bellied IO muscles (48% vs 27%; P =.041). The efficacy of weakening surgery in reducing overactions was similar in both groups.

CONCLUSION

The finding that eyes with double-bellied IO muscles showed a higher incidence of fundus excyclotropia suggests that the presence of a second belly may alter the physiologic action of the IO muscle.

A prospective evaluation of anterior transposition of the inferior oblique muscle, with and without resection, in the treatment of dissociated vertical deviation

BACKGROUND

Anterior transposition of the inferior oblique muscle (ATIO) has become a popular surgical treatment for dissociated vertical deviation (DVD), particularly in patients with coexisting inferior oblique muscle overaction (IOOA). We wanted to assess whether adding a resection improves the outcome compared with standard anteriorization.

METHODS

We undertook a prospective, randomized evaluation of ATIO, with and without a 7-mm resection, in patients with DVD of at least 5 PD in one eye. We included 51 eyes of 30 patients, 26 eyes treated with the standard ATIO and 25 treated with a 7-mm resection added. We recorded the size of the preoperative and final DVD, grade of the preoperative and final IOOA, rates of reoperation, and complications. Mean follow-up was 15.4 months in the standard group and 25.0 months in the resection group, with a minimum of 4 months for all cases.

RESULTS

The median preoperative and postoperative DVD was 12 PD and 4 PD in the standard group, respectively. This compared with 14 PD and 4 PD, respectively, in the resection group, representing no statistically significant difference in outcome. The presence or absence of IOOA did not influence the result of ATIO for either group. No significant complications of surgery occurred in either group.

CONCLUSIONS

ATIO is an effective treatment for DVD and can be used to treat DVD in patients with or without IOOA, with few adverse effects. Our study revealed no advantage to adding a 7-mm resection to the standard procedure.

Strabismus examination by telemedicine

OBJECTIVE

To evaluate the reliability of strabismus assessment using telemedicine (TM) technology.

DESIGN

Two prospective interobserver agreement studies. One study compared the agreement between a standard and a TM examination, whereas the other assessed agreement between two independent standard examinations.

PARTICIPANTS

Strabismus patients over 4 years of age examined at a remote community clinic and patients assessed in a strabismologist's urban practice.

METHODS

Forty-two patients were examined in person by a pediatric ophthalmologist at the remote community and independently by a pediatric ophthalmology fellow by means of TM (TM-standard study). The TM examination was performed with the help of a qualified ophthalmic assistant at the remote telecommunication center using a Power Cam 100 camera, a Picture Tel Concorde 4500 teleconferencing system, and a 224 kilobyte bandwidth. For comparison, independent in person examinations were performed on 43 patients by both examiners (standard-standard study). Agreement was measured using unweighted kappa (k) for categorical data, the intraclass correlation coefficient (ICC) for continuous data, and percent agreement. The odds of disagreement with TM (comparing the TM-standard versus standard-standard studies) was assessed with logistic regression analysis.

MAIN OUTCOME MEASURES

Three parameters were assessed: (1) category of strabismus, determined by observation without cover test; (2) angle of deviation at 0.33 and 6.0 m; and (3) ocular muscle action.

RESULTS

Agreement on the category of strabismus was good (k > 0.61) other than for vertical deviations. However, there was good to excellent agreement between TM and standard examinations on the vertical (ICC = 0.78) and horizontal (ICC = 0.79) angles of deviation with 6-m fixation with the cover test. Muscle ratings agreed within one point for the lateral, superior, and inferior rectus muscle actions in more than 90% of the eyes examined. Although good agreement was observed in the TM-standard study, it was inferior to the agreement in the standard-standard study. Examination by TM increased the odds of disagreement compared with examination in person by twofold to threefold.

CONCLUSIONS

Strabismus examination can be performed with a good level of reliability with the use of medium bandwidth video teleconferencing equipment. However, reduced reliability has been noted in the detection of small vertical deviations by inspection and in evaluating oblique muscle actions.

Bilateral idiopathic Brown's syndrome with delayed onset in the second eye

PURPOSE

We describe 6 cases of a previously unreported variation of bilateral Brown's syndrome that presented in congenital form in one eye and developed later in the fellow eye with no underlying cause.

METHODS

We reviewed the clinical records of 6 patients from 6 separate practices to determine whether there were any common clinical features on presentation or in their clinical courses.

RESULTS

All 6 patients were diagnosed with unilateral congenital Brown's syndrome at the first ophthalmologic assessment but showed no evidence of the syndrome in the fellow eye. In 5 cases the contralateral syndrome developed in the second eye after surgery was performed on the first eye, and in 1 case it developed before any surgery was done. The ages at onset of the syndrome in the second eye ranged from 2 to 8 years. None of the children had any evidence of systemic illness or local orbital disease to explain an acquired Brown's syndrome.

CONCLUSION

To our knowledge, this is the first reported series of cases of bilateral Brown's syndrome that manifested sequentially in the eyes with no known causes for an acquired syndrome in the second eye. This finding supports the premise that congenital and acquired Brown's syndrome are on a continuum with a common pathophysiology of restriction of free movement of the superior oblique tendon in the trochlea.

Anatomic variations of the inferior oblique muscle: a potential cause of failed inferior oblique weakening surgery

PURPOSE

To document the variations in normal anatomy that occur at the insertion of the inferior oblique muscle and in the vicinity of its surgical capture site (10 to 12 mm from the insertion).

METHODS

One hundred intact cadaver orbits with no history of eye muscle or orbital disorders during life were carefully dissected to expose the entire length of the inferior oblique muscle. The number of divisions of muscle at the insertion, total width of the muscle belly, and variations in anatomy 10 and 12 mm from the insertion were recorded.

RESULTS

Seventeen (17%) of the 100 inferior oblique muscles had multiple divisions at the insertion. Eight muscles (8%) had two bellies at 10 or 12 mm from the insertion. Among these eight, four had two distinct (bifid) bellies extending to the insertion, and four had dehiscences in the muscle. The mean muscle width among these eight specimens was 0.5 and 0.7 mm larger than the mean width of the other 92 specimens at the 10 mm and 12 mm positions, respectively. Neither difference was significant at the .05 level.

CONCLUSIONS

Multiple insertions were found in 17% of inferior oblique muscles examined; duplications of the inferior oblique muscle at the surgical capture site were found in 8%. These duplications may account for some cases of recurrence or persistence of inferior oblique overaction after weakening surgery, owing to inadvertent incomplete capture of the muscle during surgery.

Monocular horizontal OKN in observers with early- and late-onset strabismus

Several reports on monocular optokinetic nystagmus (OKN) in observers with strabismus have found that asymmetry of OKN tends to occur in both eyes of observers with an early onset of strabismus but only in the deviating eye of those with a later onset of strabismus. Our objective was to quantify and compare the magnitude of the OKN asymmetry in each eye as a function of observer's age at onset of strabismus. We studied monocular OKN in ten observers with early-onset (up to 24 months of age), seven observers with late-onset (after 24 months of age) unilateral strabismus, and 12 normally sighted control observers. In the deviating eye, observers with early-onset strabismus showed large OKN asymmetries in favour of nasalward motion while observers with late-onset strabismus showed smaller OKN asymmetries in that eye. The majority of early- and late-onset observers showed near normal OKN in the non-deviating eye although the early-onset observers showed bilateral asymmetries more often. These findings may be due to both age at onset of strabismus and chronological age and are discussed in terms of the issue of plasticity or recovery of function.

Electrophysiological evidence of cortical fusion in children with early-onset esotropia

PURPOSE

To investigate sensory fusion responses in infants and children with early-onset esotropia to gain insights into the sequence of events that leads to strabismus.

METHODS

Sensory fusion was tested by measuring visual evoked potential (VEP) responses to dynamic random dot correlograms (DRDCs) in a group of children (n = 23) with early-onset esotropia. Thirteen children were tested before surgical alignment, and 13 children were tested after surgical alignment (three children were tested before and after surgery). If the angle of strabismus was larger than 5 prism diopters, it was corrected with Fresnel prisms (Fresnel Prism and Lens, Scottsdale, AZ).

RESULTS

Five (38%) of the 13 children who were tested before surgery showed detectable VEP responses to correlogram stimuli compared with 11 (85%) of the 13 children who were tested after surgical alignment. There were no significant statistical differences between VEP responses to DRDCs from the postsurgery group and VEP responses from an age-matched control group with normal binocular vision.

CONCLUSIONS

The presence of cortical sensory fusion in children with early-onset esotropia suggests that a congenital defect of sensory fusion cannot be the root cause of esotropia in most children. The data suggest that sensory fusion, when measured by VEP responses to DRDCs, is more robust than stereopsis to abnormal binocular experience and support the notion that pathways processing correlated/anticorrelated stimuli may not completely overlap with pathways processing disparity information.

Vertical latent nystagmus component and vertical saccadic asymmetries in subjects with dissociated vertical deviation

PURPOSE

This study was conducted to quantify the vertical component of a latent nystagmus observed in subjects with dissociated vertical deviation (DVD), as well as to provide further evidence for vertical saccadic asymmetries in these individuals.

METHODS

Binocular eye movements of subjects with DVD were recorded in two dimensions using a noninvasive video-based eye tracker while cover/uncover tests, alternate cover tests, and vertical saccades were performed.

RESULTS

A small amplitude (1.5 degrees or less) vertical component of latent nystagmus can be observed in some subjects with DVD and is larger in the deviating eye than in the viewing eye. The frequency of the vertical nystagmus component is the same in each eye for any given fixation condition but may change depending on which eye is fixating. DVD in the presence of a vertical component of latent nystagmus can be adequately modeled by the algebraic sum of an exponentially decreasing velocity DVD and a nystagmus with an exponentially decreasing slow phase velocity. In general, the occluded eyes of DVD subjects make smaller downward saccades than the viewing eyes.

CONCLUSIONS

It is possible but not obligatory that DVD subjects will have a vertical component of latent nystagmus. Algebraic summation of an exponentially decreasing velocity DVD and a vertical component of latent nystagmus provides a more parsimonious explanation of the observed saccadic eye movements than modeling the DVD itself as a combination of vergence and saccadic movements. Subjects with DVD show a range of saccadic yoking from nearly complete saccadic conjugacy to nearly complete dissociation.

Cortical binocularity and monocular optokinetic asymmetry in early-onset esotropia

PURPOSE

To investigate the correlation between directional asymmetry in ocular responses to monocularly viewed optokinetic stimuli (monocular optokinetic nystagmus, MOKN) and sensory fusion in infants and toddlers with early-onset esotropia.

METHODS

Subjects were 14 infants and toddlers with early-onset esotropia (7-26 months old; median, 10 months), and 16 with no esotropia (6-22 months; median, 11 months) who provided control data. Monocular optokinetic nystagmus in response to a 30 degrees/sec square-wave grating (0.25 cycles/degree) was measured by electro-oculogram. Sensory fusion was assessed with visual evoked potentials (VEPs) to random-dot correlograms after correction of the strabismus angle with Fresnel prisms.

RESULTS

All subjects with early-onset esotropia had MOKN with a faster slow-phase component for temporal-to-nasalward (TN) than nasal-to-temporalward (NT) motion. Ninety-three percent of subjects had MOKN asymmetry higher than the 95th percentile of the control group. Of subjects who cooperated with VEP fusion testing, 5 subjects with early-onset esotropia (45%) and 11 control subjects (92%) showed evidence of sensory fusion.

CONCLUSIONS

Symmetrical MOKN did not develop in infants and toddlers with early-onset esotropia. This deficit existed in most infants who showed sensory- cortical fusion. These results are consistent with the belief that optokinetic nystagmus asymmetry may not be associated with a deficit in the cortical fusion facility, but rather with deficits in binocular pathways projecting to MOKN control centers. These deficits may be associated with abnormal processing subsequent to sensory fusion or with abnormal processing in motion pathways, which run parallel to sensory fusion pathways.

Outcome criteria in strabismus surgery

Criteria for success in strabismus surgery should include more than just the alignment result in primary position. It is important to consider as well the extent of the field of BSV gained: restoring a useful range of BSV will maximize the patient's ability to carry on daily activities. Psychometric tests can also be used to provide objective measures of improvement following strabismus surgery. Irrespective of the patient's age, the realigning of an eye is reconstructive, not cosmetic, surgery. Surgery in children and adults can restore fusion and normalize the field of BSV in most cases. These gains are possible even in the presence of amblyopia. It could be argued that realigning a blind eye yields no functional improvement and should not necessarily be covered by insurance plans. These cases are not common. In all other cases the functional benefits of adult strabismus surgery justify maintaining insurance coverage for this surgery in jurisdictions throughout North America.

Registered eye position: short- and long-term effects of botulinum toxin injected into eye muscle

Botulinum toxin is sometimes injected into human eye muscles as an alternative to surgery in the correction of strabismus. Within minutes of botulinum injections into ungulate eye muscles, proprioceptive discharge from muscle spindles decreases dramatically. It is only over 7-48 h, however, that surgically treated strabismus patients usually show an altered proprioceptive signal about eye position, presumably from the palisade endings attached to the global multiply innervated fibers. How quickly will botulinum toxin alter proprioceptive registration of eye position in humans? First, to examine the short-term effects, we measured open-loop pointing responses (which requires knowledge of eye position) in six strabismus patients preinjection and then over a 45 min postinjection period, and in six normal controls over the same time period. Second, to examine the long-term effects, 13 strabismus patients were tested preinjection and then daily over the next 3 weeks, and three normal controls over the same time period. We compared their open-loop pointing responses with the injected eye fixating the target to the photographically determined position of the occluded other eye (a measure of where the patient would point if eye position were determined by efference, not proprioception). There were three groups of patients: esotropes with no previous injection, exotropes with no previous injection, and exotropes with previous injection. First, all patients showed significant correction of their tropias. Second, over the short-term, there was no difference in pointing responses found between the patients and the controls (t(18) = -1.427, P = 0.1706). Third, over the long-term, however, the difference between the pointing responses and eye position information was compared among the four groups across four posttests and a significant difference found (F3,12 = 58.988, P < 0.00001). Only in patients with no previous injections was there altered proprioceptive feedback about eye position. Also, injections into the medial rectus induced a significantly greater proprioceptive response than those injected into the lateral rectus. In humans, botulinum toxin alters proprioception from eye muscles only over the long-term. We suggest that the toxin temporarily affects proprioceptive feedback from palisade endings.

Screening for childhood strabismus by primary care physicians

OBJECTIVE

To review the clinical classification of strabismus, to describe the timing and method of strabismus screening examinations, and to discuss the principles of treatment.

QUALITY OF EVIDENCE

Current literature (1983 to 1995) was searched via MEDLINE using the MeSH headings strabismus, ocular motility disorders, and amblyopia. Articles were selected based on their date of publication, clinical relevance, and availability. Preference was given to more recent articles, articles with large numbers of subjects, and well-designed cohort studies. Official recommendations from academic groups were analyzed. Descriptions of clinical tests and their illustrations are based on classic texts.

MAIN FINDINGS

Primary care physicians should screen all low-risk children. High-risk children (low birth weight, family history of strabismus, congenital ocular abnormality, or systemic conditions with vision-threatening ocular manifestations) should be referred to an ophthalmologist for screening. Screening should be performed in the neonatal period, at 6 months, and at 3 years (Grade A recommendation), as well as at 5 to 6 years (Grade B recommendation). Screening examination includes inspection, examining visual acuity, determining pupillary reactions, checking ocular alignment, testing eye movements, and ophthalmoscopy.

CONCLUSIONS

Primary care physicians are essential to early detection of strabismus and amblyopia. Early detection can help minimize visual dysfunction, allow for normal development of binocular vision and depth perception, and prevent psychosocial dysfunction.

Postoperative drifts after adjustable-suture strabismus surgery

OBJECTIVE

To determine the drift patterns and success rates of adjustable-suture horizontal strabismus surgery when patients are aligned to predetermined target angles.

DESIGN

Case series.

SETTING

University-affiliated tertiary care hospital in Toronto; clinic and office care.

PATIENTS

A total of 109 patients aged 15 to 72 years who underwent adjustablesuture strabismus surgery (primary procedure or reoperation) for esotropia or exotropia performed by one surgeon between 1990 and 1994 who were followed for at least 6 months. Their final postoperative angles were in the target ranges of under 4 prism dioptres (PD) for esotropia surgery and 3 PD to 7 PD of esotropia for exotropia surgery.

OUTCOME MEASURES

Primary-position alignment before surgery, immediately after surgery or after adjustment of sutures, if needed (final alignment), and at 1 to 2 weeks, 6 to 8 weeks and 6 to 8 months after surgery; size and direction of drift from final alignment after surgery at 6 to 8 months; and rate at 6 to 8 months of reduction of strabismus angle to less than 10 PD.

RESULTS

Of the 109 patients 44 had esotropia (17 primary repair [group 1] and 27 reoperation [group 2]) and 65 had exotropia (29 primary repair [group 3] and 36 reoperation [group 4]). Overall, 48 patients (44.0%) required postoperative suture adjustment. The mean drifts from the final postoperative alignments were 1 PD for groups 1 and 2, 7 PD for group 3 and 3 PD for group 4, all in the exotropic direction. The corresponding surgical success rates were 82.4%, 92.6%, 93.1% and 94.4%. Over 6 to 8 months both esotropia groups had approximately equal tendencies to drift in either direction. Both exotropia groups showed almost equal tendencies to drift in either direction away from the mean exotropic shift for the group.

CONCLUSIONS

Because of our target alignments, our success rates at 6 to 8 months were high, for both primary surgery and reoperation. In all four patient groups the drift tendencies were symmetric about the mean.

Aplasia of the inferior rectus muscle. A case report and review of the literature

PURPOSE

The authors describe the clinical findings, results of preoperative radiologic studies, and results of surgery in a boy with congenital unilateral inferior rectus aplasia.

METHODS

A 2-year-old boy is described who presented with a significant anomalous head posture, a large incomitant vertical deviation with marked deficit of depression of the left eye, and positive head-tilt test results. Preoperative magnetic resonance imaging (MRI) defined an absent inferior rectus muscle; computed tomography showed no evidence of a craniofacial syndrome. Full tendon inferior transposition of the horizontal rectus muscles was carried out on the affected eye.

RESULTS

The compensatory head position was eliminated. The infraduction improved. The patient had a small left hypotropia after the healing phase.

CONCLUSIONS

To the authors' knowledge, this case is the first that used MRI to confirm preoperatively the isolated absence of an inferior rectus muscle. The MRI allowed effective surgical planning to correct the congenital abnormality.

Dissociated vertical deviation: head and body orientation affect the amplitude and velocity of the vertical drift

PURPOSE

Five subjects with dissociated vertical deviation (DVD) were studied to determine if the amplitude or velocity of the vertical components of the DVD were affected by head/body orientation with respect to gravity.

METHODS

Deviations were measured in head upright, head supine, and supine positions, with head hanging postures using a binocular CCD video-based infrared eye tracker. Subjects were required to fixate a target presented in the primary position during alternate or cover/uncover tests.

RESULTS

Amplitude and velocity of DVD both in onset and recovery were affected by head/body orientation with respect to gravity. In four of five subjects, the amplitude of the DVD was asymmetric between the two eyes when the head was upright. When the head/body was moved from an upright to a supine with head hanging backward condition, the amplitude of the DVD in the two eyes inverted. The eye with the larger DVD in the upright position had a smaller DVD in the head-hanging orientation. A similar relationship existed between velocity and head/body orientation. We found that DVD velocity increased with amplitude.

CONCLUSIONS

Passive effects of gravity on the eye-inorbit do not influence DVD magnitude or frequency of occurrence. The data suggest, however, that otolithic and possibly neck afferent inputs play a role in DVD magnitude and may be a part of the etiology of the condition.

Long-term changes in duration of relief with botulinum toxin treatment of essential blepharospasm and hemifacial spasm

PURPOSE

To determine long-term changes in duration of relief with serial treatments of botulinum A toxin (BAT) used to treat benign essential blepharospasm and hemifacial spasm, in view of conflicting reports as to whether BAT has an increasing, decreasing, or an unchanging duration of effect over a long period of treatment.

METHODS

Thirty-two patients with facial dyskinesia (20 with essential blepharospasm, 12 with hemifacial spasm) were followed between 5 and 9 years through a mean of 18 (range, 12-32) BAT treatments with prospective documentation of intervals of relief from symptoms. Repeated measures and linear regression analyses were used to determine trends in each group.

RESULTS

Marked inter- and intrapatient variability was found in the length of effect of BAT. Statistical analysis showed no significant changes in mean duration of relief within each group (P = 0.65 for essential blepharospasm, 0.36 for hemifacial spasm). There was a trend to slow decline in the interval of relief, especially in patients with an initial duration of effect greater than 150 days. No relation was found between duration of relief and age or sex of patient or grade and duration of disease before initial treatment.

CONCLUSION

In the long term, the mean duration of relief from symptoms with BAT changes little over a period of serial treatments. Short-term fluctuations in the length of therapeutic effect did not indicate the development of a resistance to treatment.

Unilateral surgery for exotropia with convergence weakness

We prospectively studied 14 patients whom we treated surgically for exotropia (XT) with convergence weakness measuring at least 8 delta for distance (6 m) that increased at least 8 delta at near (1/3 m). Surgery involved lateral rectus recessions and medial rectus strengthenings (advancements or resections) to eliminate distance and near deviations and simultaneously collapse near-distance differences. The medial rectus was strengthened more than the lateral rectus was recessed; amounts were based on the near deviation. Minimum follow-up was 6 months after surgery. Preoperatively, the mean XT at distance was 18.3 delta (range, 8 to 35 delta) and at near 30.1 delta (range, 16 to 50 delta). At latest follow-up evaluations the mean distance deviation was 0.1 delta XT and at near 1.8 delta XT. The near-distance differences were reduced by a mean of 10.2 delta; the mean postoperative difference was 1.7 delta. Unilateral surgery for XT with convergence weakness biased to medial rectus strengthening and geared to near deviation can successfully collapse the near-distance differences while satisfactorily aligning both distance and near fixation. This surgery has low risk of creating long-term postoperative esodeviations at distance.

A case of unilateral congenitally enlarged extraocular muscles

BACKGROUND

Enlargement of extraocular muscles is an uncommon finding in children. Little has been written in the literature about possible causes.

METHODS

The authors present the clinical findings of a young girl who had unilateral congenitally enlarged extraocular muscles at 8 months of age. She underwent computed tomography (CT) and magnetic resonance imaging (MRI) scans, systemic assessment, and extraocular muscle biopsy to determine a cause for the enlarged muscles.

RESULTS

The patient had a unilateral left esotropia and hypotropia at birth that was nonprogressive. High-resolution CT and MRI scans showed enlargement of the left inferior rectus, lateral rectus, and medial rectus muscles. Strabismus surgery undertaken at 2 years of age showed that the affected muscles were restricted on forced duction testing but were macroscopically normal in appearance. A biopsy specimen of the left lateral rectus muscle was processed for histologic, histochemical, and electron microscopic studies, but no abnormal pathologic findings were found.

CONCLUSION

This patient's constellation of findings appears to be unique: it does not follow any previously reported pattern of disorders of extraocular muscle enlargement.

Cyclotorsion in unilateral and bilateral superior oblique paresis

We studied excyclotorsion prospectively in 12 non-strabismic normal patients, 24 patients with unilateral superior oblique paresis (SOP), and 14 patients with bilateral SOP to determine which test and position, and what amount of torsion best discriminates between bilateral and unilateral SOP. For each patient, we measured torsion at near in primary position and in 20 degrees downgaze, using both the double Maddox rod (DMR) and Bagolini lens (BL) tests. We calculated the average of three measurements for each test in each position and the differences in mean excyclotorsion between downgaze and primary position for each patient for each test. To discriminate between unilateral SOP and normal, and bilateral and unilateral SOP patients, the best test and position combination was the DMR in downgaze (P = .0001). The probability of a torsion measurement indicating a unilateral SOP rather than a normal value was 95% at 6 degrees of excyclotorsion; of bilateral rather than unilateral SOP, 90% at 20 degrees. The range in the three torsion readings within patients with either DMR or BL in either position varied up to 7 degrees.

Egocenter location in children with strabismus: in the median plane and unchanged by surgery

PURPOSE

Previous studies have shown that there are spatial localization shifts after horizontal strabismus surgery when a patient performs an open-loop pointing task. After monocular enucleation, an adult will also show a shift in the pointing response. Other studies have shown that in children who underwent enucleation, the egocenter location shifts toward the remaining eye. Is the pointing shift after surgery in children with strabismus the result of a shift in egocenter location?

METHODS

Using a modified Roelofs' method for measuring the egocenter, eight children were tested before and after horizontal strabismus surgery to see if there were any shifts in egocenter location. One control group consisted of six children undergoing surgery for correction of vertical strabismus in which the horizontal muscles would be unaltered.

RESULTS

Presurgery measurements of egocenter location in the people with strabismus were the same as those found in the other control group of 12 normal children. Postsurgical measurements of eye position showed horizontal rotations of 14.5 degrees for the horizontal group and 2.4 degrees for the vertical group. Egocenter measurements showed no postoperative shift for either strabismus group.

CONCLUSIONS

Thus, the pointing shift seen in the previous studies is not from a shifting egocenter location but from a change in the registered position of the eye in the orbit.

Crowding and contrast in amblyopia

The crowding effect, defined as the ratio of visual acuities for letters presented in Snellen (i.e., line) format and isolated-letter format, was measured in the amblyopic eyes of 15 children and 15 adults with unilateral amblyopia. Normal limits were based on data from 20 children and 20 adults with no history of amblyopia. The crowding effect was compared for letters of high (96%) contrast and for letters of low (11%) contrast. We report that amblyopia can differentially affect line and isolated-letter acuity for both high- and low-contrast letters. For the patients that show an abnormal crowding effect, this effect can be: (1) significantly stronger, (2) significantly weaker, or (3) not significantly different for high- than for low-contrast letters. These findings are consistent with the hypothesis that the crowding effect is contrast-dependent in some amblyopic eyes of both child and adult unilateral amblyopes.

Method for identifying amblyopes whose reduced line acuity is caused by defective selection and/or control of gaze

Three visual tests were administered to a group of 15 amblyopic children, 15 adult amblyopes and two age-matched control groups, each of 20 subjects. Test results comprised visual acuity for recognizing high contrast letters presented in line (i.e. Snellen) format, isolated-letter format and repeat-letter format. The classical Snellen format confounds the effects of gaze control defects with the effects of adjacent contours on a patient's ability to recognize a foveated letter. We designed a repeat-letter format intended to unconfound these effects. The repeat letter format is much less sensitive to gaze control defects, and somewhat more sensitive to adjacent contour interactions than is the Snellen format. We report that amblyopic eyes can be subdivided empirically into three repeat-letter categories: repeat-letter acuity significantly better than Snellen acuity; repeat letter acuity not significantly different from Snellen acuity; and repeat letter acuity significantly worse than Snellen acuity. We report that this subdivision cuts across the clinical subclassification of amblyopia and also across the crowding/no crowding subclassification. We suggest that, rather than abnormal lateral interactions, defective selection and/or control of gaze is an important factor in depressed visual acuity in amblyopic eyes of the first repeat-letter category but not for the third type, in which abnormal lateral interactions may be important. To test the hypothesis that the response to patching and refractive therapy may be less satisfactory in our first category of amblyopic eyes, we are carrying out a prospective study.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of compensatory head postures after strabismus surgery

PURPOSE

To determine the incidence and relative frequencies of orientations of compensatory head postures (CHP) and success in surgically treating the CHP seen in patients with pure lateral rectus paresis (group I), superior oblique paresis (group II), Duane syndrome (group III), Brown syndrome (group IV), and congenital motor nystagmus (group V).

METHODS

The authors retrospectively reviewed all patients assessed and treated between 1985 and 1991 with these five conditions. Frequencies and orientations of the CHP were determined in all patients in each group. The success of surgery in eliminating the CHP in the subgroups of patients who underwent surgery to treat the CHP also was determined.

RESULTS

The frequencies of CHP were 29.0% of 93 group I cases, 71.2% of 139 group II cases, 68.1% of 91 group III cases, 17.4% of 35 group IV cases, and all 23 group V cases, for an overall incidence of 56.7% of 381 patients. For patients who underwent surgery to eliminate a CHP, success rates were 85.7% of 21 group I cases, 75.6% of 41 group II cases, 87.2% of 47 group III cases, 100% of 5 group IV cases, and 78.3% of 23 group V patients, for an overall success rate of 82.5% of 137 surgical cases.

CONCLUSION

Because CHP is seen frequently in strabismus and nystagmus disorders, ocular causes must be ruled out in any case of an anomalous head posture. Appropriately planned surgery for CHP caused by incomitant strabismus or eccentric nystagmus null zones has a high rate of success in eliminating CHP.

Defective processing of motion-defined form in the fellow eye of patients with unilateral amblyopia

The following three measurements were made on a group of 20 pediatric and 5 adult patients with unilateral amblyopia: (1) speed threshold for recognizing motion-defined dotted letters; (2) recognition acuity for isolated solid letters of 4% contrast; and (3) Snellen line acuity for high-contrast letters. Normal limits were established with a group of 30 pediatric and 10 adult control subjects. The main finding was that, in amblyopic children, a high percentage (83%, 15 of 18) of fellow eyes showed a degraded ability to recognize motion-defined letters, even though Snellen acuity and 4% letter acuity were normal for age. The fellow eyes of all nine patients with strabismic amblyopia showed this pattern of loss, as did four of six fellow eyes of patients with anisometropic amblyopia and two of three fellow eyes of patients with anisometropic plus strabismic amblyopia. Only two clinically unaffected eyes were normal for motion-defined letters. These eyes belonged to patients with anisometropic amblyopia. Eighteen of the 19 previously amblyopic eyes tested were abnormal for motion-defined letters even though Snellen acuity was within normal limits for 6 of these eyes. In adults, only one of five fellow eyes failed the motion-defined letter test. It was concluded that the degradation of form perception associated with amblyopia can be different for luminance-defined and motion-defined form and that defective processing of motion-defined form is common in the fellow eyes of children with unilateral amblyopia.

A functional scoring method for the field of binocular single vision

The authors present a new method for plotting and quantitating the field of binocular single vision (BSV). They modified a Goldmann perimeter to project a fusion target in the form of a cross (+). Unlike previous methods that used a spot, which is a poor fusion target that cannot detect cyclotorsion, the authors' method permits a single tester to plot BSV fields in patients who have any combination of horizontal, vertical, and cyclotorsional diplopia. The BSV fields were plotted in 23 patients with acquired diplopia using both the fusion target and the spot. Scoring was performed using a new scoring template weighted to the functionally important areas around primary and reading positions. Nine patients (39%) had scores for the two targets that differed by more than 10%. The authors' method yields BSV scores that are reproducible and easy to perform and that can be used for preoperative and postoperative assessments, serial monitoring of changes over time, and disability evaluations.

Stability of the postoperative alignment in adjustable-suture strabismus surgery

We reviewed the postoperative alignment drift in 201 patients between the ages of 14 and 75 years who underwent rectus muscle surgery with adjustable sutures from 1984 to 1989. We analyzed results for 42 primary esotropia (ET) surgeries and 37 reoperations (groups IA and IB, respectively), 34 exotropia (XT) primary surgeries and 66 reoperations (groups IIA and IIB, respectively), and 22 hypertropia (HT) surgeries (group III). Forty percent of patients required postoperative muscle adjustment. All patients underwent a minimum of 8-weeks follow up; 66% underwent 6-months follow up or longer. The postoperative drifts in alignment for primary surgeries versus reoperations were not significantly different for either ET or XT patients. The mean postoperative drift in prism diopters from the alignment immediately after the adjustment, or after the surgery if no adjustment was needed, for each group as measured during the most recent follow up was 1.3 eso-shift for group IA, 1.2 exo-shift for group IB, 4.8 exo-shift for group IIA, 4.1 exo-shift for group IIB, and 1.5 hyper-shift for group III. Only for groups IIA and IIB were these drifts found to differ significantly from zero. Based on these drift patterns, we align ET patients to orthotropia, XT patients to 5 to 7 delta esotropic, and HT patients to 1 to 2 delta hypotropic positions.

Treatment of blepharospasm and hemifacial spasm with botulinum A toxin: a Canadian multicentre study

Botulinum A exotoxin was recently approved for use in Canada. We describe the efficacy of botulinum toxin in the management of 235 patients with blepharospasm (mean age 64.3 years) and 130 patients with hemifacial spasm (mean age 60.4 years) treated at three Canadian ophthalmologic centres between 1984 and 1989. A total of 98% of the patients with blepharospasm and 100% of the patients with hemifacial spasm had significant relief of their symptoms; however, 11% of the former and 2% of the latter did not respond to the usual starting concentrations of the drug and needed stronger dosages for relief. The duration of relief varied widely in both groups. Up to 7% of patients had ineffective treatments but responded to subsequent injections. Analysis of variance and linear trend statistics showed that there were no changes in the mean duration of relief over the first several treatments for individual patients in either group. Side effects were transient and included ptosis, exposure keratitis, epiphora and strabismus.

Intraorbital wood. Detection by magnetic resonance imaging

The authors present two cases in which intraorbital wooden foreign bodies remained undetected after initial ophthalmologic examination and radiologic investigation which included plain orbital x-rays, orbital computed tomography (CT) scans, and, in one case, orbital ultrasound. In each case, subsequent magnetic resonance imaging (MRI) showed a well-delineated low-intensity lesion suggestive of a retained foreign body. Investigation of a case of suspected wooden foreign body in the orbit should include an MRI scan if there is no contraindication, and no foreign body has been defined on CT scan, ultrasound, or plain orbital films.

Assignment of the gene for complete X-linked congenital stationary night blindness (CSNB1) to Xp11.3

X-linked congenital stationary night blindness (CSNB) is a nonprogressive retinal disorder characterized by a presumptive defect of neurotransmission between the photoreceptor and bipolar cells. Carriers are not clinically detectable. A new classification for CSNB includes a complete type, which lacks rod function by electroretinography and dark adaptometry, and an incomplete type, which shows some rod function on scotopic testing. The refraction in the complete CSNB patients ranges from mild to severe myopia; the incomplete ranges from moderate hyperopia to moderate myopia. To map the gene responsible for this disease, we studied eight multigeneration families, seven with complete CSNB (CSNB1) and one with incomplete CSNB, by linkage analysis using 17 polymorphic X-chromosome markers. We found tight genetic linkage between CSNB1 and an Xp11.3 DNA polymorphic site, DXS7, in seven families with CSNB1 (LOD 7.35 at theta = 0). No recombinations to CSNB1 were found with marker loci DXS7 and DXS14. The result with DXS14 may be due to the small number of scored meioses (10). No linkage could be shown with Xq loci PGK, DXYS1, DXS52, and DXS15. Pairwise linkage analysis maps the gene for CSNB1 at Xp11.3 and suggests that the CSNB1 locus is distal to another Xp11 marker, TIMP, and proximal to the OTC locus. Five-point analysis on the eight families supported the order DXS7-CSNB1-TIMP-DXS225-DXS14. The odds in favor of this order were 9863:1. Removal of the family with incomplete CSNB (F21) revealed two most favored orders, DXS7-CSNB1-TIMP-DXS255-DXS14 and CSNB1-DXS7-TIMP-DXS255-DXS14. Heterogeneity testing using the CSNB1-M27 beta and CSNB1-TIMP linkage data (DXS7 was not informative in F21) was not significant to support evidence of genetic heterogeneity (P = 0.155 and 0.160, respectively).

Cranial dystonia, blepharospasm and hemifacial spasm: clinical features and treatment, including the use of botulinum toxin

Blepharospasm, the most frequent feature of cranial dystonia, and hemifacial spasm are two involuntary movement disorders that affect facial muscles. The cause of blepharospasm and other forms of cranial dystonia is not known. Hemifacial spasm is usually due to compression of the seventh cranial nerve at its exit from the brain stem. Cranial dystonia may result in severe disability. Hemifacial spasm tends to be much less disabling but may cause considerable distress and embarrassment. Patients affected with these disorders are often mistakenly considered to have psychiatric problems. Although the two disorders are quite distinct pathophysiologically, therapy with botulinum toxin has proven very effective in both. We review the clinical features, proposed pathophysiologic features, differential diagnosis and treatment, including the use of botulinum toxin, of cranial dystonia and hemifacial spasm.

Botulinum toxin injections in the treatment of blepharospasm, hemifacial spasm, and eyelid fasciculations

Seventy-six patients with blepharospasm (mean age 56.9 years) received 248 injection treatments with botulinum A exotoxin (mean 3.1 treatments per patient): 87.0% of treatments led to total relief of spasms for a mean interval of 14.1 weeks. The average duration of response remained fairly constant over the first six injection series, although patients with the most severe spasms had shorter intervals than patients with less severe symptoms. Twenty patients with hemifacial spasm (mean age 56.9 years) received 44 treatments (mean 1.9 treatments per patient): In 93.1% of cases there was total relief of periocular and perioral spasms, with a mean interval of 17.4 weeks. The average duration of response for the third series of treatments was much shorter than the mean durations for the first two treatments. Side effects were always transient and included ptosis (23.3%), dry eyes (18.1%), tearing (5.5%), and strabismus (1.4%). No patient had a systemic reaction to the drug. Chronic benign eyelid fasciculations were also successfully treated in 3 patients with single treatments.

A surgical approach for Duane syndrome

Duane retraction syndrome (DRS) represents a spectrum of motility disorders in which the common feature is retraction of the affected eye on attempted adduction. Electrophysiologic and neuropathologic studies have shown that the underlying cause is anomalous innervation of the lateral rectus with the medial rectus and, at times, with vertical muscles in the affected eye. Clinical abnormalities observed in DRS can include any or all of the following: a deviation in the primary position; abnormal head position; severe retraction causing a pseudoptosis; and upshoots and/or downshoots associated with A, V, or X patterns. A surgical approach based on the analysis of these four features is presented, allowing the surgeon to devise an appropriate, individualized plan for a given case which can yield optimal results in one operation.

Functional scoring of the field of binocular single vision in patients with diplopia

A simple method for scoring the field of binocular single vision (BSV) is presented. The field is plotted on the Goldmann Perimeter using the III-4e target. The method gives greater weight to functionally important areas, especially the primary and reading positions. Several cases illustrate the application of the proposed scoring system by correlating patients' subjective disabilities with their diplopia scores. The method is more precise than any previous scheme and provides a quantitative measure that makes the examination of patients with diplopia more accessible to legal evaluation and numerical analysis.

Traumatic hyphema in children. Treatment with epsilon-aminocaproic acid

Forty-nine patients, ages 3 to 18 years, who sustained nonpenetrating unilateral trauma with hyphemas were assigned randomly to receive either 100 mg/kg of epsilon-aminocaproic acid (EACA), an antifibrinolytic agent, orally every 4 hours for 5 days (maximum 30 g/day) or a placebo. No patients ingested acetylsalicylic acid (ASA)-containing compounds before or during admission. Two patients of 24 treated with EACA and 1 of 25 given placebo had rebleeds. The hyphemas in the EACA-treated group took significantly longer to clear (mean, 5.3 versus 2.6 days; P less than 0.001). Because of the low incidence of rebleeds in the placebo group, the efficacy of EACA in reducing the rate of rebleeds could not be determined. Further studies with this drug, controlling for age, race, sickle trait, and pre-admission antiplatelet agents should be undertaken before its routine use in traumatic hyphema management can be recommended.

The rat electroretinogram in combined zinc and vitamin A deficiency

To assess the relative importance and interdependence of zinc and vitamin A in retinal function, a group of 36 male Wistar rats were raised in dim illumination and deprived of both zinc and vitamin A (Z-A-) for 90 days (Phase I) until they lost weight and showed signs of both vitamin A and zinc deficiency. Scotopic electroretinograms (ERGs) showed an average 1.5 log unit elevation in light intensity needed to elicit a 200 microV b-wave (criterion intensity) as compared to a control-pair-fed group of rats. Tissue samples from the Z-A- rats showed undetectable liver vitamin A (less than 10 micrograms/g) and a significantly decreased level of femur zinc compared to the control group (P = 0.02). There was photoreceptor outer segment degeneration and loss of cells in the outer nuclear layer of the retina. For Phase II the 24 surviving rats were randomized into three treatment groups--one group remained vitamin A-deficient (A-) but received zinc and retinoic acid, the second remained zinc-deficient (Z-) but received vitamin A and retinoic acid, and the third group was repleted with both zinc and vitamin A (Z+A+) and also received retinoic acid. ERGs were performed 30 and 60 days after randomization. The criterion intensity of the Z+A+ and Z- groups approached normal by 60 days, while that of the A- rats deteriorated a further 1.0 log unit. Histologic studies of the A- rats showed abnormalities in cornea, photoreceptor outer segments, and gut mucosa. All animals had testicular atrophy. Vitamin A repletion significantly reverses retinal degeneration from the Z-A- state even in the presence of moderate zinc deficiency. Zinc supplementation alone does not prevent ongoing retinal degeneration from severe vitamin A deficiency.

Masked bilateral superior oblique palsy: clinical features and diagnosis

Ninety-two patients treated surgically between 1972 and 1983 were diagnosed initially as having a unilateral superior oblique palsy (SOP). On follow-up, eight (8.7%) developed findings of an SOP of the other eye. Such patients have "masked bilateral" superior oblique palsy. All eight patients had unilateral inferior oblique weakening with or without contralateral inferior rectus recession as the initial surgery. The "unmasking" of the contralateral palsy manifested in seven cases by an overaction of the contralateral inferior oblique muscle and appeared an average of 9.8 weeks (range five days to 11 months) after the first surgery. Their preoperative mean V-shift (7.6 diopters), mean excyclotorsion (5.7 degrees), and mean difference of hyperdeviation on right versus left tilt (19.6 diopters) were not significantly different from the respective values for patients with unilateral SOP (5.0 diopters, 4.3 degrees, 19.0 diopters).

Four-muscle surgery for infantile esotropia with V-pattern

Inferior oblique overaction is frequently seen with infantile esotropia. In patients with infantile esotropia and V-pattern with moderate to large inferior oblique overactions, the oblique weakening can be combined with horizontal muscle surgery. Eighteen patients with infantile esotropia and V-pattern underwent bilateral inferior oblique recessions with bilateral 5.0-mm medial rectus recessions. Sixty-one patients with infantile esotropia underwent bilateral 5.0-mm medial rectus recessions alone. At 2 years' follow-up, the patients who had undergone medial rectus recessions alone showed, on average, 12.9 dioptres more reduction in esodeviation at distance and 13.4 dioptres more reduction at near in primary position than did those who had undergone 4-muscle surgery (P = 0.03). Only 2 of the 18 patients (11%) who had undergone 4-muscle surgery developed an A-pattern postoperatively.

Botulinum toxin injection in the management of lateral rectus paresis

Seventeen patients with lateral rectus paresis (3 bilateral) were treated by injection of botulinum toxin to the antagonist medial rectus to eliminate its unopposed action or to eliminate its contracture. This allowed maintenance of single binocular vision in most patients while waiting for the palsy to heal, especially important in two children. It allowed avoidance of surgery in some cases, and a reduction or elimination of medial rectus surgery when later intervention was needed for persistent paralysis. The release of medial rectus shortening and stiffness (contracture) after just a few days of denervation was unexpected. This implies an internal muscular mechanism of contracture, perhaps sarcomere overlap, different from the fibrotic changes found in muscles after inflammation or trauma. These results also provide a rationale for experimental denervation treatment of contracture in limb muscle disorders.

Megalocornea: a clinical and echographic study of an autosomal dominant pedigree

A family with autosomal dominant megalocornea was studied clinically and echographically. The anterior chamber angles, intraocular pressures and axial lengths were all normal. These findings strongly support the dualist proposition which contends that etiologically, megalocornea and congenital glaucoma are distinct.

Orbital hypotelorism. An isolated autosomal dominant trait

Four patients from three consecutive generations of a family with ocular hypotelorism are described. Radiographs document a subnormal distance between the medial orbital walls. To our knowledge, this is the first report of heritable isolated orbital hypotelorism. The pedigree is consistent with an autosomal dominant disorder.

Surgical treatment of compensatory head position in congenital nystagmus

Records of 32 patients with congenital nystagmus who underwent surgery for a significant head turn were reviewed to assess the effectiveness of current surgical approaches. Eighteen patients (Group I) had single binocular vision and had bilateral recess/resect procedures either according to Parks' 5-6-7-8 scheme (nine patients) or "augmented" from 10% to 40% for large head turns (nine patients). Fourteen (78%) had a reduction of the turn to 15 degrees or less, six (33%) being 5 degrees or less. One was overcorrected . Fourteen patients had a heterotropia in addition to head turn. Seven (Group II) had bilateral surgery to attempt to correct the head turn and reduce the tropia to less than 10 prism diopters. In three cases (43%) there was both successful treatment of the tropia and reduction of the turn to 15 degrees or less. The tropia was successfully treated in six patients (86%). In seven patients (Group III) monocular recess/resect surgery was done to attempt to correct both abnormalities. In four (57%) the turn was reduced to 15 degrees or less with successful treatment of the tropia at the same time. Five (71%) had a tropia of less than or equal to 10 diopters postoperatively. Overall, the head turns were reduced to 15 degrees or less in 23 (72%) of the 32 patients including 11 (35%) with 5 degrees or less residual turn. Three (9%) were overcorrected at least 10 degrees. The frequency of undercorrections indicates that larger amounts of surgery have to be done, especially for large turns, although ductions will be limited in some gaze positions, at times significantly, to achieve this goal.

Silicone tube intubation in disorders of the lacrimal system in children

We analyzed the results of 81 silicone intubations of the lacrimal system in 56 patients aged 6 months to 16 years after posttreatment follow-up of at least two months. Standard probing just before intubation allowed us to group cases by obstruction sites: proximal, distal, or combined. Overall, the outcome was successful in 65 (80.3%) cases. In cases of trauma, success was achieved in two of five patients with proximal, five of nine patients with distal, and two of two patients with combined obstructions. In nontraumatic blockages, we achieved success in 13 of 16 proximal, 30 of 35 distal, and 13 of 14 combined obstructions.