Cerebral microembolization during pediatric scoliosis surgery: a transcranial doppler study.

SUMMARY: The goal of this study was to identify cerebral microemboli during scoliosis surgery and their potential relationship with visual alterations. Transcranial Doppler identified high-intensity transient signals (HITS) during surgery in both middle cerebral arteries, and ophthalmologic examination assessed their potential effects on the visual system. Thirteen children (age 13-17 years) undergoing surgery for scoliosis or kyphosis with spine curvature >45 degrees were studied. HITS were identified in 92%. Eleven patients had a total count of <15 HITS, but in the remaining two the count was unexpectedly high (63 and 265 HITS). Echocardiography in these two patients indicated the presence of an atrial right-to-left shunt. Uneventful preoperative and postoperative visual function was found in 11 patients. One patient had preoperative blindness and in another ophthalmologic complications developed not related to microembolization. Scoliosis surgery is frequently associated with low counts of cerebral microemboli. It appears that such low embolic counts have no effects on postoperative visual function as determined clinically. Some patients may show high rates of microemboli, which may be related to the presence of right-to-left cardiac shunts. The impact of these signals on brain function remains to be investigated.

Topical versus intravenous administration of tranexamic acid: a comparison of intraocular and serum concentrations in the rabbit.

BACKGROUND: Tranexamic acid has been shown to greatly reduce the incidence of secondary hemorrhage when administered orally or intravenously. Topical administration of the drug should result in much lower serum concentrations, with fewer adverse effects. We performed a study to determine whether topical application of tranexamic acid would yield higher intraocular concentrations and lower serum concentrations of drug than intravenous administration. METHODS: Ten New Zealand white rabbits received 25 mg/kg of tranexamic acid intravenously every 8 hours for 3 days. Another group of 10 rabbits received one drop (0.05 mL) of commercially available tranexamic acid solution (100 mg/mL) every 8 hours for 3 days to one eye. Tranexamic acid levels in the aqueous humour, vitreous humour and serum 1 hour after administration of the last dose of drug were determined. RESULTS: Analysis of variance showed that aqueous concentrations of tranexamic acid were significantly higher with topical delivery than with intravenous administration (15 vs. 9 micrograms/mL)(p < 0.05). Serum concentrations were significantly lower following topical administration (9 vs. 19 micrograms/mL)(p < 0.01). The drug was not detected in the vitreous humour in either group. INTERPRETATION: Topical delivery of tranexamic acid may prove to be valuable in yielding therapeutic intraocular concentrations of drug in patients with hyphema while minimizing systemic toxicity.

Evaluation of a hand-held autorefractor in children younger than 6.

PURPOSE: To evaluate a hand-held portable autorefractor in a pediatric population and compare results with those found on retinoscopy by experienced pediatric retinoscopists. METHODS: One-hundred and two children aged 5 to 72 months were examined with and without cycloplegia using an autorefractor, and the results compared with those found on standard retinoscopy by two ophthalmologists masked as to the autorefractor findings. Results were converted from conventional notation using plus cylinder to the h-space notation and compared in three-dimensional h-space. RESULTS: There was remarkable agreement between the results found by autorefraction and manual retinoscopy using loose lenses or a phoropter. The findings were similar both for sphere and cylinder across the age ranges studied. CONCLUSIONS: The Nikon Retinomax is an accurate instrument to estimate refractive error in children younger than 6 and could prove useful in the office, the operating room, or as a screening device.

Retinal perforation in strabismus surgery.

PURPOSE: Perforation of the retina is a major complication of strabismus surgery. The reported incidence of perforation varies from 0.13% to 12%. This study was undertaken to determine, from a large collaborative database, the incidence of suspected and unsuspected retinal and choroidal injury in pediatric horizontal muscle surgery. METHOD: All children with horizontal strabismus surgery seen between September 1992 and October 1995 were examined with Indirect ophthalmoscopy immediately following their procedure. Surgery was performed by both resident and attending physicians. Cases involving muscle reoperation, high myopia, or patients with connective tissue disorders were excluded. RESULTS: Strabismus surgery was performed on 765 patients, who underwent 1129 muscle recessions and 349 muscle resections. These children also had 161 vertical or oblique muscle procedures performed. Intraocular trauma resulting from horizontal muscle surgery was noted in 14 patient, including three retinal perforations. One of these patients was treated with cryotherapy; the other two received no therapy other than intraoperative and postoperative antibiotics. DISCUSSION: The incidence of retinal perforation was 0.4% and the incidence of choroidal injury without perforation was 1.4% in this large series of children undergoing horizontal strabismus surgery. Retinal detachment or endophthalmitis did not develop during the 6-week follow-up period.

Air guns: the main cause of enucleation secondary to trauma in children and young adults in the greater Ottawa area in 1974-93.

OBJECTIVES: To determine the proportion of enucleation procedures attributable to injuries from air guns in people aged 18 years or less and to identify the associated pathological findings. DESIGN: Case series. SETTING: Ophthalmic Pathology Registry, University of Ottawa, and affiliated Children's Hospital of Eastern Ontario (Ottawa), Ottawa General Hospital and Ottawa Civic Hospital. In addition, information on air gun injuries from April 1990 to December 1993 was obtained from the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP) database, with data from 10 pediatric and 5 general hospitals across Canada. PATIENTS: All patients aged 18 years or less who underwent enucleation between Jan. 1, 1974, and Dec. 31, 1993. RESULTS: Eighty-five patients were identified as having undergone enucleation. Trauma accounted for 51 cases (60%), of which 13 (25%) were caused by air guns, the largest single cause of enucleation secondary to trauma. Overall, air gun injuries accounted for 15% of enucleation procedures, whereas retinoblastoma accounted for 21%. All air gun injuries were in boys (median age 14 years, range 9 to 16 years). Of the 13 eyes with air gun injuries 7 had ocular perforation and 6 had ocular penetration. In all cases the intraocular structures were severely disrupted. The CHIRPP database included 165 air gun injuries; 32 were to the eye or ocular adnexa, resulting in 26 hospital admissions. CONCLUSIONS: Air guns were the largest single cause of enucleation secondary to trauma in our study. These guns are widely available in Canada and are unrestricted at muzzle velocities capable of causing death or serious injury, especially to the eye. We feel that air guns should be licensed only to people aged 16 to 18 years or older and that education in their use should be mandatory.

Pseudohypopyon in acute myelogeneous leukemia.

An 11-month-old boy presented with uniocular hypopyon, elevated intraocular pressure, and iris nodules. A differential diagnosis of physical abuse, infection, retinoblastoma, juvenile xanthogranuloma, and histiocytosis X were considered but initial physical and laboratory investigations all had normal results. Three weeks following initial presentation, the child developed fulminant acute myelogenous leukemia. The clinical course, investigations, and outcome are reviewed.

Ocular findings in acromesomelic dysplasia.

We examined an infant who had prenatal onset of a skeletal dysplasia that had many features in common with acromesomelic dysplasia, including the clinical and light and electron microscopic findings of both corneas. Successful lamellar keratoplasty was performed on the left eye when histologic examination of the corneal button from the right eye showed that the corneal scar was only of partial thickness.

Persistent tunica vasculosa lentis as a sign of congenital myotonic dystrophy.

We describe the ocular findings in eight patients with congenital myotonic dystrophy in the newborn period. While three infants had normal findings, five infants had evidence of persistent tunica vasculosa lentis (TVL) at gestational ages ranging from 34 to 40 weeks. Atrophy of vessels on the anterior lens capsule is normally complete by 34 weeks gestation and its persistence should suggest congenital infection or congenital myotonic dystrophy. Diagnosis of myotonic dystrophy has serious implications for the baby and the mother, in whom the condition may have not been recognized earlier.

Outpatient treatment of microscopic and rim hyphemas in children with tranexamic acid.

Twenty-one patients aged 4 to 15 years with microscopic or rim hyphemas were treated as out-patients with systemic tranexamic acid therapy. The protocol included limited activity at home, topical steroid therapy, no dilating drops, patching for comfort or surface abrasions only, and follow-up every 24 to 48 hours. With this regimen no patient had a secondary hemorrhage. The incidence of associated injuries was surprisingly high, including four patients with angle recession, two with choroidal ruptures and four with commotio retinae, two of whom manifested retinal holes, requiring cryotherapy. We conclude that tranexamic acid therapy decreases the risk of secondary hemorrhage in ambulatory patients with hyphema, but careful assessment and follow-up are necessary to rule out associated ocular injury.

Brown's syndrome with contralateral inferior oblique overaction: a possible mechanism.

The simultaneous occurrence of Brown's syndrome in one eye and inferior oblique overaction in the other eye is an infrequently reported association. Review of our series of 38 cases of Brown's syndrome disclosed six patients with overaction of the contralateral inferior oblique, of whom four stepped out to contralateral superior oblique palsy. We propose that these patients initially have bilateral Brown's syndrome in infancy, and spontaneous resolution occurs in one eye only. While Brown's syndrome is present the antagonist inferior oblique muscle undergoes isometric contracture. With spontaneous resolution of Brown's syndrome a relative imbalance of forces occurs, with the superior oblique muscle now being relatively paretic compared with the contracted and fibrotic inferior oblique. Up-shoot in adduction then becomes apparent.

Totally asymptomatic inferior oblique overaction.

Seventeen children were demonstrated to have completely asymptomatic overaction of one or both inferior oblique muscles. None had a constant vertical deviation in primary position, up gaze or down gaze, and significant patterns were absent. None had diplopia or complaints of torsion. The Bielschowsky head tilt test gave a negative result in all cases. No patient showed excyclorotation on fundus examination. Long-term follow-up (28 to 134 [average 75.6] months) of 13 of the patients showed that the condition did not worsen with time and may not require surgical weakening of the inferior oblique muscle.

Oral administration of tranexamic acid in the management of traumatic hyphema in children.

In a prospective study 163 patients aged 17 years or less admitted to a children's hospital between April 1985 and December 1990 with traumatic hyphema were treated with tranexamic acid, 25 mg/kg given orally every 8 hours to a maximum of 1500 mg every 8 hours for 5 days. Secondary hemorrhage occurred in 5 patients (3%), none of whom had more than one rebleeding episode. In contrast, 24 (8%) of 316 patients aged 17 years or less admitted to the same hospital between January 1977 and March 1985 with traumatic hyphema who were not treated with antifibrinolytics had a secondary hemorrhage, several more than once, giving a rebleeding rate of 33/316 (10%). The results suggest that tranexamic acid reduces the incidence and number of secondary hemorrhages in children, without significant ocular or systemic side effects.