Subjective and objective outcomes of strabismus surgery in children

BACKGROUND

The negative psychosocial impact of strabismus in adults has been well documented. Despite the increasingly recognized importance of outcomes research, parents' satisfaction with strabismus treatment in childhood and their assessment of its functional impact and "quality of life" impact have not been investigated.

METHODS

A survey instrument was designed to assess parents' perceptions of preoperative, surgical, and postoperative phases of the clinical experience, including the long-term impact of surgery on their children.

RESULTS

Overall satisfaction with the surgical result was rated "good" or "very good" in 85% of 77 children under age 6. The correlation between subjective satisfaction and objective alignment within 10 prism diopters (delta) of orthophoria was significant (P < .001). Parents of children under age 4 noted improved eye contact (61%) and appearance (94%). Parents of older children noted improved interactions with others (47%) and self-esteem (55%). Coordination was considered improved in 56% of the entire group. Subjective satisfaction and psychosocial benefits often occurred even in cases deemed objectively unsuccessful.

CONCLUSION

Surgical correction of strabismus in childhood is clearly perceived by parents to be both successful and important to them and their children.

Common themes in redox chemistry emerge from the X-ray structure of oilseed rape (Brassica napus) enoyl acyl carrier protein reductase

BACKGROUND

Enoyl acyl carrier protein reductase (ENR) catalyzes the NAD(P)H-dependent reduction of trans-delta 2-enoyl acyl carrier protein, an essential step in de novo fatty acid biosynthesis. Plants contain both NADH-dependent and separate NADPH-dependent ENR enzymes which form part of the dissociable type II fatty acid synthetase. Highly elevated levels of the NADH-dependent enzyme are found during lipid deposition in maturing seeds of oilseed rape (Brassica napus).

RESULTS

The crystal structure of an ENR-NAD binary complex has been determined at 1.9 A resolution and consists of a homotetramer in which each subunit forms a single domain comprising a seven-stranded parallel beta sheet flanked by seven alpha helices. The subunit has a topology highly reminiscent of a dinucleotide-binding fold. The active site has been located by difference Fourier analysis of data from crystals equilibrated in NADH.

CONCLUSIONS

The structure of ENR shows a striking similarity with the epimerases and short-chain alcohol dehydrogenases, in particular, 3 alpha,20 beta-hydroxysteroid dehydrogenase (HSD). The similarity with HSD extends to the conservation of a catalytically important lysine that stabilizes the transition state and to the use of a tyrosine as a base--with subtle modifications arising from differing requirements of the reduction chemistry.

Alignment success following medical rectus recessions in normal and delayed children

Others have suggested that developmentally delayed children, who are frequently esotropic, have a poor prognosis following esotropia surgery. To date, no comparison of success rates in normal and delayed children following similar surgery has been made. We compared our long-term results following graded bilateral medial rectus recessions in consecutive normal (n = 62) and delayed (n = 29) children. We defined success as alignment maintained within 10 delta of orthophoria. Survival curves were compared using the Mantel-Haenszel statistic. Delayed children had a significantly poorer outcome (p = .05) throughout follow up, which ranged from 12 to 120 months (mean = 24 months). Early in the period of study, we observed a large proportion of overcorrections among the delayed children. Subsequent modification in the amount of surgery performed appeared to improve the initial and long-term success in these children. We conclude that delayed children do have a poorer prognosis than normal children following medial rectus recession. This prognosis may be improved by more conservative amounts of surgery.

Steroid injection versus conservative treatment of anisometropia amblyopia in juvenile adnexal hemangioma

Because of serious side effects, the indications for intralesional steroid injection of adnexal hemangiomas are unclear. Of 23 children with such lesions who were examined over a period of 9 years, 9 had no evidence of amblyopia and needed no intervention. Five required steroids intralesionally and/or systemically because of threatened occlusion of the pupillary axis. The remaining 9 were considered at risk of anisometropic amblyopia because of induced astigmatism: 5 received injections and 4 were treated with glasses and/or patching alone. The visual, refractive, and cosmetic results of the injected and conservatively managed anisometropes were similar. We recommend that steroid injection be reserved for patients with threatened occlusion of the visual axis and for those with severe astigmatism or amblyopia refractory to conservative management.

Exaggerated effect of bilateral medial rectus recession in developmentally delayed children

Many have suggested that the esotropia associated with developmental delay should be considered separately. However, the esotropia surgery recommended for developmentally delayed children has been similar to that performed in normal children. We have noticed a tendency for developmentally delayed children to develop consecutive exotropia following bilateral medial rectus recessions. Of 94 children undergoing such surgery between 1981 and 1991, 31 were developmentally delayed. Follow up ranged from 7 months to 202 months (mean 24 months). Surgical effect, defined as the change in alignment following each amount of surgery, was greater in the developmentally delayed group than in control subjects (P = .002). The increase in effect of the same amount of surgery in a developmentally delayed patient averaged 5.28 prism diopters, but was much larger in specific instances. Variability of effect was more marked among developmentally delayed children. We conclude that bilateral medial rectus recessions in developmentally delayed children may be better postponed in some cases, deferred for smaller angles, or decreased in amount.

Idiopathic tractional corectopia

Four infants were referred for congenital unilateral corectopia. In each case, the abnormal position of the pupil was caused by a fibrous structure that tethered the iris pupillary margin to the peripheral cornea. No patients showed characteristics of intrauterine infection, Rieger anomaly, ectopia lentis et pupillae, or iris coloboma. Amblyopia was not present in any of the patients. Three children demonstrated progression of the corectopia in the first 6 months of life. Two who developed shallow anterior chambers were treated surgically, one with an Nd:YAG laser and the other with incisional surgery. The third was treated with medical mydriasis. All four children have had favorable visual outcomes to date. The origin of the tethering strands is unclear but may be related to incomplete regression of vessels from the embryologic vascular system. We recommend medical or surgical intervention for unilateral corectopia when the pupillary aperture is displaced peripheral to the central visual axis or when the position of the iris threatens angle structures. Prophylactic occlusion therapy may also be indicated.

Crystallization of the NADH-specific enoyl acyl carrier protein reductase from Brassica napus

The tetrameric, NADH-dependent enoyl acyl carrier protein reductase from developing seeds of Brassica napus (oil seed rape) has been crystallized from solutions containing ammonium sulphate as the precipitant in the presence of NAD+ or NADH using the hanging drop method of vapour diffusion. The crystals belong to the tetragonal system and are in space group P4(2)2(1)2 with cell dimensions a = b = 70.5 A, c = 117.8 A. Considerations of the possible values of Vm indicate that the asymmetric unit contains a single subunit. The crystals are resistant to radiation damage and X-ray diffraction photographs taken with synchrotron radiation show measurable reflections to beyond 1.9 A resolution. Determination of the structure of this enzyme will advance the understanding of the mechanisms of lipid biosynthesis in plants and provide an opportunity to study the interactions between this enzyme and its acyl carrier protein substrate.

Bilateral lateral rectus recession for exotropia: a survival analysis

Exotropia may progress during the childhood years, and the ideal time for surgical intervention remains uncertain. We reviewed our results following bilateral lateral rectus recession in 57 consecutive patients. In order to identify possible predictive covariates, we performed survival analysis using survival time as the time from surgery to failure. The patients' age at the time of surgery ranged from 11 months to 50 years (mean, 68 months). Follow up after surgery ranged from 1 to 105 months (mean, 47 months). Outcomes were considered failures if there was (1) a distance exodeviation greater than 10 prism diopters at any time after surgery, (2) a distance esodeviation greater than 10 delta more than 6 months postoperatively, or (3) further surgery for exotropia or esotropia. By these criteria, surgery was successful in 58% of cases. Results of the survival analysis indicated an estimated mean time to failure of 68 months. Patients with intermittent exotropia were more likely to remain aligned postoperatively than were those with constant deviations. The age at onset of exotropia, age at surgery, angle of deviation at different fixation distances, early postoperative alignment, and presence of symptoms, amblyopia, anisometropia, or incomitance before surgery were not predictive of success. We conclude that exotropia surgery may be performed with the same likelihood of success at any age, but patients with intermittent deviations do better.

Studies on wheat acetyl CoA carboxylase and the cloning of a partial cDNA

Wheat germ acetyl CoA carboxylase (ACCase) was purified by liquid chromatography and electroelution. During purification bovine serum albumin (BSA) was used to coat Amicon membranes used to concentrate partially pure ACCase. Despite further SDS-PAGE/electroelution and microbore HPLC steps BSA remained associated. This presented serious protein sequencing artefacts which may reflect the affinity of BSA for fatty acids bound to ACCase. To avoid these artefacts the enzyme was digested in gel with Endoproteinase LysC protease without the presence of BSA, and the resulting peptides blotted and sequenced. A partial cDNA (1.85 kb) encoding ACCase from a wheat embryo library was cloned, which hybridised to a 7.5 kb RNA species on northern blot of wheat leaf poly(A)+ RNA. The partial cDNA therefore represents about 0.25 of the full-length cDNA. The clone was authenticated by ACCase peptide sequencing and immuno cross-reactivity of the overexpressed clone. The derived amino acid sequence showed homology with both rat and yeast ACCase sequences (62%). Antibodies raised against wheat acetyl CoA carboxylase were specific for a 220 kDa protein from both wheat embryo and leaf. In addition, by using a novel quick assay for ACCase that utilised 125I-streptavidin, we showed the major biotin containing protein to be 220 kDa in both leaf and germ. This is in marked contrast to the previously published molecular mass of 75 kDa allocated to wheat leaf ACCase.

Development of object vision in infants with permanent cortical visual impairment

We examined 30 infants in whom cortical visual impairment was diagnosed during their first year of life to ascertain prognostic factors for the development of object vision, defined as the ability to recognize faces or hand-held toys. All patients were followed up for a minimum of 12 months. The most common causes of cortical visual impairment in the 30 infants were hydrocephalus in nine infants (30.0%), birth asphyxia or neonatal hypoxia in eight infants (26.7%), intracranial hemorrhage with or without hydrocephalus in seven infants (23.3%), and meningitis in five infants (16.7%). Lack of development of object vision was associated only with hypoxia (P = .013). Findings on ophthalmic examination, an abnormality in the visual pathway on computed tomographic or magnetic resonance scan, and seizures, hydrocephalus, intracranial hemorrhage, meningitis, cerebral palsy, developmental delay, prematurity, microcephaly, and hearing deficit, did not appear to be risk factors for the lack of development of object vision.

Recognized scleral perforation during eye muscle surgery: incidence and sequelae

Inadvertent perforation of the sclera is a widely recognized complication of eye muscle surgery. In the 1960s and 1970s, it was estimated to occur in 9% to 12% of patients operated. Fortunately, dreaded vision-threatening sequelae have been much less common. To better define the occurrence and sequelae of this complication, we sent a questionnaire to all 342 members of the American Association for Pediatric Ophthalmology and Strabismus. Scleral perforations, defined to include known retinal damage, occurred in 728 of nearly 554,000 eye muscle procedures performed by 223 surgeons. Perforations were two times more common with residents or fellows operating. They occurred not only during muscle reattachment (633 cases), but also during muscle disinsertion (24 cases), muscle dissection (6 cases), passage of traction sutures beneath the lateral rectus (5 cases), and preplacement of muscle sutures (5 cases). Many other perforations may have been unrecognized and uncounted. Visual loss was uncommon, occurring in only nine patients. Fourteen retinal detachments included four cases with partial and two with total loss of vision. Only three cases of endophthalmitis occurred, one resulting in partial visual loss and two in total visual loss. Techniques suggested by respondent surgeons to avoid perforations are discussed.

Cell-bound and extracellular phosphatase activities of cyanobacterial isolates

Fifty cyanobacterial strains (10 genera) were tested in batch culture for their ability to use organic phosphorus compounds (1 mg liter(-1) P) as their sole P source. Two monoesters, Na2-β-glycerophosphate and π-nitrophenyl phosphate (πNPP), supported growth of all strains, and the diester bis-π-nitrophenyl phosphate (bis-π-NPP) and herring sperm DNA supported almost all strains. ATP was either a very favorable or poor P source and failed to support growth of nine strains, seven of which were Rivulariaceae with trichomes ending in a hair or long tapered region. Phytic acid was in general the least favorable P source.P-limited cultures grown initially with inorganic phosphate to conditions of P limitation were also tested for cell-bound and extracellular phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities at two pH values (7.6, 10.3) using πNPP and bis-πNPP as substrates. Cell-bound PMEase was inducible in all strains and cell-bound PDEase in most strains. Most showed extracellular PMEase, but not extracellular PDEase. The highest values (μM πNPP or bis-πNPP hydrolyzed mg dry weight(-1) hour(-1)) all occurred in strains ofGloeotrichia as follows: cell-bound PMEase at pH 7.6, 2.7 μM in strain D602; cell-bound PMEase at pH 10.3, 5.2 μM in D602; extracellular PMEase at pH 7.6, 0.73 μM in D281; extracellular PMEase at pH 10.3, 6.6 μM in D281; cell-bound PDEase at 7.6, 0.40 μM in D613; cell-bound PDEase at pH 10.3, 1.0 μM in D613.The results were compared to see if they indicated possible relationships between phosphatase activity and taxonomic or ecological grouping. The following differences were significant (P<0.05). Rivulariaceae produced higher yields than filamentous non-Rivulariaceae with β-glycerophosphate, πNPP, and DNA. Rivulariaceae with the ability to form hairs in culture showed poorer growth in ATP than non-hair-forming Rivulariaceae, but were more effective at utilizing phytic acid. Strains from calcareous environments had higher PMEase activity at pH 10.3 than strains from noncalcareous environments (P<0.01).

Preferential looking and recognition acuities in clinical amblyopia

Although others have noted a correlation between grating and recognition acuities (RA) when both tests are performed on the same day, the value of preferential looking (PL) in predicting eventual visual outcome has not been studied. PL acuities of 64 preverbal patients considered at risk of amblyopia were measured. When these children became verbal, their visual acuities were determined using standard recognition acuity tests. Based on intervening amblyopia treatment between PL and RA measures, 40 patients were designated the minimal treatment group (MTG) and 24 the intensive treatment group (ITG). Chi-square analysis for the MTG showed agreement (P less than .005) between PL and RA in identifying better, equal, and worse eyes. Interocular ratios of PL and RA were significantly correlated for the MTG (P less than .001), but not for the ITG. Monocularly, a consistent correlation between PL and RA was not found. Our data suggest that PL is predictive of recognition acuity in patients whose visual acuity was expected to remain stable.

Glaucoma after pediatric lensectomy/vitrectomy

Glaucoma after pediatric cataract surgery, once well recognized, now occurs only rarely after modern lensectomy/vitrectomy. The authors performed directed glaucoma evaluations of 34 eyes of 26 children. Based on intraocular pressures of 26 mmHg or greater, glaucoma was diagnosed in 8 (24%) eyes of 7 (27%) children. Glaucoma was found more commonly among children followed more than 60 months and was diagnosed up to 105 months after surgery. Typically, the glaucoma was open angle and asymptomatic. Four children had had previously normal pressures recorded. With longer follow-up, it is likely that more children will be diagnosed with glaucoma after lensectomy/vitrectomy procedures. The authors believe such patients should be followed as glaucoma suspects for the rest of their lives.

Variable expression of albinism within a single kindred

We studied the albinotic characteristics in 13 members of a white family (age range, 2 to 73 years), which were graded according to severity and were correlated with visual acuity. Clinical, electrophysiologic, and biochemical characteristics of this family do not fit any known category of human albinism. The degree of heterogeneity in expression of albinotic features was unexpected. The correlation between visual acuity and nystagmus was particularly strong. The brown-haired propositus had severe skin involvement, iris transillumination, fundus hypopigmentation, and foveal hypoplasia. He had no manifest nystagmus, however, and his visual acuity was nearly normal. These observations suggest that nystagmus imposes a visual deficit beyond that related to foveal hypoplasia alone.

When is it safe to stop patching?

Prior reports indicate that about half of amblyopia patients successfully treated with occlusion subsequently require maintenance patching. This retrospective study was designed to discover what clinical characteristics might be associated with a stable outcome following primary occlusion. Included were 188 patients who: (1) had amblyopia related to strabismus, anisometropia or media opacity; and (2) were followed up for at least one year after successful primary occlusion. Patients who did not comply with treatment or who did not achieve equal vision were excluded. Their ages ranged from 2 to 119 months (mean 29 months). Eighty-eight patients (47%) who required no further occlusion were designated the clinically stable group (CSG). The remaining 100 (53%), who subsequently needed patching because of unequal acuities, constituted the maintenance patching group (MPG). CSG patients were older at the beginning (mean 33 months) and at the end (mean 40 months) of primary occlusion than were MPG patients (means 26 and 31 months). Primary occlusion was more likely to have been discontinued because of equal recognition acuities in CSG patients, while equal fixation behaviour or preferential looking was more likely in MPG patients. Distribution of diagnoses, severity of amblyopia at presentation, and length of follow-up were similar in the two groups. Visual outcomes at last follow-up were slightly better in the CSG (p = 0.002). We conclude that, in general, patching can be safely discontinued after the third birthday. Although follow-up after primary occlusion is important to ensure stable results in all patients, preverbal children are more likely to require maintenance patching.

Functional eyelid pulling in children

Five children (three girls and two boys, aged 3 1/2 to 9 1/2 years) were referred by their pediatricians for evaluation of intermittent pulling on their eyelids. All the children were free of systemic disease. One child wore spectacles for accommodative esotropia but no child had evidence of an acute ocular disorder. The duration of symptoms before examination ranged from one to 13 months. None of the parents were able to identify temporally related stressful events. Reassurance alone was given to both parents and children; eyelid pulling resolved in all cases within two weeks. In only the youngest patient did eyelid pulling recur and no child developed other symptoms during a follow-up of six to 15 months. Following resolution, parents believed their children pulled on the eyelids to gain attention or because their eyes were initially irritated and they then developed a "bad habit." Children said they did it to "look funny" or because their "eyes were not opening enough."

Optic disk elevation in Down's syndrome

Of five children who had Down's syndrome with optic nerve head elevation, without associated intracranial lesions, three underwent enhanced computed tomography for which no abnormalities were found. Partial, complete, or intermittent resolution of the optic disk elevation occurred in three children. In none of the children were retinal vessel dilation, splinter hemorrhages, optic nerve drusen, subsequent optic atrophy, or apparent visual loss noted. All of the children were hyperopic, but only one child had a hyperopia of greater than 3.50 diopters.

Binocularity following surgery for secondary esotropia in childhood

Binocularity was assessed in children who developed large, constant esotropia following bilateral lateral rectus recessions for intermittent exotropia. Nine such patients were identified who warranted medical rectus recession. Seven were finally aligned within 6 prism dioptres after secondary surgery. Stereopsis measured 50 seconds or better in six of these patients and 200 seconds of arc in the seventh. Two patients had residual deviations: one child with 30 prism dioptres of residual esotropia had 400 arc seconds and the remaining patient, with 12 prism dioptres of exotropia and marked anisometropia, did not show stereopsis. Children with constant acquired esotropia for as long as two years may still have normal stereopsis after surgical alignment. The risk of losing binocularity because of a large overcorrection following exotropia surgery may be smaller than previously assumed.

Acute acquired comitant esotropia

Acute acquired comitant esotropia has been used to describe a dramatic onset of a relatively large angle of esotropia with diplopia and minimal refractive error. We describe six children aged 5 to 11 years who developed an acute non-accommodative esotropia with diplopia. Neurological examination, including CT scan, in each of these children gave negative results. We suggest that this is an unusual presentation of esotropia of undetermined aetiology. The diagnosis, clinical characteristics, and management are discussed.