A multi-stop time-of-flight spectrometer for the measurement of positron annihilation-induced electrons in coincidence with the Doppler-shifted annihilation gamma photon

In this study, we describe an advanced multi-functional, variable-energy positron beam system capable of measuring the energies of multiple "positron-induced" electrons in coincidence with the Doppler-shifted gamma photon resulting from the annihilation of the correlated positron. The measurements were carried out using the unique characteristics of the digital time-of-flight spectrometer and the gamma spectrometer available with the advanced positron beam system. These measurements have resulted in (i) the first digital time-of-flight spectrum of positron annihilation-induced Auger electrons generated using coincident signals from a high-purity Ge detector and a micro-channel plate, (ii) a two-dimensional array of the energy of Doppler-broadened annihilation gamma and the time-of-flight of positron-annihilation induced Auger electrons/secondary electrons measured in coincidence with the annihilation gamma photon, and (iii) the time-of-flight spectra of multiple secondary electrons ejected from a bilayer graphene surface as a result of the impact and/or annihilation of positrons. The novelty of the gamma-electron coincidence spectroscopy has been demonstrated by extracting the Doppler-broadened spectrum of gamma photons emitted due to the annihilation of positrons exclusively with 1s electrons of carbon. The width of the extracted Doppler-broadened gamma spectrum has been found to be consistent with the expected broadening of the annihilation gamma spectrum due to the momentum of the 1s electrons in carbon.

Time of flight spectrometer for background-free positron annihilation induced Auger electron spectroscopy

We describe a novel spectrometer designed for positron annihilation induced Auger electron spectroscopy employing a time-of-flight spectrometer. The spectrometer's new configuration enables us to implant monoenergetic positrons with kinetic energies as low as 1.5 eV on the sample while simultaneously allowing for the detection of electrons emitted from the sample surface at kinetic energies ranging from ∼500 eV to 0 eV. The spectrometer's unique characteristics made it possible to perform (a) first experiments demonstrating the direct transition of a positron from an unbound scattering state to a bound surface state and (b) the first experiments demonstrating that Auger electron spectra can be obtained down to 0 eV without the beam induced secondary electron background obscuring the low energy part of the spectra. Data are presented which show alternative means of estimating positron surface state binding energy and background-free Auger spectra.

Esophageal motility in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is characterized by eosinophilic infiltration of the esophagus and is a potential cause of dysphagia and food impaction, most commonly affecting young men. Esophageal manometry findings vary from normal motility to aperistalsis, simultaneous contractions, diffuse esophageal spasm, nutcracker esophagus or hypotonic lower esophageal sphincter (LES). It remains unclear whether esophageal dysmotility plays a significant role in the clinical symptoms of EoE.

AIM

Our aim is to review the pathogenesis, diagnosis, and effect of treatment on esophageal dysmotility in EoE.

METHODS

A literature search utilizing the PubMed database was performed using keywords: eosinophilic esophagitis, esophageal dysmotility, motility, manometry, impedance planimetry, barium esophagogram, endoscopic ultrasound, and dysphagia.

RESULTS

Fifteen studies, totaling 387 patients with eosinophilic esophagitis were identified as keeping in accordance with the aim of this study and included in this review. The occurrence of abnormal esophageal manometry was reported to be between 4 and 87% among patients with EoE. Esophageal motility studies have shown reduced distensibility, abnormal peristalsis, and hypotonicity of the LES in patients with EoE, which may also mimic other esophageal motility disorders such as achalasia or nutcracker esophagus. Studies have shown conflicting results regarding the presence of esophageal dysmotility and symptoms with some reports suggesting a higher rate of food impaction, while others report no correlation between motor function and dysphagia.

CONCLUSIONS

Motility dysfunction of the esophagus in EoE has not been well reported in the literature and studies have reported conflicting evidence regarding the clinical significance of dysmotility seen in EoE. The correlation between esophageal dysmotility and symptoms of EoE remains unclear. Larger studies are needed to investigate the incidence of esophageal dysmotility, clinical implications, and effect of treatment on patients with EoE.

Potent nonimmunosuppressive cyclophilin inhibitors with improved pharmaceutical properties and decreased transporter inhibition

Nonimmunosuppressive cyclophilin inhibitors have demonstrated efficacy for the treatment of hepatitis C infection (HCV). However, alisporivir, cyclosporin A, and most other cyclosporins are potent inhibitors of OATP1B1, MRP2, MDR1, and other important drug transporters. Reduction of the side chain hydrophobicity of the P4 residue preserves cyclophilin binding and antiviral potency while decreasing transporter inhibition. Representative inhibitor 33 (NIM258) is a less potent transporter inhibitor relative to previously described cyclosporins, retains anti-HCV activity in cell culture, and has an acceptable pharmacokinetic profile in rats and dogs. An X-ray structure of 33 bound to rat cyclophilin D is reported.

Development of Zn-ProPhenol-catalyzed asymmetric alkyne addition: synthesis of chiral propargylic alcohols

The development of a general and practical zinc-catalyzed enantioselective alkyne addition methodology is reported. The commercially available ProPhenol ligand (1) has facilitated the addition of a wide range of zinc alkynylides to aryl, aliphatic, and α,β-unsaturated aldehydes in high yield and enantioselectivity. New insights into the mechanism of this reaction have resulted in a significant reduction in reagent stoichiometry, enabling the use of precious alkynes and avoiding the use of excess dimethylzinc. The enantioenriched propargylic alcohols from this reaction serve as versatile synthetic intermediates and have enabled efficient syntheses of several complex natural products.

Thionium ion initiated medium-sized ring formation: the total synthesis of asteriscunolide D

The first synthesis of the biologically active humulene natural product asteriscunolide D has been accomplished in nine steps without the use of protecting groups. The challenging 11-membered ring was forged via a diastereoselective thionium ion initiated cyclization, which constitutes a formal aldol disconnection to form a strained macrocycle. A stereospecific thioether activation-elimination protocol was developed for selective E-olefin formation, thus providing access to the most biologically active asteriscunolide. The absolute stereochemical configuration was established by the Zn-ProPhenol catalyzed enantioselective addition of methyl propiolate to an aliphatic aldehyde to afford a γ-hydroxy propiolate as a handle for butenolide formation via Ru-catalyzed alkene-alkyne coupling.

Auger-mediated sticking of positrons to surfaces: evidence for a single-step transition from a scattering state to a surface image potential bound state

We present the observation of an efficient mechanism for positron sticking to surfaces termed here Auger-mediated sticking. In this process the energy associated with the positrons transition from an unbound scattering state to a bound image potential state is coupled to a valence electron which can then have sufficient energy to leave the surface. Compelling evidence for this mechanism is found in a narrow secondary electron peak observed at incident positron kinetic energies well below the electron work function.

The Enantioselective Addition of Alkyne Nucleophiles to Carbonyl Groups

Over the past decade, large strides have been achieved in the invention of methods for the direct enantioselective addition of alkynes and metal alkynylide nucleophiles into prochiral aldehydes, ketones, and imines. This review highlights and compares the available methods for these transformations.

Direct evidence for dynamic broadening of the energy spectra associated with the later steps of an Auger cascade

Auger cascade decay processes are of critical importance in x-ray-induced biological damage, chemical reactions, and desorption. Here, we report the first measurements of the isolated energy spectra of electrons emitted during the later steps of an Auger cascade process in a solid (MnO). The large widths and energy gains observed in cascade-induced Mn MVV Auger spectra (as compared to the spectra resulting from direct photoexcitation of the M core hole) provide strong evidence that valence holes created in previous cascade steps participate dynamically in later cascade steps.

Effect of vacuum annealing on the surface chemistry of electrodeposited copper(I) oxide layers as probed by positron annihilation induced auger electron spectroscopy

Vacuum anneal induced changes in the surface layers of electrodeposited copper(I) oxide (Cu2O) were probed by time-of-flight positron annihilation induced Auger electron spectroscopy (TOF-PAES) and by electron induced Auger electron spectroscopy (EAES). Large changes in the intensity of the Cu PAES intensity resulting from isochronal in situ vacuum anneals made at increasing temperatures indicated that, before thermal treatment, the surface was completely covered by a carbonaceous overlayer and that this layer was removed, starting at a temperature between 100 and 200 degrees C, to expose an increasing amount of Cu in the top layer as the anneal temperature was increased. The thickness of this overlayer was estimated to be approximately 4 A based on analysis of the EAES data, and its variation with the thermal anneal temperature was mapped. This study demonstrated the order-of-magnitude enhancement in the sensitivity of PAES to the topmost surface layer in Cu2O relative to the EAES counterpart; factors underlying this contrast are discussed. Finally, the implications of ultrathin carbon layers on semiconductor surfaces are discussed.

Catalytic Enantioselective Synthesis of Adociacetylene B

A catalytic enantioselective total synthesis of adociacetylene B (2) in five steps is reported. The efficiency of this synthesis was enabled by an asymmetric zinc alkynylation catalyzed by the proline-derived ligand (1).

Dinuclear Zn-catalyzed asymmetric alkynylation of unsaturated aldehydes

Our recent development of a proline-derived bimetallic catalyst has led to a number of efficient, catalytic, enantioselective transformations. Herein, we report a practical and general alkynylation of aromatic and alpha,beta-unsaturated aldehydes using our zinc catalyst system.

Giant Coster-Kronig transitions and intrinsic line shapes of the anomalous Pd M45VV Auger spectrum of Pd/Ag(100) dilute surface alloys

The Pd M4VV and M5VV Auger spectra of the 0.1 ML Pd/Ag(100) dilute surface alloy have been measured using Auger-photoelectron coincidence spectroscopy. The M4VV spectrum indicates that Pd 3d(3/2) core holes have a Coster-Kronig decay rate that is approximately 10 times that of Pd metal. Our calculations show that this giant enhancement arises from the local electronic structure of excited Pd atoms at the surface. Anomalous features in the Auger line shape are similar to those seen in dilute bulk PdAg alloys, and these features in the M5VV and M4VV lines are in good agreement with theoretical predictions.

Unilateral high myopia: optical components, associated factors, and visual outcomes

AIM

To elucidate the optical basis for unilateral high myopia and to identify the factors associated with its development.

METHODS

Medical records of 48 children (aged 4 months to 17 years; mean age 6.8 years) with unilateral high myopia (5 dioptres or more) seen consecutively by the author during a 15 year period were reviewed. 45 (94%) of the 48 patients had unilateral axial myopia.

RESULTS

The mean refractive difference between paired eyes was 9.4 (SD 3.6) dioptres and the more myopic eye was on average 3.3 (1.8) mm longer than the less myopic eye. All but three of the patients had an ocular disorder associated with reduced acuity, central nervous system abnormality, or family history of high myopia.

CONCLUSION

Clinical conditions associated with unilateral high myopia can be identified in the majority of patients and often account for the associated visual impairment.

Gamma spectra resulting from the annihilation of positrons with electrons in a single core level

The first gamma spectra associated with the annihilation of positrons with individual core levels (Cu 3p and Ag 4p) are presented. The spectra were obtained by measuring the energy of gamma rays time coincident with Auger electrons emitted as a result of positrons annihilating with a selected core level. Relativistic calculations show good agreement with experiment over a limited range of momenta. However, statistically significant differences indicate that the measurements can provide an impetus to new calculations of many body effects in positron-core electrons annihilation.

The infant who is visually unresponsive on a cortical basis

OBJECTIVE

To further explain cortical abnormalities in infants without visually guided behaviors with anatomically normal eyes by using a battery of objective visual tests and neuroimaging studies.

DESIGN

A cohort study.

PARTICIPANTS

Thirty-one infants with clear ocular media and normal fundi, who were visually unresponsive by clinical examination, and 31 control subjects.

METHODS

Full clinical examinations including Teller Acuity Cards (TAC) and developmental assessment. Infants with reduced acuities and/or developmental delay underwent pattern visual evoked potential (VEP) testing and brain neuroimaging studies. Eye movement recordings were done in individual infants.

MAIN OUTCOME MEASURES

Visual acuity, VEPs, eye movement recordings.

RESULTS

Infants were separated into two groups on the basis of being developmentally normal (DN) or developmentally delayed (DD). Fourteen DN infants had normal acuities for age and three of three infants had normal VEPs. On the basis of having normal visual function, these infants were considered to have visual inattention (VI). Sixteen DD infants had acuities ranging from normal to no visual orienting to the low vision TAC. All 16 DD infants had abnormal VEPs and abnormal neuroimaging studies (brain computed tomography, magnetic resonance imaging, or both) or microcephaly. On the basis of having structural and functional abnormalities of the brain, these infants were diagnosed as having cortical visual impairment (CVI). One additional infant with DD failed to orient to TACs but had a normal VEP and normal magnetic resonance imaging. In this infant and two infants with CVI the inability to "fix and follow" was attributed completely or partially to an oculomotor apraxia (OMA), which was confirmed by eye movement recordings.

CONCLUSIONS

The infant who is visually unresponsive on a cortical basis has either VI or CVI. Infants with OMA can also seem to be visually unresponsive. These disorders can be delineated in infancy on the basis of developmental status and a unique set of responses to visual acuity, VEPs, and oculomotor testing.

Episcleritis in childhood

OBJECTIVE

To describe the characteristics and systemic disease associations of episcleritis in childhood.

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Twelve children diagnosed with episcleritis between July 1981 and June 1998. METHODS/TESTING: Complete eye and systemic evaluations.

MAIN OUTCOME MEASURES

Characteristics of episcleritis and presence and nature of concurrent systemic disease.

RESULTS

The 12 children (10 boys and 2 girls) ranged in age from 13 months to 16 years. Five children had bilateral simple episcleritis, one had bilateral nodular episcleritis, and six had unilateral simple episcleritis. The eye examination was otherwise normal and recovery was uneventful in all cases. Six of the nine children older than 5 years of age had one of the following rheumatologic diseases: systemic lupus erythematosus, juvenile rheumatoid arthritis, spondyloarthropathy, inflammatory bowel disease, rheumatic fever, or polyarteritis nodosa. All three children younger than 5 years of age had simple episcleritis, an antecedent viral illness, and presented within 2 months of each other.

CONCLUSIONS

Episcleritis is a rare occurrence in childhood, especially in children younger than 5 years of age. In older children, it is frequently associated with rheumatologic disease.

Development of the spatio-chromatic visual evoked potential (VEP): a longitudinal study

Most prior visual evoked potential (VEP) research on the development of color vision has employed pattern-reversing stimuli that are not optimal for producing chromatic responses. We measured infant VEPs using low spatial frequency, onset-offset stimuli, modulated along the three axes of a cone-based color space (Derrington et al. [J. Physiol 1984;357, 241-265.]). Three color-normal infants were tested in a longitudinal design over the first postnatal year. One red/green color-deficient infant was also tested at 197 days. We found that VEP responses to S-axis (tritan) stimuli have their initial onset later than responses to red/green (L-M) or achromatic stimuli, and that developmental changes in VEP waveforms are more complex and longer lasting for chromatic than for achromatic stimuli. Possible mechanisms underlying these changes are discussed.

The pediatric sedation unit: a mechanism for pediatric sedation

OBJECTIVES

We have created a pediatric sedation unit (PSU) in response to the need for uniform, safe, and appropriately monitored sedation and/or analgesia for children undergoing invasive and noninvasive studies or procedures in a large tertiary care medical center. The operational characteristics of the PSU are described in this report, as is our clinical experience in the first 8 months of operation.

METHODS

A retrospective review of quality assurance data was performed. These data included patient demographics and chronic medical diagnoses, procedure, or study performed; sedative or analgesic medication given; complications (defined prospectively); and sedation and monitoring time. Patient-specific medical records related to the procedure and sedation were reviewed if a complication was noted in the quality assurance data.

RESULTS

Briefly, the PSU was staffed with an intensivist and pediatric intensive care unit nurses. Patients were admitted to the PSU and assessed medically for risk factors during sedation. Continuous heart rate, respiratory rate, and pulse oximetry monitoring were used, and blood pressure was determined every 5 minutes. After sedation and stabilization, with monitoring continued, the patient was transported to the site to undergo the procedure or study. The pediatric intensive care unit nurse remained with the patient at all times. All necessary emergency equipment was transported with the patient. After the procedure or study was completed, the patient was returned to the PSU for recovery to predetermined parameters. We were able to analyze 458 episodes of sedation for this review. Procedures and studies included radiologic examinations, cardiac catheterization, orthopedic manipulations, solid organ and bone marrow biopsy, gastrointestinal endoscopy, bronchoscopy, evoked potential measurements, and others. Patients were 2 weeks to 32 years of age. The average time from initiation of sedation to last dose of medication administered was 84 minutes. The average time from initiation of sedation to full recovery was 120 minutes. Sedative and analgesia medications use was not standardized; however, the majority of children needing sedation received propofol or midazolam. For patients requiring analgesia, ketamine or fentanyl was added. In 79 of 458 (12%) sedation episodes, complications were documented. Mild hypotension (4.4%), pulse oximetry <93% (2.6%), apnea (1.5%), and transient airway obstruction (1.3%) were the most common complications noted. Cancellation of 11 (2.4%) procedures was attributable to complications. No long-term morbidity or mortality was seen.

CONCLUSIONS

Many children require sedation or analgesia during procedures or studies. Safe sedation is best ensured by appropriate presedation risk assessment and with monitoring by a care provider trained in resuscitative measures who is not involved in performing the procedure itself. Uniformity of care in a large institution is a standard met by the creation of a centralized service, with active input from the department of anesthesiology. We present the PSU as a model for achieving these goals.

Ahomocysteinemia in molybdenum cofactor deficiency

We report an infant with molybdenum cofactor deficiency (MCD) and a unique clinical presentation of hemiplegia, hypotonia, dystonia, and bilateral basal ganglia changes. Biochemistry revealed absent serum homocysteine, low concentrations of plasma cystine, high levels of urinary S-sulfocysteine and sulfite, and high levels of oxypurines in serum and urine. The depletion of cysteine and cystine through reaction with sulfite suggests that other thiols and thiol-dependent proteins may be similarly depleted. Ahomocysteinemia may be a clue to the mechanism of cytotoxicity in MCD.

Methotrexate for resistant chronic uveitis in children with juvenile rheumatoid arthritis

We used low-dose methotrexate to treat seven children with juvenile rheumatoid arthritis-associated uveitis complicated by cataract and glaucoma or resistant to topical corticosteroid. The use of methotrexate decreased the severity of uveitis in six of seven patients and allowed for the discontinuation or reduction of corticosteroid drops.

Parental leave: comparing children's hospitals with Fortune 500 companies

OBJECTIVE

To identify parental leave policies and availability of support systems for new parents employed by children's hospitals and compare these benefits with those offered by Fortune 500 companies.

DESIGN

Telephone or facsimile survey of all (n=118) children's hospitals and pediatric medical centers in the National Association of Children's Hospitals and Related Institutions 1995 Directory of Members, and 118 geographically matched Fortune 500 companies. Policies for maternity and paternity leave, adoption benefits, and support services for new parents were compared.

RESULTS

Ninety-four children's hospitals (80%) and 82 Fortune 500 companies (69%) responded to the survey. No difference in duration of maternity (P>.30) or paternity (P=.12) leave was found. Sixty-two companies (77%) classified maternity leave as short-term disability while 47 hospitals (50%) classified it as sick time (P<.005). Classifying maternity leave as short-term disability generally gives better benefits to employees with short duration of service, whereas classifying maternity leave as sick time usually favors employees with longer employment. Companies provided more financial support for adoption expenses (P<.05), but there was no difference in duration of paid or unpaid leave for adoption (P=.14). Hospitals provided more on-site day care (69% vs 42%; P<.001) and better support systems for breast-feeding mothers (49% vs 24%; P<.002).

CONCLUSIONS

Children's hospitals do not offer better parental leave benefits than Fortune 500 companies; however, they offer better support systems for parents returning to work after the birth of a child.

Development of pattern visual evoked potentials: longitudinal measurements in human infants

PURPOSE

This experiment used longitudinal testing to trace the emergence of the major components of pattern visual evoked potentials (VEPs) in infants, using two paradigms: large-checkerboard pattern reversal and low spatial frequency pattern onset.

METHODS

Testing with both pattern-reversal and pattern-onset stimuli was performed on the same infants. Testing was conducted at weekly intervals during the first three postnatal months, and at intervals of 2 weeks to 1 month thereafter.

RESULTS

The pattern-reversal and early pattern-onset responses recorded within individual subjects showed remarkably systematic developmental sequences. The broad, positive component seen at 200 to 250 ms in infants could be traced readily through the developmental sequence, to become the more sharply tuned positive component seen at about 100 ms in adults. Responses to low spatial frequency pattern onsets in infants were larger and more reliable than those in adults. The late components of the pattern-onset response, generally attributed to pattern offset, emerged later and with more complex changes. In all cases, response amplitude was much more variable than response latency, both within and between subjects.

CONCLUSIONS

Frequent VEP recording in a longitudinal design can reveal systematic and detailed transitions of wave-form during development.

Clinical neurological evaluation

The importance of the neurological evaluation for PLDD procedures is discussed. Elements of the basic examination are outlined and the reason for specific methods of testing are offered. The physician should pay attention to patient complaints, mechanical signs, and patient capabilities.

Visual outcomes of macular retinoblastoma after external beam radiation therapy

PURPOSE

To determine the risk factors that influence the visual outcomes of patients with macular retinoblastoma who are treated with radiation therapy.

METHODS

The medical records of all patients with macular retinoblastoma treated with radiation therapy between 1980 and 1990 were reviewed. Ten patients were entered into the study. Features analyzed included patient age, laterality of eye involvement, location and size of macular tumor(s) at the time of diagnosis, treatment course, and most recent visual acuity.

FINDINGS

Ten of 11 eyes (10 patients) were successfully treated with external beam radiation. Eight patients obtained visual acuities ranging from 20/25 to 20/100; two patients had visual acuities of 20/200 or less. The best visual acuities were noted in patients whose tumor(s) did not involve the fovea and were relatively small. The worse visual acuities were noted in patients with binocular vision whose tumors invaded the fovea and were larger in size. In two of three patients in whom both eyes were retained, superimposed amblyopia developed in the eye with macular retinoblastoma.

CONCLUSION

The authors' findings indicate that most patients with macular retinoblastoma who are treated with external beam radiation have favorable visual outcomes, but final visual acuity depends on the size of the tumor and involvement of the fovea. Patients in whom both eyes are retained are predisposed to further visual loss from amblyopia.

The swollen and droopy eyelid. Signs of systemic disease

Swollen and droopy eyelids are obvious ocular findings, unlike many ocular conditions that require the use of special equipment to observe. Neither of these findings is a specific diagnosis but rather each is evidence of localized disease and often is a sign of underlying systemic disorder. Therefore, it is important for the clinician evaluating the child with a swollen or droopy lid to have a working knowledge of these diagnostic possibilities. In this article the author presents the various causes of the swollen and droopy eyelid, focus on the most relevant clinical characteristics, and emphasize systemic associations.

Quantification of monocular optokinetic nystagmus asymmetries and motion perception with motion-nulling techniques

When tested monocularly, strabismic and amblyopic subjects often show asymmetries of optokinetic nystagmus (OKN), with OKN being more readily elicited by temporal-to-nasal than by nasal-to-temporal stimulus motion. We tested five visually normal subjects and ten strabismic and/or amblyopic subjects by use of motion-nulling stimuli, which consisted of superimposed temporal-to-nasal and nasal-to-temporal sinusoidal-grating components with a summed contrast of 100%. Both the direction of OKN and the subject's perceived direction of motion (PDM) were tested. Most normal subjects showed symmetrical OKN and PDM, but a rightward OKN bias was observed in one of the visually normal subjects. Temporal-to-nasal eye-movement biases were seen in most strabismic and amblyopic subjects, whereas PDM biases were smaller and less frequent. The primary purpose of this study was to demonstrate the feasibility of quantifying OKN and PDM asymmetries in a diverse group of visually abnormal adults by use of the motion-nulling technique. Application of this technique to larger and more homogeneous clinical populations may contribute to the continued differentiation and characterization of variants of the visual disorders associated with strabismus and amblyopia and with other defects of binocular vision.

Ankyloblepharon filiforme adnatum

We treated 4 infants with ankyloblepharon filiforme adnatum (AFA), an uncommon anomaly in which the apposing eyelid margins are connected by abnormal tissue strands. One infant had AFA alone, one had Hay-Wells syndrome, characterized by ectodermal dysplasia, and the other 2 had chromosome abnormalities, trisomy 18, and complex chromosome rearrangement, with visceral malformations. Despite heterogeneity and phenotypic variability, these developmental abnormalities shared (1) involvement of tissues growing in apposition and (2) temporal overlap of their occurrence. This suggests a common defect in the mechanism(s) that regulate tissue fusion at multiple sites during development.

Axial myopia in eyes with optic nerve hypoplasia

Given that abnormal visual experience during post natal development interferes with emmetropization, we proposed that eyes with hypoplastic optic nerves were predisposed to the development of refractive errors. Six of 14 patients with unilateral optic nerve hypoplasia and 5 of 22 patients with bilateral involvement had at least 4 D of myopia. Nine of the 11 patients with asymmetric bilateral involvement had relative myopia in the eye with the more abnormal optic nerve; none of the patients with symmetric bilateral involvement had a significant interocular refractive difference. Analysis of axial length measurements obtained in 10 of the 11 patients with high myopia showed a significant increase in total axial length. The presumed normal eye of patients with unilateral involvement was significantly smaller than the mean value for age-adjusted normals. We suspect that visual input to the central nervous system is one of the feedback signals involved in the regulation of ocular growth.

Simple microphthalmos

Simple microphthalmos was diagnosed in 22 patients on the basis of a normal-appearing eye and a total axial length at least 2 SDs below the mean for age. Anterior segment length was normal in most patients while posterior segment length was at least 2 SDs below the mean in all patients, indicating that disproportionate reduction in posterior segment length accounted for the microphthalmos. The normal values for total axial length, anterior segment length, and posterior segment length were determined from the analysis of axial length measurements obtained from age-similar controls. Ten patients had isolated microphthalmos. One of them was diagnosed as having nanophthalmos on the basis of microcornea, total axial length less than 18 mm, and absence of systemic disease. Twelve patients had associated systemic disorders, such as fetal alcohol syndrome, myotonic dystrophy, and achondroplasia, which implicated decreased size of the optic cup, altered vitreous proteoglycans, low intraocular pressure, and abnormal release of growth factors in the pathogenesis of microphthalmos.

Complex microphthalmos

Forty patients were diagnosed as having complex microphthalmos on the basis of a malformed globe with a total axial length measurement at least 2 SDs below the mean for age-similar controls. Three had anterior segment dysgenesis; 4, congenital lens abnormalities; 14, chorioretinal colobomas; 12, persistent hyperplastic primary vitreous; 4, retinal dysplasia; and 3, complex malformations due to ipsilateral facial malformations. Measurements of total axial length indicated that complex microphthalmos was congenital and that postnatal growth of the malformed eye was similar to that of normal eyes. In most patients the anterior segment length was normal, while in all patients the posterior segment length was at least 2 SDs below the mean. Corneal diameter correlated significantly with total axial length (r2 = .57) and decreased linearly as total axial length decreased. In most patients in whom measurements were obtained, the lens and corneal power were increased, thereby compensating for decreased total axial length. We propose that inadequate production of secondary vitreous is the cause of the microphthalmos, given that the posterior segment was disproportionately reduced in size and the secondary vitreous is its predominant component. Evidence that each of the various ocular malformations can influence the production of secondary vitreous is presented.

Blue cone monochromatism

Blue cone monochromatism (BCM) is a subtype of achromatopsia in which the blue cone mechanism predominates. Each of the four patients in this study had BCM proven by their having peak spectral sensitivities in the blue region of the visible spectrum (near 440 nm). Clinically, the diagnosis was suspected because of x-linked inheritance, the presence of acuities better than 20/200 in two patients and myopia ranging from -1.75 to -15.00 diopters in three patients. Congenital nystagmus was the presenting sign in three of the four patients. Examination of the fundi was uniformly normal. The distinctive spectral properties of BCM were demonstrated by the American Optical H-R-R and the Panel D-15 tests. All affected patients correctly identified three of the four blue-yellow plates and a variable number of the red-green plates in the American Optical H-R-R test. The study patients consistently made errors oriented along the protan and deutan axes but they made none along the tritan axis. The authors conclude that the results of these two color discrimination tests are useful in diagnosing BCM.

Neuroretinitis in childhood

We report the clinical features and results of laboratory testing of seven children with neuroretinitis, diagnosed on the basis of reduced visual acuity, relative afferent pupillary defect, and distinctive appearance of the fundi. Disc swelling was segmental in five patients with unilateral disease and diffuse in two patients with bilateral disease. Retinal infiltrates were transiently present in two patients. Swelling of the optic disc and peripapillary retina, along with the inflammatory vitritis resolved by 2 to 6 weeks but macular exudates persisted for 3 to 12 months. Two patients developed optic atrophy with permanent visual loss and two patients had visual acuity reduction detected only under low contrast conditions. Cat-scratch disease was implicated as the cause of the neuroretinitis in two patients; the etiology of the remaining cases was not established.

Adrenal suppression after corticosteroid injection of periocular hemangiomas

Two infants with symptomatic periocular hemangiomas received 1-ml intralesional injections of a 50:50 mixture of triamcinolone acetonide (40 mg/ml) and betamethasone (8 mg/ml). Both developed adrenal suppression as evidenced by the immediate depression of their serum cortisol and adrenocorticotrophic hormone levels. One patient remained adrenal suppressed for five months and, concurrently, her growth rate and weight dropped from normal to below the fifth percentile. Adrenal suppression should be added to the growing list of complications caused by the corticosteroid injection of periocular hemangiomas.

Visual sensory disorders in congenital nystagmus

Congenital nystagmus (CN) is a common disorder indicative of a primary disturbance of the ocular motor or visual sensory systems. The authors prospectively evaluated 81 patients with CN, structurally normal eyes, and minimal or no abnormalities of the optic nerve, macula, and retinal pigment epithelium (RPE). Seventy-four (91%) patients were found to have a disorder of the visual sensory system. Thirty-four patients had albinism, 37 had a congenital or early onset disorder of the retinal photoreceptors, and 3 had abnormalities of the optic nerve. The remaining seven (9%) patients had motor CN. Most patients presenting with CN have visual loss and should be evaluated for an underlying disorder of the visual sensory system.

Primary and secondary orbital teratomas

Two patients with primary teratomas of the orbit and a third patient with a teratoma invading the orbit from the maxillary sinus are presented. The clinical presentation of each patient was spectacular. In the primary teratomas, the globe was displaced out of the orbit by the attached tumor, causing extreme proptosis. Computed tomography was virtually diagnostic, showing a variegated orbital mass with solid and cystic components. Histologic examination showed multiple tissues derived from two or three germinal layers. The surgical removal of the tumors and reasons for the poor visual outcome are discussed. The appearance of teratomas in the orbit and other cephalic structures appears to arise from the survival and proliferation of germ cells deposited there during embryogenesis.