Optic nerve hypoplasia in children

Association of prepregnancy body mass index and gestational weight gain on severity of optic nerve hypoplasia

BACKGROUND

Optic nerve hypoplasia (ONH) is a birth defect of unknown etiology and a leading cause of visual impairment in developed countries. Recent studies suggest that factors of deprivation and exposures of poor nutritional status, such as lower gestational weight gain (GWG), may be associated with increased risk of ONH. The present study describes the prenatal features of mothers of ONH cases, including prepregnancy BMI and GWG, and the associations with clinical features of disease severity.

METHODS

Retrospective study of prenatal records for cases of ONH enrolled in a research registry. Prepregnancy BMI and GWG were compared to maternal characteristics and clinical findings of ONH severity including bilaterality, hypopituitarism, and neuroradiographic abnormalities.

RESULTS

Compared to population-based normative data of births in the United States, mothers of ONH cases (n = 55) were younger (23.3 vs. 25.8 years; p = 0.03), with higher incidence of inadequate GWG (34.0% vs. 20.4%; p = 0.03) predominantly in the first and second trimesters. The presence of major brain malformations was associated with younger maternal age (21.6 [IQR 19.4, 24.7] vs. 24.9 years [IQR 22.1, 28.5] [p = 0.02]), primiparity (44.1% vs. 13.3%; p = 0.05) and decreased prepregnancy BMI (20.9 kg/m2 [19, 22.5] vs. 25.5 kg/m2 [21.3, 28.2]; p < 0.01).

CONCLUSION

Decreased prepregnancy BMI and inadequate GWG correlated with clinical features of ONH severity, specifically bilateral disease and presence of major brain malformations.

Comparative study on optic disc features of premature infants and full-term newborns

Background

To study optic disc features of premature infants and compare to that of term infants to explore the pattern and features of newborn optic disc development and provide the basis for the diagnosis of newborn optic disc disease.

Methods

This was a prospective clinical research. Newborns underwent newborn fundus disease screening from January 1st, 2016 to October 31st, 2016 in the neonatal ward of Ruian City Maternal and Child Health Hospital were selected. RetCam 3 Version6.1.25.0 Wide-Field Digital Pediatric Retinal Imaging System developed by Clarity Medical Systems, Inc was adopted to conduct fundus examination on both eyes, 130 degree wide-angle lens was used to film the images centering optic disc.

Results

For both premature infants and full-term newborns, vertical diameter of the optic disc to lateral diameter of the optic disc ratio was > 1, and the shape of the optic disc was a vertical oval. The difference of each optic disc parameter between premature infants and full-term newborns was not statistically significant (P > 0.05). There’s a difference of constitution of sclerotic ring type on optic disc between premature infants and full-term newborns. Among which, the proportion of single ring type and double ring type in premature infants was higher than that in full-term newborns (P < 0.05). The proportion of no ring type in full-term newborns was higher than that in premature infants (P < 0.05). The proportion of mixed type had no significant difference (P > 0.05) between premature infants and full-term newborns.

Conclusions

We found that The proportion of mature types (single ring type and double ring type) in full-term newborns was higher than that in premature infants. While there’s no statistical difference of the proportion of mixed types between premature infants and full-term newborns. Double ring type was a normal stage of the development of optic disc.

Transcriptome analysis of the zebrafish atoh7-/- Mutant, lakritz, highlights Atoh7-dependent genetic networks with potential implications for human eye diseases

Expression of the bHLH transcription protein Atoh7 is a crucial factor conferring competence to retinal progenitor cells for the development of retinal ganglion cells. Several studies have emerged establishing ATOH7 as a retinal disease gene. Remarkably, such studies uncovered ATOH7 variants associated with global eye defects including optic nerve hypoplasia, microphthalmia, retinal vascular disorders, and glaucoma. The complex genetic networks and cellular decisions arising downstream of atoh7 expression, and how their dysregulation cause development of such disease traits remains unknown. To begin to understand such Atoh7-dependent events in vivo, we performed transcriptome analysis of wild-type and atoh7 mutant (lakritz) zebrafish embryos at the onset of retinal ganglion cell differentiation. We investigated in silico interplays of atoh7 and other disease-related genes and pathways. By network reconstruction analysis of differentially expressed genes, we identified gene clusters enriched in retinal development, cell cycle, chromatin remodeling, stress response, and Wnt pathways. By weighted gene coexpression network, we identified coexpression modules affected by the mutation and enriched in retina development genes tightly connected to atoh7. We established the groundwork whereby Atoh7-linked cellular and molecular processes can be investigated in the dynamic multi-tissue environment of the developing normal and diseased vertebrate eye.

Electroretinograms in idiopathic infantile nystagmus, optic nerve hypoplasia and albinism

PURPOSE

To study electroretinograms in infantile nystagmus syndrome associated with idiopathic infantile nystagmus, optic nerve hypoplasia, and albinism.

METHODS

A total of 30 children with idiopathic infantile nystagmus, 18 with optic nerve hypoplasia, and 18 with albinism were studied. Three electroretinogram protocols were applied according to child's age: 58 (mean: 2.0 years) were recorded with skin electrode to Great Ormond Street Hospital protocol, 11 (mean: 5.3 years) with skin electrode to International Society for Clinical Electrophysiology of Vision protocol, and 7 children (mean: 12.2 years) with HK electrode to International Society for Clinical Electrophysiology of Vision protocol. The electroretinograms were compared to those of age-matched controls.

RESULTS

Electroretinogram waveforms in idiopathic infantile nystagmus, optic nerve hypoplasia, and albinism were comparable to controls in all protocols. Electroretinogram amplitudes in idiopathic infantile nystagmus group showed increased white scotopic and photopic electroretinograms in 26 children (skin electrode to Great Ormond Street Hospital protocol), no difference to the controls in 3 children (skin electrode to International Society for Clinical Electrophysiology of Vision protocol), and increased rod electroretinogram in 3 children (HK electrode to International Society for Clinical Electrophysiology of Vision protocol). Optic nerve hypoplasia group showed increased white scotopic, photopic, and blue electroretinograms in 15 children (skin electrode to Great Ormond Street Hospital protocol); increased 30-Hz electroretinogram in 3 children (HK electrode to International Society for Clinical Electrophysiology of Vision protocol); and reduced combined rod-cone, cone, and 30-Hz electroretinograms in 3 children (skin electrode to International Society for Clinical Electrophysiology of Vision protocol). Albinism group showed increased white scotopic, photopic, and 30-Hz electroretinograms in 17 children (skin electrode to Great Ormond Street Hospital protocol), while it showed reduced cone and 30-Hz electroretinograms in 5 children (skin electrode to International Society for Clinical Electrophysiology of Vision protocol). Implicit times were shorter in albinism.

CONCLUSION

Electroretinogram waveforms in idiopathic infantile nystagmus, optic nerve hypoplasia, and albinism were normal with mostly increased electroretinograms, while reduced electroretinograms did not show a specific pattern as in early-onset retinal dystrophies.

Optic Nerve Hypoplasia in Fetal Alcohol Syndrome: An Update

Optic nerve hypoplasia was detected in up to one half of a group of Swedish children born to alcoholic mothers. Using an experimental model of pre- and postnatal alcohol exposure in rats fed a liquid diet, reduced optic nerve size from gestational day 21 (294 ± 26×102 μm2 vs 502 ± 16×102 μm2; n=6; p≤0.001) to later in development was observed as a result of the daily mean blood alcohol levels achieved in dams and their offspring. Altered glial cells and degenerating and atrophic optic axons, myelin sheaths and ganglion cells were frequent in the alcohol-exposed optic nerves.

Smaller optic nerve (1,918 ± 61×102 μm2 vs 2.195 ± 40×102 μm2; n=4; p≤0.001), reduced gaglion cell and axonal densities, and ultrastructural damage to the macroglial cells and myelin sheaths were also detected in the treated group. All these changes remained in the retina and optic nerve of the oldest rats, as a consequence of the long-lasting effects of prenatal alcohol exposure. In summary, alcohol as a major teratogenic agent may induce dysmorphogenesis and irremediable damage to the retina and optic nerve, which frequently manifests itself as hypoplastic optic nerve.

Congenital anomalies of the optic disc: insights from optical coherence tomography imaging

PURPOSE OF REVIEW

Congenital anomalies of the optic nerve are rare but significant causes of visual dysfunction in children and adults. Accurate diagnosis is dependent on a thorough funduscopic examination, but can be enhanced by imaging information garnered from optical coherence tomography (OCT). We review common congenital optic nerve anomalies, including optic disc pit, optic nerve coloboma, morning glory disc anomaly, and hypoplasia of the optic nerve, review their systemic associations, and discuss insights from OCT imaging.

RECENT FINDINGS

Optic disc pits are a result of a defect in the lamina cribrosa and abnormal vitreomacular adhesions have been shown to cause maculopathy. In patients with optic nerve colobomas, OCT can be instrumental in diagnosing choroidal neovascularization, a rare but visually devastating complication. The pathogenesis of morning glory disc anomaly has been more clearly elucidated by OCT as occurring from a secondary postnatal mesenchymal abnormality rather than only the initial neuroectodermal dysgenesis of the terminal optic stalk in isolation. OCT studies of optic nerve hypoplasia have demonstrated significant thinning of the inner and outer retinal layers of the perifoveal region and thicker layers in the fovea itself, resulting in a foveal hypoplasia-like pathology, that is, significantly correlated to poorer visual outcomes.

SUMMARY

OCT provides detailed in-vivo analysis of these anatomic anomalies and their resulting pathologies, shedding new insights on the pathogenesis, diagnosis, and potential visual outcomes of these conditions in children. Further study employing OCT to elucidate structure-function relationships of congenital optic nerve anomalies will help expand the role of OCT in clinical practice related to diagnosis, prognosis, and management of these entities.

VEP analysis methods in children with optic nerve hypoplasia: relationship to visual acuity and optic disc diameter

PURPOSE

Assessing vision in young children with optic nerve hypoplasia (ONH) is challenging due to multi-directional infantile nystagmus, the range of optic nerve loss, and cognitive delay. This study examined visual evoked potential (VEP) responses and averaging techniques in children with ONH. The assumption is that EEG epochs with inconsistent temporal phase would be associated with nystagmus, signal reduction due to axon loss, and visual inattention.

METHODS

A retrospective chart review was performed on 44 children (average age 2.2 years; SD 1.9). Optic disc diameter was estimated by ophthalmoscopy. Visual function was measured under binocular viewing and then compared to the eye with the larger optic disc to exclude secondary amblyopia. Visual acuity was measured by Teller cards or by recognition optotypes, and both measures were converted into log minimum angle of resolution (logMAR). VEPs were recorded to onset/offset of horizontal gratings and to reversing checkerboards. Signal-to-noise ratios (SNRs) were estimated from phase consistency across epochs in the Fourier domain. VEPs were also averaged after (1) correction of epochs for phase shifts across a limited bandwidth, or (2) selection of only epochs showing phase consistency.

RESULTS

Optic disc diameter, logMAR, VEP amplitudes, and VEP SNR were all significantly inter-correlated. Optic disc diameter correlated best with VEP SNR (Spearman rho = 0.82; p < 0.001). Age-corrected logMAR correlated with optic disc diameter and VEP SNR (Spearman rho = -0.695 and 0.70, respectively; p < 0.001). VEP latency poorly correlated with optic disc diameter or logMAR. Correction of phase shifts or selection of epochs based on phase consistency significantly increased VEP amplitude and SNR for children with optic disc diameters <1000 microns. Correction of phase inconsistency did not improve the correlation of VEP parameters with optic disc diameter or with logMAR.

CONCLUSIONS

In ONH, the size of the optic nerve is correlated with VEP SNR and logMAR. The results imply a direct relationship between the reduction in optic nerve axons and generalized reduction in visual function. Our calculation of VEP SNR provides objective assessment of optic nerve function that is independent of subjective scoring of VEP peaks.

OCT in a Myelinated Retinal Nerve Fiber Syndrome with Reduced Vision

PURPOSE

The prognosis of success with vision therapy in refractive "amblyopia" associated with the syndrome of myelinated nerve fibers (MRNF), optic disc hypoplasia, and myopia is reported to be poorer than that of anisomyopic amblyopia without these features. The reason for the poorer prognosis has not been well understood. The purpose of this study was to perform spectral domain (SD) ocular coherence tomography (OCT) to determine if there is a structural etiology that may explain the poorer prognosis.

CASE REPORTS

Case 1 was a 12-year-old male patient with anisometropic "amblyopia" in the right eye, MRNF denser superiorly, a hypoplastic disc, and a myopic fundus with a flat intact macula. The OCT demonstrated an attenuated photoreceptor integrity line (PIL) in the macula. Case 2 was a 10-year-old male patient with a constant left esotropia, MRNF denser superiorly, a hypoplastic disc, and a myopic fundus with a flat intact macula. The OCT demonstrated an absent PIL. Case 3 was a 58-year-old female patient with a history of diabetic retinopathy OU, long-standing reduced vision in the right eye, MRNF denser superiorly, optic nerve hypoplasia, and a myopic fundus with an intact macula. The OCT demonstrated an absent PIL in the macula.

CONCLUSIONS

This case series identifies three patients with the syndrome of MRNF, optic nerve hypoplasia, and anisomyopia in one eye with reduced vision and reports OCT findings using SD-OCT systems. All three patients demonstrated an absence or attenuation of the photoreceptor integrity line (PIL) in the macula in the affected eye. To our knowledge, there is no known association between this syndrome and abnormality of the PIL reported in the literature. Patients with this syndrome may have a guarded prognosis in the success of vision therapy.

Neuroimaging and clinical features of patients with optic nerve hypoplasia in Taiwan

PURPOSE

To investigate the clinical and neuroradiographic features of Chinese patients with optic nerve hypoplasia (ONH).

METHODS

This was a retrospective case series study. The medical records and magnetic resonance imaging (MRI) studies of patients diagnosed with ONH from September 2001 to December 2013 in the neuro-ophthalmology clinic of Taipei Veterans General Hospital were reviewed.

RESULTS

A total of eight eyes of five patients with ONH were enrolled in this study (1 male, 4 females). The mean age at diagnosis was 14.5 ± 12.0 years (range 0.25-30 years). Ocular examination revealed approximately half of the eyes had tortuous retinal vessels. In MRI studies, all patients had midline brain abnormalities including ectopic posterior pituitary gland (60%), agenesis of septum pellucidum (20%), and Rathke's cleft cyst (20%). Two patients had endocrinopathies-one suffered from hypopituitarism and the other had hyperprolactinemia. Both of them showed ocular findings of tortuous retinal vessels.

CONCLUSION

A high prevalence of midline brain abnormalities was noted in ONH patients of Chinese ethnicity. The presence of tortuous retinal vessels in patients with a midline brain anomaly may indicate the occurrence of endocrinopathy.

Optical coherence tomographic findings in optic nerve hypoplasia

We investigated a case of unilateral optic nerve hypoplasia using spectral domain optical coherence tomography (SDOCT). Optical coherence tomography was done on both eyes using 5-line Raster scan for the fovea to analyze the retinal nerve fiber layer thickness, inner retinal layer thickness, outer retinal layer thickness, and optic disc cube scan for the disc. Retinal nerve fiber layer thickness, inner retinal layer thickness, and outer retinal layer thickness were manually measured at 21-points of each five lines, and results were compared between both eyes. Retinal nerve fiber layer thickness and inner retinal layer thickness of optic nerve hypoplasia were significantly thinner than the opposite eye, but there was no significant difference in the thickness of the outer retinal layer between both eyes.

Optic nerve hypoplasia

Optic nerve hypoplasia (ONH) is a congenital anomaly of the optic disc that might result in moderate to severe vision loss in children. With a vast number of cases now being reported, the rarity of ONH is obviously now refuted. The major aspects of ophthalmic evaluation of an infant with possible ONH are visual assessment, fundus examination, and visual electrophysiology. Characteristically, the disc is small, there is a peripapillary double-ring sign, vascular tortuosity, and thinning of the nerve fiber layer. A patient with ONH should be assessed for presence of neurologic, radiologic, and endocrine associations. There may be maternal associations like premature births, fetal alcohol syndrome, maternal diabetes. Systemic associations in the child include endocrine abnormalities, developmental delay, cerebral palsy, and seizures. Besides the hypoplastic optic nerve and chiasm, neuroimaging shows abnormalities in ventricles or white- or gray-matter development, septo-optic dysplasia, hydrocephalus, and corpus callosum abnormalities. There is a greater incidence of clinical neurologic abnormalities in patients with bilateral ONH (65%) than patients with unilateral ONH. We present a review on the available literature on the same to urge caution in our clinical practice when dealing with patients with ONH. Fundus photography, ocular coherence tomography, visual field testing, color vision evaluation, neuroimaging, endocrinology consultation with or without genetic testing are helpful in the diagnosis and management of ONH. (Method of search: MEDLINE, PUBMED).

Absence of age-related optic disk changes in young children with optic nerve hypoplasia

PURPOSE

To determine whether the ratio of optic disk diameter to disk-to-macula distance (DD/DM) in children with optic nerve hypoplasia (ONH) changes over time.

PATIENTS AND METHODS

Fifteen subjects (29 eyes) enrolled in a prospective registry study on ONH had fundus photography performed under the age of 24 months and again at 60 months. Using the ratio of the DD/DM method, the relative size of the optic disk was assessed twice for each photo by one masked expert examiner to determine whether any change in relative disk size occurred over time.

RESULTS

There was no change in relative optic disk size between initial and final fundus photographs. The average (± SD) age at the time of initial and final fundus photography was, respectively, 11.6 ± 5.2 months and 60.6 ± 1.3 months. Strong concordance was noted between the average DD/DM of the initial and the final photographs (ρ=0.939; 95% CI: 0.893, 0.981). There was negligible difference between the individual time point measurements (-0.011 ± 0.03) (95% LOA: -0.07, 0.04).

CONCLUSION

There were no clinically significant changes in relative optic disk size over time in children with ONH; thus, DD/DM measurements need not be adjusted by age beyond 1 year in children with this disorder.

Incidence and associated endocrine and neurologic abnormalities of optic nerve hypoplasia

IMPORTANCE

Optic nerve hypoplasia (ONH) is an increasingly recognized cause of congenital blindness in children; however, there is significant discord regarding its incidence and the rate of associated conditions.

OBJECTIVE

To determine the incidence of ONH and the rate of associated endocrine, neurologic, and developmental abnormalities among a population-based cohort of pediatric patients.

DESIGN

Retrospective, population-based study.

SETTING

Olmsted County, Minnesota (95.7% white in 1990).

PARTICIPANTS

All pediatric residents (aged <19 years) of Olmstead County, diagnosed as having ONH from January 1, 1984, through December 31, 2008.

MAIN OUTCOMES AND MEASURES

Incidence of ONH and the rate of associated endocrine, neurologic, and developmental abnormalities.

RESULTS

Optic nerve hypoplasia was diagnosed in 19 pediatric patients during the 25-year study period, for an annual incidence of 2.4 (95% CI, 1.2-3.5) per 100,000 residents younger than 19 years or 1 in 2287 live births. The mean age at diagnosis was 2.1 years, and 10 (53%) patients were male. Commonly associated perinatal conditions included primiparity in 8 patients (42%), premature birth in 6 (32%), and maternal diabetes mellitus in 3 (16%). Of the 19 study patients, 16 (84%) had bilateral involvement at initial examination, 9 (47%) had decreased visual acuity, 8 (42%) had strabismus, and 5 (26%) had nystagmus. Systemic conditions included developmental delay in 12 (63%), neurologic deficits in 10 (53%), and endocrine dysfunction in 5 (26%).

CONCLUSIONS AND RELEVANCE

This population-based study demonstrated an incidence of ONH of 1 in 2287 live births. More than half of the patients had developmental and neurologic deficits, and one-fourth had a diagnosis of endocrine dysfunction.

Clinical distinction between nasal optic disc hypoplasia (NOH) and glaucoma with NOH-like temporal visual field defects

Purpose:

To report on the clinically important differences between nasal optic hypoplasia (NOH) and glaucoma with NOH-like temporal visual field defect (VFD).

Method:

Five NOH (four bilateral and one unilateral) patients, three unilateral NOH patients with glaucoma, and two glaucoma patients with NOH-like temporal VFD were clinically characterized. Superior segmental optic nerve hypoplasia was also associated with glaucoma in one eye of a bilateral NOH case and the NOH eye of a unilateral NOH patient. Ocular manifestations including refractive errors, size, and appearances of the optic discs, retinal nerve fiber thickness (NFLT) ascertained by optical coherence tomography (OCT), and VFD were examined.

Results:

Ophthalmic examinations revealing NOH showed high myopia at more than −5.0D, a small disc with nasal double-ring appearance, significantly decreased NFLT by OCT, and retinal nerve fiber layer defect in the corresponding nasal sector. Stationary temporal VFD varied from a slight depression of the peripheral isopters to wide sector defects. In contrast, two glaucoma patients with NOH-like temporal VFD showed several different clinical features, including mild myopia less than −5D, a normal size with glaucomatous disc cupping; a slight decrease in nasal NFLT and progression of temporal and other glaucomatous VFD.

Conclusion:

Careful evaluation of optic disc appearance and measurement of NFLT using OCT may help to distinguish between NOH and glaucoma with NOH-like temporal VFD.

Bilateral Duane retraction syndrome with optic nerve hypoplasia

The authors report a unique case of a child with the infrequent association of bilateral Duane retraction syndrome with underdevelopment of the anterior visual pathway. Both conditions were caused presumably due to a common disturbance of neuronal development during the second month of embryogenesis.

Unilateral megalopapilla and contralateral optic nerve hypoplasia: a case report and review of the literature

We report the incidental finding of megalopapilla in the contralateral eye of a 10-year-old black child with optic nerve hypoplasia. Megalopapilla is a rare entity characterized by an enlarged optic disk without other morphologic abnormalities except for an enlarged cup/disk ratio. To the best of our knowledge, the concurrence of megalopapilla and optic nerve hypoplasia in the same individual has not been reported previously.

Unilateral optic nerve aplasia associated with rudimental retinal vasculature

Optic nerve aplasia (ONA) is a rare congenital malformation characterized by absence of optic disk, optic nerve, retinal ganglion cells, and central retina vessels. It is frequently associated with other ocular and central nervous system anomalies. In this paper, we describe a case of ONA associated with microphthalmos and a rudimental retinal vasculature in an otherwise healthy infant.

Syndrome of myelinated retinal nerve fibers, myopia, and amblyopia: a review

Myelinated retinal nerve fibers are developmental anomalies that are present in approximately 1% of all eyes. They may be associated with ipsilateral high myopia and amblyopia, and also may occur in association with various ocular and systemic abnormalities. Lesions may be congenital or acquired, static or dynamic, and can regress in the setting of several described conditions. The pathogenesis is thought to be due to the presence of ectopic oligodendrocyte-like cells in the retina as a result of a development or acquired insult. Visual acuity is typically poor to begin with, and the improvement of visual function in patients undergoing occlusion therapy has been, in general, limited. We discuss a series of 11 patients seen at the Cole Eye Institute with the condition of myelinated retinal nerve fibers, myopia, and amblyopia and describe the clinical characteristics. Three patients also had optic nerve dysplasia and a discussion of the literature related to this association was also performed.

Association of optic nerve hypoplasia with mitochondrial cytopathies

Ocular complications are common in the mitochondrial cytopathies and include optic atrophy and retinal degeneration. We retrospectively reviewed 80 patients with nonsyndromic mitochondrial cytopathies (ie, not Kearns-Sayre syndrome, myoclonus epilepsy associated with ragged red fibers [MERRF], mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes [MELAS], neuropathy ataxia and retinitis pigmentosa, Leigh disease, maternally inherited diabetes and deafness, and myoneurogastrointestinal disorder and encephalopathy) and found 10 cases of optic nerve hypoplasia. Optic nerve hypoplasia occurs in at least 12% of patients with nonsyndromic mitochondrial cytopathies. Although the exact pathogenesis of optic nerve hypoplasia in the context of mitochondrial cytopathy is unknown, we postulate that it is the result of excessive apoptosis during embryonic ganglion cell and/or axonal development from abnormal mitochondrial function and cellular energy metabolism.

Retinal function in infants with optic nerve hypoplasia: electroretinograms to large patterns and photopic flash

AIMS

Optic nerve hypoplasia (ONH), which is defined as a congenital deficiency of retinal ganglion cells, may also involve more distal layers of the retina. We investigated electrophysiological function of the retina in ONH using electroretinograms (ERGs).

METHODS

ERGs were recorded from 48 subjects (3.5-35 months) with unilateral or bilateral ONH. Pattern reversal (4 degrees checks) was presented under chloral hydrate sedation, using an optical system to correct a cycloplegic refraction. A photopic flash stimulus was also used. Fundus photographs were used to measure the disk diameter/disk macula ratio (DD/DM), and to document other clinical signs. Eyes were classified as moderate (0.15-0.3) or severe (<0.15) ONH, and those with DD/DM greater than 0.3 were used as reference eyes.

RESULTS

Pattern ERG recording was completed in 89 eyes and was detectable in 80% of eyes with ONH (61/76 tested) and in all 13 reference eyes. Photopic flash ERGs were of good quality in all eyes. The severity of ONH correlates with the amplitude of the photopic flash b-waves and with the amplitude of the N95 component of the pattern ERG (P<0.01). However, the ERGs to large patterns were well preserved (>3.5 microV) in 10 of 35 eyes with severe ONH. Tortuous retinal vessels in eyes with either moderate or severe ONH were associated with smaller amplitude photopic b-waves and markedly diminished or undetectable pattern ERGs.

CONCLUSIONS

This study supports the hypothesis that retinal dysfunction distal to the ganglion cells is common in ONH, but is not predictable on the basis of ONH severity alone. Additionally, tortuous retinal vessels in ONH may be a sign associated with retinal dysfunction.

Amblyopia characterization, treatment, and prophylaxis

Amblyopia has a 1.6-3.6% prevalence, higher in the medically underserved. It is more complex than simply visual acuity loss and the better eye has sub-clinical deficits. Functional limitations appear more extensive and loss of vision in the better eye of amblyopes more prevalent than previously thought. Amblyopia screening and treatment are efficacious, but cost-effectiveness concerns remain. Refractive correction alone may successfully treat anisometropic amblyopia and it, minimal occlusion, and/or catecholamine treatment can provide initial vision improvement that may improve compliance with subsequent long-duration treatment. Atropine penalization appears as effective as occlusion for moderate amblyopia, with limited-day penalization as effective as full-time. Cytidin-5'-diphosphocholine may hold promise as a medical treatment. Interpretation of much of the amblyopia literature is made difficult by: inaccurate visual acuity measurement at initial visit, lack of adequate refractive correction prior to and during treatment, and lack of long-term follow-up results. Successful treatment can be achieved in at most 63-83% of patients. Treatment outcome is a function of initial visual acuity and type of amblyopia, and a reciprocal product of treatment efficacy, duration, and compliance. Age at treatment onset is not predictive of outcome in many studies but detection under versus over 2-3 years of age may be. Multiple screenings prior to that age, and prompt treatment, reduce prevalence. Would a single early cycloplegic photoscreening be as, or more, successful at detection or prediction than the multiple screenings, and more cost-effective? Penalization and occlusion have minimal incidence of reverse amblyopia and/or side-effects, no significant influence on emmetropization, and no consistent effect on sign or size of post-treatment changes in strabismic deviation. There may be a physiologic basis for better age-indifferent outcome than tapped by current treatment methodologies. Infant refractive correction substantially reduces accommodative esotropia and amblyopia incidence without interference with emmetropization. Compensatory prism, alone or post-operatively, and/or minus lens treatment, and/or wide-field fusional amplitude training, may reduce risk of early onset esotropia. Multivariate screening using continuous-scale measurements may be more effective than traditional single-test dichotomous pass/fail measures. Pigmentation may be one parameter because Caucasians are at higher risk for esotropia than non-whites.

Severe visual impairment and blindness in children in the UK

BACKGROUND

Prevention of visual impairment and blindness in childhood is an international priority. However, many countries do not have contemporary information about incidence and causes, from which the scope and priorities for prevention and treatment can be identified.

METHODS

In the UK, children aged younger than 16 years newly diagnosed with severe visual impairment or blindness (SVI/BL, WHO criteria) during 2000 were identified through national active surveillance schemes in ophthalmology and paediatrics. From these data, we calculated yearly age-group specific incidence and cumulative incidence. Causes were classified by the anatomical site or sites affected and by timing of the insult or insults and causal factors, where known.

FINDINGS

Of 439 newly diagnosed children, 336 (77%) had additional non-ophthalmic disorders or impairments (SVI/BL plus). Total yearly incidence was highest in the first year of life, being 4.0 (95% CI 3.6-4.5) per 10000, with a cumulative incidence by 16 years of age of 5.9 (5.3-6.5) per 10000. 10% (44) of all children died within 1 year of diagnosis of blindness. Prenatal causal factors affected 61% (268) of children, with perinatal or neonatal and childhood factors each affecting 18% (77). Incidence and causes varied with presence of non-ophthalmic impairments or disorders, birthweight, and ethnic origin. At least 75% (331) of children had disorders that were neither potentially preventable nor treatable, with current knowledge.

INTERPRETATION

Severe visual impairment and blindness in childhood in the UK is more common, occurs more frequently in the context of complex non-ophthalmic impairments, and has greater associated mortality, than previously assumed. An increased rate in children of low birthweight and from ethnic minority groups, together with the observed diversity and complexity of the causes, reflect recent secular changes in the population at risk, specific risk factors, and strategies available for treatment.

Optic nerve hypoplasia: Risk factors and epidemiology

OBJECTIVES

To study the epidemiology of optic nerve hypoplasia.

DESIGN AND METHODS

Children with optic nerve hypoplasia and visual impairment were identified through the Swedish Register of Visually Impaired Children. Pre- and perinatal characteristics were obtained from the Medical Birth Registry and by scrutinizing pregnancy and delivery records. Clinical characteristics of children with optic nerve hypoplasia are described. The following risk factors were studied: maternal age, parity, maternal smoking, gestational duration, birth weight, delivery method, Apgar score, maternal disease during pregnancy, drugs used in early pregnancy.

RESULTS

Young maternal age, first parity, maternal smoking, preterm birth and factors associated with preterm birth were risk factors for optic nerve hypoplasia. There was an indicated association with the use of fertility drugs and antidepressant drugs.

CONCLUSIONS

Optic nerve hypoplasia is apparently associated not only with other anomolies, notably of the central nervous system, but also with signs of general disturbance in fetal development.

Unilateral congenital oculomotor nerve palsy, optic nerve hypoplasia and pituitary malformation: a preliminary report

A newborn male presented with complete external third nerve palsy of his right eye immediately at birth. Pediatric examination and MRI of the skull revealed no abnormalities. At the age of six weeks, strabismus surgery was performed to facilitate amblyopia treatment. The muscles appeared small and fibrotic. At the age of ten weeks, a brow suspension of the upper lid and a second strabismus surgery were performed. The amblyopia treatment and patching, applied for half of the waking hours over a period of six weeks, were unsuccessful. At the age of six months, a relative pallor of the right optic nerve head became evident. At the age of three years, at a new examination because of growth deficiency, a second MRI revealed defects involving the pituitary region. We concluded that extraocular muscle abnormality or oculomotor nerve palsy was present together with optic nerve dysplasia and pituitary gland malformation.

A patient with de Morsier and Duane syndromes

de Morsier syndrome, or septo-optic dysplasia, is a developmental malformation complex characterized by optic nerve hypoplasia, dysgenesis of the septum pellucidum, and hypothalamic-pituitary dysfunction. (1,2) In Duane retraction syndrome, there is absence of the sixth nerve nucleus with congenital retraction of the globe and narrowing of the lid fissure in adduction, frequent abduction deficiency, and variable limitation to adduction of the affected eye. (3) The purpose of this report is to present a patient with the uncommon and previously unreported concurrence of both of these congenital malformation complexes, presumably because of a common disturbance of neuronal development.

The normal optic nerve head

BACKGROUND

The normal optic nerve head varies from one person to another, and there is often intraindividual variation as well. Factors such as race and age play an important role in distinguishing what may be considered normal variations in optic nerve head appearance.

METHODS

A literature search and review of the latest studies on the optic nerve head was conducted.

RESULTS

Results of recent studies showed that variations in the average cup-to-disc ratio exist for different races, and with age there is a gradual loss of nerve fibers leading to an overall increase in the cup-to-disc ratio. There is also evidence that congenitally larger optic nerves have larger cup-to-disc ratios and more nerve fibers. Smaller optic nerves, in contrast, have smaller cup-to-disc ratios and fewer nerve fibers. These findings are presented along with sample photographs depicting the normal variations in optic nerve head appearance.

CONCLUSION

Over the past 30 years, technology has allowed for changing views about what may be considered normal in reference to the optic nerve head. This information is valuable to the eye care practitioner in helping to make appropriate patient care management decisions.

The clinical and morphologic spectrum of optic nerve hypoplasia

PURPOSE

The purpose of this study was to characterize the clinical and morphologic spectrum of all children referred for optic nerve hypoplasia to a tertiary referral hospital in Sweden during a 9-year period.

SUBJECTS AND METHODS

A retrospective review was undertaken of the charts of 117 children (age range, 0.25-16 years), treated at the Children's Hospital, Göteberg between 1988 and 1996, after the diagnosis of optic nerve hypoplasia. Ocular fundus morphologic condition was evaluated by digital image analysis of fundus photographs in 50 children, and neuroimaging was performed in 57 children.

RESULTS

Of the 117 children with optic nerve hypoplasia, 66 (56%) were boys and 51 (44%) were girls. Preterm birth occurred in 24 (20%), and 14 (12%) were born small for gestational age. Additional diagnoses, such as fetal alcohol syndrome, septo-optic dysplasia, perinatal adverse events, and neuropsychiatric disorders, were made in 88%; 7% had unilateral optic nerve hypoplasia. Most of the children had small optic disc, cup, and neuroretinal rim areas, as well as retinal vascular abnormalities; 75% were visually impaired, and a high incidence of nystagmus and strabismus was found among these children.

CONCLUSION

This study indicates that optic nerve hypoplasia has a wide clinical and morphologic spectrum and is associated with a broad range of disorders of the central nervous system. It is suggested that differences in the etiology and timing of the lesion as well as associated lesions may explain this spectrum of optic nerve hypoplasia in children.

Diagnostic value of magnetic resonance imaging and planimetric measurement of optic disc size in confirming optic nerve hypoplasia

PURPOSE

This study set out to evaluate magnetic resonance imaging (MRI) and measurement of optic disc size as diagnostic tools for confirming the diagnosis of optic nerve hypoplasia (ONH) in children with impaired growth.

METHODS

MRI was performed to study the size of the intracranial visual pathways, and image analysis measurements of fundus photographs were performed to determine the size of the optic disc. Results from these investigations were compared with those using the gold standard for diagnosis of ONH, which was the clinical eye examination (visual function, ophthalmoscopic signs, or both). Forty children (median age, 9 years; range, 3 to 19 years) with impaired growth were included in the study.

RESULTS

The prevalence of ONH among the children was 15%. MRI classification of the visual pathways had a higher positive predictive value than image analysis measurement of the optic disc size (1.0 vs 0.6).

CONCLUSIONS

MRI is a good tool for confirming the diagnosis of ONH and may thus facilitate early detection. On the other hand, a small optic disc per se is not a definite indicator of ONH but should encourage further investigation with MRI, especially if there is a clinical suspicion of ONH.

Neuroimaging in children with congenital disorders of the peripheral visual system

The study investigates the neurological substrate in children with congenital disorders of the peripheral visual system (CDPVS), i.e. disorders of the anterior visual pathways and the globe. The design is retrospective; brain MRI and/or CT scans were traced and reviewed for 79 of 254 children with CDPVS on our database. The neuroradiological findings were considered in the context of degree of visual impairment (profound [PVI] and severe [SVI]), developmental outcome (setback and non-setback), and mode of imaging (MRI and CT). Scans were abnormal in 40 of 79 (51%) children; 23 of 40 (58%) had more than one lesion; and in some children lesions not previously reported were found. The number of abnormalities per child was significantly higher in the PVI than the SVI group (P<0.05); the level of significance varied according to the method of scanning (MRI, P<0.001; CT, ns). Seven children were known to have had developmental setback; significantly more brain abnormalities per child were found in the group with setbacks than in the group without (P<0.001). Eighty-six percent (24 of 28) of MRI compared with 38% (22 of 58) of CT scans were abnormal. MRI detected more lesions per child than CT (P< 0.001). Thus, a significant amount of brain pathology occurs in children with CDPVS. The number of lesions varies directly with degree of visual impairment and both correlate with developmental outcome. As brain pathology will be only one of many factors influencing developmental progress in visually impaired children, prospective multifactorial studies of the CDPVS population, which include MRI studies of the neurological substrate, will be required to clarify the latter.

Optic nerve hypoplasia secondary to intracranial teratoma

PURPOSE

To postulate a causal relation between optic nerve hypoplasia and a suprasellar teratoma.

METHOD

Case report.

RESULTS

A 6-month-old infant with suprasellar teratoma was visually inattentive and had searching nystagmus. He had moderately severe, bilateral optic nerve hypoplasia with the left eye being somewhat worse than the right eye.

CONCLUSIONS

Optic nerve hypoplasia is a major cause of impaired vision in children and rarely has been attributed to an intracranial tumor. Our case, involving a patient with a suprasellar teratoma and optic nerve hypoplasia, supports a causal relation between the two.

Optic nerve hypoplasia with hypopituitarism and an arachnoid cyst

We describe a 5-month-old boy with bilateral optic nerve hypoplasia associated with visual impairment, growth hormone deficiency and an arachnoid cyst in the right temporal lobe on MRI. Optic nerve hypoplasia is sometimes associated with agenesis of the septum pellucidum, commonly known as septo-optic dysplasia, and/or hypopituitarism. There have been a few reports about its association with other abnormalities of the central nervous system, but none about that with an arachnoid cyst.

Optic nerve hypoplasia: comparative effects in children and rats exposed to alcohol during pregnancy

Children with the fetal alcohol syndrome often have ocular anomalies. These include abnormalities of the eyes and adnexa (strabismus, blepharoptosis, epicanthus), as well as intraocular defects (cataract, glaucoma, persistent hyperplastic primary vitreous, retinal and optic nerve anomalies). Based on the clinical results in an ophthalmological study of a group of Swedish children with the fetal alcohol syndrome, in which optic nerve hypoplasia was found in up to one-half of the group, an experimental study was designed in rats pre- and perinatally exposed to alcohol by means of a liquid diet. The optic nerve was seriously affected. Macroglial cells and optic axons were ultrastructurally damaged. The diameter of the optic nerve cross section, glial cell nuclear area, axonal diameter, and the total number of optic axons showed significantly lower values in the alcohol-exposed group than in the controls. In addition, the retina from the alcohol-exposed animals displayed significantly lower values of the retinal thickness and ganglion cell nuclear volume, as compared to the controls. Thus, rats exposed to alcohol in utero developed hypoplasia of the optic nerve similar to the findings in children born to alcoholic mothers. This strongly supports the hypothesis that prenatal alcohol exposure may adversely affect the development of the optic nerve.

Electrophysiologic alterations in patients with optic nerve hypoplasia

The clinical and electrophysiologic data (electroretinograms and visual evoked potentials) were studied in 45 patients with optic nerve hypoplasia. The patients were divided into three fairly distinct groups on the basis of their electrophysiologic alterations. Group 1 consisted of 13 patients with almost extinguished visual evoked potentials and with mild electroretinographic alterations. These were the cases that are traditionally recognized as optic nerve hypoplasia. The serious visual impairment in these cases was accompanied by various developmental ophthalmologic and nonophthalmologic abnormalities. Group 2 included 26 patients without any significant visual evoked potential or electroretinographic alterations, but with overt funduscopic signs of optic nerve hypoplasia. These patients were consistently suffering from strabismus and/or amblyopia. The visual functions based on visual evoked potential and electroretinographic recordings could be fairly normal apart from a pathologic ophthalmoscopic picture characteristic of optic nerve hypoplasia. Group 3 included six patients with abnormal albeit well-recordable visual evoked potentials and subnormal or negative-type electroretinograms that suggested an accompanying retinal disease. This finding seems to prove that a subset of patients with optic nerve hypoplasia with nystagmus may have a primary retinal abnormality. Our study provides further evidence that optic nerve hypoplasia is not a uniform disease entity.

Follow-up study on premature infants with and without retinopathy of prematurity

The ocular complications in population of 131 premature infants, with and without retinopathy of prematurity (ROP) are reported. An increased incidence of strabismus (20% with ROP and 25% without ROP) and myopia (27.5% with ROP and 8.8% without ROP) was shown. Significant visual loss occurred in 10.7% overall, increasing to 35% with stage 3 disease and 100% with stage 4. With the increased survival rate of premature infants, the relevance to future management of this expanding group of young people is considered.

Aplasia of the optic nerve: report of three cases

Aplasia of the optic nerve is a very rare congenital anomaly characterized by an absence of optic nerve fibers, retinal ganglion cells, and the retinal central blood vessels. It may be associated with a wide range of other congenital abnormalities. In the present article, three cases of aplasia of the optic nerve are described. Its pathology and clinical features are reviewed.

The brightness-sense comparison in patients with optic nerve hypoplasia

The brightness-sense has been assessed for a cohort of individuals with optic nerve hypoplasia, and for a group of normal subjects. It was found to be significantly impaired in the worst eye as compared to the fellow eye in patients with asymmetrical bilateral optic nerve hypoplasia. No difference in brightness between the two eyes was perceived in two patients with segmental optic nerve hypoplasia. The brightness-sense comparison test has not hitherto been applied to patients with optic nerve hypoplasia. The test is simple to use and provides an additional investigative tool for the clinician to detect optic nerve dysfunction.

Optic nerve hypoplasia, encephalopathy, and neurodevelopmental handicap

Abnormalities of the central nervous system are frequently described in optic nerve hypoplasia. In a longitudinal study of 46 consecutive children (32 term, 14 preterm) with bilateral optic nerve hypoplasia 32 (69.5%) had associated neurodevelopmental handicap. Of these, 90% had structural central nervous system abnormalities on computed tomographic brain scans. Neurodevelopmental handicap occurred in 62.5% of the term and 86% of the preterm infants respectively. Term infants had a greater incidence of ventral developmental midline defects and proportionately fewer maternal and/or neonatal complications throughout pregnancy, while encephaloclastic lesions were commoner among the premature infants. An association of optic nerve hypoplasia with the twin transfusion syndrome and prenatal vascular encephalopathies is described.