Spectrum of optic nerve hypoplasia.

Optic nerve hypoplasia is a non-progressive condition characterised by subnormal vision and a subnormal number of optic nerve axons. It may be unilateral or bilateral, isolated or combined with other defects. Analysis of fundus photographs from a series of 7 patients with a stationary abnormality of different degrees showed that the functional defects could be closely correlated with defects in the retinal nerve fibre layer. Our observations show that the condition has a wide range of both functional and anatomical defects and that a subnormal diameter of the optic disc is not a requisite for the diagnosis. Presumably, there is also a wide variety of causes, not only a primary failure of development of retinal ganglion cells. We suggest that optic nerve hypoplasia can be viewed as a non-specific manifestation of damage to the visual system, sustained any time before its full development.     

Maternal anticonvulsants and optic nerve hypoplasia.

Seven patients with optic nerve hypoplasia, born of epileptic mothers, are presented. All the mothers took anticonvulsants during pregnancy. The possibility that maternal anticonvulsant therapy may play a role in the genesis of optic nerve hypoplasia is discussed in the light of what is known about the teratogenicity of these agents.     

Aniridia and optic nerve hypoplasia

BACKGROUND: This study evaluates, in patients with aniridia, the prevalence of optic nerve hypoplasia and its association with foveal hypoplasia. METHODS: The medical records of 56 patients with aniridia (31 female, 25 male, mean age 33 years, range 2-74 years) were retrospectively evaluated for optic nerve and foveal hypoplasia. The difference in prevalence of foveal hypoplasia in patients with and without optic nerve hypoplasia was compared using Fisher's exact test. RESULTS: Six of 56 patients, 10.7% (95% CI: 4.8-21.5%), had optic nerve hypoplasia; hypoplasia was found in both eyes of five binocular patients and in one monocular patient. The prevalence of foveal hypoplasia was higher in aniridia patients with optic nerve hypoplasia than in those without (50.0 vs 6.0%); this difference did not achieve statistical significance (P=0.10). CONCLUSIONS: Clinically apparent optic nerve hypoplasia is found in roughly 10% of patients with aniridia and may occur independently or in association with foveal hypoplasia.     

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.     

Relative hypoplasia of the optic nerve

Meticulous comparison of optic nervehead size has revealed detectable differences in as many as 10% of patients. In many cases the larger nervehead has a larger cup. This may result in the false impression of glaucoma and may be the most common cause of asymmetric cupping in the absence of active, progressive disease. Two cases demonstrating this finding are reviewed with a discussion of its detection and diagnosis.     

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.     

Light-adapted electroretinograms in optic nerve hypoplasia

The purpose of the study is to characterise retinal function using light-adapted electroretinograms (ERGs) in a series of young children with ONH, congenital dysplasia of retinal ganglion cells. ERGs were recorded with chloral hydrate sedation in 27 children with ONH (18 with bilateral and 9 with unilateral ONH, age 4–35 months) and an adult reference population (n = 12). Stimuli included ISCEV standard flash, oscillatory potentials (OPs) and standard flicker as well as a light-adapted luminance–response series (photopic hill). The disc diameter to disc macula (DD:DM) ratio was measured from fundus photographs. The results are eyes with ONH, classified by DD:DM, were severe (≤0.15, n = 22), moderate (0.16–0.30, n = 22), mild (0.31–0.35, n = 1), and fellow eyes (>0.35, n = 9), all had prolonged ERG implicit times and smaller i-waves than those of adults. Eyes with moderate or severe ONH also had smaller amplitudes for OPs and flicker ERGs and required stronger flashes to obtain the peak b-wave amplitude. Abnormalities of the photopic hill were a common but inconsistent feature of ONH and were not indicative of ONH severity. Abnormalities of the photopic hill of the ERG suggest that some cases of ONH may have retinal dysfunction with specific deficits in the ON or OFF pathways of the retina. ONH is a complex and heterogeneous condition that may involve dysfunction distal to the retinal ganglion cells.     

Electroretinographical study of the hypoplasia of the optic nerve.

Out of 22 sporadic cases of hypoplasia of the optic nerve, 16 were bilateral and 6 unilateral. The sex distribution was equal in the bilateral cases, while all our unilateral cases were females. Visual impariment was severe in all our cases. There was total blindness or only light perception. The pupillary reflexes were absent or very slow. Only one case had a rather good visual acuity (1/10) with a constricted visual field. In addition to the typical aspect of hypoplasia of the optic disc, some cases showed an obvious or suspected retinal degereration, such as a marked choroidal pattern with pigmentary dystrophy of the posterior pole. The ERG was normal in most cases, and showed no modification with increasing age. No supranormal recordings were obtained. Out of 36 eyes, 12 had a subnormal response. Seven showed an involvement only of the scotopic response, one only of the photopic response and four of both responses. The reduction of the ERG amplitude was rather mild in most cases. The ERG was never extinguished. The temporal characteristics were normal in all our cases with two exceptions.     

Superior segmental optic nerve hypoplasia in youth

Purpose  The clinical characteristics of superior segmental optic nerve hypoplasia (SSOH) in youth were investigated to help establish diagnostic criteria. Methods  Eleven eyes of seven young patients (male/female ratio, 3/4; age, 15.1 ± 3.4 years) who had good visual acuity and inferior visual field defects (VFDs) were evaluated. Goldmann and Humphrey perimetries and optic disc morphology were analyzed, and the patients were prospectively followed for a long period. Results  Visual field defects were wedge shaped and oriented to the blind spot, but discontinuous in mild cases. Nerve fiber layer defects (NFLDs) were consistent with the VFDs. The optic disc appearance was variable, with double ring signs in seven eyes, small discs in three eyes, and an incomplete topless disc in one eye. The mothers of none of the patients had gestational diabetes. Visual field defects did not progress during the prospective 8.3 ± 1.3 years follow-up. Conclusions  Characteristic VFD patterns on Goldmann perimetry and corresponding NFLDs are important in the diagnosis of SSOH, but not optic disc morphology.     

Superior segmental optic nerve hypoplasia: The topless disc syndrome

BackgroundOptic nerve hypoplasia is a well-known congenital maldevelopment presenting with an abnormally small optic nerve head occupying the central aspect of a normally sized chorioscleral canal. Characteristically, the optic nerve head is surrounded by scleral anlage with a “double ring sign.” Less commonly appreciated, however, is the fact that optic nerve hypoplasia may be sectorial rather than total and involving only the superior aspect of the optic disc with corresponding inferior visual field loss.Case ReportA 51-year-old woman presented with a previous diagnosis of idiopathic optic atrophy superiorly in the left eye. Detailed observation revealed that the disc was not atrophic superiorly but actually hypoplastic, and the patient received a conclusive diagnosis of superior segmental optic nerve hypoplasia.ConclusionsIt must be appreciated that optic nerve hypoplasia can also affect solely the superior aspect of the disc with subsequent functional deficits. It is important to differentiate this syndrome from true optic atrophy to ensure proper management.