Anatomic Features and Function of the Macula and Outcome of Surgical Tenotomy and Reattachment in Achiasma

doi:10.1016/j.ophtha.2012.12.037

Ophthalmology

Volume 120, Issue 7, July 2013, Pages 1469-1475

https://doi.org/10.1016/j.ophtha.2012.12.037 Get rights and content

Objective

To examine the anatomic features and function of the macula in achiasma and to compare visual acuity, eye movements, foveation, and eye velocity before and after tenotomy and reattachment (T&R) surgery.

Design

Case series.

Participants

Two children with isolated achiasma.

Methods

Ophthalmologic examinations, brain magnetic resonance imaging, full-field and multifocal electroretinography (ERG), visual evoked potentials (VEPs), spectral-domain optical coherence tomography (OCT), eye-movement recordings, and unilateral T&R in 1 patient.

Main Outcome Measures

Visual acuity before and after surgery, macular anatomic features and function, and eye velocity before and after T&R surgery in 1 patient.

Results

Magnetic resonance imaging and VEP confirmed absence of decussation of retinofugal fibers in both patients. Visual acuity was 20/100 and 20/200. The anatomic features and function of the fovea and macula were normal by OCT and multifocal ERG. After T&R, there was a marked reduction in horizontal eye velocity and monocular visual acuity improved to 20/80.

Conclusions

The finding that the macula is normal in achiasma suggests that reduced acuity is the result of retinal image motion from nystagmus. Two-muscle T&R reduces horizontal retinal image motion and can improve visual acuity in achiasma or patients with infantile nystagmus.

Financial Disclosure(s)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Section snippets

Patients and Methods

The records of patients with infantile nystagmus, who were seen at Children's Hospital and Regional Medical Center, Seattle, Washington, were reviewed retrospectively. The research followed the tenets of the Declaration of Helsinki and chart review was approved by the institutional review board. From this chart review, 2 children were identified with findings consistent with isolated achiasma. All children with hypochiasma associated with optic nerve hypoplasia and 1 child with achiasma in the

Case 1

A girl who was 3 years and 4 months of age was evaluated for infantile nystagmus and reduced visual acuity. There was no family history of infantile nystagmus. Development was age appropriate. Past medical history was relevant for positive purified protein derivative skin conversion treated with rifampin and isoniazid for 9 months. Height, weight, and head circumference were normal. Systemic and neurologic examination results were normal.

Visual acuity was 20/100 with Allen cards under binocular

Discussion

This study showed normal anatomic features and function of the macula in achiasma despite 20/100 to 20/200 visual acuity. Imaging data obtained with spectral-domain OCT indicate that there is a normal foveal pit and normal-appearing cone density peak at the fovea. An mfERG indicated the cone density amplitude of the central hexagon (2° subtense) centered on the fovea was normal. Given the highest visual resolution is in the central 2° centered on the fovea, the data indicate that macular

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A reduced visual pathway response in infantile nystagmus syndrome
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Citation Excerpt :
Data were compared to control children using the same data analysis.16 When tolerated, eye movements were recorded by video-oculography (VOG) using published methods.2,18 VOG resolution was ±0.5° at 60 Hz.
To investigate visual cortical responses in children with infantile nystagmus syndrome (INS) and the potential contribution of foveation periods.
The medical records of children with INS who had visual evoked potential (VEP) recordings to reversing checkerboards and onset of horizontal gratings were reviewed retrospectively. VEP recordings underwent objective selective averaging for extraction of brief periods having consistent amplitude and timing with the stimulus presentation. VEP amplitude, latency, and signal-to-noise ratios (SNR) were compared to results from published age-matched controls under the same conditions. Relative foveation in INS subjects was determined from the proportion of time a video-oculography recording met eye position and velocity criteria.
A total of 26 children met inclusion criteria. Selective averaging increased VEP amplitude and SNR in INS by 270%-420% compared to standard averaging (P < 0.0001). The INS change in VEP response was greater for reversing checkerboard stimulation than horizontal-grating onset and was significantly greater than that in controls (P < 0.001). Latency was not changed by selective averaging. Relative foveation was correlated with increasing VEP amplitude (P = 0.02) and number of trials chosen for selective averaging (P < 0.01). After selective averaging, relative foveation correlated with VEP amplitude to reversing checkerboards only (P = 0.007).
Nystagmus likely causes a reduced visual cortical response in children with INS. A significantly larger response can be extracted from brief periods during nystagmus eye movements, supporting the hypothesis that the INS visual system generates a larger cortical signal during brief foveation periods.
Congenital visual pathway abnormalities: A window onto cortical stability and plasticity
2015, Trends in Neurosciences
Sensory systems project information in a highly organized manner to the brain, where it is preserved in maps of the sensory structures. These sensory projections are altered in congenital abnormalities, such as anophthalmia, albinism, achiasma, and hemihydranencephaly. Consequently, these abnormalities, profoundly affect the organization of the visual system. Surprisingly, visual perception remains largely intact, except for anophthalmia. Recent brain imaging advances shed light on the mechanisms that underlie this phenomenon. In contrast to animal models, in humans the plasticity of thalamocortical connections appears limited, thus demonstrating the importance of cortical adaptations. We suggest that congenital visual pathway abnormalities provide a valuable model to investigate the principles of plasticity that make visual representations available for perception and behavior in humans.
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: Manuscript no. 2012-1162.

: Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

: Supported by an unrestricted grant from grant from the Peter LeHaye, Barbara Anderson, and William O. Rogers Endowment Funds, Seattle, Washington.

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Original articleAnatomic Features and Function of the Macula and Outcome of Surgical Tenotomy and Reattachment in Achiasma

Objective

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

Financial Disclosure(s)

Section snippets

Patients and Methods

Case 1

Discussion

Am J Ophthalmol

J AAPOS

Ophthalmology

J AAPOS

J AAPOS

See-saw nystagmus in dogs and humans: an international, across-discipline, serendipitous collaboration

Neurology

Target recognition and visual maps in the thalamus of achiasmatic dogs

Nature

Original article
Anatomic Features and Function of the Macula and Outcome of Surgical Tenotomy and Reattachment in Achiasma