Medical treatment of acquired nystagmus:

Nystagmus Estimation for Dizziness Diagnosis by Pupil Detection and Tracking Using Mexican-Hat-Type Ellipse Pattern Matching

The detection of nystagmus using video oculography experiences accuracy problems when patients who complain of dizziness have difficulty in fully opening their eyes. Pupil detection and tracking in this condition affect the accuracy of the nystagmus waveform. In this research, we design a pupil detection method using a pattern matching approach that approximates the pupil using a Mexican hat-type ellipse pattern, in order to deal with the aforementioned problem. We evaluate the performance of the proposed method, in comparison with that of a conventional Hough transform method, for eye movement videos retrieved from Gifu University Hospital. The performance results show that the proposed method can detect and track the pupil position, even when only 20% of the pupil is visible. In comparison, the conventional Hough transform only indicates good performance when 90% of the pupil is visible. We also evaluate the proposed method using the Labelled Pupil in the Wild (LPW) data set. The results show that the proposed method has an accuracy of 1.47, as evaluated using the Mean Square Error (MSE), which is much lower than that of the conventional Hough transform method, with an MSE of 9.53. We conduct expert validation by consulting three medical specialists regarding the nystagmus waveform. The medical specialists agreed that the waveform can be evaluated clinically, without contradicting their diagnoses.

[Prism-Induced Gaze Shift and Strabismus Treatment for Ocular Motility Disorders and Anomalous Head Posture]

BACKGROUND

The therapeutic treatment of ocular motility disorders and anomalous head postures (AHP) is often challenging. We report our experience with prism use in these patients.

PATIENTS AND METHODS

Retrospective case series of three patients with ocular motility disorders and associated AHP who were treated with prism correction.

RESULTS

A 37-year-old male with a traumatic left oculomotor nerve palsy suffered from a residual minor depression deficit and a severe elevation palsy. With OS: 10^ base-up he was corrected for left hypotropia only in down gaze. Ten yoked prisms base-up shifted the field of binocular single vision in primary position. A 45-year-old male with traumatic Parinaud syndrome and upward gaze palsy suffered from neck pain due to his pronounced chin elevation. He also had a right amaurosis with secondary exotropia. With OS: 8^ base-up, his AHP was corrected and his neck pain was alleviated. A 69-year-old woman with a left abducens nerve palsy adopted a left turn of 20° to compensate for her deviation in extreme right gaze. With OS: 20^ base-out, her AHP was corrected and she experienced no double vision in primary position.

CONCLUSIONS

Prisms are used to correct strabismic deviations but also can successfully shift images towards another gaze in different clinical scenarios. Reduction of AHP, therefore, can be obtained by a prism-induced gaze shift in the direction of the motility restriction.

Development of a core outcome set for amblyopia, strabismus and ocular motility disorders: a review to identify outcome measures

BACKGROUND

Core Outcome Sets (COS) are defined as the minimum sets of outcomes that should be measured and reported in all randomised controlled trials to facilitate combination and comparability of research. The aim of this review is to produce an item bank of previously reported outcome measures from published studies in amblyopia, strabismus and ocular motility disorders to initiate the development of COS.

METHODS

A review was conducted to identify articles reporting outcome measures for amblyopia, strabismus and ocular motility disorders. Using systematic methods according to the COMET handbook we searched key electronic bibliographic databases from 1st January 2011 to 27th September 2016 using MESH terms and alternatives indicating the different subtypes of amblyopia, strabismus and ocular motility disorders in relation to treatment outcomes and all synonyms. We included Cochrane reviews, other systematic reviews, controlled trials, non-systematic reviews and retrospective studies. Data was extracted to tabulate demographics of included studies, primary and secondary outcomes, methods of measurement and their time points.

RESULTS

A total of 142 studies were included; 42 in amblyopia, 33 in strabismus, and 68 in ocular motility disorders (one study overlap between amblyopia and strabismus). We identified ten main outcome measure domains for amblyopia, 14 for strabismus, and ten common "visual or motility" outcome measure domains for ocular motility disorders. Within the domains, we found variable nomenclature being used and diversity in methods and timings of measurements.

CONCLUSION

This review highlights discrepancies in outcome measure reporting within published literature for amblyopia, strabismus and ocular motility and it generated an item bank of the most commonly used and reported outcome measures for each of the three conditions from recent literature to start the process of COS development. Consensus among all stakeholders including patients and professionals is recommended to establish a useful COS.

The Guillain-Mollaret triangle in action

The Guillain-Mollaret triangle comprises the ipsilateral red nucleus in the midbrain, the inferior olive in the medulla and the contralateral dentate nucleus in the cerebellum: together, these form the dentato-rubro-olivary pathway. Pathology in this triangle disinhibits (and so activates) the inferior olivary nucleus. The olivary nucleus then hypertrophies and its rhythmical discharges may manifest clinically as oculopalatal tremor. We describe three cases with either oculopalatal tremor or MRI evidence of olivary hypertrophy caused by vascular insults to this triangle. It is not clear why only some patients have the oculopalatal tremor. Olivary hypertrophy can be confused with demyelination if the imaging is not put into clinical context. Oculopalatal tremor may occur without olivary hypertrophy since the nucleus atrophies with time. Oculopalatal tremor does not respond to medical treatment. A better understanding of the mechanism of the discharge at a cellular level may lead to more targeted medical treatments.

Optical Management Using Monovision and Yoked Prism for Acquired Strabismus and Nystagmus Secondary to a Neurodegenerative Disease

Acquired involuntary eye movement disorders, including noncomitant strabismus, nystagmus, and saccadic dyskinesia, are common ocular manifestations of many neurodegenerative diseases. These patients may experience visual symptoms, such as blurred vision, diplopia, and oscillopsia, which can significantly impact their use of vision. The goal of the management for these patients is to reduce the visual symptoms using any combination of available management strategies. This case report discusses the effective optical management using the combination of spectacle monovision correction and yoked prism to improve visual symptoms in a patient with olivopontocerebellar atrophy.

Retrospective study of recession of four horizontal rectus muscle in periodic alternating nystagmus

Purpose

Periodic alternating nystagmus (PAN) is a spontaneous horizontal nystagmus observed in disorders of the central nervous system. Patients with congenital PAN complain of oscillating vision at high rates. Medication is the first-choice treatment for PAN; however, clinicians still seek better therapy. The aim of this study was to evaluate outcomes of recession of four horizontal rectus muscle (R-FHR) in patients with congenital PAN.

Patients and methods

This study reports a retrospective case series of ten patients (seven males and three females; mean age 24.4±10.9) with congenital PAN who underwent R-FHR between 2007 and 2012, which was performed by the same surgeon at the Hyogo College of Medicine. Patients were evaluated for complications, recession amount, deviation angle, eye movements including a nystagmus amplitude, and visual acuity during pre- and post-operative periods.

Results

Pre-operatively, patients complained of oscillating vision, abnormal head posture, esotropia, and congenital superior oblique palsy. Post-operatively, changes from the previous observations of nystagmus amplitudes and abnormal head posture demonstrated a complete reversal in all patients. In addition, visual acuity determined with a Snellen chart improved in two patients. However, esotropia occurred in three patients who underwent additional strabismus surgery 2 days after R-FHR. R-FHR was particularly effective in eight patients who pre-operatively had periodic oscillating vision with a regular pattern of periodic nystagmus.

Conclusion

We demonstrated that ten patients with congenital PAN had improved vision following R-FHR, indicating that R-FHR was an effective procedure, especially in patients suffering PAN with periodic oscillating vision.

Neuro-Ophthalmology Annual Review

The aim of this study was to update the practicing ophthalmologist on the English-language neuro-ophthalmology literature from the prior year. This study is a review of English-language literature from August 1, 2012, to August 1, 2013. The authors searched PubMed articles published from August 1, 2012, to August 1, 2013, limited to English-language publications including original articles, review articles, and case reports and excluding letters to the editor, unpublished work, and abstracts. We researched the following topics: pupillary abnormalities, eye movement dysfunction, neuromuscular diseases, optic neuropathies, optic neuritis and demyelinating disease including multiple sclerosis, lesions of the chiasm and posterior primary visual pathways, elevated intracranial pressure, tumors and aneurysms affecting the visual pathways, vascular diseases, higher visual functions, and neuroimaging advances. We intend to share clinically relevant literature of the past year with the practicing ophthalmologist. We aimed to highlight remarkable and interesting literature rather than exhaustively including all new neuro-ophthalmological publications of the year. We reviewed literature in the past year with a focus on relevance and novelty. This review updates the comprehensive ophthalmologist on neuro-ophthalmic topics.