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Lausanne, Switzerland

Kawasaki A.,Hopital Ophtalmique Jules Gonin | Miller N.R.,Wilmer Eye Institute | Kardon R.,University of Iowa
Ophthalmology | Year: 2010

Objective: To identify clinical and pupillographic features of patients with a relative afferent pupillary defect (RAPD) without visual acuity or visual field loss caused by a lesion in the dorsal midbrain. Design: Experimental study. Participants and Controls: Four patients with a dorsal midbrain lesion who had normal visual fields and a clinically detectable RAPD. Methods: The pupil response from full-field and hemifield light stimulation over a range of light intensities was measured by computerized binocular pupillography. Main Outcome Measures: The mean of the direct and consensual pupil response to full-field and hemifield light stimulation was plotted as a function of stimulus light intensity. Results: All 4 subjects showed decreased pupillographic responses at all intensities to full-field light stimulation in the eye with the clinical RAPD. The pupillographic responses to hemifield stimulation showed a homonymous pattern of deficit on the side ipsilateral to the RAPD, similar to that observed in a previously reported patient with an optic tract lesion. Conclusions: The basis of a midbrain RAPD is the nasal-temporal asymmetry of pupillomotor input that becomes manifest when a unilateral postchiasmal lesion interrupts homonymously paired fibers traveling in the contralateral optic tract or midbrain pathway to the pupillomotor center, respectively. The pupillographic characteristics of an RAPD resulting from a dorsal midbrain lesion thus resemble those of an RAPD resulting from a unilateral optic tract lesion, but without the homonymous visual field defect. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. © 2010 American Academy of Ophthalmology. Source

Munch M.,Ecole Polytechnique Federale de Lausanne | Kawasaki A.,Hopital Ophtalmique Jules Gonin | Kawasaki A.,Umea University
Current Opinion in Neurology | Year: 2013

PURPOSE OF REVIEW: The discovery of a new class of intrinsically photosensitive retinal ganglion cells (ipRGCs) revealed their superior role for various nonvisual biological functions, including the pupil light reflex, and circadian photoentrainment. RECENT FINDINGS: Recent works have identified and characterized several anatomically and functionally distinct ipRGC subtypes and have added strong new evidence for the accessory role of ipRGCs in the visual system in humans. SUMMARY: This review summarizes current concepts related to ipRGC morphology, central connections and behavioural functions and highlights recent studies having clinical relevance to ipRGCs. Clinical implications of the melanopsin system are widespread, particularly as related to chronobiology. © 2013 Wolters Kluwer Health | Lippincott Williams &Wilkins. Source

Sundaram S.V.,Indiana University | Purvin V.A.,Indiana University | Kawasaki A.,Hopital Ophtalmique Jules Gonin
Clinical and Experimental Ophthalmology | Year: 2010

Background: Previous reports have emphasized the self-limited nature of idiopathic neuroretinitis. There is less information about a subgroup of patients who suffer recurrent episodes with worse visual outcome. We sought to better characterize the clinical features of recurrent idiopathic neuroretinitis including the effects of immunosuppressive treatment. Methods: Retrospective chart review of neuroretinitis patients from a single institution from 1983 to 2008. Inclusion criteria included two or more episodes of acute visual loss with disc oedema and macular exudates in a star pattern. Cases due to a specific infectious or inflammatory aetiology were excluded. Results: Forty-one patients were included with an average follow up of 67 months. Median age at the time of the first episode was 28 years (range 10-54 years). Attacks were bilateral sequential in 34 patients (83%). We documented a total of 147 episodes in 75 eyes with an average of 3.6 attacks per patient. The average interval between attacks was 3 years. Visual field loss had a nerve fibre bundle pattern in most cases. Only 36% of eyes retained 6/12 or better visual acuity and greater than two-thirds of their visual field. Long-term immunosuppressive treatment in 13 patients decreased the attack rate by 72%. Conclusions: Recurrent idiopathic neuroretinitis typically affects young adults, with no gender preference. Recovery is limited and visual loss is cumulative with repeated attacks, often resulting in severe permanent visual loss. Immunosuppressive treatment appears to lessen the attack frequency. © 2010 The Authors. Journal compilation © 2010 Royal Australian and New Zealand College of Ophthalmologists. Source

Herbst K.,Glostrup Hospital | Sander B.,Glostrup Hospital | Lund-Andersen H.,Glostrup Hospital | Broendsted A.E.,Glostrup Hospital | And 4 more authors.
BMC Ophthalmology | Year: 2012

Background: The activity of melanopsin containing intrinsically photosensitive ganglion retinal cells (ipRGC) can be assessed by a means of pupil responses to bright blue (appr.480 nm) light. Due to age related factors in the eye, particularly, structural changes of the lens, less light reaches retina. The aim of this study was to examine how age and in vivo measured lens transmission of blue light might affect pupil light responses, in particular, mediated by the ipRGC. Methods: Consensual pupil responses were explored in 44 healthy subjects aged between 26 and 68 years. A pupil response was recorded to a continuous 20 s light stimulus of 660 nm (red) or 470 nm (blue) both at 300 cd/m 2 intensity (14.9 and 14.8 log photons/cm 2/s, respectively). Additional recordings were performed using four 470 nm stimulus intensities of 3, 30, 100 and 300 cd/m 2. The baseline pupil size was measured in darkness and results were adjusted for the baseline pupil and gender. The main outcome parameters were maximal and sustained pupil contraction amplitudes and the postillumination response assessed as area under the curve (AUC) over two time-windows: early (010 s after light termination) and late (1030 s after light termination). Lens transmission was measured with an ocular fluorometer. Results: The sustained pupil contraction and the early poststimulus AUC correlated positively with age (p = 0.02, p = 0.0014, respectively) for the blue light stimulus condition only. The maximal pupil contraction amplitude did not correlate to age either for bright blue or red light stimulus conditions. Lens transmission decreased linearly with age (p<0.0001). The pupil response was stable or increased with decreasing transmission, though only significantly for the early poststimulus AUC to 300 cd/m2 light (p = 0.02). Conclusions: Age did not reduce, but rather enhance pupil responses mediated by ipRGC. The age related decrease of blue light transmission led to similar results, however, the effect of age was greater on these pupil responses than that of the lens transmission. Thus there must be other age related factors such as lens scatter and/ or adaptive processes influencing the ipRGC mediated pupil response enhancement observed with advancing age. © 2012 Herbst et al; licensee BioMed Central Ltd. Source

Hafezi F.,Institute for Refractive and Ophthalmic Surgery IROC | Majo F.,Hopital Ophtalmique Jules Gonin | El Danasoury A.M.,Refractive Surgery and Cornea Unit
Journal of Refractive Surgery | Year: 2010

PURPOSE: To report the effect of corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A (UVA) on the optical and material characteristics of a posterior chamber phakic intraocular lens (Visian ICL, STAAR Surgical). METHODS: Optical and material characteristics were assessed in vitro, analyzing potential changes in riboflavin staining, dioptric power, transmission characteristics, and surface structure. A total of 9 lenses were analyzed: 3 lenses were irradiated with 0.23 mW/cm2, the maximal intensity that may be encountered during actual surgery; 3 lenses were irradiated with 2.3 mW/cm2, 10 times the maximal intensity encountered during surgery; and 3 lenses served as controls. RESULTS: Following CXL with UVA and riboflavin, no changes were observed in the parameters tested; in particular, dioptric power and transmission characteristics were similar before and after CXL. CONCLUSIONS: Cross-linking with UVA and riboflavin does not affect the optical and material characteristics of the Visian ICL after irradiation with the maximal UVA energy levels that may be encountered during surgery. Even when the UVA irradiation dose was increased by a factor of 10, no changes were observed. Copyright © SLACK Incorporated. Source

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