Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency and progressive retinopathy: one case report followed by ERGs, VEPs, EOG over a 17-year period.

BACKGROUND: LCHAD (long-chain 3-hydroxyacyl-CoA dehydrogenase) deficiency is a rare genetic disorder of mitochondrial long-chain fatty acid oxidation inherited as a recessive trait. Affected patients can present with hypoglycaemia, rhabdomyolysis and cardiomyopathy. About half of the patients may suffer from retinopathy. CASE REPORT: A 19-year-old girl was diagnosed as suffering from LCHAD deficiency with recurrent rhabdomyolysis episodes at the age of 7 months by an inaugural coma with hypoglycaemia and hepatomegaly. Appropriate dietary management with carnitine supplementation was initiated. Retinopathy was diagnosed at age two. Ophthalmological assessments including visual acuity, visual field, OCT, flash ERGs, P-ERG, flash VEPs and EOG recordings were conducted over a 17-year period. RESULTS: Visual acuity was decreased. Fundi showed a progressive retinopathy and chorioretinopathy. Photophobia was noticed 2 years before the decrease in photopic-ERG amplitude with normal scotopic-ERGs. Scotopic-ERG amplitude decreased 10 years after the decrease in photopic-ERG amplitude. No EOG light rise was observed. Flash VEPs remained normal. These results suggest that the cone system dysfunction occurs largely prior to the rod system dysfunction with a relative preservation of the macula function. COMMENTS: This dysfunction of cones prior to the dysfunction of rods was not reported previously. This could be related to mitochondrial energy failure in cones as cones are greater consumers of ATP than rods. This hypothesis needs to be further confirmed as other long-chain fatty oxidation defective patients (VLCAD and CPT2 deficiencies) do not exhibit retinopathy.

Ultrasound assessment of ocular vascular effects of repeated intravitreal injections of ranibizumab for wet age-related macular degeneration.

PURPOSE: Determine the effect of repeated intravitreal injections of ranibizumab (0.5 mg; 0.05 ml) on retrobulbar blood flow velocities (BFVs) using ultrasound imaging quantification in twenty patients with exudative age-related macular degeneration treated for 6 months. METHODS: Visual acuity (ETDRS), central macular thickness (OCT), peak-systolic, end-diastolic and mean-BFVs in central retinal (CRA), temporal posterior ciliary (TPCA) and ophthalmic (OA) arteries were measured before, 2 days, 3 weeks and 6 months after the first injection. Patients were examined monthly and received 1-5 additional injections depending on ophthalmologic examination results. RESULTS: Six months after the first injection, a significant increase in visual acuity 50.9 ± 25.9 versus 44.4 ± 21.7 (p < 0.01) and decrease in mean central macular thickness 267 ± 74 versus 377 ± 115 µm (p < 0.001) were observed compared to baseline. Although mean-BFVs decreased by 16%±3% in CRA and 20%±5% in TPCA (p < 0.001) 2 days after the first injection, no significant change was seen thereafter. Mean-BFVs in OA decreased by 19%±5% at week 3 (p < 0.001). However, the smallest number of injections (two injections) was associated with the longest time interval between the last injection and month 6 (20 weeks) and with the best return to baseline levels for mean-BFVs in CRA, suggesting that ranibizumab had reversible effects on native retinal vascular supply after its discontinuation. Moreover, a significant correlation between the number of injections and percentage of changes in mean-BFVs in CRA was observed at month 6 (R = 0.74, p < 0.001) unlike TPCA or OA. CONCLUSION: Ranibizumab could impair the native choroidal and retinal vascular networks, but its effect seems reversible after its discontinuation.

Retinal involvement in two unrelated patients with Myhre syndrome.

Myhre syndrome is a very rare condition described thirty years ago and related to mutations in the SMAD4 gene. It has been reported in 19 patients, including 13 males and 6 females before the recent finding of heterozygous mutations in the SMAD4 gene in 19 patients. It is characterized by mental retardation, short stature, muscle hypertrophy, limitation of joints movements, deafness, skeletal anomalies, and facial dysmorphism. Ophthalmological involvement includes hypermetropia and congenital cataract. We report here the new finding of retinal involvement including retinitis pigmentosa and maculopathy in two unrelated patients with Myhre syndrome. The patient with retinitis pigmentosa carried the p.I500T mutation in SMAD4, but no mutation was found in the patient with the maculopathy.

Evaluation of retinal function and flicker light-induced retinal vascular response in normotensive patients with diabetes without retinopathy.

PURPOSE: To correlate retinal function with vascular response to flicker light in normotensive patients with diabetes without diabetic retinopathy (DR). METHODS: Twenty-eight normotensive patients with diabetes (11 with type 1, 17 with type 2) without DR and 28 sex- and age-matched healthy control subjects underwent color vision and contrast sensitivity testing, pattern, full-field, and multifocal electroretinography, and evaluation of the vascular response to flicker light with the dynamic vessel analyzer. RESULTS: In the patients with diabetes, electroretinogram (ERG) pattern responses, b-wave in the scotopic bright flash ERG, a-wave and b-wave in the photopic single-flash ERG, and oscillatory potential responses were significantly impaired compared with those in control subjects. Vascular response to flicker light was also impaired in patients with diabetes compared with controls. In the whole population, correlations were found between flicker light-induced arterial retinal vasodilation and the amplitude and implicit time of the N95 wave of pattern ERG (r = -0.27, P = 0.047 and r = -0.35, P = 0.008, respectively), the b-wave implicit time of rod ERG (r = -0.36; P = 0.01) and the oscillatory potentials (r = 0.4; P = 0.003), suggesting that impairment of the vascular response to flicker light may reflect inner retinal neural impairment. However, no correlation between these factors was found when only patients with diabetes were considered. CONCLUSIONS: In patients with diabetes, neural and neurovascular dysfunctions both precede the onset of clinically detectable DR. To which extent these abnormalities are related to each other remains to be determined. (ClinicalTrials.gov number, NCT00839150.)

H244R VSX1 is associated with selective cone ON bipolar cell dysfunction and macular degeneration in a PPCD family.

PURPOSE: To elucidate the retinal dysfunction and the molecular basis of posterior polymorphous corneal dystrophy (PPCD) associated with macular dystrophy, both inherited in a dominant manner through a three-generation family. METHODS: Ophthalmologic examinations including slit lamp examination, visual acuity tests, fundus visualization by scanning laser ophthalmoscopy, fluorescein angiography, color vision tests, electro-oculography, photopic and scotopic electroretinography (ERG) according to the International Society for Clinical Electrophysiology of Vision (ISCEV) protocols, and oscillatory potential (OP) recordings were conducted on affected family members. Corneal button from one affected patient was examined by transmission electron microscopy. All exons and intron-exon boundaries of the VSX1 and the COL8A2 genes were amplified by polymerase chain reaction and sequenced. RESULTS: The presence of endothelial cells that have epithelial-like features with multiple layers, desmosomal junctions, and microvillous projections supports the diagnosis of PPCD. Sequence analysis indicated that the H244R variant in the VSX1 segregated with corneal and macular disease phenotypes in this family. Electrophysiologic studies indicated normal scotopic ERG findings, decreased amplitude of the photopic b-wave, photopic OP2 and OP3 barely recordable with a preserved OP4 amplitude, and variably decreased 30-Hz flicker amplitude. CONCLUSIONS: The human VSX1 is required for cone ON bipolar cell function but not for rod and cone OFF bipolar cells, giving a unique example of such a selective heritable retinal defect in humans. Furthermore, the authors provide the first clinical support for a new alternative role of VSX1 in cone biology, probably similar to that proposed for its goldfish ortholog during retinal differentiation.

Recommendations for a toxicological screening ERG procedure in laboratory animals.

Electroretinography, using laboratory animals, is a commonly used technique for determining the retinal toxicity of chemical agents. In this paper, guidelines for performing this test are provided. The physiologic basis for visual testing is presented with attention to inter-species differences. Technical aspects of animal recordings are reviewed, including animal preparation, stimulation, signal conditioning, recording and data analysis. Finally, suggested protocols for recording in diurnal and nocturnal species are presented.

In vivo anterior segment imaging in the rat eye with high speed white light full-field optical coherence tomography.

We present a new high speed full-field optical coherence tomography (OCT) instrument, the first full-field OCT system that is capable of in vivo ocular imaging. An isotropic resolution of ~ 1 mum is achieved thanks to the use of a xenon arc lamp source and relatively high numerical aperture microscope objectives in a Linnik-type interferometer. Full-field illumination allows the capture of two-dimensional en face images in parallel, using a fast CMOS camera as detector array. Each en face image is acquired in a 4 ms period, at a maximum repetition rate of 250 Hz. Detection sensitivity per en face image is 71 dB. Higher sensitivity can be achieved by image correlation and averaging, although frame rate is reduced. We present the first preliminary results of in vivo imaging in the anterior segment of the rat eye, which reveal some cellular features in the corneal layers.

Ocular tissue imaging using ultrahigh-resolution, full-field optical coherence tomography.

PURPOSE: Ultrahigh-resolution, full-field optical coherence tomography (OCT), which uses a white light source, allows bidimensional, noninvasive tomographic imaging without scanning. The goal of the present study was to apply full-field OCT to ocular tissue imaging in an attempt to explore the capabilities of the technique. METHODS: This full-field OCT system uses a Linnik-type interferometer with a tungsten-halogen source. The spatial resolution is 0.9 x 0.7 microm (transverse x axial). Unstained tissue samples (cornea, lens, retina, choroid, and sclera) and whole, unfixed eyes of rat, mouse, and pig were examined under immersion. A charge-coupled device (CCD) camera recorded a pair of interferometric images that were combined to display en face (i.e., in the x-y plane) tomographic images in real time. The acquisition time per tomographic image, which includes summation of 10 raw images, was on the order of 1 s. Postprocessing allows volumetric navigation through the image stack as well as three-dimensional (3D) imaging. RESULTS: Cellular-level resolution was achieved in isolated tissue samples. En face (x-y) images revealed corneal epithelial and stromal cells, lens fibers, nerve fibers, major vessels, and retinal pigment epithelial cells. In x-z reconstructions, cellular layers within the cornea and retina and arterioles and venules were clearly defined. Transscleral retinal imaging was achieved in albino animals. CONCLUSIONS: Ultrahigh-resolution, full-field OCT allows cellular-level imaging of unstained ocular tissues with high penetration depth. Although the current system is unsuitable for clinical use, this simple technique has potential for in vivo ocular examination, for which a new system is currently under development.

Fibered confocal fluorescence microscopy (Cell-viZio) facilitates extended imaging in the field of microcirculation. A comparison with intravital microscopy.

This study investigated the capability of fibered confocal fluorescence microscopy (FCFM) to provide in vivo microvascular observations. FCFM is specifically designed for in vivo in situ observation thanks to a probe composed of a fiber bundle and micro-optics having a diameter as small as 650 microm. In the first part of the study, we compared the main characteristics of FCFM with those of intravital fluorescence microscopy (IFM). A mouse cremaster preparation was used as a common basis to allow for imaging with both modalities. We discussed the feasibility of obtaining quantitative measurements usually provided by IFM in the context of FCFM: morphometry, capillary permeability, functional capillary density, vasoconstriction and dilation effects. In addition, the possibility to visualize fluorescent red blood cells or leukocytes was also evaluated. Phototoxicity issues and limitations of FCFM were also discussed. We showed that FCFM allows observations and measurements usually provided by IFM and that the real-time capability of the system, as well as the flexibility and small diameter of the optical probe enable micro-invasiveness and can extend imaging capabilities for in vivo in situ observations when compared to IFM.

ERGs in female carriers of incomplete congenital stationary night blindness (I-CSNB). A family report.

ERG findings in five sisters are reported. By pedigree analysis, four of the five must be obligate carriers for I-CSNB since their sons were affected (impaired night vision, reduced visual acuity, variable ametropia, congenital nystagmus and ERG with both scotopic and photopic b-wave reduced amplitude). The fifth was childless at the time of examination and her ERG analysis was normal. Three of the four obligate carriers showed significant reduction in the sum of the OPs amplitude as previously reported as being an electrophysiological signs in female carriers: two without alteration in other ERG components and the third with association with a flicker ERG amplitude significantly increased. The fourth female carrier showed a normal sum of the OPs amplitude whereas the other b-wave ERG or flicker amplitudes were significantly decreased. These last two ERG results suggest a possible modifications of synaptic transmission at a post-receptoral site (outer plexiform layer or involvement of the bipolar pathways) in these two carriers.

SLO angiography: arterio-venous filling times in monkey and minipig.

Confocal scanning laser ophthalmoscope (cSLO) is a new technique which enables ocular fundus image recording and dynamic retinal angiography to be performed. The ocular fundus image is acquired sequentially, point by point, and is reconstructed on a video monitor at the rate of 25 images per second. The aim of this paper is to evaluate the feasibility of measuring retinal arterio-venous filling times (AVFT) with a I + Tech cSLO. Three young adult cynomolgus monkeys and three young adult Göttingen minipigs were used as experimental models. All animals were anesthetized using a zolazepam + tiletamine mixture injected intramuscularly; heart rate and rectal temperature were monitored and corneal irrigation was regularly performed. For all subjects, prior to examination, hematocrit and globe axial length were measured. The images were recorded, stabilized and analyzed. The retinal examination consisted of retinal images with 40 degrees field cSLO, retinal fluorescein angiography and arterio-venous 50% filling time measurements. For each subject all images were easily recorded while keeping the animals in a normally lighted room without having to use any additional optical device. AVFT using an I + Tech cSLO is easily performed in monkeys and minipigs. AVFT measurements in minipigs and monkeys are similar. These results suggest that minipigs can replace monkeys as an experimental species for AVFT investigations.