Graph-Based Multi-Surface Segmentation of OCT Data Using Trained Hard and Soft Constraints

Optical coherence tomography (OCT) is a well-established image modality in ophthalmology and used daily in the clinic. Automatic evaluation of such datasets requires an accurate segmentation of the retinal cell layers. However, due to the naturally low signal to noise ratio and the resulting bad image quality, this task remains challenging. We propose an automatic graph-based multi-surface segmentation algorithm that internally uses soft constraints to add prior information from a learned model. This improves the accuracy of the segmentation and increase the robustness to noise. Furthermore, we show that the graph size can be greatly reduced by applying a smart segmentation scheme. This allows the segmentation to be computed in seconds instead of minutes, without deteriorating the segmentation accuracy, making it ideal for a clinical setup. An extensive evaluation on 20 OCT datasets of healthy eyes was performed and showed a mean unsigned segmentation error of 3.05 ±0.54 μm over all datasets when compared to the average observer, which is lower than the inter-observer variability. Similar performance was measured for the task of drusen segmentation, demonstrating the usefulness of using soft constraints as a tool to deal with pathologies.

Prevention of increased abnormal fundus autofluorescence with blue light-filtering intraocular lenses

PURPOSE To observe changes in fundus autofluorescence 2 years after implantation of blue light-filtering (yellow-tinted) and ultraviolet light-filtering (colorless) intraocular lenses (IOLs). SETTING Department of Ophthalmology and Visual Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan, and the Department of Ophthalmology, University of Bern, Bern, Switzerland. DESIGN Prospective comparative observational study. METHODS Patients were enrolled who had cataract surgery with implantation of a yellow-tinted or colorless IOL and for whom images were obtained on which the fundus autofluorescence was measurable using the Heidelberg Retina Angiogram 2 postoperatively. The fundus autofluorescence in the images was classified into 8 abnormal patterns based on the classification of the International Fundus Autofluorescence Classification Group, The presence of normal fundus autofluorescence, geographic atrophy, and wet age-related macular degeneration (AMD) also was recorded. The fundus findings at baseline and 2 years postoperatively were compared. RESULTS Fifty-two eyes with a yellow-tinted IOL and 79 eyes with a colorless IOL were included. Abnormal fundus autofluorescence did not develop or increase in the yellow-tinted IOL group; however, progressive abnormal fundus autofluorescence developed or increased in 12 eyes (15.2%) in the colorless IOL group (P = .0016). New drusen, geographic atrophy, and choroidal neovascularization were observed mainly in the colorless IOL group. The incidence of AMD was statistically significantly higher in the colorless IOL group (P = .042). CONCLUSIONS Two years after cataract surgery, significant differences were seen in the progression of abnormal fundus autofluorescence between the 2 groups. The incidence of AMD was lower in eyes with a yellow-tinted IOL. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned.

ABCA4 and ROM1: Implications for modification of the PRPH2-associated macular dystrophy phenotype

To identify the causative mutation leading to autosomal dominant macular dystrophy, cone dystrophy, and cone-rod dystrophy in a five-generation family and to explain the high intrafamilial phenotypic variation by identifying possible modifier genes.

The ocular motor features of adult-onset alexander disease: a case and review of the literature

A 51-year-old Chinese man presented with gaze-evoked nystagmus, impaired smooth pursuit and vestibular ocular reflex cancellation, and saccadic dysmetria, along with a family history suggestive of late-onset autosomal dominant parkinsonism. MRI revealed abnormalities of the medulla and cervical spinal cord typical of adult-onset Alexander disease, and genetic testing showed homozygosity for the p.D295N polymorphic allele in the gene encoding the glial fibrillary acidic protein. A review of the literature shows that ocular signs are frequent in adult-onset Alexander disease, most commonly gaze-evoked nystagmus, pendular nystagmus, and/or oculopalatal myoclonus, and less commonly ptosis, miosis, and saccadic dysmetria. These signs are consistent with the propensity of adult-onset Alexander disease to cause medullary abnormalities on neuroimaging.

Caspase-3-independent photoreceptor degeneration by N-methyl-N-nitrosourea (MNU) induces morphological and functional changes in the mouse retina

Retinal degeneration is followed by significant changes in the structure and function of photoreceptors in humans and several genetic animal models. However, it is not clear whether similar changes occur when the degeneration is induced pharmacologically. Therefore, our aim was to investigate the influence of retinotoxic N-methyl-N-nitrosourea (MNU) on the function, morphology and underlying molecular pathways of programmed cell death.

The effects of a flexible visual acuity-driven ranibizumab treatment regimen in age-related macular degeneration: outcomes of a drug and disease model

Differences in treatment responses to ranibizumab injections observed within trials involving monthly (MARINA and ANCHOR studies) and quarterly (PIER study) treatment suggest that an individualized treatment regimen may be effective in neovascular age-related macular degeneration. In the present study, a drug and disease model was used to evaluate the impact of an individualized, flexible treatment regimen on disease progression.

Outcomes following three-line vision loss during treatment of neovascular age-related macular degeneration: subgroup analyses from MARINA and ANCHOR

This study aims to assess the impact of continued ranibizumab treatment for neovascular age-related macular degeneration on patients from the MARINA and ANCHOR randomised clinical studies who lost ≥ 3 lines of best-corrected visual acuity (BCVA) at any time during the first year of treatment.

Retinal vascular occlusion after vitrectomy with retrobulbar anesthesia-observational case series and survey of literature

BACKGROUND: Severe postoperative loss of vision has been occasionally reported as a rare complication of retrobulbar anesthesia, and several possible causes have been proposed in the literature. In this work, our own and other investigators' experiences with these complications are surveyed with a view to identifying its pathophysiology. PATIENTS: This observational case series refers to six patients who presented during a 3-month period with occlusion of either the central artery itself (n = 3) or a branch thereof (n = 3) 2-14 days after uneventful vitreoretinal surgery following retrobulbar anesthesia with a commercial preparation of mepivacaine (1% Scandicain®, Astra Chemicals, Sweden) containing methyl- and propyl parahydroxybenzoate as preservatives. RESULTS: Three of the patients carried risk factors, which were medically controlled. In three individuals, vasoocclusion was observed after a second vitreoretinal intervention, which was performed 3-12 months after uneventful primary surgery. Good visual recovery was observed in only one instance. CONCLUSIONS: In patients who were anesthetized with preservative-free mepivacaine, no vasoocclusion occurred. In individuals who were anesthetized with mepivacaine containing the preservatives methyl- and propyl parahydroxybenzoate, a tenfold increase in the incidence of eyes requiring re-operation was documented, with a 2- to 14-day lapse in the onset of vasoocclusion. These findings reveal a possible implication of preservatives contained in the local anesthetic solution for the vasoocclusive events. Due to this potential hazard, the use of preservative-free preparations of local anesthesia in ocular surgery is emphasized in order to prevent this sight-threatening complication.

Repeatability of nerve fiber layer thickness measurements in patients with glaucoma and without glaucoma using spectral-domain and time-domain OCT

The aim of this work is to assess the repeatability of spectral-domain-OCT (SD-OCT) retinal nerve fiber layer thickness (RNFL) thickness measurements in a non-glaucoma group and patients with glaucoma and to compare these results to conventional time-domain-OCT (TD-OCT).

Cataract and cognitive impairment: a review of the literature

Acquired cataract and cognitive impairment are both common age-related problems, and ophthalmologists are increasingly likely to encounter patients who have both. Patients with dementia types who display early visuoperceptual impairment may present first to ophthalmology services. When these patients have coexisting cataract, it may be difficult to distinguish visual complaints due to cataract from those due to dementia. The interaction between visual impairment due to cataract and neurodegenerative disorders affecting the central visual pathways, is not fully understood. Visual impairment due to cataract may stress impaired attentional mechanisms and cataract extraction may improve cognitive performance in some patients with early cognitive impairment; however, the benefits of cataract surgery in established dementia are less clear. In this study, the literature on this subject was reviewed and the implications for practice were considered.

Compliance and knowledge about glaucoma in patients at tertiary glaucoma units

To document the rate of self-reported compliance and glaucoma-related knowledge in Swiss patients and to identify risk factors for their poor compliance. This was an observational study, including a total of 200 consecutive patients already under glaucoma medication in two Swiss tertiary glaucoma clinics (Geneva and Bern). Personal characteristics, presence of systemic disease, compliance with glaucoma medication, attitude to the ophthalmologist, and glaucoma-related attitudes were ascertained by means of a predetermined questionnaire with 40 questions. Patients were subsequently assessed for the ability to correctly instil placebo eye drops. Non-compliance with glaucoma medication was defined as omitting more than two doses a week as reported by the patient. Logistic regression was used to evaluate how patient characteristics and knowledge about the disease were related to compliance. Overall, 81% (n = 162) of patients reported to be compliant. Forgetfulness was the most frequently cited reason for non-compliance with dosing regimen (63%). Although 90.5% (n = 181) of patients believed glaucoma medication to be efficient, only 28% (n = 56) could correctly define glaucoma. Factors positively associated with compliance were 'knowledge of glaucoma' [adjusted odds ratio (OR) 4.77 (95% CI 1.36-16.70)] and 'getting help for administration of drops' [OR 2.95 (1.25-6.94)]. These findings indicate that despite the comparatively high compliance rate among glaucoma patients, knowledge of glaucoma remains poor in long-term glaucoma sufferers. Improving knowledge about the disease is important since it is positively associated with compliance in our study.