Angiographic findings following tack fixation of a wireless epiretinal retina implant device in blind RP patients

BACKGROUND

The fixation of polyimide stimulator foils as the basic substrate of epiretinal prostheses by using retinal tacks may cause retinal or choroidal alterations such as retinal proliferations or choroidal neovascularizations. During the prospective trial for the semichronical testing of a wireless intraocular retinal implant (EPIRET3) we investigated alterations in angiographic findings during implantation and after explantation of the device, to detect potential vascular pathologies at the fixation site or elsewhere.

METHODS

As the final step of the implantation surgery in six blind patients, the stimulator was placed on the retinal surface using retinal tacks. For the detection of possible morphological or vascular alterations committed by the implant fluorescein angiography (FA) was performed 1 day before and 4 weeks after implantation surgery, as well as at the final visit 5 months after explantation.

RESULTS

Following implantation surgery funduscopy and FA did not reveal any evidence of either vascular pathologies or choroidal neovascularisations (CNV), in addition, no cystoid macular edema (CME) occurred after 4 weeks. At the 6-month follow-up visit, we found a mild epiretinal gliosis formation in four patients. In one patient a retinal break occurred during explantation, requiring a temporary silicone-oil endotamponade. At the final visit, we observed a focal proliferative vitreoretinopathy (PVR) reaction without activity, while there was no evidence for a CNV formation in that area.

CONCLUSIONS

The FA findings confirm our previous results on the safety of the EPIRET3 system, which was tolerated in all patients but revealed a certain risk profile in regard to the stimulator fixation. While there was no evidence for newly occurred CME or CNV during the follow-up visits, nevertheless gliosis or even PVR reaction at the tack's fixation site suggests the need to develop alternative fixation procedures of epiretinal stimulators.

[Contemporary possibilities of artificial vision in blind patients using artificial neuro-prosthesis--review]

The authors present the knowledge summarization of vision substitute using artificial retinal neuroprostheses. The overview was compiled from available literature found in the Medline and Embase databases. The text focuses on global summarizing of the whole issue since the beginning of the development to the state up to date. In individual types of neuroprostheses, the advantages, disadvantages, and possible obstacles to their use in clinical practice are discussed. Furthermore, the brain plasticity and functional changes of the brain in blinds are considered. The aim of the review is not to present all information in detail, but complex overview with relevant literature sources.

The impact of rope jumping exercise on physical fitness of visually impaired students

The main purpose of this study was to investigate the impact of rope jumping exercise on the health-related physical fitness of visually impaired students. The participants' physical fitness was examined before and after the training. The exercise intensity of the experimental group was controlled with Rating of Perceived Exertion (RPE) (values ranging from 11 to 15), while the control group did not participate in the exercise. A dependent samples t-test indicated significant differences in both groups between pre- and post-training. Through ANCOVA analysis, there was a significant difference (p<.05) in the flexibility and aerobic capacity for the experimental group and a significant improvement on their physical fitness (p<.05).

Persons with multiple disabilities use orientation technology to find room entrances during indoor traveling

These two studies assessed adapted orientation technology for promoting correct direction and room identification during indoor traveling by persons with multiple (e.g., sensory, motor and intellectual/adaptive) disabilities. In Study I, two adults were included who had severe visual impairment or total blindness and deafness and used a wheelchair for traveling. In Study II, two adults participated who had visual impairment or total blindness but were ambulatory. All participants were to travel to different rooms located along a hallway to carry out small activities. The orientation technology ensured that the participants received (a) a verbal instruction to go to their right or left and/or a vibratory cue to the right or left side of their body as soon as they exited a room to orient their travel within the hallway and (b) a similar verbal instruction and/or vibratory cue to turn and enter when they reached the next target room entrance. Results of both studies showed that the participants on wheelchairs and those able to ambulate were successful in using the technology, orient their travel, and find the appropriate room entrances. The findings are discussed in relation to the importance of independent indoor traveling and the impact of the new technology.

Ergonomic factors related to drop-off detection with the long cane: effects of cane tips and techniques

OBJECTIVE

This study examined the effect of cane tips and cane techniques on drop-off detection with the long cane.

BACKGROUND

Blind pedestrians depend on a long cane to detect drop-offs. Missing a drop-off may result in falls or collision with moving vehicles in the street. Although cane tips appear to affect a cane user's ability to detect drop-offs, few experimental studies have examined such effect.

METHOD

A repeated-measures design with block randomization was used for the study. Participants were 17 adults who were legally blind and had no other disabilities. Participants attempted to detect the drop-offs of varied depths using different cane tips and cane techniques.

RESULTS

Drop-off detection rates were similar between the marshmallow tip (77.0%) and the marshmallow roller tip (79.4%) when both tips were used with the constant contact technique, p = .294. However, participants detected drop-offs at a significantly higher percentage when they used the constant contact technique with the marshmallow roller tip (79.4%) than when they used the two-point touch technique with the marshmallow tip (63.2%), p < .001.

CONCLUSION

The constant contact technique used with a marshmallow roller tip (perceived as a less advantageous tip) was more effective than the two-point touch technique used with a marshmallow tip (perceived as a more advantageous tip) in detecting drop-offs.

APPLICATION

The findings of the study may help cane users and orientation and mobility specialists select appropriate cane techniques and cane tips in accordance with the cane user's characteristics and the nature of the travel environment.

Two persons with multiple disabilities use orientation technology with auditory cues to manage simple indoor traveling

This study was an effort to extend the evaluation of orientation technology for promoting independent indoor traveling in persons with multiple disabilities. Two participants (adults) were included, who were to travel to activity destinations within occupational settings. The orientation system involved (a) cueing sources only at the destinations (i.e., a single sound source per destination), (b) a newly developed electronic control device that allowed the participants to easily manage the activation of the sources at the destinations, and (c) the provision of approval or encouragement messages. Both participants were successful in using the system and performed their travels to the destinations fairly correctly and in relatively short amounts of time within (a) the occupational setting used for the intervention and (b) a similar occupational setting used for checking generalization effects. The findings are discussed in relation to the importance of independent indoor traveling and the impact of the new technology.

Blindness in childhood in developing countries: time for a reassessment?

Paul Courtright and colleagues argue that the changing patterns of global childhood blindness suggest a need to reassess research, training, and programmatic requirements.

SCORE Study Report 7: incidence of intravitreal silicone oil droplets associated with staked-on vs luer cone syringe design

PURPOSE

To evaluate the incidence of intravitreal silicone oil (SO) droplets associated with intravitreal injections using a staked-on vs luer cone syringe design in the SCORE (Standard Care vs COrticosteroid in REtinal Vein Occlusion) Study.

DESIGN

Prospective, randomized, phase III clinical trial.

METHODS

The incidence of intravitreal SO was compared among participants exposed to the staked-on syringe design, the luer cone syringe design, or both of the syringe designs in the SCORE Study, which evaluated intravitreal triamcinolone acetonide injection(s) for vision loss secondary to macular edema associated with central or branch retinal vein occlusion. Injections were given at baseline and 4-month intervals, based on treatment assignment and study-defined retreatment criteria. Because intravitreal SO was observed following injections in some participants, investigators were instructed, on September 22, 2006, to look for intravitreal SO at all study visits. On November 1, 2007, the luer cone syringe design replaced the staked-on syringe design.

RESULTS

A total of 464 participants received a total of 1,205 injections between November 4, 2004 and February 28, 2009. Intravitreal SO was noted in 141 of 319 participants (44%) exposed only to staked-on syringes, 11 of 87 (13%) exposed to both syringe designs, and 0 of 58 exposed only to luer cone syringes (P < .0001). Among participants with first injections after September 22, 2006, intravitreal SO was noted in 65 of 114 (57%) injected only with staked-on syringes compared with 0 of 58 injected only with luer cone syringes. Differential follow-up is unlikely to explain these results.

CONCLUSION

In the SCORE Study, luer cone syringe design is associated with a lower frequency of intravitreal SO droplet occurrence compared with the staked-on syringe design, likely attributable to increased residual space in the needle hub with the luer cone design.

Are current guidelines for categorization of visual impairment in India appropriate?

CONTEXT

Visual disability in India is categorized based on severity. Sometimes the disabled person does not fit unambiguously into any of the categories.

AIMS

To identify and quantify disability that does not fit in the current classification, and propose a new classification that includes all levels of vision.

SETTINGS AND DESIGN

Retrospective chart review of visual disability awarded in a teaching hospital.

MATERIALS AND METHODS

The last hundred records of patients who had been classified as visually disabled were screened for vision in both eyes and percentage disability awarded. Data were handled in accordance with the Helsinki Declaration.

RESULTS

Twenty-one patients had been classified as having 30% disability, seven each had 40% and 75%, and 65 had 100% disability. Eleven of them did not fall into any of the current categories, forcing the disability board to use its own judgment. There was a tendency to over-grade the disability (seven of 11; 63.6%). The classification proposed by us is based on the national program for control of blindness' definition of normal vision (20/20 to 20/60), low vision ( < 20/60 to 20/200), economic blindness ( < 20/200 to 20/400) and social blindness ( < 20/400). It ranges from the mildest disability (normal vision in one eye, low vision in the other) up to the most severe grade (social blindness in both eyes).

CONCLUSIONS

The current classification of visual disabilities does not include all combinations of vision; some disabled patients cannot be categorized. The classification proposed by us is comprehensive, progresses logically, and follows the definitions of the national program.

A wearable real-time image processor for a vision prosthesis

Rapid progress in recent years has made implantable retinal prostheses a promising therapeutic option in the near future for patients with macular degeneration or retinitis pigmentosa. Yet little work on devices that encode visual images into electrical stimuli have been reported to date. This paper presents a wearable image processor for use as the external module of a vision prosthesis. It is based on a dual-core microprocessor architecture and runs the Linux operating system. A set of image-processing algorithms executes on the digital signal processor of the device, which may be controlled remotely via a standard desktop computer. The results indicate that a highly flexible and configurable image processor can be built with the dual-core architecture. Depending on the image-processing requirements, general-purpose embedded microprocessors alone may be inadequate for implementing image-processing strategies required by retinal prostheses.

Index finger somatosensory evoked potentials in blind Braille readers

BACKGROUND AND PURPOSE

Traditionally, vision has been considered the dominant modality in our multi-sensory perception of the surrounding world. Sensory input via non-visual tracts becomes of greater behavioural relevance in totally blind individuals to enable effective interaction with the world around them. These include audition and tactile perceptions, leading to an augmentation in these perceptions when compared with normal sighted individuals. The objective of the present work was to study the index finger somatosensory evoked potentials (SEPs) in totally blind and normal sighted individuals.

MATERIAL AND METHODS

SEPs were recorded in 15 Braille reading totally blind females and compared with 15 age-matched normal sighted females. Latency and amplitudes of somatosensory evoked potential waveforms (N9, N13, and N20) were measured.

RESULTS

Amplitude of N20 SEP (a cortical somatosensory evoked potential) was significantly larger in the totally blind than in normal sighted individuals (p < 0.05). The amplitudes of N9 and N13 SEP and the latencies of all recorded SEPs showed no significant differences.

CONCLUSIONS

Blindness has a profound effect on the Braille reading right index finger. Totally blind Braille readers have larger N20 amplitude, suggestive of greater somatosensory cortical representation of the Braille reading index finger.

Cataract blindness in Chakwal District, Pakistan: Results of a survey

AIM

To present the results of a rapid assessment of cataract surgical services in Chakwal District, Pakistan.

METHODS

40 clusters of 40 persons of 50 years and older (1600 eligible persons) were selected by systematic random sampling from the entire Chakwal district. A total of 1505 persons were examined (coverage 94%).

RESULTS

Cataract is the major cause of bilateral blindness (46.5%). The age and sex adjusted prevalence of bilateral cataract blindness (VA < 3/60) in people of 50 years and older was 2.0% (95% CI: 1.2-3.2%), with a cataract surgical coverage of 92% for males and 73% for females, a significant difference. The prevalence of bilateral cataract and VA < 6/60 in persons of 50 years and older was 5.1% (95% CI: 3.6-6.9), an estimated total of 8833 persons. In this last group, the surgical coverage was 66% (persons) and 50% (eyes). Of the patients operated with IOL implantation, 12% could not see 6/60, while 36% of those operated without IOL could not see 6/60. 'No services' (18%) and 'cannot afford' (18%) were mentioned most as reasons why surgery had not been done, followed by 'no information' (13%), 'waiting for maturity' (12%) and 'old age, no need for surgery' (12%).

CONCLUSION

The number of cataract operations in Chakwal District can be increased by reducing the threshold for cataract surgery to VA < 6/60 or less. A special approach to operate more females may be required. Results from this survey can be used for a planning exercise to optimize eye care services in the district. Sustained efforts have to be made to increase the number of IOL surgeries, through making IOL surgery available locally at an affordable cost.

A relative access measure to identify barriers to efficient transit use by persons with visual impairments

PURPOSE

Persons with visual impairments or blindness can face significant restrictions to their efficient travel, especially when attempting transit transfers and using a large, multi-modal terminal. Little is known about what makes some tasks much harder than others. This paper presents an approach to empirically measure the difficulty of a variety of transit tasks.

METHOD

An experiment was conducted at an urban transit terminal, with three other transit modes nearby. Thirty persons with visual impairments attempted to make five simulated transfers between these modes. Errors and time to complete these tasks were collected in order to quantify the nature of various barriers to efficient travel for this group. In total, 20 locations were visited. Completion times were compared to a sighted traveler to determine a measure of the time penalty, or 'relative access measure.'

RESULTS

Two basic findings are reported. Empirical data showed that different types of transit tasks and locations had a wide range of difficulty and inherent time penalties. Some tasks like crossing a difficult street, finding unmarked track doors, and finding inconsistently placed amenities were quite time consuming and sometimes impossible to accomplish. Other tasks, like walking to a street corner and crossing a simpler street, had much lower penalties and could be completed with ease.

CONCLUSIONS

The placement of additional cues, those of identity and direction, provided with auditory signage, were able to eliminate much of the uncertainty and time restrictions associates with transit use and navigation for persons with visual impairments.

[Artificial vision for the human blind]

Since 1960 many attempts have been made to develop visual prostheses for the blind; most of the devices based on the production of phosphenes through electrical stimulation with microelectrodes at the retina, optic nerve, lateral geniculate or occipital lobe are incapable to reconstruct a coherent retinotopic map (coordinate match between the image and the visual perception of the patient); furthermore they display important restrictions at the biomaterial level that hinder their final implantation through surgical techniques which at present time offers more risks than benefits to the patient. Considering the new theories about intermodal perception it is possible the acquisition of visual information through other senses; The Micromechanics and Mecatronics Group (GMM) from The Center of Applied Sciences and Technological Development at The National Autonomous University of Mexico by this paper, describes the experimental design and psychophysical data necessary for the construction of a visual sensory substitution prostheses with a vibrotactile system. The vibrotactile mechanism locates different bars over the epidermis in a predetermined way to reproduce a point by point matrix order in a logical sequence of rows and columns that allow the construction of an image with an external device that not require invasive procedures.

One hundred and twenty visually handicapped children below 7 years of age

120 visually handicapped pre-school children are evaluated according to eye disease and its etiology, and the associated handicap, all related to the different levels of functioning. One third of the children fulfil the expectations on visually handicapped children. The group consists mainly of children suffering from hereditary ocular disorders and some children with retrolental fibroplasia. One third of the children are moderately or severely intellectually impaired, bearing a heavy burden of additional handicaps; many are born premature or dysmature, having suffered perinatal complications. The final third are children who fall outside the other 2 groups, some with a brain damage syndrome, some with light or moderate behavioural and emotional disturbance. The moderate and severe emotional disturbance and its relation to a brain dysfunctional syndrome are discussed.

SoundView: an auditory guidance system based on environment understanding for the visually impaired people

Without visual information, the blind people live in various hardships with shopping, reading, finding objects and etc. Therefore, we developed a portable auditory guide system, called SoundView, for visually impaired people. This prototype system consists of a mini-CCD camera, a digital signal processing unit and an earphone, working with built-in customizable auditory coding algorithms. Employing environment understanding techniques, SoundView processes the images from a camera and detects objects tagged with barcodes. The recognized objects in the environment are then encoded into stereo speech signals for the blind though an earphone. The user would be able to recognize the type, motion state and location of the interested objects with the help of SoundView. Compared with other visual assistant techniques, SoundView is object-oriented and has the advantages of cheap cost, smaller size, light weight, low power consumption and easy customization.

Honors biomedical instrumentation--a course model for accelerated design

A model for a 16-week Biomedical Instrumentation course is outlined. The course is modeled in such a way that students learn about medical devices and instrumentation through lecture and laboratory sessions while also learning basic design principles. Course material covers a broad range of topics from fundamentals of sensors and instrumentation, guided laboratory design experiments, design projects, and eventual protection of intellectual property, regulatory considerations, and entry into the commercial market. Students eventually complete two design projects in the form of a 'Challenge' design project as well as an 'Honors' design project. Sample problems students solve during the Challenge project and examples of past Honors projects from the course are highlighted.

[Somatosensoric prosthesis for the blind]

At present vision prosthesis proposes transmission of only a limited amount of visual information. Cutaneous receptor field may serve as a information channel. It has similar information-processing ability as retina. Lower information capacity of the skin may be compensated by wavelet transform image compression. Advances in microtechnology have facilitated the development of a haptic data visualization system with sufficient life-time for people with visual impairments. Proposed array with 2400 carbon electrodes stewed on elastic membrane in the present experiments demonstrate a good mechanical endurance, electrical stability and adhesivity to the trunk skin. Disadvantageous is short circuits production among near electrodes due to sweating and skin irritation after long term electrical stimulation. Vibrotactile piezo-electric stimulators are safer alternative with lower resolution. Comparing retinal and cortical vision prosthesis offers electrocutaneous communication system comparably higher amount of transmitted information.