Prostaglandin E1 infusion therapy in dry age-related macular degeneration

OBJECTIVE: The pilot study is intended to show whether prostaglandin E1 (PGE1) infusions are able to stop the gradual vision loss in dry age-related macular degeneration (AMD) and, further, to stabilize or improve visual acuity. METHODS: With PGE1 infusions 11 patients with different forms of dry AMD were treated and compared with a control group of 10 untreated patients with dry AMD. The target parameter was the visual acuity, as determined with the ETDRS logMAR charts. Other examinations performed during the study were tests of contrast vision, colour vision and central visual fields, as well as autofluorescence and fluorescein angiography and multifocal electroretinography. RESULTS: On termination of the infusions, six patients showed an increase in visual acuity by at least one line, an improvement that was seen in eight patients 2 months after the end of the infusion therapy. After 6 months, one patient exhibited an improvement of visual acuity by three lines and three patients an improvement by one line. Five patients were found to show no change of their baseline acuity values after 6 months, while two patients exhibited an impairment by one line. The visual acuity in the dry AMD control group without PGE1 treatment had decreased by 0.8 lines on the average after 6 months. Contrast vision, central visual fields and the multifocal electroretinogram showed improvements on the termination of infusions and up to 2 months later; no substantial change of these parameters, as compared with the baseline findings, was seen 6 months after the termination of infusions. SUMMARY: This pilot study suggests that PGE1 infusions have a stabilizing or improving effect on the visual acuity of patients with dry AMD. Owing to the limitations of a pilot study, these results should, however, be validated in a larger, randomized and blinded study.     

Association of contrast sensitivity with LogMAR visual acuity and glycosylated hemoglobin in non-insulin dependent diabetes mellitus

A tertiary care center-based prospective case–control study was undertaken to evaluate the association of contrast sensitivity with LogMAR visual acuity and glycosylated hemoglobin (HbA1c) in 205 cases of non-insulin dependent diabetes mellitus and 115 controls. LogMAR visual acuity and contrast sensitivity were scored using ETDRS and Pelli-Robson charts, respectively. Bivariate correlation between contrast sensitivity and LogMAR visual acuity showed significant inverse correlation in cases without retinopathy (r = −0.466) and with non-proliferative retinopathy (r = −0.307). In a multivariate model, on applying linear regression analysis, LogMAR visual acuity (p < 0.001) and HbA1c (p = 0.002) had significant association with contrast sensitivity. Significant difference in contrast sensitivity was not observed between cases without diabetic retinopathy and with non-proliferative diabetic retinopathy, implying no association with retinal microvascular changes. Contrast sensitivity dysfunction observed in diabetes mellitus results from changes in retinal function secondary to alteration in carbohydrate metabolism depicted in glycosylated hemoglobin.     

Visual acuity and hyperacuity in 11- to 17-year-old secondary school students

Visual acuity and hyperacuity of 11- to 17-year-old secondary school students with normal vision were measured and compared. The estimations of hyperacuity and acuity were made using the vernier stimuli, Landolt Cs, and Tumbling Es. When test stimuli were located in the tables, visual acuity estimations measured using Landolt Cs were significantly higher by a factor of 1.1 than that measured using Tumbling Es. Visual hyperacuity was 1.25?C4.1 times higher than visual acuity. The estimations of visual hyperacuity were almost 2 times higher in 16-year-old than 13-year-old secondary school students, in contrast to the estimations of visual acuity that did not change with age. The binocular visual acuity estimations were 1.05 times higher than the monocular ones and did not depend on the age. The ratio of binocular visual hyperacuity to monocular visual hyperacuity in 13-year-old secondary school students was 1.9, whereas, in senior secondary school students, it was 1.2. The contribution of binocular vision to the development of the mechanisms of visual acuity and hyperacuity in ontogenesis and the differences between the mechanisms of visual acuity and hyperacuity are discussed.     

Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices

Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc.) and three ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off) exceeded the most stringent requirement for mean luminance (≥ 120 cd/m²) providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90%) regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (L_min/L_max ≥ 80%). Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off) had adequate mean luminance (≥ 120 cd/m²) and Weber contrast (≥ 90%), but all three charts failed to meet the luminance uniformity standard (L_min/L_max ≥ 80%). Two charts were operating beyond manufacturer’s recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out-performed ETDRS charts in terms of photometric compliance with high contrast acuity standards.     

Factors Affecting Reading Speed in Patients with Diabetic Macular Edema Treated with Laser Photocoagulation

Purpose

To study the factors that may affect reading speed in patients with diabetic macular edema previously treated with laser photocoagulation.

Methods

Consecutive patients with type II diabetes treated with laser photocoagulation for diabetic macular edema (DME) at least twelve months previously, with best corrected visual acuity of better than 65 letters (approximately 20/40) measured with Early Treatment Diabetic Retinopathy Study (ETDRS) charts were included in this study. Patients previously treated with pan-retinal photocoagulation, vitrectomy, intravitreal steroid or anti-VEGF therapy were excluded. Any other ocular co-morbidities that may influence reading ability such as cataract, glaucoma or macular degeneration were also excluded. All patients were refracted by a certified examiner, the following measurements were collected: best corrected visual acuity (BCVA), contrast sensitivity with Pelli-Robson chart, reading speed with MNREAD chart, microperimetry with Nidek MP1, and central subfield thickness with Zeiss spectral domain optical coherent topography.

Results

The slow reading group had poorer contrast sensitivity (p = 0.001), reduced retinal sensitivity (p = 0.027) and less stable fixation (p = 0.013). Most interestingly the reduced retinal sensitivity findings were driven by the microperimetry value on the right subfield (p = 0.033), (nasal to the fovea in the right eye and temporal to the fovea in the left eye). Multiple linear regression analysis showed that contrast sensitivity is probably the most important factor that affects reading speed (p = 0.001).

Conclusion

Reduced retinal sensitivity after laser treatment is associated with reduced reading speed in patients with diabetic macular edema.     

人工视觉辅助系统：现状与展望

通过视觉获取图像信息是人类学习和生活的重要功能,失明则会显著降低其生活质量. 因视网膜色素变性、青光眼和黄斑变性等疾病而造成后天失明者,以及由意外事故、战争等造成眼部创伤者,有可能通过人工视觉辅助系统的帮助恢复部分视觉,或者完成复杂的生活任务. 一些盲症患者视觉通路的神经传导剩余部分依然有功能,因此可以借助电极阵列刺激视神经向大脑传递视觉信息,也可在大脑视觉皮层贴敷电极阵列的方法输入视觉信息. 此外,还能借助体外装置,如通过人工智能将视觉转换成语音指令、触觉阵列编码等,帮助盲症患者获得环境信息. 本文综述各类人工视觉辅助系统的现状,展望其发展趋势,并提出了新的植入器件与随身体外装置的新设想.     

Changes of Vision-Related Quality of Life in Retinal Detachment Patients after Cataract Surgery

Rhegmatenous retinal detachment (RRD) is one of the most serious complications after phacoemulsification combined with intraocular lens implantation surgery. It has been reported that vision-related quality of life (VRQoL), as well as visual acuity rapidly decreased when RRD developed. However, little is known of the VRQoL in those RRD patients after anatomical retinal re-attachment, especially whether or not the VRQoL is higher than that before cataract surgery. In this prospective case series study, we use the Chinese-version low vision quality of life questionnaire (CLVQOL) to assess the changes of VRQoL in age-related cataract patients who suffered from RRD after phacoemulsification with intraocular lens (phaco-IOL) implantation. All participants were asked to complete questionnaires in face- to-face interviews one day before and two weeks after cataract surgery, as well as one day before and three months after RRD surgery. A total of 10,127 consecutive age-related cataract patients were followed up to one year after phaco-IOL implantation; among these patients, 17 were diagnosed as RRD. The total CLVQOL scores and subscale scores except “Mobility” decreased significantly when RRD developed. After retinal surgery, only the score of “General vision and lighting” in the CLVQOL questionnaires improved when compared to the scores two weeks after cataract surgery, although the best corrected visual acuity of all patients significantly raised up. However, the mean CLVQOL scores and subscale scores were still considerably higher than the level prior to cataract surgery. Our study suggests that cataract patients at high risk of postoperative RRD should not deny the opportunity to undergo phaco-IOL implantation, even though potential VRQoL impairment induced by RRD exists.     

Endogenous Fusarium Endophthalmitis During Treatment for Acute Myeloid Leukemia,Successfully Treated with 25-Gauge Vitrectomy and Antifungal Medications

Endogenous fungal endophthalmitis (EFE) caused by disseminated fusariosis is a rare condition that generally has a poor outcome, even with intensive therapy. Here, we describe a case in which this type of EFE was diagnosed with vitreous sampling and was successfully treated with 25-gauge vitrectomy and antifungals, including liposomal amphotericin B and voriconazole. A 16-year-old male patient undergoing treatment for acute myeloid leukemia complained of eye pain and blurred vision in his right eye. Treatment was initiated for a vitreous opacity, possibly associated with herpetic retinitis, but the patient worsened and he was referred to us. Right-eye visual acuity was limited to light perception. We suspected endogenous endophthalmitis and performed 25-gauge vitrectomy with antibiotic perfusion of ceftazidime, vancomycin, and voriconazole. Vitreous culturing revealed the presence of Fusarium solani species complex, and enhanced computed tomography revealed disseminated fusariosis lesions in the lung, spleen, and the soft tissue of the left upper arm. The patient received antifungal treatment with liposomal amphotericin B and voriconazole, and these conditions were eliminated. Visual acuity recovered to 20/400 after additional vitrectomy for tractional retinal detachment and was maintained at this level during the 6-month follow-up period. The success of our treatment allowed the capture of optical coherence tomography images of the retina during fusarium-associated endogenous endophthalmitis and the follow-up period. Furthermore, this case showed that immediate vitrectomy for suspected EFE and intensive treatment can lead to a good clinical outcome.     

Wavelength dependence of visual acuity in goldfish

Visual acuity was measured in a two-choice training experiment with food reward. Four goldfish were trained to select a homogeneously illuminated testfield when a high-contrast grating (transparancy) was shown for comparison at the second testfield. Measurements were performed for white and monochromatic testfield illuminations in the light adapted state. Fourteen wavelengths between 404 nm and 683 nm were tested. For each wavelength (and white light) the testfield intensity was determined for which spatial resolution was highest. Between 446 nm and 683 nm maximal values of 2.0 cycles/deg (corresponding to a visual acuity of 15' of arc) were found. At 404 nm and in the ultraviolet resolution was lower (0.6 and ~0.25–0.35 cycles/deg, respectively). Cone and small ganglion cell densities may equally account for visual acuity. The action spectrum of maximal visual acuity is very similar to the spectral sensitivity function representing recognition of "colour". Measurements under reduced room illumination and after treatment with Ethambutol further indicate that the detection of high contrast gratings is processed by the same "channel" as colour vision. A similar separate and parallel processing of "colour" and "form" on the one hand, and "brightness" and "motion" on the other hand was found in humans.     

Visual Function and Cortical Organization in Carriers of Blue Cone Monochromacy

Carriers of blue cone monochromacy have fewer cone photoreceptors than normal. Here we examine how this disruption at the level of the retina affects visual function and cortical organization in these individuals. Visual resolution and contrast sensitivity was measured at the preferred retinal locus of fixation and visual resolution was tested at two eccentric locations (2.5° and 8°) with spectacle correction only. Adaptive optics corrected resolution acuity and cone spacing were simultaneously measured at several locations within the central fovea with adaptive optics scanning laser ophthalmoscopy (AOSLO). Fixation stability was assessed by extracting eye motion data from AOSLO videos. Retinotopic mapping using fMRI was carried out to estimate the area of early cortical regions, including that of the foveal confluence. Without adaptive optics correction, BCM carriers appeared to have normal visual function, with normal contrast sensitivity and visual resolution, but with AO-correction, visual resolution was significantly worse than normal. This resolution deficit is not explained by cone loss alone and is suggestive of an associated loss of retinal ganglion cells. However, despite evidence suggesting a reduction in the number of retinal ganglion cells, retinotopic mapping showed no reduction in the cortical area of the foveal confluence. These results suggest that ganglion cell density may not govern the foveal overrepresentation in the cortex. We propose that it is not the number of afferents, but rather the content of the information relayed to the cortex from the retina across the visual field that governs cortical magnification, as under normal viewing conditions this information is similar in both BCM carriers and normal controls.     

Melanopsin regulates visual processing in the mouse retina

The discovery of melanopsin-dependent inner retinal photoreceptors in mammals has precipitated a fundamental reassessment of such non-image forming (NIF) light responses as circadian photoentrainment and the pupil light reflex. By contrast, it remains unclear whether these new photoreceptors also play a role in classical image-forming vision. The retinal ganglion cells that subserve inner retinal photoreception (ipRGCs) project overwhelmingly to brain areas involved in NIF responses, indicating that, in terms of central signaling, their predominant function is non-image forming. However, ipRGCs also exhibit intraretinal communication via gap junction coupling, which could allow them to modulate classical visual pathways within this tissue. Here, we explore this second possibility by using melanopsin knockout (Opn4-/-) mice to examine the role of inner retinal photoreceptors in diurnal regulation of retinal function. By using electroretinography in wild-type mice, we describe diurnal rhythms in both the amplitude and speed of the retinal cone pathway that are a function of both prior light exposure and circadian phase. Unexpectedly, loss of the melanopsin gene abolishes circadian control of these parameters, causing significant attenuation of the diurnal variation in cone vision. Our results demonstrate for the first time a melanopsin-dependent regulation of visual processing within the retina, revealing an important function for inner retinal photoreceptors in optimizing classical visual pathways according to time of day.     

Postoperative Vision-Related Quality of Life in Macula-Off Rhegmatogenous Retinal Detachment Patients and Its Relation to Visual Function

Objective

To determine the vision-related quality of life (VR-QOL) after surgery for macula-off rhegmatogenous retinal detachment (RRD) in relation to visual acuity, contrast acuity, and color vision.

Methods

In a prospective observational study, we included 55 patients with a macula-off RRD. Best corrected visual acuity (BCVA), color vision (saturated and desaturated color confusion indices (CCI)) and contrast acuity were measured at 12 months postoperatively in both the RRD eye and the fellow control eye, and the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) was filled out.

Results

Operated and fellow control eyes differed significantly in mean LogMAR BCVA (P<0.0001), median Log contrast acuity (P<0.0001), saturated CCI (P = 0.009), and desaturated CCI (P = 0.016). Significant correlations were observed between the NEI VFQ-25 overall composite score and postoperative LogMAR BCVA (R = −0.551, P<0.0001), contrast acuity (R = 0.472, P<0.0001), saturated CCI (R = −0.315, P = 0.023), and desaturated CCI (R = −0.283, P = 0.044).

Conclusions

A lower VR-QOL was highly correlated to a worse postoperative BCVA and contrast acuity and to a lesser extent to color vision disturbances.     

Streptokinase in central retinal vein occlusion: a controlled clinical trial.

Forty patients with central retinal vein occlusion were allocated at random either to a treatment group given streptokinase followed by anticoagulatns or to a control group given no specific treatment. The two groups, which were each of 20 patients, were broadly similar in respect of clinical and laboratory values and similar in their initial visual acuity. At follow-up ("final" vision) the visual acuity in the treated group was significantly better than in the untreated group. Only one treated patient developed thrombotic glaucoma compared with four controls. Streptokinase may, however, have been responsible for vitreous haemorrhage (and permanent loss of vision) in three patients and hence probably has only a limited role in the treatment of central retinal vein occlusion.     

Effects of cortical damage on binocular depth perception

Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local regions of the visual field and integration with other cues to depth. The most common cause for loss of stereoscopic vision is amblyopia, in which one eye has failed to form an adequate input to the visual cortex, usually due to strabismus (deviating eye) or anisometropia. However, the significant cortical processing required to produce the percept of depth means that, even when the retinal input is intact from both eyes, brain damage or dysfunction can interfere with stereoscopic vision. In this review, I examine the evidence for impairment of binocular vision and depth perception that can result from insults to the brain, including both discrete damage, temporal lobectomy and more systemic diseases such as posterior cortical atrophy.This article is part of the themed issue ‘Vision in our three-dimensional world’.     

Vision Loss and Psychological Distress among Ethiopians Adults: A Comparative Cross-Sectional Study

Background

Vision loss causes major changes in lifestyle and habits that may result in psychological distress and further reduction in the quality of life. Little is known about the magnitude of psychological distress in patients with vision loss and its variation with the normal. The aim of this study is, therefore, to investigate the psychological effects of vision loss and its determinants among Ethiopians.

Methods

A comparative cross-sectional study was conducted on adults attending the Eye clinic of Jimma University Hospital. One hundred fifteen consecutive adults with visual loss at least in one eye and 115 age-and sex-matched controls with normal vision were studied. The psychological distress was measured using standardized Self-Reporting Questionnaire (SRQ-20). Chi-square test and logistic regression were carried out and associations were considered significant at P<0.05.

Results

The overall prevalence of psychological distress was 33.4%. While psychological distress was found in 49.8% of patients who had loss of vision at least in one eye, only 18.3% of the controls had it. In the adjusted analysis, patients with vision loss had 4.6 times higher risk of suffering from psychological distress compared to patients with normal vision (AOR 4.56; 95% CI 2.16-9.62). Moreover, patients with vision loss in both eyes (AOR 4.00; 95% CI 1.453-11.015) and with worse visual acuity in the better eye (AOR 3.66; 95% CI 1.27-10.54) were significantly more likely to have psychological distress than those patients with vision loss in one eye only and good visual acuity in the better eye respectively. The cause of visual loss, pattern of visual loss, duration of visual loss and sociodemographic variables did not influence the likelihood of having psychological distress.

Conclusion

Prevalence of psychological distress was significantly higher in patients with visual loss compared to patients with normal vision. There is a need for integration of psychosocial care into the current medical and surgical treatment of patients with vision loss.     

Visual pigment bleaching in isolated salamander retinal cones. Microspectrophotometry and light adaptation

Visual pigment bleaching desensitizes rod photoreceptors greatly in excess of that due to loss of quantum catch. Whether this phenomenon also occurs in cone photoreceptors was investigated for isolated salamander red-sensitive cones. In parallel experiments, (a) visual pigment depletion by steps of bleaching light was measured by microspectrophotometry, and (b) flash sensitivity was measured by recording light-sensitive membrane current. In isolated cones, visual pigment bleaching permanently reduced flash sensitivity significantly below that due to the reduction in quantum catch, and there was little spontaneous recovery of visual pigment. The "extra" desensitization due to bleaching was most prominent up to bleaches of approximately 80% visual pigment and reached a level approximately 1 log unit beyond that due to loss of quantum catch. At higher bleaches, the effect of loss of quantum catch became more important. Bleaching did not greatly reduce the maximum light-suppressible membrane current. A 99% reduction of the visual pigment permanently reduced the circulating current by only 30%. Visual pigment bleaching speeded up the kinetics of dim flash responses. All electrical effects of bleaching were reversed on exposure to 11-cis retinal, which probably caused visual pigment regeneration. Light adaptation in photopic vision is known to involve significant visual pigment depletion. The present results indicate that cones operate with a maintained circulating current even after a large pigment depletion. It is shown how Weber/Fechner behavior may still be observed in photopic vision when the contributions of bleaching to adaptation are included.     

THE VISUAL ACUITY AND INTENSITY DISCRIMINATION OF DROSOPHILA

Drosophila possesses an inherited reflex response to a moving visual pattern which can be used to measure its capacity for intensity discrimination and its visual acuity at different illuminations. It is found that these two properties of vision run approximately parallel courses as functions of the prevailing intensity. Visual acuity varies with the logarithm of the intensity in much the same sigmoid way as in man, the bee, and the fiddler crab. The resolving power is very poor at low illuminations and increases at high illuminations. The maximum visual acuity is 0.0018, which is 1/1000 of the maximum of the human eye and 1/10 that of the bee. The intensity discrimination of Drosophila is also extremely poor, even at its best. At low illuminations for two intensities to be recognized as different, the higher must be nearly 100 times the lower. This ratio decreases as the intensity increases, and reaches a minimum of 2.5 which is maintained at the highest intensities. The minimum value of ΔI/I for Drosophila is 1.5, which is to be compared with 0.25 for the bee and 0.006 for man. An explanation of the variation of visual acuity with illumination is given in terms of the variation in number of elements functional in the retinal mosaic at different intensities, this being dependent on the general statistical distribution of thresholds in the ommatidial population. Visual acuity is thus determined by the integral form of this distribution and corresponds to the total number of elements functional. The idea that intensity discrimination is determined by the differential form of this distribution—that is, that it depends on the rate of entrance of functional elements with intensity—is shown to be untenable in the light of the correspondence of the two visual functions. It is suggested that, like visual acuity, intensity discrimination may also have to be considered as a function of the total number of elements active at a given intensity.     

Postoperative Metamorphopsia in Macula-Off Rhegmatogenous Retinal Detachment: Associations with Visual Function,Vision Related Quality of Life,and Optical Coherence Tomography Findings

Purpose

To evaluate postoperative metamorphopsia in macula-off rhegmatogenous retinal detachment (RRD) and its association with visual function, vision related quality of life, and optical coherence tomography (OCT) findings.

Methods

45 patients with primary macula-off RRD were included. At 12 months postoperatively, data on metamorphopsia using sine amsler charts (SAC), best corrected visual acuity (BCVA), letter contrast sensitivity, color vision (saturated and desaturated color confusion indexes), critical print size, reading acuity, the 25-item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25), and OCT, were obtained.

Results

Metamorphopsia was present in 39 patients (88.6%), with most of them (n = 35, 77.8%) showing only mild metamorphopsia (SAC score = 1). Patients with metamorphopsia had significantly worse postoperative BCVA (p = 0.02), critical print size (p<0.0005), and reading acuity (p = 0.001) compared to patients without metamorphopsia. Other visual function outcomes and NEI-VFQ-25 overall composite score were all also somewhat lower in patients with metamorphopsia, but this did not reach statistical significance. No association with OCT findings was present.

Conclusion

The prevalence of postoperative metamorphopsia in macula-off RRD patients is high, however, the degree of metamorphopsia is relatively low. When metamorphopsia is present, visual functions seem to be compromised, while vision related quality of life is only mildly affected.     

Methylnitrosourea (MNU)-induced Retinal Degeneration and Regeneration in the Zebrafish: Histological and Functional Characteristics

Retinal degenerative diseases, e.g. retinitis pigmentosa, with resulting photoreceptor damage account for the majority of vision loss in the industrial world. Animal models are of pivotal importance to study such diseases. In this regard the photoreceptor-specific toxin N-methyl-N-nitrosourea (MNU) has been widely used in rodents to pharmacologically induce retinal degeneration. Previously, we have established a MNU-induced retinal degeneration model in the zebrafish, another popular model system in visual research.A fascinating difference to mammals is the persistent neurogenesis in the adult zebrafish retina and its regeneration after damage. To quantify this observation we have employed visual acuity measurements in the adult zebrafish. Thereby, the optokinetic reflex was used to follow functional changes in non-anesthetized fish. This was supplemented with histology as well as immunohistochemical staining for apoptosis (TUNEL) and proliferation (PCNA) to correlate the developing morphological changes.In summary, apoptosis of photoreceptors occurs three days after MNU treatment, which is followed by a marked reduction of cells in the outer nuclear layer (ONL). Thereafter, proliferation of cells in the inner nuclear layer (INL) and ONL is observed. Herein, we reveal that not only a complete histological but also a functional regeneration occurs over a time course of 30 days. Now we illustrate the methods to quantify and follow up zebrafish retinal de- and regeneration using MNU in a video-format.     

Use of light intensifiers in improving acuity in retinitis pigmentosa

An English Electric Valve Co. P8073 light intensifier was set up with a viewing system to assess the performance of retinitis pigmentosa sufferers at low luminance levels. Six subjects had their acuity measured at different luminance levels using a light intensifier initially and subsequently using direct vision. All subjects showed an improvement in acuity using the intensifier compared with direct vision at levels of illumination ranging from 0.25 cd m-2 to 20 cd m-2.