Forward Light Scattering of the Vitreous Gel After Enzymatic Aging: An In Vitro Model to Study Vitreous Opacification

Purpose

Symptomatic vitreous opacifications, so-called floaters, are difficult to objectively assess majorly limiting the possibility of in vitro studies. Forward light scattering was found previously to be increased in eyes with symptomatic floaters. Using an objective setup to measure forward light scattering, we studied the effects of enzymatically digesting the components of the vitreous body on straylight to develop an in vitro model of vitreous opacifications.

Methods

Fifty-seven porcine vitreous bodies were digested using hyaluronidase, collagenase, trypsin, and bromelain, as well as using a combination of hyaluronidase + collagenase and hyaluronidase + bromelain. A modified C-Quant setup was used to objectively assess forward light scattering.

Results

Depletion of hyaluronic acid majorly increased vitreous straylight (mean increase 34.4 deg2/sr; P = 0.01), whereas primarily digesting the vitreous gel with collagenase or trypsin did not significantly affect straylight. When collagenase or bromelain is applied in hyaluronic acid depleted vitreous gels, the increase in forward light scattering is reversed partially.

Conclusions

The age-related loss of hyaluronic acid primarily drives the increase in vitreous gel straylight induced by conglomerates of collagen. This process can be reversed partially by digesting collagen. This in vitro model allows the objective quantification and statistical comparison of straylight burden caused by vitreous opacities and, thus, can serve as a first testing ground for pharmacological therapies, as demonstrated with bromelain.

Male starling floaters preferentially visit nests of males with reduced resource holding potential

Floaters are sexually mature individuals that are not able to reproduce by defending breeding resources. Floaters often visit active nests, probably to gather public information or to compete for a nesting site. We tested the hypothesis that floaters preferentially prospect nests in which they have a better chance of taking over, and that they do so by assessing the owners' resource holding potential (RHP). We manipulated the flight capacity of male and female breeders in a population of spotless starlings (Sturnus unicolor) by clipping two flight feathers per wing before egg laying, thus increasing their wing-load and likely impairing their condition. We subsequently monitored breeder and floater activity by means of transponder readers during the nestling period. We found that nests owned by wing-clipped males were visited by a greater number of male floaters than control nests. This effect was absent in the case of wing-clipped females. The number of male floaters also increased with increasing nestling age and number of parental visits. The experiment shows that male floaters preferentially prospect nests in which the owner shows a reduced RHP, a strategy that likely allows them to evict weak owners and take over their nests for future reproductive attempts.

Understanding visual snow syndrome: A retrospective study from a tertiary eye care center

PURPOSE

Visual snow syndrome is a debilitating neurological condition. A comprehensive eye examination may not detect any abnormalities in this condition. Presently the condition is recognized only through the history elicited. Hence, it becomes important to understand the presenting complaints and profile of these patients. A retrospective study at a tertiary eye care center was undertaken to achieve this goal.

METHODS

Electronic medical records of patients presenting to a Binocular Vision and Orthoptics clinic were reviewed. Records of the patients containing keywords such as "light sensitivity, shadowing, visual snow, multiple images, and night vision" were retrieved and inspected. Those matching the diagnostic criteria of visual snow syndrome were included in the study.

RESULTS

A total of 33 patients (average age ± standard deviation: 29.7 ± 9.8 years) were identified. Majority of the patients were males (69%). All the patients had logMAR visual acuity 0 or better in each eye. The most prominent (84.4%) presenting symptom was palinopsia (or afterimage or trailing). About 34.4% complained of floaters (including snow-like appearance). More than half (54.6%) of the patients also had binocular dysfunction.

CONCLUSION

Visual snow syndrome is a relatively new condition on the rise, with unclear pathology. The symptoms of this condition can easily be confused with regular floaters or black spots seen in vitreous and retinal pathologies. In the absence of such pathology, an elaborate history should be elicited, and the distress of the patient should be acknowledged. The patient should also be reassured that this is not a blinding condition.

Patients with floaters: Answers from virtual assistants and large language models

Objectives

"Floaters," a common complaint among patients of all ages, was used as a query term because it affects 30% of all people searching for eye care. The American Academy of Ophthalmology website's "floaters" section was used as a source for questions and answers (www.aao.org). Floaters is a visual obstruction that moves with the movement of the eye. They can be associated with retinal detachment, which can lead to vision loss. With the advent of large language model (LLM) chatbots ChatGPT, Bard versus virtual assistants (VA), Google Assistant, and Alexa, we analyzed their responses to "floaters."

Methods

Using AAO.org, "Public & Patients," and its related subsection, "EyeHealth A-Z": Floaters and Flashes link, we asked four questions: (1) What are floaters? (2) What are flashes? (3) Flashes and Migraines? (4) Floaters and Flashes Treatment? to ChatGPT, Bard, Google Assistant, and Alexa. The American Academy of Ophthalmology (AAO) keywords were identified if they were highlighted. The "Flesch-Kincaid Grade Level" formula approved by the U.S. Department of Education, was used to evaluate the reading comprehension level for the responses.

Results

Of the chatbots and virtual assistants, Google Assistant is the only one that uses the term "ophthalmologist." There is no mention of the urgency or emergency nature of floaters. AAO.org shows a lower reading level vs the LLMs and VA (p = .11). The reading comprehension levels of ChatGPT, Bard, Google Assistant, and Alexa are higher (12.3, 9.7, 13.1, 8.1 grade) vs the AAO.org (7.3 grade). There is a higher word count for LLMs vs VA (p < .0286).

Conclusion

Currently, ChatGPT, Bard, Google Assistant, and Alexa are similar. Factual information is present but all miss the urgency of the diagnosis of a retinal detachment. Translational relevance: Both the LLM and virtual assistants are free and our patients will use them to obtain "floaters" information. There may be errors of omission with ChatGPT and a lack of urgency to seek a physician's care.

Long-term efficacy and safety of YAG laser vitreolysis for vision degrading myodesopsia

AIM

To assess the long-term efficacy and safety of yttrium-aluminum garnet (YAG) laser vitreolysis for vision degrading myodesopsia (VDM) caused by posterior vitreous detachment (PVD).

METHODS

This retrospective study reviewed VDM patients of PVD type undergoing YAG laser vitreolysis. The baseline demographic information, the patterns of floaters, the number of floaters, and the subjective improvement of floater sympotoms (ranging from 0 to 100%) from medical records were collected. Significant improvement was defined as a relief of floater symptoms of ≥50% at the final visit. The long-term efficacy and safety of YAG laser vitreolysis were analyzed. The risk factors linked to significant improvement of floater symptoms were defined using univariate and multivariate logistic regression analyses.

RESULTS

The final analysis included 221 patients with VDM. The mean age of patients was 61.08±7.74y, and the mean length of follow-up was 21.38±5.61mo. Totally 57.01% of patients experienced a significant improvement in their floater symptoms after YAG laser therapy, and none of them developed delayed retinal abnormalities such as retinal tears or detachments. Age (OR=1.049, 95%CI=1.007-1.092, P=0.021) was identified as a significant risk factor for significant improvement in VDM.

CONCLUSION

YAG laser vitreolysis is an effective and secure treatment for PVD-type VDM, and patients of advanced age are more likely to get favorable outcomes.

Machine Independence of Ultrasound-Based Quantification of Vitreous Echodensities

Purpose

Quantitative ultrasound (QUS) provides objective indices of Vision Degrading Myodesopsia (VDM) that correlate with contrast sensitivity (CS). To date, QUS methods were only tested on a single ultrasound machine. Here, we evaluate whether QUS measurements are machine independent.

Methods

In this cross-sectional study, 47 eyes (24 subjects; age = 53.2 ± 14.4 years) were evaluated with Freiburg acuity contrast testing (%Weber), and ultrasonography using 2 machines: one with a 15-MHz single-element transducer and one with a 5-ring, 20-MHz annular-array. Images were acquired from each system in sequential scans. Artifact-free, log-compressed envelope data were processed to yield three parameters (mean amplitude, M; energy, E; and percentage filled by echodensities, P50) and a composite score (C). A B-mode normalization method was applied to the 20-MHz datasets to match QUS parameters at both frequencies. Statistical analyses were performed to evaluate correlations among CS, E, M, P50, and C for both machines.

Results

QUS parameters from each machine correlated with CS (R ≥ 0.57, P < 0.001) and there was correlation between machines (R ≥ 0.84, P < 0.001). Correlations between CS and QUS parameters were statistically similar for both machines (P ≥ 0.14) except when the 20-MHz data were normalized (P = 0.04). Reproducibility of QUS parameters computed from 20-MHz data were satisfactory (52.3%-96.3%) with intraclass correlation values exceeding 0.80 (P < 0.001).

Conclusions

The high correlation between QUS parameters from both machines combined with a statistically similar correlation to CS suggests QUS is an effective, machine-independent, quantitative measure of vitreous echodensities.

Translational Relevance

QUS may be applied across clinical ophthalmic ultrasound scanners and imaging frequencies to effectively evaluate VDM.

Dynamic Infrared Imaging of Vitreous Floaters

Background and Objective

To evaluate the use of dynamic infrared (IR) imaging as a tool for the objective evaluation of symptomatic vitreous floaters and to correlate it with the patient symptomatology.

Study Design/Materials and Methods

Retrospective study that examined 66 eyes of 44 patients with symptomatic and asymptomatic vitreous opacities. Patients were imaged using the Heidelberg Spectralis dynamic infrared (IR) image in video mode to record the vitreous movements and shadow artifacts within 30 degrees of the center of the macula. Patients were also asked how symptomatic their vitreous floaters were from absent to severe. After reviewing IR videos and OCT, a grading system was created to evaluate the floaters and a masked reader was asked to evaluate the videos and OCT based on the grading system created.

Results

A total of 66 eyes were identified and examined with the IR videos, 50 were symptomatic, and 16 were asymptomatic. After masked review and analysis of the IR videos, there were 4 characteristics that correlated with the patient's symptoms: size, location, movement, and density of obscuration of the OCT B Scan by the vitreous opacity. A table with grading of these characteristics was created to analyze how symptomatic patients were. A masked grader was asked to grade the videos and OCT using the grading system created. A positive correlation was found between the masked grader and the symptoms of patients. (0.70039; p < 0.00001).

Conclusion

Dynamic IR video capture of vitreous opacities is a new imaging technique that can qualitatively assess vitreous opacities in a way that correlates to a patient's symptoms. This imaging modality can provide a qualitative assessment of the patient's severity of symptoms based on the location, density, and movement of the visualized vitreous opacities in the imaged video.

Hide-and-Seek in a Highly Human-Dominated Landscape: Insights into Movement Patterns and Selection of Resting Sites of Rehabilitated Wolves (Canis lupus) in Northern Italy

Assessing the behavioural responses of floating wolves to human presence is crucial for investigating the chance of wolf populations expanding into urbanised landscapes. We studied the movement ecology of three rehabilitated wolves in a highly human-dominated landscape (Po Plain, Italy) to explore wolf's plasticity amid widespread human pressure. To reach this aim, we estimated individual 95% utilisation distributions (UD) after the release and inspected both 95% UDs and net squared displacements to identify individual movement patterns; tested for differences in movement patterns during day and night; and analysed the selection of resting sites during dispersal movement in a highly human-altered environment. Both the 95% UDs and step lengths were smaller for wolves settling in suitable areas than for those settling in more urbanised areas. All wolves exhibited strong temporal segregation with humans during all movement phases, particularly while dispersing across highly urbanised areas. Main roads and proximity to built-up areas were shown to limit wolves' dispersal, whereas small-wooded patches that provide shelter during rest facilitated long-distance movements. This study provides important insights into wolf movement and settling in urban and peri-urban areas, providing critical knowledge to promote human-carnivore coexistence.

The effectiveness of laser vitreolysis for vitreous floaters in posterior vitreous detachment

Purpose

To determine the effectiveness of laser vitreolysis in terms of contrast sensitivity function (CSF) and vision-related quality of life (VRQol) for symptomatic floaters due to posterior vitreous detachment (PVD).

Materials

This is an interventional study that involved 57 eyes of 45 patients with symptomatic floaters for more than 3 months. Patients underwent one to three sessions of vitreolysis via Neodymiun-doped Yttrium Aluminum Garnet (Nd:YAG) laser. We examined the CSF using the computer programs Freiburg Acuity and Contrast Test (FrACT) and VRQoL survey using the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25) before, and 1 month after, vitreolysis.

Results

Twelve patients had both eyes lasered and 33 patients had one eye lasered. The mean CSF improved from 3.20 ± 0.85%W to 2.64 ± 0.63%W 1 month after vitreolysis. Each use of the laser showed a significant mean difference in CSF (%W) as analyzed by paired t-test before and after the first laser (0.29 ± 0.49%W [P ≤ 0.001]); after the first and second laser (0.35 ± 0.53%W [P = 0.01]); and after second and third laser (0.21 ± 0.31%W [P = 0.02]). There was improvement in the median of four subscales in NEI VFQ-25 scores post treatment: general vision (z = -3.30, P = 0.001), near activity (z = 3.396, P = 0.001, distance activity (z = -2.788, P = 0.005), and mental health (z = -2.219, P = 0.026). The mean scores increased to 79.55 ± 9.45 from the baseline 75.06 ± 9.69 (P ≤ 0.001). No adverse events were recorded 1 month after the laser treatments.

Conclusion

Vitreolysis by Nd:YAG laser improved the CFS and VRQoL in symptomatic PVD patients.

Optical Scattering from Vitreous Floaters

Vitreous “floaters” are a common entoptic phenomenon that can result in significant reduction in quality of life in a proportion of sufferers. The authors use a computational mathematical model based on Fourier optics and reflection and transmission coefficients calculated for a planar type II collagen opacity suspended in aqueous to show that floaters are perceived by the patient through interference effects that result in significant variations in intensity on the retina when viewing a constant brightness surface. The model also predicts that backscattered intensity from floaters is ten thousand to one million times lower than the variations in intensity produced on the retina, which demonstrates that the visible effects of floaters for the patient can be highly significant, whereas clinical observation of the vitreous may be entirely unremarkable. Importantly, the results also demonstrate that floaters do not need to be opaque to cause symptoms, with only small differences in refractive index between the floater material and the surrounding vitreous needed to produce significant optical effects. The model predicts that pupil size is an important factor in determining the severity of symptoms from floaters, with constricted pupils giving much greater effect than dilated pupils. Finally, the authors’ model predicts that floaters degrade contrast sensitivity function, with greatest degradation occurring in the 5–40 cycles per degree spatial frequency range and that the effects of shadowing caused by floaters are very strongly correlated to the predicted degradation of contrast sensitivity function. Bioelectromagnetics. 43:90–105, 2022. © 2021 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.

Impact of symptomatic vitreous degeneration on photopic and mesopic contrast thresholds

CLINICAL RELEVANCE

Contrast thresholds under photopic and mesopic luminance conditions are compromised in subjects with vitreous degeneration. A plausible explanation is needed for the visual discomfort expressed by patients suffering from symptomatic vitreous degeneration.

BACKGROUND

The current study investigates the effect of symptomatic vitreous degeneration on photopic and mesopic contrast at high spatial frequencies.

METHODS

An age-matched sample of 115 subjects, comprising 30 subjects with symptomatic vitreous floaters (cases) and 85 healthy subjects (controls), was included in this study. Visual acuity and flicker thresholds were measured for all participants. Photopic and mesopic functional contrast thresholds at 10 cycles per degree were measured for all participants to assess the effect of floaters on contrast. Further, to determine the effect of posterior vitreous detachment on contrast, the sample was divided into three groups: cases with posterior vitreous detachment (n = 12); cases without posterior vitreous detachment (n = 18); and controls (n = 85), and their contrast thresholds were compared.

RESULTS

Photopic and mesopic contrast thresholds were lower by 37.4% and 27.5%, respectively, when the cases were compared with the controls (p = 0.028 and p < 0.001 for photopic and mesopic contrast thresholds, respectively). Photopic contrast was lower by 64.0% in cases with posterior vitreous detachment compared with controls (p = 0.001). Compared with controls, mesopic contrast was lower in cases with posterior vitreous detachment and in cases without posterior vitreous detachment by 30.3% and 25.6%, respectively (p = 0.014 and p = 0.017 for cases with and without posterior vitreous detachment, respectively).

CONCLUSION

: Subjects with vitreous degeneration have diminished photopic and mesopic contrast thresholds compared with controls. This finding highlights the negative impact of vitreous degeneration on the quality of vision.

Female and male Eurasian lynx have distinct spatial tactics at different life-history stages in a high-density population

Knowledge regarding the spatial behavior of the Eurasian lynx is mainly inferred from populations in Europe. We used GPS telemetry to record the spatial behavior of nine individuals in northwestern Anatolia obtaining eleven home ranges (HRs). Analyses revealed the smallest mean HR sizes (nHR ♀  = 4) at 57 km2 (95% kernel utilization distribution, KUD) and 56 km2 (95% minimum convex polygon, MCP), ever reported for adult female Eurasian lynx. Adult males either occupied small permanent territories (nHR♂.T = 2), with a mean of 176 km2 (95% KUD) and 150 km2 (95% MCP), or were residents without territories (floaters, nHR♂. F  = 2) roaming across large, stable HRs with a mean size of 2,419 km2 (95% KUD) and 1,888 km2 (95% MCP), comparable to HR sizes of Scandinavian lynx populations. Three disperser subadult males did not hold stable HRs (mean 95% KUD = 203 km2, mean 95% MCP = 272 km2). At 4.9 individuals per 100 km2, population density was one of the highest recorded, suggesting that the presence of adult male floaters was a consequence of a landscape fully occupied by territorials and revealing a flexibility of spatial behavior of Eurasian lynx not previously recognized. Such a high population density, small HRs, and behavioral flexibility may have been aided by the legal protection from and apparent low levels of poaching of this population. The observed spatial tactics are unlikely to be seen in most of the previously studied Eurasian lynx populations, as they either suffer medium to high levels of human-caused mortality or were unlikely to be at carrying capacity. For effective and appropriate conservation planning, data from felid populations in a reasonably natural state such as ours, where space, density, prey, and pathogens are likely to be the key drivers of spatial dynamics, are therefore essential.

Nd:YAG laser vitreolysis and health-related quality of life in patients with symptomatic vitreous floaters

BACKGROUND

The treatment of floaters has consisted primarily of monitoring. The therapeutic approach is based on surgical removal or Nd:YAG laser treatment. The objective of this study was the assessment of the quality of life in patients treated with Nd:YAG laser for floaters.

METHODS

Single-center pretest-posttest design in a cohort of subjects treated with Nd-YAG laser with Ultra Q-Reflex technology. Health-related quality of life of the patients was measured before and after the intervention with the Visual Function Questionnaires VFQ-25 and VFQ-39. Anxiety level was measured with the State-Trait Anxiety Inventory. Visual acuity, contrast sensitivity, and safety parameters were also considered.

RESULTS

Thirty-four patients were included in the study. For the VFQ-25 baseline, the median was 73.05, interquartile range (19.25) versus a final median value of 93.76 (8.73) with p < 0.01. The baseline median for the extended version VFQ-39 was 74.60 (19.01) versus the final median of 95.01 (6.50) with p < 0.001. Regarding the anxiety, according to the STAI questionnaire, there were statistically significant differences between the baseline and the final conditions, with a baseline median of 38 (11) versus a final median of 18 (19); p < 0.001. When the analyses differentiated between patients with and without myopia, there were statistically significant differences for VFQ-25 and VFQ-39.

CONCLUSIONS

This study shows an improvement in the health-related quality of life and a significant decrease in anxiety for patients that have undergone Nd: YAG Ultra-Q Reflex laser vitreolysis for floaters vaporization. The effect found is higher in myopic patients.

Demographic modeling to fine-tune conservation targets: importance of pre-adults for the decline of an endangered raptor

Large, long-lived species with slow life histories and protracted pre-breeding stages are particularly susceptible to declines and extinction, often for unknown causes. Here, we show how demographic modeling of a medium-sized raptor, the Red Kite Milvus milvus, can aid to refocus conservation research and attention on the most likely mechanisms driving its decline. Red Kites' survival and reproduction increased through three sequential stages for 1-2, 3-6, and 7-30 yr of age, mainly corresponding to individuals that are dispersing, attempting to gain a territory, and breeding. As typical of long-lived species, elasticities were highest for adult (≥7 yr old) survival, but this was high, with little scope for improvement. Instead, the declines were driven by an extremely low survival of pre-adults in their first years of life, which weakened the whole demographic system by nullifying the offspring contribution of adults and curtailing their replacement by recruits. For example, 27 pairs were necessary to generate a single prime age adult. Simulation of management scenarios suggested that the decline could be halted most parsimoniously by increasing pre-adult survival to the mean levels recorded for other areas, while only the synergistic, simultaneous improvement of breeding success, adult and pre-adult survival could generate a recovery. We propose three actions to attain such goals through selective supplementary feeding of both breeding and non-breeding individuals, and through mortality improvement by GPS remote-sensing devices employed as surveillance monitoring tools. Our results show how improving demographic models by using real, local vital rates rather than "best guess" vital rates can dramatically improve model realism by refocusing attention on the actual stages and mortality causes in need of manipulation, thus building precious time and resources for conservation management. These results also highlight the frequent key role of pre-adult survival for the management of long-lived species, coherent with the idea of demographic systems as integrated chains only as strong as their weakest link.

Evaluation of Available Online Information Regarding Treatment for Vitreous Floaters

OBJECTIVE

To assess the quality, content, and readability of information available online on vitreous floater information.

DESIGN

Cross-sectional study.

PARTICIPANTS

Not applicable.

METHODS

Websites were generated using a Google search of "vitreous floaters treatment" and "[State]" and were analyzed using a standardized checklist of 22 questions. Readability was assessed using the Flesch Reading Ease score. Websites met qualification criteria if they represented U.S.-based institutions, if they provided clinical care and addressed vitreous floater treatment on their website.

RESULTS

Of the 1,065 websites screened, 456 were included. Of these, 406 (89%) were private institutions, 24 (5.3%) were academic, and 26 (5.7%) were a combination of private and academic. The average readability score correlated to a 10th-12th grade reading level. Vitreous floater treatment was discussed on 283 (62.1%) websites and 63 (21.8%) websites discussed potential side effects. Google rank was inversely correlated with the depth of explanation (r = -0.114, p = .016). Observation was the main treatment recommended (55.8%, n = 158), followed by laser treatment (27.6%, n = 78), no specific treatment recommendation (11.3%, n = 32), and vitrectomy (5.3%, n = 15). Centers with vitreoretinal surgeons were 16.43 times more likely to recommend vitrectomy than those without vitreoretinal surgeons (p < .001).

CONCLUSIONS

Online information about vitreous floater treatment is variable, and the material is at a higher than recommended reading level for health information. While treatment was discussed by nearly two thirds of websites, less than a quarter mentioned possible complications, and treatment recommendations varied significantly depending on physician training.

Asymmetric competition and floater dynamics

In territorial species, nonterritorial floaters may be critical to population dynamics. One theoretical framework, based on the assumption that floating is a strategic decision to forego reproduction, predicts that selection maintains an abundant floater population even if low-quality territories are available. However, existing models make two critical assumptions: all individuals have equal competitive ability, and every individual in a population has access to every available territory. We assess the consequences of relaxing these assumptions in a model of asymmetric competition with a trade-off between investment in competitiveness and reproductive success. Our results demonstrate that selection for greater competitiveness eliminates floater production unless the outcome of territorial contests has a strong stochastic component. Next, we suppose individuals can compete for territories only within a fixed neighborhood. If this constraint is sufficiently strong, our model predicts that a population will produce floaters. Finally, we show that our model makes novel predictions regarding the maintenance of trait variation and the relationship between this variation and the distribution of competitors among unequal territories.

The dynamic trophic niche of an island bird of prey

Optimal foraging theory predicts an inverse relationship between the availability of preferred prey and niche width in animals. Moreover, when individuals within a population have identical prey preferences and preferred prey is scarce, a nested pattern of trophic niche is expected if opportunistic and selective individuals can be identified. Here, we examined intraspecific variation in the trophic niche of a resident population of striated caracara (Phalcoboenus australis) on Isla de los Estados (Staten Island), Argentina, using pellet and stable isotope analyses. While this raptor specializes on seabird prey, we assessed this population's potential to forage on terrestrial prey, especially invasive herbivores as carrion, when seabirds are less accessible. We found that the isotopic niche of this species varies with season, age, breeding status, and, to a lesser extent, year. Our results were in general consistent with classic predictions of the optimal foraging theory, but we also explore other possible explanations for the observed pattern. Isotopic niche was broader for groups identified a priori as opportunistic (i.e., nonbreeding adults during the breeding season and the whole population during the nonbreeding season) than it was for individuals identified a priori as selective. Results suggested that terrestrial input was relatively low, and invasive mammals accounted for no more than 5% of the input. The seasonal pulse of rockhopper penguins likely interacts with caracara's reproductive status by constraining the spatial scale on which individuals forage. Niche expansion in spatially flexible individuals did not reflect an increase in terrestrial prey input; rather, it may be driven by a greater variation in the types of marine prey items consumed.

Laser vitreolysis for symptomatic floaters is not yet ready for widespread adoption

Vitreous floaters are common, related to age, myopia, genetic predisposition, and infiltration of the vitreous body. A subset of patients report symptoms impacting their quality of vision. Treatment with laser vitreolysis, the use of an Nd:YAG laser to vaporize the collagenous vitreous opacities appears to be used more frequently; however, data regarding long-term safety and effectiveness are lacking. We present currently available data regarding efficacy and safety, as well as additional considerations. Laser vitreolysis of symptomatic floaters should not be routinely performed without additional studies documenting its safety and long-term efficacy. Ideally, the procedure would be effective in most patients and be approved by the Food and Drug Administration based on the results of a Food and Drug Administration registration trial before widespread adoption.

Vitreous Antioxidants, Degeneration, and Vitreo-Retinopathy: Exploring the Links

The transparent vitreous body, which occupies about 80% of the eye’s volume, is laden with numerous enzymatic and non-enzymatic antioxidants that could protect the eye from oxidative stress and disease. Aging is associated with degeneration of vitreous structure as well as a reduction in its antioxidant capacity. A growing body of evidence suggests these age-related changes may be the precursor of numerous oxidative stress-induced vitreo-retinopathies, including vision degrading myodesopsia, the clinically significant entoptic phenomena that can result from advanced vitreous degeneration. Adequate intravitreal antioxidant levels may be protective against vitreous degeneration, possibly preventing and even improving vision degrading myodesopsia as well as mitigating various other vitreo-retinopathies. The present article is, therefore, a review of the different antioxidant molecules within vitreous and the inter-relationships between vitreous antioxidant capacity and degeneration.

Rare cause of floaters: A motile live worm in vitreous cavity

Ocular filariasis commonly presents as subconjunctival or eyelid nodules. We report a rare case of a live, motile worm causing floaters. The worm was isolated from the vitreous cavity and revealed to be Dirofilaria repens. Correct recognition of the worm is necessary as human dirofilariasis does not present as microfilaremia and does not require systemic therapy; in contrast to other causes of ocular filariasis, which require systemic therapy. As ophthalmologist may be the first physician to encounter such patients, a high index of suspicion is required for timely and adequate management.

Symptoms related to posterior vitreous detachment and the risk of developing retinal tears: a systematic review

Flashes and floaters are the hallmark symptoms of a posterior vitreous detachment (PVD) which itself is related to an increased risk of the development of retinal tears, retinal detachment and vitreous haemorrhage. The aim of this study is to assess the associations between different symptoms related to PVD and the risk of developing retinal tears. A systematic review of articles written in English, using MEDLINE, Embase (via Embase.com) and the Cochrane Controlled Trials Register (1996-2017) was conducted. Search terms included five elements: PVD, retinal tears, retinal detachment, floaters and flashes. Independent extraction of articles was conducted by two authors using predefined data fields, including study quality indicators. Thirteen studies fulfilled the selection criteria. Analysis of pooled data revealed that presence of isolated flashes was associated with the development of retinal tears in 5.3% of symptomatic eyes [mean 2.9 eyes; 95% CI (2.1, 5.7)].Conversely, floaters alone had a stronger association with retinal tears (16.5% of eyes), as compared to flashes. The association to retinal tears was even greater for those patients reporting both flashes and floaters [mean 17.8 eyes (20.0%); 95% CI (17.4, 18.1)]. Retinal and/or vitreous haemorrhage was also associated with the presence and later development of retinal tears [mean 12.5 eyes (30.0%); 95% CI (11.7, 13.9)]. Patients with more than 10 floaters or a cloud in their vision had a high risk of developing retinal tears (OR19.8, p-value 0.032). In the setting of a PVD, the onset of flashes and floaters, and the presence of retinal and/or vitreous haemorrhage are risk factors for the development of retinal tears. The association is greater when both symptoms are present, and even greater when the patient reports more than 10 floaters, a curtain or a cloud and/or there is a positive finding of a vitreous or retinal haemorrhage. This study supports the necessity of an immediate examination of patients presenting with symptoms related to a PVD, and a follow-up examination might be prudent in a subgroup of these patients.

Rheological Properties and Age-Related Changes of the Human Vitreous Humor

The vitreous humor is a fragile, transparent hydrogel situated between the lens and the retina, occupying 80% of the eye's volume. Due to its viscoelastic behavior, the vitreous serves as a mechanical damper for the eye, absorbing impacts, and protecting the lens and retina. The vitreous liquefies with age, which compromises its function as a shock absorber and causes complications including retinal detachment, macular holes, and vitreous hemorrhage. Studies on the viscoelastic properties of the vitreous have been limited. Rheological testing of the vitreous has commonly been done on non-primate mammalian species. Human vitreous rheological properties have been previously reported; however, various measurement techniques were used, resulting in data that differed by orders of magnitude. Shear rheometry is commonly used to characterize soft tissues and hydrogels such as the vitreous humor. However, no human vitreous rheological data have been reported using this technique, preventing direct comparison to other published work. Additionally, no age-related changes in the mechanical properties of the human vitreous humor have been reported. Human vitreous samples (n = 39, aged 62 ± 15 years) were tested using a shear rheometer. Small amplitude oscillatory shear and creep experiments were performed. The linear viscoelastic region of the human vitreous was found to be below 1% strain. The solid phase of the old human vitreous was found to be stiffer than the young human vitreous and the porcine vitreous. The stiffness of the human vitreous gel also appeared to be positively correlated with age. Vitreous dehydration due to a decrease in hyaluronic acid concentration with age was proposed to cause the stiffening of the solid phase of the vitreous gel. Vitreous liquefaction, therefore, might be characterized as a simultaneous increase in liquid volume and localized stiffening of the vitreous gel. The phase separation of the vitreous humor with age has been hypothesized as the cause of many vitreous-related complications. This study provides viscoelastic properties and age-related changes of the human vitreous humor, which will aid in the design of biomimetic vitreous substitutes, enhancement in analyzing intravitreal transport of therapeutics, and understanding the pathological conditions of the vitreous humor.

Two-Port Pars Plana Anterior and Central Core Vitrectomy (Lam Floaterectomy) in Combination With Phacoemulsification and Intraocular Lens Implantation Under Topical Anesthesia for Patients with Cataract and Significant Floaters: Results of the First 50 Consecutive Cases

PURPOSE

To study the safety and efficacy of 2-port pars plana anterior and central core vitrectomy (Lam floaterectomy) in combination with phacoemulsification (phaco) and intraocular lens implantation (IOL) for patients with cataract and significant floaters under topical anesthesia.

DESIGN

Retrospective review of the first 50 consecutive cases.

METHODS

A standardized treatment protocol was used for patients with cataract and significant (moderate to severe) floaters (duration > 3 months). Data analysis included intraoperative and postoperative complications, floater status, and patient satisfaction.

RESULTS

There were 50 eyes (38 patients) with a male-to-female ratio of 1 to 2.3. Twelve patients had bilateral eye surgeries. Mean age was 58.10 ± 9.85 years (range, 39-83). All patients completed the 3-month follow-up. One eye had mild vitreous hemorrhage at the end of surgery arising from sclerotomy wound oozing. No other intraoperative compli-cations were encountered. Postoperatively, there was 1 case of transient hypotony and 1 case of congestion at sclerotomy wound. No cases of retinal break or detachment, or clinically significant macular edema, were reported. There were 5 cases (10%) of mild residual floaters and 1 case (2%) of floater recurrence. Total floater clearance rate was 88%. Patient satisfaction rates were 80%, 14%, 6%, and 0% for very satisfied, satis-fied, acceptable, and unsatisfied, respectively.

CONCLUSIONS

The 3-month results in terms of safety and efficacy of the Lam floaterectomy in combination with phaco and IOLfor patients with cataract and significant floaters under topical anesthesia are encouraging. Further larger-scale, prospective, multicenter studies seem warranted.

Modelling effects of nonbreeders on population growth estimates

Adult individuals that do not breed in a given year occur in a wide range of natural populations. However, such nonbreeders are often ignored in theoretical and empirical population studies, limiting our knowledge of how nonbreeders affect realized and estimated population dynamics and potentially impeding projection of deterministic and stochastic population growth rates. We present and analyse a general modelling framework for systems where breeders and nonbreeders differ in key demographic rates, incorporating different forms of nonbreeding, different life histories and frequency-dependent effects of nonbreeders on demographic rates of breeders. Comparisons of estimates of deterministic population growth rate, λ, and demographic variance, σd2, from models with and without distinct nonbreeder classes show that models that do not explicitly incorporate nonbreeders give upwardly biased estimates of σd2, particularly when the equilibrium ratio of nonbreeders to breeders, Nnb∗/Nb∗, is high. Estimates of λ from empirical observations of breeders only are substantially inflated when individuals frequently re-enter the breeding population after periods of nonbreeding. Sensitivity analyses of diverse parameterizations of our model framework, with and without negative frequency-dependent effects of nonbreeders on breeder demographic rates, show how changes in demographic rates of breeders vs. nonbreeders differentially affect λ. In particular, λ is most sensitive to nonbreeder parameters in long-lived species, when Nnb∗/Nb∗>0, and when individuals are unlikely to breed at several consecutive time steps. Our results demonstrate that failing to account for nonbreeders in population studies can obscure low population growth rates that should cause management concern. Quantifying the size and demography of the nonbreeding section of populations and modelling appropriate demographic structuring is therefore essential to evaluate nonbreeders' influence on deterministic and stochastic population dynamics.

Vitreous floaters: Etiology, diagnostics, and management. Surv Ophthalmol. 2016;61:211-227. [PMID: 26679984 DOI: 10.1016/j.survophthal.2015.11.008]

Vitreous is a hydrated extracellular matrix comprised primarily of water, collagens, and hyaluronan organized into a homogeneously transparent gel. Gel liquefaction results from molecular alterations with dissociation of collagen from hyaluronan and aggregation of collagen fibrils forming fibers that cause light scattering and hence symptomatic floaters, especially in myopia. With aging, gel liquefaction and weakened vitreoretinal adhesion result in posterior vitreous detachment, the most common cause of primary symptomatic floaters arising from the dense collagen matrix of the posterior vitreous cortex. Recent studies indicate that symptomatic floaters are not only more prevalent, but also have a negative impact on the quality of life that is greater than previously appreciated. We review the literature concerning management of symptomatic vitreous floaters, currently either with observation, vitrectomy, or Nd:YAG laser. Published evidence is consistent with a low-risk profile and excellent success rate for floater vitrectomy, particularly with sutureless small gauge instruments and a limited core vitrectomy without PVD induction. Nd:YAG laser treatment of floaters, reported less commonly, claims resolution of floaters ranging between 0% and 100%; however, both peer-reviewed literature and assertions on web-based nonpeer-reviewed laser vitreolysis sites remain to be substantiated, and at present only vitrectomy has proven value. Prospective studies using objective, quantitative outcome measures are required to assess the relative efficacy and safety of these two procedures as well as new therapies such as pharmacologic vitreolysis.

Ultrasound-based quantification of vitreous floaters correlates with contrast sensitivity and quality of life

PURPOSE

Clinical evaluation of floaters lacks quantitative assessment of vitreous structure. This study used quantitative ultrasound (QUS) to measure vitreous opacities. Since floaters reduce contrast sensitivity (CS) and quality of life (Visual Function Questionnaire [VFQ]), it is hypothesized that QUS will correlate with CS and VFQ in patients with floaters.

METHODS

Twenty-two eyes (22 subjects; age = 57 ± 19 years) with floaters were evaluated with Freiburg acuity contrast testing (FrACT; %Weber) and VFQ. Ultrasonography used a customized probe (15-MHz center frequency, 20-mm focal length, 7-mm aperture) with longitudinal and transverse scans taken in primary gaze and a horizontal longitudinal scan through premacular vitreous in temporal gaze. Each scan set had 100 frames of log-compressed envelope data. Within each frame, two regions of interest (ROIs) were analyzed (whole-central and posterior vitreous) to yield three parameters (energy, E; mean amplitude, M; and percentage of vitreous filled by echodensities, P50) averaged over the entire 100-frame dataset. Statistical analyses evaluated E, M, and P50 correlations with CS and VFQ.

RESULTS

Contrast sensitivity ranged from 1.19%W (normal) to 5.59%W. All QUS parameters in two scan positions within the whole-central ROI correlated with CS (R > 0.67, P < 0.001). P50 in the nasal longitudinal position had R = 0.867 (P < 0.001). Correlations with VFQ ranged from R = 0.52 (P < 0.013) to R = 0.65 (P < 0.001).

CONCLUSIONS

Quantitative ultrasound provides quantitative measures of vitreous echodensity that correlate with CS and VFQ, providing objective assessment of vitreous structure underlying the functional disturbances induced by floaters, useful to quantify vitreous disease severity and the response to therapy.

Cytologic features in vitreous preparations of patients with suspicion of intraocular lymphoma

Intraocular lymphoma may occur, primarily with or without overt parenchymal CNS lymphoma or secondarily from a variety of other lymphomas. The diagnosis is frequently based on cytologic features and/or a limited panel of ancillary techniques. Twenty-seven cytology samples from the vitreous preparations of 20 patients with clinical suspicion or histopathologic diagnoses of lymphoma were retrospectively reviewed (2007-2011). Floaters and decreased visual acuity were the most common ocular symptoms. Sixteen (of 20) patients had at least one cytology that was "positive" or "suspicious" for lymphoma (F = 10; M = 6, median age = 71 years, range = 52-82). Involvement was limited to the eye in half of the cases (n = 8). Seven patients had CNS involvement, and three had systemic lymphoma. Cytologic specimens were classified as large B cell lymphoma (LBCL) (n = 13), suspicious for LBCL (n = 5), atypical/negative (n = 5), and consistent with NK-T cell lymphoma (n = 1). Three cytologic samples were acellular. Cytologic findings included increased cellularity (high n = 7, moderate n = 7), large to medium (n = 19) cell size, marked nuclear irregularities (n = 12), frequent apoptosis (n = 7), lymphoglandular bodies (n = 12), and necrosis (n = 12). Easily identifiable mitotic figures were present in two cases. CD20 immunocytochemistry performed in 15 cases with available cell blocks/destained cytospins preparations, was confirmatory in 8 cases. Cytologic evaluation of intraocular lymphoma is possible in vitreous specimens. Extraocular involvement was not present in half of the cases. The most useful cytologic features include increased cellularity, necrosis, and nuclear enlargement. Ancillary immunocytochemical studies are useful and support the morphologic impression in a subset of cases.

Demographic responses of a site-faithful and territorial predator to its fluctuating prey: long-tailed skuas and arctic lemmings

Environmental variability, through interannual variation in food availability or climatic variables, is usually detrimental to population growth. It can even select for constancy in key life-history traits, though some exceptions are known. Changes in the level of environmental variability are therefore important to predict population growth or life-history evolution. Recently, several cyclic vole and lemming populations have shown large dynamical changes that might affect the demography or life-histories of rodent predators. Skuas constitute an important case study among rodent predators, because of their strongly saturating breeding productivity (they lay only two eggs) and high degree of site fidelity, in which they differ from nomadic predators raising large broods in good rodent years. This suggests that they cannot capitalize on lemming peaks to the same extent as nomadic predators and might be more vulnerable to collapses of rodent cycles. We develop a model for the population dynamics of long-tailed skuas feeding on lemmings to assess the demographic consequences of such variable and non-stationary prey dynamics, based on data collected in NE Greenland. The model shows that populations of long-tailed skua sustain well changes in lemming dynamics, including temporary collapses (e.g. 10 years). A high floater-to-breeder ratio emerges from rigid territorial behaviour and a long-life expectancy, which buffers the impact of adult abundance's decrease on the population reproductive output. The size of the floater compartment is affected by changes in both mean and coefficient of variation of lemming densities (but not cycle amplitude and periodicity per se). In Greenland, the average lemming density is below the threshold density required for successful breeding (including during normally cyclic periods). Due to Jensen's inequality, skuas therefore benefit from lemming variability; a positive effect of environmental variation. Long-tailed skua populations are strongly adapted to fluctuating lemming populations, an instance of demographic lability in the reproduction rate. They are also little affected by poor lemming periods, if there are enough floaters, or juveniles disperse to neighbouring populations. The status of Greenland skua populations therefore strongly depends upon floater numbers and juvenile movements, which are not known. This reveals a need to intensify colour-ringing efforts on the long-tailed skua at a circumpolar scale.

Prevalence of vitreous floaters in a community sample of smartphone users

AIM

To estimate the prevalence and risk factors for vitreous floaters in the general population.

METHODS

An electronic survey was administered through a smartphone app asking various demographic and health questions, including whether users experience floaters in their field of vision. Multivariate logistic regression analysis was used to determine risk factors.

RESULTS

A total of 603 individuals completed the survey, with 76% reporting that they see floaters, and 33% reporting that floaters caused noticeable impairment in vision. Myopes were 3.5 times more likely (P=0.0004), and hyperopes 4.4 times more likely (P=0.0069) to report moderate to severe floaters compared to those with normal vision. Floater prevalence was not significantly affected by respondent age, race, gender, and eye color.

CONCLUSION

Vitreous floaters were found to be a very common phenomenon in this non-clinical general population sample, and more likely to be impairing in myopes and hyperopes.

Environmental stochasticity in dispersal areas can explain the "mysterious" disappearance of breeding populations

We present the results of an individual-based simulation model, showing that increasing the mortality of non-breeding dispersers within settlement areas can lead to the extinction of species and (meta)populations in a subtle way. This is because the areas where dispersers settle are generally unknown or difficult to detect. Consequently, fewer efforts are devoted to the conservation of these sites than to the conservation of breeding territories. Additionally, high mortality rates affecting the floater sector of a population become evident in the breeding sector only after several of years, when it is too difficult or too late to halt the decline. As a result, because most conservation projects on endangered species and populations mainly focus on breeding areas, many current efforts may be wasted in locations other than those in which conservation would be really necessary and effective.

The eye in systemic sepsis

Metastatic or endogenous endophthalmitis (EE) is a serious consequence of systemic sepsis. It is defined as intraocular infection resulting from haematogenous spread of organisms in which the initial focus of infection is at a site distal to the eye. A red/sore eye in a patient with a known septic focus needs urgent attention as EE can be a major cause of visual loss. Early diagnosis and treatment are associated with better visual outcome. This article focuses on the two main causes of EE, namely bacterial and fungal infections, and also briefly mentions dissemination of cytomegalovirus to the eye in immunocompromised patients. Although conscious patients may notice an ocular problem, unconscious or very sick patients may not; vigilance by medical staff in looking for early signs of this is extremely important.