Reading in the presence of macular disease: a mini-review

No, Bionic Reading does not work

It has recently been claimed that presenting text with the first half of each word printed in bold (as is done in this example), so-called Bionic Reading, facilitates reading. However, empirical tests of this claim are lacking, and theoretically one might expect a cost rather than a benefit. Here I tested participants' reading speed of 100 paragraphs that were presented either in 'Bionic' or in normal font. Statistical analyses revealed no significant difference in reading times between Bionic and normal reading. I conclude that Bionic Reading does not facilitate reading.

Efficacy οf Wet Age-related Macular Degeneration Treatment οn Reading: A Pilot Study Using Eye-movement Analysis

SIGNIFICANCE

Functional vision, as evaluated with silent passage reading speed, improves after anti-vascular endothelial growth factor (anti-VEGF) treatment in patients with wet age-related macular antidegeneration (wAMD), reflecting primarily a concomitant reduction in the number of fixations. Implementing eye movement analysis when reading may better characterize the effectiveness of therapeutic approaches in wAMD.

PURPOSE

This study aimed to evaluate silent reading performance by means of eye fixation analysis before and after anti-VEGF treatment in wAMD patients.

METHODS

Sixteen wAMD patients who underwent anti-VEGF treatment in one eye and visual acuity (VA) better than 0.5 logMAR served as the AMD group. Twenty adults without ocular pathology served as the control group. Central retinal thickness and near VA were assessed at baseline and 3 to 4 months after their first visit. Reading performance was evaluated using short passages of 0.4-logMAR print size. Eye movements were recorded using EyeLink II video eye tracker. Data analysis included computation of reading speed, fixation duration, number of fixations, and percentage of regressions. Frequency distributions of fixation durations were analyzed with ex-Gaussian fittings.

RESULTS

In the AMD group, silent reading speed in the treated eye correlated well with central retinal thickness reduction and improved significantly by an average of 15.9 ± 28.5 words per minute (P = .04). This improvement was accompanied by an average reduction of 0.24 ± 0.38 in fixations per word (P = .03). The corresponding improvement in monocular VA was not statistically significant. Other eye fixation parameters did not change significantly after treatment. No statistically significant differences were found in the control group.

CONCLUSIONS

Visual acuity tests may underestimate the potential therapeutic effects after anti-VEGF treatment in patients with relatively good acuity who are being treated for wAMD. Evaluating silent reading performance and eye fixation parameters may better characterize the effectiveness of therapeutic approaches in wAMD patients.

What Is a Preferred Retinal Locus?

This review examines the concept of the preferred retinal locus (PRL) in patients with macular diseases. Considering monocular and binocular viewing, we (a) explain how to identify the PRL and discuss the pitfalls associated with its measurement, (b) review the current hypotheses for PRL development, (c) assess whether the PRL is the new reference point of the ocular motor system, and discuss (d) the functional and (e) the clinical implications of the PRL. We conclude that the current definition of the PRL is probably incomplete and should incorporate the need to evaluate the PRL in the framework of binocular viewing. We emphasize the need for more research.

Oculomotor changes following learned use of an eccentric retinal locus

People with bilateral central vision loss sometimes develop a new point of oculomotor reference called a preferred retinal locus (PRL) that is used for fixating and planning saccadic eye movements. How individuals develop and learn to effectively use a PRL is still debated; in particular, the time course of learning to plan saccades using a PRL and learning to stabilize peripheral fixation at the desired location. Here we address knowledge limitations through research describing how eye movements change as a person learns to adopt an eccentric retinal locus. Using a gaze-contingent, eye tracking-guided paradigm to simulate central vision loss, 40 participants developed a PRL by engaging in an oculomotor and visual recognition task. After 12 training sessions, significant improvements were observed in six eye movement metrics addressing different aspects involved in learning to use a PRL: first saccade landing dispersion, saccadic re-referencing, saccadic precision, saccadic latency, percentage of useful trials, and fixation stability. Importantly, our analyses allowed separate examination of the stability of target fixation separately from the dispersion and precision of the landing location of saccades. These measures explained 50% of the across-subject variance in accuracy. Fixation stability and saccadic precision showed a strong, positive correlation. Although there was no statistically significant difference in rate of learning, individuals did tend to learn saccadic precision faster than fixation stability. Saccadic precision was also more associated with accuracy than fixation stability for the behavioral task. This suggests effective intervention strategies in low vision should address both fixation stability and saccadic precision.

Altered eye movements during reading under degraded viewing conditions: Background luminance, text blur, and text contrast

Degraded viewing conditions caused by either natural environments or visual disorders lead to slow reading. Here, we systematically investigated how eye movement patterns during reading are affected by degraded viewing conditions in terms of spatial resolution, contrast, and background luminance. Using a high-speed eye tracker, binocular eye movements were obtained from 14 young normally sighted adults. Images of text passages were manipulated with varying degrees of background luminance (1.3-265 cd/m2), text blur (severe blur to no blur), or text contrast (2.6%-100%). We analyzed changes in key eye movement features, such as saccades, microsaccades, regressive saccades, fixations, and return-sweeps across different viewing conditions. No significant changes were observed for the range of tested background luminance values. However, with increasing text blur and decreasing text contrast, we observed a significant decrease in saccade amplitude and velocity, as well as a significant increase in fixation duration, number of fixations, proportion of regressive saccades, microsaccade rate, and duration of return-sweeps. Among all, saccade amplitude, fixation duration, and proportion of regressive saccades turned out to be the most significant contributors to reading speed, together accounting for 90% of variance in reading speed. Our results together showed that, when presented with degraded viewing conditions, the patterns of eye movements during reading were altered accordingly. These findings may suggest that the seemingly deviated eye movements observed in individuals with visual impairments may be in part resulting from active and optimal information acquisition strategies operated when visual sensory input becomes substantially deprived.

Digital Reading with Low Vision: Principles for Selecting Display Size

SIGNIFICANCE

Digital reading devices have become increasingly popular among people with low vision. Because displays come in many sizes ranging from smart watches to large desktop computer displays, it is important to have principles to guide people with low vision in selecting suitable displays for reading.

PURPOSE

The selection of effective digital displays for reading by people with low vision focuses attention on the interacting effects of print size, display size, font, visual acuity, and reading distance. This technical report aims to provide principles for identifying the minimum size of digital displays required for fluent reading by people with low vision.

METHODS

We emphasize two critical factors in selecting an appropriate reading display: angular print size, which should exceed the individual's critical print size, and display size, which should allow at least 13 characters to be presented on each line. Our approach considers a low-vision individual's acuity and preferences for viewing distance and fonts.

RESULTS

Through an illustrative example, we demonstrate how our approach can be used to determine display size for a low-vision individual with 20/200 acuity and central field loss who wants to read at 30-cm viewing distance with the Times Roman font. We have developed a web application based on our recommended approach to provide easy access to our algorithm.

CONCLUSIONS

We provide a procedure to guide the selection of appropriate displays for a wide range of acuities. Our approach can help clinicians in making recommendations for their patients, digital product designers in developing more accessible devices, and low-vision individuals in selecting digital displays for reading.

Steroid Treatment in Macular Edema: A Bibliometric Study and Visualization Analysis

The use of steroids to treat macular edema (ME) is a research hotspot in ophthalmology. We utilized CiteSpace and VOSviewer software to evaluate the Web of Science Core Collection publications and to build visualizing maps to describe the research progress in this topic. There were 3,252 publications for three decades during 1988–2021. The number of studies was low during the first 14 years but has risen consistently in the following two decades. The average publications per year were only 4.8 during 1988–2002, which jumped to 113 per year during 2003–2012, and 227 per year during 2013–2021. These publications came from 83 countries/regions, with the United States, Germany, and Italy leading positions. Most studies were published in Investigative Ophthalmology Visual Science, and Ophthalmology was the most cited journal. We found 9,993 authors, with Bandello F having the most publications and Jonas JB being the most frequently co-cited. According to our research, the most popular keyword is triamcinolone acetonide (TA). Macular edema, diabetic macular edema (DME), retinal vein occlusion (RVO), dexamethasone (DEX), fluocinolone acetonide (FA), and some other keywords were commonly studied in this field. In conclusion, the bibliometric analysis provides a comprehensive overview of steroid hotspots and developmental tendencies in the macular edema study. While anti-VEGF therapy is the first-line treatment for DME and RVO-induced macular edema, steroids implant is a valid option for these DME patients not responding to anti-VEGF therapy and non-DME patients with macular edema. Combined therapy with anti-VEGF and steroid agents is vital for future research.

Binocular visual function and fixational control in patients with macular disease: A review

For normally sighted observers, the centre of the macula—the fovea—provides the sharpest vision and serves as the reference point for the oculomotor system. Typically, healthy observers have precise oculomotor control and binocular visual performance that is superior to monocular performance. These functions are disturbed in patients with macular disease who lose foveal vision. An adaptation to central vision loss is the development of a preferred retinal locus (PRL) in the functional eccentric retina, which is determined with a fixation task during monocular viewing. Macular disease often affects the two eyes unequally, but its impact on binocular function and fixational control is poorly understood. Given that patients’ natural viewing condition is binocular, the aim of this article was to review current research on binocular visual function and fixational oculomotor control in macular disease. Our findings reveal that there is no overall binocular gain across a range of visual functions, although clear evidence exists for subgroups of patients who exhibit binocular summation or binocular inhibition, depending on the clinical characteristics of their two eyes. The monocular PRL of the better eye has different characteristics from that of the worse eye, but during binocular viewing the PRL of the better eye drives fixational control and may serve as the new reference position for the oculomotor system. We conclude that evaluating binocular function in patients with macular disease reveals important clinical aspects that otherwise cannot be determined solely from examining monocular functions, and can lead to better disease management and interventions.

Efficacy of Large Optic Intraocular Lenses in Myopic Eyes with Posterior Segment Pathology

We report a case series of patients with high myopia (axial length 25.04–27.59 mm) diagnosed with cataract and maculopathy who underwent a combined procedure of phacoemulsification with implantation of a large optic intraocular lens (IOL) and intravitreal injection. Six patients with a mean (± standard deviation) age of 73.20 ± 7.19 years received the 7.0-mm optic ASPIRA-aXA IOL (HumanOptics AG, Erlangen, Germany) and intravitreal injection of aflibercept at the end of the surgery. The corrected distance visual acuity (CDVA) improved significantly (p = 0.001) from a preoperative logMAR of 0.87 ± 0.28 logMAR to 0.49 ± 0.18 logMAR at 10 weeks postoperatively. Even though all patients had a persisting central scotoma due to their maculopathy, there was a significant improvement in their subjective quality of life and self-autonomy. Patients reported no postoperative dysphotopsia. During surgery and postoperative examinations, the wide IOL optic permitted an enhanced view of the fundus. The IOLs remained stable after implantation, especially during the intravitreal injection at the end of the surgery. No IOL displacement or shift of the lens was observed. Retinal diseases are sight-threatening and diminish the patient’s quality of life due to reduced visual acuity and visual field defects. When cataract surgery is performed in this patient group, a reduced prognosis can be assumed. Our results show that implantation of the large optic IOL enables a wide view of the fundus during and after surgery without any additional risks or negative effects. It may also reduce the risk of dysphotopsia in cases of IOL decentration in large capsular bags, but comparative studies with a higher number of cases are needed to confirm this. A large rhexis and large IOL optic seem to be advantageous for the retinal surgeon in follow-up surgeries on the posterior segment of the eye.

A comparison of reading, in people with simulated and actual central vision loss, with static text, horizontally scrolling text, and rapid serial visual presentation

Reading with central vision loss (CVL), as caused by macular disease, may be enhanced by presenting text using dynamic formats such as horizontally scrolling text or rapid serial visual presentation (RSVP). The rationale for these dynamic text formats is that they can be read while holding gaze away from the text, potentially supporting reading while using the eccentric viewing strategy. This study was designed to evaluate the practice of reading with CVL, with passages of text presented as static sentences, with horizontal scrolling sentences, or as single-word RSVP. In separate studies, normally sighted participants with a simulated (artificial) central scotoma, controlled by an eye-tracker, or participants with CVL resulting from macular degeneration read passages of text using the eccentric viewing technique. Comprehension was better overall with scrolling text when reading with a simulated CVL, whereas RSVP produced lower overall comprehension and high error rates. Analysis of eye movement behavior showed that participants consistently adopted a strategy of making multiple horizontal saccades on the text itself. Adherence to using eccentric viewing was better with RSVP, but this did not translate into better reading performance. Participants with macular degeneration and an actual CVL also showed the highest comprehension and lowest error rates with scrolling text and the lowest comprehension and highest errors with RSVP. We conclude that scrolling text can support effective reading in people with CVL and has potential as a reading aid.

Mapping the binocular scotoma in macular degeneration

When the scotoma is binocular in macular degeneration (MD), it often obscures objects of interest, causing individuals to miss information. To map the binocular scotoma as precisely as current methods that map the monocular scotoma, we propose an iterative eye-tracker method. Study participants included nine individuals with MD and four age-matched controls. We measured the extent of the monocular scotomata using a scanning laser ophthalmoscope/optical coherence tomography (SLO/OCT). Then, we precisely mapped monocular and binocular scotomata with an eye tracker, while fixation was monitored. Participants responded whenever they detected briefly flashed dots, which were first presented on a coarse grid, and then at manually selected points to refine the shape and edges of the scotoma. Monocular scotomata measured in the SLO and eye tracker are highly similar, validating the eye-tracking method for scotoma mapping. Moreover, all participants used clustered fixation loci corresponding to their dominant preferred fixation locus. Critically, for individuals with binocular scotomata, the binocular map from the eye tracker was consistent with the overlap of the monocular scotoma profiles from the SLO. Thus, eye-tracker-based perimetry offers a reliable and sensitive tool for measuring both monocular and binocular scotomata, unlike the SLO/OCT that is limited to monocular viewing.

Eye Movements in Macular Degeneration

In healthy vision, the fovea provides high acuity and serves as the locus for fixation achieved through saccadic eye movements. Bilateral loss of the foveal regions in both eyes causes individuals to adopt an eccentric locus for fixation. This review deals with the eye movement consequences of the loss of the foveal oculomotor reference and the ability of individuals to use an eccentric fixation locus as the new oculomotor reference. Eye movements are an integral part of everyday activities, such as reading, searching for an item of interest, eye-hand coordination, navigation, or tracking an approaching car. We consider how these tasks are impacted by the need to use an eccentric locus for fixation and as a reference for eye movements, specifically saccadic and smooth pursuit eye movements. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Training to improve temporal processing of letters benefits reading speed for people with central vision loss

Reading is slow and difficult for many people with central vision loss. A previous study showed that the temporal threshold for letter recognition is a major factor limiting reading speed for people with central vision loss. Here, we asked whether the temporal threshold for letter recognition for people with central vision loss could be improved through training and, if so, whether that would benefit reading. Training consisted of six sessions (3000 trials) of recognizing letter trigrams presented at fixation. Trigrams were initially presented at a baseline temporal threshold that was decreased by 0.1 log step when observers' letter recognition accuracies reached 80% or higher for four consecutive blocks. Before and after training, we measured observers' visual acuity, preferred retinal locus for fixation, fixation stability, reading speeds using the rapid serial visual presentation (RSVP) paradigm, the MNREAD Acuity Chart and 100-word passages, the baseline temporal threshold for letter recognition at 80% accuracy, and a visual-span profile. After training, the temporal threshold was decreased by 68%. This improvement was accompanied by a higher RSVP maximum reading speed (but no change in MNREAD and passage reading speeds) and a larger visual span. A mediation analysis showed that the relationship between the temporal threshold and RSVP maximum reading speed was mainly mediated by the information transfer rate (size of visual span/temporal duration). Our results showed that the temporal threshold for letter recognition is amenable to training and can improve RSVP reading speeds, offering a practical means to improve reading speed for people with central vision loss.

The inhibitory effect of word neighborhood size when reading with central field loss is modulated by word predictability and reading proficiency

For normally sighted readers, word neighborhood size (i.e., the total number of words that can be formed from a single word by changing only one letter) has a facilitator effect on word recognition. When reading with central field loss (CFL) however, individual letters may not be correctly identified, leading to possible misidentifications and a reverse neighborhood size effect. Here we investigate this inhibitory effect of word neighborhood size on reading performance and whether it is modulated by word predictability and reading proficiency. Nineteen patients with binocular CFL from 32 to 89 years old (mean ± SD = 75 ± 15) read short sentences presented with the self-paced reading paradigm. Accuracy and reading time were measured for each target word read, along with its predictability, i.e., its probability of occurrence following the two preceding words in the sentence using a trigram analysis. Linear mixed effects models were then fit to estimate the individual contributions of word neighborhood size, predictability, frequency and length on accuracy and reading time, while taking patients' reading proficiency into account. For the less proficient readers, who have given up daily reading as a consequence of their visual impairment, we found that the effect of neighborhood size was reversed compared to normally sighted readers and of higher amplitude than the effect of frequency. Furthermore, this inhibitory effect is of greater amplitude (up to 50% decrease in reading speed) when a word is not easily predictable because its chances to occur after the two preceding words in a specific sentence are rather low. Severely impaired patients with CFL often quit reading on a daily basis because this task becomes simply too exhausting. Based on our results, we envision lexical text simplification as a new alternative to promote effective rehabilitation in these patients. By increasing reading accessibility for those who struggle the most, text simplification might be used as an efficient rehabilitation tool and daily reading assistive technology, fostering overall reading ability and fluency through increased practice.

Reading Performance in Blue Cone Monochromacy: Defining an Outcome Measure for a Clinical Trial

Purpose

Blue cone monochromacy (BCM), a congenital X-linked retinal disease caused by mutations in the OPN1LW/OPN1MW gene cluster, is under consideration for intravitreal gene therapy. Difficulties with near vision tasks experienced by these patients prompted this study of reading performance as a potential outcome measure for a future clinical trial.

Methods

Clinically and molecularly diagnosed patients with BCM (n = 17; ages 15–63 years) and subjects with normal vision (n = 22; ages 18–72 years) were examined with the MNREAD acuity chart for both uniocular and binocular conditions. Parameters derived from the measurements in patients were compared with normal data and also within the group of patients. Intersession, interocular and between-subject variabilities were determined. The frequent complaint of light sensitivity in BCM was examined by comparing results from black text on a white background (regular polarity) versus white on black (reverse polarity) conditions.

Results

MNREAD curves of print size versus reading speed were right-shifted compared with normal in all patients with BCM. All parameters in patients with BCM indicated abnormal reading performance. Intersession variability was slightly higher in BCM than in normal, but comparable with results previously reported for other patients with maculopathies. There was a high degree of disease symmetry in reading performance in this BCM cohort. Reverse polarity showed better reading parameters than regular polarity in 82% of the patients.

Conclusions

MNREAD measures of reading performance in patients with BCM would be a worthy and robust secondary outcome in a clinical trial protocol, given its dual purpose of quantifying macular vision and addressing an important quality of life issue.

Translational Relevance

Assessment of an outcome for a clinical trial.

Assessment of online patient education materials designed for people with age-related macular degeneration

Background

Age-related macular degeneration (AMD) is a chronic eye condition that leads to permanent vision loss in the central visual field. AMD makes reading challenging and inefficient. People with AMD often find it difficult to access, process and understand written patient education materials (PEMs). To promote health literacy, the demands of written PEMs must match the literacy capacities of the target audience. This study aims to evaluate the readability (grade level) and suitability (appropriateness) of online PEMs designed for people with AMD.

Methods

Online PEMs were sourced from websites of national organizations providing patient education materials designed for people with AMD. The Flesch-Kincaid Grade Level formula and the Suitability Assessment of Materials instrument were used to assess the readability and suitability of PEMs. Descriptive statistics were used to compare online PEMs by organization based on national guidelines for readability level (≤ sixth grade) and the recommended suitability score (≥ 70%) for “superior” material.

Results

One hundred online PEMs were evaluated from websites of 16 professional organizations. The mean readability level was 9.3 (range 5.0–16.6). The mean suitability score was 53% (range 18–78%). Only six (6%) of PEMs achieved the recommended guidelines for readability level and suitability score.

Conclusion

The majority of online PEMs designed for people with AMD were written above the recommended readability level, and below the suggested suitability score. To promote health literacy, the demands of written health information must match the reading capacities of the target audience. Heeding to evidence-based guidelines for providing written information to patients with low health literacy and low vision is beneficial for both patients and health care providers. Future research is warranted.

Asymmetries of reading eye movements in simulated central vision loss

Patients with central vision loss are forced to use an eccentric retinal location as a substitute for the fovea, called a preferred retinal locus, or PRL. Clinical studies have shown that patients habitually choose a PRL located either to the left, and/or below the scotoma in the visual field. The position to the right of the scotoma is almost never chosen, even though this would be theoretically more suitable for reading, since the scotoma no longer blocks the upcoming text. In the current study, we tested whether this asymmetry may have an oculomotor basis. Six normally sighted subjects viewed page-like text with a simulated scotoma, identifying embedded numbers in "words" comprising random letters. Subjects trained and tested with three different artificial PRL ("pseudo-PRL," or pPRL) locations: inferior, to the right, or to the left of the scotoma. After several training blocks for each pPRL position, subjects were found to produce reliable oculomotor control. Both reading speed and eye movement characteristics reproduced observations from traditional paradigms such as page-mode reading and RSVP for an advantage for an inferior pPRL. While left and right positions resulted in similar reading speeds, we observed that a right pPRL caused excessively large saccades and more direction switches, exhibiting a zig-zag pattern that developed spontaneously. Thus, we propose that patients' typical avoidance of pPRL positions to the right of their scotoma could have an oculomotor component: the erratic eye motion might potentially negate the perceptual benefit that this pPRL would offer.

Reading in the presence of macular disease: a mini-review

Purpose

Reading is vital to full participation in modern society. To millions of people suffering from macular disease that results in a central scotoma, reading is difficult and inefficient, rendering reading as the primary goal for most patients seeking low vision rehabilitation. The goals of this review paper are to summarize the dependence of reading speed on several key visual and typographical factors and the current methods or technologies for improving reading performance for people with macular disease.

Important findings

In general, reading speed for people with macular disease depends on print size, text contrast, size of the visual span, temporal processing of letters and oculomotor control. Attempts at improving reading speed by reducing the crowding effect between letters, words or lines; or optimizing properties of typeface such as the presence of serifs or stroke‐width thickness proved to be futile, with any improvement being modest at best. Currently, the most promising method to improve reading speed for people with macular disease is training, including perceptual learning or oculomotor training.

Summary

The limitation on reading speed for people with macular disease is likely to be multi‐factorial. Future studies should try to understand how different factors interact to limit reading speed, and whether different methods could be combined to produce a much greater benefit.