Severity of vision loss interacts with word-specific features to impact out-loud reading in glaucoma

Impact of Glaucomatous Ganglion Cell Damage on Central Visual Function

Glaucoma, a leading cause of irreversible blindness, is characterized by the progressive loss of retinal ganglion cells (RGCs) and subsequent visual field defects. RGCs, as the final output neurons of the retina, perform key computations underpinning human pattern vision, such as contrast coding. Conventionally, glaucoma has been associated with peripheral vision loss, and thus, relatively little attention has been paid to deficits in central vision. However, recent advancements in retinal imaging techniques have significantly bolstered research into glaucomatous damage of the macula, revealing that it is prevalent even in the early stages of glaucoma. Thus, it is an opportune time to explore how glaucomatous damage undermines the perceptual processes associated with central visual function. This review showcases recent studies addressing central dysfunction in the early and moderate stages of glaucoma. It further emphasizes the need to characterize glaucomatous damage in both central and peripheral vision, as they jointly affect an individual's everyday activities.

MNREAD Reading Vision in Adults With Glaucoma Under Mesopic and Photopic Conditions

Purpose

Despite good photopic visual acuity, glaucoma patients report difficulty performing daily activities under dim light such as reading. Here we investigated the impact of mesopic lighting conditions on reading vision of glaucoma patients.

Methods

The study design included 39 patients with glaucoma and 40 healthy controls. Reading vision was assessed with MNREAD charts under mesopic (2 cd/m2) and photopic (220 cd/m2) conditions. Four reading indexes: maximum reading speed (MRS), critical print size (CPS), reading acuity (RA), and reading accessibility index (ACC) were obtained from the MNREAD test yielding a plot of reading speed versus print size.

Results

Compared to photopic conditions, reading vision of both healthy controls and glaucoma patients significantly decreased under mesopic conditions (P < 0.05). For glaucoma patients (85% with mild or moderate glaucoma), MRS and ACC decreased by six words per minute and 0.1, respectively under mesopic conditions; CPS and RA increased by 0.25 and 0.18 logMAR, respectively. Moreover, under both photopic and mesopic conditions, reading vision of glaucoma patients was significantly worse than that of healthy controls, but the difference was greater under mesopic conditions (P < 0.05) even after controlling for age and visual acuity.

Conclusions

Mesopic conditions make reading more challenging for both healthy controls and glaucoma patients. However, reading in dim light appears to be more burdensome for glaucoma patients. Mesopic reading tests mediated by both cone and rod photoreceptor systems likely provide a more sensitive and comprehensive assessment of a patient's reading impairment than testing under photopic conditions.

Altered Eye Movements During Reading With Simulated Central and Peripheral Visual Field Defects

Purpose

Although foveal vision provides fine spatial information, parafoveal and peripheral vision are also known to be important for efficient reading behaviors. Here we systematically investigate how different types and sizes of visual field defects affect the way visual information is acquired via eye movements during reading.

Methods

Using gaze-contingent displays, simulated scotomas were induced in 24 adults with normal or corrected-to-normal vision during a reading task. The study design included peripheral and central scotomas of varying sizes (aperture or scotoma size of 2°, 4°, 6°, 8°, and 10°) and no-scotoma conditions. Eye movements (e.g., forward/backward saccades, fixations, microsaccades) were plotted as a function of either the aperture or scotoma size, and their relationships were characterized by the best fitting model.

Results

When the aperture size of the peripheral scotoma decreased below 6° (11 visible letters), there were significant decreases in saccade amplitude and velocity, as well as substantial increases in fixation duration and the number of fixations. Its dependency on the aperture size is best characterized by an exponential decay or growth function in log-linear coordinates. However, saccade amplitude and velocity, fixation duration, and forward/regressive saccades increased more or less linearly with increasing central scotoma size in log-linear coordinates.

Conclusions

Our results showed differential impacts of central and peripheral vision loss on reading behaviors while lending further support for the importance of foveal and parafoveal vision in reading. These apparently deviated oculomotor behaviors may in part reflect optimal reading strategies to compensate for the loss of visual information.

Despite Impaired Binocular Function, Binocular Disparity Integration Across the Visual Field Is Spared in Normal Aging and Glaucoma

Purpose

To examine how binocularly asymmetric glaucomatous visual field damage affects binocular disparity processing across the visual field.

Methods

We recruited 18 patients with primary open-angle glaucoma, 16 age-matched controls, and 13 young controls. Participants underwent standard clinical assessments of binocular visual acuity, binocular contrast sensitivity, stereoacuity, and perimetry. We employed a previously validated psychophysical procedure to measure how sensitivity to binocular disparity varied across spatial frequencies and visual field sectors (i.e., with full-field stimuli spanning the central 21° of the visual field and with stimuli restricted to annular regions spanning 0°-3°, 3°-9°, or 9°-21°). We employed measurements with annular stimuli to model different possible scenarios regarding how disparity information is combined across visual field sectors. We adjudicated between potential mechanisms by comparing model predictions to the patterns observed with full-field stimuli.

Results

Perimetry confirmed that patients with glaucoma exhibited binocularly asymmetric visual field damage (P < 0.001). Across participant groups, foveal regions preferentially processed disparities at finer spatial scales, whereas periphery regions were tuned for coarser scales (P < 0.001). Disparity sensitivity also decreased from fovea to periphery (P < 0.001) and across participant groups (Ps < 0.01). Finally, similar to controls, patients with glaucoma exhibited near-optimal disparity integration, specifically at low spatial frequencies (P < 0.001).

Conclusions

Contrary to the conventional view that glaucoma spares central vision, we find that glaucomatous damage causes a widespread loss of disparity sensitivity across both foveal and peripheral regions. Despite these losses, cortical integration mechanisms appear to be well preserved, suggesting that patients with glaucoma make the best possible use of their remaining binocular function.

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.

Foveal crowding appears to be robust to normal aging and glaucoma unlike parafoveal and peripheral crowding

Visual crowding is the inability to recognize a target object in clutter. Previous studies have shown an increase in crowding in both parafoveal and peripheral vision in normal aging and glaucoma. Here, we ask whether there is any increase in foveal crowding in both normal aging and glaucomatous vision. Twenty-four patients with glaucoma and 24 age-matched normally sighted controls (mean age = 65 ± 7 vs. 60 ± 8 years old) participated in this study. For each subject, we measured the extent of foveal crowding using Pelli's foveal crowding paradigm (2016). We found that the average crowding zone was 0.061 degrees for glaucoma and 0.056 degrees for age-matched normal vision, respectively. These values fall into the range of foveal crowding zones (0.0125 degrees to 0.1 degrees) observed in young normal vision. We, however, did not find any evidence supporting increased foveal crowding in glaucoma (p = 0.375), at least in the early to moderate stages of glaucoma. In the light of previous studies on foveal crowding in normal young vision, we did not find any evidence supporting age-related changes in foveal crowding. Even if there is any, the effect appears to be rather inconsequential. Taken together, our findings suggest unlike parafoveal or peripheral crowding (2 degrees, 4 degrees, 8 degrees, and 10 degrees eccentricities), foveal crowding (<0.25 degrees eccentricity) appears to be less vulnerable to normal aging or moderate glaucomatous damage.

Comparison of 10-2 and 24-2C Test Grids for Identifying Central Visual Field Defects in Glaucoma and Suspect Patients

PURPOSE

To compare the ability of 24-2C and 10-2 test grids in measuring visual field global indices, identifying central visual field defects, and facilitating macular structure-function analysis with OCT scans in glaucoma and glaucoma suspect patients.

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

One eye from 131 glaucoma and 57 glaucoma suspect patients recruited from a referral-only, university-based glaucoma clinic.

METHODS

Each subject underwent perimetric testing using 24-2C SITA-Faster and 10-2 SITA-Fast in random order, and Cirrus OCT macular imaging (Ganglion Cell Analysis) for structure-function correlations.

MAIN OUTCOME MEASURES

Visual field global indices (mean deviation, pattern standard deviation, binarized "cluster" pass/fail, and central mean sensitivity), number and proportion of visual field defects, and structure-function concordance with the Cirrus OCT deviation map following visual field location displacement for correspondence with underlying retinal ganglion cell position.

RESULTS

Global indices (mean deviation, pattern standard deviation, and central mean sensitivity) were similar between both grids. The 10-2 detected more defects compared with the 24-2C (P < 0.0001 for all patients, P = 0.006 for glaucoma patients). This was preserved when analyzing the proportion of defects in the central visual field for all patients (P = 0.02) but was not significantly different for glaucoma patients (P = 0.051). The 10-2 identified more central "clusters" of 2+ contiguous points of deficit (P < 0.0001). Structure-function comparisons performed at locations where visual field and OCT test locations were colocalized revealed greater concordance of structural and functional deficits using the 10-2 (P < 0.0001). The 10-2 took a median of 201 seconds, and the 24-2C took a median of 154 seconds, corresponding to the different thresholding algorithms.

CONCLUSIONS

The 24-2C and 10-2 test grids return similar global indices of visual field performance and proportionally similar amounts of central visual field loss. The additional points in the 10-2 grid return more "clusters" of defects and a greater rate of structure-function concordance compared with the 24-2C test grid. Thus, the 24-2C can identify the presence of a clustered central visual field defect using similar probability criteria, whereas the 10-2 may be more useful in comprehensively characterizing the defect and predicting central visual function.

Rationale and protocol for the 7- and 8-year longitudinal assessments of eye health in a cohort of young adults in the Raine Study

INTRODUCTION

Eye diseases and visual impairment more commonly affect elderly adults, thus, the majority of ophthalmic cohort studies have focused on older adults. Cohort studies on the ocular health of younger adults, on the other hand, have been few. The Raine Study is a longitudinal study that has been following a cohort since their birth in 1989-1991. As part of the 20-year follow-up of the Raine Study, participants underwent a comprehensive eye examination. As part of the 27- and 28-year follow-ups, eye assessments are being conducted and the data collected will be compared with those of the 20-year follow-up. This will provide an estimate of population incidence and updated prevalence of ocular conditions such as myopia and keratoconus, as well as longitudinal change in ocular parameters in young Australian adults. Additionally, the data will allow exploration of the environmental, health and genetic factors underlying inter-subject differential long-term ocular changes.

METHODS AND ANALYSIS

Participants are being contacted via telephone, email and/or social media and invited to participate in the eye examination. At the 27-year follow-up, participants completed a follow-up eye screening, which assessed visual acuity, autorefraction, ocular biometry and ocular sun exposure. Currently, at the 28-year follow-up, a comprehensive eye examination is being conducted which, in addition to all the eye tests performed at the 27-year follow-up visit, includes tonometry, optical coherence tomography, funduscopy and anterior segment topography, among others. Outcome measures include the incidence of refractive error and pterygium, an updated prevalence of these conditions, and the 8-year change in ocular parameters.

ETHICS AND DISSEMINATION

The Raine Study is registered in the Australian New Zealand Clinical Trials Registry. The Gen2 20-year, 27-year and 28-year follow-ups are approved by the Human Research Ethics Committee of the University of Western Australia. Findings resulting from the study will be published in health or medical journals and presented at conferences.

TRIAL REGISTRATION NUMBER

ACTRN12617001599369; Active, not recruiting.

Reading Ability in Primary Open-angle Glaucoma: Evaluation with Radner Reading Charts

SIGNIFICANCE

This study determined the impact of visual disabilities caused by glaucoma on the patient's everyday life and emphasized the importance of developing strategies to improve reading ability in primary open-angle glaucoma (POAG) patients.

PURPOSE

The purposes of this study were to investigate the reading performances of patients affected by POAG using the Italian version of the Radner Reading Charts and to test the presence of correlation between visual field (VF) damage and reading parameters.

METHODS

In this cross-sectional observational study, all patients underwent a complete ophthalmic evaluation including VF testing and evaluation of reading performance using the Radner Reading Charts. The parameters for testing reading performance were reading acuity in logRAD, reading speed in words per minute, maximum reading speed, critical print size, and reading mistakes. Primary open-angle glaucoma and healthy groups were compared using the Mann-Whitney U test. The correlation between VF and reading parameters in glaucomatous eyes was assessed using Spearman correlation analysis. Based on VF mean deviation, each POAG patient had differences in reading performance between his/her best and worst eyes when compared using the paired Wilcoxon test. Statistical significance was set at P ≤ .05.

RESULTS

Eighty POAG patients and 60 healthy controls were enrolled. Glaucomatous subjects read slowly (166.63 ± 29.40 vs. 193.84 ± 26.20 words per minute, P < .0001) and made more mistakes than did healthy subjects. The critical print size for POAG patients was larger than the one for controls (0.52 ± 0.18 vs. 0.62 ± 0.16, P < .0001). Reading parameters showed a moderate correlation with VF mean deviation. The reading parameters were significantly impaired in the worst eye, and this result confirms the impact of VF loss on reading ability.

CONCLUSIONS

This study demonstrated that glaucomatous patients read slowly and with more errors. Reading performances showed a good correlation with VF defect.

Beyond intraocular pressure: Optimizing patient-reported outcomes in glaucoma

Glaucoma, an irreversible blinding condition affecting 3-4% adults aged above 40 years worldwide, is set to increase with a rapidly aging global population. Raised intraocular pressure (IOP) is a major risk factor for glaucoma where the treatment paradigm is focused on managing IOP using medications, laser, or surgery regimens. However, notwithstanding IOP and other clinical parameters, patient-reported outcomes, including daily functioning, emotional well-being, symptoms, mobility, and social life, remain the foremost concerns for people being treated for glaucoma. These outcomes are measured using objective patient-centered outcome measures (PCOMs) and subjective patient-reported outcome measures (PROMs). Studies using PCOMs have shown that people with glaucoma have several mobility, navigational and coordination challenges; reading and face recognition deficits; and are slower in adapting to multiple real-world situations when compared to healthy controls. Similarly, studies have consistently demonstrated, using PROMs, that glaucoma substantially and negatively impacts on peoples' self-reported visual functioning, mobility, independence, emotional well-being, self-image, and confidence in healthcare, compared to healthy individuals, particularly in those with late-stage disease undergoing a heavy treatment regimen. The patient-centred effectiveness of current glaucoma treatment paradigms is equivocal due to a lack of well-designed randomized controlled trials; short post-treatment follow-up periods; an inappropriate selection or availability of PROMs; and/or an insensitivity of currently available PROMs to monitor changes especially in patients with newly diagnosed early-stage glaucoma. We provide a comprehensive, albeit non-systematic, critique of the psychometric properties, limitations, and recent advances of currently available glaucoma-specific PCOMs and PROMs. Finally, we propose that item banking and computerized adaptive testing methods can address the multiple limitations of paper-pencil PROMs; customize their administration; and have the potential to improve healthcare outcomes for people with glaucoma.

Correlation Between Visual Function and Performance of Simulated Daily Living Activities in Glaucomatous Patients

PURPOSE

To analyze the correlations between functional clinical tests and the performance of glaucoma patients in simulated daily living activities.

PATIENTS AND METHODS

Thirty-two patients with chronic glaucoma, followed at the Quinze-Vingts National Ophthalmology Hospital, were included. All patients had a clinical evaluation of visual function including best-corrected visual acuity, contrast sensitivity, and monocular and binocular visual field (VF) tests. Four different simulated activities of daily living were evaluated in standardized artificial platforms (StreetLab and HomeLab): "mobility" and an obstacle avoidance task in an artificial street, "reaching and grasping" large and small objects on a kitchen work surface, "localization of people" and "face orientation recognition." Patient performance in the different tasks was correlated with VF evaluation including integrated binocular visual field (IVF), VF mean deviation (MD) of the better and the worse eye, Esterman binocular VF, best-corrected visual acuity, and contrast sensitivity.

RESULTS

The IVF score was significantly correlated with "localization of people" time (r=0.49; P=0.003), "face orientation recognition" time (r=0.50; P=0.002), and "movement onset" for reaching and grasping small objects (r=0.38; P=0.029). The MD of the better eye appeared significantly correlated with "face orientation recognition" time (r=-0.44; P=0.009) and "localization of people" time (r=-0.46; P=0.005). The Esterman score appeared significantly correlated with "mobility time" (r=-0.40; P=0.018), "localization of people" (r=-0.37; P=0.030), "face orientation recognition" times (r=-0.39; P=0.024), and "movement onset" for reaching and grasping large objects (r=-0.43; P=0.015).

CONCLUSIONS

The IVF score and the MD of the better eye appeared to better evaluate "reaching and grasping," "face orientation recognition," and "localization of people" simulated tasks, whereas for the "mobility" task, the Esterman VF seemed more useful. The precise evaluation of the glaucoma patient's ability to perform everyday life tasks is complex and may require both monocular and binocular VF tests.

Measuring Disability in Glaucoma

BACKGROUND

Glaucomatous visual field loss can have far-reaching and debilitating consequences on an individual, affecting one's ability to perform many important tasks. Although assessment of glaucoma-related disability constitutes an important part of clinical care, there remains a lack of organized, detailed information on the most suitable methods to capture disability in glaucoma.

PURPOSE

This review details the available methods to measure glaucoma-related disability and highlights important findings from studies utilizing these various methods.

METHODS

The literature was reviewed to identify papers evaluating disability in glaucoma and findings were summarized by research methodology used and area of impairment.

RESULTS

Identified methods for capturing glaucoma-related disability included qualitative descriptions, glaucoma-specific quality of life questionnaires, vision-specific questionnaires, general health questionnaires, functional domain-specific questionnaires, evaluation of task performance, event assessment (ie, falls and motor vehicle accidents), and real-world behavior (ie, daily physical activity). Findings using these methods show a strong relationship between glaucoma and/or glaucoma severity and difficulties with reading, driving, mobility, and other tasks such as prehension and facial recognition. In addition, glaucoma has financial and psychological implications on the patient, and can affect caregivers in some cases as well.

CONCLUSIONS

A wide variety of research tools have been used to characterize the disability resulting from glaucoma. Together, these tools show that glaucoma affects many abilities which are important for independent living. Strengths and limitations of the various research techniques are discussed so that future studies may use the method(s) most suitable for answering the research question posed.

Age factor affects reading acuity and reading speed in attaining text information

AIM

To investigate the effect of age on reading acuity and reading speed in attaining text information in healthy eyes.

METHODS

Reading acuity, critical print size, reading speed and maximum reading speed were measured in groups of 40 children (8 to 12 years old), 40 teenagers (13 to 19 years old), 40 young adults (20 to 39 years old), and 40 adults (40 years old and above) using the Buari-Chen Malay Reading Chart [contextual sentences (CS) set and random words (RW) set] in a cross-sectional study design.

RESULTS

Reading acuity was significantly improved by 0.04 logMAR for both CS set and RW set from children to teenagers, then gradually worsened from young adults to adults (CS set: 0.06 logMAR; RW set: 0.08 logMAR). Critical print size for children showed a significant improvement in teenagers (CS set: 0.14 logMAR; RW set: 0.07 logMAR), then deteriorated from young adults to adults by 0.09 logMAR only for CS set. Reading speed significantly increased from children to teenagers, [CS set: 46.20 words per minute (wpm); RW set: 42.06 wpm], then stabilized from teenagers to young adults, and significantly reduced from young adults to adults (CS set: 28.58 wpm; RW set: 24.44 wpm). Increment and decrement in maximum reading speed measurement were revealed from children to teenagers (CS set: 39.38 wpm; RW set: 43.38 wpm) and from young adults to adults (CS set: 22.26 wpm; RW set: 26.31 wpm) respectively.

CONCLUSION

The reference of age-related findings in term of acuity and speed of reading should be incorporated in clinical practice to enhance reading assessment among healthy eyes population.

Higher Contrast Requirement for Letter Recognition and Macular RGC+ Layer Thinning in Glaucoma Patients and Older Adults

Purpose

Growing evidence suggests the involvement of the macula even in early stages of glaucoma. However, little is known about the impact of glaucomatous macular damage on central pattern vision. Here we examine the contrast requirement for letter recognition and its relationship with retinal thickness in the macular region.

Methods

A total of 40 participants were recruited: 13 patients with glaucoma (mean age = 65.6 ± 6.6 years), 14 age-similar normally sighted adults (59.1 ± 9.1 years), and 13 young normally sighted adults (21.0 ± 2.0 years). For each participant, letter-recognition contrast thresholds were obtained using a letter recognition task in which participants identified English letters presented at varying retinal locations across the central 12° visual field, including the fovea. The macular retinal ganglion cell plus inner plexiform (RGC+) layer thickness was also evaluated using spectral-domain optical coherence tomography (SD-OCT).

Results

Compared to age-similar normal controls, glaucoma patients exhibited a significant increase in letter-recognition contrast thresholds (by 236%, P < 0.001) and a significant decrease in RGC+ layer thickness (by 17%, P < 0.001) even after controlling for age, pupil diameter, and visual acuity. Compared to normal young adults, older adults showed a significant increase in letter-recognition contrast thresholds and a significant decrease in RGC+ layer thickness. Across all subjects, the thickness of macular RGC+ layer was significantly correlated with letter-recognition contrast thresholds, even after correcting for pupil diameter and visual acuity (r = −0.65, P < 0.001).

Conclusions

Our results show that both glaucoma and normal aging likely bring about a thinning of the macular RGC+ layer; the macular RGC+ layer thickness appears to be associated with the contrast requirements for letter recognition in central vision.

Slow Reading in Glaucoma: Is it due to the Shrinking Visual Span in Central Vision?

Purpose

Glaucoma is a leading cause of blindness worldwide, characterized by progressive loss of retinal ganglion cells. Patients with bilateral glaucoma read slower than normal cohorts. Here we examined the factors that may underlie slow reading in glaucoma and determined the best predictor of reading speed in glaucoma.

Methods

A total of 38 subjects participated in this study: 17 patients with primary open-angle glaucoma (mean age = 64.71 years) and 21 age-similar normal controls (58.24 years). For each subject, we measured binocular visual acuity (BVA); binocular contrast sensitivity (BCS); stereoacuity; visual field mean deviation (MD); and the visual span (i.e., the number of letters recognizable at one glance) known to limit reading speed. The visual span was measured with a trigram letter-recognition task in which subjects identify trigrams flashed at varying letter positions left and right of the fixation. Oral reading speed was measured with short blocks of text.

Results

Even after controlling for age, glaucoma patients showed significantly slower reading speed (by 19%, P < 0.05) and smaller visual span (by 11 bits, P < 0.001) compared to normal controls. While their BVA was relatively normal (20/20 Snellen equivalent), their BCS (P < 0.001); stereoacuity (P < 0.001); and visual field MD (P < 0.001) showed pronounced deficits. Multiple regression analysis further revealed that reading speed in glaucoma was best predicted by the visual span.

Conclusions

Our results showed that slower reading speed in glaucoma was closely related to the shrinkage of the visual span. Our findings further support the view that the visual span plays a limiting role in reading speed.

Predicting Vision-Related Disability in Glaucoma

PURPOSE

To present a new methodology for investigating predictive factors associated with development of vision-related disability in glaucoma.

DESIGN

Prospective, observational cohort study.

PARTICIPANTS

Two hundred thirty-six patients with glaucoma followed up for an average of 4.3±1.5 years.

METHODS

Vision-related disability was assessed by the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) at baseline and at the end of follow-up. A latent transition analysis model was used to categorize NEI VFQ-25 results and to estimate the probability of developing vision-related disability during follow-up. Patients were tested with standard automated perimetry (SAP) at 6-month intervals, and evaluation of rates of visual field change was performed using mean sensitivity (MS) of the integrated binocular visual field. Baseline disease severity, rate of visual field loss, and duration of follow-up were investigated as predictive factors for development of disability during follow-up.

MAIN OUTCOME MEASURES

The relationship between baseline and rates of visual field deterioration and the probability of vision-related disability developing during follow-up.

RESULTS

At baseline, 67 of 236 (28%) glaucoma patients were classified as disabled based on NEI VFQ-25 results, whereas 169 (72%) were classified as nondisabled. Patients classified as nondisabled at baseline had 14.2% probability of disability developing during follow-up. Rates of visual field loss as estimated by integrated binocular MS were almost 4 times faster for those in whom disability developed versus those in whom it did not (-0.78±1.00 dB/year vs. -0.20±0.47 dB/year, respectively; P < 0.001). In the multivariate model, each 1-dB lower baseline binocular MS was associated with 34% higher odds of disability developing over time (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.06-1.70; P = 0.013). In addition, each 0.5-dB/year faster rate of loss of binocular MS during follow-up was associated with a more than 3.5 times increase in the risk of disability developing (OR, 3.58; 95% CI, 1.56-8.23; P = 0.003).

CONCLUSIONS

A new methodology for classification and analysis of change in patient-reported quality-of-life outcomes allowed construction of models for predicting vision-related disability in glaucoma.

Impact of Glaucoma and Dry Eye on Text-Based Searching

PURPOSE

We determine if visual field loss from glaucoma and/or measures of dry eye severity are associated with difficulty searching, as judged by slower search times on a text-based search task.

METHODS

Glaucoma patients with bilateral visual field (VF) loss, patients with clinically significant dry eye, and normally-sighted controls were enrolled from the Wilmer Eye Institute clinics. Subjects searched three Yellow Pages excerpts for a specific phone number, and search time was recorded.

RESULTS

A total of 50 glaucoma subjects, 40 dry eye subjects, and 45 controls completed study procedures. On average, glaucoma patients exhibited 57% longer search times compared to controls (95% confidence interval [CI], 26%-96%, P < 0.001), and longer search times were noted among subjects with greater VF loss (P < 0.001), worse contrast sensitivity (P < 0.001), and worse visual acuity (P = 0.026). Dry eye subjects demonstrated similar search times compared to controls, though worse Ocular Surface Disease Index (OSDI) vision-related subscores were associated with longer search times (P < 0.01). Search times showed no association with OSDI symptom subscores (P = 0.20) or objective measures of dry eye (P > 0.08 for Schirmer's testing without anesthesia, corneal fluorescein staining, and tear film breakup time).

CONCLUSIONS

Text-based visual search is slower for glaucoma patients with greater levels of VF loss and dry eye patients with greater self-reported visual difficulty, and these difficulties may contribute to decreased quality of life in these groups.

TRANSLATIONAL RELEVANCE

Visual search is impaired in glaucoma and dry eye groups compared to controls, highlighting the need for compensatory strategies and tools to assist individuals in overcoming their deficiencies.

Functional impairment of reading in patients with dry eye

BACKGROUND/AIMS

To evaluate the impact of dry eye on reading performance.

METHODS

Out-loud and silent reading in patients with clinically significant dry eye (n=41) and controls (n=50) was evaluated using standardised texts. Dry eye measures included tear film break-up time, Schirmer's test and corneal epithelial staining. Symptoms were assessed by the Ocular Surface Disease Index (OSDI).

RESULTS

The dry eye group had a greater proportion of women as compared with the control group but did not differ in age, race, education level or visual acuity (p≥0.05 for all). Out-loud reading speed averaged 148 words per minute (wpm) in dry eye subjects and 163 wpm in controls (p=0.006). Prolonged silent reading speed averaged 199 wpm in dry eye subjects versus 226 wpm in controls (p=0.03). In multivariable regression models, out-loud and sustained silent reading speeds were 10 wpm (95% CI -20 to -1 wpm, p=0.039) and 14% (95% CI -25% to -2%, p=0.032) slower, respectively, in dry eye subjects as compared with controls. Greater corneal staining was associated with slower out-loud (-2 wpm/1 unit increase in staining score, 95% CI =-3 to -0.3 wpm) and silent (-2%, 95% CI -4 to -0.6 wpm) reading speeds (p<0.02 for both). Significant interactions were found between OSDI score and word-specific features (longer and less commonly used words) on out-loud reading speed (p<0.05 for both).

CONCLUSIONS

Dry eye is associated with slower out-loud and silent reading speeds, providing direct evidence regarding the functional impact of dry eye. Reading speed represents a measurable clinical finding that correlates directly with dry eye severity.

On-road Driving Performance of Patients With Bilateral Moderate and Advanced Glaucoma

PURPOSE

To compare on-road driving performance of patients with moderate or advanced glaucoma to controls and evaluate factors associated with unsafe driving.

DESIGN

Case-control pilot study.

METHODS

A consecutive sample of 21 patients with bilateral moderate or advanced glaucoma from Washington University, St Louis, Missouri and 38 community-dwelling controls were enrolled. Participants, aged 55-90 years, underwent a comprehensive clinical evaluation by a trained occupational therapist and an on-road driving evaluation by a masked driver rehabilitation specialist. Overall driving performance of pass vs marginal/fail and number of wheel and/or brake interventions were recorded.

RESULTS

Fifty-two percent of glaucoma participants scored a marginal/fail compared to 21% of controls (odds ratio [OR], 4.1; 95% CI, 1.30-13.14; P = .02). Glaucoma participants had a higher risk of wheel interventions than controls (OR, 4.67; 95% CI, 1.03-21.17; P = .046). There were no differences detected between glaucoma participants who scored a pass vs marginal/fail for visual field mean deviation of the better (P = .62) or worse (P = .88) eye, binocular distance (P = .15) or near (P = .23) visual acuity, contrast sensitivity (P = .28), or glare (P = .88). However, glaucoma participants with a marginal/fail score performed worse on Trail Making Tests A (P = .03) and B (P = .05), right-sided Jamar grip strength (P = .02), Rapid Pace Walk (P = .03), Braking Response Time (P = .03), and identifying traffic signs (P = .05).

CONCLUSIONS

Patients with bilateral moderate or advanced glaucoma are at risk for unsafe driving-particularly those with impairments on psychometric and mobility tests. A comprehensive clinical assessment and on-road driving evaluation is recommended to effectively evaluate driving safety of these patients.