Reading ability and reading engagement in older adults with glaucoma

PURPOSE

We evaluated the impact of glaucoma-related vision loss on reading ability and reading engagement in 10 reading activities.

METHODS

A total of 63 glaucoma patients and 59 glaucoma suspect controls self-rated their level of reading difficulty for 10 reading items, and responses were analyzed using Rasch analysis to determine reading ability. Reading engagement was assessed by asking subjects to report the number of days per week they engaged in each reading activity. Reading restriction was determined as a decrement in engagement.

RESULTS

Glaucoma subjects more often described greater reading difficulty than controls for all tasks except puzzles (P < 0.05). The most difficult reading tasks involved puzzles, books, and finances, while the least difficult reading tasks involved notes, bills, and mail. In multivariable weighted least squares regression models of Rasch-estimated person measures of reading ability, less reading ability was found for glaucoma patients compared to controls (β = -1.60 logits, P < 0.001). Among glaucoma patients, less reading ability was associated with more severe visual field (VF) loss (β = -0.68 logits per 5-dB decrement in better-eye VF mean deviation [MD], P < 0.001) and contrast sensitivity (β = -0.76 logits per 0.1-unit lower log CS, P < 0.001). Each 5-dB decrement in the better-eye VF MD was associated with book reading on 18% fewer days (P = 0.003) and newspaper reading on 10% fewer days (P = 0.008). No statistically significant reading restriction was observed for other reading activities (P > 0.05).

CONCLUSIONS

Glaucoma patients have less reading ability and engage less in a variety of different reading activities, particularly those requiring sustained reading. Future work should evaluate the mechanisms underlying reading disability in glaucoma to determine how patients can maintain reading ability and engagement.

Low vision depression prevention trial in age-related macular degeneration: a randomized clinical trial

PURPOSE

To compare the efficacy of behavior activation (BA) + low vision rehabilitation (LVR) with supportive therapy (ST) + LVR to prevent depressive disorders in patients with age-related macular degeneration (AMD).

DESIGN

Single-masked, attention-controlled, randomized, clinical trial with outcome assessment at 4 months.

PARTICIPANTS

Patients with AMD and subsyndromal depressive symptoms attending retina practices (n = 188).

INTERVENTIONS

Before randomization, all subjects had 2 outpatient LVR visits, and were then randomized to in-home BA+LVR or ST+LVR. Behavior activation is a structured behavioral treatment that aims to increase adaptive behaviors and achieve valued goals. Supportive therapy is a nondirective, psychological treatment that provides emotional support and controls for attention.

MAIN OUTCOME MEASURES

The Diagnostic and Statistical Manual IV defined depressive disorder based on the Patient Health Questionnaire-9 (primary outcome), Activities Inventory, National Eye Institute Vision Function Questionnaire-25 plus Supplement (NEI-VFQ), and NEI-VFQ quality of life (secondary outcomes).

RESULTS

At 4 months, 11 BA+LVR subjects (12.6%) and 18 ST+LVR subjects (23.4%) developed a depressive disorder (relative risk [RR], 0.54; 95% CI, 0.27-1.06; P = 0.067). In planned adjusted analyses the RR was 0.51 (95% CI, 0.27-0.98; P = 0.04). A mediational analysis suggested that BA+LVR prevented depression to the extent that it enabled subjects to remain socially engaged. In addition, BA+LVR was associated with greater improvements in functional vision than ST+LVR, although there was no significant between-group difference. There was no significant change or between-group difference in quality of life.

CONCLUSIONS

An integrated mental health and low vision intervention halved the incidence of depressive disorders relative to standard outpatient LVR in patients with AMD. As the population ages, the number of persons with AMD and the adverse effects of comorbid depression will increase. Promoting interactions between ophthalmology, optometry, rehabilitation, psychiatry, and behavioral psychology may prevent depression in this population.

Personality and Functional Vision in Older Adults with Age-Related Macular Degeneration

Introduction

The purpose of the study was to determine whether personality traits influence self-reported functional vision in patients with age-related macular degeneration (AMD).

Methods

This is a prospective cross-sectional analysis of baseline data from the Low Vision Depression Prevention Trial. Participants ( N = 182) over age 65 with bilateral AMD, visual acuity worse than 20/70 in the better-seeing eye, and subthreshold depression were recruited from the Wills Eye Hospital retina practice. Assessments included visual acuity, contrast sensitivity, National Eye Institute Visual Function Questionnaire–25 plus Supplement (NEI VFQ–25) near and distance subscales, depression, and personality testing. Structural equation models were used to investigate the relationship of the NEI VFQ near activities and distance activities with the various demographic, clinical, and psychological predictors.

Results

In the single-predictor model for near functional vision, visual acuity at logMAR ≤ 1 (estimate = −0.33 [95% confidence interval {CI} −0.46, −0.20]; p ≤ 0.001), neuroticism (estimate = −0.05 [95% CI −0.08, −0.01]; p = 0.01), and education (estimate = −0.08 [95% CI 0.01, 0.15]; p = 0.03) were statistically significant predictors. In the single-predictor model for distance functional vision, only visual acuity at logMAR ≤ 1 (estimate = −0.49 [95% CI −0.69, −0.29]; p ≤ 0.001) and neuroticism (estimate = −0.09 [95% CI −0.15, 0.02]; p = 0.008) were statistically significant predictors. Discussion: Self-reported functional vision depends on the severity of vision loss as well as the personality trait of neuroticism.

Implications for practitioners

Assessment of personality traits, particularly neuroticism, may increase the precision of rating scales of functional vision and suggest new rehabilitative interventions to improve the functional vision and quality of life of patients with AMD.

Responsiveness of the EQ-5D to the effects of low vision rehabilitation

PURPOSE

This study is an evaluation of the responsiveness of preference-based outcome measures to the effects of low vision rehabilitation (LVR). It assesses LVR-related changes in EQ-5D utilities in patients who exhibit changes in Activity Inventory (AI) measures of visual ability.

METHODS

Telephone interviews were conducted on 77 low-vision patients out of a total of 764 patients in the parent study of "usual care" in LVR. Activity Inventory results were filtered for each patient to include only goals and tasks that would be targeted by LVR.

RESULTS

The EQ-5D utilities have weak correlations with all AI measures but correlate best with AI goal scores at baseline (r = 0.48). Baseline goal scores are approximately normally distributed for the AI, but EQ-5D utilities at baseline are skewed toward the ceiling (median, 0.77). Effect size for EQ-5D utility change scores from pre- to post-LVR was not significantly different from zero. The AI visual function ability change scores corresponded to a moderate effect size for all functional domains and a large effect size for visual ability measures estimated from AI goal ratings.

CONCLUSIONS

This study found that the EQ-5D is unresponsive as an outcome measure for LVR and has poor sensitivity for discriminating low vision patients with different levels of ability.

Fear of falling in age-related macular degeneration

Background

Prior studies have shown age-related macular degeneration (AMD) to be associated with falls. The purpose of this study is to determine if (AMD) and AMD-related vision loss are associated with fear of falling, an important and distinct outcome.

Methods

Sixty-five persons with AMD with evidence of vision loss in one or both eyes and 60 glaucoma suspects with normal vision completed the University of Illinois at Chicago Fear of Falling questionnaire. Responses were Rasch analyzed. Scores were expressed in logit units, with lower scores demonstrating lesser ability and greater fear of falling.

Results

Compared to glaucoma suspect controls, AMD subjects had worse visual acuity (VA) (median better-eye VA = 20/48 vs. 20/24, p < 0.001) and worse contrast sensitivity (CS) (binocular CS = 1.9 vs. 1.5 log units, p < 0.001). AMD subjects were also older, more likely to be Caucasian, and less likely to be employed (p < 0.05 for all), but were similar with regards to other demographic and health measures. In multivariable models controlling for age, gender, body habitus, strength, and comorbid illnesses, AMD subjects reported greater fear of falling as compared to controls (β = -0.77 logits, 95% CI = -1.5 to -0.002, p = 0.045). In separate multivariable models, fear of falling increased with worse VA (β = -0.15 logits/1 line decrement, 95% CI = -0.28 to -0.03, p = 0.02) and CS (β = -0.20 logits/0.1 log unit decrement, 95% CI = -0.31 to -0.09, p = 0.001). Greater fear of falling was also associated with higher BMI, weaker grip, and more comorbid illnesses (p < 0.05 for all).

Conclusions

AMD and AMD-related vision loss are associated with greater fear of falling in the elderly. Development, validation, and implementation of methods to address falls and fear of falling for individuals with vision loss from AMD are important goals for future work.

Improving function in age-related macular degeneration: a randomized clinical trial

PURPOSE

To compare the efficacy of problem-solving therapy (PST) with supportive therapy (ST) to improve targeted vision function (TVF) in age-related macular degeneration (AMD).

DESIGN

Single-masked, attention-controlled, randomized clinical trial with outcome assessments at 3 months (main trial endpoint) and 6 months (maintenance effects).

PARTICIPANTS

Patients with AMD (n = 241) attending retina practices.

INTERVENTIONS

Whereas PST uses a structured problem-solving approach to reduce vision-related task difficulty, ST is a standardized attention-control treatment.

MAIN OUTCOME MEASURES

We assessed TVF, the 25-item National Eye Institute Vision Function Questionnaire plus Supplement (NEI VFQ), the Activities Inventory (AI), and vision-related quality of life (QoL).

RESULTS

There were no between-group differences in TVF scores at 3 (P = 0.47) or 6 (P = 0.62) months. For PST subjects, mean ± standard deviation TVF scores improved from 2.71±0.52 at baseline to 2.18±0.88 at 3 months (P = 0.001) and were 2.18±0.95 at 6 months (change from 3 to 6 months, P = 0.74). For ST subjects, TVF scores improved from 2.73±0.52 at baseline to 2.14±0.96 at 3 months (P = 0.001) and were 2.15±0.96 at 6 months (change from 3 to 6 months, P = 0.85). Similar proportions of PST and ST subjects had less difficulty performing a TVF goal at 3 months (77.4% vs 78.6%, respectively; P = 0.83) and 6 months (76.2% vs 79.1%, respectively; P = 0.61). There were no changes in the NEI VFQ or AI. Vision-related QoL improved for PST relative to ST subjects at 3 months (F(4, 192) = 2.46; P = 0.05) and at 6 months (F(4, 178) = 2.55; P = 0.05). The PST subjects also developed more adaptive coping strategies than ST subjects.

CONCLUSIONS

We found that PST was not superior to ST at improving vision function in patients with AMD, but that PST improved their vision-related QoL. Despite the benefits of anti-vascular endothelial growth factor treatments, AMD remains associated with disability, depression, and diminished QoL. This clinical reality necessitates new rehabilitative interventions to improve the vision function and QoL of older persons with AMD.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Driving patterns in older adults with glaucoma

Background

The ability to drive is important for ensuring quality of life for many older adults. Glaucoma is prevalent in this age group and may affect driving. The purpose of this study is to determine if glaucoma and glaucomatous visual field (VF) loss are associated with driving cessation, limitations, and deference to another driver in older adults.

Methods

Cross-sectional study. Eighty-one glaucoma subjects and 58 glaucoma suspect controls between age 60 and 80 reported if they had ceased driving, limited their driving in various ways, or preferred another to drive.

Results

Twenty-three percent of glaucoma subjects and 6.9% of suspects had ceased driving (p = 0.01). Glaucoma subjects also had more driving limitations than suspects (2.0 vs. 1.1, p = 0.007). In multivariable models, driving cessation was more likely for glaucoma subjects as compared to suspects (OR = 4.0; 95% CI = 1.1-14.7; p = 0.03). The odds of driving cessation doubled with each 5 decibel (dB) decrement in the better-eye VF mean deviation (MD) (OR = 2.0; 95% CI = 1.4-2.9; p < 0.001). Glaucoma subjects were also more likely than suspects to report a greater number of driving limitations (OR = 4.7; 95% CI = 1.3-16.8; p = 0.02). The likelihood of reporting more limitations increased with the VF loss severity (OR = 1.6 per 5 dB decrement in the better-eye VF MD; 95% CI = 1.1-2.4; p = 0.02). Neither glaucoma nor VF MD was associated with other driver preference (p > 0.1 for both).

Conclusions

Glaucoma and glaucomatous VF loss are associated with greater likelihood of driving cessation and greater limitation of driving in the elderly. Further prospective study is merited to assess when and why people with glaucoma change their driving habits, and to determine if their observed self-regulation of driving is adequate to ensure safety.

A general theoretical framework for interpreting patient-reported outcomes estimated from ordinally scaled item responses

A simple theoretical framework explains patient responses to items in rating scale questionnaires. Fixed latent variables position each patient and each item on the same linear scale. Item responses are governed by a set of fixed category thresholds, one for each ordinal response category. A patient's item responses are magnitude estimates of the difference between the patient variable and the patient's estimate of the item variable, relative to his/her personally defined response category thresholds. Differences between patients in their personal estimates of the item variable and in their personal choices of category thresholds are represented by random variables added to the corresponding fixed variables. Effects of intervention correspond to changes in the patient variable, the patient's response bias, and/or latent item variables for a subset of items. Intervention effects on patients' item responses were simulated by assuming the random variables are normally distributed with a constant scalar covariance matrix. Rasch analysis was used to estimate latent variables from the simulated responses. The simulations demonstrate that changes in the patient variable and changes in response bias produce indistinguishable effects on item responses and manifest as changes only in the estimated patient variable. Changes in a subset of item variables manifest as intervention-specific differential item functioning and as changes in the estimated person variable that equals the average of changes in the item variables. Simulations demonstrate that intervention-specific differential item functioning produces inefficiencies and inaccuracies in computer adaptive testing.

Measurements of street-crossing decision-making in pedestrians with low vision

PURPOSE

Crossing the street is an important but risky activity of daily living. If a pedestrian makes a poor street-crossing decision, the consequence could be serious injury or death. In order to advance our understanding of how visual and auditory information is sampled and processed to make street-crossing decisions, an accurate, reliable, and sensitive psychophysical and/or psychometric method of measurement of the street-crossing decision variable must first be developed and validated. The aim of this paper is to develop and validate a new metric for this variable.

METHODS

Using a 5 point rating scale, safety ratings for eight different vehicular gap times of different durations were recorded along an unsignalized, two-lane street of one-way traffic. Safety ratings were collected from 12 normally sighted and 10 visually impaired subjects. Receiver Operating Characteristic (ROC) curves were estimated for all possible gap pairs and the discriminability (d') of the street-crossing decision variable for all gap pairs was estimated from the area under the ROC curve.

RESULTS

We found that our data conform with the assumptions that the underlying distributions of the decision variable are continuous, monotonic and unbounded. Using the dissimilarity matrix of d' values for each person (which were computed for all pairings of gap times) in a one-dimensional scaling model, we estimated the means of each distribution of the decision variable relative to a center of gravity (COG) for the person. When plotting the means of the distributions against vehicular gap time, the data are best described as a non-linear function symmetric about the COG. We showed that the x-intercept (t(COG)) and slope from the non-linear function can be used to assess a person's street-crossing decision-making performance for different amounts of sensory information. Using our newly developed metrics, we found no significant difference in t(COG) (p=0.30) and in the slopes of the model (p=0.85) between normally sighted and visually impaired subjects. In addition, both subject groups centered their t(COG) close to their actual crossing time.

CONCLUSIONS

A newly developed model for measuring a street-crossing decision variable functions as a valid metric that can be used to quantify street-crossing decision-making performance in pedestrians. Using this new metric, we observed that visually impaired subjects who travel independently are able to make street-crossing judgments that are comparable to those of normally sighted subjects.

Baseline traits of low vision patients served by private outpatient clinical centers in the United States

OBJECTIVE

To characterize the traits of low vision patients who seek outpatient low vision rehabilitation (LVR) services in the United States.

METHODS

In a prospective observational study, we enrolled 764 new low vision patients seeking outpatient LVR services from 28 clinical centers in the United States. Before their initial appointment, multiple questionnaires assessing daily living and vision, physical, psychological, and cognitive health states were administered by telephone. Baseline clinical visual impairment measures and disorder diagnoses were recorded.

RESULTS

Patients had a median age of 77 years, were primarily female (66%), and had macular disease (55%), most of which was nonneovascular age-related macular degeneration. More than one-third of the patients (37%) had mild vision impairment with habitual visual acuity (VA) of 20/60 or greater. The VA correlated well with contrast sensitivity (r = -0.52) but poorly with self-reported vision quality. The intake survey revealed self-reported physical health limitations, including decreased endurance (68%) and mobility problems (52%). Many patients reported increased levels of frustration (42%) and depressed mood (22%); memory and cognitive impairment (11%) were less frequently endorsed. Patients relied on others for daily living support (87%), but many (31%) still drove.

CONCLUSIONS

Most patients seeking LVR are geriatric and have macular disease with relatively preserved VA. The disparity between VA and subjective quality of vision suggests that LVR referrals are based on symptoms rather than on VA alone. Patients seen for LVR services have significant physical, psychological, and cognitive disorders that can amplify vision disabilities and decrease rehabilitation potential.

VA LOVIT II: a protocol to compare low vision rehabilitation and basic low vision

PURPOSE

To compare the effectiveness of low vision rehabilitation (LVR) and basic low vision (LV) in a single masked multicentre randomised controlled trial (RCT).

METHODS

Three hundred and thirty patients eligible for US. Veterans Affairs (VA) healthcare services with primary eye diagnosis (better-seeing eye) of macular disease and best-corrected distance visual acuity of 0.40-1.00 logMAR (6/15 to 6/60 or 20/50 to 20/200 Snellen) are being enrolled at seven VA facilities. All participants receive an optometric LV examination; and they are eligible to receive the same LV devices that are provided without charge. In LVR, a LV therapist dispenses devices and provides 2 or 3 (1½ to 2½ h) therapy sessions with assigned homework to teach effective use of remaining vision and LV devices. Contact time with the therapist depends upon the devices prescribed and the patient's progress in learning the skills that are taught. In basic LV, devices are dispensed by the optometrist without LV therapy. Contact time for dispensing is one hour or less depending on LV devices prescribed. The primary outcome measure is a comparison of the changes in visual reading ability (estimated from patients' difficulty ratings of reading items on the VA LV VFQ-48 questionnaire) between the treatment and control arms from pre-intervention baseline to 4 months (2 months after completion of treatment). Secondary outcome measures are changes in overall visual ability, visual ability domain scores calculated from subsets of items (mobility, visual information processing and visual motor skills), Short Form-36, and Minnesota Low Vision Reading Test scores. Cost-effectiveness analysis will be conducted using VA LV VFQ-48 scores and QALYS computed from EuroQol scores.

RESULTS

A total of 137 patients representing 41.5% of the study target of 330 patients were randomised from October 2010 to March 2012. Among those 137 patients, mean age was 80.2 (S.D. ± 9.9) years at enrollment; 97.1% of the patients were males; 94.2% were white. Mean best corrected VA was 0.65 (S.D. ± 0.3) logMAR (approximately Snellen 6/27 or 20/90) at baseline.

CONCLUSIONS

LOVIT II is the first multicentre RCT comparing the effectiveness and cost-effectiveness of LVR and basic LV for patients with macular diseases and near normal or moderate levels of visual impairment.

Latent dry eye disease state variable

PURPOSE

Evidence is growing that dry eye represents a common disease process resulting from a number of underlying pathologies that impact the ocular surface and that clinical estimates of dry eye severity reflect the magnitude of a single dry eye disease state variable, Θ. A theory for estimating Θ from scaled clinical observations is developed, and the hypothesis is tested that Θ exists.

METHODS

The theory is developed around three assumptions: (1) a monotonic function unique to each person and indicator maps the indicator onto Θ, (2) between-person differences in mapping functions are random, and (3) observed indicator values include random perturbations. Data recently published by Sullivan and his colleagues were digitized from scatter plots of seven different indicators versus a composite severity score (square root of summed weighted squared indicator scores).

RESULTS

The data were analyzed with a model derived under the specific assumptions that between-person variance in mapping functions is independent of the indicator value and random perturbations in observed indicator values are normally distributed. Tear osmolarity was the most sensitive indicator, and tear breakup time was the least. The distribution of residuals (squared difference between observed and predicted indicator values) agreed with model expectations for all indicators except tear osmolarity, which had larger residuals than expected, and the composite severity score, which had smaller residuals than expected.

CONCLUSIONS

The results are consistent with the existence of a single latent dry eye disease state variable. Only tear osmolarity does not appear to map monotonically and/or unidimensionally onto the latent variable.

Fear of falling and visual field loss from glaucoma

OBJECTIVE

To determine if visual field (VF) loss resulting from glaucoma is associated with greater fear of falling.

DESIGN

Prospective, observational study.

PARTICIPANTS

Fear of falling was compared between 83 glaucoma subjects with bilateral VF loss and 60 control subjects with good visual acuity and without significant VF loss recruited from patients followed up for suspicion of glaucoma.

METHODS

Participants completed the University of Illinois at Chicago Fear of Falling Questionnaire. The extent of fear of falling was assessed using Rasch analysis.

MAIN OUTCOME MEASURES

Subject ability to perform tasks without fear of falling was expressed in logits, with lower scores implying less ability and greater fear of falling.

RESULTS

Glaucoma subjects had greater VF loss than control subjects (median better-eye mean deviation [MD] of -8.0 decibels [dB] vs. +0.2 dB; P<0.001), but did not differ with regard to age, race, gender, employment status, the presence of other adults in the home, body mass index (BMI), grip strength, cognitive ability, mood, or comorbid illness (P ≥ 0.1 for all). In multivariate models, glaucoma subjects reported greater fear of falling as compared with controls (β = -1.20 logits; 95% confidence interval [CI], -1.87 to -0.53; P = 0.001), and fear of falling increased with greater VF loss severity (β = -0.52 logits per 5-dB decrement in the better eye VF MD; 95% CI, -0.72 to -0.33; P<0.001). Other variables predicting greater fear of falling included female gender (β = -0.55 logits; 95% CI, -1.03 to -0.06; P = 0.03), higher BMI (β = -0.07 logits per 1-unit increase in BMI; 95% CI, -0.13 to -0.01; P = 0.02), living with another adult (β = -1.16 logits; 95% CI, -0.34 to -1.99 logits; P = 0.006), and greater comorbid illness (β = -0.53 logits/1 additional illness; 95% CI, -0.74 to -0.32; P<0.001).

CONCLUSIONS

Bilateral VF loss resulting from glaucoma is associated with greater fear of falling, with an impact that exceeds numerous other risk factors. Given the physical and psychological repercussions associated with fear of falling, significant quality-of-life improvements may be achievable in patients with VF loss by screening for, and developing interventions to minimize, fear of falling.

Is the partial credit model a Rasch model?

A balance scale metaphor is offered as a tool for explaining the principles of measurement and for visualizing the internal structure of dichotomous and polytomous Rasch models. The balance scale metaphor is used to guide the derivation of a general polytomous Rasch model and to illustrate the additional assumptions subsequently required to derive the Andrich (1978) rating scale model (RSM) and the Masters (1982) partial credit model (PCM). The metaphor is used to present the argument that the RSM conforms to the rules of measurement, but the PCM has interactions implicit in its structure that violate specific objectivity and sufficiency of raw scores, which challenge its status as a Rasch model. Using the metaphor and a literal interpretation of the narrative description of the PCM by Masters (1982), a new version of the PCM is derived that does conform to the rules of measurement.

Psychological and cognitive determinants of vision function in age-related macular degeneration

OBJECTIVE

To investigate the effect of coping strategies, depression, physical health, and cognition on National Eye Institute Visual Function Questionnaire scores obtained at baseline in a sample of older patients with age-related macular degeneration (AMD) enrolled in the Improving Function in AMD Trial, a randomized controlled clinical trial that compares the efficacy of problem-solving therapy with that of supportive therapy to improve vision function in patients with AMD.

METHODS

Baseline evaluation of 241 older outpatients with advanced AMD who were enrolled in a clinical trial testing the efficacy of a behavioral intervention to improve vision function. Vision function was characterized as an interval-scaled, latent variable of visual ability based on the near-vision subscale of the National Eye Institute Vision Function Questionnaire-25 plus Supplement.

RESULTS

Visual ability was highly correlated with visual acuity. However, a multivariate model revealed that patient coping strategies and cognitive function contributed to their ability to perform near-vision activities independent of visual acuity.

CONCLUSIONS

Patients with AMD vary in their coping strategies and cognitive function and in their visual acuity, and that variability determines patients' self-report of vision function. Understanding patient coping mechanisms and cognition may help increase the precision of vision rating scales and suggest new interventions to improve vision function and quality of life in patients with AMD. Trial Registration  clinicaltrials.gov Identifier: NCT00572039.

The impact of cataract surgery on patients from a low-vision clinic

OBJECTIVE

To evaluate the effects of cataract extraction with intraocular lens implantation (CE-IOL) in low-vision patients.

DESIGN

Prospective, interventional case series.

PARTICIPANTS

Twenty low-vision patients (30 eyes) underwent CE-IOL by 1 surgeon at an academic institution.

METHODS

Pre- and post-CE-IOL visual acuities and responses to a 23-page survey (self-reported functioning in general vision, mobility, illumination, and ability to see faces) were compared.

RESULTS

Sixteen patients had age-related macular degeneration (AMD); 1 patient each had rod-cone dystrophy, oculocutaneous albinism, retinitis pigmentosa, or cerebrovascular accident. The average age was 78 years (range: 53-96 years). Preoperative best-corrected visual acuity (BCVA) ranged from 20/70 to count fingers; postoperative BCVA at 8 weeks was 20/40 to 20/400, with improvement in 25 (83%) eyes of 15 patients, and no change in the rest. The average change in logMAR of BCVA in the 1 eye or in the eye with better preoperative vision in bilateral surgery was an improvement of 0.6 logMAR units (p = 0.0001). Seventeen (85%) patients noted an improvement in visual function and would consent to CE-IOL again. Twelve patients completed the survey pre- and post-CE-IOL at 3 months. More patients could read with a magnifier after surgery. On average, self-reported functioning was improved.

CONCLUSIONS

In this small study, CE-IOL offered subjective and objective benefits to patients from a low vision clinic, many of whom may have been dissuaded from CE-IOL. Most patients had moderately dense cataracts and moderate to advanced AMD, and these features may help form clinical recommendations. Expectations are important to elicit preoperatively. Postoperatively, patients may be more receptive to low-vision services and devices when the prognosis for visual rehabilitation is better.

Improving function in age-related macular degeneration: design and methods of a randomized clinical trial

Age-Related Macular Degeneration (AMD) is the leading cause of severe vision loss in older adults and impairs the ability to read, drive, and live independently and increases the risk for depression, falls, and earlier mortality. Although new medical treatments have improved AMD's prognosis, vision-related disability remains a major public health problem. Improving Function in AMD (IF-AMD) is a two-group randomized, parallel design, controlled clinical trial that compares the efficacy of Problem-Solving Therapy (PST) with Supportive Therapy (ST) (an attention control treatment) to improve vision function in 240 patients with AMD. PST and ST therapists deliver 6 one-hour respective treatment sessions to subjects in their homes over 2 months. Outcomes are assessed masked to treatment assignment at 3 months (main trial endpoint) and 6 months (maintenance effects). The primary outcome is targeted vision function (TVF), which refers to specific vision-dependent functional goals that subjects highly value but find difficult to achieve. TVF is an innovative outcome measure in that it is targeted and tailored to individual subjects yet is measured in a standardized way. This paper describes the research methods, theoretical and clinical aspects of the study treatments, and the measures used to evaluate functional and psychiatric outcomes in this population.

Medicare coverage for vision assistive equipment

Vision loss that cannot be corrected medically, surgically, or by refractive means is considered low vision. Low vision often results in impairment of daily activities, loss of independence, increased risk of fractures, excess health care expense, and reduced physical functioning, quality of life, and life expectancy. Vision rehabilitation can enable more independent functioning for individuals with low vision. The Centers for Medicare and Medicaid Services recognizes the importance of rehabilitation for achieving medically necessary goals but has denied Medicare coverage for vision assistive equipment that is necessary to complete these goals, although they provide coverage for assistive equipment to provide compensation for other disabilities. We believe that this is discriminatory and does not comport with congressional intent. The Centers for Medicare and Medicaid Services should provide coverage for vision assistive equipment, allowing beneficiaries with vision loss to benefit fully from Medicare-covered rehabilitation to achieve the cost-effective results of these services.

A clinically meaningful theory of outcome measures in rehabilitation medicine

Comparative effectiveness research in rehabilitation medicine requires the development and validation of clinically meaningful and scientifically rigorous measurements of patient states and theories that explain and predict outcomes of intervention. Patient traits are latent (unobservable) variables that can be measured only by inference from observations of surrogate manifest (observable) variables. In the behavioral sciences, latent variables are analogous to intensive physical variables such as temperature and manifest variables are analogous to extensive physical variables such as distance. Although only one variable at a time can be measured, the variable can have a multidimensional structure that must be understood in order to explain disagreements among different measures of the same variable. The use of Rasch theory to measure latent trait variables can be illustrated with a balance scale metaphor that has randomly added variability in the weights of the objects being measured. Knowledge of the distribution of the randomly added variability provides the theoretical structure for estimating measures from ordinal observation scores (e.g., performance measures or rating scales) using statistical inference. In rehabilitation medicine, the latent variable of primary interest is the patient's functional ability. Functional ability can be estimated from observations of surrogate performance measures (e.g., speed and accuracy) or self-report of the difficulty the patient experiences performing specific activities. A theoretical framework borrowed from project management, called the Activity Breakdown Structure (ABS), guides the choice of activities for assessment, based on the patient's value judgments, to make the observations clinically meaningful. In the case of low vision, the functional ability measure estimated from Rasch analysis of activity difficulty ratings was discovered to be a two-dimensional variable. The two visual function dimensions are independent of physical limitations and psychological state. To explain outcome measures (latent variable estimated from difficulty ratings), a theory must be developed that explicitly defines how latent variables are related to the observed manifest variables and to each other. The latent variables are categorized as primary variables, which in the case of low vision are the two visual function dimensions, and as effect modifiers, which in the case of low vision are other physical and psychological latent traits of the patients that can influence the outcome measures. Interventions give rise to latent intervention effect variables that can alter the latent primary variables or independently affect the outcome measures. The latent effect modifier variables, in turn, can alter the latent intervention effect variables. Once developed and validated, a theory of this form will predict the rehabilitation potential of individual patients, i.e., the probability of obtaining criterion outcome measures given the observed state of the patient and the choice of interventions.