The Evaluation of Reading Performance with Minnesota Low Vision Reading Charts in Patients with Age-related Macular Degeneration.

PURPOSE: To evaluate the reading performance using the Minnesota low vision reading (MNREAD) charts, of patients with age-related macular degeneration (AMD) who use low vision aid (LVA) devices.
MATERIALS AND METHODS: This prospective study enrolled 27 patients with AMD. Distance visual acuity (VA) was evaluated with a distance chart designed for patients with low vision. Near vision and reading performance were evaluated with the Turkish version of the MNREAD charts. Unaided vision and vision with LVA devices and high spherical add near glasses was measured. P <0.05 was considered statistically significant.
RESULTS: The mean unaided near VA was 1.05 ± 0.27 log of the minimum angle of resolution (LogMAR). The mean VA with the LVA devices was 0.71 ± 0.41 LogMAR. Reading acuity ranged between 1.15 and 0.21 LogMAR, critical print size was between - 1.2 and 0.2 LogMAR. Maximum reading speeds were between 0 and 103 words/min. The cases are divided into groups in terms of reading speed according to age, gender, diagnosis, and education. Reading speed was negatively correlated to increasing age.
CONCLUSION: MNREAD reading charts can be used to evaluate reading performance in patients with AMD with low vision. The outcomes of the present study indicate that optical correction is adequate for near VA requirements in this patient population. However, optical correction was inadequate for improving reading performance. Appropriate rehabilitation programs can be used to increase reading speed.

Introduction

Solely assessing letter size that can be read for evaluating the near visual acuity (VA) of patients with low vision is inadequate. Reliable and valid text-based reading charts are required to assess reading performance in this patient population.

Minnesota low vision reading (MNREAD) charts are a text-based chart used to evaluate near vision reading performance of the people with normal and low vision.[1] In Turkey, MNREAD reading charts were developed and validated by έdil et al.[2] The reading performance of patients can be also evaluated by calculating reading acuity, critical print size, and maximum reading speed through these charts.

In the present study, we evaluated the reading performance with MNREAD reading charts of patients with age-related macular degeneration (AMD) who wore optical aids for low vision.

Materials and Methods

Fifty eyes of 27 AMD patients with complaints of low vision that cannot be increased by standard optical correction were retrospectively evaluated. All patients underwent an informed consent procedure before the study.

Patients underwent an ophthalmic evaluation including, refraction, slit lamp biomicroscopy of cornea and anterior segment, measurement of intraocular pressure and fundus examination. Data were collected on the duration of low vision, how it affects daily life and what the expectations of patients from the aid device.

After refractive error correction, distant VAs were measured with a distance vision chart specially designed for patients with low vision (test charts for low vision patients; Zeiss, Jena, Germany). Near vision and reading performance were evaluated with the Turkish version of MNREAD reading card.[2] In the MNREAD reading chart, the largest font was arranged as log of the minimum angle of resolution (LogMAR) 1.3 and minimum was – 0.5 LogMAR. It was composed of 19 sentences. The largest print size was 8 M, and the smallest was 0.12 M.

Optical correction of distance was performed with the following systems: The Galileo system (Zeiss, Jena, Germany) which has 1.8 and 2.2 magnification system, the Kepler system with 4 and 4 vario telescopic magnifications, the Schweizer system with Galileo system which has 2.1 and 2.5 magnification and Kepler system with 3 and 4 magnifications. Telescopic glasses with both Kepler and Galileo systems were used for all patients. The Kepler system was used for patients whose VA was below 20/200. Optically, as magnification increases, the visual field constricts. Therefore, even though the vision improvement is better with the Kepler system, the Galileo system was proposed for ease of use in patients who had constricted visual fields.

After near vision correction, in accordance with patient age, near reading was evaluated by placing a chart at 25 cm. Then, the reading distance and magnification power required for the patient was calculated. High power spherical glasses were used for near vision correction in patients with medium-low vision (20/80–20/60).

Near reading caps were used for near vision correction in the patient group with advanced low vision (20/200–20/400) because reading distance was reduced with high power spherical glasses. Best corrected near VAs of patients were measured and reading performances were calculated. Cases were divided into groups according to their level of education, gender, diagnosis, and age.

Reading performance was assessed by calculating reading acuity, critical print size, and reading speed. The same person in the same room performed all tests and at a distance that the patient could see most clearly after the most appropriate optical correction. Misread, skipped words, reading distances, and reading speeds for each patient were noted in the MNREAD follow-up forms. In the present study, the reading performance of low vision patients with AMD who were treated with the aid devices for low vision was evaluated using MNREAD reading charts. The association between reading performance and gender, diagnosis, education, and age were statistically analyzed.

Data were statistical analyzed with SPSS 20 (IBM Corp., New York, NY, USA). Categorical variables were summarized as the number and percentage. Quantitative measurements were summarized as mean and standard deviation. The normal distribution of quantitative measurements was tested with the Kolmogorov–Smirnov test. The Mann–Whitney U-test was used to compare two groups of quantitative measurements, with nonnormal distribution. The Kruskal–Wallis test was used for the general comparison of the numerical measurement of more than two groups. The Mann–Whitney U-test with Bonferroni correction was used to compare the two groups for significance. Spearman correlation was used to evaluate the association between age and reading measurements. A P < 0.05 indicated statistical significance.

Results

The study sample was comprised 27 patients (50 eyes). There were 22 males and 5 females. The mean age was 74.11 ± 9.86 years (range, 46 and 88 years). Fifteen of 27 (55.6%) patients had atrophic AMD, and 12 (44.4%) had exudative AMD. There were four unilateral cases, or the vision level was <0.01 LogMAR, the other eyes were tested with a low vision aid (LVA).

Unaided mean distance VA was 1.03 ± 0.34 LogMAR (range, 1.4–0.5 LogMAR). Mean distance VA with LVA was 0.58 ± 0.53 LogMAR (range, 1.4–0.0 LogMAR). All patients included in this study were examined, and increased distant VA was obtained in 26 (96.3%) patients. The telescopic glasses were recommended to 21 of 27 (77.8%) patients. Nineteen patients (70.4%) were given both telescopic glasses and high spherical near glasses, and five patients (18.5%) were given only high spherical add near glasses.

The Galileo system was provided to nine cases, and the Kepler telescopic system was provided to 12 cases. Five of these glasses were binocular, 16 were monocular.

Distance VA was examined in all cases who presented for near vision examination. Binocular high spherical glasses for near correction were provided for patients with middle-low vision. There were five patients in this group. A maximum + 6.00 D was added in these cases.

The telescopic system was used for near correction in patients with moderate-low vision and extremely low vision (20/200–20/400, respectively). Reading distance is shorter in high spherical add near glasses. Reading caps added telescopic systems were used for near correction in these cases. Without LVA, the mean near VA was 1.05 ± 0.27 LogMAR (range, 1.3–0.6 LogMAR). The mean near VA with LVA was 0.71 ± 0.41 LogMAR (range, 1.3–0.2 LogMAR).

All patients read the Turkish version of MNREAD chart 1 with the LVA. Reading acuity ranged between 0.21 and 1.15 LogMAR, critical print size was between − 1.2 and 0.2 LogMAR and maximum reading speed was between 0 to 103 words/min. Average maximum read speed was 37.67 ± 31.19 words/min. Reading speed was 37.59 ± 40.21 words/min for 1.6 M print size (magazine print size) (0.6 LogMAR) and 19.3 ± 26.0 words/min for 1.0 M print size (newspaper print size) (0.4 LogMAR) [Table 1].

Table 1

Mean and median values of the cases

The patients were divided into groups based on age, gender, diagnosis, and education. Negative correlations were found between age and the number of words per minute. Decreased reading speed was associated with increasing age. No statistically significant difference was observed for the other variables [Tables 2–5].

Table 2

Numerical exchange and median values of the reading measurements by sex

Table 5

Numerical exchange and median values of the reading measurements by age

Discussion

LVA devices can provide increased distance and near VA in patients with decreased vision due to various etiologies that cannot be increased with a standard correction.[3] Almost 60% of cases apply to the low vision center due to reading difficulties.[4] Providing increased near VA in these cases is very important for successful implement of LVA and patient compliance, but it does not meet the expectations of patients. The selection of the system which is necessary to ensure fast and fluent reading for low vision patients cannot be achieved by solely measuring near VA. It is necessary to measure the reading performance, not the letter size, for evaluating the reading fluency. Therefore, text-based logarithmic near vision chart is needed.

The first Turkish version of arithmetic near vision charts were reported by Soytürk et al.[5] At present, the logarithmic chart is recommended for measuring distance and near VA in terms of equivalence and comparability. In our country, the first national chart with a logarithmic array in geometric order using Turkish sentences was formulated by Eðrilmez et al. and corresponded to current international standards.[6]

MNREAD text-based reading charts are used in the evaluation of near VA and performance of patients with normal and low vision.[1] In Turkey, MNREAD reading charts have been developed and validated by İdil et al.[2] MNREAD charts are originally in English but have been validated in several languages.[789] Developing versions in different languages does not mean translating. Reading charts should be prepared specifically for that language and validity and reliability of these charts should also be tested.

Several factors influence reading speed including, weakening in oculomotor control,[10111213] poor fixation stability,[1415] narrowing in visual space,[161718] retardation in the understanding process of information,[19] near VA, contrast sensitivity, and the print size.[202122]

Print size is one of the most important factors affecting reading speed in people with normal and low vision.[2021] Reading performance can be evaluated with the MNREAD reading charts by calculating the reading acuity, critical print size, and maximum reading speed. Reading acuity is described as the smallest print size that patients can read without significant error. Critical print size is the smallest print size that patients can read with maximum reading speed. The maximum reading speed is described as the reading speed, which cannot be limited by the doubling of the print size magnification power can be calculated with these charts according to the print size, which is required by patients. Although MNREAD charts are used for near reading for a distance of 40 cm in routine practices because of their logarithmic design, they are also used for a distance closer than 40 cm for low vision patients.

When MNREAD reading chart is used in normal patients, average reading speed is 153.69 ± 9.52 words/min for adults (range, 176.15–119.85 words/min), 106.26 ± 15.47 words/min for children (range, 126.52–74.68 words/min). Maximum mean reading speed for chart 1 is 191.50 ± 32.19 words/min (range, 283–101 words/min). It was 185.10 ± 20.46 words/min for journal text paragraphs in print size of 1.6 M (0.6 LogMAR, 20/80). Newspaper text paragraphs have been read at 185.45 ± 27.27 words/min for a print size of 1.0 M (0.4 LogMAR-20/50 Snellen).[2]

In this study, reading performance with LVA was calculated in patients with AMD using the MNREAD chart. Average maximum reading speed was found as 37.67 ± 31.19 words/min. Reading speed was 37.59 ± 40.21 words/min for 1.6 M print size (magazine print size) (LogMAR 0.6) and 19.3 ± 26.0 words/min for 1.0 M print size (newspaper print size) (LogMAR 0.4).

The reading performance of glaucoma patients with VA of 0.7 or higher level was evaluated using a Japanese version of the MNREAD chart and reported at 329.9 ± 55.4 letters/min.[23] In normal cases, the reading speed was 363.0 ± 42.9 letters/min.[23] The decreased reading speed in the Japanese study was due to loss of visual field, despite better VA.[23]

Maximum reading speeds with MNREAD chart were reported as 157, 175, 187 words/min (using three different scoring methods) in the cases with stable early AMD with average VA of 6/9 (0.66) by Snellen.[24] Another study reported reading speed was 73 words/min according to MNREAD chart in patients with AMD with a mean VA of 0.93 LogMAR.[25] Fletcher et al. reported reading speed was 112 words/min in patients with mean distance VA of 0.97 LogMAR.[26]

In this study, the reading speed was negatively correlated with age. Both in patients with low vision and 101 healthy volunteers, aged between 20 and 88 years, the reading speed decreased with increasing age.[27] To assess the reading performance, determination of just near reading acuity is inadequate. Reading speeds should also be measured by text-based cards.

A study by Carver reported that reading speed below 80 words/min was considered slow reading, between 80 and 160 words/min was functional reading and above 160 words/min was fluent reading.[28] In the present study, we found that patients cannot read functionally with only using optical LVA and without performing appropriate rehabilitation programs. However, the near VA was satisfactory. In literature, some researchers have reported that the near reading speed decreased significantly in patients with AMD. However, they also reported that reading speed could be increased by eccentric fixation and near reading practice.[29]

Conclusion

In the evaluation of reading performance, MNREAD charts can be used in patients with AMD who have low vision. Measuring the maximum reading speed, critical print size and near VA by MNREAD charts provides an objective evaluation and monitoring in clinical practice. Reading difficulty in patients with low vision can be resolved with the help of appropriate optical devices and optical rehabilitation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Table 3

Numerical exchange and median values of the reading measurements by diagnosis

Table 4

Numerical exchange and median values of the reading measurements by educational status