Best-corrected visual acuity does not capture the degree of impairment in some patients, such as those with geographic atrophy, particularly as they try to read across a page. A new patient-reported outcome measure has been found to correlate well with a more objective measurement of performance.
Take-home message: Best-corrected visual acuity does not capture the degree of impairment in some patients, such as those with geographic atrophy, particularly as they try to read across a page. A new patient-reported outcome measure has been found to correlate well with a more objective measurement of performance.
By Laird Harrison; Reviewed by Adnan Tufail, MD
London-A patient-reported outcome measure aimed at capturing the impact of reading impairment correlates well with a more objective measurement of performance, researchers say.
The measurement could be particularly useful in patients with geographic atrophy, said Adnan Tufail, MD, a consultant at Moorfields Eye Hospital in London, United Kingdom. Best-corrected visual acuity (BCVA) does not capture the degree of impairment in these patients fully, he said.
Prof. Tufail presented the finding at the European Society of Retina Specialists 15th EURETINA Congress.
People with geographic atrophy often struggle to read, and this can interfere with many activities of daily living, Prof. Tufail said.
“A patient can see single letters quite well, but you need about 2° of field horizontally to be able to read fluently,” he said. “The letters in front and behind are obscure, so the patient has great difficulty reading fluently and tracking across the page.”
To measure patients’ visual acuity, clinicians can use objective performance outcome measures. And they can use questionnaires that provide insight into the effect of reading impairment on daily life.
To get an idea who these two approaches relate to each other, Prof. Tufail and his colleagues compared them in Mahalo, a randomized sham-controlled, phase 2 trial of the investigational drug lampalizumab for geographic atrophy secondary to age-related macular degeneration.
For the purpose of comparing the measurements of reading ability, they did not distinguish between those patients who received lampalizumab and those who received the sham injection. Instead they pooled data from all 100 English-speaking participants.
The patients received either sham injections or lampalizumab in 1 eye monthly or every other month for 18 months.
The researchers measured the number of words the patients could read per minute (wpm) using MNRead Acuity Charts (Precision Vision, LaSalle, IL) with continuous text representing everyday reading. They defined maximum reading speed as the average of the patient’s 3 highest reading speed values.
They defined reading fluency as at least 80 words per minute (wpm), spot reading as 40 wpm, and highly fluent reading as 160 wpm.
They also administered the 7-item Functional Reading Independence (FRI) Index. In this assessment, they asked the patients about reading involved in such activities as paying bills, taking medicine, shopping, using a telephone, watching television, using a computer, or reading books.
They asked the patients if they had performed the activity during the past 7 days and the extent to which the patient required low vision aids, adjustments in the activity, or help from another person. Scores ranged from 1 (unable to do) to 4 (totally independent). Both reading assessments were binocular and measured at baseline and every 6 months.
At baseline, the patients’ mean age was 80 years. Sixty percent were women. Their geographic atrophy lesions were a mean of 8.9 mm2. The patients’ mean BCVA was 48 EDTRS letters with a Snellen equivalent of 20/125.
The mean baseline maximum reading speed was 104 wpm. This declined to 100 wpm at month 6, 95 at month 12, and 82 at month 18.
“The functional reading independence index has been made freely available for groups interested in looking at outcomes in non-neovascular AMD,” Prof. Tufail said. He advised anyone who is interested to email PROinformation@mapi-trust.org.
Patients who could read more than 80 wpm had a mean FRI Index of 3.0 at baseline and a mean FRI Index of 2.7 at month 18. Patients who could read less than 80 wpm at baseline had an FRI Index of 1.9 at baseline and 1.7 at month 18. These correlations were statistically significant (p <0.0001).