The protocol, baseline characteristics of patients, and ONTT
treatment trial results have been reported
previously.
3 5 10 11 12 13 Briefly, 457 patients between 18 and
46 years of age with acute unilateral optic neuritis and no indication
of a causal systemic disease other than MS were enrolled. The primary
visual outcome from treatment was assessed after 6 months. Patients
continued to be followed yearly to assess visual and neurologic
courses. The study protocol was approved by the Institutional Review
Board at each clinical center. Written informed consent was
obtained from each patient, in adherence with the Declaration of
Helsinki.
Vision tests, all performed with correction of refractive error from a
standardized refraction protocol, included the following: (1) visual
acuity with a retro-illuminated ETDRS chart, (2) contrast
sensitivity with the Pelli–Robson chart, (3) color vision with the
Farnsworth Munsell 100-hue test, and (4) visual field with the Humphrey
Field Analyzer, program 30-2. The normal ranges for visual acuity
(logMar value < 0.0 (better than 20/20) and contrast sensitivity
(≥line 15) were based on normative data collected by the ONTT clinical
centers on subjects in the age range of the ONTT
patients
14 for color vision (error score ≤ 110)
based on published data,
15 and for visual field mean
deviation (≥ −3.00) based on unpublished normative data collected by
the ONTT Visual Field Reading Center at the University of California,
Davis (Johnson C, unpublished observations, January 1991). Each
patient was classified as having zero, one, or two eyes abnormal with
respect to visual acuity.
A diagnosis of clinically definite MS (CDMS) was made when a patient
reported new neurologic symptoms consistent with demyelination, other
than recurrent optic neuritis, lasting more than 24 hours that were
confirmed by the presence of a new neurologic abnormality on
examination.
16 Neurologic disability was assessed using
the Expanded Disability Status Scale (EDSS).
17 Each
patient was classified as follows: no CDMS, CDMS with EDSS < 3,
or CDMS with EDSS ≥ 3.
Between April 1996 and March 1997 (5–8 years from study entry), the
51-item field-test version of the NEI–VFQ was included as part of the
testing at the annual examination of 244 patients who had a study visit
during this 1-year period at one of the study clinical centers. The
major reason for noninclusion of patients (for 167 [78%] of the 213
nonincluded patients) was that they did not have a visit at a study
clinic in the time window in which the NEI–VFQ was administered: 13 of
the patients had moved and had ongoing follow-up by a nonstudy
ophthalmologist, 50 patients discontinued follow-up before the
inclusion of the NEI–VFQ, and 104 were still in follow-up but did not
have a visit during the 12 months it was administered (visit window for
annual visits spanned 16 months). Forty-six (22%) patients had an
examination at a study clinic during the time window of the NEI–VFQ
but did not complete the NEI–VFQ; we did not collect data on whether
the patient refused or the clinic neglected to give the questionnaire
to the patient to complete. The 213 patients who were not included were
similar to the 244 who were included in gender (75% versus 79%
female, P = 0.31) but were slightly younger in age at
the time of entry into ONTT (mean 31 ± 6 versus 33 ± 7, P < 0.01) and were slightly less often white (82%
versus 88%, P = 0.05).
To ease the implementation of the NEI–VFQ in the study, the
questionnaire was self-administered. Clinic staff described the
questionnaire and how it was to be completed. This was reiterated in
written instructions, which preceded the questions.
Subscales, scored 0 to 100 (with 100 indicating highest function), were
generated for overall health, overall vision, difficulty with near
vision activities, difficulty with distance vision activities,
limitations in social functioning due to vision, role limitations due
to vision, dependency due to vision, mental health symptoms due to
vision, future expectations for vision, driving difficulties,
limitations with peripheral and color vision, and pain or discomfort in
or around eyes. For analysis, when one or more items from a subscale
were missing, the subscale was considered missing. Analyses using all
available data (i.e., a subscale score was generated when the subject
responded to one or more items from the subscale) provided similar
results (data not shown). In addition to the 51-item field test version
of the NEI–VFQ, we calculated scores for the 25-item version and
present limited results using this abbreviated version.