·Brief
Report·
Functional
outcome of the low vision aids for visual impairment secondary to central
nervous system tumors in children
Rania GE Zaki, Reham
F. Elshinawy, Karim M. Naguib
Department of Ophthalmology, Faculty of
Medicine,
Correspondence to: Reham F. Elshinawy. 4th District, Area No.3, 5th
Settlement, New
Received:
Abstract
To assess functional outcomes of optical low vision
aids (LVAs) for pediatric visual impairment due to central nervous system (CNS)
tumors. A prospective case study was conducted on 15 children with history of
CNS tumors with mean age of 10.47±1.85y. Lighthouse distance, near visual
acuity tests, cycloplegic refraction, reading speed measurement and visual
field examination were done. Prescription of far and near LVAs followed by
training sessions. LVPrasad-functional vision questionnaire was done to
evaluate performance. Visual impairment was moderate (13.3%), severe (73.3%),
profound (6.7%) and near blindness in 6.7%. Telescopes prescribed in 33.4%,
video magnifier in 46.7%. Questionnaire scores were significantly improved for
distant rather than near tasks (P≤0.05) after training. LVAs rehabilitation
is an effective method of improving vision in pediatric visual defects
secondary to CNS tumors.
KEYWORDS: visual impairment; low vision aids; central nervous
system tumors
DOI:10.18240/ijo.2019.10.19
Citation: Zaki RG, Elshinawy RF, Naguib KM. Functional outcome of the low vision
aids for visual impairment secondary to central nervous system tumors in
children. Int J Ophthalmol
2019;12(10):1643-1648
INTRODUCTION
Pediatric visual impairment is a need territory for
vision 2020. Visual hindrance in youth can influence their psychological,
physical, passionate and neurological development[1-2]. Low vision is defined as visual acuity of less than
6/18 but equivalent to or superior
than 3/60, or a corresponding visual field loss less than 20 degrees, in the
better eye with the best possible correction[3].
Early evaluation with provision and training of low vision aids (LVAs) is
fundamental to enhance practical vision so enabling most kids to enroll in
mainstream schools[4-5].
Central nervous system (CNS) tumors are the most
frequent solid tumors in children and adolescents[6].
Visual impairment associated with pediatric CNS depends on the area, tumor
type, and duration of the disease. Gothwal et al[7]
built up a questionnaire to survey the self-reported functional capacities of
visually impaired children: the
The main goal of the present study was to assess the
functional outcome of the use of optical far and near LVAs for pediatric low
vision with CNS tumors related visual impairment and their impact on
educational abilities.
SUBJECTS AND METHODS
Ethical Approval
This study was completed
in agreement to the fundamentals of the Declaration of Helsinki and performed
according to the recommendations of Faculty of Medicine, Ain Shams University
Research Ethical Committee (FMASU REC; No. FWA000017585). Nature of the study
were disclosed to the guardians in detail and an informed consent was taken.
A prospective case study was conducted on 15 children
with history of CNS tumors with visual impairment. They had completed their
therapy two years before seeking visual rehabilitation with stable medical
condition. They were referred to the pediatric low-vision clinic to evaluate
visual performance according to World Health Organization classification of
visual impairment and for visual rehabilitation[3].
Children less than 6 years old, those with different disabilities as
intellectual impairment, hearing defects and those who utilized optical LVAs
previously were barred from the study.
Full ophthalmic history, detailed ophthalmic
examination, unaided far and near visual acuity (line acuity), refraction
followed by best corrected visual acuity (BCVA) were done. Distance visual
acuity was measured using Lighthouse Distance Visual Acuity Landolt Ring test.
Near visual assessment was done using the Lighthouse near acuity test (THE
LIGHTHOUSE Low Vision Products,
Visual field assessment was carried out by Goldmann
kinetic and static perimetry, using large stimulus (V4-white target) projected
on a 31.8 apostilb (asb) [10 candelas per square meter (cd/m2)]
white background for cooperative children using Oculus Twinfield 2 Analyzer
(Oculus Optikgeräte GmbH, Wetzlar-Dutenhofen city,
For calculation of magnification, the required
magnification (M) for distance=desired visual acuity/actual visual acuity. As
the higher magnification the narrower the field of view, thus the least
effective magnification suitable was prescribed to avoid field restriction.
Starting magnification needed for near vision was calculated from the
lighthouse near acuity test chart used for near vision assessment. This
addition power was then refined and adjusted to be adequate for the child’s
needs by requesting the patient to read a continuous content (school books). In
the wake of picking the proper perusing reading aid, the child’s reading speed
was measured to assess the improvement and to be utilized as a baseline value
to survey the improvement.
For far distance viewing, handheld telescopes and
telescopic systems mounted in glasses were used. Reading aids include high plus
glasses, telescopic systems for near mounted in glasses, clip on lens
magnifiers over glasses, stand magnifiers and electronic magnifiers as video
magnifier pocket viewer.
All children gotten in-office instructional sessions
to acquaint them with the utilizations and restrictions of the optical aids
recommended until the child showed satisfactory expertise. Training for reading
involved; appropriate handling of the aids, optimizing eye movements and
figuring out how to utilize the ideal retinal locus. The main policy of
training for distance vision aids consist of five main items: spotting,
focusing, tracing, tracking, scanning. The previously validated questionnaire
(LVP-FVQ) was translated into Arabic and administered to the child at the first
principle visit and at 3mo after low vision rehabilitation.
The patients were examined 3mo after training for
BCVA for near and far using LVAs and visual function was assessed by
practitioner observations and assessment questionnaire.
Statistical Analysis All data were coded and statistically analyzed using the
SPSS (Social package for statistical science) version 13.0 for windows (SPSS
Inc.,
RESULTS
Study included 15 children with mean age of
10.47±1.85y (range 7.0-14.0y), 11 males (73.3%) and 4 females (26.7%). CNS
tumors of those children were craniopharyngioma (46.7%), optic nerve glioma (26.7%),
ependymoma (6.7%), posterior fossa astrocytoma (6.7%), pituitary tumor (6.7%)
and leukemic cerebral infiltrates (6.7%). All the patients had completed their
tumor therapy two years before seeking visual rehabilitation .
Visual impairment was classified according to BCVA of
the better seeing eye prior to use of far LVAs into: moderate visual impairment
in two patient (13.3%), severe visual impairment in 11 patients (73.3%),
profound in one patient (6.7%) and near blindness in one patient (6.7%).
Prior to the use of LVAs, distance visual acuities
(logMAR) ranged from 0.0 to 2.2, mean distance visual acuity was 1.27±0.31,
near visual acuities (logMAR) ranged from 0.6 to 1.6, mean near acuity
1.25±0.33. Visual acuity of the better seeing eye was equal to or less than 1.3
logMAR in (60%) of patients.
Far vision aids were prescribed according to the
visual acuity and tasks of each patient. Far visual acuities (logMAR) after
LVAs ranged from 0.2 to 1.22; mean distance visual acuity was 0.65±0.37.
Children who received distance LVAs achieved aided distance visual acuity of
Spectacle-mounted Galilean telescopes were the most
frequently used distance LVA. Binocular telescopes were prescribed for seven
patients (46.7%) and monocular telescopes were prescribed for eight patients
(53.3%).
BCVA in the better eye after use of far LVAs was
markedly improved in all patients and classified into: near normal vision in
four patients (26.7%), moderate in eight patients (53.3%) and severe in three
patients (20%). There was a statistically significant improvement in degree of
visual impairment following the use of far LVAs (P=0.019). Table 1
demonstrated the types and effects of use of LVAs on far vision correction.
Table 1 Types and specifications of LVAs used for far
vision, and the BCVA before and after their use
Patient No. |
Far VA at initial visit (logMAR) |
Use of LVAs for far |
Magnification (diopters) |
Far BCVA after use of LVA (logMAR) |
|||
OD |
OS |
OD |
OS |
OD |
OS |
||
1 |
1.3 |
1.3 |
Binocular |
Telemed 3×; working distance |
Telemed 3×; working distance |
0.7 |
0.7 |
2 |
0.92 |
2.5 |
Monocular |
4× telescope Working distance |
- |
0.3 |
- |
3 |
1.3 |
2.4 |
Monocular |
2.5×; working distance
infinity; visual field |
- |
0.7 |
1.3 |
4 |
0.0 |
|
Monocular |
6×; visual field |
- |
0.7 |
- |
5 |
1.3 |
1.0 |
Binocular |
Telemed 4×; working distance |
Telemed 4×; working distance |
0.4 |
0.3 |
6 |
2.2 |
2.5 |
Monocular |
6×; visual field |
- |
1.3 |
- |
7 |
1.3 |
1.3 |
Binocular |
4× telescope; working distance |
4× telescope; working distance |
0.2 |
0.2 |
8 |
1.3 |
2.4 |
Monocular |
6×; visual field |
- |
0.4 |
- |
9 |
1.3 |
1.6 |
Binocular |
Telemed 3×; working distance |
Telemed 3×; working distance |
0.22 |
1.22 |
10 |
1.3 |
1.3 |
Binocular |
Telemed 4×; working distance |
Telemed 4×; working distance |
1.0 |
1.0 |
11 |
1.0 |
1.0 |
Binocular |
Telemed 4×; working distance |
Telemed 4×; working distance |
0.3 |
0.4 |
12 |
1.3 |
1.1 |
Binocular |
Telemed 4×; working distance |
Telemed 4×; working distance |
1.1 |
0.5 |
13 |
1.6 |
2.5 |
Monocular |
2.5×; working distance infinity; visual field |
- |
1.22 |
- |
14 |
|
1.3 |
Monocular |
- |
6×; visual field |
- |
1.1 |
15 |
1.3 |
1.22 |
Binocular |
Telemed 4×; working distance |
Telemed 4×; working distance |
0.92 |
1.0 |
OD: Right eye; OS: Left eye; VA: Visual acuity; BCVA:
Best corrected visual acuity; logMAR: Logarithm of minimum angle of resolution;
PL: Perception of light.
Near vision aids prescription were: binocular high
plus near reading addition glasses in four patients (26.7%), stand magnifiers
in three patients (20.0%), video magnifiers in seven patients (46.7%).
Binocular glass mounted telescope for near was prescribed for one patient
(6.7%).
Marked improvement in near vision noticed in all
patients. The near visual acuities (logMAR) after near LVAs were ranged from
0.1 to 0.8; the mean near visual acuity was 0.23±0.24. The impact of near
vision aids on the near visual acuity was as per the following: 11 patients
(73.3%) achieved aided near visual acuity of 0.1, one patient each (6.7%)
accomplished aided near visual acuity of 0.4, 0.5, 0.8 and 0.7 respectively.
The average number of lines gained by the patients was 10.26±2.68 (range:
5.0-15.0; Table 2). Following the use of LVAs, visual acuity of the better eye
was equal to or better than 0.3 logMAR was achieved in 40% of patients for far
vision and 73.3 % of patients for near vision (Table 2).
Table 2 Types and specifications of LVAs used for
near vision, the BCVA and the reading speed before and after their use
Patient No. |
Near BCVA before use of LVAs |
LVAs |
Use of LVAs for near |
Magnification (diopter) |
Near BCVA after use of near LVAs |
|
|||
OD |
OS |
OD |
OS |
OD |
OS |
||||
1 |
1.0 |
1.0 |
20-40 wpm |
Monocular |
+5 (glasses) |
+5 (glasses) |
0.1 |
0.1 |
>60 wpm |
2 |
0.6 |
- |
20-40 wpm |
Monocular |
+4 (monocular glasses) |
- |
0.1 |
- |
>60 wpm |
3 |
1.3 |
- |
Cannot read school books without aid |
Monocular |
5× (20 D) stand magnifier (dimensions |
- |
0.1 |
- |
40-60 wpm |
4 |
>1.6 |
- |
Cannot read school books without aid |
Binocular |
Video magnifier, up to 12×174×90.3× |
- |
0.8 |
- |
20-40 wpm |
5 |
1 |
0.9 |
<20 wpm |
Monocular |
+10 (binocular glasses) (12 D prism base in) |
+10 (binocular glasses, 12 D prism base in) |
0.1 |
0.1 |
40-60 wpm |
6 |
>1.6 |
- |
Cannot read school books without aid |
Binocular |
Video magnifier pocket viewer |
- |
0.7 |
- |
40-60 wpm |
7 |
>1.6 |
>1.6 |
Cannot read school books
without aid |
Binocular |
Illuminated stand magnifier 10× (38 D), dimension of lens |
|
0.4 |
0.4 |
40-60 wpm |
8 |
1.6 |
- |
Cannot read school books without aid |
Monocular |
Video magnifier pocket viewer |
- |
0.5 |
- |
>60 wpm |
9 |
1.0 |
1.6 |
<20 wpm |
Binocular |
Rido Med (binocular glass mounted telescope for near) 2.5× distance 350
visual field 75/ |
|
0.1 |
0.6 |
40-60 wpm |
10 |
1.3 |
1.3, bad contrast |
Cannot read school books without aid |
Binocular |
Video magnifier pocket viewer |
|
0.1 |
0.1 |
>60 wpm |
11 |
0.8 |
0.8 |
20-40 wpm |
Binocular |
Labo clip 3× (7.75 D) over distance correction, distance |
|
0.1 |
0.1 |
>60 wpm |
12 |
1.4 |
1.1 |
<20 wpm |
Binocular |
Stand magnifier 6× (24 D) |
|
0.1 |
0.1 |
>60 wpm |
13 |
1.3 bad contrast |
- |
Cannot read school books without aid |
Monocular |
Video magnifier pocket viewer |
- |
0.1 |
- |
40-60 wpm |
14 |
- |
1.6 |
Cannot read school books without aid |
Monocular |
- |
Video magnifier pocket viewer |
- |
0.1 |
40-60 wpm |
15 |
1.6 |
1.5 |
Cannot read school books without aid |
Binocular |
Video magnifier pocket viewer |
- |
0.1 |
0.1 |
40-60 wpm |
OD: Right eye; OS: Left eye; VA: Visual acuity; BCVA:
Best corrected visual acuity; logMAR: Logarithm of minimum angle of resolution;
wpm: Word number read per minute; LCD: Liquid crystal display.
Reading speed before using the near visual aids was
<20 wpm in three patients (20%), 20-40 wpm in three patients (20%), nine
patients cannot read at all without LVA (60%). With using of near visual aids
reading speed improved in all patients showing reading 20-40 wpm in one patient
(6.7%), 40-60 wpm in nine patients (60%) and >60 wpm in five patients
(33.3%). Table 2 demonstrated the types and effects of use of LVAs on
near vision enhancement.
A statistically significant improvement was found in
far and near visual acuities after low vision aids prescription compared to
visual acuities at presentation (P<0.01). Concentric contraction of
the peripheral field up to 20 degrees with no involvement of the central field
was detected in 6 patients (40%) and one patient (6.7%) had complete homonymous
hemianopia. It was difficult to perform it in the rest of the patients because
of poor vision and uncooperative children.
The response to the LVPrasad-FVQ pre- and post-LVAs
was summarized in Table 3. The most frequently affected visual tasks were those
related to near vision and hence affect their education. As a response to
question number 20; preceding the utilization of the aids, 73.3% of children
expressed that their vision was much worse than their companions’ vision; the
rest expressed that it was a little worse than their companions. After use of
aids, 53.3% expressed that their vision as good as their companions and 46.7%
expressed that it was a little worse than their companions. The variance in
functional vision pre- and post-LVAs was statistically significant with all
activities (P<0.05).
Table 3 Number
and percentage of patients responding to each question with the degrees of
difficulty of performing the visual tasks in the
No. |
Questions |
Pre-LVAs scores, n (%) |
Post-LVAs scores, n (%) |
P |
||||||
2 |
3 |
4 |
9 |
2 |
3 |
4 |
9 |
|||
16 |
Do have difficulty in locating a ball while playing
in the day light? |
|
7 (46.7) |
8 (53.3) |
|
|
8 (53.3) |
7 (46.7) |
|
0.001 |
19 |
Do you difficulty in identifying colors (e.g.
while colorings)? |
4 (26.7) |
5 (33.3) |
6 (40.0) |
|
7 (46.7) |
5 (33.3) |
3 (20.0) |
|
0.02 |
5 |
Do you have any difficulty in copying from the
blackboard while sitting on the first bench in your class? |
|
0 |
15 (100) |
|
2 (13.3) |
4 (26.7) |
9 (60.0) |
|
0.03 |
10 |
Do you have any difficulty in finding the next line
while reading when you take a break and then resume reading? |
|
0 |
15 (100) |
|
|
7 (46.7) |
8 (33.3) |
|
0.47 |
11 |
Do you have any difficulty in locating dropped
objects (pen, pencil and eraser) within the classroom? |
|
6 (40.0) |
9 (60.0) |
|
|
7 (46.7) |
8 (53.3) |
|
0.001 |
1 |
Do you have any difficulty in making out whether
the person you are seeing across the road is a boy or a girl, during the day? |
|
7 (46.7) |
8 (53.3) |
|
|
9 (60.0) |
6 (40.0) |
|
0.007 |
7 |
Do you have any difficulty in reading the other
details on the bus (such as its destination? |
|
3 (20.0) |
12 (80.0) |
|
|
6 (40.0) |
9 (60.0) |
|
0.04 |
8 |
Do you have any difficulty in reading your
textbooks at an arm’s length? |
|
0 |
15 (100) |
|
|
7 (46.7) |
8 (53.3) |
|
0.47 |
2 |
Do you have any difficulty in seeing whether
somebody is calling you by waving his or her hand from across the road? |
|
3 (20.0) |
12 (80.0) |
|
4 (26.7) |
5 (33.3) |
6 (40.0) |
|
0.006 |
12 |
Do you have any difficulty in threading a needle? |
|
|
1 (0.7) |
14 (93.7) |
|
|
3 (20.3) |
12 (80.0) |
0.2 |
4 |
Do you have any difficulty in walking home at night
(from tuition or a friend’s house) without assistance when there are
streetlights? |
|
0 |
15 (100) |
|
|
7 (46.7) |
8 (53.3) |
|
0.47 |
9 |
Do you have any difficulty in writing along a
straight line? |
|
0 |
15 (100) |
|
9 (60.0) |
5 (33.3) |
1 (6.7) |
|
0.45 |
17 |
Do you have difficulty in applying paste on your
tooth brush? |
|
5 (33.3) |
10 (66.7) |
|
|
8 (53.3) |
7 (46.7) |
|
0.04 |
14 |
Do you have difficulty in climbing up or down
stairs? |
|
3 (40.0) |
12 (60.0) |
|
|
5 (53.3) |
10 (46.7) |
|
0.02 |
15 |
Do you have difficulty in lacing your shoes? |
|
5 (33.3) |
10 (66.7) |
|
|
9 (60.0) |
6 (40.0) |
|
0.002 |
18 |
Do you have difficulty in locating food on your
plate while eating? |
|
6 (40.0) |
9 (60.0) |
|
|
10 (66.7) |
5 (33.3) |
|
0.04 |
6 |
Do you have difficulty in reading the bus numbers? |
|
3 (20.0) |
12 (80.0) |
|
|
6 (40.0) |
9 (60.0) |
|
0.04 |
3 |
Do you have difficulty in walking alone in the
corridor at school without bumping into objects or people? |
|
6 (40.0) |
9 (60.0) |
|
|
9 (60.0) |
6 (40.0) |
|
0.03 |
20 |
How do you think your vision is compared with that
of your normal‑sighted friend? Do you think your vision is: |
0.03 |
||||||||
As good as your friend’s (0) |
0 |
0 |
||||||||
A little bit worse than your friend’s (1) |
4 (26.7) |
7 (46.7) |
||||||||
Much worse than your friend’s (2) |
11 (73.3) |
8 (53.3) |
||||||||
13 |
How much difficulty do you have indistinguishing
between 1 rupee and 2 rupee coins (without touching)? |
|
6 (40.0) |
9 (60.0) |
|
|
9 (60.0) |
6 (40.0) |
|
0.03 |
The questionnaire was based on four parameters: distance
vision (No.1-2, 4-7), near vision (No.8-10, 12-13, 15), color vision (No.17,
19), field of vision (No.3, 11, 14, 16, 18). Responses for each item rated on a
5-point Likert scale: 0=no difficulty, 1=little difficulty, 2=some difficulty,
3=great difficulty, 4=unable to perform the task due to visual reasons, 9=not
applicable. LVAs: Low vision aids.
DISCUSSION
Low
vision patients’ prevalence is expanding as future increments. In
In our study, visual acuity improvement in children
with low vision following the use of LVAs was documented in all patients.
Improvement was demonstrated as increase in visual acuity by a least one line
on the chart used either for distance or near, improvement of reading speed,
and improvement of quality of life documented by questionnaire. Gothwal et
al[10] have reported that children in
correlation to grownups have a very high rate of successful low vision aids
utilize, provided that aids are properly prescribed. To our knowledge, no
previous studies published about management of visual impairment using LVAs
following successful treatment of pediatric CNS tumors. Telescopic systems
either monocular or binocular, were utilized to enhance distant vision. Low
magnification telescopes are preferred by children due to their simplicity of
manipulation and their larger field of view.
In
the present study, 12 patients (80.0%) had far visual acuity of equal or better
than 1.3 (logMAR) in the best seeing eye after use of LVAs. Utilization of
telescopic systems by visually disabled school children ought to be promoted
according to Haddad et al[11], even for school
activities. Patients who accomplished visual acuity better than 20/400=(1.3
logMAR) will get a better opportunity of success with the utilization of
optical aids[12]. That was evident in the present study as telescopic systems for far vision
were prescribed and successfully used by children. Scanning eye movement is a
part of adaptation for visual field enhancement was one of the main items of
our training sessions. A patient with a 10 degrees static visual field can get
a functional dynamic visual field of more than 50 degrees using scanning eye
movements[13].
Near vision low vision aids were prescribed for all
patients: the most frequently used aid in the present study was video magnifier
(pocket viewer) in 46.7% due to its high magnification, better resolution,
freedom to change head position, domination of contrast polarity and its
suitability for patients with peripheral field defects. Two patients (13.3%)
stopped using stand magnifiers as near aids towards the end of follow up period
due to limited field of view. The ordinary conventional aids are widespread
because they are usually inexpensive, portable, and versatile and gives
appropriate magnification in mild or moderate visual impediment however
electronic devices despite their advantages were administrated less frequently
because they were excessively costly, their standby times were to some degree
short and they were hard to repair if harmed[14].
Omar et al[15] recorded in their study
that the most preferred near low vision devices were hand held magnifiers with
percentage 54.2% of cases. Yet, another studies reported that stand magnifiers
were the most frequently utilized. Haddad et al[11]
reported that 2.8×
Most of the patients in the present study reported
their troubles with near and distance vision to be of equivalent significance
as detected by their responses to the questionnaire with significant reduction
across all domains in children. Those children had previous experience with
normal visual performance since birth until the development of CNS tumors and
their late effects on vision compared to those who had congenital visual
disabilities dating since birth, they did not have a basis for correlation to
mild, moderate or great difficulty since they usually perform the errand in one
specific way. This was in agreement with Gothwal et al[10].
Statistical significant improvement of visual tasks
regarding the parameters of far vision, color vision and field of vision was
based on self-reporting of the functional abilities of visually impaired
children using the validated (LV Prasade-FVQ) questionnaire, practitioner’s
evaluation of children activities by observation during the follow up visits in
the clinic and also by the feedback from parents and teachers about daily and
academic activities in this study.
In conclusion, LVAs rehabilitation was a
markedly effective method of improving functional vision in children with
visual impediment secondary to CNS tumors, provided that appropriate LVAs are
prescribed according to their needs and visual rehabilitation accomplished.
ACKNOWLEDGEMENTS
The authors thank all the children involved in the
study and their families, also thank Dr. Azza Mohamed Ahmed Said, Assistant
Professor of Ophthalmology for her precious aid in statistical analysis work.
Conflicts of Interest: Zaki RG, None; Elshinawy RF, None; Naguib KM, None.
REFERENCES