Bioptic telescopes - The College of Optometrists

Optometry in Practice 2013 Volume 14 Issue 1 11 – 20
Bioptic telescopes
Moyra E McClure1,2 BSc MCOptom MPhil PgCUT
1
School of Biomedical Sciences, University of Ulster, Coleraine
Low Vision Clinic, Shankill Wellbeing and Treatment Centre, Belfast
2
EV-10778 C-30174
1 CET point for UK optometrists
Introduction
A bioptic telescope comprises a miniature telescope that is
mounted within a spectacle lens, positioned superiorly to the
user’s visual axis and angled upwards (Figure 1). Classifying
a bioptic telescope as an optical low-vision device, design
features would indicate that it is most suitable for those
with a mild to moderate visual impairment. The user
habitually views through the ‘carrier’ spectacle lens for
distance visual acuity. By lowering the chin and holding
the gaze in the primary position, the user employs the
bioptic telescope to view a magnified image of a specific
target. The movement between the non-magnified and
magnified image is termed ‘translation’.
In individuals with central visual impairment, visual function
measures depict decline or loss of resolution, contrast
sensitivity, central visual fields, colour vision and light and
dark adaptation. Consequential visual disabilities experienced
for distance and intermediate tasks include the reduced
ability to read signage, detect facial features and expressions,
enjoy television, use a computer, appreciate scenery or view
detail in a theatre, sports event or art/museum exhibition.
By demonstrating a bioptic telescope, the low-vision clinician
can offer an aid that provides a magnified distance image,
thereby improving resolution and reducing associated
visual disabilities. Differing from hand-held monocular
or binocular telescopes, a bioptic telescope provides a
spectacle-mounted hands-free method for magnification at
a distance that can be used while walking around. Utilising
a bioptic telescope can, for example, provide significant
improvement to the ability to read transport signage, such
as an airport direction board, and thus enhance independent
travel in those with a central visual impairment.
Use of a bioptic telescope is not prescriptive, in that all
individuals will have different low-vision goals. Tasks for
which a bioptic telescope has been used include those for
distance, intermediate and near (Table 1). Field-of-view
restrictions compromise near use and thus a bioptic telescope
is usually prescribed as a mobility aid.
Guidance on selecting the suitable
candidate to refer for a trial with a
bioptic telescope
Identifying the person with a visual impairment who would
be suitable for a bioptic telescope is paramount for the
optometrist, low-vision clinician, rehabilitation worker,
peripatetic teacher, higher education disability services
adviser and other service providers involved in low-vision
care. This general guidance can enhance the selection of a
suitable candidate and assist to eliminate those for whom a
bioptic telescope will definitively not be beneficial.
Figure 1 (a) A bioptic telescope user who currently
uses the Ocutech VES-Autofocus, viewing through the
‘carrier’ spectacle lens. (b) The user viewing through the
bioptic telescope.
Age is not a barrier to using a bioptic telescope, with those
from age 8 to over 90 years using the device (Allen 2009).
Date of acceptance: 2 November 2012. Address for correspondence: ME McClure, School of Biomedical Sciences, University of Ulster, Cromore Road,
Coleraine BT52 1SA. [email protected].
© 2013 The College of Optometrists
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M E McClure
Distance visual acuity between 6/18 and 6/75 is clinically
viewed as optimum for success with a bioptic telescope.
However, those whose acuities are slightly better, for
example, 6/15, should not be excluded if other factors indicate
possible ability to use the device. Similarly, those patients
with visual acuity up to 6/120 may be suitable candidates
(Ocutech Inc. 2011).
Table 1. The range of tasks that could be performed
with a bioptic telescope
Distance of task
Task for which a bioptic telescope
may be utilised
Distance
Improving ability to see signage:
transport notices, stationary bus
numbers, train platform numbers,
airport notice boards
Enhancing the ability to see in an
educational environment: lectures,
classroom whiteboard, wall charts,
clocks and signs
Appreciating detail at the theatre
Seeing a score board at a
sporting event
Seeing scenery and sight-seeing detail
on holiday
Seeing detail for hobbies, even horse
riding, cycling or playing bowls
Driving in the Netherlands and in
those states of the USA issuing a
licence for use with a bioptic telescope
Intermediate/near
Watching television
Seeing sheet music
Seeing to use a computer
Improving ability in a social setting by
seeing facial features and expression
Improving ability to see food shopping
expiry dates, prices and clothes sizes
Enhancing detail at an art or
museum exhibition
Playing cards or board games
Selecting a bioptic telescope user can be assisted by
considering those with an ocular condition that causes
a reduction in visual acuity. Those with peripheral visual
field loss will not benefit from a telescope as it will further
restrict the visual field. Matching bioptic telescope use
with those with macular disorders, namely age-related
macular degeneration or macular dystrophy, is a key to
success. The following studies demonstrate the extensive
numbers of these individuals and thus a readily available
patient base. Degeneration of the macula and posterior pole
accounts for the majority of certifications as ‘sight-impaired’
(58.6%) or ‘severely sight-impaired’ (57.2%) in the UK
(Bunce et al. 2010). Patients with age-related macular
degeneration provide the bulk of attendees at low-vision
clinics and of visual impairment in population studies
(Lindsay et al. 2004; Williams et al. 2007).
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Reduced visual acuity in children and teenagers may be
caused by congenital or hereditary ocular conditions that
include albinism, nystagmus, congenital cataract, retinopathy
of prematurity, macular dystrophies and, more rarely,
achromatopsia and choroideraemia. Bioptic telescope use
is possible for those who have any one or more of these
ocular disorders.
Psychological adjustment to the onset of visual impairment
mimics the grieving process as the individual can experience
emotions of anger, depression and disbelief before
‘acceptance’. ‘Acceptance’ means realisation of the sight loss,
with an attitude of employing available services and aids,
whilst still evidently preferring to have full eyesight. Bioptic
telescope use is more likely to be successful in those at this
last psychological stage. There may, however, be some
individuals who would benefit from the enhanced visual
acuity provided by a bioptic telescope even though they are
still coping with the psychological impact of sight loss.
Confidence with a bioptic telescope can be determined by
the individual with low vision. If potential users are
unconcerned at the cosmetic appearance of a bioptic
telescope, they are likely to accept the device. By explaining
to interested patients that the device is evident and will
make them obvious in public, the individual has reasonable
expectations at the trial.
Prices of bioptic telescopes can range from approximately
£600 to £2000. As it is not funded through the National
Health Service, cost may be a factor. Bioptic prescribers can
provide possible charitable sources of funding for the device.
Prior successful experience of a hand-held telescope is likely
to enhance success. Telescopes are usually prescribed at
review appointments in a low-vision clinic because near
tasks are initially addressed. Using a telescope is more
complex than using a near aid and prescribing rates for
telescopes are considerably lower. Lowe and Rubinstein (2000)
found a telescope dispensing rate of 5.3% in a low-vision
clinic over 9 years. Telescope prescribing rates for the
Welsh low-vision scheme were approximately 15% (Court
et al. 2011). Potential bioptic telescope users should ideally
be loaned a hand-held telescope from a low-vision clinic and
monitored for good handling and usage prior to a referral.
Some patients struggle with the manual dexterity of a
hand-held telescope and may demonstrate a better
performance with a bioptic telescope due to its position
in the spectacles.
On receiving a referral for a bioptic trial, the bioptic
prescriber sends a brochure and price list. By following up
with a telephone call to discuss a bioptic telescope, the
patient can make a more informed choice as to whether
to proceed with a trial and the prescriber can discuss any
specific low-vision goals. In this way, further refinement for
suitability is achieved.
Low-vision clinics are likely to provide the majority of
referrals. Other sources may include ophthalmologists,
optometrists in practice and community rehabilitation
Bioptic telescopes
workers. Significant numbers of self-referrals can be received
and, while this demonstrates a patient interest and probable
acceptance of the device, it can be helpful for bioptic
prescribers to discuss diagnosis, low-vision care, use of optical
aids and habitual vision prior to a trial.
Bioptic telescope prescribers are likely to be enthusiastic
low-vision clinicians and wish to encourage public awareness
of their unique service. By engaging with local low-vision
clinic staff and rehabilitation workers as well as speaking
at community events for those with sight loss about bioptic
telescopes, more referrals can be generated.
Accessing bioptic telescopes in the UK
For those with a visual impairment in the UK, geographical
access to trial of a bioptic telescope vastly improved from
2007 with the introduction of ‘bioptic partners’ associated
with Optima Low Vision Services Ltd. Optometrists and
dispensing opticians specialising in low vision were trained
in prescribing bioptic telescopes and on purchasing a trial
kit of bioptic telescopes now offer trial and dispensing
by appointment (Optima Low Vision Services Ltd 2009).
Although patients have to travel, the distance has been
significantly reduced. Bioptic partners provide this service
privately, charging a trial fee and recommended retail price
for the bioptic telescope.
Allen (2009) reported fitting 130 users in the UK, the
majority of whom were aged in their 70s and had
age-related macular degeneration. Magnifications of ×2.2
to ×6 were employed, with the most commonly prescribed
being ×4. Future studies of bioptic users are likely to show
some increase in numbers, in line with the increase in those
with a visual impairment in the ageing population and the
improved access to the service.
History of bioptic telescope development
Dr W. Feinbloom is credited as the founder of the Bioptic
System when, in 1958, he mounted a small Galilean telescope
within a spectacle lens in order that visual function may
be improved in those with a visual impairment. Previous
literature, in 1917 and 1953, depicting bioptic telescope
designs in Germany provided no evidence of success.
Literature reviews provide evidence for basic bioptic
telescopic designs. Bergenske and Raasch (1982) applied
optical blocking tape (circular strong double-sided tape) to a
×3 astronomical monocular telescope to front mount it on
to spectacles. The 41-year-old user, with diabetic retinopathy,
was delighted to continue his music between 50 and 90 cm.
Although the device was further from the eye due to the
mounting as compared to that within a lens, the user did
not complain of a restricted field of view. Jose and Browning
(1983) fitted a bioptic telescope into the spectacles of a
contact lens/spectacle telescope of a user with congenital
cataract. The contact lens/spectacle telescope comprised
a –16.50DS contact lens and an objective spectacle lens of
+20.00DS, giving ×1.45 with a 15mm vertex distance and
visual acuity 6/24. The addition of a ×2.2 bioptic telescope
increased the total magnification to ×3 and visual acuity
to 6/12. While these early enterprises provide interest,
bioptic telescopes are primarily associated with Designs for
Vision Inc. and Ocutech Inc.
Designs for Vision Inc. was started by Dr Feinbloom in 1961,
to produce his designs of bioptic systems, many of which
are still in use today. Ocutech Inc. was established in 1984
to produce a range of astronomical bioptic telescopes with
a novel design feature of the optics located within a
horizontal unit, placed perpendicular to the line of sight.
These were developed and patented as the Visual
Enhancement System (VES) by Dr J Pekar and Dr HA Greene,
using grant support from the National Eye Institute and
the Ontario Canadian Ministry of Health. Pioneering
within the bioptic systems was the first autofocus bioptic
telescope, produced in 1996 by Ocutech (Figure 1). Using
×4 magnification, the astronomical telescope is housed
in a horizontal unit in keeping with the VES designs and
weighs 71g. It has the ability to autofocus from infinity to
30cm by the use of an infrared ranging system. The
VES-Autofocus can refocus to provide a clear image in less
than a second and is powered by a separate rechargeable
battery providing 8 hours’ use (Greene et al. 1992, 2001).
The Ocutech autofocus design is currently being upgraded.
In 1989, a ‘behind the lens’ astronomical bioptic telescope,
mounted temporally or inferior temporally, was designed
to improve cosmetic appearance. Lateral eye movements of
36° were required for utilisation. Clinical trial in 20 subjects
demonstrated this eye movement could be maintained
for a maximum of 15 minutes before discomfort. No head
movement was required, clip-on glare filters could be
applied and social interaction could be improved. With
previously designed bioptic telescopes, users point the
device at the person they are talking to, resulting in loss of
eye contact and sometimes feelings of intimidation as the
telescope objective is pointed at the face. The ‘behind the
lens’ telescope is not directed at the face of the individual
with whom the user is having a dialogue, as the user flicks
the eye to use the device (Spitzberg et al. 1989).
Significantly less noticeable than all previous bioptic
telescopes, the protocol for an ‘in the lens’ bioptic
telescope shows enhanced cosmetic appearance and
the ability to provide the user with a magnified and
non-magnified image simultaneously. Bioptic prescribers
eagerly await the manufacture of this novel design (Peli and
Vargas-Martin 2008).
Types of bioptic telescopes currently
available in the UK
Both Ocutech VES and Designs for Vision bioptic telescopes
are available in the UK (Table 2). Ocutech VES have an
eyepiece that focuses from +12 to –12D. A refractive error
over 3DC should be glazed within the eyepiece. Available in
×3, ×4 and ×6 magnification, the monocular VES-K is easily
operated and weighs just 25.5g (Figure 2). The monocular
VES-Sport is available in ×4 and ×6 and also weighs 25.5g.
Aiming at improving cosmetic appearance, the VES-Sport
is available in casing colours of black, blue, red, pink, silver
and green (Figure 3). Within this telescope, a parallax
adjustment control allows for the device to be aligned for
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M E McClure
optimal viewing at distance or intermediate. By moving a
small screw on the VES-Sport housing, the telescope is
optically aligned for each individual user. The factory setting
for the VES-Sport is for users whose tasks are mostly
distance and the parallax is thus set for distance. For those
users whose tasks are mostly intermediate, for example,
viewing music, the parallax control should be altered by the
prescriber to the intermediate setting. This is a very
small rotation of only 5° and the alteration should not be
undertaken by the user. Providing ×3 magnification in
monocular or binocular form, the VES-Mini may be centred
for distance or near, is a round telescope, offers the widest
field of view and is the lightest of the VES at 17g.
a bridge mounting system that is adjustable for right or left
eyes in the demonstration kit. The VES-Mini telescope is
also fixed by the ‘through the lens’ design. To reduce glare,
a sun filter is available for all systems in a range of colours
(Ocutech Inc. 2011). This can be placed behind the carrier
spectacle lens and positioned to clip on to the back of the
frame. To provide further glare protection through the
eyepiece, either a cap with a filter or an internal filter
is available.
Figure 2. Ocutech VES-K.
All of the Ocutech VES have the eyepiece positioned
‘through the lens’ for proximity to the eye. The carrier
spectacle lens thus has a drilled circular aperture. The
bioptic telescope is inclined superiorly at an angle of 12°
that provides for enhanced use in the primary position of
gaze on dropping the chin. The VES horizontal units, namely
the VES-K and the VES-Sport, are attached to the frame by
Figure 3. Ocutech VES-Sport with colour samples of
the housing.
Table 2. The range of bioptic telescopes currently available in the UK
Manufacturer
Bioptic telescope
name
Focusing method
Magnification
Near focusing point
Field of view
at infinity
Ocutech
VES-K
Manual focus
×3
×4
×6
18cm
23cm
30.5cm
12.5°
12.5°
9.6°
Ocutech
VES-Sport
Manual focus
×4
×6
23cm
30.5cm
12.5°
9.6°
Ocutech
VES-Mini
Manual focus
×3
18cm
15°
Designs for Vision
Standard
Fixed focus
×2.2
Distance viewing only
12°
Near lens cap
Designs for Vision
Wide angle
Fixed focus
×2.2
Distance viewing only
16°
Near lens cap
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Designs for Vision
Standard
Manual focus
×3
18cm
8°
Designs for Vision
Standard
Manual focus
×4
23cm
6°
Bioptic telescopes
Providing bioptic telescopes for monocular or binocular
viewing, bioptic telescopes by Designs for Vision have a
Galilean design and set or manual focus. All of these use
a ‘through the lens’ system for the eyepiece. Whilst their
standard bioptic telescopes are available in magnifications
×1.7, ×2.2, ×3 and ×4, a range of wide-angle ones are
offered in ×1.4, ×1.7, ×2.2 and ×3 magnification. Within the
UK, the ×2.2, ×3 and ×4 magnification standard and the
×2.2 wide-angle bioptic telescopes are available (Figure 4).
The ×3 and ×4 magnification are round telescopes and the
×2.2 standard and wide-angle have a rectangular objective
lens. All are made from glass lenses in a plastic casing. The
telescope is angled 10° upwards and the optical centre of
the bioptic telescope is placed 10mm below the top of the
carrier lens. For optimum visual acuity with the telescope,
it is recommended that the refractive error of the user is
incorporated within the eyepiece of the telescope. The
spectacle prescription will also be used in the carrier lens.
Bifocals may be dispensed within the carrier lens, providing
that there is a 10mm distance between the inferior rim of
the telescope and the top of the bifocal segment.
Alternatively, a near-vision telescope can be constructed by
the addition of a lens cap. Using the dominant eye for the
near-vision telescope provides monocular reading as the
telescope is not at the near interpupillary distance (Designs
for Vision Inc. 2012).
Figure 4. Designs for Vision ×2.2 rectangular
wide-angle bioptic telescope set in the demonstration
spectacle frame showing the ‘through the lens’
placement of the bioptic telescope.
Factors affecting the prescribing of a
bioptic telescope
When the patient attends for a trial, a thorough history
and symptoms and assessment of daily living tasks are
performed. Good general health, stable ocular conditions
such as albinism, and independence show suitability for
prescribing. Successful bioptic telescope candidates are those
who often know their goal for which the device will be used.
By assessing visual functions of distance and near visual
acuity, comparisons of improvement can be made with a
hand-held monocular telescope and a bioptic telescope.
Moderate loss of contrast sensitivity, namely equal to or
worse than 1.05 log units on the Pelli–Robson chart,
will detract from bioptic telescope success and thus,
measurement of this visual function is vital. Those with
lower contrast ability may be better suited to a Galilean
design because there are fewer optical components in the
system and thus less loss of contrast when viewing through
the telescope. Bioptic telescopes are prescribed to the
better-seeing dominant eye.
Prescribers will habitually seek at least a three-line
improvement on a logMAR chart for effective bioptic
telescope use, equating to a doubling of the visual angle.
While improvements of six logMAR lines have been shown
in users, demonstrating improvement in functional ability
indoors and outdoors is of more significance to the patient
(Allen 2009). For this reason, the testing room is not the
ideal location and the user needs to try tasks such as seeing
signs, using a computer, reading music, seeing faces, viewing
pictures and seeing shop prices and sell-by dates. A bioptic
prescriber needs to be flexible and free to undertake a
‘walkabout’ with the patient. The prescriber will habitually
examine the patient’s ability to translate and manipulate
the manual focus efficiently. Assessment will be made of
the patient’s ability to cope with the narrow field of view, by
learning to scan the object of regard.
Binocular versus monocular prescribing of the bioptic
telescope depends on a range of factors. Peli (2001) names
the use of a monocular telescope as ‘bi-ocular multiplexing’
when users have useful acuities in both eyes, as they view a
magnified and non-magnified image. A bioptic telescope
provides magnification in such a way that the visual
system can adapt to the altered image and field of view
produced. Essentially, a bioptic telescope provides a
magnified image that reduces the ability to see the overall
field of view. Where a ×4 magnification is employed, a 10°
field through the telescope employs 40° of the retina and
thus a ring scotoma of 15° effectively blocks peripheral
vision (Peli 2001). Where this system is dispensed
monocularly, the eye without the telescope provides the
full field of view and the visual system more easily adapts to
two images. In the majority of cases, therefore, monocular
prescribing of bioptic telescopes is undertaken to enhance
visual multiplexing and provide a safety feature for mobility.
Monocular bioptic telescope use is the only option in some
cases, such as the range of Ocutech VES, excluding the
VES-Mini. Both the Ocutech VES-Mini and the Designs for
Vision bioptic telescopes are usually supplied monocularly
but can be dispensed binocularly.
The clinician prescribing a bioptic telescope will also
examine the impact of factors which would be considered
when referring a patient for trial. Outgoing personality
type can positively influence whether the patient proceeds
to purchase a bioptic telescope, in the same way as it can
influence motivation to use a distance telescope (Lowe
and Rubinstein 2000). ‘Hard’ signs for successful prescribing
were proposed by Greene et al. (2001), who stated that
the habitual visual acuity is between 6/21 and 6/60
improving to at least 6/15 with the device, contrast sensitivity
is good and the better eye is the dominant eye. Greene
et al. (2001) quantified contrast sensitivity by the ability
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M E McClure
to distinguish facial features through the telescope at 3m, a
real-world task that requires a good level of contrast ability.
Thus, using the Pelli–Robson chart, those with contrast
sensitivity of 1.20 logunits or better, exhibiting a mild loss
of contrast ability, are likely to be better astronomical
bioptic candidates than those with moderate loss of
contrast sensitivity of 0.60–1.05 logunits. Those excluded
from bioptic usage are those with a severe loss of contrast
sensitivity, noted as 0–0.45 logunits on the Pelli–Robson
chart, as they are unlikely to benefit from optical appliances.
‘Soft’ signs indicating prescribing comprise the low-vision
goal being at a distance of intermediate or beyond and the
patient being excited about the device and manually able
to manipulate it (Greene et al. 2001). The final decision is
obviously determined by the patient.
Spectacle frames dispensed with the bioptic telescope are
often from a small carefully selected range, such as the
Ocutech frame, where the double bridge is necessary for the
fitting of the device. Where a bioptic telescope is positioned
through the lens, the optometrist or dispensing optician
may supply a spectacle frame. It is advisable that the frame
selected is metal with adjustable nose pads and spring joints.
Carrier spectacle lenses can be single-vision, bifocal or
varifocal and clear, tinted or photochromic, and hi-index.
For those who use the device indoors and outdoors and
experience significant disability glare, photochromic is a
good option. Polycarbonate is not recommended.
On collection of the bioptic telescope, the frame is fitted,
visual functions are reassessed with the device and advice
is given on use. For the Ocutech VES-Autofocus, a training
CD-ROM is supplied. While formal programmes of bioptic
telescope training are in place for driving in the USA, no
standardised training is provided in the UK other than
that provided at the collection appointment. Evidently,
significant clinical time is required for the trial, dispensing
and collection of the device. However, with evidence
pointing to an improved bioptic telescope ability following
training (Szlyk et al. 2000), successful use of the device
may be enhanced by further instruction. Liaisons with
rehabilitation services and/or charitable bodies involved
in mobility training would be beneficial to undertake this
instruction and/or be involved in the initial trial.
Although it is not advisable to use the device in the rain,
users have employed a baseball cap to shield the device
from light rain. In addition, this reduces disability glare and
can help to disguise the device from the public.
Because of the unusual appearance of a bioptic telescope,
the clinician should reduce the risk of peers’ comments
when prescribing to a child by explaining the device to fellow
school pupils (Kelleher 1974). This may involve a visit to the
child’s classroom or collaboration with a peripatetic teacher.
Driving with a bioptic telescope
Controversial as it is, driving with a bioptic telescope is
currently permitted in 39 states of the USA and in the
Netherlands (Luo and Peli 2011). In 1971, Dennis Kelleher
16
was the first individual to be issued with a driver’s
licence using a bioptic telescope, by the state of California
(Kelleher 1976). Prior to licensing, Korb (1970) had reported
on the use of bioptic telescopes for driving following
extensive training and subsequently, in the 1970s, the
Massachusetts driving authority licensed 26 of his bioptic
telescope users. Feinbloom (1977) experienced his first
bioptic telescope driver when one of his patients
self-initiated driving with his ×2.2 bioptic telescope that
had improved acuity from 6/30 to 6/9. Of 300 subsequent
bioptic telescopes fitted for driving, Feinbloom noted that
the majority, 53%, were younger than 40 years, and had
previously driven. The lowest visual acuity was 6/60 and
no serious accidents to a person or car occurred. The merits
of bioptic telescope driving are the enhancement of
independence and employability for those of moderate
visual impairment. Bioptic telescope driving may be of more
benefit to those negotiating unfamiliar routes as it enhances
resolution and the ability to read road signs (Bailey 1995).
Concerns over safety of driving with a bioptic telescope
have been addressed by licence restrictions, a compulsory
bioptic telescope driver training and a fitness-to-drive test
(Brilliant et al. 1999; Newman 1976). Of the states that
permit bioptic telescope driving, there are variations in the
restrictions imposed within a bioptic driving licence with
respect to visual acuity with and without the device and
visual field specifications. Some states do not permit driving
with a bioptic telescope and others will assess the case
on individual basis by the Medical Advisory Board. Driving
with low vision, without a bioptic telescope, in some of the
states of the USA is permissible with a restricted licence.
The majority of states licensing for bioptic telescope
driving require that the visual acuity with the device is 6/12
(Brilliant et al. 1999). Visual fields of 150° are recommended,
while visual acuity through the carrier lens should be
better than or equal to 6/60 (Bioptic Driving USA 2009).
Other restrictions to the licence may include specific road
usage, destination, geographic area and daylight hours
(Levin and Kelleher 1975).
Objections to bioptic telescope driving were made on the
basis of the ring scotoma, magnified blur at speed, glare
recovery and that drivers only used the device to pass
the licensing test (Barron 1991; Verezen and Jose 2004).
Recruiting drivers who used bioptic telescopes, Bowers
et al. (2005) administered a questionnaire to examine
bioptic telescope driving usage. Of the 58 subjects, aged
between 17 and 86 years, the median visual acuity was
6/30. The subjects’ ocular disorders included albinism (38%),
other congenital conditions (22%), age-related macular
degeneration (12%), macular dystrophy (12%) and other
conditions (16%). The median years of bioptic driving were
8 years while the median years of driving were 16 years.
Drivers were equally distributed between rural and urban
areas. The bioptic telescope was worn all of the time
while driving in 62% and used for a mean time of 5% of the
total driving time. Of those of working age, 85% drove to
work. Driving tasks for which the bioptic telescope was used
were mostly navigational where resolution was required,
for example, locating the correct slip road, seeing signals
and navigating detours. Drivers avoided tasks that imposed
Bioptic telescopes
difficulties, such as night driving, bright sunshine, parallel
parking and left-hand turns. Luo and Peli (2011) studied
two bioptic telescope drivers and found significantly less
bioptic telescope usage whilst driving, as assessed using
a pilot video recording system, than reported in a
questionnaire. However, both subjects had mild visual
impairment (6/12 and 6/18), were experienced bioptic
telescope drivers and were driving in a familiar environment.
Recent evidence has shown that the area of the visual
field not seen, because of the ring scotoma of a bioptic
telescope, is observed by the other eye (Doherty et al. 2011).
Studies of accident rates for bioptic telescope usage have
been inconclusive (Clarke 1996; Levin and Kelleher
1975; Owsley and McGwin 1999; Strong et al. 2008).
Factors influencing good driving ability are more likely to
be accurate dynamic than static visual acuity; that is,
detecting a moving target whilst moving, normal visual
fields and near-normal contrast sensitivity (Owsley and
McGwin 2010). While Brinig et al. (2007) oppose a licence
for bioptic telescopic use, training programmes for bioptic
driving are recommended. Some evidence exists for the
impact of training on improved visual skills while driving
(Strong et al. 2008). Instruction can cover aspects of
processing magnified and non-magnified information
quickly and coping with lighting changes (Jose et al. 1983).
Efficient translation is a skill that needs to be developed
for driving with only brief use of the bioptic telescope for
reading signs (Bailey 1995).
In 2009, the legal vision requirements for driving in the
Netherlands were revised to allow driving with a bioptic
telescope, following a project to introduce legal bioptic
driving (Koojiman et al. 2008). Restrictions to the licence
include the requirement for visual acuity of 6/12 with the
bioptic telescope and visual acuity through the carrier
lens to be better than or equal to 6/48. Driving is only
permitted in daylight unless a further assessment permits
night-time driving. Candidates must complete training and
pass a ‘fitness-to-drive’ test.
Prohibiting the use of bioptic telescopes to meet the
driving standard in the UK, the Driver and Vehicle Licensing
Agency (DVLA) advises that the use of these devices
invalidates users’ licence and insurance. The bioptic
telescope restricts the visual field and the 120° field of
view required is not achieved. Although consultations have
been made by the medical advisory panel for driving with a
visual disorder, clinical evidence and usage of bioptic driving
in other European states will be examined prior to any
legal use of bioptic telescopes for driving in the UK (Driver
and Vehicle Licensing Agency 2011). Opponents to bioptic
driving highlight the evident difference in road systems
and traffic in Europe compared to those in the USA.
Recognising that not all individuals will be able to drive with
a bioptic telescope, those promoting bioptic driving in the
UK encourage clarification on visual requirements and
driving (Bioptic Driving Network 2012). In line with the
DVLA, bioptic prescribers do not prescribe bioptic telescopes
for driving in the UK.
Clinical studies involving a
bioptic telescope
Clinical research with a bioptic telescope has been
undertaken in a range of areas, chronologically presented
as preference for type, usage, facial feature recognition and
target detection.
Analysing the use of the Ocutech VES bioptic telescopes,
Greene et al. (1991) completed a controlled cross-over
clinical study using 24 existing wearers of bioptic telescopes
and 31 new wearers. Existing wearers were provided with
the experimental device, the original manual focus VES
I, in ×3 or ×4, for 16 weeks. New wearers were provided
with the experimental device, the VES, for 8 weeks and a
control device, the Designs for Vision ×3 and ×4 bioptic
telescopes or an astronomical bioptic telescope of ×2.75
and ×4 magnification, for 8 weeks. The majority, 71%,
preferred the VES, with those younger than 50 years having
a statistically significant preference for the device. Gender,
binocularity, magnification or previous use did not affect
preference. Subjects rated field of view and acuity through
the device as the most important variables in telescope
design. The control device was considered superior for the
field of view while both the control and experimental devices
rated equally for acuity. Interestingly, 71% of new wearers
purchased a bioptic telescope, of which 77% were VES.
Conclusions suggest that, while field of view is paramount,
appearance, weight and ability to adjust the telescope
contributed significantly to bioptic telescope selection
(Greene et al. 1991). Statistical analysis showed a significant
increase in the frequency of telescope use for the same
cohort of wearers in the areas of ‘navigation and mobility’,
‘observation and audience participation’ and ‘intermediate
visual tasks’. For both wearers and new wearers, bioptic
telescopes were most often employed for travel, television,
seeing faces and looking out of a window. Patterns of
bioptic telescope use were found to change over time
(Greene et al. 1993).
Demographics of 69 users of the Ocutech VES-Autofocus
were examined in an attempt to elicit the characteristics
promoting patient satisfaction. Statistical analysis showed
there was no difference in those who purchased and kept
the device and those returning it with respect to gender, age,
acquired or congenital disorder or acuities between 6/21
and 6/60 acuities. On interviewing the 48 subjects who
had kept the device, 43% stated using it at least once a
week. One finding was that with those of acuity 6/120 or
worse, the VES-Autofocus did not improve resolution
sufficiently (Greene et al. 2001).
One of the most frustrating visual disabilities associated
with age-related macular degeneration is the reduced
ability to recognise facial features and facial expression.
In holistic low-vision care, patients are advised to inform
friends and family of their eye condition, get closer to
people, wear a symbol badge and/or use a symbol
white cane. Terjeria et al. (2002) examined the use of
the Ocutech VES-Autofocus to enhance the ability to do this
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M E McClure
task. Thirty subjects with age-related macular degeneration
consented to take part in the study. Their mean distance
visual acuities were 6/36, ranging from 6/15 to
6/120,
and
mean
contrast
sensitivity
depicted
moderate loss of contrast at 0.92 logunits on the
Pelli–Robson chart, ranging from 0.10 to 1.50 logunits.
Carefully selected facial images of well-known figures
were displayed at 4m from the subject and facial feature
recognition was scored with habitual vision and with the
bioptic telescope. Although the facial expression difference
did not assess the subjects’ ability to name the type of
expression as, for example, sad or happy, the subject
selected the one face out of four images that differed in
expression. For the facial feature task, the percentage of
correct recognitions improved from 26% to 68% with the
bioptic telescope. Similarly, there was an increase in those
detecting facial expression differences from 46% to 69%
with the bioptic telescope. Considering these subjects were
novel bioptic telescope users, this excellent study highlights
bioptic telescope benefits in macular disease. Not all
subjects showed improvement and this is likely to be due to
the unfamiliarity of the device, being unable to view easily
through the eyepiece, scan the images and comprehend the
reduced field of view (Terjeria et al. 2002).
Using normally sighted subjects, with simulated visual
impairment of 6/60, bioptic telescope performance
was assessed in target detection in a crowded array of
optotypes and numerals, set at 45° eccentricity. The
experimental design mimicked head and eye movements
involved in driving. The small time difference found
between normal and simulated vision was proposed as
unlikely to affect driving safety. Both groups increased
the speed by which the target was recognised with
repeated presentations. Although only 15 subjects were
used in the study, results imply that it was easy to adapt
to the device and training improved performance.
Interestingly, one subject was reviewed 2 years later and
showed the same performance (Tadin et al. 2008).
Case reports of bioptic telescope use
While individual cases do not provide an evidence base for
prescribers, the following range of case reports provides
examples of those who have benefited from the fitting of a
bioptic telescope. These cases were presented by poster at
low-vision conferences.
Presenting a case of a 47-year-old male with Stargardt’s
macular dystrophy as a candidate for bioptic telescope
use is not surprising. Binocular visual acuity was 6/120 and
low-vision goals were to enhance tasks in the educational
environment, namely seeing presentations, viewing the
whiteboard and taking notes. Using the Ocutech VES-Sport
×4, 6/12 and N6 were achieved and task performance was
successful (Adamson and Scott-Weideman 2009).
Fitting a 35-year-old female with Hallermann–Streiff
syndrome with a ×4 Galilean bioptic telescope in
conjunction with a range of optical low-vision aids,
Witmeyer and MacDonald (2004) report a return to
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independence and education. With ocular disorders,
associated with the syndrome, of microphthalmia,
keratoglobus, cataracts and glaucoma, refractive error of
+27.00DS and visual acuity of 6/48, this individual would
not fit the typical reasons for trial. This highlights the need
for approaching the criteria for suitable candidates as
guidelines only.
Prescribing a ×4 non-focusable bioptic telescope for a
patient with congenital oculocutaneous albinism and
nystagmus improved visual acuities from 6/60 to 6/9. This
achievement enabled the individual to pursue his goal of
driving in a US state allowing bioptic driving, after intensive
time-consuming training. Visual fields were found to be
normal (Harville 2007).
Conclusions
Bioptic telescopes are currently available to those with
a visual impairment in the UK and thus, the use of
these devices is likely to increase in the future. The epidemic
of age-related macular degeneration in the UK provides
a significant number of potential bioptic telescope users.
Low-vision service providers should understand the
advantages and disadvantages of a bioptic telescope and,
using their specialist knowledge, promote the device to
suitable patients and refer patients for a bioptic telescope
trial. Key facts and figures to recall for suitability are the
visual acuity levels of 6/18–6/75, ocular disorders causing
central visual field loss, psychological acceptance of a
conspicuous spectacle-mounted telescope and prior handling
of a monocular hand-held telescope. By providing a trial,
clinicians prescribing bioptic telescopes offer patients a
chance to know if this optical low-vision aid will provide
the ability to achieve their low-vision goal. The range
of manually focused and set focus ×2.2 to ×6 bioptic
telescopes can provide up to 6 logMAR lines of visual
acuity improvement. Scanning techniques can enhance the
narrow field of view.
The first trial of bioptic telescopes, in 5 subjects of mean
age 12 years and diagnoses of congenital ocular disorders,
found all subjects demonstrated frequent usage and
80% (n = 4) continued using the device after the study
(Kelleher 1974). Thus all age ranges should be considered
for bioptic telescope use. Similarly, 78% of bioptic
telescope users, prescribed as part of a clinical trial, opted
to continue with the device (Greene et al. 2001). While
clinical research has shown evidence that a bioptic telescope
improves ability to perform a range of tasks, current users
are testimony to the benefits of the device in enhancing
vision-related quality of life. Future bioptic telescope designs
are anticipated and it is hoped that further clinical research
will emerge, within the UK, of bioptic telescope usage.
Low-vision service providers should be continually aware
of any legalisation of bioptic driving within further
European countries and for the licensing authorities’ response
in the UK. Optometrists in practice will now have an
increased knowledge of bioptic telescopes with an
understanding of their merits and typical user profile.
Bioptic telescopes
Summary
Located superiorly to the user’s visual axis and
positioned through a drilled aperture in a spectacle
lens, a bioptic telescope is a miniature telescope of
Galilean or astronomical design for use by those
with low vision. The user habitually views through the
spectacle lens for normal viewing and lowers the chin
to view through the eyepiece of the bioptic telescope.
Used mainly as a mobility aid by those with mild
to moderate central visual impairment, a bioptic
telescope provides a magnified image of a distance or
intermediate target and thus improves resolution.
• Bioptic telescopes have been used for improving
performance in an educational, employment,
shopping, travel, social and leisure setting.
• Suitable candidates for a trial of a bioptic
telescope include individuals aged 8 years or over,
who are unconcerned at the cosmetic appearance
of the device.
• Distance visual acuity, ideally better than or equal
to 6/75, and contrast sensitivity of 1.20 logunits
or better on the Pelli–Robson chart are helpful
criteria for those considering a referral for bioptic
telescope fitting.
• Previous low-vision care and, specifically, use of a
hand-held monocular telescope can enhance the
ability of an individual to use a bioptic telescope.
• Bioptic telescope prescribers currently provide a
service across the UK, offering a range of bioptic
telescopes from Ocutech Inc. and Designs for Vision.
These include the manual-focusing Ocutech Vision
Enhancing Systems (VES), known as the VES-K,
VES-Sport and VES-Mini, in magnification ranges
of ×3, ×4 and ×6. The award-winning Ocutech
Autofocus bioptic telescope is currently being
upgraded. The Designs for Vision standard and
wide-angle bioptic telescopes range in magnification
from ×2.2 to ×4.
• Bioptic telescopes have also shown good acceptance
and usage in carefully selected candidates.
Prescribers assess suitable bioptic telescope users
at a trial appointment by seeking a three logMAR
line improvement. Successful fitting is more likely
when the better eye is the dominant eye, the
low-vision goal is an intermediate or distance task
and the user can manually operate the device and is
excited about it.
• Outcomes from clinical studies demonstrate
that bioptic telescopes have improved the ability
to perform navigation and mobility tasks, facial
feature and expression recognition and seeing signs
whilst driving.
• In 39 states of the USA and in the Netherlands,
driving with a bioptic telescope is currently legally
allowed, albeit with intensive driver training and
licence restrictions. The UK does not permit driving
with a bioptic telescope.
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CET Multiple Choice Questions
This article has been approved for one non-interactive point under
the GOC’s Enhanced CET Scheme. The reference and relevant
competencies are stated at the head of the article. To gain your point
visit the College’s website www.college-optometrists.org/oip and
complete the multiple choice questions online.
CPD Exercise
Lowe JB, Rubinstein MP (2000) Distance telescopes: a survey
of user success. Optom Vis Sci 77, 260–9
After reading this article can you identify areas in
which your knowledge of bioptic telescopes has
been enhanced?
Luo G, Peli E (2011) Recording and automated analysis of
naturalistic bioptic driving. Ophthalmic Physiol Opt 31, 318–25
How do you feel you can use this knowledge to offer
better patient advice?
Newman JD (1976) A rational approach to license drivers using
bioptic telescopes. J Am Optom Assoc 47, 510–13
Are there any areas you still feel you need to study
and how might you do this?
Ocutech Inc. (2011) Ocutech Low Vision Frequently Asked
Questions. Available online at: http://www.ocutech.com/
low-vision-consumer-faq.aspx (accessed 18 April 2012)
Which areas outlined in this article would you benefit
from reading in more depth, and why?
Optima Low Vision Services Ltd (2009) Optima Partner
Programme. Available online at: http://www.optima-bioptics.
co.uk/partners.htm (accessed 26 April 2012)
Owsley C, McGwin Jr G (1999) Vision impairment and driving.
Surv Ophthalmol 43, 535–50
Owsley C, McGwin Jr G (2010) Vision and driving. Vision Res 50,
2348–61
Peli E (2001) Vision multiplexing: an engineering approach.
Optom Vis Sci 78, 304–15
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Peli E, Vargas-Martín F (2008) In-the-spectacle-lens telescopic
device. J Biomed Opt 13, 034027
Bioptic telescopes
Reflection
1. What impact has your learning had, or might it have, on:
• your patients or other service users (eg those who refer
patients to you, members of staff whom you supervise)?
• yourself (improved knowledge, performance, confidence)?
• your colleagues?
2. How might you assess/measure this impact?
To access CPD Information please click on the following link:
college-optometrists.org/cpd
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