2
We read with keen interest the paper by Kageyama et al,[1] which analyzed the
results of performing phacoemulsification with dominant versus non-dominant hand. The
results were also interesting; vitreous loss was higher with dominant hand group (5.9%
vs.3.4%) and opposite in case of endothelial cell loss. Even though vitreous loss has been
similar to a few other reports of conventional superior inc...
2
We read with keen interest the paper by Kageyama et al,[1] which analyzed the
results of performing phacoemulsification with dominant versus non-dominant hand. The
results were also interesting; vitreous loss was higher with dominant hand group (5.9%
vs.3.4%) and opposite in case of endothelial cell loss. Even though vitreous loss has been
similar to a few other reports of conventional superior incision by trainees, there are also
studies that reports lesser percent of vitreous loss (Prasad et al.:2.9%,[2] Corey RP et al:
1.8%,[3] Seward et al: 1.5%,[4] Pedersen et al: 2.1%[5]). The favourable results for non-dominant
hands could have been due to chance since the trainees were not picked up
randomly. Intraoperative complications could have been probably low if trainees were
allowed to operate on all eyes with their dominant hands as in our institution.
Briefly, in our system each operating surgeon operates on two tables with a
microscope set to swing between tables. Two surgeon’s chairs are placed on the sides of
operating tables. While the surgeon operates on one table, another patient is prepared for
surgery on the other table. After completion of surgery, the surgeon swings the
microscope to the other table and operates on the next patient. Assisting nurses are
trained to designate right and left eye surgery patient to right and left tables, respectively.
This automatically makes surgeons sit on temporal side and operate with their dominant
hand. There is no need for repositioning chairs or equipments, increase staff or a high risk
of infection in our system.
References
(1) T Kageyama, S Yaguchi, Y Metori, et al. Visual results and complications of
temporal incision phacoemulsification performed with non-dominant left hand by
junior ophthalmologists. Br J Ophthalmol 2002; 86:1222-1224
(2) Prasad S. Phacoemulsification learning curve: experience of two junior trainee
ophthalmologist. J Cataract Refract Surg 1998; 24:73-77.
(3) Corey RP, Olson RJ.Surgical outcomes of cataract extractions performed by
residents using phacoemulsification. J Cataract Refract Surg 1998; 24:66-72
(4) Seward HC, Dalton R, Davis A. Phacoemulsification during the learning curve:
risk/benefit analysis. Eye 1993 ; 7:164-168.
(5) Pedersen OO. Phacoemulsification and intraocular lens implantation in patients with
cataract. Experiences of a beginning ‘phacoemulsification surgeon’. Acta Ophthalmol
1990; 68:59-64.
I have had one case of post-op endophthalmitis ,which was treated with intravitreal amikacin , following which the eye recovered wonderfully to the drug , but was left with a macular infarction which compromised central vision !
This case revealed to us the proverbial double edged
sword that amikacin is, an excellent drug with a deadly side effect.
Colleagues need to keep this in mind when using amikac...
I have had one case of post-op endophthalmitis ,which was treated with intravitreal amikacin , following which the eye recovered wonderfully to the drug , but was left with a macular infarction which compromised central vision !
This case revealed to us the proverbial double edged
sword that amikacin is, an excellent drug with a deadly side effect.
Colleagues need to keep this in mind when using amikacin intra-vireal , as
it may diminish visual recovery by a substantial amount.
We appreciate the comments of Grzybowski et al. about our article. We
agree that the term "tobacco alcohol amblyopia" is not very accurate and
does not specifically describe the underlying cause of vision loss. It
may also not fit the "historic" description of the condition. However,
the term is still used widely to describe a spectrum characterized by
optic nerve dysfunction and selective involvement of...
We appreciate the comments of Grzybowski et al. about our article. We
agree that the term "tobacco alcohol amblyopia" is not very accurate and
does not specifically describe the underlying cause of vision loss. It
may also not fit the "historic" description of the condition. However,
the term is still used widely to describe a spectrum characterized by
optic nerve dysfunction and selective involvement of the papillomacular
bundle.
This includes toxic optic neuropathies due to medications (e.g.
ethambutol), and nutritional optic neuropathies due to vitamin
deficiency ( B12 and folate). One reason perhaps why the term is still
popular is that cause of vision loss in these patients is often
multifactorial. The evidence of independent toxicity of either alcohol
or tobacco is weak. Many people abuse both substances yet few of them
develop vision problems. We believe that the final step in the
pathophysiology of all these conditions is mitochondrial damage. This is
one reason why the clinical features of this condition is similar to
Leber's heriditary optic neuropathy. Either alcohol or tobacco abuse may
not be enough to cause optic neuropathy especially in patients who
consume amounts within or slightly above the "recommended limit".
Genetic suceptibility caused by either by compromised mitochondrial
function or deficiency of vitamins necessary to detoxify cyanide, formic
acid and oxygen radicals, plays an important role in the pathogenesis of
this condition. We agree that case 2 had mitochondrial optic
neuroapthy, which probably manifested because of heavy smoking.
We did not test these patients with pattern ERG as we believe that mfERG
is a very good tool in differentiating between optic neuropathy and
retinopathy. We did not intend to imply that those patients had only
maculopathy. Rather we believe that the electrophysiological dysfunction
was not limited to the optic nerve as has been demonstrated in
experimental animal models. We did publish a series of patients with
presumed ethambutol-induced optic neuropathy, who also had mfERG
abnormalities [1]. In patients with poor central vision we do enlarge
the fixation target and our technician does monitor fixation during
testing. Therefore, fixation errors are unlikely to be the cause of the
abnormalities.
References
(1) Behbehani R, Affel E, Savino PJ. Multifocal ERG abnormalities
in ethambutol associated vision loss. Br J Ophthalmol. 2005;89:976-82.
Using a chart review, Nyamori and colleagues estimated the incidence
of retinoblastoma in Kenya to be 1:17,000 live births, similar to global
estimates.1 They observed that late presentation was common, often
attributed to poor awareness or socioeconomic barriers which hinder access
to care. We describe a recent project to improve access to eye care for
people living in Western Kenya.
Using a chart review, Nyamori and colleagues estimated the incidence
of retinoblastoma in Kenya to be 1:17,000 live births, similar to global
estimates.1 They observed that late presentation was common, often
attributed to poor awareness or socioeconomic barriers which hinder access
to care. We describe a recent project to improve access to eye care for
people living in Western Kenya.
IcFEM Dreamland Mission Hospital in Kimilili achieved hospital status
in February 20122. With the support of Sabatia Eye Hospital and the
Provincial eye surgeon we then began offering affordable eye surgery once
a month. Demand for eye screening was high with people travelling long
distances to obtain services. In order to reach as many people as
possible, IcFEM engages local stakeholders by setting up community
leadership structures called Local Transformation Units2. These helped us
to obtain the agreement of local Chiefs, Councillors and Public Health
Officers to set up outreach clinics in isolated villages and at local
markets. Before each clinic, posters were put up in shops, pharmacies,
market places and read at public meetings. A team of two nurses and our
resident clinical officer then set up a stall where people could have
their visual acuity tested (using a chart which did not require literacy),
obtain reading glasses or medication, have simple foreign bodies removed
or be booked for surgery at the Mission Hospital.
Between January and July 2012, 751 people aged 2 to 100 years were
screened: 154 at outreach clinics in the villages, 198 at markets in
Kimilili, Kamukuywa and Chwele, and 399 at the hospital. Those being
considered for surgery were booked for assessment at the hospital before
the monthly operating list conducted by a specialist eye surgeon. Overall
115 patients, mean age 68 years, (15% of those screened) underwent
surgery: cataract extraction 106, foreign body removal 5, excision biopsy
2, tarsorrhaphy 1, peritomy 1. In spite of electricity cuts and use of the
emergency generator, only one patient had a complication (dislocated lens)
requiring further surgery. Following an overnight stay, operated patients
were given a talk including use of eye drops and booked for follow up
after two weeks. Complex cases, including children requiring a general
anaesthetic, could be referred to a specialist hospital.
Nyamori and colleagues recommend increasing public awareness of eye
problems and availability of treatment. We hope that the return to remote
villages of mainly elderly patients, some of whom were previously blind
and are now able to see, help in the fields or care for their
grandchildren, will contribute to this.
Rebecca Nightingale BSc, Consultant Physiotherapist
Jane Dobbs FRCP, Medical Superintendent
Clement Kiprop Dip-CMS, Head Clinical Officer
IcFEM Dreamland Mission Hospital
PO Private Bag, Kimilili 50204
Kenya
References
1. Nyamori JM, Kimani K, Njuguna MW, Dimaras H. The incidence and
distribution of retinoblastoma in Kenya. Br J Ophthalmol 2012; 96: 141-143
2. IcFEM www.icfem-mission.org
Acknowledgements
We thank the staff of Sabatia Eye Hospital for their assistance in setting
up the eye department and Dr Simon Daniell for installing the hospital eye
equipment. We acknowledge the dedicated team of specialist eye surgeons
and theatre sisters who with our colleagues at IcFEM Dreamland Mission
Hospital run the eye service. Our thanks also go to Dr Pippa Oakeshott for
her helpful advice.
Conflict of Interest:
Funders:
ROPE (Relief for Oppressed People Everywhere) www.rope.org.uk.
IcFEM ( Interchristian Fellowships' Evangelical Mission) www.icfem-mission.org
In a thought-provoking editorial in BJO entitled “Why is the
amblyopic eye unstable?” C. Hoyt raised two very important issues relating
to the treatment of human amblyopia. First, there is currently no
effective alternative to occlusion therapy for treating amblyopia. Second,
there is considerable “slippage” of visual acuity after cessation of
occlusion therapy. Our sole purpose in responding to this...
In a thought-provoking editorial in BJO entitled “Why is the
amblyopic eye unstable?” C. Hoyt raised two very important issues relating
to the treatment of human amblyopia. First, there is currently no
effective alternative to occlusion therapy for treating amblyopia. Second,
there is considerable “slippage” of visual acuity after cessation of
occlusion therapy. Our sole purpose in responding to this editorial is to
draw attention to some very recent work, showing significant long-term
improvements in visual performance in the adult amblyopic eye that,
potentially, could be adapted for use as an effective alternative to
occlusion therapy.
Visual perceptual learning – improved visual performance on a given
psychophysical task after extensive training – is a well-established
phenomenon in the normal visual system1. This form of learning is often
tightly coupled to stimulus characteristics encoded early in visual
cortex, such as the orientation or spatial frequency (size) of a visual
stimulus. The stimulus specificity of perceptual improvements through
training suggests that some aspect of neural processing -whether it be the
tuning of individual neurons or the weighting of synaptic connections -
remains malleable or ‘plastic’, even in the adult visual system.
Recent studies have shown that this form of neural plasticity is not
restricted to the normal visual system. Indeed, with an appropriate
training regime one can produce a marked improvement in visual performance
of the adult amblyopic eye. Perceptual learning produces a 50-60%
improvement in Vernier acuity (positional acuity) of the adult amblyopic
eye2. Crucially, in some subjects this improvement in Vernier acuity
transfers to other forms of spatial discrimination such as Snellen acuity.
By way of example, one amblyopic observer improved from a pre-training
value of 20/42 (~6/12), attaining 20/20 (6/6) after extensive training on
the Vernier task2. This suggests that the adult amblyopic visual system
retains a great deal more neural plasticity than previously supposed. Such
improvements in visual performance are not limited to acuity tasks. A
longitudinal study found that training on a contrast detection task led to
a 2-fold improvement in the contrast sensitivity of the amblyopic eye,
with minimal “slippage” 12 months after the cessation of training3.
At present, relatively little is known about the benefits of
perceptual learning in childhood amblyopia during the “sensitive period”.
Given the greater degree of neural plasticity in the developing visual
system, one would imagine that the benefits of perceptual learning might
greatly outstrip those observed in the adult population. Having said this,
a recent study on the efficacy of perceptual learning in previously
treated amblyopic children did not support this supposition4. While the
children (aged 7 to 10 – beyond the sensitive period as defined by
Professor Hoyt) showed significant improvements after 7 to 10 sessions,
the results were no better than those of adults. Further work with “fresh”
(untreated) and younger amblyopes is required to corroborate and extend
these initial findings to younger children, and to determine the “dose-
response” function for perceptual learning.
Several large-scale clinical studies in the UK and USA have shown
that standard occlusion therapy is effective in treating human amblyopia.
However, the benefits are far from universal and a significant number of
children (~ one third) gain little or no visual benefit despite protracted
treatment5. This is unfortunate given that occlusion therapy is difficult
to implement, is often associated with some degree of distress to the
child and may have an impact on educational development. As Professor Hoyt
correctly notes in his original editorial, no alternative treatment
strategies currently exist for these individuals. The development of
perceptual learning as a clinical tool may rectify this situation and
provide an alternative method both for the treatment of amblyopia and for
eliminating or reversing “slippage” once treatment has ceased. Moreover,
if the initial perceptual learning studies in children with amblyopia
withstand further experimental scrutiny and deliver encouraging results in
younger and previously untreated children, the 250-year old practice of
‘patching’ the amblyopic eye may be supplanted or at the least
supplemented by a new treatment protocol.
References
1. Fine, I & Jacobs, R.A. (2002) Comparing perceptual learning tasks:
A review. Journal of Vision 2, 190-203.
2. Levi DM (2005) Perceptual learning in adults with amblyopia: A
reevaluation of the critical periods in human vision. Developmental
Psychobiology. 46, 222-232
3. Polat, U., Ma-Naim, T., Belkin, M. & Sagi, D. (2004) Improving
vision in adult amblyopia by perceptual learning. Proceedings of the
National Academy of Sciences of the United States of America 101, 6692-
6697.
4. Li, R.W., Young, K.G., Hoenig, P. & Levi, D.M. (2005)
Perceptual learning improves visual performance in juvenile amblyopia.
Investigative Ophthalmology and Visual Science. 46, 3161-3168.
5. Clarke MP, Wright CM, Hrisos S, Anderson JD, Henderson J,
Richardson SR. (2003). Randomised controlled trial of treatment of
unilateral visual impairment detected at preschool vision screening. BMJ
327, 1251-1256.
Ben S. Webb, Paul V. McGraw Visual Neuroscience Group
School of Psychology
University of Nottingham, UK
Dennis M. Levi School of Optometry
UC Berkeley, USA
We read with great interest the article of Orge and co-workers[1] who
claim a first-ever solution to the problem of non-invasive volumetric
blood flow measurement in the ophthalmic artery. This is a very important
topic both from the clinical and scientific point of view, since blood
supply is an important parameter for example in glaucoma studies. However,
to date for the orbital circulation only the bl...
We read with great interest the article of Orge and co-workers[1] who
claim a first-ever solution to the problem of non-invasive volumetric
blood flow measurement in the ophthalmic artery. This is a very important
topic both from the clinical and scientific point of view, since blood
supply is an important parameter for example in glaucoma studies. However,
to date for the orbital circulation only the blood velocity has been
measurable; from this the resistivity indices can be calculated, but the
volumetric flow cannot be determined because the small diameter of the
orbital vessels does not allow the vessel diameter measurement which is
indispensable for such calculation.
In spite of the novelty of the report and the extensive analysis of
the authors on the possible sources of high variability of volumetric flow
measurements, it appears to us that there are several points which need
further consideration; some of these were analysed in the Editorial by T R
Hedges,[2] but we would like to highlight two additional questions.
For us, a weak point of the study protocol of Orge and colleagues[1] is
their method for the diameter determination of the ophthalmic artery. They
assume the boundaries of the vessel to be where detected movement starts
and ends along the m-mode line; or in other words the vessel boundaries
are taken to be the positions where the grey pixels and colour pixels
touch on this Doppler image. However, we are doubtful whether this
definition is relevant for the required quantitative measurement. The
first point is that for small vessels the width of the colour area
(indicating blood motion) is unfortunately relatively independent of the
true vessel diameter. The width of the superimposed colour area is greatly
influenced by the actual technical parameters used in color Doppler
imaging (pulse repetition frequency, lateral dimension of the ultrasound
beam, colour priority, motion discriminator setting, colour saturation,
brightness, contrast, etc). Our second doubt is that even on the grey-scale part of the image shown by the present authors in their Figure 1, no
vessel wall is seen, unlike the case for typical images of large vessels
like the carotid arteries.
We think that because of these difficulties regarding the
determination of the vessel wall position, Orge and co-workers
overestimate the ophthalmic artery diameter. Their diameter estimate is
2.02 mm on average; but this figure is significantly larger than is
suggested by other evidence. During conventional 10 MHz B-scan diagnostic
examination, the ophthalmic artery is never visible. However for the
dilated ophthalmic vein, in exceptional cases such as in a patient with
carotideo-cavernous sinus fistula, or in a small baby in a bout of
strenuous crying, the vein is then well outlined with a diameter of 1 mm
or above. Thus, we would expect a 2 mm diameter artery to be clearly
visible. As we demonstrated some years ago,[3,4] patients with a
pathologically dilated ophthalmic vein are good candidates for non-
invasive volumetric blood flow measurement. We were able to measure
volumetric blood flow in the orbit of patients with a high flow fistula
(vein diameter around 3-4 mm) using the CVI-Q technique.
Possibly future improvements in spatial resolution may resolve this
difficulty.
In a vessel like the ophthalmic artery there is a further problem in
determination of the average velocity, because the laminar flow in such
small vessels causes a very wide velocity variation within the lumen. In contrast, we note that the colour
spectrum in the figure presented by the authors is almost completely
uniform and does not show higher speed in the centre of the lumen compared
to that close to the vessel wall. This might imply a relatively
insensitivity of velocity discrimination within a small vessel lumen,
which in addition may be of irregular cross-sectional shape (i.e. not
circular) but is only measured in one longitudinal plane. We agree with
the authors that the analysis software is of great importance and may be a
key factor in dealing with this complex situation.
In spite of our reservations mentioned above we, and many other
workers concerned with orbital circulation, are in urgent need of a
reliable solution for volumetric blood-flow determination in the orbit.
The results of Orge and co-workers[1] show that we are probably not far from
a definitive solution.
References
(1) Orge F, Harris A, Kagemann L et al. The first technique for non-
invasive measurements of volumetric ophthalmic artery blood flow in
humans. Br J Ophthalmol 2002;86:1216-9.
(2) Hedges TR. Ophthalmic artery blood flow in humans. The tortuosity and
the variable course of the ophthalmic artery remain a problem. Br J
Ophthalmol 2002;86:1197.
(3) Németh J, Harkányi Z. Color Doppler and color velocity imaging of the
orbital vessels
In: Süveges I, Follmann P, (Eds) XIth Congress of the European Society of
Ophthalmology. Bologna: Monduzzi. 1997:593-6.
(4) Németh J, Süveges I, Harkányi Z. Color Velocity Imaging of Orbital
Blood Circulation
In: Hasenfratz G. (Ed.) Ultrasound in Ophthalmology, Proceedings of the 16th
SIDUO Congress Munich, Germany 1996. Regensburg: Roderer Verlag. 2000:31-3.
We welcome Dua's comments [1] regarding our proposed modification of
the classification of ocular chemical injuries [2], as they help to
highlight the reason why we have sought to modify a classification which
has been used by ophthalmologists for many years, updating it based upon
advances in our understanding of the healing of the ocular surface and
have not attempted to design an entirely new syste...
We welcome Dua's comments [1] regarding our proposed modification of
the classification of ocular chemical injuries [2], as they help to
highlight the reason why we have sought to modify a classification which
has been used by ophthalmologists for many years, updating it based upon
advances in our understanding of the healing of the ocular surface and
have not attempted to design an entirely new system.
His interpretation of our classification is misleading to the
casual reader. It is incorrect that 12 clock hours of limbal involvement
would be graded the same as 3 clock hours. Three clock hours represents ¼
of limbal involvement and therefore, would be classified on the basis of
the most severe sign as grade II, whereas 12 clock hours (greater than
1/3) would be grade III. In the absence of good evidence that a
difference of 1-3 clocks hours of limbal ischaemia or staining carries a
significantly worse prognosis, there seems to be little point in promoting
a complicated semi-analogue sub-classification.
His assertion that the Roper-Hall classification [3] did not take
into account conjunctival involvement is inaccurate. Both Ballen and
Roper-Hall stressed the importance of conjunctival involvement [4,3]. Dr Dua
further states that assessment of the tarsal conjunctiva is impractical.
This is an integral part of the assessment, both to locate noxious foreign
bodies and to identify the possibility of future symblepharon formation,
particularly if contiguous bulbar and tarsal conjunctiva are affected. As
has recently become apparent, the tarsal conjunctiva plays a pivotal role
in maintaining the health of the ocular surface [5,6]- hence the inclusion
of the tarsal conjunctival area in our classification.
Dua also misinterprets the quantification of corneal damage. He
admits that corneal haze is an indicator of severity of injury and of the
offending chemical but has not included it in his classification [7]. To
reduce or disregard the importance of corneal involvement, without good
evidence to the contrary, is unsupported. Both Roper-Hall and Ballen
recognized the importance of corneal damage [3,4] , hence its retention in
our modified classification. Furthermore, the assertion that many
chemical injuries involving more than 3 to 6 clock hours of the limbus
with a clear cornea would not be catered for in our classification is
inaccurate: they would comprise greater than 1/3 limbal injury and be
classified on the basis of the most severe sign as Grade III.
We retained limbal ischaemia in our classification as it has been
validated as a prognostic indicator in the original Roper-Hall
classification and provides continuity with it. We do not promote limbal
staining as evidence of ischaemia, because there is no evidence that it is
a better indicator of limbal stem cell damage. Indeed the evidence would
favour limbal ischaemia [3,4]. Therefore, there is no issue in using both
corneal and conjunctival staining to grade the extent of the injury,
precisely because we do not presume that staining represents ischemia or
stem cell failure.
Whilst the effect of a chemical injury may not be fully apparent at
presentation, this in no way invalidates grading or classifying the injury
at presentation. There is no constraint to a chemical injury being graded
as II at presentation and grade III when evaluated at a later date. The
assertion that the modified classification does not allow for variation in
the extent of the conjunctival and limbal injury is flawed. As stated,
the most severe sign dictates the grade.
Dr Dua is incorrect in saying that our proposals are purely theoretical
and not based on clinical experience. We have based them on a widely
accepted classification, which has almost 40 years of clinical use and
have essentially made a few adjustments, while retaining the core
principles.
Without good evidence to the contrary, it would be irresponsible to
disregard a widely accepted grading system. However, the success of such
a classification does not depend on how good the authors perceive it to be
but on how user friendly and reliable it is to the clinicians who deal
first hand with such injuries. We would leave it to the reader to decide
if this has been achieved.
References:
(1) Dua HS. Classification of ocular surface burns :Authors
response.bjophthalmol.com 2004.
http:/bjo.bmjjournals.com/cgi/eletters/85/11/1379#219
(2) Harun S et al. Classification of ocular surface burns
electronic response to Dua et al. (A new classification of ocular surface
burns).bjophthalmol.com 2004.
http:/bjo.bmjjournals.com/cgi/eletters/85/11/1379#219
(3) Roper-Hall MJ. Thermal and chemical burns. Trans Ophthalmol Soc UK
1965;85:631-53
(4) Ballen PH, Hemstead NY.Treatment of chemical burns of the
eye.Eye,Ear, Nose and Throat Monthly 1964;43:57-61
(5) Wirtschafter JD., Ketcham JM, Weinstock RJ, et al. Mucocutaneous
junction as the major source of replacement palpebral conjunctival
epithelial cells. Inv Ophth Visual Science. 40(13):3138-46, 1999 Dec.
(6) Wei ZG, Wu RL, Lavkar RM, et al. In vitro growth and
differentiation of rabbit bulbar, fornix and palpebral conjunctival
epithelia. Implications on conjunctival epithelial transdifferentiation
and stem cells. Inv Ophth Visual Science 1993 Apr;34(5):1814-1828
(7) Dua HS, King AJ, Joseph A. A new classification of ocular surface
burns. BJO 2001;85:1379-1383
According to the Canadian Community Health Survey, approximately 82%
of the population of seniors aged 65 – 80+ (3,000,000 seniors) reported
having vision problems in Canada. [1] Cataracts are the leading cause of
vision impairment among seniors. Between the period of 1994 – 2003,
proportions of seniors with cataracts rose from 14% – 20% with populations
aged 75 and over accounting for higher percentage...
According to the Canadian Community Health Survey, approximately 82%
of the population of seniors aged 65 – 80+ (3,000,000 seniors) reported
having vision problems in Canada. [1] Cataracts are the leading cause of
vision impairment among seniors. Between the period of 1994 – 2003,
proportions of seniors with cataracts rose from 14% – 20% with populations
aged 75 and over accounting for higher percentages. [1]
Cataract surgery is among non-emergency surgical procedures with
highest wait times in Canada. There was a 32% increase in cataract
surgeries over 5 years between 1997/1998 and 2002/2003. In British
Columbia, there were 11,816 patients waiting for surgery and 7897 patients
completed in the 3 months from 31 August 2006 to 31 October 2006. [2] In
addition to being a barometer of accessibility to health care services,
cataract wait times are also a determinant of patient satisfaction which
in turn is correlated with increased health-related quality of life [3]
and possibly decreased injury risk. [4]
Delay of care is a persistent and undesirable feature of current
health care systems. [5] Waits and delays plague health care systems
worldwide, and wait times for most specialists exceed those for primary
care practices. [6] From clinical perspective delay in necessary treatment
due to surgical wait lists is a major concern. [7] Establishing a
clinically appropriate time that patients can safely wait for the
operation is generally perceived as a method to prevent adverse outcomes
of delay. [8]
The cost effectiveness of cataract surgery has been well-established.
[9, 10] In fact, modern techniques used for cataract surgery today result
in rapid visual improvement with 50% of patients experiencing good vision
by 24 hours and 96-99% experiencing good vision by 4 weeks. [11] Evidence
supports cataract surgery among older drivers in producing significant
improvements in driving performance (best predicted by the concomitant
improvement in contrast sensitivity), subsequent crash rates half that of
older drivers with cataracts who opted not to have surgery, and self-reported improved visual function and distance estimation. [4]
References
(1). Millar, W. J. Vision problems among seniors. Health Reports. 2004;
16; 45-49.
(2). BC Ministry of Health (2006). Surgical Wait Times: Cataract
Surgery in BC. [Online]. Available at URL:
http://www.swl.hlth.gov.bc.ca/swl/swl_db/swl.WaitlistPkg.GetHospitalListBySurgSpecNLF?IEvent=27
(3). Conner-Spady, B.L., Sanmugasunderam, S., Courtright, P.,
McGurran, J.J., & Noseworthy, T.W. Determinants of patient
satisfaction with cataract surgery and length of time on the waiting list.
British Journal of Ophthamology. 2004; 88; 1305-1309.
(4). Owsley, C., McGwin, G., Sloane, M., Wells, J., Stalvey, B.T.,
Gauthreaux, S. Impact of cataract surgery on motor vehicle crash
involvement by older adults. JAMA. 2002; 21; 288(7):841-9.
(5). Hodge, W., Horsley, T., Albiani, D., Baryla, J., Belliveau, M.,
Buhrmann, R., O'Connor, M., Blair, J., Lowcock, E. The consequences of
waiting for cataract surgery: a systematic review. CMAJ. 2007 176: 1285 -
1290.
(6). Murray, M.F. Improving access to specialty care. Jt Comm J Qual
Patient Saf. 2007; 33(3):125-35.
(7). Sobolev, B., Mercer, D., Brown, P., FitzGerald, M., Jalink, D.,
Shaw, R. Risk of emergency admission while awaiting elective
cholecystectomy. CMAJ. 2003; 169; 662–665.
(8). MacCormick, A.D., Collecutt, W.G., Parry, B.R. Prioritizing patients
for elective surgery: a systematic review. ANZ J Surg. 2003; 73; 633–642.
doi: 10.1046/j.1445-2197.2003.02605.x.
(9). Laidlaw, D.A.H., Harrad, R.A., Hopper, C.D., Whitaker, A.,
Donovan, J.L., Brookes, S.T., Marsh, G.W., Peters, T.J., & Sparrow, J.
M. Randomised trial of effectiveness of second eye cataract surgery.
Lancet. 1998; 352; 925-929.
(10) Sach, T.H., Foss, A., Gregson, R., Zaman, A., Osborn, F., Masud,
T., Harwood, R.H. Falls and health status in elderly women following first
eye cataract surgery: an economic evaluation conducted alongside a
randomised controlled trial. Br J Ophthalmol. 2007 Jun 21; [Epub ahead of
print]
(11). Harwood, R. H., Foss, A. J. E., Osborn, F., Gregson, R.M.,
Zaman, A., & Masud, T. Falls and health status in elderly women
following first eye cataract surgery: A randomized controlled trial.
British Journal of Ophthamology. 2005; 85; 53-59.
I read the paper entitled "Risk of selected eye diseases in people
admitted to hospital for hypertension or diabetes mellitus: record linkage
studies" with interest. It elucidated that diabetes mellitus has a risk of
several ocular diseases with significance using two big epidemiological
data. However, I have two queries on their outcome by selecting the
association between cataract and diabetes mellitus.
I read the paper entitled "Risk of selected eye diseases in people
admitted to hospital for hypertension or diabetes mellitus: record linkage
studies" with interest. It elucidated that diabetes mellitus has a risk of
several ocular diseases with significance using two big epidemiological
data. However, I have two queries on their outcome by selecting the
association between cataract and diabetes mellitus.
First, Goldacre et al. described rate ratios concerning several eye
diseases caused by hypertension or diabetes mellitus. For example, risk of
cataract in diabetes was high presenting rate ratio (95% confidence
interval) of 2.95 (2.75 to 3.16) and 2.30 (2.24 to 2.35) in their two
epidemiological datasets (1). Although sex, age, year of admission and
patients' area of residence was adjusted by matching procedure, their
outcome is a hospital-based case control study with no specification on
the type of cataract. Mukesh et al. conducted a follow-up study, and
diabetes mellitus and having taken calcium channel blockers for longer
than 5 years were independent risk factors for posterior subcapsular
cataract (2), presenting hazard ratio (95% confidence interval) of 2.9
(1.7-5.1) and 2.9 (1.2-6.9), respectively. In addition, hazard ratio (95%
confidence interval) of age by one year increase for posterior subcapsular
cataract was 1.09 (1.07-1.1) (2). Effect of confounding variables on the
association between cataract and diabetes mellitus are more understandable
in cohort study compared with case-control study as mentioned above.
Second, Goldacre et al. described the study limitation for the lack
of information on the clinical state of diabetes mellitus including
treatment (1). The information on the clinical state of diabetes mellitus
is useful in combination with diabetic retinopathy.
The hospital-based case control study has a merit of satisfactory
statistical power, and further study on the association between cataract
and diabetes mellitus should be conducted including the above mentioned
information.
References
1. Goldacre MJ, Wotton CJ, Keenan TD. Risk of selected eye diseases
in people admitted to hospital for hypertension or diabetes mellitus:
record linkage studies. Br J Ophthalmol 2012;96:872-6.
2. Mukesh BN, Le A, Dimitrov PN, et al. Development of cataract and
associated risk factors: the Visual Impairment Project. Arch Ophthalmol
2006;124:79-85.
Klein and colleagues show a significant correlation between blood
pressure – both systolic and diastolic – and intraocular pressure
(IOP).[1] Law et al. recently showed that blood pressure lowering drugs
prevent a significant proportion of headaches; however, the causal
relation between hypertension and headache – whether migrainous or non-
migrainous -- remains ambiguous.[2] In the absence of a clear...
Klein and colleagues show a significant correlation between blood
pressure – both systolic and diastolic – and intraocular pressure
(IOP).[1] Law et al. recently showed that blood pressure lowering drugs
prevent a significant proportion of headaches; however, the causal
relation between hypertension and headache – whether migrainous or non-
migrainous -- remains ambiguous.[2] In the absence of a clear link between
headache and hypertension, hypertensive headache has also been regarded as
a myth or “socio-psychological” disorder[3] despite a typical circadian
pattern and throbbing character.[2]
A statistically significant inverse relation between blood pressure –
both systolic and diastolic -- and non-migrainous headache in a large
cross-sectional study[4] indicates that there is a third, critical,
idiosyncratic perfusion-related variable between hypertension and
headache. Migraine is not a pan-trigeminal disorder.[5,6] In humans, pain
and temperature fibers from only the ophthalmic area descend to the lower
limit of the first cervical spinal segment; this long held view is
supported by sectional studies at and below the obex for severe trigeminal
neuralgia. Nuchal pain in migraine or hypertensive headache likely
involves ophthalmic nerve fibres.[6] Additionally, photophobia of migraine
is a reflex involving the ophthalmic nerve. Third, ipsilateral migraine
aura or headache has never been reported following enucleation or
evisceration of the eye.[5,6] Dental extraction (upper or lower jaw) is
only rarely associated with migrainous headache.[7] Headache, migrainous
or non-migrainous, primarily involves the ophthalmic division of the
trigeminal nerve.[5,6]
A nexus between migraine, autonomic dysfunction, and IOP has been
recently proposed.[6] Autonomic hypofunction prevails in migraine patients
and can underlie sudden ocular choroidal congestion in diverse stressful
clinical circumstances; mechanical deformation of the corneo-scleral
envelope might generate both the scintillating scotoma as well the
headache of migraine.[5,6] Remarkably, a higher blood pressure is
correlated with a higher IOP.[1] Tamponade function of IOP maintains
ocular integrity; a higher IOP limits ocular choroidal hyperperfusion and
possibly prevents the development of headache at relatively higher levels
of blood pressure. Every physiological function has an upper threshold;
the tamponde effect of rising IOP is probably overwhelmed in severe or
malignant hypertension, hypertensive encephalopathy, and pheochromocytoma-
related surges of blood pressure.[8]
The common action by which migraine prophylactic agents prevent
attacks likely involves a lowering of the IOP; propranolol, atenolol,
metoprolol, nadolol, clonidine, flunarizine, verapamil, diuretics and
angiotensin converting enzyme inhibitors lower IOP.[1,5,6] Intriguingly,
the prophylactic effect of migraine preventing agents is not predictable
or dose-dependent, a feature that might reflect the ceiling effect in
lowering IOP. Also, lowering IOP beyond a certain critical threshold –
that varies for every individual – can aggravate the tendency to develop
ocular choroidal congestion and mechanical deformation of the pressure-sensitive ophthalmic nerve fibers of the iris and the chamber angle.
Vasodilating anti-hypertensive agents like nifedipine, hydralazine, and
enalapril commonly induce headache possibly by a combination of lowering
the IOP and inducing choroidal congestion.
Rather than being a simple function of blood pressure, headache in
hypertension patients appears to be the outcome of a complex interaction
between autonomic function, choroidal perfusion and IOP, the many trait-
and state-dependent factors that determine the mechanical properties of
the corneo-scleral envelope, and the endogenous pain control mechanism.[8] Hypertension-associated headache – migrainous or non-migrainous,
spontaneous or antihypertensive drug-induced -- is not “all in the mind”;
a clear link with variations of the IOP appears to be emerging.
References
1. Klein BEK, Klein R, Knudtson MD. Intraocular pressure and systemic
blood pressure: longitudinal perspective: The Beaver Dam Eye Study. Br J
Ophthalmol 2005;89:284-7.
2. Law M, Morris JK, Jordan R, Wald N. Headaches and the treatment of
blood pressure. Results from a meta-analysis of 94 randomized placebo-
controlled trials with 24 000
participants. Circulation 2005;112:2301-6.
3. Friedman D. Headache and hypertension: refuting the myth. J Neurol
Neurosurg Psychiatry 2002;72:431.
4. Hagen K, Stovner LJ, Vatten L, Holmen J, Zwart J-A, Bovim G. Blood
pressure and risk of headache: a prospective study of 22 685 adults in
Norway. J Neurol Neurosurg Psychiatry. 2002;72:463-466.
5. Gupta VK. Lamotrigine, migraine aura and headache: tightening the
Gordian knot of primary headache? J Neurol Neurosurg Psychiatry. (28
November 2005). Available at:
http://jnnp.bmjjournals.com/cgi/eletters/76/12/1730#764
6. Gupta VK. Migrainous scintillating scotoma and headache is ocular
in origin: a new hypothesis. Med Hypotheses. 2005 (In press). Available
online 13 December 2005.
7. Strauss RA, Eschenroeder TA. Hemiplegic migraine following third
molar extractions under intravenous sedation. J Oral Maxillofac Surg
1989;47:184-6.
8. Gupta VK. Does the mysterious link between hypertension and
headache lie at the level of the eye? Circulation (In press).
Dear Editor
2 We read with keen interest the paper by Kageyama et al,[1] which analyzed the results of performing phacoemulsification with dominant versus non-dominant hand. The results were also interesting; vitreous loss was higher with dominant hand group (5.9% vs.3.4%) and opposite in case of endothelial cell loss. Even though vitreous loss has been similar to a few other reports of conventional superior inc...
Dear Editor
I have had one case of post-op endophthalmitis ,which was treated with intravitreal amikacin , following which the eye recovered wonderfully to the drug , but was left with a macular infarction which compromised central vision ! This case revealed to us the proverbial double edged sword that amikacin is, an excellent drug with a deadly side effect. Colleagues need to keep this in mind when using amikac...
Dear Editor
We appreciate the comments of Grzybowski et al. about our article. We agree that the term "tobacco alcohol amblyopia" is not very accurate and does not specifically describe the underlying cause of vision loss. It may also not fit the "historic" description of the condition. However, the term is still used widely to describe a spectrum characterized by optic nerve dysfunction and selective involvement of...
Using a chart review, Nyamori and colleagues estimated the incidence of retinoblastoma in Kenya to be 1:17,000 live births, similar to global estimates.1 They observed that late presentation was common, often attributed to poor awareness or socioeconomic barriers which hinder access to care. We describe a recent project to improve access to eye care for people living in Western Kenya.
IcFEM Dreamland Mission Hos...
Dear Editor,
In a thought-provoking editorial in BJO entitled “Why is the amblyopic eye unstable?” C. Hoyt raised two very important issues relating to the treatment of human amblyopia. First, there is currently no effective alternative to occlusion therapy for treating amblyopia. Second, there is considerable “slippage” of visual acuity after cessation of occlusion therapy. Our sole purpose in responding to this...
Dear Editor
We read with great interest the article of Orge and co-workers[1] who claim a first-ever solution to the problem of non-invasive volumetric blood flow measurement in the ophthalmic artery. This is a very important topic both from the clinical and scientific point of view, since blood supply is an important parameter for example in glaucoma studies. However, to date for the orbital circulation only the bl...
Dear Editor
We welcome Dua's comments [1] regarding our proposed modification of the classification of ocular chemical injuries [2], as they help to highlight the reason why we have sought to modify a classification which has been used by ophthalmologists for many years, updating it based upon advances in our understanding of the healing of the ocular surface and have not attempted to design an entirely new syste...
Dear Editor
According to the Canadian Community Health Survey, approximately 82% of the population of seniors aged 65 – 80+ (3,000,000 seniors) reported having vision problems in Canada. [1] Cataracts are the leading cause of vision impairment among seniors. Between the period of 1994 – 2003, proportions of seniors with cataracts rose from 14% – 20% with populations aged 75 and over accounting for higher percentage...
I read the paper entitled "Risk of selected eye diseases in people admitted to hospital for hypertension or diabetes mellitus: record linkage studies" with interest. It elucidated that diabetes mellitus has a risk of several ocular diseases with significance using two big epidemiological data. However, I have two queries on their outcome by selecting the association between cataract and diabetes mellitus.
First,...
Dear Editor,
Klein and colleagues show a significant correlation between blood pressure – both systolic and diastolic – and intraocular pressure (IOP).[1] Law et al. recently showed that blood pressure lowering drugs prevent a significant proportion of headaches; however, the causal relation between hypertension and headache – whether migrainous or non- migrainous -- remains ambiguous.[2] In the absence of a clear...
Pages