Dear editor,
I read with interest Catederal et alÃâââìâââs study on the use of polymerase chain reaction (PCR) for detection of Mycobacterium tuberculosis in donor corneal tissues.1 The authors report the presence of M. tuberculosis DNA in donor corneas of patients with no documented history of tuberculosis. However there are several methodological erro...
Dear editor,
I read with interest Catederal et alÃâââìâââs study on the use of polymerase chain reaction (PCR) for detection of Mycobacterium tuberculosis in donor corneal tissues.1 The authors report the presence of M. tuberculosis DNA in donor corneas of patients with no documented history of tuberculosis. However there are several methodological errors in the study which need to be discussed. The most significant flaw is the lack of biological plausibility for the presence of M. tuberculosis in the corneal tissue, which is not known to contain any phagocytic cells, except probably at the limbus. The authors have not mentioned the size of the donor corneal button or the degree of corneal vascularization at the limbus. A large corneal button or presence of significant corneal vascularization could account for the detection of mycobacterial DNA in corneal tissue. Besides, the possibility of ÃâââìÃà contaminationÃâââìâââ of the corneal surface by the aqueous cannot be ruled out.
Even then, the high incidence of M. tuberculosis DNA in ÃâââìÃà TB-negativeÃâââìâââ eyes remains unexplained. The authors make a passing reference to the use of positive and negative controls during each amplification reaction, but the nature of these controls or the outcomes after amplification are not mentioned. Did the authors get accurate results with each of the controls? The basis for selection of non-TB donors is also vague as the authors have pointed out themselves. Finally, the authors refer to the low incidence of ocular tuberculosis (1-2%) in patients with pulmonary tuberculosis. However, it is well known that ocular tuberculosis is very rarely seen in patients with systemic tuberculosis.2 Hence the overall incidence of ocular tuberculosis Ãâââìââ¬à isolated, as well as in association with systemic tuberculosis, needs to be mentioned. To summarize, the issues highlighted by this study need to reviewed in light of the methodological errors and lack of biological plausibility.
Soumyava Basu
References:
1. Catedral EJ, Santos RE, Padilla MD, Fajardo-Ang C. Detection of Mycobacterium tuberculosis in corneas from donors with active tuberculosis disease through polymerase chain reaction and culture. Br J Ophthalmol. 2010;94:894-7
2. Donahue HC. Ophthalmologic experience in a tuberculosis sanatorium. Am J Ophthalmol. 1967;64:742-8
We appreciate the interest of Van Schooneveld et al.1 in our recent
BJO article.2 Our small, retrospective chart review of RP patients treated
off-label with valproic acid is only the first step in the process of
understanding the potential utility of the drug for patients with this
sight-threatening condition, for which there are no current therapeutic
options.
We appreciate the interest of Van Schooneveld et al.1 in our recent
BJO article.2 Our small, retrospective chart review of RP patients treated
off-label with valproic acid is only the first step in the process of
understanding the potential utility of the drug for patients with this
sight-threatening condition, for which there are no current therapeutic
options.
The size and the scope of our article was limited by the nature of a
retrospective chart review, which only allows analysis of follow-up that
occurred within the defined time frame. Additional factors limiting the
scope and length of the study included (1) the logistical and financial
complexity involved in following up patients in two geographically
separated states; (2) the differences in available equipment in the two
institutions; and (3) the importance of sharing a potential new treatment
with the ophthalmic community sooner rather than later.
The retrospective chart review process was begun while the senior
author was at the University of Florida, and because he moved from Florida
to Massachusetts, the analysis was carried out in Massachusetts and
appropriate Institutional Review Board approval from the Massachusetts
site was published in the article.
The valproic acid treatment regimen analyzed retrospectively in the
charts of the seven patients is detailed in the article. Prospective
follow-up was not done, nor is it allowed under the mandate of a
retrospective chart review. To clarify, the treatment of patients with
valproic acid has not been stopped for any of the patients who tolerated
it well (most of the patients). Our retrospective chart review reported on
in the BJO article captured a relatively short period for a slowly
progressive condition like RP, and we recognize that the most rigorous
validation of a therapy will be a well-designed clinical trial. A
prospective, multicenter, randomized, placebo-controlled clinical trial is
in the final stages of preparation3 in the U.S., and we will be
registering this clinical trial very soon at the U.S. clinical trials
website, www.clinicaltrials.gov.
On a separate note, as part of our current clinical practice in
Massachusetts, several RP patients new to our practice have been treated
with valproic acid; our clinical impressions of these new patients are
similar to what was reported in our article.
There is mounting evidence that valproic acid may have potent
neuroprotective properties and have other beneficial effects,4-6 and we
have intensive in vitro and in vivo experiments (including mice models of
RP) underway. The results of our experiments in the context of retinal
degenerative conditions have been reported at recent meetings.7-11 We are
planning to submit these data as articles to peer-reviewed journals.
Our work has been motivated by the spirit of translational research,
with the goal of more quickly identifying a promising therapeutic approach
and stimulating scientific interest and further research, based on
preclinical data and unexpectedly positive vision function observed in a
clinical setting. Repurposing drugs such as valproic acid, which have been
shown to be safe, is an economical and time-efficient way to bring new
treatments to patients.
Sincerely
C. Clemson
R. Tzekov
M. Krebs
J. Checchi
S. Kaushal
References:
1. Van Schooneveld MJ, Van den Born LI, Van Genderen M, Bollemeijer J
-G. Conclusions of Clemson et al. concerning Valproic Acid are premature
(letter). British Journal of Ophthalmology 25 August 2010.
2. Clemson CM, Tzekov R., Krebs M., Checchi JM, Bigelow C, Kaushal,
S. Therapeutic potential of valproic acid for retinitis pigmentosa.
British Journal of Ophthalmology. July 20, 2010 [epub ahead of print -
doi: 10.1136/bjo.2009.175356]
3. See web page at:
http://www.umassmed.edu/VALPROIC_ACID_SHOWN_TO_HALT_VISION_LOSS_IN_PATIENTS.aspx
4. Monti B, Polazzi E, Contestabile A. Biochemical, molecular and
epigenetic mechanisms of valproic acid neuroprotection. Curr Mol
Pharmacol. 2009 Jan;2(1):95-109.
5. Suuronen T, Nuutinen T, Ryhanen T, et al. Epigenetic regulation of
clusterin/apolipoprotein J expression in retinal pigment epithelial cells.
Biochem Biophys ResCommun 2007;357:397-401.
6. Yasuda S, Liang MH, Marinova Z, et al. The mood stabilizers
lithium and valproateselectively activate the promoter IV of brain-derived
neurotrophic factor in neurons. Mol Psychiatry 2009;14:51-59.
7. S Kaushal, SM Noorwez, R Tzekov, D Huang, Y Li, RWen. The Effect of
Valproic Acid in Mouse Models of RP. Invest. Ophthalmol. Vis. Sci. 2010
51: E-Abstract 3735.
8. SM Noorwez, S Kaushal. Dose-Dependent Differential Effect of HDAC
Inhibitors on Yields of Folded P23H and WT Rhodopsin. Invest. Ophthalmol.
Vis. Sci. 2010 51: E-Abstract 5979.
9. SJ Upadhyay, JA Hossain, MP Krebs, P Baciu, S Kaushal. Effect of
HDAC Inhibitors on Oxidative Apoptosis of RPE Cells. Invest. Ophthalmol.
Vis. Sci. 2010 51: E-Abstract 496.
10. GB Peters, III, T Banzon, A Maminishkis, SS Miller, and S
Kaushal. Valproic Acid Decreases Retinal Thickness in AMD Patients and
Increases Fluid Absorption Across Human Retinal Pigment Epithelium in
vitro. Invest. Ophthalmol. Vis. Sci. 2010 51: E-Abstract 4957.
11. S Noorwez, S Kaushal. Dose-Dependent Differential Effect of HDAC
Inhibitors on Yields of Folded Rhodopsin. XIX Biennial meeting of the
International Society of Eye Research (ISER), Montreal, Canada. Abstract
797.
Dear Sir,
With great interest we read the article of Clemson et al. about a new
treatment for retinitis pigmentosa (RP). However, the authors' claim that
their data suggest that valproic acid (VPA) may be an effective treatment
for RP is unfounded and also regrettably misleading for the many desperate
RP-patients. In fact, we are surprised that the editors of the BJO have
published this study in its present form.
Firstly,...
Dear Sir,
With great interest we read the article of Clemson et al. about a new
treatment for retinitis pigmentosa (RP). However, the authors' claim that
their data suggest that valproic acid (VPA) may be an effective treatment
for RP is unfounded and also regrettably misleading for the many desperate
RP-patients. In fact, we are surprised that the editors of the BJO have
published this study in its present form.
Firstly, the design of the study as well as the medical ethical approval
(approved in Massachusetts, but conducted in Florida) is obscure: why were
the patients treated only for a very short time (2 to 6 months), while RP
is a slowly progressive chronic condition? Why were only 7 patients
treated and described as the results were as promising as the authors
claimed? Why was the treatment stopped, as there were no or few side
effects and what happened after the treatment was stopped?
Secondly, the theoretical action of VPA on the dysfunctional
photoreceptors is unsatisfactorily explained and no experimental data on
retinal tissue are provided. Why was the treatment not tested on rats or
mice with RP? In view of the limited life span of these animals,
unequivocal data on the efficacy of VPA could have been provided.
Thirdly, the authors announce their intention to start a controlled
clinical trial with VPA, but no such trial has been registered yet at the
Current Controlled Trials Register. For the RP-patients longing for
treatment, this is very disappointing, to say the least.
Dear Editor,
we have read with great interest the article of Skoloudik and coworkers on
the use of optic nerve ultrasonography in patients with intracranial
hemorrhage (ICH). The primary goal of this study was to investigate the
variations of the optic nerve sheath diameter (ONSD) early after the onset
of ICH. The authors should be commended for pointing out our interest
towards a new parameter (the relative difference be...
Dear Editor,
we have read with great interest the article of Skoloudik and coworkers on
the use of optic nerve ultrasonography in patients with intracranial
hemorrhage (ICH). The primary goal of this study was to investigate the
variations of the optic nerve sheath diameter (ONSD) early after the onset
of ICH. The authors should be commended for pointing out our interest
towards a new parameter (the relative difference between the ONSD measured
3 mm and 12 mm behind the optic disc), which proved to be more sensitive
than the absolute ONSD measurement as a predictor of elevated intracranial
pressure (EICP). However, we would like to outline two important
limitations of the study.
1. The use of CT scan imaging as the standard criterion to assess EICP is
relatively non-specific as patients with similar pictures may have
significantly different levels of ICP depending on several concurrent
factors (e.g. Sedation, hyperosmolar therapy, ventilation, intracranial
compliance). Moreover, although the resistance index in the MCA, as
measured with TCDS, is often related to ICP, it cannot discriminate
between EICP and cerebral vasospasm (1,2).
2. When considering the ONSD relative enlargement, which is a
submillimetric value, one should take the error of measurement into
account. Specifically, the current study finds a 95th percentile of ONSD
relative enlargement of 0.22 mm in healty volunteers, which is below the
median interobserver ONSD difference of other studies (3). Furthermore, to
the best of our knowledge, no previous study has systematically
investigated the ONSD interobserver variability 12 mm behind the globe.
Finally, previous studies have found that, unlike the oedema of the optic
disc, the retrobulbar ONSD is a dynamic parameter which varies almost
concurrently with changes in cerebrospinal fluid pressure (4,5).
Therefore, it is not surprising that the retrobulbar ONSD and its derived
parameters are changed in the hyperacute phase of ICH.
1. Stocchetti N. Could intracranial pressure in traumatic brain
injury be measured or predicted noninvasively? Almost. Intensive Care Med
2007;33:1682-3
2. Rasulo FA, De Peri E, Lavinio A. Transcranial Doppler ultrasonography
in intensive care. Eur J Anaesthesiol Suppl. 2008;42:167-73
3. Shah S, Kimberly H, Marill K, Noble VE. Ultrasound techniques to
measure the optic nerve sheath: is a specialized probe necessary? Med Sci
Monit 2009;15/5):MT63-8
4. Hansen HC, Helmke K. Validation of the optic nerve sheath response to
changing cerebrospinal fluid pressure: ultrasound findings during
intrathecal infusion tests. J Neurosurg 1997;87:34-40
5. Moretti R, Pizzi B, Cassini F, Vivaldi N. Reliability of optic nerve
ultrasound for the evaluation of patients with spontaneous intracranial
hemorrhage. Neurocrit Care 2009;11:406-10
Editor, I read the recent publication by Awan et al. with a great
interest [1]. Awan et al. concluded that "As compliance has been
identified as a major problem methods to improve amblyopia treatment are
needed, possibly by using educational/motivational intervention [1]."
Recently, Lee et al. proposed that
"Poor compliance with occlusion therapy was less likely to achieve
successful outcome [2]." Indeed, "how complianc...
Editor, I read the recent publication by Awan et al. with a great
interest [1]. Awan et al. concluded that "As compliance has been
identified as a major problem methods to improve amblyopia treatment are
needed, possibly by using educational/motivational intervention [1]."
Recently, Lee et al. proposed that
"Poor compliance with occlusion therapy was less likely to achieve
successful outcome [2]." Indeed, "how compliance can be enhanced" is the
topic to be discussed in management of amblyopia [3]. I have a question
whether the using of educational interventional will be successful. As a
simple process without long period for educational session, the compliance
is still low. How can we expect on the additional process? Karlica et al.
recently noted that "Frequent ophthalmologic follow ups are mandatory to
be sure that therapy is performed correctly and to prevent the possible
unfavorable effects of noncompliance [4]."
References
1. Awan M, Proudlock FA, Grosvenor D, Choudhuri I, Sarvanananthan N,
Gottlob I. An audit of the outcome of amblyopia treatment: a retrospective
analysis of 322 children. Br J Ophthalmol. 2010 Aug;94(8):1007-11.
2.Lee CE, Lee YC, Lee SY. Factors influencing the prevalence of amblyopia
in children with anisometropia. Korean J Ophthalmol. 2010 Aug;24(4):225-9.
3. Holmes JM, Repka MX, Kraker RT, Clarke MP. The treatment of amblyopia.
Strabismus. 2006 Mar;14(1):37-42.
4. Karlica D, MatijeviÃÃÃÃÃâÃâ¬Ãà ¾ÃÃÃâÃâÃâ¬Ãá S, GaletoviÃÃÃÃÃâÃâ¬Ãà ¾ÃÃÃâÃâÃâ¬Ãá
D, Znaor L. Parents' influence on the treatment of amblyopia in children.
Acta Clin Croat. 2009 Sep;48(4):427-31.
Dear Editor,
We thank Authors S.C. Carroll et al for their interesting paper on the
Outcomes of orbital blowout fracture surgery in children and adolescents.1
We agree that autonomic symptoms of nausea and vomiting should alert the
clinician to the high likelihood of significant orbital trauma. This
study shows that the overall outcomes for all patients under the age of 20
were good despite delays. However, this is a hete...
Dear Editor,
We thank Authors S.C. Carroll et al for their interesting paper on the
Outcomes of orbital blowout fracture surgery in children and adolescents.1
We agree that autonomic symptoms of nausea and vomiting should alert the
clinician to the high likelihood of significant orbital trauma. This
study shows that the overall outcomes for all patients under the age of 20
were good despite delays. However, this is a heterogeneous group of
patients with orbital floor fractures with and without entrapment. We are
concerned that young patients with muscle entrapment (white eye blow out
fracture) who are at risk of ischemia are not being highlighted in this
paper.
The data in this series does support early intervention for the two
subgroups of trapdoor fractures. These groups included 6 patients with
open trapdoor fractures and 6 patients with linear closed trapdoor and in
which there is a greater risk of presumed muscle ischemia and poorer
outcome. Follow up data was only available for 4 of the 6 linear closed
trapdoor fractures, all of whom received their surgical intervention
within 2 weeks (2 within 2 days); the one that fully recovered did not
have entrapment of their inferior rectus in the fracture and the other 3
were left with residual diplopia in extreme gaze. Those patients with open
trapdoor fractures all had surgery within 8 days and all but 1 regained
full ductions but not all were symptom free. As per your comments in the
discussion, the depressed plate fractures are lower risk and indeed did
have good outcomes despite delayed surgery. In fact, in this series the
significant delays were in this patient group and the trapdoor fractures
were all operated on within 2 weeks.
Previous studies have shown that intervention within 14 days results in
complete recovery of supraductions 2. More recent studies have shown
intervention within 7 days3 or within 24 hours4 also gives complete
resolution of any symptoms of diplopia.
We, therefore, feel it important to highlight that your data does support
intervention for trapdoor fractures within 2 weeks (median 4 days) and we
feel it is possible that some of these patients may have been completely
symptom free if operated on earlier. We would encourage colleagues to
operate on these patients as soon as possible to not only maximise
potential recovery but also to alleviate any vagal symptoms.
1. Carroll SC, Ng SGJ. Outcomes of orbital blowout fracture surgery
in children and adolescents. Br J Ophthalmol 2010; 94: 736-739
2. Bansagi ZC, Meyer DR. Internal orbital fractures in the pediatric
age group: characterization and management. Ophthalmology 2000; 107(5):
829-836.
3. Ethunandan M, Evans BT. Linear trapdoor or "white-eye" blowout
fracture of the orbit: not restricted to children Br J Oral Maxillofac
Surg. 2010 May 12. [Epub ahead of print]
4. Gerbino G et al. Surgical Management of Orbital Trapdoor Fracture
in Pediatric Population. J Oral Maxillofac Surg 2010; 68: 1310-1316.
We congratulate Salowi and colleagues on their study of the use of
CUSUM to monitor competency in cataract extraction (1). However there are
two modifications that could make their system more responsive and
reliable.
Firstly the authors use a CUSUM chart that fluctuates on only one
side of the zero line. Traditionally CUSUM charts fluctuate on both sides
of the zero line (2,3). The consultant in their Figure 1...
We congratulate Salowi and colleagues on their study of the use of
CUSUM to monitor competency in cataract extraction (1). However there are
two modifications that could make their system more responsive and
reliable.
Firstly the authors use a CUSUM chart that fluctuates on only one
side of the zero line. Traditionally CUSUM charts fluctuate on both sides
of the zero line (2,3). The consultant in their Figure 1 performed 48
procedures and 43 were successful while 5 were failures. The weight for a
failure would be -1.791666 and for a success it would be 0.208333.
Figure 1 depicts the traditional CUSUM graph with this data. Against this,
the data from his trainee is also drawn. The trainee CUSUM score keeps
going further and further away from the zero line, suggesting that he has
not reached the bottom of his learning curve. Once his learning is over,
his mean CUSUM line will run parallel to the zero line.
The second modification relates to the decision interval. The authors
discuss in detail the arbitrary decision intervals (control lines) that
they have employed, based on a trade-off between the need to detect poor
performance quickly and that to avoid a large number of false alarms.
Decision lines need not be arbitrary. With the help of computers,
bootstrapping techniques can be employed, so that these lines are placed
where they are statistically meaningful. As an illustration, in Figure 1
with the consultant performance, there were 5 failures and 43 successes.
The 5 failures need not be evenly interspersed among the successes. The
sequence of failures is purely a matter of chance and 2 or even 3 failures
may be clustered together. Bootstrapping allows random reordering of the
failures and successes in a way that the overall numbers of success and
failures are the same for each iteration. The computer can calculate the
maximum and minimum score for each iteration. If a 1000 iterations are
performed it is possible to calculate the mean of the highest scores
(maximum score in the iteration) and the mean of the lowest scores
(minimum score in the iteration) and also the standard deviation around
the means. The upper decision line is the limit drawn with the mean upper
score plus 2SD. The lower decision line is the mean lower score minus 2SD.
If surgery is performed by a person of comparable competence as the
consultant, his CUSUM score will lie within the two decision lines, 95% of
the time.
We have recently used CUSUM for a clinical trial and for this we
developed software that allows for easy bootstrapping, drawing of control
lines and plotting of CUSUM score. This software is available free on the
internet. (http://jacob.puliyel.com/foresee/).
Figure 2 can also be redrawn using the acceptable rate for posterior
capsule rupture (PCR) of 5%. Here the acceptable standard is 1 failure for
19 successes. For Figure 3 using the acceptable rate for impaired vision
as 10% (using data reported by the authors from the Malaysian National
Cataract Surgery Registry) there can be 1 failure for 9 successes.
The software is interactive and allows CUSUM plotting in real time
(meaning that it allows one to see how the CUSUM graph evolves, with each
new success or failure). We hope that the free software available on the
net will encourage more widespread use of CUSUM in various clinical
situations.
Figure 1 Standard reference cumulative sum (CUSUM) showing
performance by a trainee and a consultant can be viewed at
http://jacob.puliyel.com/#paper_199
Reference
1. Salowi MA, Choong YF, Goh PP, Ismail M, Lim TO. CUSUM: a dynamic
tool for monitoring competency in cataract surgery performance. Br J
Ophthalmol. 2010;94:445-9.
2. Van Rij AM, McDonald JR, Pettigrew RA, Putterill MJ, Reddy CK,
Wright JJ. Cusum as an aid to early assessment of the surgical trainee. Br
J Surg. 1995;82:1500-3.
3. Sibanda T, Sibanda N. The CUSUM chart method as a tool for
continuous monitoring of clinical outcomes using routinely collected data.
BMC Med Res Methodol. 2007;7:46.
Ashish Puliyel, Tech Guru gonzoBuzz, Singapore
ashishpuliyel@gmail.com
Jacob Puliyel, Consultant Pediatrician, St Stephens Hospital, Delhi, India
puliyel@gmail.com
Conflict of Interest:
The CUSUM software available free on the internet, was developed by the authors in the context of a clinical trial.
One concept of the PEARS/ WEHE schemes was to increase equity of
access to eye care services across Wales. Any successful scheme which
achieves an increase in access will increase cost, at least in the short-
term, but can prove to be more cost-effective since more expensive
downstream-treatments are avoided as a result of earlier intervention and
patient outcomes are likely...
One concept of the PEARS/ WEHE schemes was to increase equity of
access to eye care services across Wales. Any successful scheme which
achieves an increase in access will increase cost, at least in the short-
term, but can prove to be more cost-effective since more expensive
downstream-treatments are avoided as a result of earlier intervention and
patient outcomes are likely to be enhanced.
Purchasers must judge whether improved access for patients justifies the small additional cost per case (c. ã12-15) and improved access results in more patients being seen in secondary care. In the evaluation, 66% of patients were managed entirely by optometrists without referral to the Hospital Eye Service (HES): previously, these patients may have contributed to unnecessary referrals. Other benefits for patients include convenience, reduced travel time, reduced anxiety and fewer mis-diagnoses.
The change in total cost of primary and secondary eye care following the introduction of these schemes was not quantified. This would have required a randomised protocol comparing costs between intervention and control groups and incorporating a before and after design to capture detailed patient-level data.
Optometrists registered on the schemes at the time of the evaluation had completed seven distance learning modules, four case history scenarios and a clinical-skills assessment. We utilised the results of the evaluation to determine the nature of the re-accreditation training. Optometrists were required to complete six distance learning modules and pass OSCE assessments based on communication, clinical examination and referral. Tutorials were held for those optometrists, identified in the evaluation, who had made inappropriate patient-management decisions. The current cost of training for accreditation is approximately ã200 per optometrist. The impact of this one-off cost is minimal given the number of patients seen under the scheme and was therefore not included in the model.
We hope these comments have further clarified patient-centred
benefits of the schemes.
The Primary Eyecare Acute Referral Scheme, PEARS was introduced in
Wales in in 2003. We welcome the paper by Sheen et al since this presents
an opportunity for the scheme to be appraised and costed.
The authors are open about the weaknesses of their study, such as the
poor response rate to letters sent to GPs. However, there are still
considerable uncertainties about the accuracy of the costings....
The Primary Eyecare Acute Referral Scheme, PEARS was introduced in
Wales in in 2003. We welcome the paper by Sheen et al since this presents
an opportunity for the scheme to be appraised and costed.
The authors are open about the weaknesses of their study, such as the
poor response rate to letters sent to GPs. However, there are still
considerable uncertainties about the accuracy of the costings. It is
likely that the provision of this service will have generated an increase
in the number of patients seen in ophthalmic primary care and a consequent
increase in the number of referrals to the HES thereby increasing costs.
No data is presented in this respect although this could have been sought
from GP or hospital databases.
The authors conclude that the net cost of the scheme is between 10GBP
and 15GBP per patient. What is not made sufficiently clear is that this
is ADDITIONAL cost to the purchaser. PCTs should be discouraged from
implementing this service without first identifying extra funding. It
should not be expected that this service can be paid for from savings made
in the budgets of ophthalmic units.
No mention is made of the training required before optometrists can
embark upon this scheme. It would have been helpful for those considering
such a scheme to have some idea of the nature of and the costs of such
training.
Yours faithfully,
Simon Longstaff
Chairman
Ophthalmic Group Committee
Conflict of Interest:
I am the chairman of the Ophthalmic Group Committee
Sub-Tenon block is a safe, efficient and effective technique for
delivering local anaesthesia for phacoemulsification cataract surgery.[1]
Several studies have compared sub-Tenon's block with topical anaesthesia
for intra-operative pain complications and the technique is found to be
favourable.[2] We are not aware of any published study that has assessed
post-operative pain (beyond 30 minutes post-...
Sub-Tenon block is a safe, efficient and effective technique for
delivering local anaesthesia for phacoemulsification cataract surgery.[1]
Several studies have compared sub-Tenon's block with topical anaesthesia
for intra-operative pain complications and the technique is found to be
favourable.[2] We are not aware of any published study that has assessed
post-operative pain (beyond 30 minutes post-operatively) for routine
phacoemulsification using sub-Tenon's block.
We devised a questionnaire-based survey and asked 56 consecutive
patients to comment on their experience of pain after routine and
uneventful cataract surgery. Surgery was performed by one surgeon (TCD)
and the sub-Tenon's was performed by one anaesthetist (CMK) in all cases.
All patients received sub-Tenon's block using a 2.54cm long metal
posterior sub-Tenon's cannula and 4 cc of 2% lidocaine was used. The
questionnaire was designed to explore parameters of post-operative pain
including severity, character, duration and associated symptoms. Severity
was assessed using a visual analogue score from 0 (no pain) to 10 (severe
pain). The patients were interviewed on the second post-operative day by
telephone. The patients were also asked about any previous eye surgery and
whether they were taking painkillers concomitantly for any other
conditions.
Our results revealed that 51 (91%) patients had suffered no pain
after surgery. However, 31 (61%) were on regular analgesics for other
medical conditions whereas 20 (39%) were not taking any painkillers at
all. Forty one patients had undergone previous cataract surgery. Of the
five patients (9%) who suffered post-operative pain; 2 described immediate
onset, with 1 patient each describing onset at 30 minutes, 2 hours and 24
hours after surgery respectively. Of these, 1 patient had spontaneous
relief, whereas the other 4 required oral analgesia.
There was no notable correlation between those on regular analgesia
and post-operative pain, however, the design and retrospective nature of
the study precludes any conclusions from being drawn in this regard. A
prospective, randomised controlled trial addressing these parameters in
the future would be ideal.
We conclude that our survey supports other studies that the sub-
Tenon's block is not only safe, effective and efficient but also provides
good post-operative pain relief after routine phacoemulsification cataract
surgery.
Dear Editor,
We appreciate the interest of Van Schooneveld et al.1 in our recent BJO article.2 Our small, retrospective chart review of RP patients treated off-label with valproic acid is only the first step in the process of understanding the potential utility of the drug for patients with this sight-threatening condition, for which there are no current therapeutic options.
The size and the scope of...
Dear Sir, With great interest we read the article of Clemson et al. about a new treatment for retinitis pigmentosa (RP). However, the authors' claim that their data suggest that valproic acid (VPA) may be an effective treatment for RP is unfounded and also regrettably misleading for the many desperate RP-patients. In fact, we are surprised that the editors of the BJO have published this study in its present form. Firstly,...
Dear Editor, we have read with great interest the article of Skoloudik and coworkers on the use of optic nerve ultrasonography in patients with intracranial hemorrhage (ICH). The primary goal of this study was to investigate the variations of the optic nerve sheath diameter (ONSD) early after the onset of ICH. The authors should be commended for pointing out our interest towards a new parameter (the relative difference be...
Editor, I read the recent publication by Awan et al. with a great interest [1]. Awan et al. concluded that "As compliance has been identified as a major problem methods to improve amblyopia treatment are needed, possibly by using educational/motivational intervention [1]." Recently, Lee et al. proposed that "Poor compliance with occlusion therapy was less likely to achieve successful outcome [2]." Indeed, "how complianc...
Dear Editor, We thank Authors S.C. Carroll et al for their interesting paper on the Outcomes of orbital blowout fracture surgery in children and adolescents.1 We agree that autonomic symptoms of nausea and vomiting should alert the clinician to the high likelihood of significant orbital trauma. This study shows that the overall outcomes for all patients under the age of 20 were good despite delays. However, this is a hete...
We congratulate Salowi and colleagues on their study of the use of CUSUM to monitor competency in cataract extraction (1). However there are two modifications that could make their system more responsive and reliable.
Firstly the authors use a CUSUM chart that fluctuates on only one side of the zero line. Traditionally CUSUM charts fluctuate on both sides of the zero line (2,3). The consultant in their Figure 1...
Authors response
Dear Sir,
One concept of the PEARS/ WEHE schemes was to increase equity of access to eye care services across Wales. Any successful scheme which achieves an increase in access will increase cost, at least in the short- term, but can prove to be more cost-effective since more expensive downstream-treatments are avoided as a result of earlier intervention and patient outcomes are likely...
Sir,
The Primary Eyecare Acute Referral Scheme, PEARS was introduced in Wales in in 2003. We welcome the paper by Sheen et al since this presents an opportunity for the scheme to be appraised and costed.
The authors are open about the weaknesses of their study, such as the poor response rate to letters sent to GPs. However, there are still considerable uncertainties about the accuracy of the costings....
Dear Editor,
Sub-Tenon block is a safe, efficient and effective technique for delivering local anaesthesia for phacoemulsification cataract surgery.[1] Several studies have compared sub-Tenon's block with topical anaesthesia for intra-operative pain complications and the technique is found to be favourable.[2] We are not aware of any published study that has assessed post-operative pain (beyond 30 minutes post-...
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