I was delighted to read Dr Okada’s reply to my letter.[1] At the risk of
transgressing from the point of the original article [2] that dealt with a
novel technique to administer triamcinolone to a wide group of patients
with uveitis, I would like to reply:
1. The WHO guidelines are indeed silent on the treatment of latent
tuberculosis which can be defined as merely positive mantoux tests w...
I was delighted to read Dr Okada’s reply to my letter.[1] At the risk of
transgressing from the point of the original article [2] that dealt with a
novel technique to administer triamcinolone to a wide group of patients
with uveitis, I would like to reply:
1. The WHO guidelines are indeed silent on the treatment of latent
tuberculosis which can be defined as merely positive mantoux tests with no
clinical, microbiological, or radiographic evidence of active tuberculosis
(TB).[3] These patients may be treated with single or two drug therapy to
prevent progression to active TB [4] but patients with an active uveitis
would not fall within this definition and probably should be treated as
patients with active extrapulmonary TB irrespective of the detection or
otherwise of an infective focus. The absence of a detectable focus of
systemic TB (usually pulmonary) should not lead to a diagnosis of latent
tuberculosis.
In patients suspected of ocular TB, the findings of systemic TB especially
in those patients with infective manifestations (like choroidal tubercles)
, suggests the need to receive the full four drug regime but considerable
latitude exists in those patients in whom there is neither a detectable
systemic focus or microbiologic evidence. As ocular TB has been known to
occur even in the absence of systemic foci,[5] it may be prudent to
advise a full four drug course rather than one/ two drug regimes.
Inadequate regimes would lead to the development of microbial resistance
and subsequent therapeutic difficulties.
2. The authors theorize that certain cases may be due to an immune
reaction to
sequestered mycobacterial antigen. Recent mouse models have demonstrated
an initial pulmonary infection followed by the appearance of bacteria at
the draining lymph nodes, at which stage a T cell immune response is
generated.[6] Does this response lead to the release of antigen into the
bloodstream leading to the sequence of events we describe as ocular TB? A
mantoux test would probably be positive in these patients indicating
recent infection (but not necessarily active disease) but whether they
would need antitubercular (as opposed to only immunosuppressive agents)
drugs remains unknown.
References
1. Okada AA and Wakabayashi T. Trans-Tenon's retrobulbar triamcinolone infusions in uveitis [electronic response to Okada et al. Trans-Tenon’s retrobulbar triamcinolone infusion for the treatment of uveitis] http://bjo.bmjjournals.com/cgi/eletters/87/8/968#210
2. AA Okada, T Wakabayashi, Y Morimura, S Kawahara, E Kojima, Y Asano
and T Hida. Trans-Tenon’s retrobulbar triamcinolone infusion for the
treatment of uveitis. Br J Ophthalmol 2003; 87:968-971.
3. American Thoracic Society. Diagnostic Standards and Classification of
Tuberculosis in Adults and Children. Am. J. Respir. Crit. Care Med 2000;
161(4): 1376-1395.
4. Small PM. Fujiwara PI. Management of Tuberculosis in the United States.
N Engl J Med. 2001; 345:189-200.
5. Sarvananthan N, Wiselka M, Bibby K. Intraocular tuberculosis without
detectable systemic infection. Arch Ophthalmol. 1998;116(10):1386-8.
6. Chackerian AA, Alt JM, Perera TV, Dascher CC, Behar SM. Dissemination
of Mycobacterium tuberculosis Is Influenced by Host Factors and
Precedes the Initiation of T-Cell Immunity. Infection and Immunity.2002,
70(8): 4501-4509.
I read with great interest the article by Isenberg et al.[1] on "A
double
application approach to ophthalmia neonatorum prophylaxis." The authors
deserve to be commended for their pioneering interest in childhood
blindness. There are certain points that I would like to clarify and
supplement with regard to their study.
1. The authors have mentioned that only babies born by a vagin...
I read with great interest the article by Isenberg et al.[1] on "A
double
application approach to ophthalmia neonatorum prophylaxis." The authors
deserve to be commended for their pioneering interest in childhood
blindness. There are certain points that I would like to clarify and
supplement with regard to their study.
1. The authors have mentioned that only babies born by a vaginal
delivery
were studied, since the eyes of babies delivered by caesarean section
were
previously proved to be nearly always sterile. This would result in a
gross underestimation of the incidence of ophthalmia neonatorum in this
study, for the following reason.
By convention, ophthalmia neonatorum is defined as conjunctivitis
arising within one month after birth.2 Hence, some of these conjunctival
infections could originate from sources other than the maternal vaginal
and cervical flora. In fact, some cases of ophthalmia neonatorum
especially those caused by Staphylococcus aureus could have originated
at
home, as previously reported by the authors themselves.2 In the same
study, no significant difference in the frequency or type of infection
was
seen among the infants delivered vaginally or by caesarean section.[2]
Other authors, too have made similar observations. Krohn et al.[3]
have
found some cases of ophthalmia neonatorum to have been acquired from the
infants' nasopharyngeal passages or from their care givers after birth.
Verma et al.[4] in a prospective study from India, found no correlation
between the microbiology of the conjunctival swabs of the infected eyes
(Staphylococcus aureus was the commonest isolate) and the vaginal and
cervical swabs of the mothers (Escherichia coli was the commonest
isolate). They concluded that most of the cases of ophthalmia neonatorum
were acquired postnatally.
In the light of these previously reported studies, I feel that exclusion
of cases that were delivered by caesarean section was not warranted and
weakens the power of this study. The efficacy of the second drop of
povidone iodine was not tested on a significant proportion of the cases
of
ophthalmia neonatorum (those cases affecting the babies delivered by
caesarean section).
2. It would be relevant to note the percentage of ophthalmia
neonatorum
cases with neonatal dacryocystitis due to congenital nasolacrimal duct
obstruction in this series. Such cases obviously would not have
benefited
from a second drop of povidone-iodine.
3. The Indian study by Verma et al. l4 found a seasonal incidence to
ophthalmia neonatorum with two peaks: in the February and May-June, in
most probability due to the monsoon and the hot tropical climate with
the
attendant eye seeking flies. It would be interesting to know whether any
such seasonal variation was noted in this study that was carried out in
Kenya, a country with a hot tropical climate, like India. If so, the
efficacy of the second drop could be investigated again during such
peaks.
Vasumathy Vedantham MS, DNB, FRCS
Retina - Vitreous Service, Aravind Eye hospital and Postgraduate
Institute
of Ophthalmology
1, Anna Nagar, Madurai - 625 020, Tamilnadu, India.
Telephone: 0452-2532653
Fax: 0452-2530984
Email: drvasumathy@yahoo.com
References
1. Isenberg SJ, Apt L, Signore M Del, Gichuhi S, Berman NG. A double application approach to ophthalmia neonatorum prophylaxis. Br J Ophthalmol 2003;87(12): 1449-1452.
2. Isenberg SJ, Apt L,Wood M. A controlled trial of povidone-iodine as prophylaxis against ophthalmia neonatorum. N Engl J Med 1995;332:562-6.
3. Krohn MA, Hillier SL, Bell TA, Kronmal RA, Grayson JT. The bacterial etiology of conjunctivitis in early infancy. Am J Epidemiol 1993;138:326-32.
4. Verma M, Chhatwal J, Vareghese PV. Neonatal conjunctivitis: a
profile.
Indian Pediatr 1994;31(11): 1357-61.
We thank Dr Doft, et al. for their useful and expert opinion. The
choice of which agent to use to empirically treat gram-negative organisms
implicated in endophthalmitis remains controversial. As amikacin has been
proven to cause macular infarction, we feel one should look at viable
alternatives.
Ceftazidime is already in widespread use in the UK and appears not only to
have an excellent safe...
We thank Dr Doft, et al. for their useful and expert opinion. The
choice of which agent to use to empirically treat gram-negative organisms
implicated in endophthalmitis remains controversial. As amikacin has been
proven to cause macular infarction, we feel one should look at viable
alternatives.
Ceftazidime is already in widespread use in the UK and appears not only to
have an excellent safety profile but also good clinical effect.
Unfortunately until we have proper in vivo and in vitro “head-to-head”
comparison studies, it is difficult to know which is the more efficacious
agent. As far as synergism is concerned, vancomycin and ceftazidime are
usually not tested together because vancomycin acts on gram-positive
organisms and ceftazidime is used primarily for gram-negative infections.
However, there is however one study that reported synergy between
vancomycin and ceftazidime against gram-positive organisms.[1]
The study by Kwok and colleagues raises a concern that ceftazidime
precipitation, as assessed by in-vitro studies, may affect its action in
vivo.[2] The authors of our study have noticed temporary precipitants in
vivo without apparent alteration of clinical effect. (AR)
Previous animal models do show that ceftazidime reaches intravitreal
minimal inhibitory concentrations for common gram-negative microbes after
a single intravitreal injection.3 Perhaps assay at the time of repeat
injection, non-invasive confocal Raman spectroscopy of the anterior
chamber, or further animal models may provide additional insight into
ceftazidime pharmacokinetics and the phenomenon of ceftazidime
precipitation so as to guide future therapeutic choice.
Ultimately the decision lies with the treating surgeon who should be aware
of both the efficacy and safety profiles of the agents available. We still
believe, with the evidence presented in our article, that ceftazidime
currently represents the best agent for the treatment of gram-negative
microbes in endophthalmitis.
References
1. Simon C, Littschwager G. In vitro activity of ceftazidime in
combination with other antibiotics. Infection. 1985 Jul-Aug;13(4):184-9.
2. Kwok AK, Hui M, Pang CP, et al. An in vitro study of ceftazidime
and vancomycin concentrations in various fluid media: implications for use
in treating endophthalmitis. Invest Ophthalmol Vis Sci. 2002
Apr;43(4):1182-8.
3. Mochizuki K, Yamashita Y, Torisaki M, et al. Intraocular kinetics
of ceftazidime (Modacin). Ophthalmic Res. 1992;24(3):150-4.
We read with interest the article by Joussen et al. on the long term
results of retinectomy for the treatment of intractable glaucoma.[1] We
congratulate the authors for studying this innovative method for the
management of refractory glaucoma with a long follow-up of five years.
The high incidence of complications in the study however has aroused
our concerns as only 15.9% of patients...
We read with interest the article by Joussen et al. on the long term
results of retinectomy for the treatment of intractable glaucoma.[1] We
congratulate the authors for studying this innovative method for the
management of refractory glaucoma with a long follow-up of five years.
The high incidence of complications in the study however has aroused
our concerns as only 15.9% of patients completed the study uneventfully.
Further vitreoretinal surgeries were required in 47.7% due to retinal
complications. Moreover, the incidence of hypotony, phthisis and
enucleation was 25%, 20% and 16% respectively and these figures are higher
compared with other treatment modalities like glaucoma implants and
cyclodiode. We have previously studied the use of Ahmed valve implant for
complicated glaucoma, and hypotony, phthisis and enucleation occurred in
10.8%, 3.1% and 1.5% respectively.[2] A recent study on the management of
refractory glaucoma by cyclodiode similarly found a lower rate of hypotony
and phthisis of 9.5% and 5.3% respectively.[3] The high complication
rates in the study by Joussen et al. may be due to the negative case
selection with high incidence of aphakic (30%) and infantile and juvenile
glaucoma (7%). Further controlled study comparing retinectomy with other
treatment modalities may therefore be warranted.
In this evidence-based era, emphasis should be placed on outcomes
which are "patient-oriented evidence that matters" (POEMs).[4] It was
stated by the authors that the main intentions of the surgery were to
relieve pain and to preserve the eye without discomfort. Unfortunately,
these POEMs were not included in the final outcome measures. Instead,
success was determined by "disease-oriented evidences" (DOEs) like
intraocular pressure and retinal attachment which are surrogate
outcomes.[5] These DOEs may not correlate well with the
patients' symptoms and it would be valuable if the authors can include the
level of pain and discomfort as other outcome measures for the study.
References
1. Joussen AM, Walter P, Jonescu-Cuypers CP, et al. Retinectomy for
treatment of intractable glaucoma: long term results. Br J Ophthalmol
2003;87:1094-1103.
2. Lai JS, Poon AS, Chua JK, et al. Efficacy and safety of the Ahmed
glaucoma valve implant in Chinese eyes with complicated glaucoma. Br J
Ophthalmol 2000;84:718-21.
3. Murphy CC, Burnett CA, Spry PG, et al. A two centre study of the dose-
response relation for transscleral diode laser cyclophotocoagulation in
refractory glaucoma. Br J Ophthalmol 2003;87:1252-7.
4. Shaughnessy AF, Slawson DC, Bennett JH. Becoming an information
master: a guidebook to the medical information jungle. J Fam Pract
1994;39:489-99.
5. Temple R. Are surrogate markers adequate to assess cardiovascular
disease drugs? JAMA 1999;282:790-5.
Thanks to Dr Fan and coworkers for their letter and interests in our
article.[1]
The conclusion drawn by us was that confocal microscopy was a rapid and
sensitive diagnostic tool for both early diagnosis and non-invasive
follow
-up of fungal keratitis, not that it was a superior to culture and
corneal
biopsy staining techniques in the early stage of fungal keratitis. It is
rapid compared to
cultu...
Thanks to Dr Fan and coworkers for their letter and interests in our
article.[1]
The conclusion drawn by us was that confocal microscopy was a rapid and
sensitive diagnostic tool for both early diagnosis and non-invasive
follow
-up of fungal keratitis, not that it was a superior to culture and
corneal
biopsy staining techniques in the early stage of fungal keratitis. It is
rapid compared to
culture and biopsy staining techniques, since we were able to detect
fungal
hyphae in all rabbit eyes 2 days after fungal inoculation, but at least 2-3 days had to be elapsed to determine any fungal growth on Sabouraud's
agar. Moreover, O'Day et al[2] reported that about one fourth of fungal
cultures became positive only after 2 weeks. Confocal microscopy is also
rapid compared to biopsy staining, since to perform calcofluor staining
some time had to be elapsed.
As stated in our article [3] 'Although in
our model Sabouraud's agar and corneal biopsy techniques showed similar
sensitivity (100%) in the early stage, confocal microscopy appears to
have
a definitive advantage in the later stages of infection, since not all
cases of fungal keratitis could be cultured.' In the abstract section we wrote that 'on days 14 and 22 confocal microscopy was more sensitive
than
culture technique in both treated and untreated animals, since not all
cases of fungal keratitis could be cultured.' I think the conclusion
drawn
is valid in lights of the data provided in the study. In the second
experiment, 6 rabbits were treated with topical fluconazole, 7 rabbits
were treated with oral fluconazole and 7 rabbits were left untreated. On day 14, we observed hyphal fragments (broken in treated corneas and full size in untreated ones) in each 20 corneas by confocal microscopy.
However, only eight of 20 scrapings grew Aspergillus fumigatus on
Sabouraud's agar culture. The difference between groups was
statistically
significant as appeared in the text by utilizing chi square test.
Similarly, on day 22 confocal microscopy revelaed hyphal fragments
totally
14 corneas out of 20 (three in the topically treated, four in the orally
treated, and 7 in the untreated groups). At this stage only 5 corneal
scrapings grew fungus on culture. The difference was statistically
significant again as appeared in the article by utilizing chi square
test.
Thus, superiority of confocal microscopy over culture technique on days
14
and 22 in treated and untreated rabbits was supported well by the data
presented in the article.
In the result section, we were attempting to determine the
efficacies
of topical and oral fluconazole treatment by culture. However, p values
were not correct as a result of typewriting error. The typewriting
errors
must be escaped both our and reviewer's attentions. However, this part
of
result section does not contain any information that could affect any
conclusion drawn as a result of study data. Actually, this part was not
directly linked to the main aim of the study. The authors wish to thank
to
Dr Fan and coworkers for their careful attentions. The correct p values
were given below.
On day 14 (p=0,383 and p=0,296)
On day 22 (p=0342 and p=0,279).
References
(1) Dorothy SP Fan, David TL Liu, Wai-Man Chan, Dennis SC Lam. Comments on Confocal Microscopy of Aspergillus Fumigatus Keratitis [electronic response to Avunduk et al Confocal microscopy of Aspergillus fumigatus keratitis] bjophthalmol.com 2003http://bjo.bmjjournals.com/cgi/eletters/87/4/409#212
(2) O'Day DM, Akrabawi PL, Head WS, et al. Laboratory isolation
techniques
in human and experimental fungal infections. Am J Ophthalmol. 1979;87:688-93.
We read with great interest the article by G Prakash et al.[1]
We are
trained as residents to overcome this problem by using simcoe cannula and
performing manual irrigation and aspiration through the sideport for
removal of subincisional cortex easily even in the presence of a small
rhexis. We have found this to be a much safer technique than other methods
such as using a J shaped cannula o...
We read with great interest the article by G Prakash et al.[1]
We are
trained as residents to overcome this problem by using simcoe cannula and
performing manual irrigation and aspiration through the sideport for
removal of subincisional cortex easily even in the presence of a small
rhexis. We have found this to be a much safer technique than other methods
such as using a J shaped cannula or bimanual aspiration which need expert
hands.We are further trained to perform phacoemulsification through a
limbal or scleral tunnel which can be extended to accommodate a 5.5mm IOL
and left unsutured thereby giving the benefits of suture less cataract
surgery even by a beginner while learning. Once we have mastered
phacoemulsification we switch over to clear corneal tunnels.
Reference
(1) G Prakash, A Kumar and A Purohit. Unusual case of residual cortical lens matter in anterior
chamber. British Journal of Ophthalmology 2003;87:1421.
I thank Dr Okada et al for replying to my letter to the editor regarding
their article "Trans-Tenon's retrobulbar triamcinolone infusion for the
treatment of uveitis".[1]
While speculating that the cause of the lack of therapeutic response to
sub-tenon’s corticosteroids may be because of placement at a site
relatively far from the target zone, I had quoted only the article by
Freeman et al...
I thank Dr Okada et al for replying to my letter to the editor regarding
their article "Trans-Tenon's retrobulbar triamcinolone infusion for the
treatment of uveitis".[1]
While speculating that the cause of the lack of therapeutic response to
sub-tenon’s corticosteroids may be because of placement at a site
relatively far from the target zone, I had quoted only the article by
Freeman et al.[2]
I fully agree that the article by Jennings et al.[3] had ensured reliable
drug placement. This study was quoted only to highlight the point that
injection of steroids by the sub-tenon’s route did not consistently affect
the blood-retinal barrier permeability and that there was no diffusion of
the steroids into the eye in therapeutically meaningful concentrations,
despite accurate drug placement.
References
(1) AA Okada, T Wakabayashi, Y Morimura, S Kawahara, E Kojima, Y Asano and
T Hida. Trans-Tenon’s retrobulbar triamcinolone infusion for the treatment
of uveitis. Br J Ophthalmol 2003;87:968-971.
(2) Freeman WR, Green RL, Smith RE. Echographic localization of
corticosteroids after periocular injection. Am J Ophthalmol 1987 Mar;
15;103(3 Pt 1):281-8.
(3) Jennings T, Rusin MM, Tessler HH, Cunhavaz JG. Posterior sub-tenon’s
injections of corticosteroids in uveitis patients with cystoid macular
edema. Jpn J Ophthalmol 1988;32:385-391.
We write in reference to the letter by Galloway et al. "Macular
infarction after intravitreal amikacin: Mounting evidence against
amikacin".[1]
The authors report a single case of macular infarction in a patient
who had been given intravitreal amikacin for endophthalmitis. They cite
that single case plus some prior literature as reason to support a
change
in the choice of antibiotic fo...
We write in reference to the letter by Galloway et al. "Macular
infarction after intravitreal amikacin: Mounting evidence against
amikacin".[1]
The authors report a single case of macular infarction in a patient
who had been given intravitreal amikacin for endophthalmitis. They cite
that single case plus some prior literature as reason to support a
change
in the choice of antibiotic for intravitreal injection from the
treatment
guidelines based on the results of the Endophthalmitis Vitrectomy Study
(EVS).
While aminoglycoside induced retinal toxicity certainly can occur,
we
disagree with their statement that there is good evidence that
aminoglycosides should not be primary drugs of choice in this disease.
There are several theoretical and practical advantages of
aminoglycosides
over ceftazidime. Amikacin provides concentration dependent killing (so
that the higher concentration of drug the more rapid the kill) which is
not true for ceftazidime.
This is an important issue since high concentrations of drug are
administered by intravitreal injection, thus possibly allowing for more
rapid kill with amikacin. Amikacin is considered to be synergistic with
vancomycin for certain gram positive species, so its use provides
benefit
against gram positive organisms, not just for gram negatives. Gram
positive organisms make up the overwhelming majority of cases of
endophthalmitis. In addition, there has been a recent report that
ceftazidime may precipitate in the vitreous at normal body temperature,[2] possibly making it less available than one might wish in the
vitreous
cavity.
Finally, and very important, is the fact that amikacin has been
found
to be effective in a clinical trial but there is no such evidence yet
available on ceftazidime. The only apparent advantage to ceftazidime is
that it may be a somewhat safer drug in the sense that macular toxicity
has not been reported. Even so, the incidence of macular toxicity is
extremely rare (only 1 in 420 eyes in the EVS suffered macular toxicity
possibly from the drug). In a very severe disease such as
endophthalmitis
a risk this low is worth tolerating when there may be substantial
potential advantages.
References
(1) Galloway G, Ramsay A, Jordan K, et al, Macular infarction after
intravitreal Amikacin: mounting evidence against Amikacin. Br J
Ophthalmol
2002;86:359-360.
(2) Kwok, AK., M. Hui, et al. An in vitro study of ceft)azidime and
vancomycin concentrations in various fluid media: implications for use
in
treating endophthalmitis." Invest Ophthalmol Vis Sci 2002,43(4): 1182-8.
I read with great interest the article by Sitorus et al.[1] on the causes
of
blindness at a blind school in Indonesia. I would like to supplement and clarify certain points mentioned in the article.
It was sobering to note that Indonesia has the highest rate of
blindness (1.5%) among the Asian countries, much more than India (0.7%).
Incidentally, the similarities with the Indian scenario...
I read with great interest the article by Sitorus et al.[1] on the causes
of
blindness at a blind school in Indonesia. I would like to supplement and clarify certain points mentioned in the article.
It was sobering to note that Indonesia has the highest rate of
blindness (1.5%) among the Asian countries, much more than India (0.7%).
Incidentally, the similarities with the Indian scenario were striking.
The
predominance of hereditary and postnatal infectious eye diseases; a
pattern intermediate to that seen in developing and developed countries
and the high proportion of autosomal recessive disorders amongst the
genetic eye diseases due in turn to the high degree of consanguinity
have
been reported previously from India.[2,3]
However, there is an equally striking difference as well.
It was remarkable that the study found that the majority of the students in the blind school had vision that was mostly between hand movements
and
light perception only. In contrast, studies from the Indian subcontinent
have found a high percentage of patients with correctable defective
vision, despite the similar aetiologies of low vision.[4,5]
The study by Hornby et al in six blind schools in India,[4] found that
one
in seven children could read normal print with optical support, with
15.4%
of the children being able to read N10 point although they were studying
Braille! Similarly, treatable refractive error was found to account for
33.3% of childhood blindness in two large population based studies in a
southern Indian state.[5] Although definite conclusions cannot be drawn
from these two studies alone, this could reflect the lack of awareness
or
access to primary eye care for correction of even a simple refractive
error in India. Alternatively, it could mean that children with
uncorrected refractive errors and navigational vision were not admitted
to
the blind schools in Indonesia and were still at large in the community.
Thus, although the aetiologic causes are more or less similar, the
intervention programmes would have to be region-specific and quite
different for both the countries.
The authors have mentioned that all the cases of phthisis bulbi
were due to infection. A significant subset of these cases could be
secondary to uveitis or trauma, that are also quite common in childhood.
It might not be appropriate to attribute all the cases of phthisis bulbi to infection alone.
The article mentions the disturbing fact that blind children with
multiple handicaps were not accepted for admission in the blind schools
in
Indonesia. Similar admission criteria precluding admission of blind
children with mental retardation in blind schools in Ethiopia was
reported previously.[6] Such rules exist in India and China as well. In
contrast, the blind schools in the United Kingdom and the United states,
(where lesions of the central nervous system are the commonest cause of
childhood blindness)[7] allow admission of such children. Considering that
children with mental retardation could also be suffering from cortical
visual impairment (due to perinatal factors such as hypoxic ischaemic
encephalopathy), I wonder whether such regional differences in the
admission criteria of the blind schools could account for the high
prevalence of cortical blindness in the West as opposed to the
developing
countries! This is all the more plausible since much of the information
on
childhood blindness that we have today is based on studies on children
in
schools for the blind.[7]
References
(1) Sitorus RS, Preising M, Lorenz B. Causes of bindness at the "Wiyata
Guna" school for the blind, Indonesia. Br J Ophthalmol 2003;87:
1065-1068.
(2) Rahi JS, Sripathi S, Gilbert CE, Foster A. Childhood blindness in
India: causes in 1318 blind school students in nine states. Eye1995;9:
545
-50.
(3) Rahi JS, Sripathi S, Gilbert CE, Foster A. The importance of prenatal factors in childhood blindness in India. Dev Med Child Neurol
1997;39(7):
449-55.
(4) Hornby SJ, Adolph S, Gothwal VK, Gilbert CE, Dandona L, Foster A.
Evaluation of children in six blind schools of Andhra Pradesh. Indian J
Ophthalmol 2000;48(3): 195-200.
(5) Dandona R, Dandona L. Childhood blindness in India: a population
based perspective. Br J Ophthalmol 2003;87(3): 263-5.
(6) Kello A B, Gilbert C. Causes of severe visual impairment and
blindness
in children in schools for the blind in Ethiopia. Br J Ophthalmol 2003;
87: 526-530.
(7) Gilbert C, Foster A. Childhood blindness in the context of VISION
2020-
the right to sight. Bull World Health Organ 2001;79(3):227-32.
We read with interest Cohen and associates’ report on the onset of
Charles Bonnet syndrome (CBS) following photodynamic therapy (PDT) for
choroidal neovascularization (CNV).[1] An earlier study reported that 16.6%
of patients developed CBS following macular photocoagulation for CNV.[2]
Holroyd and co-workers reported a patient with sudden onset of visual
hallucinations after laser treatment, which cease...
We read with interest Cohen and associates’ report on the onset of
Charles Bonnet syndrome (CBS) following photodynamic therapy (PDT) for
choroidal neovascularization (CNV).[1] An earlier study reported that 16.6%
of patients developed CBS following macular photocoagulation for CNV.[2]
Holroyd and co-workers reported a patient with sudden onset of visual
hallucinations after laser treatment, which ceased after a second laser
treatment one year later.[3] Two other patients’ visual hallucinations
ceased acutely after laser therapy for macular degeneration.[4]
We recently reported a case of CBS following bilateral sequential
Argon-Nd:YAG laser peripheral iridotomies.[5] This case differs from the
others noted above in that the laser treatment involved the anterior
segment of the eye and was not specifically targeted on the retina
although it is possible that some laser energy may have been transmitted
to the posterior pole during the iridotomies. It is therefore interesting
to note that various ophthalmic laser procedures may precipitate as well
as terminate the symptoms of CBS.
Several different mechanisms may be involved in the pathogenesis of
CBS.[6,7] The sensory deprivation theory[8] may explain its onset following
certain ophthalmic laser procedures. An acute reduction in visual acuity
may occur following destruction of foveal tissue during macular
photocoagulation [2,3] and secondary to anterior segment inflammation and
corneal changes after laser peripheral iridotomy.[5] Cohen et al. suggested
that acute anatomical changes at the fovea following PDT could have
triggered visual hallucinations in some patients.[1] To explain cessation of
hallucinations after laser procedures, Holroyd et al. postulated that laser
photocoagulation may have destroyed the neurons causing abnormal sensory
signals, thereby terminating the hallucinations.[4]
Regardless of the mechanism resulting in hallucinations, it appears
that CBS is a possible sequelae of many ophthalmic laser procedures and
these symptoms can be quite distressful to some patients. It may be
useful to ask specifically for symptoms of CBS following laser procedures
as some patients who have been unwilling to discuss their symptoms have
subsequently expressed relief upon learning that CBS does not imply a
psychiatric illness.
References
(1) Cohen SY, Bulik A, Tadayoni R, et al. Visual hallucinations and
Charles Bonnet syndrome after photodynamic therapy for age related macular
degeneration. Br J Ophthalmol 2003;87:977-9.
(2) Cohen SY, Safran AB, Tadayoni R, et al. Visual hallucinations
immediately after macular photocoagulation. Am.J Ophthalmol. 2000;129:815-
6.
(3) Holroyd S, Rabins PV, Finkelstein D, et al. Visual hallucinations
in patients from an ophthalmology clinic and medical clinic population. J
Nerv.Ment.Dis. 1994;182:273-6.
(4)Holroyd S, Rabins PV. A three-year follow-up study of visual
hallucinations in patients with macular degeneration. J Nerv.Ment.Dis.
1996;184:188-9.
(5) Tan CSH, Yong VKY, KG Au Eong. Onset of Charles Bonnet Syndrome
(Formed Visual Hallucinations) Following Bilateral Laser Peripheral
Iridotomies. Eye, in press.
(6) Fernandez A, Lichtshein G, Vieweg WV. The Charles Bonnet
syndrome: a review. J Nerv.Ment.Dis. 1997;185:195-200.
(7) Menon GJ, Rahman I, Menon SJ, et al. Complex visual
hallucinations in the visually impaired: the Charles Bonnet Syndrome.
Surv.Ophthalmol 2003;48:58-72.
(8) Berrios GE, Brook P. The Charles Bonnet syndrome and the problem
of visual perceptual disorders in the elderly. Age Ageing 1982;11:17-23.
Dear Editor
I was delighted to read Dr Okada’s reply to my letter.[1] At the risk of transgressing from the point of the original article [2] that dealt with a novel technique to administer triamcinolone to a wide group of patients with uveitis, I would like to reply:
1. The WHO guidelines are indeed silent on the treatment of latent tuberculosis which can be defined as merely positive mantoux tests w...
Dear Editor
I read with great interest the article by Isenberg et al.[1] on "A double application approach to ophthalmia neonatorum prophylaxis." The authors deserve to be commended for their pioneering interest in childhood blindness. There are certain points that I would like to clarify and supplement with regard to their study.
1. The authors have mentioned that only babies born by a vagin...
Dear Editor
We thank Dr Doft, et al. for their useful and expert opinion. The choice of which agent to use to empirically treat gram-negative organisms implicated in endophthalmitis remains controversial. As amikacin has been proven to cause macular infarction, we feel one should look at viable alternatives. Ceftazidime is already in widespread use in the UK and appears not only to have an excellent safe...
Dear Editor
We read with interest the article by Joussen et al. on the long term results of retinectomy for the treatment of intractable glaucoma.[1] We congratulate the authors for studying this innovative method for the management of refractory glaucoma with a long follow-up of five years.
The high incidence of complications in the study however has aroused our concerns as only 15.9% of patients...
Dear Editor
Thanks to Dr Fan and coworkers for their letter and interests in our article.[1]
The conclusion drawn by us was that confocal microscopy was a rapid and sensitive diagnostic tool for both early diagnosis and non-invasive follow -up of fungal keratitis, not that it was a superior to culture and corneal biopsy staining techniques in the early stage of fungal keratitis. It is rapid compared to cultu...
Dear Editor
We read with great interest the article by G Prakash et al.[1]
We are trained as residents to overcome this problem by using simcoe cannula and performing manual irrigation and aspiration through the sideport for removal of subincisional cortex easily even in the presence of a small rhexis. We have found this to be a much safer technique than other methods such as using a J shaped cannula o...
Dear Editor
I thank Dr Okada et al for replying to my letter to the editor regarding their article "Trans-Tenon's retrobulbar triamcinolone infusion for the treatment of uveitis".[1] While speculating that the cause of the lack of therapeutic response to sub-tenon’s corticosteroids may be because of placement at a site relatively far from the target zone, I had quoted only the article by Freeman et al...
Dear Editor
We write in reference to the letter by Galloway et al. "Macular infarction after intravitreal amikacin: Mounting evidence against amikacin".[1]
The authors report a single case of macular infarction in a patient who had been given intravitreal amikacin for endophthalmitis. They cite that single case plus some prior literature as reason to support a change in the choice of antibiotic fo...
Dear Editor
I read with great interest the article by Sitorus et al.[1] on the causes of blindness at a blind school in Indonesia. I would like to supplement and clarify certain points mentioned in the article.
It was sobering to note that Indonesia has the highest rate of blindness (1.5%) among the Asian countries, much more than India (0.7%). Incidentally, the similarities with the Indian scenario...
Dear Editor
We read with interest Cohen and associates’ report on the onset of Charles Bonnet syndrome (CBS) following photodynamic therapy (PDT) for choroidal neovascularization (CNV).[1] An earlier study reported that 16.6% of patients developed CBS following macular photocoagulation for CNV.[2] Holroyd and co-workers reported a patient with sudden onset of visual hallucinations after laser treatment, which cease...
Pages