We welcome Loon SC et al's article [1]. Earlier, we published our
finding of the SARS CoV in specimens collected by the novel technique of
conjunctiva upper respiratory tract irrigation (CURTI), but not in paired
nose and throat swabs, very early in the course of the disease [2]. In
designing CURTI, we considered safety to medical personnel but also, in
finding a method that samples all three portal...
We welcome Loon SC et al's article [1]. Earlier, we published our
finding of the SARS CoV in specimens collected by the novel technique of
conjunctiva upper respiratory tract irrigation (CURTI), but not in paired
nose and throat swabs, very early in the course of the disease [2]. In
designing CURTI, we considered safety to medical personnel but also, in
finding a method that samples all three portals of entry for upper
respiratory viral pathogens ¡V the eyes, nose and mouth. Loon et al's
finding now complements our study by showing that SARS CoV indeed can be
found in tears.
While we agree with their conclusion that the ability to isolate the
virus early in the course is important, we do not feel that the eyes are
important organs that propagate the virus, other than to ophthalmologists
and to unwary close contacts. For instance, the eyes cannot generate
infectious aerosol. Rather, we feel that the eyes are important portals of
entry and have not been given sufficient attention - witness medical
personnel in full personal protection gears and N95 masks but without
watertight goggles, and sometimes without splashguards at all.
We also feel that employing the services of ophthalmologists for the
purpose of collecting tear specimens for the diagnosis of SARS is
difficult to achieve in most medical environments. On the other hand, our
method of CURTI is entirely self-help, deployable to quarantine locations,
and avoids unnecessary contact between an infectious source and
susceptible individuals.
The finding of SARS CoV in tear raises several additional questions:
1. How does the virus end up in the tear? Was it due to direct
inoculation at the time of infection to permissive conjunctival epithelial
cells, either by hands or aerosols, or was it the result of secretion from
a lacrimal gland infected hematogenously? The lacrimal glands are not very
different anatomically from the salivary glands. Yet saliva has been shown
to be a poor specimen for the laboratory diagnosis of SARS.[3]
2. Was there any evidence of conjunctivitis, lacrimitis, or evidence
of infection of the globe or nasolacrimal sac?
3. Is there any means or advantage in sampling the nasolacrimal sac,
to which the tear drains, and could the nasolacrimal duct system be itself
a hideout for the SARS CoV during the incubation period?
References
(1) Loon SC, Teoh SC, Oon LL, Se-Thoe SY, Ling AE, Leo YS, Leong HN.
The severe acute respiratory syndrome coronavirus in tears. Br J
Ophthalmol. 2004 Jul;88(7):861-3.
(2) Tong TR, Lam BH, Ng TK, Lai ST, Tong MK, Chau TN. Conjunctiva-
upper respiratory tract irrigation for early diagnosis of severe acute
respiratory syndrome. J Clin Microbiol. 2003 Nov;41(11):5352.
(3) Drosten C, Chiu LL, Panning M, Leong HN, Preiser W, Tam JS,
Gunther S, Kramme S, Emmerich P, Ng WL, Schmitz H, Koay ES. Evaluation of
Advanced Reverse Transcription-PCR Assays and an Alternative PCR Target
Region for Detection of Severe Acute Respiratory Syndrome-Associated
Coronavirus. J Clin Microbiol. 2004 May;42(5):2043-7.
We read with great interest the case report of severe vision loss by
ostrich pecking trauma and would like to bring readers attention to a case
we recently reported about an adult farm worker who lost his vision due to
an ostrich attack [1]. In our case, a 34-year-old male was attacked by
the giant bird with consequent severe pain and immediate loss of vision to
no light perception. On examination, pati...
We read with great interest the case report of severe vision loss by
ostrich pecking trauma and would like to bring readers attention to a case
we recently reported about an adult farm worker who lost his vision due to
an ostrich attack [1]. In our case, a 34-year-old male was attacked by
the giant bird with consequent severe pain and immediate loss of vision to
no light perception. On examination, patient’s right eye had significant
proptosis with severe limitations of the globe in all directions and
irregular full-thickness lacerations of the skin. Exploration of the wound
revealed two fragments of bony-like tissue but no fractures. Ultrasound
examination and CT-scan of the orbits revealed a disorganized right globe
with multiple scleral ruptures without any bony fractures. Microscopic
examination of bony fragments was consistent with avian rostrum.
Human eye injuries caused by pecking of birds are uncommon and are
usually labeled as humorous or incidental, and, consequently, most go
unreported. Serious injuries to humans caused by birds have been sparsely
reported in the English literature. In the non-English literature, Kuhl
reviewed a series of 14 patients with severe eye injuries from 1875
through 1970 caused by birds [2]. All were penetrating ocular injuries,
and some caused permanent visual injuries and/or blindness.
In general, birds are viewed as presenting less of a danger because
of the assumption that the bird will take flight if frightened. On the
contrary, some birds show aggressive behaviors related to territoriality
or breeding. The male ostrich (a flightless bird) is known to establish
territory, display aggressive territorial behavior, and may attack
potential predators [3]. These two reports of an ostrich attack causing
permanent visual loss in adult humans are first in the ophthalmic
literature and emphasize the potential for serious ocular injuries from
birds. People living in rural areas and those who work or plan to visit
farms should be aware that territorial behavior of many domestic animals
and birds may be a potential risk factor.
Imtiaz A. Chaudhry, M.D., Ph.D, FACS
Abdulrahman M. Al-Sharif, M.D
Mohammad Hamdi, M.D
King Khaled Eye Specialist Hospital
PO Box 7191
Riyadh 11462, Saudi Arabia
Tele: 966 (1) 482 1234 ext: 3771
e-mail: orbitdr@hotmail.com
References
(1) Chaudhry IA, Al-Sharif AM, Hamdi M. Severe ocular and periocular
injuries caused by an ostrich. Ophthal Plast Reconstr Surg. 2003;19:246-7.
(2) Kuhl W. Augen verletzungen durch Vogel [Eye injuries caused by
birds].Klin Monatsbl Augenheilkd. 1970;157:810-5.
(3) Deeming DC, Bubier NE. Behavior in natural and captive
environments. In: Deeming DC, ed. The Ostrich: Biology, Production and
Health. Cambridge: University Press; 1999:83-103.
I read with interest the article entitled
Deposition of silicone oil droplets in the residual
anterior lens capsule after vitrectomy and lensectomy in
rabbits by Miyamoto et al [1]. Numerous studies have
examined the interrelationship between silicone oil and
various ocular structures, such as the retina, iris, or
anterior chamber. However, the silicone oil itself was
never evident in these studies,...
I read with interest the article entitled
Deposition of silicone oil droplets in the residual
anterior lens capsule after vitrectomy and lensectomy in
rabbits by Miyamoto et al [1]. Numerous studies have
examined the interrelationship between silicone oil and
various ocular structures, such as the retina, iris, or
anterior chamber. However, the silicone oil itself was
never evident in these studies, but rather small vacuoles
suspected to be ghosts of the incorporated silicone oil
were apparent. Nevertheless, the vacuoles also could have
been artifacts [2] because silicone, which is solubilized
in the organic solvents during the preparation [3], is
never detected. We previously demonstrated silicone oil
emulsion in the rabbit retina using phthalocyanine blue as
a marker [4]. This compound contains a copper molecule that
imparts a blue color and remains in the tissue after the
silicone oil is washed out and enables visualization of the
silicone emulsion in the trabecular meshwork at the light
and electron microscopic levels. When we injected a
suspension of the dye into the anterior chamber, the dye
filled the small vacuoles within the cells. In contrast,
when silicone droplets containing the dye were injected
into the chamber, the blue dye formed clusters in small
cellular vacuoles (light microscopy) and touched the
limiting membranes of the vacuoles (electron microscopy).
The silicone droplets were washed out by the organic
solvents used to prepare the specimens, and since the dye
was insoluble in the organic solvent, it probably
precipitated around the vacuoles [5]. However, Figure 5 of
this article did not show any limiting membranes or the low
magnification of this figure precluded their
identification. In addition, energy dispersive X-ray
analysis is also a useful method to detect silicone oil in
tissues [6].
The authors injected silicone oil that was not emulsified
into the vitreous cavity after vitrectomy. However,
silicone oil that is not emulsified has a large surface
area and high interfacial surface tension and is not
incorporated into the tissues. The authors did not show by
gross examination whether silicone oil became emulsified
during the experiment. They should discuss why they could
see residual silicone oil in the rest of the anterior
capsule. The readers were not able to obtain information
about silicone oil structure. Although the authors
described emulsification of silicone oil related to
protein, many factors are involved in this process.
Contamination of low-molecular-weight siloxanes may enhance
silicone oil emulsification.
In the Discussion, the authors state: 'It is likely that
lens epithelial cells attaching to oil droplets might be
stimulated to express many wound healing related molecules
including extracellular matrix components'. This is
speculation. The central area of the posterior surface of
the rest of the anterior capsule is covered with
accumulated fibrous extracellular matrix in Figures 2B and
4B. However, there were no differences in the expression of
collagen types I, III, V and cellular fibronectin by
immunohistochemistry. The authors did not provide these
data in the text. If this information is related to their
hypothesis, they should demonstrate differences by
providing immunohistochemical data.
References
(1) Miyamoto T, Saika S, Yamanaka A, Okada Y, Ohnishi Y.
Deposition of silicone oil droplets in the residual
anterior lens capsule after vitrectomy and lensectomy in
rabbits. Br J Ophthalmol 2004;88:703-7.
(2) Ober RR, Blanks JC, Ogden TE, Pickford M, Minckler DS,
Ryan SJ. Experimental retinal tolerance to liquid silicone.
Retina 1983;3:77-85.
(3) Mukai N, Lee PF, Schepens CL. Intravitreous injection of
silicone: an experimental study. II. Histochemistry and
electron microscopy. Ann Ophthalmol 1972;4:273-87.
(4) Ohira A, Wilson CA, de Juan E Jr, Murata Y, Soji T,
Oshima K. Experimental retinal tolerance to emulsified
silicone oil. Retina 1991;11:259-65.
(5) Ohira A, Chihara E, Soji T. Egress route of emulsified
20 centistokes silicone oil from anterior chamber of
rabbit. Curr Eye Res 1994;13:489-95.
(6) Saitoh A, Taniguchi H, Gong H, Ohira A, Amemiya T, Baba
T. Long-term effect on optic nerve of silicone oil
tamponade in rabbits: histological and EDXA findings. Eye
2002;16:171-6.
We read with interest the letter of Dr J Colin with regard to their
observations on dendritic ulcerations of conjunctiva. We are grateful to
the authors for directing our attention to the earlier published report.
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.
I read with great interest the letter by Doft et al [1] suggesting amikacin
to be a better alternative to ceftazidime, in response to the article by
Galloway et al [2] that suggested the converse. I would like to suggest that
ciprofloxacin is a better alternative to both these drugs. There are
certain points that I would like to mention to support my statement.
I read with great interest the letter by Doft et al [1] suggesting amikacin
to be a better alternative to ceftazidime, in response to the article by
Galloway et al [2] that suggested the converse. I would like to suggest that
ciprofloxacin is a better alternative to both these drugs. There are
certain points that I would like to mention to support my statement.
1. It has been shown that vancomycin and ceftazidime are incompatible
upon mixing, with precipitate formation [3]. In addition, Kwok et al have
suggested ceftazidime to be relatively ineffective owing to its higher
rate of precipitation in the vitreous at body temperature resulting in a
free antibiotic concentration much lesser than the MIC90 of the
organisms [4]. Interestingly, in the study, ceftazidime precipitated to a
significant extent, especially when prepared in balanced salt solution
plus (BSS Plus) than in normal saline (NS) with up to 88% loss in
concentrations of the measurable free antibiotics. Such a low antibiotic
concentration would be inadequate for the treatment of a potentially
blinding disease like infective endophthalmitis.
Hui et al, in an elegant study measured the concentrations of vancomycin
and ciprofloxacin in an equilibrium dialysis chamber by high performance
liquid chromatography and fluorescence polarisation immunoassay [5]. They
did note that ciprofloxacin precipitates in vitreous, but to a much lesser
extent than ceftazidime and significantly, the remaining ciprofloxacin
concentration was many times above the MIC90 of the drug against the
common Gram negative bacteria encountered. This suggests that the problem
of precipitataion might not be so important in the usage of intravitreal
ciprofloxacin. The precipitation of ciprofloxacin was also found to be
independent of the medium, which means that there is no need to avoid the
use of BSS Plus during preparation of the ciprofloxacin for intravitreal
injection nor during intraocular surgery.
2. Various studies have shown the efficacy of ciprofloxacin. Benz et al
have shown that 92% of Gram negative organisms in culture proved
endophthalmitis were susceptible to ciprofloxacin [6]. In the Indian scenario
too ciprofloxacin is considered to be a very dependable drug. In fact,
88.4% of even the gram-positive organisms in the series of Anand et al [7]
were sensitive to ciprofloxacin! This is a significantly lower rate of
resistance of gram positive organisms to ciprofloxacin than that found in
the EVS. The series of posttraumatic endophthalmitis over a period of two
years from our institute also shows 26 of the 39 isolates to be sensitive
to ciprofloxacin and a hitherto unreported poor rate of susceptibility to
ceftazidime (4 out of the 39 isolates); (unpublished data).
3. The intravitreal combination of choice for the initial empiric
treatment of endophthalmitis could be vancomycin and ciprofloxacin! A
certain amount of synergy could be expected with this combination, with
vancomycin inhibiting the cell wall synthesis of the bacteria allowing
ciprofloxacin to penetrate into the cell and inhibiting the DNA
supercoiling. This synergy and the resultant greater bactericidal activity
would be all the more important considering that there is no assistance
from the body’s immune system in combating the intraocular infection.
Although it has been proved to be non-toxic in animal models [8] this
substitution of ceftazidime with ciprofloxacin of course, would
necessitate further studies on the safety profile of intravitreal
ciprofloxacin.
Vasumathy Vedantham MS, DNB, FRCS.
Correspondence to Dr.Vasumathy Vedantham, Consultant, Retina-Vitreous
service, Aravind Eye hospital & PG Institute of Ophthalmology, 1, Anna
Nagar, Madurai, Tamil Nadu, India-625020.
E-Mail: drvasumathy@yahoo.com.
References
(1) Doft BH, M Barza. Macular infarction after intravitreal amikacin. Br J
Ophthalmol 2004;88: 850.
(2) Galloway G, Ramsay A, Jordan K, Vivian A. Macular infarction after
intravitreal amikacin: mounting evidence against amikacin. Br J Ophthalmol
2002;86: 359-360.
(3) Lifshitz T, Lapid-Gortzak R, Finkelman Y, Klemperer I. Vancomycin and
ceftazidime incompatibility upon intravitreal injection. Br J Ophthalmol
2000;84:117–118.
(4) Kwok AKH, Hui M, Pang CP, Chan RCY, Cheung SW, Yip CMS, Lam DSC, Cheng
AFB. An in vitro Study of ceftazidime and vancomycin concentrations in
various fluid media: implications for use in treating endophthalmitis.
Invest Ophthalmol Vis Sci 2002;43: 1182–8.
(5) Hui M, Kwok AKH, Pang CP, Cheung SW, Chan RCY, Lam DSC, Cheng AFB. An
in vitro study on the compatibility and precipitation of a combination of
ciprofloxacin and vancomycin in human vitreous. Br J Ophthalmol 2004;88:
218-222.
(6) Benz MS, Scott IU, Flynn HW, et al. In vitro susceptibilities to
antimicrobials of pathogens isolated from the vitreous cavity of patients
with endophthalmitis. Invest Ophthalmol Vis Sci 2002;43:E-Abstract 4428.
(7) Anand AR, Therese KL, Madhavan HN. Spectrum of aetiological agents of
postoperative endophthalmitis and antibiotic susceptibility of bacterial
isolates. Indian J Ophthalmol 2000;48: 123-128.
(8) Hainsworth DP, Conklin JD, Bierly JR, Ax D, Ashton P. Intravitreal
delivery of ciprofloxacin. J Ocul Pharmacol Ther1996;12: 183–91.
Marsh and colleagues [1] raise the spectre of a possible association
between
the use of sildenafil and the development of retinopathy of prematurity
(ROP)
in a 26-week gestation baby with pulmonary hypertension. We are
concerned
that this report offers no real evidence for its claims and that a
potentially
lifesaving agent is being unfairly maligned.
Marsh and colleagues [1] raise the spectre of a possible association
between
the use of sildenafil and the development of retinopathy of prematurity
(ROP)
in a 26-week gestation baby with pulmonary hypertension. We are
concerned
that this report offers no real evidence for its claims and that a
potentially
lifesaving agent is being unfairly maligned.
The report describes the use of intravenous sildenafil of
unspecified
dose for
16 days in a 525 g preterm with a very difficult intensive care course.
The
management included a litany of recognised causes of ROP, including
extreme prematurity, >6 weeks mechanical ventilation with 80-100%
oxygen, and bacterial and fungal infections.
Despite this, Marsh et al chose to incriminate sildenafil as the
causal agent.
The suggestion is even more perplexing as the baby had already received
inhaled nitric oxide at high levels (40ppm for 2-3 weeks) prior to the
sildenafil; both are vasodilators and have the same mechanism of action.
The authors make the
further statement that they observed a recent increase in
treatable ROP in their unit, coinciding with the use of sildenafil.
Where
is their
evidence?
As far as we are aware there is no evidence in the literature that
sildenafil has
any significant effect on either retinal or choroidal blood vessels.
Pache et al
reported [2] that in adults, siledenafil induced a 5.8% dilatation of
retinal
vessels but this was not confirmed by Grunwald et al [3] on either retinal
or
choroidal circulations [4]. To date there is no data on the effect of
sildenafil on
the developing ocular circulations.
We entirely agree that vigilant monitoring and responsible
reporting
of side
effects is mandatory for any new drug application. To our knowledge the
only available intravenous sildenafil is
being
released on a named patient basis in a prospective study in neonates.
How did the authors obtain and administer the drug in neonates?
Sildenafil and inhaled nitric oxide are experimental therapies within
the
preterm population and as clinicians we have a responsibility to ensure
that
they are used as part of prospective randomised controlled trials with
the
appropriate short and long term follow up. Although being well
intentioned,
such unconvincing reports may impede the use of agents which might have
an important future role in the management of primary pulmonary
hypertension of the newborn.
Conflict of interest
The authors have acted in an independent consultant capacity (CMP, AJP,
ARF)
and are in receipt of financial support in the form of a research grant
(CMP,
AJP) from the manufacturers of sildenafil, Pfizer Ltd.
Pierce CM, Consultant Paediatric Intenisivist(1)Petros AJ, Consultant Paediatric Intenisivist(1)
Fielder AR, Professor of Ophthalmology(2)
1.Neonatal Intensive Care Unit
Great Ormond Street Hospital
London WC1N 3JH
2. Department of Visual Neuroscience
Imperial College London
Room 9L02, Charing Cross Campus
St Dunstan's Road
London, W6 8RP
(1) Marsh CS. Marden B, Newsom R. Severe retinopathy of prematurity
(ROP) in a premature baby treated with sildenafil acaetate (Viagra) for
pulmonary hypertension. Br J Ophthalmol 2004; 84: 306-307
(2) Pache M, Meyer P, Prünte C, Orgül S, Nuttli I, Flammer J.
Sildenafil
induces retinal vasodilatation in healthy subjects. Br J Ophthalmol
2002;
86:
156-158
(3) Grunwald JE, Siu KK, Jacob SS, Dupont J. Effect of sildenafil
(Viagra) on
the ocular circulation. Am J Ophthalmol 2001; 131: 751-755
(4) Grunwald JE, Metelisina T, Grunwald L. Effect of sildenafil
(Viagra) on
retinal blood vessel diameter. Am J Ophthalmol 2002; 133: 809-812
pede the use of agents which might have an important future role in the
management of primary pulmonary hypertension of the newborn.
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
I read with great interest the article of Koranyi and coworkers, who
evaluated a new technique for pterygium surgery using a fibrin tissue
adhesive (Tisseel Duo Quick)[1]. In their randomized trial the authors
concluded that using the glue instead of sutures caused less
postoperative pain and shortened the surgical time. Nevertheless, the
timing of the randomization is not clearly stated in their re...
I read with great interest the article of Koranyi and coworkers, who
evaluated a new technique for pterygium surgery using a fibrin tissue
adhesive (Tisseel Duo Quick)[1]. In their randomized trial the authors
concluded that using the glue instead of sutures caused less
postoperative pain and shortened the surgical time. Nevertheless, the
timing of the randomization is not clearly stated in their report.
Whether or not the surgeon knew the patient’s group (sutures or
fibrin glue) at the time of pterygium removal and conjunctival graft
harvesting may have influenced the extent of the removal and the size of
the graft. Therefore the differences in postoperative pain and/or
recurrence could be related to those initial steps and not only to the
final step, as the authors suggest. Ideally, the surgeon should be
informed if the conjunctival graft should be sutured or glued after
harvesting it.
Additionally, in their discussion the authors did not mention the
risk of infection when using fibrin glue. Some viruses, such as parvovirus
B19 (HPV B19) are particularly difficult to remove or inactivate, and
human infection has been reported after the use of fibrin glue [2]. In
thoracic surgery, epidemiologic evidence suggest that more than 20%
uninfected persons were subsequently infected with HPV B19 by use of
fibrin during the procedure [3]. Prions are also of concern. The direct
application of any of the apparently effective methods of prion
decontamination to plasma products is inappropriate because they are harsh
and denaturing [4]. Although the risks for both diseases are minimal, the
authors should have addressed this issue in their discussion.
References
(1). Koranyi G, Seregard S, Kopp. Cut and paste: a no suture, small
incision approach to pterygium surgery. Br J Ophthalmol 2004; 89:911-914
(2). Hino M, Ishiko O, Honda K-I, et al. Transmission of symptomatic
parvovirus B19 infection by fibrin sealant used during surgery. Br J
Haematol 2000;108:194-5
(3). Kawamura M, Sawafuji M, Watanabe M, et al. Frequency of
transmission of human parvovirus B19 infection by fibrin sealant used
during thoracic surgery. Ann Thorac Surg 2002;73:1098-100
(4). Taylor DM. Inactivation of TSE agents: safety of blood and blood-
derived products. Transfus Clin Biol 2003;10:23-5
We read with keen interest the article by CMG Cheung, OM Durrani and
PI
Murray on the safety of anterior chamber paracentesis in patients with
uveitis.[1]
We appreciate their efforts to describe a method that can be easily and
safely
performed on an out-patient basis.
Although the authors evaluated the safety of AC paracentesis
technique, the
volume of aqueous that can be safely collect...
We read with keen interest the article by CMG Cheung, OM Durrani and
PI
Murray on the safety of anterior chamber paracentesis in patients with
uveitis.[1]
We appreciate their efforts to describe a method that can be easily and
safely
performed on an out-patient basis.
Although the authors evaluated the safety of AC paracentesis
technique, the
volume of aqueous that can be safely collected was not addressed. Studies
have shown that compared to Caucasian and Black counterparts, the anterior
chamber angles of older Chinese are significantly narrower [2,3] and the iris joins the scleral wall more anteriorly.[4] Therefore, since a vast majority
of the
patients seen at our center are Asians, withdrawing 0.2 cc of aqueous may
not only be technically difficult but unsafe as well.
In addition, excessive withdrawal of aqueous may induce hypotony with
resultant hyphema. The latter complication occurred in 2 out of the 34
eyes
which underwent AC paracentesis at the Singapore National Eye Centre from
the year 2003 up to this writing. Hyphema, which has been found to occur
spontaneously in anterior uveitidies including herpetic iritis,[5] was
also
encountered post AC paracentesis in an eye with herpetic iritis in another
study.[6] Blood in the sample may be a source of contamination which
occurred in one of our specimens, requiring a repeat of the procedure;
this
time, withdrawing a smaller volume. The information regarding sample
volume recommendations would be of great clinical value not just to the
Uveitis specialist but to any ophthalmologist who performs the procedure
regardless of indication.
At our center, we utilize a similar method under slit lamp guidance
during
which patients experience very minimal discomfort. However, several
differences in technique are worth noting. 1. To prevent infection,
sterile
gloves are used. The surgeon also wears a surgical mask during the
procedure. 2. Eyelids are retracted using a lid speculum. 3. A gauge 30
instead of a gauge 27 needle is used. We note less resistance upon
corneal
penetration. 4. The corneal limbus is penetrated below the horizontal
meridian and aimed towards the 6 o’clock position to avoid lens puncture. 5.
We aspirate a 0.1 to 0.2 cc sample which is submitted for PCR and
intraocular
antibody analysis. If warranted, samples are submitted for additional
studies
such as fluid cytology or cultures. We stop aspirating before 0.2 cc is
withdrawn if we see the iris-lens diaphragm bowing anteriorly or corneal
folds appearing. Aspiration is preferred to passive withdrawal as this
procedure is less likely to be associated with aspiration of blood and is
also
comfortable for the patient. 6. A tuberculin syringe is managed single-
handedly by the surgeon. It is held between the thumb and middle fingers,
with the index finger along the rod adjacent to the flat end of the
plunger. 7. We instruct the patient to fixate on the surgeon’s ear opposite the eye
being
examined instead of stabilizing the globe with a pair of forceps.
Nevertheless, we commend the authors for emphasizing the value of a
seemingly simple and commonly performed procedure which greatly affects
the diagnosis and management of ocular pathologies.
References
1. C M G Cheung, O M Durrani, and P I Murray
The safety of anterior chamber paracentesis in patients with uveitis
Br J Ophthalmol 2004; 88: 582-583.
2. NG Congdon, PJ Foster, S Wamsley, J Gutmark, SK Seah, GJ Johnson
and AT
Broman. Biometric gonioscopy and the effects of age, race and sex on the
anterior chamber angle. Br J Ophthalmol 2002; 86: 18-22.
3. TY Wong, PJ Foster, TP Ng, JM Tielsch, GJ Johnson, SK Seah.
Variations in
ocular biometry in an adult Chinese population in Singapore: the Tanjong
Pagar Survey. Invest Ophthalmol Vis Sci 2001Jan; 42 (1): 73-80.
4. Y Oh, S Minelli, G Spaeth and W Steinman. The anterior chamber
angle is
different in different racial groups: a gonioscopic study. Eye 1994; 8: 104-108.
5. D Fong and M Raizman. Spontaneous hyphaema associated with
anterior
uveitis. Br J Ophthalmol 1993; 7: 635-638.
6. A Van der Lelij and A Rothova. Diagnostic anterior chamber
paracentesis
in uveitis: a safe procedure? Br J Ophthalmol 1997; 81: 976-979.
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Dear Editor
We read with keen interest the article by CMG Cheung, OM Durrani and PI Murray on the safety of anterior chamber paracentesis in patients with uveitis.[1] We appreciate their efforts to describe a method that can be easily and safely performed on an out-patient basis.
Although the authors evaluated the safety of AC paracentesis technique, the volume of aqueous that can be safely collect...
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