We read with interest the remarks of Crowston et al. [1] on our
article entitled "Value of two mortality assessment techniques for organ
cultured corneal endothelium: trypan blue versus TUNEL technique".[2] We
showed that the TUNEL technique revealed a far higher percentage of
endothelial cells (ECs) irreversibly engaged in a cell death process than
that obtained by trypan blue staining.
We read with interest the remarks of Crowston et al. [1] on our
article entitled "Value of two mortality assessment techniques for organ
cultured corneal endothelium: trypan blue versus TUNEL technique".[2] We
showed that the TUNEL technique revealed a far higher percentage of
endothelial cells (ECs) irreversibly engaged in a cell death process than
that obtained by trypan blue staining.
The two techniques were performed sequentially: after observation of
trypan blue staining, corneas were immediately fixed in formaldehyde for
TUNEL. Crowston et al. suggest that the trypan blue itself and/or the time
spent outside the organ-culture medium before fixing in formaldehyde may
have caused an artefactual increase in the percentage of TUNEL-positive
ECs. Two arguments counter this remark:
1. The trypan blue staining procedure is identical to that used in all
European cornea banks that use organ culture during endothelial
examination(s) of grafts. Neither the low concentration of trypan blue
(0.4%) nor the short exposure time (about 1 minute) nor the short
incubation in the presence of 0.9% NaCl has ever been incriminated in ECs
over-mortality in routine practice.[3] Moreover, the innocuity of
injections of trypan blue into the anterior chamber, a common feature
during cataract surgery, has been well demonstrated.[4]
2. The time spent outside the organ-culture medium before fixing in
formaldehyde, a period required for vital staining and microscopic
examination of the endothelium, lasts only a few minutes. The cornea
remains under the microscope for about one minute only, the time needed
for image acquisition. Such rapidity is possible by using a prototype
automatic analyser of the endothelium, which we developed and have
recently published.[5] This is very probably insufficient time for DNA
fragmentation to occur in the proportion we observed. Moreover, the fixing
of the endothelial layer in 10% formaldehyde is immediate, and prevents
any continuation of fragmentation phenomena. On balance, it is highly
unlikely that the succession of markings is responsible for the
discrepancy between the positivity percentages of the two techniques. In
addition, we chose not to perform the two techniques simultaneously on
paired corneas or on the halves of one cornea because we wanted to
superimpose the two stains on the same cornea and thus obtain a double
cell staining.
The second remark by Crowston et al. is particularly interesting. We
too were surprised by the high percentage of TUNEL-positive ECs (mean
12.7%, SD 16.4). This may imply that all the cells died within 8 days,
which was evidently not the case. We believe this apparent contradiction
can be explained by the following theory. The TUNEL staining is positive
during a relatively long window (24-48 hours [6]). The TUNEL index,
measured at a given moment, provides a global view of all the cells with
fragmented DNA. However, the DNA fragmentation may be at different stages,
and the cells very likely spread according to a Gaussian distribution.
Therefore the cells, which are TUNEL-positive at a given moment, will not
all die instantaneously and simultaneously. Only the cells furthest to the
right on the curve will die in the very short term, and it is probably
these that are liable to be revealed by trypan blue. If it were possible
to perform TUNEL on two consecutive days, the percentage of positive cells
revealed would probably be very similar, but a large majority of the
positive cells recorded on the second day would have already been counted
on day one... It is, however, undeniable that the cells TUNEL-positive at a
given moment will all die eventually. In other words, we believe that, at
the end of storage, corneas contain a number of ECs engaged in an
irreversible cell-death process far more extensive than the highly
unreliable trypan blue staining technique suggests.
References
(1) Crowston JG, Healey PR, Maloof A, et al . Quantifying corneal
endothelial cell death. Br J Ophthalmol 2002;86:1068.
(2) Gain P, Thuret G, Chiquet C, et al . Value of two mortality assessment
techniques for organ cultured corneal endothelium: trypan blue versus
TUNEL technique. Br J Ophthalmol 2002;86:306-10.
(3) Sperling S. Evaluation of the endothelium of human donor corneas by
induced dilation of intercellular spaces and trypan blue. Graefes Arch
Clin Exp Ophthalmol 1986;224:428-34.
(4) Norn MS. Per operative trypan blue vital staining of corneal
endothelium. Eight years' follow up. Acta Ophthalmol 1980;58:550-5.
(5) Gain P, Thuret G, Kodjikian L, et al. Automated tri-image analysis of
stored corneal endothelium. Br J Ophthalmol 2002;86:801-8.
(6) Mesner PW, Epting CL, Hegarty JL, et al. A timetable of events during
programmed cell death induced by trophic factor withdrawal from neuronal
PC12 cells. J Neurosci 1995;15:7357-66.
We read with interest the article by Elder and Suter about what
patients would like to know before having cataract surgery.[1] We
congratulate the authors on investigating an area that has obviously been
overlooked in ophthalmology. However we feel they failed to recognise some
unique aspects of our specialty and also think that the nature of their
study limits its practical application.
We read with interest the article by Elder and Suter about what
patients would like to know before having cataract surgery.[1] We
congratulate the authors on investigating an area that has obviously been
overlooked in ophthalmology. However we feel they failed to recognise some
unique aspects of our specialty and also think that the nature of their
study limits its practical application.
Firstly, one area that we feel is all too often left out of
discussions with patients prior to cataract surgery is the intended
refraction. The fact that the authors did not ask if patients would like
to be informed of this supports our suspicions. Many patients may not even
know that the surgeon can choose their focusing distance. Contact lens
wearers with a unilateral cataract may like to decide if the refractive
status of both eyes should remain the same or if the operated eye should
be emmetropic so that they only have to wear one contact lens. Some
patients may be interested in monovision, which has been highly successful
in self-selected patients [2] and is easily remedied with spectacles if
patients cannot tolerate it. Unlike many other areas of surgery, cataract
surgery has an additional functional and cosmetic side to it that we feel
patients need to have some awareness of before they can give their
informed consent to the operation.
The authors chose to analyse differences between male and female
patients. The purpose of doing this was not given in the aims, and we fail
to see any useful application of this information. Would it not have been
of more use to analyse the views of one-eyed patients who are putting all
their good vision on the line? It would seem sensible to provide
information at a level that satisfies those patients that have the most to
lose.
We also feel that the very nature of their study makes it difficult
to draw conclusions. Are patients indeed aware of just how many different
complications there are that have a 1 in 10,000 chance of occuring? Are
they really interested in the details of expulsive choroidal haemorrhage,
uveitis-glaucoma-hyphaema syndrome, or prolonged hypotony due to an
inadvertent persistant filtering bleb? Would they want to know about a
risk if it is less than background rates of visual loss? We currently give
patients an information leaflet that includes an estimate of the chance of
visual loss then broadly explains the types of complications that can
occur. We suspect that were we to produce written information detailing
all complications that occur with a frequency of 1 in 10,000 that many
patients, if asked, would prefer our original leaflet. As such, and until
a well thought out study is done that shows otherwise, we will continue to
provide this same amount of risk information to patients.
References
1. Elder MJ, Suter A. What patients want to know before they have cataract
surgery. Br J Ophthalmol 2004;88:331-2.
2. Greenbaum S. Monovision pseudophakia. J Cataract Refract Surg
2002;28:1439-43.
We read
with interest the paper published by Boschi, et. al.[1]
in which immunohistochemistry was performed on orbital tissues from
patients with thyroid associated ophthalmopathy (TAO) and compared to
non...
We read
with interest the paper published by Boschi, et. al.[1]
in which immunohistochemistry was performed on orbital tissues from
patients with thyroid associated ophthalmopathy (TAO) and compared to
non-diseased orbital tissue.
Our
laboratory recently reported positive TSH receptor staining within
normal human muscle fibres, using one of the same antibodies (3G4) as
Boschi et. al., (supplied by Costagliola) and a commercial antibody
(3B12) [2].
Our
findings differ from Boschi et. al.’s as no staining of the
muscle fibres was visible in their experience.
Assessing
the techniques used gave some possibilities as to why our findings
differ. Our paraffin-embedded tissues were subjected to a proteolytic
antigen retrieval step, as commonly used in avidin-biotin
staining.[3]
The reason for this is that formalin used in fixation is notorious
for altering protein immunoreactivity, and hence masking protein
expression.[4][5]
Moreover,
the amplification immunohistochemistry kit used in our experiments is
possibly more sensitive than conventional immunohistochemistry used
in the experiments of Boschi, et. al.[6]
We do not
dispute the finding that TSHR expression is elevated in orbital
connective tissue of diseased patients. Combined with our findings,
Boschi et. al.’s paper also suggests that expression of TSH-R
on normal muscle fibres is lower than in the connective tissue of
diseased patients. Boschi et. al. has successfully produced more
evidence that connective tissues in the orbit are active in TAO
affected patients, however the potential role of the extraocular
muscle in the pathogenesis of TAO should also be considered.
Yours
sincerely,
Steven J.
Kloprogge and Albert G. Frauman
References
1
Boschi A, Daumerie C, Spiritus M, et al. Quantification of cells
expressing the thyrotropin receptor in extraocular muscles in
thyroid associated orbitopathy. Br J Ophthalmol 2005;89(6):724-9.
2
Kloprogge SJ, Busuttil BE, Frauman AG. TSH receptor protein is
selectively expressed in normal human extraocular muscle. Muscle
Nerve. 2005;32(1):95-8.
3
Thompson LD, Miettinen M, Wenig BM. Sinonasal-type
hemangiopericytoma: a clinicopathologic and immunophenotypic
analysis of 104 cases showing perivascular myoid differentiation. Am
J Surg Pathol. 2003;27(6):737-49.
4
Fox CH, Johnson FB, Whiting J, et. al. Formaldehyde fixation. J
Histochem Cytochem 1985;33(8):845-53.
5
Puchtler H, Meloan SN. On the chemistry of formaldehyde fixation and
its effects on immunohistochemical reactions. Histochemistry
1985;82(3):201-4.
6Erber
WN, Willis JI, Hoffman GJ. An enhanced immunocytochemical method for
staining bone marrow trephine sections. J Clin Pathol.
1997;50(5):389-93.
We read the article '3D printed reproductions of orbital dissections:
a novel mode of visualising anatomy for trainees in ophthalmology or
optometry' by Adams JW. et al with great interest. The authors have
successfully identified the need for experience handling and navigating
through anatomical material to understand clinical ophthalmology.
Furthermore, they have brilliantly created a means for th...
We read the article '3D printed reproductions of orbital dissections:
a novel mode of visualising anatomy for trainees in ophthalmology or
optometry' by Adams JW. et al with great interest. The authors have
successfully identified the need for experience handling and navigating
through anatomical material to understand clinical ophthalmology.
Furthermore, they have brilliantly created a means for this teaching to
occur due to the difficulties obtaining cadaveric specimens, and the
similar issues and expense of using plastinated models.
We were particularly interested in the preparation of the orbital
dissections, and the choice of views to optimise the teaching value of the
prosections. In the paper, it is stated quite rightly that 'it is
essential to optimise the number of features displayed' (1). Given the
authors' expertise in recreating the best from the cadaveric specimens to
generate models, we would like the authors' opinion on how best to conduct
an ophthalmic anatomy teaching session for students using approximately
ten cadaveric heads which we will be running next year. What do the
authors think would be the most important teaching aims, and how do the
authors recommend specimens should be approached to maximise educational
effectiveness? Furthermore, other than using techniques outlined in their
paper to create the best views for models, are there any other ways in
which we should take advantage of this privileged access to cadaveric
tissue?
We would very much appreciate some advice and guidance with regards
to this, and once again we commend the authors for this innovative method
of teaching dissection.
References:
1. Adams JW, Paxton L, Dawes K, Burlak K, Quayle M, McMenamin PG, 3D
printed reproductions of orbital dissections: a novel mode of visualising
anatomy for trainees in ophthalmology or optometry, Br J Ophthalmol, 2015;
99(9): 1162-7
A Mataftsi et al1 published an interesting article regarding punctal
plugs in children. One of their aim was to establish the efficacy however
they have not mentioned any test (Schirmer, Tear film break-up time, Rose
Bengal staining, osmolarity) to confirm the diagnosis of dry eye and to
calibrate the tear deficiency. It was only the clinical impression
(flouresein staining is not specific for dry eyes and therefore cann...
A Mataftsi et al1 published an interesting article regarding punctal
plugs in children. One of their aim was to establish the efficacy however
they have not mentioned any test (Schirmer, Tear film break-up time, Rose
Bengal staining, osmolarity) to confirm the diagnosis of dry eye and to
calibrate the tear deficiency. It was only the clinical impression
(flouresein staining is not specific for dry eyes and therefore cannot be
used as diagnostic). In the follow up also, there was no yardstick to
measure and compare the post procedure improvement with the pre procedure
status. Only subjective feelings (patients or parents) are difficult to
gauge and therefore a scientific test at this stage would have established
the exact positive role of the plugs which could have been counterchecked
and verified by other workers. These tests could have been done in the
same sitting/ anesthesia and would not have required any additional visit
or anaesthesia.
A few points of this article differed markedly from previous articles. In
"Blepharokeratoconjunctivitis in children: diagnosis and treatment"2 by M
Viswalingam et al in which patients in Moorfields Eye Hospital, London,
UK, were analyzed, there is no mention of dry eye in either the text or
Table 1- Classification of the severity of blepharokeratoconjunctivitis
(BKC) in children and Table - 3 Clinical symptoms and signs. Punctate
erosions were present in only 9 % (all Asian) of their patients. Their
patients improved without any dry eye treatment. Similarly in "Visual
Outcome and Corneal Changes in Children with Chronic
Blepharokeratoconjunctivitis"3 by Jones SM et al, in patients analyzed in
Great Ormond Street Hospital for Children, London, UK, from1999 to 2005
(same hospital and almost same time period as is of the present article),
there was no mention of dry eye and punctate epithelial erosions (PEE)
were found in 31% of eyes. "In the authors' experience, effective
treatment for BKC should include a combination of both systemic and
topical antimicrobial therapy, along with topical steroids" was the
authors' recommendation in the above mentioned article and no punctal
plugs were mentioned. Now in the present article, authors have found a
lot of dry eyes (out of which 14 required punctual plugs) in BKC (and PEE
in 100%) among the almost same record which was used for the above
mentioned article and now they claim "plugs were successful in treating a
variety of causes of dry eye in our cohort, with more than half of the
children presenting with lipid deficiency secondary to meibomian gland
dysfunction".
Despite these observations, authors deserve appreciation for
introducing the new concept of punctal plug use in children.
References:
1. Mataftsi A, Subbu RG, Jones S, Nischal KK. The use of punctal plugs in
children. Br J Ophthalmol 2012;96:90-92.
2. Viswalingam M, Rauz S, Morlet N, Dart JK. Blepharokeratoconjunctivitis
in children: diagnosis and treatment. Br J Ophthalmol. 2005 Apr;89(4):400-
3.
3. Jones SM, Weinstein JM, Cumberland P, Klein N, Nischal KK. Visual
Outcome and Corneal Changes in Children with Chronic
Blepharokeratoconjunctivitis. Ophthalmology 2007;114:2271-2280
The rising use of Avastin injection for choroidal neovascular membranes
and other conditions has been successful in preliminary reports.
However, I have experienced 5 cases with optic neuropathy following
Avastin
injection after an interval of 2-4 months. Although my number of cases
is
very small, it suggests that a study be conducted to investigate the
effect of intravitreal Avastin on the optic nerve u...
The rising use of Avastin injection for choroidal neovascular membranes
and other conditions has been successful in preliminary reports.
However, I have experienced 5 cases with optic neuropathy following
Avastin
injection after an interval of 2-4 months. Although my number of cases
is
very small, it suggests that a study be conducted to investigate the
effect of intravitreal Avastin on the optic nerve using VEP.
Prof Dr Sherif Ahmed Kamel Amer
MBBCh, MSc ophthalmology, MD ophthalmology, Cairo University, ICO.Ophth.
Fellow of The Ophthalmology Department, Cairo University Hospitals (Kasr
Al Aini).
Supervisor of The Neuro-Ophthalmology Clinic
National Eye Center (Rod El Farag).
Ass Professor of Ophthalmology Beni Suif University, Egypt
We read with interest the remarks of Crowston et al. [1] on our
article entitled "Value of two mortality assessment techniques for organ
cultured corneal endothelium: trypan blue versus TUNEL technique".[2] We
showed that the TUNEL technique revealed a far higher percentage of
endothelial cells (ECs) irreversibly engaged in a cell death process than
that obtained by trypan blue staining.
We read with interest the remarks of Crowston et al. [1] on our
article entitled "Value of two mortality assessment techniques for organ
cultured corneal endothelium: trypan blue versus TUNEL technique".[2] We
showed that the TUNEL technique revealed a far higher percentage of
endothelial cells (ECs) irreversibly engaged in a cell death process than
that obtained by trypan blue staining.
The two techniques were performed sequentially: after observation of
trypan blue staining, corneas were immediately fixed in formaldehyde for
TUNEL. Crowston et al. suggest that the trypan blue itself and/or the time
spent outside the organ-culture medium before fixing in formaldehyde may
have caused an artefactual increase in the percentage of TUNEL-positive
ECs. Two arguments counter this remark:
1. The trypan blue staining procedure is identical to that used in all
European cornea banks that use organ culture during endothelial
examination(s) of grafts. Neither the low concentration of trypan blue
(0.4%) nor the short exposure time (about 1 minute) nor the short
incubation in the presence of 0.9% NaCl has ever been incriminated in ECs
over-mortality in routine practice.[3] Moreover, the innocuity of
injections of trypan blue into the anterior chamber, a common feature
during cataract surgery, has been well demonstrated.[4]
2. The time spent outside the organ-culture medium before fixing in
formaldehyde, a period required for vital staining and microscopic
examination of the endothelium, lasts only a few minutes. The cornea
remains under the microscope for about one minute only, the time needed
for image acquisition. Such rapidity is possible by using a prototype
automatic analyser of the endothelium, which we developed and have
recently published.[5] This is very probably insufficient time for DNA
fragmentation to occur in the proportion we observed. Moreover, the fixing
of the endothelial layer in 10% formaldehyde is immediate, and prevents
any continuation of fragmentation phenomena. On balance, it is highly
unlikely that the succession of markings is responsible for the
discrepancy between the positivity percentages of the two techniques. In
addition, we chose not to perform the two techniques simultaneously on
paired corneas or on the halves of one cornea because we wanted to
superimpose the two stains on the same cornea and thus obtain a double
cell staining.
The second remark by Crowston et al. is particularly interesting. We
too were surprised by the high percentage of TUNEL-positive ECs (mean
12.7%, SD 16.4). This may imply that all the cells died within 8 days,
which was evidently not the case. We believe this apparent contradiction
can be explained by the following theory. The TUNEL staining is positive
during a relatively long window (24-48 hours [6]). The TUNEL index,
measured at a given moment, provides a global view of all the cells with
fragmented DNA. However, the DNA fragmentation may be at different stages,
and the cells very likely spread according to a Gaussian distribution.
Therefore the cells, which are TUNEL-positive at a given moment, will not
all die instantaneously and simultaneously. Only the cells furthest to the
right on the curve will die in the very short term, and it is probably
these that are liable to be revealed by trypan blue. If it were possible
to perform TUNEL on two consecutive days, the percentage of positive cells
revealed would probably be very similar, but a large majority of the
positive cells recorded on the second day would have already been counted
on day one... It is, however, undeniable that the cells TUNEL-positive at a
given moment will all die eventually. In other words, we believe that, at
the end of storage, corneas contain a number of ECs engaged in an
irreversible cell-death process far more extensive than the highly
unreliable trypan blue staining technique suggests.
References
(1) Crowston JG, Healey PR, Maloof A, et al . Quantifying corneal
endothelial cell death. Br J Ophthalmol 2002;86:1068.
(2) Gain P, Thuret G, Chiquet C, et al . Value of two mortality assessment
techniques for organ cultured corneal endothelium: trypan blue versus
TUNEL technique. Br J Ophthalmol 2002;86:306-10.
(3) Sperling S. Evaluation of the endothelium of human donor corneas by
induced dilation of intercellular spaces and trypan blue. Graefes Arch
Clin Exp Ophthalmol 1986;224:428-34.
(4) Norn MS. Per operative trypan blue vital staining of corneal
endothelium. Eight years' follow up. Acta Ophthalmol 1980;58:550-5.
(5) Gain P, Thuret G, Kodjikian L, et al. Automated tri-image analysis of
stored corneal endothelium. Br J Ophthalmol 2002;86:801-8.
(6) Mesner PW, Epting CL, Hegarty JL, et al. A timetable of events during
programmed cell death induced by trophic factor withdrawal from neuronal
PC12 cells. J Neurosci 1995;15:7357-66.
In our paper entitled "Can fixation instability improve text
perception during eccentric fixation in patients with central scotomas?",[1]
we reported that patients with eccentric fixation can improve their
perception of a text by performing rapid eye movements back and forth
between two eccentric retinal areas, thus inducing a revival of
eccentrically projected images. An experimental set-up allowed us...
In our paper entitled "Can fixation instability improve text
perception during eccentric fixation in patients with central scotomas?",[1]
we reported that patients with eccentric fixation can improve their
perception of a text by performing rapid eye movements back and forth
between two eccentric retinal areas, thus inducing a revival of
eccentrically projected images. An experimental set-up allowed us to
reproduce the perceptual phenomenon and the refixational eye movements in
normal subjects. These subjects reported that a change in fixation
position induced a refreshment of the letter image, immediately after the
realisation of the eye movement. Improved perception lasted approximately
one second. When fixation was maintained stable, a rapid fading effect was
noted which reduced letter recognition. This suggested that performing
refixational eye movements counteracts the occurrence of a form of
perceptual filling-in, known as Troxler’s phenomenon.
We recently examined a patient with bilateral central scotomas and
eccentric fixation who reported that blinking enabled him to refresh the
projected image. This observation added to our understanding of mechanisms
counteracting Troxler’s phenomenon. Moreover, it may have useful practical
implications in rehabilitation procedures for low vision subjects.
Therefore we believed this finding deserves to be briefly reported.
Case report
We investigated the reading strategies of a 44 year old man with
bilateral central scotomas of about 20 degrees in diameter. His visual condition
resulted from Stargardt’s disease, diagnosed at the age of 18. Visual
acuity was 0.08 in the right eye and, 0.1 in the left eye. A Scanning
Laser Ophthalmoscope (SLO, Rodenstock, Munich, Germany) was used to
project letters, words and a paragraphed text onto his retina and to
assess his fixation behaviour. We also asked the patient to read word of
different length on a monitor.
We observed that while deciphering words he blinked in a voluntary
and repetitive manner. He was aware of the phenomenon and he explained
that blinking helped him to read because it induced a revival of word
image. He developed the habit of blinking more frequently when he could
not immediately read the presented text.
This phenomenon can be reproduced using the set up described in our
above-mentioned study by maintaining fixation on a dot and rapidly
blinking when the letter fades.
Comment
Our observations demonstrated the occurrence of two distinct clinical
mechanisms counteracting fading of letters projected onto peripheral
retina. The first consists of repeated changes of fixation whereas the
second relies on repeated blinking. Both mechanisms involve intermittent
suppression of letter projection on the concerned retinal area. Our
findings corroborate a previous report emphasizing the influence of
temporal variations of the visual stimulus on perceptual filling-in.
Experimentally, normal individuals observe reduction of the filling-in
process when exposed to a flickering background (de Weerd et al., 1995).
This phenomenon should be kept in mind by low vision therapists when
rehabilitating patients who report difficulties in distinguishing
eccentrically located images.
Reference
(1) A Déruaz, M Matter, A R Whatham, M Goldschmidt, F Duret, M Issenhuth, and A B Safran. Can fixation instability improve text perception during eccentric fixation in patients with central scotomas? Br J Ophthalmol 2004; 88: 461-463.
The article by Al-Hazmi et al.[1] states that combined trabeculotomy-
trabeculectomy with mitomyocin C (CTTM) gave better results than
trabeculotomy alone for primary congenital glaucoma (PCG) at the King
Khaled Eye Specialist Hospital (KKESH) in Riyadh, Saudi Arabia, between
1982 and 2002. For moderate PCG the success rate is stated as 40% and 80%
for trabeculotomy and CTTM, respectively. For severe...
The article by Al-Hazmi et al.[1] states that combined trabeculotomy-
trabeculectomy with mitomyocin C (CTTM) gave better results than
trabeculotomy alone for primary congenital glaucoma (PCG) at the King
Khaled Eye Specialist Hospital (KKESH) in Riyadh, Saudi Arabia, between
1982 and 2002. For moderate PCG the success rate is stated as 40% and 80%
for trabeculotomy and CTTM, respectively. For severe PCG the stated
success rate is 10% and 70% for trabeculotomy and CTTM, respectively.
However, without more specifics regarding when the trabeculotomies were
performed at KKESH, the authors cannot advocate CTTM over trabeculotomy
for moderate and severe PCG.
As the article states, over the years at KKESH the success rate for
trabeculotomy for PCG dramatically improved (29% from 1982-1990; 47% from
1991-94; 82% from 1995-2002) The authors attribute these improved results
over the years to improved primary healthcare facilities within the
kingdom, earlier referrals, better equipment availability, and surgeons
becoming more adapt at surgical intervention. In contrast, CTTM for PCG
was first performed at KKESH in 1994 with less of a “learning curve”; the
success rate from 1994 -2002 was 72%. The complication rate, however, was
higher for CTTM than for trabeculotomy.
Because initial trabeculotomy success for PCG at KKESH has
dramatically increased with time, it is important to know how many of the
reported trabeculotomy failures for moderate and severe PCG were from the
earlier periods of the hospital. This information was not in the
manuscript. It may be that trabeculotomy as currently performed at KKESH
for moderate and severe PCG has a success rate similar to that of CTTM for
the same patient population with less surgical complications.
References
1. Al-Hazmi A, Awad A, Zwaan Z, et al. Correlation between surgical
success rate and severity of congenital glaucoma. Br J Ophthalmol
2005;89:449–453.
The authors have investigated the and compared the chromosome 3
aberrations of Choroidal melanoma (CM) as determined by multiplex ligation
probe amplification (MLPA) or microsatellite analysis (MSA)in intra ocular
tumor biopsies with those results obtained from subsequent
endoresection/enucleation of the same Choroidal melanoma. However few
points need clarification from the authors:
1. Since the investigators used few ma...
The authors have investigated the and compared the chromosome 3
aberrations of Choroidal melanoma (CM) as determined by multiplex ligation
probe amplification (MLPA) or microsatellite analysis (MSA)in intra ocular
tumor biopsies with those results obtained from subsequent
endoresection/enucleation of the same Choroidal melanoma. However few
points need clarification from the authors:
1. Since the investigators used few markers on chromosome 3, technically
speaking the use of the word "Monosomy" is not appropriate to describe
the generic findings. This is at best can be called "Partial monosomy" or
even better, just describe the chromosome 3 locations of the deletions or
chromosome 8 duplications.
2. There are better genetic techniques currently available to detect
chromosomal deletions(s) and/or duplication(s) than multiplex ligation
probe amplification (MLPA) or micro-satellite markers. For example, array
comparative genomic hybridization (arrayCGH) high definition can be used
to screen the full genomic for chromosomal abnormalities and even detect
deletion(s) and/or duplication(s) as small as 10 Kb in size. The 100 ng of
DNA which was used by the investigators for MLPA can be easily used for
arrayCGH with small alterations to the protocol. This would make the
results more comprehensive and may able to detect other alterations on
other chromosomes.
3. The use of microsatellite markers to measure chromosomal abnormalities
(duplication or deletion) is not appropriate. Microsatellite markers, if
informative, can give you whether the tested individual is homozygous or
heterozygous for a particular allele. They are not design to give you a
quantitative answer and the peak height cannot be used for quantitative
measure.
4. It will be great if the authors can elaborate on the genes encompassed
in the deleted areas of chromosome-3 and how those genes may contribute to
the development and/or metastatic effect on the melanoma. For example, are
those genes involved in suppressing the tumor? or do they play some other
role ?
5. In Table-2, the authors list 13 patients with Chr3 loss vs. 12 patients
with no chr3 loss, can we actually use the deletion(s) on chr3 as a
genetic marker for choroidal melanoma?
Dear Editor
We read with interest the remarks of Crowston et al. [1] on our article entitled "Value of two mortality assessment techniques for organ cultured corneal endothelium: trypan blue versus TUNEL technique".[2] We showed that the TUNEL technique revealed a far higher percentage of endothelial cells (ECs) irreversibly engaged in a cell death process than that obtained by trypan blue staining.
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Dear Editor
We read with interest the article by Elder and Suter about what patients would like to know before having cataract surgery.[1] We congratulate the authors on investigating an area that has obviously been overlooked in ophthalmology. However we feel they failed to recognise some unique aspects of our specialty and also think that the nature of their study limits its practical application.
First...
Dear Editor,
We read with interest the paper published by Boschi, et. al.[1] in which immunohistochemistry was performed on orbital tissues from patients with thyroid associated ophthalmopathy (TAO) and compared to non...
Dear Editor,
We read the article '3D printed reproductions of orbital dissections: a novel mode of visualising anatomy for trainees in ophthalmology or optometry' by Adams JW. et al with great interest. The authors have successfully identified the need for experience handling and navigating through anatomical material to understand clinical ophthalmology. Furthermore, they have brilliantly created a means for th...
A Mataftsi et al1 published an interesting article regarding punctal plugs in children. One of their aim was to establish the efficacy however they have not mentioned any test (Schirmer, Tear film break-up time, Rose Bengal staining, osmolarity) to confirm the diagnosis of dry eye and to calibrate the tear deficiency. It was only the clinical impression (flouresein staining is not specific for dry eyes and therefore cann...
Dear Editor
The rising use of Avastin injection for choroidal neovascular membranes and other conditions has been successful in preliminary reports. However, I have experienced 5 cases with optic neuropathy following Avastin injection after an interval of 2-4 months. Although my number of cases is very small, it suggests that a study be conducted to investigate the effect of intravitreal Avastin on the optic nerve u...
Dear Editor
We read with interest the remarks of Crowston et al. [1] on our article entitled "Value of two mortality assessment techniques for organ cultured corneal endothelium: trypan blue versus TUNEL technique".[2] We showed that the TUNEL technique revealed a far higher percentage of endothelial cells (ECs) irreversibly engaged in a cell death process than that obtained by trypan blue staining.
...
Dear Editor
In our paper entitled "Can fixation instability improve text perception during eccentric fixation in patients with central scotomas?",[1] we reported that patients with eccentric fixation can improve their perception of a text by performing rapid eye movements back and forth between two eccentric retinal areas, thus inducing a revival of eccentrically projected images. An experimental set-up allowed us...
Dear Editor,
The article by Al-Hazmi et al.[1] states that combined trabeculotomy- trabeculectomy with mitomyocin C (CTTM) gave better results than trabeculotomy alone for primary congenital glaucoma (PCG) at the King Khaled Eye Specialist Hospital (KKESH) in Riyadh, Saudi Arabia, between 1982 and 2002. For moderate PCG the success rate is stated as 40% and 80% for trabeculotomy and CTTM, respectively. For severe...
The authors have investigated the and compared the chromosome 3 aberrations of Choroidal melanoma (CM) as determined by multiplex ligation probe amplification (MLPA) or microsatellite analysis (MSA)in intra ocular tumor biopsies with those results obtained from subsequent endoresection/enucleation of the same Choroidal melanoma. However few points need clarification from the authors: 1. Since the investigators used few ma...
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