Thank you for the opportunity to reply to the letter from Dr Alpins concerning our recent article "Astigmatism and the analysis of its surgical correction".[1] Noel Alpins is a widely respected contributor to many international meetings, having written comprehensively on the use of astigmatism vector analysis. His software program ASSORT TM is widely used for the planning of refractive surgery a...
Thank you for the opportunity to reply to the letter from Dr Alpins concerning our recent article "Astigmatism and the analysis of its surgical correction".[1] Noel Alpins is a widely respected contributor to many international meetings, having written comprehensively on the use of astigmatism vector analysis. His software program ASSORT TM is widely used for the planning of refractive surgery and provides many derived indices (transformations) from the vector analysis of both refractive and topographic astigmatism. Although the derived indices are summary measures, we have argued that their usefulness for statistical analysis is limited. This is because the perception of astigmatism is a psycho-physical phenomenon altered by the orientation of the axis of astigmatism (the power meridians of the cornea and crystalline lens). Unfortunately the perceptual response means that the measurement of the axis of astigmatism (which is with an arbitrary 180° scale) is non-linear in outcome terms, as related to visual acuity outcome. Astigmatism obliquity is the least desirable outcome but this is separated into two on the scale by with-rule-astigmatism (WTR), which is generally the most desirable outcome. Oblique astigmatism also separates the two groups of against-the-rule astigmatism (ATR) from the WTR astigmatism. Developments of vector analysis so far have not resolved this issue of non-linearity of the axis of astigmatism compared with the visual outcome. Dr Alpins recognised the relative value of WTR astigmatism and described how to plan refractive corrections using this principle in his January 1997 article (Figure 10a, J Cataract Refract Surg 1997;23:65-75, reference 33 in our article). We suggested the "by-the-rule" transformation would help eliminate the problem of divided oblique and WTR astigmatism, but this makes the use of vector analysis difficult and does result in data compression.
I agree that my understanding of astigmatism is incomplete. With over 4000 responses to a search for astigmatism on PubMed, there is much to know and yet more still unknown. The references cited in the article were simply representative or illustrative of the arguments discussed in the article. By way of apology, the correct reference for the "surgical error" (originally given as 34) in Figure 7, equation 20, and the relevant text page 1131 should in fact be reference 70, Noel Alpins' first article on vector analysis. The surgical error is the arithmetic result of the preoperative vector combined with the surgically induced vector (SIA), less the target induced vector (TIA), which is analogous to neutralising a lens with another of the opposite sign (hence the reverse direction arrow). This produces two outcome measures, the difference in magnitude and axis. However, as our article's discussion on obliquely crossed cylinders described, misalignment due to rotation of the corrective cylinder produces not only an error in cylinder magnitude and axis, but also a spherical power error. Because of this interdependence all three should be analysed together, but this produces statistical difficulties. One way around this problem is to use an appropriate summary measure of the outcome instead.
The surgical error may be applied to treatments targeting non-zero goals despite not addressing changes in corneal shape. As an outcome measure of the surgical process it is equally applicable to the arithmetic result of the SIA with the TIA as it is with the SIA and the preoperative astigmatism vector. The transformation of the error between the SIA and the preoperative astigmatism vector into the "difference vector" (which is a mathematically precise and absolute measure of the surgical error) unfortunately does not address the problem of non-linearity (i.e. the relative value in terms of visual acuity outcome) so is not useful as a summary measure of the outcome. However the difference may be useful in understanding the effects of the surgery (i.e. as a process measure) and for deriving the "index of success".
Dr Alpins describes the SIA "torque" effect with reference to the preoperative axis of astigmatism (or the TIA) in his December 1997 article not cited in our Perspective article (J Cataract Rafract Surg 1997;23:1503-14). Torque needs to be distinguished from the effect of rotation of the corrective cylinder that is derived from the post-operative astigmatism value. Unfortunately, our discussion on the optical decomposition did not clearly state that the 45° polar value is derived from the postoperative result, thus correctly describes the rotation effect (as discussed with the obliquely crossed cylinder effects). We apologise for creating some confusion with the "torque" effect.
We agree that the healing response is connected to the surgical process, however healing is a very individual response. Vector analysis in terms of the SIA can only reflect the surgical process. Although a "vector" could be used to represent the measurement of the healing response at any point in time, it may not be representative of the healing responses at other times because the healing process is continuous. Furthermore an individual's response may not be well represented by the aggregate or mean vectorial response, which as discussed, is compounded by the non-linearity problem of the separation of the oblique and ATR astigmatism axis values (see reference 104 from our article).
In his early 1997 article (reference 33) Noel Alpins discusses surgical treatment planning combining the topographic astigmatism values with the refractive values to produce an optimal corneal curvature. Dr Alpins suggests that the surgical emphasis is best directed towards a WTR result when there is a disparity between the values requiring some residual astigmatism after surgery. Without recognising Javal's rule, Dr Alpins nonetheless has ascribed a better relative value to ATR astigmatism suggesting that optimal treatment planning be based on this psycho-physical phenomenon. As we stated "only using keratometric data for the planning of refractive surgery" would create a problem otherwise.
It is understandable that Dr Alpins feels that the concepts presented in our article are in conflict with some of his own, but these do not diminish the value of vector analysis as a process measure, particularly for individual cases. It is the use of vector analysis as an outcome measure relative to the visual acuity that was critically evaluated by our article.
Reference
(1) Morlet N, Minassian D, Dart J. Astigmatism and the analysis of its surgical correction. Brit J Ophthalmol 2001;85:1127-38.
We read with interest the paper by Gain et al. [1] which assessed two distinct
techniques to quantify corneal endothelial cell death in
donor corneas. A significantly higher rate of cell death
was observed with the TUNEL assay which labels
nuclei with fragmented DNA, compared to the trypan
blue exclusion method, which detects cells with
disrupted cell membranes. The authors conclude that...
We read with interest the paper by Gain et al. [1] which assessed two distinct
techniques to quantify corneal endothelial cell death in
donor corneas. A significantly higher rate of cell death
was observed with the TUNEL assay which labels
nuclei with fragmented DNA, compared to the trypan
blue exclusion method, which detects cells with
disrupted cell membranes. The authors conclude that
TUNEL analysis is more accurate than trypan blue
exclusion as a means of assessing the impact of
different corneal storage methods on endothelial
viability.
Our experience of using a number of cell death assays
to investigate fibroblast apoptosis together with the
findings of others [2,3] supports the notion that trypan
blue exclusion is not a good method for detecting
apoptosis in vitro. However, we would like to propose
that the sequential analysis of the same corneal tissue
in this study might account for some of the disparity
observed between the two methods. Following initial
incubation in trypan blue, buttons were subjected to
image analysis as well as cell density measurements
after further incubation in 0.9 % sodium chloride. After
this the buttons were fixed overnight in 10 %
formaldehyde in preparation for TUNEL. It is possible
that the higher rates of death observed by TUNEL
reflect the known toxicity of trypan blue, or are a
consequence of subsequent manipulation in image
analysis and cell density measurement. The low rates
of cell death observed by both techniques in non-stored
corneas do not negate this possibility, since healthier
corneas may be more resistant to the effects of trypan
blue and subsequent analysis. Randomisation of the
sequence of analysis between the techniques
compared would not have been possible, but the
authors could have divided the corneas before storage
or used paired eyes as separate matched specimens.
The authors argue that the disparity between
endothelial cell loss and observed cell death is greater
for trypan blue exclusion because loss of membrane
integrity occurs relatively late, giving a shorter
observational window in which to detect dying cells
than TUNEL analysis, which detects apoptosis earlier.
But the relatively high percentage of apoptotic cells
(12.7 %) observed by TUNEL analysis may be an
overestimate. Although the time span for apoptosis
varies greatly depending on the cell type and nature of
the apoptotic trigger, many estimates suggest that the
processes is completed in less than 24 hours.[4] If
12.7 % of cells undergo apoptosis at any given time it
can be predicted that complete endothelial cell death
would occur within 8 days. The actual loss observed
over the 22-day incubation period in this study was
however only around 14 %.
We agree with the authors regarding the need for
accurate methods for determining endothelial cell
death. No individual assay per-se, is ideal for both
quantifying and determining the mode of cell death and
combinations of assays should give a clearer picture
of the impact of variations in corneal storage on
endothelial viability.
References
(1) Gain P, Thuret G, Chiquet C, Dumollard JM, Mosnier JF, Burillon C, Delbosc B, Hervé P, Campos L. Value of two mortality assessment techniques for organ cultured corneal endothelium: trypan blue versus TUNEL
technique. Br J Ophthalmol 2002;86:306-10.
(2) McCloskey, TW et al. Comparison of seven
quantitative assays to assess lymphocyte cell death
during HIV infection: measurement of induced
apoptosis in anti-Fas-treated Jurkat cells and
spontaneous apoptosis in peripheral blood
mononuclear cells from children infected with HIV.
AIDS Res Hum Retroviruses 1998;14(16):1413-22.
(3) Crowston, JG et al. Antimetabolite-induced
apoptosis in Tenon's capsule fibroblasts. Invest
Ophthalmol Vis Sci 1998;39(2):449-54.
(4) Kravtsov, VD, Daniel TO, Koury MJ.
Comparative analysis of different methodological
approaches to the in vitro study of drug-induced
apoptosis. Am J Pathol 1999;155(4):1327-39.
We have read with avid interest the article by Gupta et al. on the use of bovine pericardium as a wrapping material for hydroxyapatite orbital implants.[1] We are highly impressed by their results as none of the patients had implant extrusion. This is really commendable since implant extrusion rate has ranged from 9 % to 21 % in previous studies,[2] and it indicates meticulous technique and follow up....
We have read with avid interest the article by Gupta et al. on the use of bovine pericardium as a wrapping material for hydroxyapatite orbital implants.[1] We are highly impressed by their results as none of the patients had implant extrusion. This is really commendable since implant extrusion rate has ranged from 9 % to 21 % in previous studies,[2] and it indicates meticulous technique and follow up. We would like to clarify a few pertinent issues.
Although bovine pericardium is generally considered non-reactive, it has been reported to produce severe inflammatory reaction in cardiac use.[3] Another area of major concern with cardiovascular use of bovine pericardium has been development of calcification seen in both laboratory studies and cardiac patients.[4] It is still uncertain what impact such a calcification would have on an orbital implant and assessment of its effect would certainly require studies with a larger number of patients and longer follow up. However, it has been suggested that it may hamper its motility.[2] We suggest that the possibility of misinterpretation of imaging findings in cases of orbital recurrence of tumours should not be overlooked.
Another crucial area of concern is the risk of infection with xenografts, which cannot be totally eliminated even by highly stringent screening and processing procedures. We are referring to the group of bovine spongiform encephalopathies including Creutzfeld-Jakob disease (CJD) and its variant found in the United Kingdom (CJDv).
Therefore, the quest for a comparable synthetic wrapping material and better implants which do not require wrapping continues, and bovine pericardium should be considered, keeping in view its above mentioned shortcomings.
Mandeep S. Bajaj, MD
Neelam Pushker, MD
Dr Rajendra Prasad Centre for Ophthalmic Sciences
All India Institute of Medical Sciences
Ansari Nagar, New Delhi - 110 029
India
References
(1) Gupta M, Puri P, Rennie IG. Use of bovine pericardium as a wrapping material for hydroxyapatite orbital implants. Br J Ophthalmol 2002;86:288-9.
(2) Gayre GS, Debacker C, Lipham W, et al. Bovine pericardium as a wrapping for orbital implants. Ophthal Plast Reconstr Surg 2001;17:381-7.
(3) Skinner JR, Kim H, Toon RS, et al. Inflammatory epicardial reaction to processed bovine pericardium: case report. J Thorac Cardiovas Surg 1984;88: 789-91.
(4) Braile DM, Ardito RV, Greco OT, et al. IMC bovine pericardial valve: 11 years. J Card Surg 1991;6:580-8.
We read with great interest the article by Takei et al..[1] We
agree with the authors that axial length (AL) measurement in silicone
oil-filled eyes is a difficult situation. The need for accurate estimation
of AL has increased following advances in vitreoretinal surgical techniques
and improved visual results. We complement Takei and colleagues for an
excellent report on the matter. CT scanning for...
We read with great interest the article by Takei et al..[1] We
agree with the authors that axial length (AL) measurement in silicone
oil-filled eyes is a difficult situation. The need for accurate estimation
of AL has increased following advances in vitreoretinal surgical techniques
and improved visual results. We complement Takei and colleagues for an
excellent report on the matter. CT scanning for AL measurement is a novel
technique, but not without pitfalls.
We had studied AL in 28 eyes pre and post-silicon oil removal (viscosity
1000 centistoke) using A-scan ultrasonography in the sitting position and
found that the ratio between actual AL and AL measured in silicon oil-filled
eyes varied widely, from 0.64 to 0.92. This is in contrast to the study by
Murray et al.[2] who showed minimal variability and could derive a
mathematical constant of 0.71 to calculate AL in silicon oil-filled eyes to
get the actual AL.
We did find that the AL in the fellow eye compared well with the post SO
removal AL. Although the best method of biometry in silicon oil-filled eyes
still eludes us, we feel that AL measurement prior to the vitreo-retinal
procedure may be the best option (using combined A and B scan
ultrasonography). Failing that, AL in the fellow eye may give a fair
estimate. However the claims of CT scan for accurate determination of AL
needs further evaluation and refining considering its lack of easy
availability, high cost and irradiation exposure.
References
(1) Takei K, Sekine Y, Okamoto F and Hommura S. Measurement of axial
length of eyes with incomplete filling of silicone oil in the vitreous
cavity using X-ray computed tomography. Br J Ophthalmol 2002;86:47-50.
(2) Murray DC, Potamitis T, Good P, Kirkby GR, Benson MT. Biometry of
the silicone oil-filled eye. Eye 1999 Jun;13; 319-24.
I read with great interest the excellent perspective by Plsková et al1 in which they raise the issue of transient corneal opacification following corneal transplantation in the mouse model and argue that it might be due to a sufficient number of endothelia[l] cells regaining function.
What the authors describe for the mouse model, also occurs in the rat model. In fact most researchers in the rat model pr...
I read with great interest the excellent perspective by Plsková et al1 in which they raise the issue of transient corneal opacification following corneal transplantation in the mouse model and argue that it might be due to a sufficient number of endothelia[l] cells regaining function.
What the authors describe for the mouse model, also occurs in the rat model. In fact most researchers in the rat model probably have this experience, but for some reason do not think it is very important and/or choose to ignore it. Apart from the article by Williams et al[2], there is - as far as I know - only one other author who has explicitly mentioned this transient opacification. In his paper, Herbort[3] wrote "The grafts began clearing 4 weeks after surgery … and vessels in the graft diminished from 6 weeks post-surgery." and "It has to be noted that after acute rejection most corneas regain some clarity by 7-8 weeks." Transient corneal opacification also occurs in the rat model I used[4] (AO rats (strain RT1u) served as recipients of corneas from PVG rats (strain RT1c) and corneas were sutured with a single running suture). Allogeneic transplanted corneas showed no initial opacification immediately postoperative; neither did the syngeneic controls. All allogeneic corneas "rejected" (or more precisely showed total
opacification) around day 11-13 and those corneas, when followed long enough, all cleared. Opacification remained higher than 2 (meaning an increased corneal haze, but some anterior chamber structures still visible) at days 17-21 and became lower than 2 (slight haze) around days 21-32.
It would be exciting to know if the hypothesis put forward by Plsková et al1 would also apply to the rat model and to find out if this 'clearing' of the opacification also occurs in other rat strains than the ones mentioned.
Plsková et al have brought up a very important topic where a lot of uncertainty still exists, which warrants further research.
REFERENCES
(1) Plsková J, Kuffová L, Holán V, Filipec M, Forrester JV. Evaluation of corneal graft rejection in a mouse model. Br J Ophthalmol 2002;86:108-113.
(2) Williams KA, Coster DJ. Penetrating corneal transplantation in the inbred rat; a new model. Invest Ophthalmol Vis Sci 1985;26:23-30.
(3) Herbort CP, Matsubara M, Nishi M, Mochizuki M. Penetrating keratoplasty in the rat: a model for the study of immunosuppressive treatment of graft rejection. Jpn J Ophthalmol 1989;33:212-220.
(4) Claerhout I, Beele H, Verstraete A, Van den Broecke C, Kestelyn P. The effect of duration and timing of systemic cyclosporine therapy on corneal allograft survival in the rat model. Graefe's Arch Clin Exp Ophthalmol 2001;239:152-157.
Dr Ilse Claerhout
Department of Ophthalmology
Ghent University Hospital
De Pintelaan 185
9000 Gent
Belgium
Ilse.claerhout@rug.ac.be
We thank Dr. Panda for her comments on our recent paper entitled
"Treatment of fungal keratitis by penetrating keratoplasty". Dr. Panda
noted correctly that treatment modalities differ on different types of
keratitis. About 20% of the cases in our study were mixed infections, that
is, fungal infection combined with bacterial or herpes simplex virus
infection. However, the focus of our study was to s...
We thank Dr. Panda for her comments on our recent paper entitled
"Treatment of fungal keratitis by penetrating keratoplasty". Dr. Panda
noted correctly that treatment modalities differ on different types of
keratitis. About 20% of the cases in our study were mixed infections, that
is, fungal infection combined with bacterial or herpes simplex virus
infection. However, the focus of our study was to study the treatment of
severe fungal keratitis cases that could not be controlled by antifungal
medication. KOH wet mount was prepared for all the infected eyes. Though
calcoflour white and acridine orange stain have become popular in the
world, it is difficult to get them in China now. In addition, we do not
feel that KOH wet mount preparation can be substituted by normal saline
smear method, because KOH can dissolve the impurities in the smear so that
the fungal filaments could be seen more clearly through the microscope.
We gave systemic antifungal medication to all the patients, but just
orally for 2 to 3 weeks for the purpose of preventing recurrent fungal
infection after PKP. We agree that fluconazole is only effective on a few
genera of fungi. However, usually it takes at least 3 days to identify the
infected fungi through fungal culture, so we used fluconazole combined
with natamycin or amphotericin B before the fungi were identified.
Furthermore, it is quite necessary to go on using antifungal medication
topically during and after surgery in case the infected tissue has not
been removed in its entirety. Topical antifungal medication is inevitably
epitheliotoxic, which may be endurable comparing with the recurrence of
fungal infection.
Dr. Panda is interested in the characteristic feature of fungi. We
reported it in another recent publication regarding fungal keratitis. [1]
In our study, the patients we performed PKP on were those with fungal
infection that could not be controlled by antifungal medication. We had
observed that more complications would occur after PKP in patients with
fungal keratitis than those with keratococus. However, the result of this
study was exciting, because we attached great importance to the prevention
of complications after surgery. A series of scientific articles written in
Chinese by us regarding this point has been published in the medical
journals in China, and we are preparing manuscripts submitted to journals
published in English in order to introduce them to international
colleagues.
A point of concern was raised about large graft. The optical result
is related to the size of graft, that is, patients with large grafts can
obtain better visual acuity than those with small ones. As long as the
infected tissue has been thoroughly removed, the only thing we need to do
after surgery is to prevent immunorejection.
Amniotic membrane transplantation has been performed at our hospital
for some recalcitrant corneal ulcers, and satisfactory effects were
achieved. Also, we have tried this therapy in a few cases of fungal
keratitis in which the infection just reached the superficial corneal
stroma and was completely removed, but did not get good postoperative
visual acuity. Therefore, at present, only LKP was chosen for the
treatment of fungal infection at the superficial or middle stroma at our
hospital.
Lixin Xie, MD
Shandong Eye Institute & Hospital
Qingdao 266071, P. R. China
References
(1) Xie L, Shi W, Liu Z, Li S. Lamellar keratoplasty for the treatment of
fungal keratitis. Cornea 2002;21:33-7
We have read with keen interest the article on trachomatous
trichiasis by Bowman et al. We fully endorse the authors' observations that
Trachoma and its sequelae are on the decline even in developing countries
as we are witnessing similar trends in south-east Asia,particlarly India.
However,we would like to raise a few pertinent issues.
It is our considered opinion that self-epilation of tri...
We have read with keen interest the article on trachomatous
trichiasis by Bowman et al. We fully endorse the authors' observations that
Trachoma and its sequelae are on the decline even in developing countries
as we are witnessing similar trends in south-east Asia,particlarly India.
However,we would like to raise a few pertinent issues.
It is our considered opinion that self-epilation of trichiatic
eyelashes should not be encouraged as it requires a considerable degree of
patient education and training.In patients with compromised vision due to
corneal opacities,prebyopes and those with poor training skills,it can
prove to be a fairly risky proposition as the patient may inadvertantly
damage vital stuctures such as the cornea and eyelid margin.
Secondly, even in cases which the authors have classified as minor
forms of trichiasis,repeated epilation may not be a preferable option as
the eyelashes which regrow after epilation are usually short with
extremely sharp tips and carry a greater potential for corneal damage than
the longer,unepilated eyelashes.Repeated epilation could lead to
alteration in morphology of the sharp posterior lid margin,which is so
crucial for tear film dynamics and lacrimal pump function.
Therefore,in our experience,we feel that patients with
trichiasis,whether major or minor,should be subjected to a definitive
procedure after the active trachomatous process has been controlled.This
would entail surgical intervention if associated with a marked degree of
entopion,or electrolysis if the trichiatic component alone is predominant.
We read with interest the letter from Amin et al [1], suggesting a modification of the sub-tenon local anaesthetic injection procedure. They advocate the use of a venflon needle to penetrate the conjunctiva, with subsequent advancement of the cannula prior to anaesthetic injection. We are concerned that the use of a sharp needle should be recommended so close to the eye. Amin et al point out that the needle ti...
We read with interest the letter from Amin et al [1], suggesting a modification of the sub-tenon local anaesthetic injection procedure. They advocate the use of a venflon needle to penetrate the conjunctiva, with subsequent advancement of the cannula prior to anaesthetic injection. We are concerned that the use of a sharp needle should be recommended so close to the eye. Amin et al point out that the needle tip is clearly visible at all times and therefore at "minimal risk" of puncturing the eye. However, once under the conjunctiva, the needle is not necessarily "clearly" visible, and if subconjunctival haemorrhage should occur then it will quickly become obscured. We do not think it sensible to place a sharp needle this close to the eye when an effective and well proven alternative delivery system has already stood the test of time [2].
In his editorial on local anaesthetic injection techniques for cataract surgery, Smerdon [3] rightly emphasizes the risk of ocular penetration for all techniques involving needles, and highlights the Royal College of Ophthalmologists local anaesthesia survey[4] which demonstrated the relative safety of sub-tenon's and topical anaesthesia. We agree with him that when discussing an anaesthetic technique with a potential for high volume, it is not the expert anaesthetist/ophthalmologist who should be borne in mind, but rather the less skilled person, possibly less familiar with ophthalmic anaesthetic techniques, or in training, who may be required to administer a block. It is in this setting that the use of a needle very close to the eye is, in our opinion, an unwarranted risk. Surely the "no needle" sub-tenon's technique is just as effective, and safer.
References:
(1) Amin S, Minihan M, Lesnik-Oberstein S, Carr C. A new technique for delivering sub-Tenon's anaesthesia in ophthalmic surgery. Br J Ophthalmol 2002; 86; 119.
(2) Stevens JD. A new local anaesthesia technique for cataract extraction by one quadrant sub-tenon's infiltration. Br J Ophthalmol 1992; 76: 670-4.
(3) Smerdon D. Needle local anaesthesia for cataract surgery: a chip off the old block? Eye (2001) 15, 439-440.
(4) Eke T, Thompson JR. The national survey of local anaesthesia for ocular surgery. II. Safety profiles of local anaesthesia techniques. Eye 1999; 13: 196-204.
I congratulate Riordan-Eva et al for the article on temporal artery biopsy in the management of giant cell arteritis with neuro-ophthalmic complications.[1] This is an excellent article for residents, ER physicians, Family Practice physicians and Ophthalmologists.
The 3 cases discussed clearly show that patients over the age of 50 presenting with temporary or permanent visual loss or binocular dipl...
I congratulate Riordan-Eva et al for the article on temporal artery biopsy in the management of giant cell arteritis with neuro-ophthalmic complications.[1] This is an excellent article for residents, ER physicians, Family Practice physicians and Ophthalmologists.
The 3 cases discussed clearly show that patients over the age of 50 presenting with temporary or permanent visual loss or binocular diplopia and with or without systemic signs of temporal arteritis must have at least SED rate checked. If the suspicion is high the patient must be started on high dose steroids. We prefer IV solumedrol for the first 3-4 days followed by prednisone by mouth. A Medrol dose pack that is given for 5 days in tapering doses is not adequate.
We perform temporal artery at convenience within 2 weeks. When available we prefer to do frozen section on the affected side. If negative we do the other side. When frozen section is not available we do routine biopsy on the affected side and prefer to wait for the results. We do not do bilateral temporal artery biopsy at the same time.
As mentioned in the article the biopsy should be at least 2-2.5 mm and the pathologist must be adequately trained to interpret temporal artery biopsies. With negative biopsies on both sides provided the above criteria are met we conclude that the patient has no GCA.
References
(1) Riordan-Eva, P, Landau, K, and O'Day, J. Temporal artery biopsy in the management of giant cell arteritis with neuro-ophthalmic complications. Brit J Ophthalmol 2001 85: 1248-1251.
It was with great interest that I read the recent article by Dr. al Arab and co-workers entitled "The Burden of Trachoma and the Royal Nile Delta of Egypt; the Survey of Menofiya Governerate".[1] This work clearly shows that endemic blinding trachoma continues to be a major health problem in this area of the Nile Delta, quite close to Cairo.
My attention was particularly drawn to the high rate of recurren...
It was with great interest that I read the recent article by Dr. al Arab and co-workers entitled "The Burden of Trachoma and the Royal Nile Delta of Egypt; the Survey of Menofiya Governerate".[1] This work clearly shows that endemic blinding trachoma continues to be a major health problem in this area of the Nile Delta, quite close to Cairo.
My attention was particularly drawn to the high rate of recurrence amongst those who had had trichiasis surgery. Overall, 44% of cases who had had surgery had recurrent trichiasis. It would be most interesting to look at the time that had elapsed between surgery, and the time of examination. Some have argued that the recurrence rate from trichiasis reflects poor or inadequate surgery. Others have alluded to the fact that the tarsal scarring trachoma is of a progressive nature and that trichiasis is likely to recur because of ongoing scarring, even after otherwise successful surgery. Information of the elapsed time would help explore the scenario.
References
(1) al Arab, GE, Tawfik, N, El Gendy, R, et al. The Burden of Trachoma and the Royal Nile Delta of Egypt; the Survey of Menofiya governerate, Brit J Ophthalmol 2002;85;1406-1410).
Dear Editor
Thank you for the opportunity to reply to the letter from Dr Alpins concerning our recent article "Astigmatism and the analysis of its surgical correction".[1] Noel Alpins is a widely respected contributor to many international meetings, having written comprehensively on the use of astigmatism vector analysis. His software program ASSORT TM is widely used for the planning of refractive surgery a...
Dear Editor
We read with interest the paper by Gain et al. [1] which assessed two distinct techniques to quantify corneal endothelial cell death in donor corneas. A significantly higher rate of cell death was observed with the TUNEL assay which labels nuclei with fragmented DNA, compared to the trypan blue exclusion method, which detects cells with disrupted cell membranes. The authors conclude that...
Dear Editor
We have read with avid interest the article by Gupta et al. on the use of bovine pericardium as a wrapping material for hydroxyapatite orbital implants.[1] We are highly impressed by their results as none of the patients had implant extrusion. This is really commendable since implant extrusion rate has ranged from 9 % to 21 % in previous studies,[2] and it indicates meticulous technique and follow up....
Dear Editor
We read with great interest the article by Takei et al..[1] We agree with the authors that axial length (AL) measurement in silicone oil-filled eyes is a difficult situation. The need for accurate estimation of AL has increased following advances in vitreoretinal surgical techniques and improved visual results. We complement Takei and colleagues for an excellent report on the matter. CT scanning for...
I read with great interest the excellent perspective by Plsková et al1 in which they raise the issue of transient corneal opacification following corneal transplantation in the mouse model and argue that it might be due to a sufficient number of endothelia[l] cells regaining function.
What the authors describe for the mouse model, also occurs in the rat model. In fact most researchers in the rat model pr...
Dear Editor,
We thank Dr. Panda for her comments on our recent paper entitled "Treatment of fungal keratitis by penetrating keratoplasty". Dr. Panda noted correctly that treatment modalities differ on different types of keratitis. About 20% of the cases in our study were mixed infections, that is, fungal infection combined with bacterial or herpes simplex virus infection. However, the focus of our study was to s...
Dear Editor,
We have read with keen interest the article on trachomatous trichiasis by Bowman et al. We fully endorse the authors' observations that Trachoma and its sequelae are on the decline even in developing countries as we are witnessing similar trends in south-east Asia,particlarly India. However,we would like to raise a few pertinent issues.
It is our considered opinion that self-epilation of tri...
We read with interest the letter from Amin et al [1], suggesting a modification of the sub-tenon local anaesthetic injection procedure. They advocate the use of a venflon needle to penetrate the conjunctiva, with subsequent advancement of the cannula prior to anaesthetic injection. We are concerned that the use of a sharp needle should be recommended so close to the eye. Amin et al point out that the needle ti...
I congratulate Riordan-Eva et al for the article on temporal artery biopsy in the management of giant cell arteritis with neuro-ophthalmic complications.[1] This is an excellent article for residents, ER physicians, Family Practice physicians and Ophthalmologists.
The 3 cases discussed clearly show that patients over the age of 50 presenting with temporary or permanent visual loss or binocular dipl...
It was with great interest that I read the recent article by Dr. al Arab and co-workers entitled "The Burden of Trachoma and the Royal Nile Delta of Egypt; the Survey of Menofiya Governerate".[1] This work clearly shows that endemic blinding trachoma continues to be a major health problem in this area of the Nile Delta, quite close to Cairo.
My attention was particularly drawn to the high rate of recurren...
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