We thank Drs Madill and Ffytche for their interesting comments on our
paper [1] and are grateful for the opportunity to respond to some of the
issues raised. The first relates to possible variations in the prevalence
rate of Charles Bonnet syndrome (CBS) in different populations, on which
there is currently very little substantive data. We agree that additional
population-based studies are necessary to d...
We thank Drs Madill and Ffytche for their interesting comments on our
paper [1] and are grateful for the opportunity to respond to some of the
issues raised. The first relates to possible variations in the prevalence
rate of Charles Bonnet syndrome (CBS) in different populations, on which
there is currently very little substantive data. We agree that additional
population-based studies are necessary to determine whether the
differences found between ethnic groups are consistent. We wish to
highlight that our findings [1] are supported by another recently
published study of 1000 Japanese patients by Shiraishi et al [2] which
reported a prevalence rate of 0.5% compared to 0.4% in our study
population. Since the methodology and diagnostic criteria used in that
study are very similar to ours, the comparable prevalence rates reported
in both studies may be a true reflection of a lower prevalence of CBS in
Asians compared to Western populations.
We would like to point out that the large variation in prevalence
rates of CBS in the various cross-sectional studies may be explained by
the characteristics of the different populations being screened,
especially the degree of visual impairment. When patients were drawn from
either a general ophthalmology [1-3] or general medical [4] clinic,
presumably comprising patients with relatively good visual acuity, the
prevalence rates ranged from 0.4 – 2%. In patients with poorer visual
acuity [3, 5-8], the prevalence rates varied from 11 – 12.3%. This
observation suggests that poor visual acuity may be a factor that
increases the risk of developing CBS. Indeed, Teunisse showed that the
risk of CBS was higher in patients with a LogMAR visual acuity of less
than 0.3 [3] and Holroyd also found an association with bilateral visual
acuity of 20/60 or less [9].
Nevertheless, even if reduced visual acuity is indeed a risk factor
for the development of CBS, we agree that a reduction in visual acuity is
not essential and that CBS can occur in patients with relatively good
visual acuity. Gold et al felt that reduced visual acuity is not a
prerequisite for the diagnosis of CBS [10] and Holroyd suggested that it
may be the presence of visual impairment and not the severity of visual
loss that predisposes to CBS [4]. Schultz et al, in an excellent review of
the cases reported in the literature, found that the visual acuities of
patients diagnosed with CBS ranged from normal to no light perception
[11]. It is becoming apparent that CBS can develop in patients with
visual field defects but otherwise good central acuity. The patients
described by Drs Madill and ffytche and our own patient (patient 3) had
glaucomatous visual field defects. A recent paper by Freiman et al [12]
documented the presence of hallucinations manifesting within visual field
defects that occurred following neurosurgery. Two interesting points can
be noted from Freiman et al’s series: first, the hallucinations were
confined to the area of visual loss. Second, they began soon after the
surgery and resolved within days to 6 months after their onset [4]. In
contrast, in 3 of 4 patients reported by Drs Madill and ffytche as well as
our own patient, the hallucinations were not restricted to the visual
field defect. The relationship of the onset of CBS symptoms to the
development of visual field defects as well as the localization of
hallucinations within visual fields are issues that warrant further study
as they may provide additional insight into the pathophysiology of CBS.
References
(1) Tan CSH, Lim VSY, Ho DYM, Yeo E, Ng BY, Au Eong KG. Charles
Bonnet syndrome in Asian patients in a tertiary ophthalmic centre. Br J
Ophthalmol 2004; 88: 1325-1329.
(2) Shiraishi Y, Terao T, Ibi K, Nakamura J, Tawara A. The rarity of
Charles Bonnet syndrome. J Psychiatr Res. 2004 Mar-Apr;38(2):207-13
(3) Teunisse RJ, Cruysberg JR, Verbeek AL, Zitman FG. The Charles
Bonnet syndrome: a large prospective study in the Netherlands. Br J
Psychiatry 1995; 166: 254-257.
(4) Holroyd S, Rabins PV, Finkelstein D, Lavrisha M. Visual
hallucinations in patients from an ophthalmology clinic and medical clinic
population. J Nerv.Ment.Dis. 1994;182:273-6.
(5) Brown GC, Murphy RP. Visual symptoms associated with choroidal
neovascularization. Photopsias and the Charles Bonnet syndrome.
Arch.Ophthalmol. 1992;110:1251-6.
(6) Olbrich HM, Engelmeier MP, Pauleikhoff D, Waubke T. Visual
hallucinations in ophthalmology. Graefes Arch.Clin.Exp.Ophthalmol.
1987;225:217-20.
(7) Teunisse RJ, Cruysberg JR, Hoefnagels WH, Verbeek AL, Zitman FG.
Visual hallucinations in psychologically normal people: Charles Bonnet's
syndrome. Lancet 1996;347:794-7.
(8) Nesher R, Nesher G, Epstein E, Assia E. Charles Bonnet syndrome
in glaucoma patients with low vision. J Glaucoma. 2001;10:396-400.
(9) Holroyd S, Rabins PV, Finkelstein D, Nicholson MC, Chase GA,
Wisniewski SC. Visual hallucinations in patients with macular
degeneration. Am J Psychiatry 1992; 149: 1701-1706.
(10) Gold K, Rabins PV. Isolated visual hallucinations and the
Charles Bonnet syndrome: a review of the literature and presentation of
six cases. Compr.Psychiatry 1989;30:90-8.
(11) Schultz G, Melzack R. The Charles Bonnet syndrome: 'phantom
visual images'. Perception 1991;20:809-25.
(12) Freiman TM, Surges R, Vougioukas VI, Hubbe U, Talazko J, Zentner
J, Honegger J, Schulze-Bonhage A. Complex visual hallucinations (Charles
Bonnet syndrome) in visual field defects following cerebral surgery.
Report of four cases. J Neurosurg. 2004 Nov;101(5):846-53.
Harun et al in their recent eLetter [1] contend that I have failed to
understand their motivation. It is not the motivation that is being
questioned but the outcome of that motivation, i.e. the proposed
modification of the classification. The fact that they see the need to
modify the Roper-Hall classification [2] is in itself evidence that the
Roper-Hall classification does not entirely fulfil the p...
Harun et al in their recent eLetter [1] contend that I have failed to
understand their motivation. It is not the motivation that is being
questioned but the outcome of that motivation, i.e. the proposed
modification of the classification. The fact that they see the need to
modify the Roper-Hall classification [2] is in itself evidence that the
Roper-Hall classification does not entirely fulfil the purpose for which
it was designed in the context of modern day practice and indeed is
motivation enough to try and change it. Simplifying a classification is
commendable but not if the simplification has not been validated and is
unsubstantiated. The issue with the Roper-Hall classification is that it
lumps a wide range of injury in its final grade IV giving all a poor
prognosis. With modern treatments and approaches to management many
chemical injuries within the Roper Hall grade IV will today do well. Grade
IV injuries with total limbal involvement and total conjunctival
involvement will not, despite the recent advances in management. Hence the
clinical need is to expand, not contract grade IV, which is what the Dua,
King and Joseph Classification does [3]. To the contrary, the proposed
modification by Harun et al [4] further compounds the problem by combining
the Roper-Hall grades III and IV. It is essential to understand that the
Roper-Hall classification is a prognostic classification and one cannot
simply give the same prognosis to an eye with (more than) 6 clock hours of
affected limbus as to an eye with 12 clock hours of affected limbus (Roper
-Hall classification). It is even less conceivable therefore to give an
eye with 4 clock hours of affected limbus or 33% conjunctival involvement
the same prognosis as an eye with 12 clock hours of limbus involvement and
100% conjunctival involvement as is proposed by Harun et al [4].
Anatomically the conjunctiva is divided into tarsal (palpebral),
forniceal and bulbar areas. Harun et al [4] have emphasised the importance
of the forniceal conjunctiva in their original letter but have failed to
account for the forniceal conjunctiva in the calculation of the area of
conjunctiva involved. To quote from their original letter [4] “The bulbar
and tarsal conjunctiva comprise approximately two thirds and one third of
the total conjunctival surface respectively.” This contradiction is now
being addressed by implying that tarsal and bulbar conjunctiva together
include the forniceal conjunctiva! There are several other discrepancies
that were pointed out in my previous eLetter [5] which have not been
addressed.
Another discrepancy worth mentioning is that according to the Table in the
proposed modification [5] involvement of inferior bulbar and tarsal
conjunctiva (and forniceal) without any corneal or limbal involvement (OR
> 1/3 conjunctival involvement), will carry the same guarded prognosis
as involvement of the entire limbus and the entire conjunctiva!! This is
simply not the case.
The authors state that their proposed modification can be easily
remembered by all ophthalmologists and not just cornea specialists. I ask,
what can be more simple (and accurate) than recording clock hours of
limbus involvement and percentage of conjunctival involvement, as
indicated in the Dua, King and Joseph classification? Surely “all
ophthalmologists” would take exception to the suggestion that they need
something simpler than this.
Harminder S Dua
PS. This debate has stretched far enough and cannot continue without
becoming tediously repetitious. I have stated all that I had to and do not
intend responding to any further correspondence on any issue that has
already been covered thus far.
We thank Dr Madhusudhana for drawing our attention to an error in our recent publication.[1] The correct Venn diagram showing the distribution of retinal breaks in detached retina is available here as a PDF (printer friendly file).
Correct Venn Diagram
We thank Dr Madhusudhana for drawing our attention to an error in our recent publication.[1] The correct Venn diagram showing the distribution of retinal breaks in detached retina is available here as a PDF (printer friendly file).
Correct Venn Diagram
Reference
1. L Wickham, M Connor, and G W Aylward
Vitrectomy and gas for inferior break retinal detachments: are the results comparable to vitrectomy, gas, and scleral buckle?
Br J Ophthalmol 2004; 88: 1376-1379.
We have read with interest the manuscript “Multidrug resistant
proteins: P-glycoprotein and lung resistance protein expression in
retinoblastoma” by Krishnakumar S, Mallikarjuna K, Desai N, et al [1]. We
have studied 18 children with retinoblastoma using immunohistochemical
detection of P-glycoprotein by the mouse monoclonal antibody HYB-241 in
frozen section tumor samples. Like Krishnakumar et al, we...
We have read with interest the manuscript “Multidrug resistant
proteins: P-glycoprotein and lung resistance protein expression in
retinoblastoma” by Krishnakumar S, Mallikarjuna K, Desai N, et al [1]. We
have studied 18 children with retinoblastoma using immunohistochemical
detection of P-glycoprotein by the mouse monoclonal antibody HYB-241 in
frozen section tumor samples. Like Krishnakumar et al, we found limited
expression of P-glycoprotein in retinoblastoma cells since only four of
the 18 samples were positive. However, 6 of 18 samples had P-glycoprotein
positivity in tumor-associated endothelial cells. Contrarily to
Krishnakumar S et al, we had the opportunity of evaluating children that
received prior therapy with drugs that can be affected by P-glycoprotein
and no obvious difference in its expression was evident.
Only one of the three tumor samples coming from patients who had been
exposed to P-glycoprotein mediated chemotherapeutic agents (vincristine
and/or etoposide) were positive in retinoblastoma cells. In addition of
the 6 cases in which P-glycoprotein was detected in tumor-associated
endothelial cells, only one of them came from a patient who had been
exposed to P-glycoprotein mediated chemotherapeutic agents (etoposide).
Also, one patient whose tumor and tumor-associated endothelium were
negative had endothelial cells in the optic nerve that were positive. The
patient had not been exposed to P-glycoprotein mediated chemotherapy.
There is little information regarding its expression in normal eye
blood vessels, but P-glycoprotein expression has been detected in the
normal human retinal pigment epithelium and post laminar optic nerve [2]
and it is absent in the permeable microvessels of the choroid and the
ciliary process [3]. P-Glycoprotein expression in endothelial cells of
newly formed capillaries induced by tumors has also been described [4].
Its prognostic relevance in retinoblastoma is unknown, and it cannot be
determined form our data, since all of these eyes were already enucleated
and no patient suffered an extraocular relapse.
The potential role of P-glycoprotein in tumor-associated endothelium
creating a blood-tumor barrier is uncertain. Our results suggest that if
cyclosporine is indeed improving the efficacy of chemotherapy, it may be
acting by improving its delivery through P-glycoprotein expressing tumor-
associated endothelial cells or through altering pharmacokinetics of
chemotherapeutic drugs, rather than exclusively acting to reverse drug
resistance at the level of the tumor cell.
Our data do not support the hypothesis that cyclosporine will be a
useful adjunct to chemotherapy for the treatment of retinoblastoma via
competitive inhibition of P-glycoprotein in tumor cells.
Disclosure
There is no financial interest of the authors with any of the drugs and
devices mentioned.
References
(1) Krishnakumar S, Mallikarjuna K, Desai N, et al. Multidrug
resistant proteins: P-glycoprotein and lung resistance protein expression
in retinoblastoma. Br J Ophthalmol 2004;88:1521-1526.
(2) Kennedy B, Mangini N. P Glycoprotein expression in human retinal
pigment epithelium. Mol Vis 2002, 8, 422-430.
(3) Hofman P, Hoyng P, vander Werf F, Vrensen G, Schlingemann R. Lack
of blood-brain barrier properties in microvessels of the prelaminar optic
nerve head. Invest Ophthalmol Vis Sci 2001, 42, 895-901.
(4) Camassei FD, Arancia G, Cianfriglia M, et al: Nephroblastoma:
multidrug resistance P-glycoprotein expression in tumor cells and
intratumoral capillary endothelial cells. Am J Clin Pathol 2002, 117 (3),
484-90.
In the article presented by Wickham and associates,[1] the authors
compared vitrectomy and gas for treating inferior break retinal
detachments with vitrectomy, gas and scleral buckle. The study showed no
significant difference in the final outcome between the two groups. While
vitrectomy and gas for inferior break retinal detachments appears
promising, there are several issues that we would like to ra...
In the article presented by Wickham and associates,[1] the authors
compared vitrectomy and gas for treating inferior break retinal
detachments with vitrectomy, gas and scleral buckle. The study showed no
significant difference in the final outcome between the two groups. While
vitrectomy and gas for inferior break retinal detachments appears
promising, there are several issues that we would like to raise.
First, the surgery was performed by either a registrar, fellow or
consultant. These surgeons may have varying degrees of experience and the
inconsistency may affect the rate of successful surgical outcome. Second,
additional tears were treated with cryotherapy or laser. As shown by
Bonnet M et al,[2] the post-operative proliferative vitreoretinopathy (PVR)
rate could be as high as 25.8% in patients treated with cryotherapy as
compared to 2.2% in the laser group. It is unclear what the relative
distribution of patients who underwent cryotherapy in the two groups was
and this may have been a confounding factor in the study. Third, patients
underwent an air/gas exchange with either SF6 or C3F8. As C3F8 had a much
longer duration of tamponade than SF6, the use of one agent over another
may have lead to a difference in the success rate.
The study excluded patients with PVR grade C. However, for those with
grade A or B, a scleral buckle was planned before the operation. This
could lead to a selection bias where potentially more difficult cases were
scheduled into the scleral buckle group. This may be a contributing factor
for a higher rate of post-operative PVR (20%) and epiretinal membrane
formation in this group, compared to a rate of 5-10% reported previously.[3
-4] The underlying vitreo-retinal pathology rather than the placement of
the scleral buckle may have been a major reason behind the high PVR rate
noted in this group.
The authors stated that the main reasons for performing vitrectomy
and gas without scleral buckle was to avoid the possible complications of
scleral buckle, namely, longer operating time,[5] exposure, refractive
change, diplopia and anterior segment ischaemia.[6-10] Perhaps, in the
interest of readers, the authors can provide us with the information if
any of these complications developed during the study.
The high rate of final reattachment reported in the study is
encouraging. We believe that vitrectomy and gas alone is an effective
method to treat selected cases of retinal detachments with inferior
retinal breaks. A controlled, randomized, prospective study, comparing the
outcome in properly matched groups and with meticulous attention to
surgical methods [11] will help address some of the above issues and help
elucidate further if the procedure without the use of scleral buckle will
benefit patients with inferior break retinal detachment.
We would like to commend the authors for conducting this very nice
study on an important topic that may provide a better alternative
treatment. We wish that the issues that we raise will help broaden the
discussion on the topic.
Yolanda Y.Y. Kwong, MRCS
C.W. Tsang, MRCS
Wico W. Lai, MD, FACS
Dennis S.C. Lam, FRCS, FRCOphth
Hong Kong, People¡¦s Republic of China
The Corresponding Author has the right to grant on behalf of all
authors and does grant on behalf of all authors, an exclusive licence (or
non exclusive for government employees) on a worldwide basis to the BMJ
Publishing Group Ltd and its licensees, to permit this article (if
accepted) to be published in BJO and any other BMJPG products and to
exploit all subsidiary rights, as set out in our licence
(http://bjo.bmjjournals.com/misc/ifora/licenceform.shtml)
References
(1) Wickham L, Connor M, Aylward GW. Vitrectomy and gas for inferior
break retinal detachments: are the results comparable to vitrectomy, gas,
and scleral buckle? Br J Ophthalmol 2004;88:1376-1379.
(2) Bonnet M, Guenoun S. Surgical risk factors for severe postoperative
proliferative vitreoretinopathy in retinal detachment with grade B PVR.
Graefes Arch Clin Exp Ophthalmol 1995;233(12):789-91
(3) Charteris DG, Sethi CS, Lewis GP, Fisher SK. Proliferative
vitreoretinopathy ¡V developments in adjunctive treatment and retinal
pathology. Eye 2002;16:369-374.
(4) The Retina Society Terminology Committee. The classification of
retinal detachment with proliferative vitreoretinopathy. Ophthalmol
1983;90:121-125.
(6) Findall RJ, Norton EW, Curtin, et al. Reduction of extrusion and
infection following episcleral silicone implants and cryopexy in retinal
detachment surgery. Am J Ophthalmol 1971;71:835-7.
(7) Hayashi H, Hayashi K, Nakao F, et al. Corneal shape changes after
scleral buckling surgery. Ophthalmology 1997;104:831-7.
(8) Domniz Y, Cahana M, Avni I. Corneal surface changes after pars
plana vitrectomy and scleral buckling surgery. J Cataract Refract Surg
2001;27:868-72.
I would like to congratulate Theelen et al for their recent
article on impact factors on intraocular pressure measurements in healthy
subjects [1], and I would like to add a thought. As Theelen and colleagues
point out with reference to the literature [2,3], increased pressure in
the jugular vein leads to increased brain pressure, and by an increase in
the episcleral venous pressure, to an elev...
I would like to congratulate Theelen et al for their recent
article on impact factors on intraocular pressure measurements in healthy
subjects [1], and I would like to add a thought. As Theelen and colleagues
point out with reference to the literature [2,3], increased pressure in
the jugular vein leads to increased brain pressure, and by an increase in
the episcleral venous pressure, to an elevation of intraocular pressure.
Correspondingly, in a previous study by Teng and associates, it was
discussed that a tight necktie may increase intraocular pressure by an
increased jugular vein pressure and could affect the diagnosis and
management of glaucoma [4]. It may be taken into account, however, that
the brain pressure and pressure in the cerebrospinal fluid space
surrounding the retrobulbar part of the optic nerve are the counter-
pressure against the intraocular pressure across the lamina cribrosa [5].
If the cerebrospinal fluid space pressure is elevated (due to increased
jugular vein pressure), the intraocular pressure may also be allowed to be
elevated so that the trans-lamina cribrosa pressure difference may remain
constant. Independently of the question, whether a thight neck-tie may or
may not increase intraocular pressure, one may assume that if the
intraocular pressure gets higher due to an increased jugular vein
pressure, it may, at least partially, be balanced by an increase in brain
pressure, without increasing the risk for glaucoma.
References
(1) Theelen T, Meulendijks CFM, Geurts DEM, van Leeuwen A, Voet NBM,
Deutman AF. Impact factors on intraocular pressure measurements in healthy
subjects. Brit J Ophthalmology 2004; 88:1510-1.
(2) Mavrocordatos P , Bissonnette B, Ravussin P. Effects of neck position
and head elevation on intracranial pressure in anaesthetized neurosurgical
patients—preliminary results. J Neurosurg Anesthesiol 2000; 12: 10–4.
(3) Toole JF. Effects of change of head limb and body position on cephalic
circulation. N Engl J Med 1968; 279: 307–11.
(4) Teng C, Gurses-Ozden R, Liebmann JM, Tello C, Ritch R. Effect of a
tight necktie on intraocular pressure. Brit J Ophthalmology 2003; 87:946-
94
(5) Jonas JB, Berenshtein E, Holbach L. Lamina cribrosa thickness and
spatial relationships between intraocular space and cerebrospinal fluid
space in highly myopic eyes. Invest Ophthalmol Vis Sci 2004; 45: 2660-5.
Dear Editor,
We were highly interested by Sharma et al's paper on inferior-tear
retinal
detachment (RD) and we would like to make a few remarks.
Is there any significant difference between phakic and pseudophakic
patients ? When comparing the two techniques, it is worth reminding that
vitrectomy will systematically induce cataract within a few years, which
will imply secondary surgery. This will considerably increa...
Dear Editor,
We were highly interested by Sharma et al's paper on inferior-tear
retinal
detachment (RD) and we would like to make a few remarks.
Is there any significant difference between phakic and pseudophakic
patients ? When comparing the two techniques, it is worth reminding that
vitrectomy will systematically induce cataract within a few years, which
will imply secondary surgery. This will considerably increase management
costs.
We do not fully agree with the definition proposed for this particular
RD
group. According to Sharma et al, inferior-tear RD is characterised by
at
least one tear being localised between the 4- and 8-hour meridians.
Figure
2 is a good illustration of that, where all three sketches show tears
beyond the 3h-9h meridians. It is our view that inferior-tear RD can
only
be evoked when all tears are between 4 and 8-h meridians. Otherwise, it
is
not inferior-tear RD but rather superior-tear RD complicated by an
inferior tear. Consistently with this definition, inferior-tear RDs
appear
to induce a high risk of recurrence. Indeed, we found a significantly
increased risk of recurrence in such specific RD cases2.
We agree with Sharma et al when they underline the importance of
postoperative positioning following inferior-tear RD surgery. Several
processes have been used. We setup a prospective study in patients
operated on for inferior-tear RD by indentation, subretinal fluid
drainage
and gas injection. We systematically positioned a wire under the right
inferior so as to leave the eye under traction for a few days (photos).
Bed foot legs were also propped up to give the patient a feet-up
posture.
Our first results in 10 patients revealed 100% anatomical success with
subretinal fluid persistence for 3 months in one patient and we had to
reinject gas in another.
Management of inferior tear RD is specific and requires more studies
like
that of Sharma et al, to try and establish a consensus.
References
1. Sharma A, Grigoropoulos V, Wiliamson TH. Management of primary
rhegmatogenous retinal detachment with inferior breaks. Br J Ophthalmol
2004;88:1376-1379
2. Quintyn JC, Ponchel C, Fillaux J et al. A. Retinal detachment by
inferior tear, bad pronostic ? J Fr Ophtalmol to be published
Competing Interest Statement No authors have any competing financial interests.
We read with interest for the article by Raiskup et al. on the long
term evaluation on mitomycin C (MMC) for pterygium.[1] It seems that the
usage MMC in pterygium surgery is relatively safe in the long term.
Overdosge of MMC eyedrops may be associated with potential serous
side effects such as corneal perforation.[2] In this regards, we would like
to point out a major typo in the Abstr...
We read with interest for the article by Raiskup et al. on the long
term evaluation on mitomycin C (MMC) for pterygium.[1] It seems that the
usage MMC in pterygium surgery is relatively safe in the long term.
Overdosge of MMC eyedrops may be associated with potential serous
side effects such as corneal perforation.[2] In this regards, we would like
to point out a major typo in the Abstract. The dosage of the MMC
eyedrops should be 0.01% or 0.02% instead of 1% or 2%. Besides, we would
be appreciative if the authors could clarify the duration of MMC eyedrops
that was given postoperatively, whether it is a 2-week course as described
in the Abstract or a 5-day course as described in the Patients and
Methods.
Since a single intraoperative application of MMC and post operative
MMC eyedrops are equally effective, it seems that the former is the
treatment of choice as it is easier to administer and there is no
compliance issue.
Finally, the authors also suggested that at present, they advise the
use of MMC at a concentration of 0.02% intraoperatively for 3 minutes.
This, however, according to our experience, is associated with a higher
recurrence rate as compared with 0.02 % for 5 minutes (42.9% vs 8.3%).[2]
References
1. Raiskup F, Solomon A, Landau D, Ilsar M, Frucht-Pery J. Mitomycin
C for pterygium: long term evaluation. Br J Ophthalmol. 2004;88:1425-8.
2. Lam DS, Wong AK, Fan DS, Chew S, Kwok PS, Tso MO. Intraoperative
mitomycin C to prevent recurrence of pterygium after excision: a 30-month
follow-up study. Ophthalmology. 1998;105:901-4
We read with interest the article by Muhtaseb et al. on the
development of a system for preoperative stratification of cataract
patients according to their risk of intraoperative complications. [1] In their article the authors have analyzed
1441 cataract surgeries in order to determine factors that would
increase
the risk of surgical complications.
We read with interest the article by Muhtaseb et al. on the
development of a system for preoperative stratification of cataract
patients according to their risk of intraoperative complications. [1] In their article the authors have analyzed
1441 cataract surgeries in order to determine factors that would
increase
the risk of surgical complications.
We have previously described a similar simple grading system for
assessing the risk of cataract surgery which we called "the cataract
surgery risk score" and found it to be useful for residents and
beginning
surgeons.[2] Our risk score is composed of individual points attributed to
risk factors that are believed to increase complications during surgery.
The advantage of such a system is that it allows the selection of cases
from easy to more difficult ones, as the surgeon's skills improve. It
also allows the beginning surgeons to focus on important details in the
ocular examination that are often overlooked.
References
1. M Muhtaseb, A Kalhoro, and A Ionides. A system for preoperative stratification of cataract patients according to risk of intraoperative complications: a prospective analysis of 1441 cases. Br J Ophthalmol 2004; 88: 1242-1246.
2. Najjar DM, Awwad ST. Cataract surgery risk score for residents
and beginning surgeons. J Cataract Refract Surg. 2003 Oct;29(10):2036-7.
We read with interest the article by Gouws et al.[1] on the apparent
increased incidence of cystoid macular oedema (CMO) in
phacoemulsification
patients when trypan blue was used to stain the anterior capsule.
Trypan blue was commonly used in both anterior and posterior
segment
surgeries.[2-4] If trypan blue does cause macular toxicity, its risks
should
theoretically be higher when used...
We read with interest the article by Gouws et al.[1] on the apparent
increased incidence of cystoid macular oedema (CMO) in
phacoemulsification
patients when trypan blue was used to stain the anterior capsule.
Trypan blue was commonly used in both anterior and posterior
segment
surgeries.[2-4] If trypan blue does cause macular toxicity, its risks
should
theoretically be higher when used in posterior segment surgeries.
However,
studies on the use of trypan blue, both in the anterior[2,3] and
posterior[4,5] segments, did not show apparent toxicity.
Thus, it would be appreciated if the authors could clarify whether
other potential confounders were assessed in their study, including:
1. Other causes of CMO such as diabetes, uveitis and prostaglandin
use;
2. Operating time since photo-toxicity from the operative
microscope[6] per
se is a risk factor for CMO development. It appears that only operations
for patients in group B were performed by one surgeon, if operations for
patients in group A (with trypan blue use) were done by trainees, the
operative time is expected to be longer;
3. Whether all patients received a fundus examination with dilated
pupil
after the operation. If these were only performed in patients with sub-
optimal visual acuities, the incidence of CMO may be underestimated.
Finally, we concur with the authors' view that we should try all
means in terms of minimising any theoretical toxicities of trypan blue.
It
is our routine to actively remove trypan blue with the bimanual
irrigation
aspiration system as soon as the anterior capsule has been stained. It
is
very effective and the potential toxicities might be reduced.
References
1. Gouws P, Merriman M, Goethals S, Simcock PR, Greenwood RJ,
Wright
G. Cystoid macular oedema with trypan blue use. Br J Ophthalmol. 2004
Oct;88(10):1348-9.
2. Melles GR, de Waard PW, Pameyer JH, Houdijn Beekhuis W. Trypan
blue capsule staining to visualize the capsulorhexis in cataract
surgery.
J Cataract Refract Surg. 1999 Jan;25(1):7-9.
3. Dada VK, Sharma N, Sudan R, Sethi H, Dada T, Pangtey MS.Anterior
capsule staining for capsulorhexis in cases of white cataract:
comparative
clinical study. J Cataract Refract Surg. 2004 Feb;30(2):326-33.
4. Feron EJ, Veckeneer M, Parys-Van Ginderdeuren R, Van Lommel A,
Melles GR, Stalmans P. Trypan blue staining of epiretinal membranes in
proliferative vitreoretinopathy. Arch Ophthalmol. 2002 Feb;120(2):141-4.
5. Li K, Wong D, Hiscott P, Stanga P, Groenewald C, McGalliard J.
Trypan blue staining of internal limiting membrane and epiretinal
membrane
during vitrectomy: visual results and histopathological findings. Br J
Ophthalmol. 2003 Feb;87(2):216-9.
6. Donzis PB, DeBartolo DF, Lewen RM, May DR. Light-induced
maculopathy and cystoid macular edema. J Cataract Refract Surg. 1988
Jan;14(1):84-5.
Dear Editor
We thank Drs Madill and Ffytche for their interesting comments on our paper [1] and are grateful for the opportunity to respond to some of the issues raised. The first relates to possible variations in the prevalence rate of Charles Bonnet syndrome (CBS) in different populations, on which there is currently very little substantive data. We agree that additional population-based studies are necessary to d...
Dear Editor
Harun et al in their recent eLetter [1] contend that I have failed to understand their motivation. It is not the motivation that is being questioned but the outcome of that motivation, i.e. the proposed modification of the classification. The fact that they see the need to modify the Roper-Hall classification [2] is in itself evidence that the Roper-Hall classification does not entirely fulfil the p...
Dear Editor
We thank Dr Madhusudhana for drawing our attention to an error in our recent publication.[1] The correct Venn diagram showing the distribution of retinal breaks in detached retina is available here as a PDF (printer friendly file). Correct Venn Diagram
Reference
1. L Wickham, M Connor, and G W Aylward Vitr...
Dear Editor
We have read with interest the manuscript “Multidrug resistant proteins: P-glycoprotein and lung resistance protein expression in retinoblastoma” by Krishnakumar S, Mallikarjuna K, Desai N, et al [1]. We have studied 18 children with retinoblastoma using immunohistochemical detection of P-glycoprotein by the mouse monoclonal antibody HYB-241 in frozen section tumor samples. Like Krishnakumar et al, we...
Dear Editor
In the article presented by Wickham and associates,[1] the authors compared vitrectomy and gas for treating inferior break retinal detachments with vitrectomy, gas and scleral buckle. The study showed no significant difference in the final outcome between the two groups. While vitrectomy and gas for inferior break retinal detachments appears promising, there are several issues that we would like to ra...
Dear Editor
I would like to congratulate Theelen et al for their recent article on impact factors on intraocular pressure measurements in healthy subjects [1], and I would like to add a thought. As Theelen and colleagues point out with reference to the literature [2,3], increased pressure in the jugular vein leads to increased brain pressure, and by an increase in the episcleral venous pressure, to an elev...
Dear Editor, We were highly interested by Sharma et al's paper on inferior-tear retinal detachment (RD) and we would like to make a few remarks. Is there any significant difference between phakic and pseudophakic patients ? When comparing the two techniques, it is worth reminding that vitrectomy will systematically induce cataract within a few years, which will imply secondary surgery. This will considerably increa...
Dear Editor
We read with interest for the article by Raiskup et al. on the long term evaluation on mitomycin C (MMC) for pterygium.[1] It seems that the usage MMC in pterygium surgery is relatively safe in the long term.
Overdosge of MMC eyedrops may be associated with potential serous side effects such as corneal perforation.[2] In this regards, we would like to point out a major typo in the Abstr...
Dear Editor
We read with interest the article by Muhtaseb et al. on the development of a system for preoperative stratification of cataract patients according to their risk of intraoperative complications. [1] In their article the authors have analyzed 1441 cataract surgeries in order to determine factors that would increase the risk of surgical complications.
We have previously described a si...
Dear Editor
We read with interest the article by Gouws et al.[1] on the apparent increased incidence of cystoid macular oedema (CMO) in phacoemulsification patients when trypan blue was used to stain the anterior capsule.
Trypan blue was commonly used in both anterior and posterior segment surgeries.[2-4] If trypan blue does cause macular toxicity, its risks should theoretically be higher when used...
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