We read with interest the article on the use of Medpor lower
eyelid spacers by Tan et al. [1]. The article critically evaluates the
utility of this type of a spacer for retraction of the lower lid. We
would
like to raise a few pertinent issues which may assist in a better
understanding of this challenging entity.
In this article, the authors have not included the assessment of
horizontal lid...
We read with interest the article on the use of Medpor lower
eyelid spacers by Tan et al. [1]. The article critically evaluates the
utility of this type of a spacer for retraction of the lower lid. We
would
like to raise a few pertinent issues which may assist in a better
understanding of this challenging entity.
In this article, the authors have not included the assessment of
horizontal lid laxity in their preoperative evaluation of patients.
Preoperative assessment of horizontal lid laxity and the integrity of
the
Canthal tendons is vital for deciding the adjunctive procedure to be
undertaken. This could be in the form of a lid shortening procedure or
strengthening of the canthal tendons, which should ideally be performed
along with the primary procedure [2]. Otherwise the desired effect of
placing a spacer may not be achieved. Moreover, if it is done as a
secondary procedure, it may be complicated as it may need to be combined
with implant trimming or exchange.
Further, it has been mentioned in the article that the orbital
septum
was incised to allow the implant to slip behind the orbital rim in
downgaze, in cases where lid dynamicity was required. Here it needs to
be
emphasized that extra care should be taken for securely fixing the
implant to prevent its posterior migration, which could lead to a host
of
undesirable sequelae. We suggest that a non-absorbable suture with good
tensile strength such as Prolene should be used for fixating the implant
to the lower border of the tarsus. This would ensure a more permanent
and
stable fixation and minimize the chances of extrusion or migration of
the
spacer.
The authors have mentioned that some patients had had previous
procedures such as hard palate and scleral spacers to correct lower lid
retraction. It is a common clinical experience that a second or
subsequent
surgery is usually associated with a multitude of poor prognostic
factors.
It would be very interesting to know if the authors encountered any
special problems in this subset of patients due to prior cicatrization
or
increased weight and thickness of the lower lid which could reduce the
effectiveness of the Medpor spacer.
References
(1) Tan J, Olver J, Wright M, Maini R, Neoh C, Dickinson AJ. The use of
porous polyethylene (Medpor) lower eyelid spacers in lid heightening and
stabilisation. Br J Ophthalmol. 2004 Sep;88(9):1197-200.
(2) Patel BC, Patipa M, Anderson RL, McLeish W. Management of
postblepharoplasty lower eyelid retraction with hard palate grafts and
lateral tarsal strip. Plast Reconstr Surg. 1997 Apr;99(5):1251-60
I read with interest Buono et al's paper [1]. They describe in detail
the value of anti-coagulant therapy in the management of giant cell arteritis. The role of anti-platelet agents however is not considered.
It
has been known for a number of years that thrombocytosis [2] and platelet
hyper-reactivity [3] are features of giant cell arteritis. Experimental
studies have shown that aspirin effectively sup...
I read with interest Buono et al's paper [1]. They describe in detail
the value of anti-coagulant therapy in the management of giant cell arteritis. The role of anti-platelet agents however is not considered.
It
has been known for a number of years that thrombocytosis [2] and platelet
hyper-reactivity [3] are features of giant cell arteritis. Experimental
studies have shown that aspirin effectively suppresses the production of
interferon-gamma, essential for the development of an inflammatory
infiltrate within the vessel wall [4]. Therefore in addition to an anti-
platelet effect, aspirin therapy may reduce this infiltrate, and the
consequent severe luminal narrowing that Buono et al. decribe in their
patient. Moreover, a recent retrospective study of 166 patients has
shown
that cranial ischemic complications developed in only 3% of the aspirin-
treated patients, compared with 13% of the patients treated with steroid
alone [5]. Given this early evidence it makes intuitive sense to treat
patients with giant cell arteritis using a combination of steroids and
aspirin in the first instance. Clearly heparin therapy may still have a
role to play in patients with severe complications but aspirin therapy
should be considered as part of the initial therapy following
diagnosis.
References
(1)Buono LM,
Foroozan R, de Virgiliis M, Savino PJ. Heparin
therapy in giant cell arteritis
Br. J. Ophthalmol., Feb 2004; 88: 298 - 301.
(2) Foroozan R, Danesh-Meyer H, Savino PJ, Gamble G, Mekari-Sabbagh
ON,
Sergott RC. Thrombocytosis in patients with biopsy-proven giant cell
arteritis. Ophthalmology. 2002 Jul;109:1267-71.
(3) Riddle JM, Bluhm GB, Pitchford WC et al. A comparative study of
platelet reactivity in arthritis. Ann N Y Acad Sci. 1981;370:22-9.
(4) Brack A, Rittner HL, Younge CK et al. Glucocorticoid-mediated
repression of cytokine gene transcription in human arteritis-SCID
chimeras. J. Clin Invest 1997;99:2842-2850.
(5) Nesher G, Berkun Y, Mates M, Baras M, Rubinow A, Sonnenblick M.
Low
-dose aspirin and prevention of cranial ischemic complications in giant
cell arteritis. Arthritis Rheum. 2004 Apr;50:1332-7.
We read with interest the case reports by Peponis et al. on the role of
corticosteroids in fungal keratitis. It is important to remember are that all
antifungal drugs used in clinical practice are fungistatic. Hence while an
abrupt cessation of steroid usage in recently diagnosed fungal keratitis may
cause increased inflammation, continuation of steroids may cause fungi to
p...
We read with interest the case reports by Peponis et al. on the role of
corticosteroids in fungal keratitis. It is important to remember are that all
antifungal drugs used in clinical practice are fungistatic. Hence while an
abrupt cessation of steroid usage in recently diagnosed fungal keratitis may
cause increased inflammation, continuation of steroids may cause fungi to
penetrate deeper into the cornea. The antifungal drugs rate poorly and are toxic
to the corneal epithelium [1]. Steroid usage even in tapering doses will reduce
corneal immunity.
We concur with the authors' view that sudden cessation of topical steroids
may cause increased inflammation which was hitherto kept under control by the
steroid usage. We have experienced such cases in our practice much of which is
for a rural population. We still advise caution in continuation of steroid usage
after the diagnosis of fungal keratitis is confirmed.
References
(1) Forster, R. K. The diagnosis and management of keratomycoses. Arch
Ophthalmol 1975; 93:1134.
A recent report stated it might be prudent to delay paediatric
cataract surgery, at least for bilateral cases, until 4 weeks of age to
lower the risk of later glaucoma,[1] and this suggestion was fully
supported in an accompanying editorial [2]. Such a suggestion that could
have an impact on the practice patterns of ophthalmologists and
consequently the care of children with cataract should have stron...
A recent report stated it might be prudent to delay paediatric
cataract surgery, at least for bilateral cases, until 4 weeks of age to
lower the risk of later glaucoma,[1] and this suggestion was fully
supported in an accompanying editorial [2]. Such a suggestion that could
have an impact on the practice patterns of ophthalmologists and
consequently the care of children with cataract should have strong data to
back it. For the following reasons, the data presented in the report do
not seem to rise to that level.
First, as postcataract surgery glaucoma is often a delayed
complication, it is critical to know how long study patients were
followed; and aside from what can be inferred from the presented
statements and survival analyses, such data are not provided. Second,
study patients with glaucoma often presented with the isolated finding of
elevated intraocular pressure, but no mention is made of whether all study
patients were screened for glaucoma using intraocular pressure measurement
(or other means) at any time postoperatively, let alone for the duration
of follow-up. This is important given the challenges of detecting
glaucoma in young children, which the authors acknowledge. Ultimately,
glaucoma was diagnosed if a study clinician elected to treat for glaucoma;
but specific, reliable, and mutually agreed upon parameters for making the
diagnosis were not defined. Third, from a study design perspective, the
decision to include a subgroup of patients (those with persistent
hyperplastic primary vitreous) in the study solely on the basis of the
glaucoma frequency within that subgroup (as determined from a preliminary
analysis) is problematic. Fourth, while other risk factors aside from a
young age at surgery have been associated with the development of aphakic
glaucoma, such as microcornea and secondary membrane surgery, no mention
is made of whether any patients in the study had such features. It might
be assumed that patients with microcornea were excluded from the study
since patients with “other ocular malformations” were excluded; if this is
the case, however, it would seem unusual that the authors would elect to
include patients with persistent hyperplastic primary vitreous (who
generally have microphthalmos, not to mention other abnormalities). In
any case, no multivariable statistical technique was employed that would
take into account other important potential risks for glaucoma aside from
simply an early age at cataract surgery; without such a multivariable
analysis, the validity of the authors’ conclusions would rest on the
presumption that other potential risks for glaucoma aside from age at
surgery were equally distributed among all age groups studied. Fifth, the
study purports to compare the glaucoma frequencies among those patients
operated on in the first month of life to those operated on later during
the first year of life, yet relatively few patients were operated on after
3 months (and especially after 5 months) of age.
A review of presently available reports tends to implicate early
cataract surgery in the pathogenesis of aphakic glaucoma, but exactly what
“early” is has not been absolutely established. In their discussion, the
authors cite prior studies indicating a higher risk of glaucoma when
surgery is performed in the first month of life; these studies, as well as
others indicating a high risk of glaucoma extending up to a later age at
surgery or indicating no relationship to age at surgery at all, have been
briefly reviewed elsewhere [3]. In each of these prior studies, at least
one shortcoming from among the following limit the certainty of any
conclusion relating age at surgery for isolated cataract to later
glaucoma: limited follow-up, small sample size, inclusion of patients
with ocular anomalies aside from cataract that might independently
predispose to glaucoma, inclusion of patients operated on with various
techniques, and lack of information regarding whether all study patients
were actually screened for glaucoma.
A recent study on a large group of cataract patients who lacked other
ocular anomalies aside from microcornea, who were operated on with modern
and standard technique, who were all screened for glaucoma, and who all
had a minimum of 5 years’ postcataract surgery follow-up found that
glaucoma was frequent when the cataract surgery was performed during the
first 9 months of life (37% of 272 patients’ eyes), without seeming matter
if the surgery was performed earlier or later within this timeframe [3].
(Of further note, the frequency of glaucoma was 24% of 25 patients’ eyes
in a subgroup undergoing surgery in the first month of life [previously
unpublished data, Peter K. Rabiah, 2004].) Multivariable analysis
confirmed young age at surgery as a predictor of later glaucoma. Like all
studies on the subject, this study is not without its flaws, but along
with other available reports, it calls into question the usefulness of
delaying surgery until 4 weeks of age. Admittedly, this study may not
have been available to the report’s authors during their manuscript
preparation, though importantly was available to the writer of the
editorial.
The balance of available data does not clearly support a
recommendation to delay cataract surgery until 4 weeks, or even 6 weeks,
of age if the expectation is a reduced risk of later glaucoma; in fact, a
far longer delay might very well be required, in which case the problem of
amblyopia would then weigh more heavily. Further study is required to
learn the optimal time to perform cataract surgery on an infant, with an
important goal being to achieve the most favorable balance between the
risks of later glaucoma and amblyopia.
Sincerely,
Peter K. Rabiah, M.D.
The author has no relevant financial interest in the subject matter of this
letter or the article/editorial on which he comments.
References
(1) Vishwanath M, Cheong-Leen R, Taylor D, Russell-Eggitt I, Rahi J. Is
early surgery for congenital cataract a risk factor for glaucoma? Br J
Ophthalmol 2004;88:905-910.
(2) Lambert SR. Treatment of congenital cataract. Br J Ophthalmol
2004;88:854-855.
3 Rabiah PK. Frequency and predictors of glaucoma after pediatric cataract
surgery. Am J Ophthalmol 2004;137:30-37.
In Snir and co-workers’ recent article about term-time refraction
and
keratometry comparing premature babies with full-terms [1] it was
usefully
confirmed that prematures’ corneas generally had a higher dioptric
power [2
-4]. This suggests relatively ‘more foetal’ or ‘retarded in development’,
as
a probable effect of the radical pre-term sh...
In Snir and co-workers’ recent article about term-time refraction
and
keratometry comparing premature babies with full-terms [1] it was
usefully
confirmed that prematures’ corneas generally had a higher dioptric
power [2
-4]. This suggests relatively ‘more foetal’ or ‘retarded in development’,
as
a probable effect of the radical pre-term shift in environment. However,
I
have some further questions and general remarks.
First, I was amazed by the 88% appearance of ROP stage 1-2 in a
sample so dominated by big prematures, as indicated by the quite high
mean
values of 32.9 weeks for gestational age at delivery and a birth weight
of
1694 g. Against the purpose of the authors - to exclude the more frail
and
sick prematures - it characterises the sample as clinically loaded, but
why so very loaded when not that much pre-term?
Regarding refraction, the authors primarily gave mean values (and
SD). They observed a level of hypermetropia in prematures that was about
one dioptre lower than in full-terms, but no exact frequency of myopia
was
given. In a small sample a few outliers (e.g. a quite low number of eyes
with high myopia) can considerably affect the refractive mean value and
reduce it’s meaning. Median values were given as 1.5 and 2.9 D,
respectively, but lacked the range and refractive distribution. The
authors further did not comment on the difference in mean value as
numerically explained by the keratometry findings.
Kindly, I have been quoted several times, but the authors seem to
have missed what appears most relevant in the context [5,6]. At postnatal
age 5 weeks (averaging 2-3 weeks before term) 59% of 203 prematures in
the published Danish sample had myopic refraction, a frequency that was
reduced to 24% 10 weeks later. Foetal dimensions including a steeper
cornea and relative spherophakia probably explain the refractive values
that tended to be lower the more pre-term the exam of the infant. Thus,
in accord with the axial oculometric findings at that early age, myopia
in
prematures around term was mainly considered a physiological
phenomenon.5,6
My main objection is to emphasize that perinatal myopia
in prematures should not be confused with the concept of myopia of
prematurity (MOP), or the diagnosis of which an age level of at least
one year is required. As an example, in the article it was quoted from
Holmström et al [7]. that the frequency of myopia was 8% in 6-month-olds,
and 10% at age
2½ years. The latter figure, in particular, expresses that probably we
are
dealing with permanent myopia in ex-prematures, and this constitutes
what is generally perceived as MOP. The less concise presentation of
results in Snir and co-workers’ sample (given as a lower mean refractive
value only, at gestational age week 40) deals with myopia in prematures,
and not with MOP. Probably some of these cases will later prove not to
be transient - regardless of ROP or not - and thus possibly qualify for
the label, but only follow-up can confirm this. Myopia around term in
prematures is almost physiologic, and not (yet) myopia of prematurity.
Admittedly, the authors cautiously avoid discussing MOP, but
confusion is near at hand and the difference between the two early age
myopias should be stressed. For a more thorough oculometrically based
discussion of myopia and neonatal ocular growth patterns, please refer
to my previous article [8] and to a previous letter to the editor [9].
References
(1) Snir M, Friling R, Weinberger D, et al. Refraction and
keratometry
in 40 week old premature (corrected age) and term infants. Br J
Ophthalmol
2004; 88: 900-904.
(2) Inagaki Y. The rapid change of corneal curvature in the neonatal
period and infancy. Arch Ophthalmol 1986; 104: 1026-1027.
(3) Cook A, White S, Batterby M, et al. Ocular growth and refractive
error development in premature infants without retinopathy of
prematurity.
Invest Ophthalmol Vis Sci 2003; 44: 953-960.
(4) Repka MX. Refraction and keratometry in premature infants
(editorial). Brit J Ophthalmol 2004;88: 853-854
(5) Fledelius HC. Ocular features other than retinopathy of
prematurity in the pre-term infant. Acta Ophthalmol 1990; 68: 214-217.
(6) Fledelius HC. Pre-term delivery and the growth of the eye: an
oculometric study of eye size around term time. Acta Ophthalmol 1992;
suppl 204:10-15.
(7) Holmström G, el Azazi M, Kugelberg U. Ophthalmological long term
follow-up of preterm infants: a population based, prospective study of
the
refraction and its development. Br J Ophthalmol 1998; 82: 1265-71.
(8) Fledelius HC. Eye size, refraction, and ocular morbidity. An
ultrasound oculometry based review. Ultrasonography in ophthalmology 14,
Docum Ophthal Proc Ser 58, 1995: 39-47.
(9) Fledelius HC. Retinopathy and myopia of prematurity (letter to
the editor). Br J Ophthalmol 2000; 84: 937.
HANS C FLEDELIUS
University Eye Clinic, Rigshospitalet, 2100 Copenhagen Ø, Denmark
I read with great interest the letter published in the August issue
of BJO by Lee et al. [1]. It reports on the first child born after IVF and
harboring a unilateral retinoblastoma in the USA.
However, it should be noted that this reported child from the USA is
the eighth documented child (not the sixth as mentioned by the authors).
The first child ever observed was reported by our grou...
I read with great interest the letter published in the August issue
of BJO by Lee et al. [1]. It reports on the first child born after IVF and
harboring a unilateral retinoblastoma in the USA.
However, it should be noted that this reported child from the USA is
the eighth documented child (not the sixth as mentioned by the authors).
The first child ever observed was reported by our group in 2001. He had a
unilateral disease [2]. In 2002, a second child with bilateral disease was
documented in the Netherlands [3]. In 2004, five additional cases were
reported from the Netherlands (two with bilateral disease and three with
unilateral disease). In this paper, an estimated relative risk of 4.9 to
7.2 for an IVF born child in the Netherlands to develop retinoblastoma was
surmised [4].
The issue of the possible association of assisted reproductive
techniques (ART) with an increased risk of retinoblastoma has raised great
concern worldwide. The interest of this association is highlighted by the
fact that the expression of retinoblastoma in childhood is influenced by
epigenetics – a regulatory mechanism not involving DNA sequence which
could be affected by the various ART techniques.
In recent years, tens of thousands of children were born after ART.
However, not one single case of retinoblastoma was observed until 2001.
The possible reasons for this phenomenon were discussed [5]. Awareness
regarding the occurrence of retinoblastoma in ART-born children sparked by
our original observation of the first case in 2001 has probably been a
trigger for the unveiling of additional cases. Therefore, more cases are
to be expected in the near future.
Whether the increased number of observed cases indicates that ART-
born babies have a higher risk of developing retinoblastoma remains to be
carefully investigated. Nonetheless, a thorough prospective assessment of
the possible association between ART and retinoblastoma is mandatory.
Ongoing multicentre and multinational control studies will hopefully
provide the needed answers to this "thorny" but most crucial aspect of
ART. Till then, accurate accounting of previous observations is, of
course, a key factor for a better insight into these issues.
David BenEzra, Jerusalem, Israel.
References
(1) Lee I, Finger PT, Grifo JA et. al.
Retinoblastoma in a child conceived by in vitro fertilization
British Journal of Ophthalmology, 2004; 88:1098-1099.
(2) Anteby I, Cohen E, Anteby E, BenEzra D.
Ocular manifestations in children born after in-vitro fertilization
Archives of Ophthalmology, 2001;119:1525-1529.
(3) Cruysberg JR, Moll AC, Imhof SM.
Bilateral sporadic retinoblastoma in a child born after in vitro
fertilization
Archives of Ophthalmology, 2002;120:1773.
(4) Moll AC, Imhof SM, Cruysberg JR et. al. Incidence of retinoblastoma in
children
born after in-vitro fertilization.
Lancet, 2003; 361:309-310.
(5) BenEzra D.
In-vitro fertilization and retinoblastoma. Commentary
Lancet 2003; 361:273-274.
Lim, et al, report a large-scale effort to mix home plus health
center acuity screening in preschool children [1].
We are very encouraged by the work of Lim, et al, particularly concerning
the frequency of ocular symptoms in the Korean preschooler, the number of
children who were not dismissed from specified follow-up (presumed
amblyopia risk), and the inclusion of a simple, home-administered test for...
Lim, et al, report a large-scale effort to mix home plus health
center acuity screening in preschool children [1].
We are very encouraged by the work of Lim, et al, particularly concerning
the frequency of ocular symptoms in the Korean preschooler, the number of
children who were not dismissed from specified follow-up (presumed
amblyopia risk), and the inclusion of a simple, home-administered test for
which over 97% of children were able to pass. It is of high merit that
parents were carefully instructed to place tissue and tape over the non-
tested eye, though this does not preclude peeking if the parent is not
paying particular attention. Positive answers to the parental
questionnaire were not very specific for eye disease and therefore could
greatly increase societal cost if used as a screening modality.
We have a few points of clarification for these authors: How was the home
acuity test initially validated? Did a number of children who passed
their home exam have gold-standard confirmatory exams from which False
negative and True negative rates could be estimated?
The positive predictive value estimates utilize gold-standard exam
criteria that need further definition and/or standardization; 1) it is not
clear whether amblyopia was diagnosed at multiple eye clinics and by
general or pediatric ophthalmologists, it is not clear what criteria are
used to define amblyopia, and the criteria to be included as a
“significant” cycloplegic refractive error vastly over-estimates risk
factors compared to a recently published attempt to standardize reporting
of vision screening research [2].
We would urge the authors to perform additional calculations on the
breakdown of gold-standard exam “significant” refractive errors [2] and
better define how amblyopia was diagnosed.
Robert W. Arnold, M.D., James Ruben, M.D., Sean P. Donahue, M.D., Ph.D.
AAPOS Vision Screening Committee.
References
(1) Lim HT, Yu YS, Park SH, et al. The Seoul Metropolitan Preschool
Vision Screening Programme: results from South Korea. Br J Ophthalmol
2004;88:929-33.
(2) Donahue S, Arnold R, Ruben JB. Preschool vision screening: What should
we be detecting and how should we report it? Uniform guidelines for
reporting results from studies of preschool vision screening. J AAPOS
2003;7:314-315.
We thank Lenio S Alvarenga for his comment on our article about using
fibrin glue for pterygium surgery.
1. We write in the Material and Methods section that only the
thickened and keratinised portion of the conjunctiva was excised and the
graft was prepared to have the same size as the nasal conjunctival defect,
regardless which group the patient was randomized to. Thus the knowledge
of the...
We thank Lenio S Alvarenga for his comment on our article about using
fibrin glue for pterygium surgery.
1. We write in the Material and Methods section that only the
thickened and keratinised portion of the conjunctiva was excised and the
graft was prepared to have the same size as the nasal conjunctival defect,
regardless which group the patient was randomized to. Thus the knowledge
of the surgery method did not influence the results or conclusions of the
study. It is also impossible to randomize the patients without the
surgeon’s knowledge, because the grafts were handled somewhat differently
in the different methods described.
2. The fibrin adhesives in the references mentioned by Alvarenga are
clearly not Tisseel Duo Quick from Baxter: In the article by Hino et al,
the specific trade name of the fibrin sealant is not given, but the text
states that the sealant in question is treated by dry heat to inactivate
viruses - Tisseel is vapour-heated, so it cannot be Tisseel. In the
Kawamura et al article the product is Beriplast - Aventis Behring.
Nevertheless, we will pay attention to this matter in the future. We have
not been able to find any report of HPV B19 infection when fibrin glue was
used in minor surgery. To date we have used the fibrin glue in more than
700 eye procedures since 1999. Any clinical infection with HPV B19 has not
yet been detected in our patients.
It is interesting to read the attempt by Harun et [1] mounting a
robust defence of their purely theoretical modification of the Roper Hall
classification which has stood us well over the years but now takes its
proud place in history. In the penultimate paragraph of the recent eLetter
they contend that it is incorrect to state that their proposal is purely
theoretical as they "..have based it on a...
It is interesting to read the attempt by Harun et [1] mounting a
robust defence of their purely theoretical modification of the Roper Hall
classification which has stood us well over the years but now takes its
proud place in history. In the penultimate paragraph of the recent eLetter
they contend that it is incorrect to state that their proposal is purely
theoretical as they "..have based it on a widely accepted classification,
which has almost 40 years of clinical use." The point is that the Roper
Hall classification is widely accepted, their modification of it is purely
theoretical and not clinically tested. I do not see how they can justify
their modification by piggy backing on the very classification they are
trying to modify?
In their second eLetter they make the technical point that three
clock hours is 1/4 of limbal involvement and not 1/3rd. They miss the real
point however that any classification equating more than 1/3rd limbal
involvement with total (12 clock hours) limbal involvement and lumping
the entire range therein in one grade of III+, is inaccurate as a
prognostic indicator. They illustrate this flaw in paragraph four where
they claim that injuries involving more than 3 to 6 clock hours of the
limbus would be classified as Grade III (as would someone with 12 clock
hours of limbal involvement). To give an eye with just over 1/3rd limbal
damage and just over 1/3rd conjunctival damage the same "guarded"
prognosis (grade III+) as an eye with 12 clock hours of limbal damage and
total bulbar and forniceal conjunctival damage (also grade III+ in the
proposed modification [2])incorrect and unacceptable. The prognosis for
the latter is "very poor" not "guarded".
It is correct that The Roper Hall classification [3] did not take into
account conjunctival involvement in the same sense as is considered in the
Dua, King and Joseph classification [4] or indeed in the proposed
modification [2]. The Roper Hall classification refers to the limbus and
"contiguous conjunctiva" which implies the involvement of conjunctiva
adjacent to the limbus only. This is reflected in the table of the Roper
Hall classification where the word 'conjunctiva' only appears at the
heading of a column with no allowance made for including conjunctiva in
the actual grading of the burn. Harun et al, [1,2] make an important point
about the tarsal conjunctiva and clearly it is important to examine it in
every ocular burns patient. However, for the purpose of the classification
it does not make any material difference, as in my experience I have never
encountered a case of tarsal burn without associated bulblar and/or
foniceal conjunctival involvement. I would be interested to know if the
Harun et al have. They imply that the Dua, King and Joseph
classification [4] does not take into consideration forniceal involvement.
This is not correct. In the original paper [4] a whole paragraph is devoted
to his aspect. Harun et al in their original letter [2] distinguish
between bulbar forniceal and tarsal conjunctiva and the mucocutaneous
junction emphasising the importance of the latter two. Why then in their
proposed modification do they not take into account the latter two? In
paragraph six of the original letter [2] they account for one hundred
percent of the conjunctival surface by divvying up the bulbar and tarsal
conjunctiva. What about the forniceal conjunctiva, where the stem cells of
the conjunctival epithelium are believed to reside [5,6]. Why is this not
accounted for in the modification?
Harun et al [1] state that "Dua also misinterprets the quantification
of corneal damage. He admits that corneal haze is an indicator of severity
of injury and of the offending chemical..." They have clearly misquoted
me on this. Neither in the original paper nor in my response to their
first letter have I stated the above. On the contrary I have stated that
"Corneal haze can be an indicator of the offending chemical rather than
the severity of the insult." Corneal haze or lack thereof can be very
varying and misleading especially soon after a chemical insult.
In Harun et al's proposed modification [2] the confusion is confounded
because the table is not consistent with the text that supports it. In the
table grade III+ equates to Hazy cornea OR >1/3 limbal ischaemia OR
>1/3 conjunctival involvement. The text states "Grade III includes
either a hazy cornea....and/or greater than one third of limbal or
conjunctival damage." This begs the questions: What is the difference
between III+ and III? Is "or" the same as "and/or"? to most people it
isn't. Will greater than 1/3 conjunctival damage without limbal damage
carry the same prognosis (as implied in the proposed modification) as
greater than 1/3 conjunctival damage with more than 1/3 limbal damage? In
their arguments they make a case, for retaining the term "ischaemia" over
"involvement" yet use the terms "ischaemia", "involvement" and "damage"
interchangeably through the text for both limbus and conjunctiva. For
example "Grade II includes limbal or conjunctival involvement, but
involving less than one third of the area involved" [2]. Furthermore, what
is "... Involving less than one third of the area involved" supposed to
mean?
The authors allege that the Dua, King and Joseph classification [4] is
"..a complicated semi-analogue sub-classification." Here again it is
likely that they have misunderstood the classification. The table in the
paper [4], as has been adequately explained by the supporting text, refers
to a stepped graded classification, consistent with past and current
systems, in the left hand columns and to an analogue scale (which one may
prefer to call semi-analogue) in the right hand columns. On balance, in
the paper, the analogue scale is recommended.
What can be more simple than documenting the clock hours of limbus
involvement and percentage of conjunctival involvement (tarsal conjunctiva
included or not) as a true representation of the extent of damage
following a chemical burn? These two are the key indicators of the
eventual prognosis in terms of ocular surface reconstruction and visual
improvement thereof. Even an attempt to put these into grades I to III or
IV or VI would be superfluous as that is merely a 'lumping' exercise. For
the purpose of any study or comparison, the documentation of clock hours
of limbal involvement and extent of conjunctival involvement, whether in
proportions or percentages, as accurately as possible will allow
subsequent groupings tailored to address the question posed.
The authors end with a profound statement "Without good evidence to
the contrary, it would be irresponsible to disregard a widely accepted
grading system." Unfortunately it applies aptly to their proposed
modification.
References
(1) Harun S, Srinivasan S, Hollingworth K, Batterbury M, Kaye SB.
Classification of ocular chemical injuries, continued BJO second eLetter
(13 July 2004)
(2) Harun S et al. Modification of classifiaction of ocular chemical
injuries [electronic response to Dua et al. A new classification of ocular
surface burns] bjophthalmol.com 2004
http://bjo.bmjjournals.com/cgi/eletters/85/11/1379#219
(3) Roper-Hall MJ. Thermal and chemical burns. Trans Ophthalmol Soc UK
1965;85:631-53
(4) Dua HS, King AJ, Joseph A. New Classification of Ocular surface
burns. Br J Ophthalmol 2001; 85:1379-83
(5) Wei Z-G, Cotsarelis G, Sun T-T, Lavker RM. Label-retaining cells
are preferentially located in the forniceal epithelium: implications on
conjunctival epithelial homeostasis. Invest Ophthalmol Vis Sci 1995;36:
236-46.
(6) Pellegrini G, Golisano O, Paterna P et al. Location and clonal
analysis of stem cells and their differentiated progeny in the human
ocular surface. J Cell Biol 1999;145:769-82.
The work by Habib et al [1] is a timely one with the increasingly
important role of assessment and monitoring of the quality of health
service delivery and outcomes. As they indicate, little work exists in
ophthalmology on the associations between surgical volume and outcomes.
This may partly be due to the low rate of serious complications with
ophthalmic surgery such as cataract extraction. However...
The work by Habib et al [1] is a timely one with the increasingly
important role of assessment and monitoring of the quality of health
service delivery and outcomes. As they indicate, little work exists in
ophthalmology on the associations between surgical volume and outcomes.
This may partly be due to the low rate of serious complications with
ophthalmic surgery such as cataract extraction. However, with large
numbers of patients undergoing cataract surgery, ophthalmologists cannot
afford to become complacent as even relatively low complication rates have
the potential to harm many in the community. Currently, in Western
Australian hospitals, phacoemulsification with intraocular lens insertion
is the most commonly performed surgical procedure.
The lack of significant associations between an individual surgeon’s
surgical volume and complication rate in contrast to that shown for the
pooled data [1] may be due to less statistical power in the former group
and is a limitation with any single centre study. Our population-based
work into endophthalmitis after cataract surgery showed marked differences
in endophthalmitis incidence across different surgical centres. However,
we did not find any association between cataract surgery volume and
endophthalmitis risk either before [2] or after adjustment for case-mix
[3].
These contrasting results highlight the importance of selecting valid
outcome measures when the monitoring of clinician performance is being
considered. Should we choose a surrogate measure, a clinical endpoint or
both? The degree to which any complication is within the control of the
surgeon will vary. If a complication is multifactorial, such as
endophthalmitis, then the entire system of care is just as important as a
surgeon’s technical expertise.
Despite highly publicised failures of care [4], it is important that
we do not succumb to a simplistic populist model of “someone to blame”.
Although monitoring surgeon performance is an important aspect of any
quality improvement effort, equally important is a better understanding
and attention to the operating environment and prevailing organisational
culture.
References
(1) Habib M, Mandal K, Bunce CV, Fraser SG. The relation of volume
with outcome in phacoemulsification surgery. Br J Ophthalmol 2004;88:643-
646.
(2) Morlet N, Li J, Semmens JB, Ng J. The Endophthalmitis Population
Study of Western Australia (EPSWA): First Report. Br J Ophthalmol
2003;87:574-576.
(3) Li J, Morlet N, Ng JQ, Semmens JB, Knuiman MW. Significant
nonsurgical risk factors for endophthalmitis after cataract surgery: EPSWA
fourth report. Invest Ophthalmol Vis Sci 2004;45:1321-1328.
(4) Smith R. One Bristol, but there could have been many. BMJ
2001;323:179-180
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The work by Habib et al [1] is a timely one with the increasingly important role of assessment and monitoring of the quality of health service delivery and outcomes. As they indicate, little work exists in ophthalmology on the associations between surgical volume and outcomes. This may partly be due to the low rate of serious complications with ophthalmic surgery such as cataract extraction. However...
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