I read with great interest your case report on the leech bite to the eye sustained by a 4 year old girl in Germany - in particular that
infestation of the human eye is very rare (“To our knowledge only one case
is described in the literature”). While this may indeed be the case in
Europe, here in Tasmania, the southernmost state of Australia, this event
is evidently much more common and occasions a lot...
I read with great interest your case report on the leech bite to the eye sustained by a 4 year old girl in Germany - in particular that
infestation of the human eye is very rare (“To our knowledge only one case
is described in the literature”). While this may indeed be the case in
Europe, here in Tasmania, the southernmost state of Australia, this event
is evidently much more common and occasions a lot less excitement on the
part of health professionals.
My experience of this occurred in January 2004 as I was bushwalking
in the Cradle Mountain- Lake St Clair National Park. Leeches are quite
common in the Tasmanian bush. They are land leeches and in some places in
wet conditions can be in plague proportions. However in dry summer
weather they are relatively uncommon. On the 5th day of our walk my
daughter and I were climbing a pass at 1100 metres in a snowstorm when a
flurry of snow blew into my right eye and with it something dark and
rather large. When I couldn’t readily dislodge it, I called my daughter
over and she identified it as a leech, very firmly attached and biting
through the white of my eye.
The recommended ways of detaching leeches are to either apply salt or
a flame, but we had no salt with us and had no intention of applying a
flame near the eye. I toyed with the idea of using a solution of fruit
saline to the eye, but wasn’t sure exactly what was in it and was loathe
to risk harm to the eye with an unknown substance. The other way of
getting rid of leeches is to irritate them with a gentle rubbing motion
until they drop off - one is always counselled not to just pull them off.
None of these options seemed possible. In a matter of minutes the
leech had inveigled itself so that only its head was visible at the inner
corner of my eye, its tail just visible at the outer corner and its body
totally inaccessible up under my upper eyelid. I briefly entertained the
notion of letting it stay there until it had fed and dropped off, but its
proximity to my tear duct began to worry me, given the speed with which it
had already made itself at home. In the end I irritated it until it
detached its back end and once I got a fair grip on it made one of those
split second decisions - and yanked.
The eye bled profusely and I packed it with snow. However, as we
dropped to lower altitudes, snow was no longer available and bleeding
recommenced. By the time I reached a hut that afternoon the tissue around
the eye was noticeably swollen and the eye itself was very bloodshot. The
next morning (Monday) it looked worse rather than better so we set off
to walk the 32 kilometres north to the nearest road, in order to get the
eye seen to as soon as possible. We acquired salt from another walker and
I bathed the eye with a saline solution several times during the day, in
an effort to avoid infection. We got out of the bush by midday on Tuesday,
but by the time we had driven the 400km to Hobart it was evening so
doctors and ophthalmologists were largely unavailable and I ended up
seeing a locum general practitioner at an After Hours clinic. He was new
to Tasmania and hadn’t seen a similar case, so he conferred with the
casualty section of the local hospital, but they really just confirmed his
initial advice to me.
We all agreed there appeared to be no vision problems involved. If I
had cared to queue up at the hospital for 3-4 hours I could have been
checked out for corneal erosion, but I didn’t bother as the doctor and I
were both pretty sure I didn’t have any. The doctor assured me that the
subconjunctival bleeding (the white of my eye was entirely red) would
disappear in 2 -3 weeks and in the event it took only 5 days for it to do
so. As I was planning to return to the bush almost immediately I was
prescribed Chloromycetin eye ointment to use in the event of the eye
becoming infected, which didn’t occur. I was told that there was no need
to see an eye specialist as there was nothing they could do.
Having been largely reassured by this visit, I thought I’d just check
out the internet with leech/bite/eye where, amongst others, I found your
journal reference and thought you might be interested in a related
experience.
I read with interest the article entitled "Conjunctival dendrite in a case of primary herpes simplex infection", (U Sridhar et al.[1] This is a very interesting and helpful clinical observation. The authors state that "appearance of a dendritic ulcer on
the conjunctiva, to the best of our knowledge, has not been reported".
We have previously published "Three cases of dendritic herpetic
ul...
I read with interest the article entitled "Conjunctival dendrite in a case of primary herpes simplex infection", (U Sridhar et al.[1] This is a very interesting and helpful clinical observation. The authors state that "appearance of a dendritic ulcer on
the conjunctiva, to the best of our knowledge, has not been reported".
We have previously published "Three cases of dendritic herpetic
ulcerations of the conjunctiva",[2] I would like to give that information to your readers.
References
1. U Sridhar, Y Bansal, S Choudhury, and A K Gupta. Conjunctival dendrite in a case of primary herpes simplex infection. Br J Ophthalmol 2004; 88: 590-591.
2. J Colin et al. Three cases of dendritic herpetic
ulcerations of the conjunctiva. Am J Ophthalmol
1980;89:608-609.
The importance of standardizing postoperative corneal thickness
measurements is important for many reasons. At what juncture post
operatively did the authors sample postoperative pachymetric measurements?[1]
The OrbScan utilizes scanning slit technology that is unpredictably
influenced by optically sensitive interface changes in the early
postoperative healing phase in some lasik patients. In th...
The importance of standardizing postoperative corneal thickness
measurements is important for many reasons. At what juncture post
operatively did the authors sample postoperative pachymetric measurements?[1]
The OrbScan utilizes scanning slit technology that is unpredictably
influenced by optically sensitive interface changes in the early
postoperative healing phase in some lasik patients. In these postoperative
patients (with normal slit lamp biomicroscopy), there is light scatter
from the cornea causing a falsely evaluated posterior float and
concomitant falsely thin pachymetric reading. The ultrasound pachymetric
reading however show a significantly different picture and is in line with
the performed treatment parameters. These initial OrbScan errors may be
linked with the patients’ early perception of haze. Repeat OrbScan
measurements months post operatively in these corneas show resolution of
the thinning/posterior float artifact, which may be commensurate with
histo pathologic healing process. Concomitancy some patients may have a
decreased perception of haze over this juncture. Perhaps what in reality
was post lasik cornea scatter resolution, has been mislabeled as “cortical
adaptation.”
References
1. K Kawana, T Tokunaga, K Miyata, F Okamoto, T Kiuchi, and T Oshika. Comparison of corneal thickness measurements using Orbscan II, non-contact specular microscopy, and ultrasonic pachymetry in eyes after laser in situ keratomileusis. Br J Ophthalmol 2004; 88: 466-468.
We read with interest the letter by Prakash et al.[1] concerning
residual cortical lens matter in the anterior chamber after
phacoemulsification. This was noted ten days post-operatively and was
promptly removed to alleviate a secondary rise in intraocular pressure
(IOP). We would like to share our experience of an unusual case of
retained lens matter presenting thirteen months post phacoemulsif...
We read with interest the letter by Prakash et al.[1] concerning
residual cortical lens matter in the anterior chamber after
phacoemulsification. This was noted ten days post-operatively and was
promptly removed to alleviate a secondary rise in intraocular pressure
(IOP). We would like to share our experience of an unusual case of
retained lens matter presenting thirteen months post phacoemulsification.
A 77-year old male patient presented with slight blurring of vision
and photophobia in the right eye, thirteen months after undergoing
uncomplicated phacoemulsification with posterior chamber intraocular lens
implantation (Acrysof SA60). His visual acuity was 6/12 in this right eye
and he had 1+ cells in the anterior chamber with no evidence of synechiae
and a normal IOP. Posterior segment examination was unremarkable. A
presumptive diagnosis of recurrent post-operative uveitis was made and he
was treated with a course of topical corticosteroids. However, at his
follow up visit three weeks later, his condition had not improved.
Examination now revealed corneal oedema localized inferiorly and a small
piece of residual nuclear lens matter was now evident in the anterior
chamber, which had not been noted initially. This fragment of 1 mm by 1mm in size was seen lodged between the inferior iris and the cornea. A day
later it was surgically removed under topical anaesthesia. Two weeks later
the visual acuity had improved to 6/9 and the corneal oedema as well as
the anterior chamber activity had resolved completely.
Retained nuclear or cortical lens matter after phacoemulsification
tends to present in the first few weeks following surgery and can cause a
more pronounced uveitis, corneal oedema, intraocular pressure rise and/or
cystoid macula oedema.[2] However, presentation although rare has been
reported as late as 5 months postoperatively.[3] To our knowledge, this is
the first case to present with this specific complication 13 months
postoperatively. We presume the mechanism to be initial entrapment of the
residual lens matter in the ciliary sulcus at a very peripheral location.
This would be followed by gradual migration of the fragment towards the
pupil facilitated by iris contraction/dilation movements and eventually
into the anterior chamber giving rise to symptoms. Meticulous technique
and a careful survey for any retained lens material at the time of surgery
is essential in preventing such complications. One must also consider this
possibility in post operative patients presenting with recurrent uveitis
even many months after the initial operation.
References
1. Prakash G, Kumar A, Purohit A. Unusual case of residual cortical
lens matter in anterior chamber. Br J Ophthalmol. 2003 Nov;87(11):1421.
2. Coombes A and Gartry D. Postoperative complications. In: Cataract
Surgery 1st ed. BMJ, 2003:168,172.
3. Bohigian GM, Wexler SA.Complications of retained nuclear fragments in
the anterior chamber after phacoemulsification with posterior chamber lens
implant. Am J Ophthalmol. 1997 Apr;123(4):546-7.
As cataract surgeons move toward toward less invasive procedures
including topical anesthesia, Friedman et al.[1] have done a research on
the patient's perspective.
Their results surprisingly showed that
patients preferred retrobulbar blockade anaesthesia over topical
anaesthesia in preparing for cataract surgery, raising the question
whether ophthalmologists are moving in the proper dir...
As cataract surgeons move toward toward less invasive procedures
including topical anesthesia, Friedman et al.[1] have done a research on
the patient's perspective.
Their results surprisingly showed that
patients preferred retrobulbar blockade anaesthesia over topical
anaesthesia in preparing for cataract surgery, raising the question
whether ophthalmologists are moving in the proper direction. However,
for informed consent patients need to be told not only the risks and
benefits of the cataract surgery itself but also the risk and benefits
of the alternative anesthesia modalities.[2] While rare, complications
of retrobulbar anesthesia injection can be devastating; for example,
inadvertent globe perforation,[3] blindness from the injection into the
optic nerve,[4] or apnea resulting from subarachnoid injection of the
anaesthetic agent.[5-6] Had the patients been informed of these uncommon
but serious complications, their preferences might have been altered and
the study results might have been different.
In our paper entitled "Can fixation instability improve text
perception during eccentric fixation in patients with central scotomas?",[1]
we reported that patients with eccentric fixation can improve their
perception of a text by performing rapid eye movements back and forth
between two eccentric retinal areas, thus inducing a revival of
eccentrically projected images. An experimental set-up allowed us...
In our paper entitled "Can fixation instability improve text
perception during eccentric fixation in patients with central scotomas?",[1]
we reported that patients with eccentric fixation can improve their
perception of a text by performing rapid eye movements back and forth
between two eccentric retinal areas, thus inducing a revival of
eccentrically projected images. An experimental set-up allowed us to
reproduce the perceptual phenomenon and the refixational eye movements in
normal subjects. These subjects reported that a change in fixation
position induced a refreshment of the letter image, immediately after the
realisation of the eye movement. Improved perception lasted approximately
one second. When fixation was maintained stable, a rapid fading effect was
noted which reduced letter recognition. This suggested that performing
refixational eye movements counteracts the occurrence of a form of
perceptual filling-in, known as Troxler’s phenomenon.
We recently examined a patient with bilateral central scotomas and
eccentric fixation who reported that blinking enabled him to refresh the
projected image. This observation added to our understanding of mechanisms
counteracting Troxler’s phenomenon. Moreover, it may have useful practical
implications in rehabilitation procedures for low vision subjects.
Therefore we believed this finding deserves to be briefly reported.
Case report
We investigated the reading strategies of a 44 year old man with
bilateral central scotomas of about 20 degrees in diameter. His visual condition
resulted from Stargardt’s disease, diagnosed at the age of 18. Visual
acuity was 0.08 in the right eye and, 0.1 in the left eye. A Scanning
Laser Ophthalmoscope (SLO, Rodenstock, Munich, Germany) was used to
project letters, words and a paragraphed text onto his retina and to
assess his fixation behaviour. We also asked the patient to read word of
different length on a monitor.
We observed that while deciphering words he blinked in a voluntary
and repetitive manner. He was aware of the phenomenon and he explained
that blinking helped him to read because it induced a revival of word
image. He developed the habit of blinking more frequently when he could
not immediately read the presented text.
This phenomenon can be reproduced using the set up described in our
above-mentioned study by maintaining fixation on a dot and rapidly
blinking when the letter fades.
Comment
Our observations demonstrated the occurrence of two distinct clinical
mechanisms counteracting fading of letters projected onto peripheral
retina. The first consists of repeated changes of fixation whereas the
second relies on repeated blinking. Both mechanisms involve intermittent
suppression of letter projection on the concerned retinal area. Our
findings corroborate a previous report emphasizing the influence of
temporal variations of the visual stimulus on perceptual filling-in.
Experimentally, normal individuals observe reduction of the filling-in
process when exposed to a flickering background (de Weerd et al., 1995).
This phenomenon should be kept in mind by low vision therapists when
rehabilitating patients who report difficulties in distinguishing
eccentrically located images.
Reference
(1) A Déruaz, M Matter, A R Whatham, M Goldschmidt, F Duret, M Issenhuth, and A B Safran. Can fixation instability improve text perception during eccentric fixation in patients with central scotomas? Br J Ophthalmol 2004; 88: 461-463.
We read with interest the article by Elder and Suter about what
patients would like to know before having cataract surgery.[1] We
congratulate the authors on investigating an area that has obviously been
overlooked in ophthalmology. However we feel they failed to recognise some
unique aspects of our specialty and also think that the nature of their
study limits its practical application.
We read with interest the article by Elder and Suter about what
patients would like to know before having cataract surgery.[1] We
congratulate the authors on investigating an area that has obviously been
overlooked in ophthalmology. However we feel they failed to recognise some
unique aspects of our specialty and also think that the nature of their
study limits its practical application.
Firstly, one area that we feel is all too often left out of
discussions with patients prior to cataract surgery is the intended
refraction. The fact that the authors did not ask if patients would like
to be informed of this supports our suspicions. Many patients may not even
know that the surgeon can choose their focusing distance. Contact lens
wearers with a unilateral cataract may like to decide if the refractive
status of both eyes should remain the same or if the operated eye should
be emmetropic so that they only have to wear one contact lens. Some
patients may be interested in monovision, which has been highly successful
in self-selected patients [2] and is easily remedied with spectacles if
patients cannot tolerate it. Unlike many other areas of surgery, cataract
surgery has an additional functional and cosmetic side to it that we feel
patients need to have some awareness of before they can give their
informed consent to the operation.
The authors chose to analyse differences between male and female
patients. The purpose of doing this was not given in the aims, and we fail
to see any useful application of this information. Would it not have been
of more use to analyse the views of one-eyed patients who are putting all
their good vision on the line? It would seem sensible to provide
information at a level that satisfies those patients that have the most to
lose.
We also feel that the very nature of their study makes it difficult
to draw conclusions. Are patients indeed aware of just how many different
complications there are that have a 1 in 10,000 chance of occuring? Are
they really interested in the details of expulsive choroidal haemorrhage,
uveitis-glaucoma-hyphaema syndrome, or prolonged hypotony due to an
inadvertent persistant filtering bleb? Would they want to know about a
risk if it is less than background rates of visual loss? We currently give
patients an information leaflet that includes an estimate of the chance of
visual loss then broadly explains the types of complications that can
occur. We suspect that were we to produce written information detailing
all complications that occur with a frequency of 1 in 10,000 that many
patients, if asked, would prefer our original leaflet. As such, and until
a well thought out study is done that shows otherwise, we will continue to
provide this same amount of risk information to patients.
References
1. Elder MJ, Suter A. What patients want to know before they have cataract
surgery. Br J Ophthalmol 2004;88:331-2.
2. Greenbaum S. Monovision pseudophakia. J Cataract Refract Surg
2002;28:1439-43.
We read with interest the report of Hsuan et al.[1]
The authors present a case series of 55 patients with
basal cell carcinoma on the eyelids. There are no details regarding the
size or histologic subtypes of basal cell carcinoma in the results and
therefore it is difficult to assess the applicability of the results to
other groups of patients who may have more or less severe basal cell...
We read with interest the report of Hsuan et al.[1]
The authors present a case series of 55 patients with
basal cell carcinoma on the eyelids. There are no details regarding the
size or histologic subtypes of basal cell carcinoma in the results and
therefore it is difficult to assess the applicability of the results to
other groups of patients who may have more or less severe basal cell
carcinoma. The authors make several generalizations regarding Mohs
surgery that we believe are unsubstantiated and we wish to take the
opportunity to clarify a few points.
1. The essence of Mohs micrographic surgery is 100% histologic frozen
section margin control. There is no other technique that enables 100%
margin examination, including the authors’ breadloaf section technique.
Mohs micrographic surgery has 99% five-year cure rates for basal cell
carcinoma because of the thorough margin examination. In distinction,
standard breadloaf section technique examines approximately 0.1% of the
surgical margin, with an increased potential to miss infiltrative tumor
extensions. Because the breadloaf technique is least likely to accurately
detect a positive margin, many surgeons employ a tangential peripheral
section analysis as a means of obtaining more through examination of the
margin.
2. Mohs micrographic surgery has another advantage, which is true
tissue sparing. The margin of normal skin removed during Mohs
micrographic surgery may be as little as one-half of 1 millimeter. When
operating on the eyelid, 1 millimeter can be the difference between
sacrifice and preservation of a critical structure (i.e. punctum). The
authors sacrificed 2 millimeters on both sides of the skin cancer, which
in some cases may have resulted in up to 3 millimeters of unnecessary skin
removal. This could result in more complicated reconstruction for
patients.
3. The authors state that their patients were happy to have multiple
operative sessions. For patients undergoing Mohs micrographic surgery,
complete tumor removal is accomplished in one session, with reconstruction
performed on the same day as tumor extirpation. The inconvenience to
patients associated with staged re-excision after 48 hours of histologic
examination and then a final stage reconstruction 48 hours after the last
histologic sample is taken should not be underestimated. Patients in
general are pleased with their care based primarily with their interaction
with the physicians. However, I sincerely doubt that any patient would
choose three surgical interventions over five days rather than one
surgical intervention with 100% margin control in one day.
4. The authors state that Mohs surgery is "too expensive". This
statement is unsubstantiated. In a cost analysis by Cook and Zitelli,[2]
Mohs surgery was found to similar in cost to excisional surgery and less
expensive than frozen section analysis. With three potential operative
encounters, the cost of staged excision of basal cell carcinoma in the
United States would exceed that for Mohs micrographic surgery with
reconstruction on the same day. It is also important to note that the
pathologic charges are included in the Mohs surgery fee, as the Mohs
surgeon functions as both the surgeon and pathologist. Therefore,
pathology charges generated for multiple staged re-excisions must be
included in any calculation of cost associated with staged excision.
5. The authors characterized Mohs surgery as "laborious". I would
argue that one doctor performing a very efficient tissue sparing operation
all in a matter of two to four hours, a typical duration for Mohs surgery
and reconstruction, with the pathology included within that time frame and
fee, is both cost efficient and labor efficient. Mohs surgery has been
especially designed for accuracy, tissue sparing, convenience, cost
efficiency, and labor efficiency.
Mohs surgeons are expert in the complete removal of complex skin
cancers, particularly on the central facial area. Mohs surgeons work
closely with our colleagues in oculoplastic surgery in the United States
to coordinate expert reconstruction of the resultant defects. In places
where Mohs surgery is less available, close communication between the
surgeon and pathologist, and tangential vertical margin processing may
offer a reasonable therapeutic option, although one that is more
inconvenient, costly and laborious for patients and physicians alike.
References
(1) J D Hsuan, R A Harrad, M J Potts, and C Collins. Small margin excision of periocular basal cell carcinoma: 5 year results. Br J Ophthalmol 2004; 88: 358-360.
(2) Cook J, Zitelli J. Mohs micrographic surgery: a cost analysis. J
Am Acad Dermatol. 1998;39:698-703.
The eLetter by Harun et al. on "Modification of classification of
ocular chemical injuries"[1] is to be commended in so far as it highlights
the problems with the current Roper-Hall classification system and the
difficulties it poses in evaluating outcome and efficacy of treatment
modalities in ocular surface burns. As a proposed modification however, it
is a retrograde step.
The eLetter by Harun et al. on "Modification of classification of
ocular chemical injuries"[1] is to be commended in so far as it highlights
the problems with the current Roper-Hall classification system and the
difficulties it poses in evaluating outcome and efficacy of treatment
modalities in ocular surface burns. As a proposed modification however, it
is a retrograde step.
The three major issues with the Roper-Hall [2]
classification were that it lumped all injuries with 50% or more of limbal
involvement into one category, did not take into account conjunctival
involvement in the actual classification and placed undue emphasis on the
degree of corneal haze.
The proposed modification by Harun S et al. goes a step backwards by
grouping all injuries with more than 33% limbal involvement (1/3) into one
category. The grading of a patient with all 12-clock hours of limbus
involvement would then be the same as one with just over 3 clock hours of
limbus involvement! The prognosis given to these two patients cannot be
the same, given that the Roper-Hall and the Dua, King and Joseph [3]
classifications are prognostic classifications. Furthermore, a patient
presenting with less than one third limbus involvement does not
necessarily come with less than one third conjunctival involvement, which
could be much more. The proposed modification does not allow for such
variances, which are frequent. The Dua, King and Joseph classification has
the flexibility to allow for such variables and also to progressively
document change both improvement and deterioration, over the acute phase
of the injury. The authors rightly point out that the degree of ischaemia
does not always correspond to degree of limbal involvement. Yet limbal
involvement without ischaemia, in the form of loss of stem cells, can have
an equally important impact on prognosis. That is precisely why the Dua,
King and Joseph classification considers limbal involvement (to encompass
ischaemia as well) rather than limbal ischaemia alone.
The point about conjunctival involvement is well made in the proposed
modification. This does not differ significantly from the Dua, King and
Joseph classification. The latter was the first to take this aspect of
burns into account in determining severity and prognosis. The authors
mention the importance of tarsal conjunctival involvement. This is a valid
though often an impractical consideration. Associated swelling,
induration, thickening, shrinkage and the like, of the lids make tarsal
conjunctival evaluation impractical if not impossible in some cases, in
the immediate post injury period. It was for this practical consideration
that the Dua, King and Joseph classification included only the extent of
bulbar conjunctival involvement in determining the grade. It is
interesting to note that the authors disregard limbal fluorescein staining
as an indicator of limbal damage (as proposed in the Dua, King and Joseph
classification) but propose fluorescein staining as an indicator of
conjunctival damage in evaluating extent of conjunctival damage. This
implies that fluorescein staining is appropriate to evaluate both
conjunctival epithelial damage and conjunctival ischaemia but not limbal
epithelial damage and limbal ischaemia. There is no rationale for this.
Corneal haze can be an indicator of the offending chemical rather
than the severity of the insult. It is not uncommon to find a clear and
transparent cornea, which is totally denuded of its epithelium,
immediately after a chemical injury. This can stay so for a few days
before becoming rapidly hazy or opaque, or remain clear and become re-
epithelised. Corneal endothelial damage leading to stromal edema and haze
can occur later in the course of an acute chemical injury. Conversely, a
hazy cornea with a resultant scar could do well following a corneal graft
procedure if the limbal involvement is minimal. The proposed modification
retains corneal haze as a grading parameter and includes a hazy cornea in
grade 3 only. There are many chemical injuries, which involve 3 to 6 clock
hours of the limbus (30 to 50%) with a clear cornea. These do not fall
well in any grade in the proposed new classification and highlight the
inherent problem in the Roper-Hall classification and its proposed
modification.
Most important of all, the proposed classification is purely
theoretical and has not been validated. The Dua, King and Joseph
classification is based on several years of clinical experience of
managing burns including over 67 patients. It is simple and easy to use
(clock hours of limbus involvement and percentage of conjunctival
involvement), flexible and allows for all combinations of different
extents of involvement of the two structures. It is validated as a
prognostic indicator and allows for accurate comparison of cases. The
proposed new classification/modification fails on all these counts.
References
(1) 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 2004http://bjo.bmjjournals.com/cgi/eletters/85/11/1379#219
(2) Roper-Hall MJ. Thermal and chemical burns. Trans Ophthalmol Soc UK
1965;85:631-53
(3) Dua HS, King AJ, Joseph A. New Classification of Ocular surface
burns. Br J Ophthalmol 2001; 85:1379-83
A recent paper by Kobayashi and
co-workers[1] on temporary amniotic membrane patching for acute
chemical burns highlights the difficulty in the consistent classification of
this type of injury.
Roper-Hall’s classification of
acute chemical injuries to the eye is based on the original classification of Ballen[4] and there is little difference between
them. However, in neither classification is the gra...
A recent paper by Kobayashi and
co-workers[1] on temporary amniotic membrane patching for acute
chemical burns highlights the difficulty in the consistent classification of
this type of injury.
Roper-Hall’s classification of
acute chemical injuries to the eye is based on the original classification of Ballen[4] and there is little difference between
them. However, in neither classification is the grade based on the most severe
sign. This immediately leads to the
problem of trying to classify an eye having, for example, corneal signs of one
grade and conjunctival signs of another. There is also difficulty in grading the conjunctival
and limbal injuries.
Dua et al.[2]
recognized the problem of assessing limbal stem cell damage and proposed a
quasi-analogue scale in order to incorporate inter-grade variations. They suggested using limbal
fluorescein staining as a marker of limbal stem cell damage. However, their
grading scheme is complex and departs significantly from that of
Roper-Hall. Although fluorescein
staining is a useful sign, it does not necessarily imply limbal stem cell
damage or failure and has not been shown to be a better index of limbal damage
than perilimbal ischaemia. Importantly, it is also becoming apparent,
that both the fornices and mucocutaneous junction of the conjunctiva are
important for conjunctival regeneration.[5,6] In fact, Roper Hall stressed the importance
of involvement of contiguous area of the conjunctiva, which may lead to symblepharon formation.[2]
Although there are limitations with
Roper-Hall’s classification, it is simple and remains popular. Rather than replace Roper-Hall and Ballen’s classification,[3] we suggest a
modification, which addresses some of the issues raised and makes the
classification more robust.
One of the questions that needs to be answered is whether to base the grade of injury
upon the most severe sign or on a combination of ocular surface signs. A combination of signs using 3 parameters
(cornea, limbus and conjunctiva) each with 3 levels requires 27 possible
combinations to avoid cross-over. To avoid this complexity and without
evidence to indicate a difference in prognosis, it would seem reasonable
therefore to base the grade of injury on the most severe sign.
Although limbal ischaemia does not
necessarily imply limbal stem cell failure, it remains to be shown that it is
less indicative than fluorescein limbal
staining of limbal damage. We propose therefore to continue to use limbal ischaemia in the grading of injury. With regard to conjunctival involvement, in
order to be able to include the total area of involvement, we suggest dividing
the conjunctival surface into bulbar and tarsal areas, as is natural. The bulbar and tarsal conjunctiva
comprise approximately two thirds and one third of the total
conjunctival surface respectively. Using conjunctival fluorescein staining as an indicator of
the extent of conjunctival damage, the area of involvement can be based on the
fraction of the third involved, limiting any division into not less than
sixths. That is, the tarsal surfaces
together comprise a third of conjunctiva (see Figure 1). This includes the issue that a vertical
distribution of conjunctival injury is as important as a horizontal
distribution.
Figure1 Estimation of Conjunctival injury
E.g, 1/6th
+1/6th = 1/3rd
Corneal involvement in terms of
prognosis remains an area of difficulty. Although it may be assumed that limbal and conjunctival damage implies a
worse prognosis than isolated corneal damage, this has yet to be shown. In addition, a severe chemical injury
involving the cornea but not the limbus, or vice
versa, would be expected to be an uncommon event. We therefore propose to retain the degree of
corneal damage (as proposed by Roper-Hall [3] and Ballen [4]) in grading of the injury (see Table 1).
Table 1 Modified Classification of
Ocullar Chemical Injuries
Grade
Cornea
Limbal
Ischaemia
Conjunctival involvement
Prognosis
I
Clear: epithelial damage only
None
None
Good
II
Clear: epithelial damage only
<1/3
<1/3
Good
III+
Hazy
cornea
OR
>1/3
OR
>1/3
Guarded
Thus grade I is identified by any
isolated corneal epithelial injury. Grade II includes limbal or conjunctival involvement, but involving less
than one third of the area involved. Grade III includes either a hazy cornea, defined as obscurity of the
iris or pupil details (as per Roper-Hall’s and Ballen’s
original descriptions), and/or greater than one third of limbal or conjunctival damage. With the advent of recent
surgical techniques such as amniotic membrane transplants and limbal allografts, the prognosis
of more severe ocular chemical injuries previously classified as Roper-Hall
grade IV have improved and no longer carry a uniformly poor prognosis.[2] Therefore we reason that these cases can be included in Grade III of our
proposed classification.
In conclusion, in the absence of
good evidence for re-classifying ocular surface injuries, it would seem
reasonable to keep to Roper-Hall / Ballen’s
classification and to move it forwards by addressing the weaknesses of that
system. We hope that the proposed
grading system improves the consistency with which chemical injuries are
reported in the literature, serves as a basis for controlled comparative
evaluation of modern treatment options and stimulates further work in this
area.
References
1. Kobayashi A, Shirao
Y, Yoshita T, et al.Temporory
amniotic membrane patching for acute chemical burns. Eye 2003; 17: 149-158
2. Dua
HS, King AJ, Joseph A. A new classification of ocular surface burns. BJO 2001;85:1379-1383
3. Roper-Hall MJ. Themal and
chemical burns. Trans Ophthalmol Soc UK
1965;85:631-53
4. Ballen
PH, Hemstead NY.Treatment
of chemical burns of the eye.Eye,Ear,
Nose and Throat Monthly 1964;43:57-61
5. Wirtschafter
JD., Ketcham JM, Weinstock
RJ, et al. Mucocutaneous junction as the major source
of replacement palpebral conjunctival epithelial cells. Inv Ophth Visual Science. 40(13):3138-46, 1999 Dec.
6. Wei ZG, Wu RL, Lavkar RM, et al. In vitro
growth and differentiation of rabbit bulbar, fornix and palpebral conjunctival
epithelia. Implications on conjunctival epithelial
transdifferentiation and stem cells. Inv Ophth
Visual Science 1993 Apr;34(5):1814-1828
7. Brodovsky
SC, McCarty CA, Snibson G, et al. Management of alkali burns: an 11
year retrospective review. Ophthalmology. 2000;107(10):1829-1835
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