Rapid Responses to:

EDITORIALS: Gerald Liew, Paul Mitchell, Jie Jin Wang, and Tien Yin Wong Fundoscopy: to dilate or not to dilate? BMJ 2006; 332: 3 [Full text]

Rapid Responses: Submit a response to this article

Rapid Responses published:

The risks of partial pupil dilation with other pharmacological agents

Peter D Cackett   (9 January 2006)

Diagnosis of acute angle closure glaucoma

Ranjan Rajendram   (10 January 2006)

Fundoscopy: to dilate or not to dilate? Precipitation of angle closure may not be a disservice…

Kanchan J Bhan, Andrew Bastawrous and Keith G Davey   (12 January 2006)

Other reasons for don-dilatation

Anthony E J Fitchett   (13 January 2006)

The Importance of Pupillary Dilatation in Ophthalmoscopy

Mohammad T Masoud   (13 January 2006)

First do no harm

Miss Roxane J. Hillier, Mr Graham Kyle, Consultant Ophthalmic Surgeon   (16 January 2006)

The real reason for not dilating?

Scott G Fraser   (17 January 2006)

Safety of pharmacological dilation of the pupil

Paul J Foster, Winnie P Nolan, Jennifer LY Yip   (18 January 2006)

Dilated fundoscopy is important and may be performed by optometrists

Ian E Murdoch, Michael D. Crossland, and Daniel P. Ehrlich   (25 January 2006)

The risk / benefit ratio of precipitating Angle Closure Glaucoma by systemic medications also needs to be considered.

Richard P Gale, Damian JM Tolan, Specialist Registrar Radiology, Leeds General Infirmary   (26 January 2006)

Risk of precipitating glaucoma with mydriatic eye drops in Singaporeans

Srinivasan Sanjay, Raghavan Lavanya, Kah-Guan Au Eong   (28 January 2006)

Eclipse sign to detect shallow anterior chamber

Deepa R Anijeet, Larry Benjamin   (5 February 2006)

Angle-closure in Asians is predominatly asymptomatic

Paul J Foster   (9 February 2006)

Authors' Response

Gerald Liew, Mitchell P, Wong TY, Wang JJ.   (9 February 2006)

The risks of partial pupil dilation with other pharmacological agents 9 January 2006
Peter D Cackett, Ophthalmology SpR Princess Alexandra Eye Pavilion, Chalmers Street, Edinburgh, EH3 9HA Send response to journal: Re: The risks of partial pupil dilation with other pharmacological agents	Liew et al. highlight the very small risks associated with precipitating an attack of angle closure glaucoma when dilating a pupil for the purposes of fundoscopy. We would agree with the authors that this is indeed because the use of mydriatic drops result in a pupil that is fully dilated rather than partially dilated and therefore less likely to cause pupil block. This can be illustrated further by the problems created by other pharmacological agents and their effects on the eye. The initiating event in acute angle closure glaucoma is incomplete mydriasis (pupil dilation) resulting in pupil block and the prevention of aqueous drainage through the trabecular meshwork. This partial mydriasis is normally caused by poor ambient lighting conditions but drugs with adrenergic and anticholinergic properties have also been identified as causative agents. These drugs include ipratropium1 and the tricyclic antidepressants2 and more recently the serotonin selective reuptake inhibitors (SSRIs) such as paroxetine (seroxat)3 and fluoxetine (prozac)4 have been implicated via their anticholinergic properties. The SSRIs have a lower incidence of anticholinergic effects than tricyclic antidepressants but some still remain.5 The British National Formulary advises caution with the use of these drugs in patients with a history of angle closure glaucoma. This is however misleading, as patients who have had an attack of angle closure glaucoma will hopefully have been treated with either iridotomies or trabeculectomies and therefore no longer be at risk. We would therefore recommend that all patients who are commenced on these drugs (ipratropium, tricyclics and SSRIs) be warned of the risk of ophthalmic symptoms (painful red eye, blurring of vision, headache, nausea and vomiting) especially those that are especially at risk (i.e. elderly, female, hypermetropic refractive error). This will hopefully result in reduced ocular morbidity in those patients that are unfortunate enough to develop this complication. 1 Singh J, O'Brien C, Wright M. Nebulized bronchodilator therapy causes acute angle closure glaucoma in predisposed individuals. Respir Med. 1993 Oct;87(7):559-61. 2 Ritch R, Krupin T, Henry C, Kurata F. Oral imipramine and acute angle closure glaucoma. Arch Ophthalmol. 1994 Jan;112(1):67-8. 3 Browning AC, Reck AC, Chisholm IH, Nischal KK. Acute angle closure glaucoma presenting in a young patient after administration of paroxetine. Eye. 2000 Jun;14 ( Pt 3A):406-8. 4 Ahmad S. Fluoxetine and glaucoma. DICP. 1991 Apr;25(4):436 5 Briley M, Moret C. Neurobiological mechanisms involved in antidepressant therapies. Clin Neuropharmacol. 1993 Oct;16(5):387-400 Competing interests: None declared
Diagnosis of acute angle closure glaucoma 10 January 2006
Ranjan Rajendram, Registrar Frimley Park Hospital, GU16 7UJ Send response to journal: Re: Diagnosis of acute angle closure glaucoma	Examination of the anterior chamber drainage angle by means of a contact lens (gonioscopy), and the observation of an predisposing, occludable angle would lead to a peripheral iridotomy being performed in order to prevent the occurence of acute angle closure glaucoma. As we do not routinely screen the population for occludable anterior chamber angles, presentation with acute angle closure glaucoma is difficult to prevent. A predisposed patient who has been asked to seek medical help if they experience any problems following dilated fundoscopy, would be likely to be seen promptly by an ophthalmologist and be able provide clear history of a precipitating factor, leading to a correct diagnosis and appropriate treatment. In contrast, a predisposed patient who has not had dilated fundoscopy may well attribute the symptoms of acute angle closure to a migraine and delay seeking medical help, particularly as a mid-dilated pupil is often associated with dim evening light. Competing interests: None declared
Fundoscopy: to dilate or not to dilate? Precipitation of angle closure may not be a disservice… 12 January 2006
Kanchan J Bhan, Specialist Registrar Huddersfield Royal Infirmary, Andrew Bastawrous and Keith G Davey Send response to journal: Re: Fundoscopy: to dilate or not to dilate? Precipitation of angle closure may not be a disservice…	We read with pleasure the editorial encouraging clinicians to dilate pupils for thorough fundoscopy. We would agree that the risk for precipitating angle closure glaucoma with Tropicamide 0.5% is very low. We would suggest that in the rare occurrence of precipitated angle closure, the event may not necessarily be a disservice to the patient for two reasons. Firstly, anyone whose angle may be provoked into closure by a mild mydriatic is at risk of spontaneous angle closure glaucoma. The fact that it has been precipitated in a health care setting, rather than occurring in the community is of some benefit. In such a scenario, one would expect a patient to be within easy access of specialist care. We do see patients who are at risk of angle closure but, for example, have a propensity to travel (either during the day or for extended durations as with the Armed Forces). Also, it is not unknown in this part of England for some communities to be stranded due to snow with no ambulance access for several days. Secondly, such an attack of angle closure would occur shortly after dilating drops are wearing off. Thus the symptoms of angle closure are likely to be attributed to the preceding use of mydriatic drops. As a result of this, the correct diagnosis should be made more quickly with treatment given promptly. Conversely, in cases of spontaneous angle closure it is well recognised that patients may not take notice of, or report, early symptoms. Clinicians too, may misinterpret symptoms or signs, leading to delay in diagnosis and a potentially poorer outcome. The fear of precipitating angle closure glaucoma should, hence, not impact upon the decision to dilate to perform accurate fundoscopy. Competing interests: None declared
Other reasons for don-dilatation 13 January 2006
Anthony E J Fitchett, General Practitioner Mornington Health Centre, 169 Eglinton Road, Dunedin, New Zealand. Send response to journal: Re: Other reasons for don-dilatation	Liew et al suggest that a reason for the low rate of dilatation of the pupil by general practitioners is the perceived risk of precipitating acute angle closure glaucoma. There may be others, more important. In the New Zealand context many of our patients drive to the consulting room for their appointment. Sending them away to drive with dilated pupils may incur higher risks than that of acute angle closure glaucoma. And is it necessary, at least in a so-called "First World" country, to dilate pupils to screen for diabetic retinopathy? Our diabetic patients are screened yearly, or more often if indicated, by retinal photography, which does not require dilatation and appears to be completely risk-free, apart from the hazards of travelling to the hospital clinic. Competing interests: I cannot remember ever dilating a pupil in my general practice setting to check for diabetic retinopathy
The Importance of Pupillary Dilatation in Ophthalmoscopy 13 January 2006
Mohammad T Masoud, Senior House Officer, Ophthalmology Stirling Royal Infirmary, Stirling. UK. FK8 2AU Send response to journal: Re: The Importance of Pupillary Dilatation in Ophthalmoscopy	The article by Gerald Liew et al was very appealing as it highlights the importance of dilated ophthalmoscopy in medicine. I agree with the authors that the risk of precipitating an attack of angle-closure glaucoma by dilating the pupils is minimal. A dilated fundus examination is indicated and is helpful in the diagnosis of conditions like diabetic retinopathy, hypertensive retinopathy, papilloedema, cataract and eye trauma. It is a skill that proves to be invaluable for physicians, general practitioners, surgeons, Accident and Emergency (A&E) staff and ophthalmologists alike. It is especially important for A&E doctors to be familiar with performance of ophthalmologic procedures for evaluation and treatment of a number of eye problems [1]. The ocular fundus allows a simple and non invasive visualisation of the terminal vascular system [2]. This is especially important in the examination of patients with diabetes mellitus and hypertension. Ophthalmoscopy can indicate in these conditions the vascular state in the other organs and permits direct diagnostic, prognostic and therapeutic choices. Dilated fundoscopy can improve the visualisation of fundus details, especially if the view is hazy due to a cataract or corneal opacities. It can also help pick up subtle abnormalities like early optic disc swelling. Various studies have indicated the benefits of dilated fundoscopy. Pollack et al found that the rate of detection through routine dilated fundus examination of clinically significant fundus lesions in asymptomatic patients at 2.73% [3]. Siegel et al conducted a study involving 500 adults, in which the fundus was examined with both natural and dilated pupils [4]. 38% of posterior pole anomalies requiring significant action by the doctor were missed during the natural pupil examination. Moreover 287 peripheral retinal anomalies were picked up in the dilated pupil examination. These results suggest that pupil dilatation should be strongly considered in all patients to increase the probability of detecting fundus abnormalities. I hope doctors from all specialities will be encouraged to perform more dilated ophthalmoscopy in the future. References: [1] Knoop K, Trott A. Ophthalmologic procedures in the emergency department--Part II: Routine evaluation procedures. Acad Emerg Med. 1995 Feb;2(2):144-50. [2] Barile P, Galand A.. How I explore...significance of ophthalmoscopy in patients with arterial hypertension. Rev Med Liege. 2004 Dec;59(12):734-8. [3] Pollack AL, Brodie SE. Diagnostic yield of the routine dilated fundus examination. Ophthalmology. 1998 Feb;105(2):382-6. [4] Siegel BS, Thompson AK, Yolton DP, Reinke AR, Yolton RL. A comparison of diagnostic outcomes with and without pupillary dilatation. J Am Optom Assoc. 1990 Jan;61(1):25-34. Competing interests: None declared
First do no harm 16 January 2006
Miss Roxane J. Hillier, SHO Ophthalmology Walton Hospital, Aintree University Hospitals NHS Trust, Rice Lane, Liverpool, L9 1AE, Mr Graham Kyle, Consultant Ophthalmic Surgeon Send response to journal: Re: First do no harm	EDITOR - No one could disagree that pharmacological dilation of the pupil is an essential component of the ophthalmic examination, and precipitation of acute glaucoma is rare1. However, we would like to exercise a word of caution, and remind readers not to underestimate the grave prognosis for vision that acute angle closure glaucoma carries unless early and aggressive treatment is instituted. This is particularly so in iatrogenic cases where it is likely to be bilateral. To illustrate our point, we describe a recent and tragic case. A 66 year old man attended clinic for the first time, where tropicamide 1% and phenylephrine 2.5% were instilled to both eyes to facilitate fundal examination. One hour after returning home, he developed a severe frontal headache, nausea and vomiting which were so debilitating that he retired to bed, hoping it would pass. Upon waking, his vision had deteriorated such that he was unable to locate the telephone, or navigate the fourteen flights of stairs down to the street. Thus, he remained a prisoner in his home for 48 hours before managing to call for help. At the hospital, he was found to have bilateral acute angle closure glaucoma. As a direct consequence of the delay in treatment his recovery has been slow, painful and incomplete. We do not suggest that wider use of mydriatic eye drops by non - ophthalmologists be discouraged. However, we would like to stress the following: (i) Patients must be warned in no uncertain terms of the importance of seeking immediate medical attention should they develop symptoms of angle closure glaucoma. (ii) Patients should also be advised to ensure reliable means to summon help in the hours following mydriasis, lest this devastating complication occurs. Reference 1. Liew G, Mitchell P, Wang J, Wong T. Fundoscopy:to dilate or not to dilate? BMJ 2006;332:3 Competing interests: None declared Editorial note The patient whose case is decsecribed has given his signed informed consent to publication.
The real reason for not dilating? 17 January 2006
Scott G Fraser, Consultant Ophthalmologist Sunderland Eye Infirmary Send response to journal: Re: The real reason for not dilating?	The editorial by Liew, Mitchell and Wong[1] discusses a topic important from both the patients and practitioner’s point of view. Those of us who see large numbers of ophthalmic patient each day are well aware that making an accurate diagnosis of any retinal condition is virtually impossible without dilating the pupil. As the authors point out, there is ample evidence that pupillary dilation very rarely causes angle closure. Patients who develop angle closure after pharmacological pupil dilation are highly likely to develop the condition anyway and are usually within a setting where more rapid diagnosis and referral can be made. The more puzzling aspect of this paper is why, when it is evident that all patients who need retinal examination should be dilated, is there a need for an editorial in a widely-read medical journal spelling this out? For me the answer lies in the psyche of doctors and perhaps other practitioners. We all worry about harming our patients but the harm seems so much worse when it appears to be as a direct result of our action. We mentally balance the outcome of the situation where we could miss an important diagnosis but which will present at some nebulous time in the future (hopefully far enough away for the patient not to feel something was missed) against the apparent immediacy of causing a problem by pupil dilation. The fear we have is that the juxtaposition of action with consequence means the patient is more likely to ‘blame’ us for the event. Patients with angle closure glaucoma are invariably treated by ophthalmologists and many of us have seen a number of patients who have been put into angle closure after pharmacological pupil dilation. One of the first things we tell these patients is that they were going to get angle closure glaucoma anyway and the dilation merely brought this event forward a little. Practitioners need to be aware that putting someone into angle closure is neither negligent nor blameworthy. Conversely missing proliferative diabetic retinopathy or a retinal detachment because of failure to dilate the pupil is. 1. 1. Liew G, Mitchell P, Wang J, Wong T. Fundoscopy:to dilate or not to dilate? BMJ 2006;332:3 Competing interests: None declared
Safety of pharmacological dilation of the pupil 18 January 2006
Paul J Foster, Consultant & Clinical Senior Lecturer Institute of Ophthalmology, London, Winnie P Nolan, Jennifer LY Yip Send response to journal: Re: Safety of pharmacological dilation of the pupil	Editor - Liew and colleagues rightly emphasized the benefits of pharmacological mydriasis in optimising detection of pathology by ophthalmoscopy.(1) However, the broader issues of safety for patients require several other points to be considered. In high-risk groups such as elderly women and especially Asians, who constitute increasingly sizeable minorities of the populations of English-speaking nations, angle-closure is asymptomatic (symptoms only occur in approximately 25%).(2) It is well- recognised that intraocular pressures of over 70 mm Hg may exist in white, quiet eyes, which inevitably have advanced, undiagnosed glaucomatous loss of vision. The proportion of Asians at risk of significant angle-closure is up to 13% in older people. In studies of glaucoma in Asia, we routinely gave such participants oral acetazolamide following dilation.(3) Liew mis- quotes our research, suggesting pharmacological dilation is “safe” in all Chinese people. This remains unproven. It is important to recognise that symptoms are not an infallible guide to the existence of clinically significant angle-closure. The simple solution for those who feel uneasy about dilation is to involve an eye-care professional (optometrist or ophthalmologist), seeking specific assurance that use of mydriatics is safe. In addition, this would enhance the detection of other glaucoma and other sight-threatening conditions. We feel strongly that diabetics who are undergoing regular examination under the care of general physicians should be instructed to continue regular eye examinations with an eye care specialist at yearly intervals to ensure that other important eye diseases are not overlooked. Liew and colleagues correctly emphasize the importance of instructing patients to seek medical attention if they experience symptoms of angle- closure following dilation of the pupil. Precipitating angle-closure with mydriatics that leads to prompt diagnosis and expeditious, definitive treatment may in fact be in the best interests of the individual. The problem remains unrecognised, asymptomatic angle-closure leading to severe loss of vision from glaucoma. References 1. Liew G, Mitchell P, Wang JJ, Wong TY. Fundoscopy: to dilate or not to dilate? BMJ 2006;332:3. 2. Foster PJ, Johnson GJ. Glaucoma in China: how big is the problem? Br J Ophthalmol 2001;85:1277-82. 3. Foster PJ, Oen FT, Machin DS, Ng TP, Devereux JG, Johnson GJ et al. The prevalence of glaucoma in Chinese residents of Singapore. A cross- sectional population survey in Tanjong Pagar district. Arch Ophthalmol 2000;118:1105-11. Competing interests: None declared
Dilated fundoscopy is important and may be performed by optometrists 25 January 2006
Ian E Murdoch, Consultant Ophthalmologist Moorfields Eye Hospital, City Road, London EC1V 2PD, Michael D. Crossland, and Daniel P. Ehrlich Send response to journal: Re: Dilated fundoscopy is important and may be performed by optometrists	We congratulate Liew and colleagues on emphasizing the importance of mydriasis for adequate fundoscopy and the minimal risk of inducing angle closure with dilation(1). In the UK, a detailed screening program for diabetic eye disease is now in place with excellent standards(2). The literature from this subject may, however, serve to illustrate what can be missed in the absence of dilation. Liew and colleagues slightly misquote Klein et al’s paper concerning decreased sensitivity(3). The authors of that paper found 54% agreement between finding retinopathy using direct ophthalmoscopy through an undilated pupil compared with findings using stereo fundus photography, whilst sensitivity for detection of any retinopathy was 70% of the value for stereo fundus photography. Even with this smaller figure the advantage of pupil dilation is profound. In the UK 1-6% of people with diabetes have retinopathy that requires therapy, of whom 6-9% would go blind each year(4). Dilated imaging has been shown to have a specificity of about 89%, and direct ophthalmoscopy a specificity of about 65% in expert hands(5). If 1000 patients were screened then 30 (3%) might reasonably be expected to have retinopathy requiring therapy. Using dilated imaging, three of these patients would be expected to be missed whilst 10 or 11 might be expected to be missed in the absence of dilation. Thus over three times as many treatable cases will be missed in the absence of dilation and one might be expected to go blind as a consequence of the lack of dilation. This risk compares to none or one person developing an attack of acute angle closure (that in itself need not be blinding if treated appropriately). The whole investigative process can be made even safer. Should GPs feel uneasy about dilation, due to the risk of angle closure or for any other reason, practitioners could ask a local optometrist to perform dilated funduscopy. Professional guidelines from the UK College of Optometrists require optometry practices to have slit lamp microscopes, tonometers and access to mydriatics(6), and optometrists have been shown to have high specificity and sensitivity in screening for diabetic retinopathy(7), glaucomatous disc parameters(8) and other retinal diseases. Community optometrists are ideally placed to work with general medical practitioners within the primary care sector to help ameliorate the growing burden on GP practices. References 1. Liew G, Mitchell P, Wang JJ, Wong TY. Fundoscopy: to dilate or not to dilate? BMJ 2006;332:3 (7 January). 2. Klein R, Klein B, Neider MW, Hubbard LD, Meuer SM, Brothers RJ. Diabetic retinopathy as detected using ophthalmoscopy, a nonmydriatic fundus camera and a standard fundus camera Ophthalmology 1985:92;485-491 3. The National Screening Programme for sight-threatening diabetic retinopathy. http://www.nscretinopathy.org.uk. Accessed 23 January 2006. 4. Bachmann MO, Nelson SJ. Impact of diabetic retinopathy screening on a British district population: case detection and blindness prevention in an evidence-based model. J Epidemiol Community Health 1998: 52;45-52. 5. Harding SP, Broadbent DM, Neoh C, White MC, Vora J. Sensitivity and specificity of photography and direct ophthalmoscopy in screening for sight threatening eye disease: the Liverpool diabetic eye study. BMJ 1995:311;1131-1135 6. The College of Optometrists. Code of ethics & guidelines for professional conduct. Members' handbook 2005. London: The College of Optometrists, 2005:1.01.1 - 2.40.1. 7. Prasad S, Kamath GG, Jones K, Clearkin LG, Philips RP. Effectiveness of optometrist screening for diabetic retinopathy using slit -lamp biomicroscopy. Eye 2001;15:595-601. 8. Theodossiades J, Murdoch I. What optic disc parameters are most accurately assessed using the direct ophthalmoscope? Eye 2001:15;283-287 Competing interests: MDC and DPE are Hospital based optometrists. MDC performs occasional sessions in community optometry practice.
The risk / benefit ratio of precipitating Angle Closure Glaucoma by systemic medications also needs to be considered. 26 January 2006
Richard P Gale, Specialist Registrar in Medical Ophthalmology Leeds General Infirmary, Damian JM Tolan, Specialist Registrar Radiology, Leeds General Infirmary Send response to journal: Re: The risk / benefit ratio of precipitating Angle Closure Glaucoma by systemic medications also needs to be considered.	We agree whole-heartedly with the comments made by Liew et al. Doctors using Tropicamide eye drops should be reassured that the risk of precipitating angle closure glaucoma is very small, but indeed the risk should never be overlooked and symptoms should be carefully described to patients. The risk of using the medication needs to be balanced with the risk of NOT using the medication. We would like to bring to the fore that it is not just mydriatic drops that can produce angle closure glaucoma. A number of systemic medications, such as Buscopan (used as an anti-spasmodic in gastro- intestinal radiological procedures), Chlorpromazine, (anti -psychotic) and Ipraptropium (brochondilator) also have a risk of causing angle closure glaucoma. On a population basis one must ask if the risk of using the medication is outweighed by the potential benefit? As with all medications used for individuals, when a drug is ‘routinely’ used the prescriber needs to make an informed decision about a risk / benefit ratio. So how far do we go about warning patients of side effects from new prescriptions? Should everyone be counselled about rare serious specific complications such as angle closure glaucoma, anaphylaxis or death? Where should you responsibly stop? Generally we should be realistic and practical in our advice and not myopic - in the spirit of the paper by Liew et al. Competing interests: None declared
Risk of precipitating glaucoma with mydriatic eye drops in Singaporeans 28 January 2006
Srinivasan Sanjay, medical officer in ophthalmology Department of Ophthalmology and Visual Sciences, Alexandra Hospital, 378 Alexandra Road, Singapore, Raghavan Lavanya, Kah-Guan Au Eong Send response to journal: Re: Risk of precipitating glaucoma with mydriatic eye drops in Singaporeans	We agree with Liew and colleagues that the risk of precipitating angle closure glaucoma with mydriatic eye drops is low.1 Singapore has a multiracial population comprising about 77% Chinese, 14% Malays, 8% Indians and 1% other races. In this population, the incidence of angle closure glaucoma is 12.2 per 100,000 per year in persons aged 30 years and older.2 Although Liew and colleagues cited that the risk of developing acute angle closure glaucoma in Chinese Singaporeans and Malay Singaporeans following pharmacological mydriasis is less than 1 in 1,000 and 1 in 2,400 respectively, these figures are not found in the cited articles.2,3 We would like to share our experience involving 1403 participants in a community eye screening programme for Singapore residents aged 55 years and older. All participants underwent non-contact 'air-puff' tonometry and a slit lamp examination by an ophthalmologist or optometrist before receiving a drop of 1% tropicamide in each eye for mydriasis prior to fundus photography. We had one case of unilateral angle closure glaucoma in a 68-year-old phakic Chinese woman following the pharmacological mydriasis in this cohort. References 1. Liew G, Mitchell P, Wang JJ, Wong TY. Fundoscopy: to dilate or not to dilate? BMJ 2006; 332:3. 2. Incidence of acute primary angle-closure glaucoma in Singapore. An island-wide survey. Arch Ophthalmol 1997; 115:1436-40. 3. Foster PJ, Oen FT, Machin D, Ng TP, Devereux JG, Johnson GJ, et al. The prevalence of glaucoma in Chinese residents of Singapore: a cross- sectional population survey of the Tanjong Pagar district. Arch Ophthalmol 2000; 118:1105-11. 4. Wong TY, Saw SM, Tan DTH. The Singapore Malay eye study. Am J Ophthalmol 2005; 139: S13. Srinivasan Sanjay1 medical officer in ophthalmology, sanjay_s@alexhosp.com.sg Raghavan Lavanya2 clinical research fellow in ophthalmology Kah-Guan Au Eong1,3-5 adjunct associate professor in ophthalmology 1Department of Ophthalmology and Visual Sciences, Alexandra Hospital, 378 Alexandra Road, Singapore 159964, Singapore 2Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore 168751 3Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074, Singapore 4Singapore Eye Research Institute, 11 Third Hospital Avenue, Singapore 168751, Singapore 5Department of Ophthalmology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore Competing interests: None declared
Eclipse sign to detect shallow anterior chamber 5 February 2006
Deepa R Anijeet, Senior House Officer Stoke Mandeville Hospital, Aylesbury, HP21 8AL, Larry Benjamin Send response to journal: Re: Eclipse sign to detect shallow anterior chamber	We read with interest the editorial by Liew et al 1. The need to dilate the pupil for assessment of diabetic retinopathy by the primary care physician is well documented . Even though the risk of precipitating acute angle closure glaucoma is small, it can cause significant morbidity to the patient and is potentially sight threatening. The eclipse sign using an oblique flashlight has been well described as a tool to detect shallow anterior chamber. A beam of light shone from the temporal aspect of the cornea towards the root of nose produces a semicircular shadow of the iris in the nasal area. The width of the semicircular shadow gives an indication of the depth of the anterior chamber. A shallow anterior chamber produces a broader shadow compared to an anterior chamber of normal depth as it is the eclipse of the light. Congdon et al 2 in a study of 562 people report a sensitivity of 80% and specificity of 69% for the oblique flash light test in detecting a shallow anterior chamber. Yu et al 3 in a study of 251 patients report a sensitivity of 96.67% and specificity of 74.53% with good inter and intraobserver agreement. However, Thomas et al 4 in a study of 96 patients report a sensitivity of 45.5% and specificity of 82.7% for the flash light test. Thus, while the oblique flash light test lacks the sensitivity or specificity of Van Herrick test or gonioscopy, it can be employed as a useful tool in detecting a shallow anterior chamber in the primary care physician’s office without a slit lamp. An appropriate referral to an ophthalmologist can help prevent an acute angle closure glaucoma precipitated by pupillary dilatation. References 1. Liew G, Mitchell P, Wong T Y. Fundoscopy: to dilate or not to dilate. BMJ 2006 ;332 : 7532-3 2. Congdon NG, Quigley HA, Hung PT, Wang TH, Ho TC. Screening techniques for angle- closure glaucoma in rural Taiwan. Acta Ophthalmol Scandinavia 1996; 74: 113-119 3. Yu Q, Li S, Ye T. Evaluation for grading standard of oblique flashlight test. Yen Ko Hsueh Pao (Eye Science) 1996; 12(2): 98-102 4. Thomas R, George T, Braganza A, Muliyil J. The flashlight test and van Herrick’s test are poor predicators for occludable angles. Aust NZ J Ophthalmol 1996; 24(3): 251-256 Competing interests: None declared
Angle-closure in Asians is predominatly asymptomatic 9 February 2006
Paul J Foster, Senior Lecturer/Consultant Ophthalmologist Institute of Ophthalmology, London Send response to journal: Re: Angle-closure in Asians is predominatly asymptomatic	Unfortunately, Dr Srinivasan and colleagues have again mis-quoted the results of our research, and mis-interpret the implications. The incidence of post-dilation angle-closure in Chinese Singaporeans is NOT < 1/1000, because all high-risk individuals were identified prior to pharmacological dilation, and were given a dose of oral acetazolamide to prevent pressure rises. Consequently, we have no idea what the natural course of events would have been, had they not been given prophylactic medication. This is why a figure for incident symptomatic angle-closure was not cited in our publication.(1) As stated in our previous comment, it is becoming increasingly clear that angle-closure in Asians is predominantly asymptomatic.(2) It is important to recognise that symptoms are NOT an infallible guide to the presence of clinically significant angle-closure. Unless Dr Srinivasan and colleagues measured the intraocular pressure of participants in their community screening programme at 2-4 hours post dilation, they will not be in a position to say how many people experienced a significant, but asymptomatic, rise in intraocular pressure. Perhaps they could clarify if this was done. If it was, then publication of the results in a peer-reviewed journal would be very useful to us all. 1. Foster PJ, Oen FT, Machin D, Ng TP, Devereux JG, Johnson GJ, et al. The prevalence of glaucoma in Chinese residents of Singapore: a cross- sectional population survey of the Tanjong Pagar district. Arch Ophthalmol 2000; 118:1105-11. 2. The epidemiology of primary angle-closure and associated glaucomatous optic neuropathy. Foster PJ. Semin Ophthalmol 2002;17:50-58. Competing interests: None declared
Authors' Response 9 February 2006
Gerald Liew, Research Fellow University of Sydney, NSW 2006, Mitchell P, Wong TY, Wang JJ. Send response to journal: Re: Authors' Response	Editor- We read with much interest the responses to our editorial “To Dilate or Not”.[1] We would like to reiterate again the main message of our editorial – that existing data show acute angle closure glaucoma from dilating eye drops is extremely rare, even in traditional high risk groups. This is not to say that acute angle closure after dilation could not occur - it will occur in an extremely small proportion of people, which the best available evidence puts at between 1 to 6 per 20,000 people in the general white population, and less than 1% in most high risk groups. Foster and colleagues believe we misquoted their research and claimed that pharmacological dilation is “safe” in all Chinese people. We did not assert that pharmacological dilation is completely safe in any group, and indeed quote from their work a risk of 1 in 1000 in Chinese, over three times the risk in Caucasians.[2] Sanjay and coworkers report from their clinical experience a similar rate of 1 in 1403 Singaporean Chinese but incorrectly cite the studies we refer to [2] and mention a study we did not refer to [3] which reported the incidence of acute primary angle closure glaucoma in the Singapore population, but not from pharmacological dilation. Nonetheless, we agree with Foster, Sanjay and colleagues that unrecognized, asymptomatic chronic angle closure glaucoma is potentially a major problem, but unfortunately there are few data on the relationship of this condition with pharmacological dilation. There may be reasons to avoid dilation, but we suggest that fear of precipitating acute angle closure glaucoma should not be one of them. As with most medical decisions, the benefits must be weighed against the risks, and benefits of early detection of diabetic retinopathy are clear, while the risk of acute angle closure glaucoma is very small. In fact, angle closure after dilation that results in earlier diagnosis and definitive management may be preferable to spontaneous angle closure and potentially delayed diagnosis, as lucidly pointed out by three of the correspondents (Rajendram, Bhan and Foster). Driving after pupil dilation could be a relative contraindication, although in our experience nearly all patients can still drive home safely after dilation particularly if sunglasses are worn to help with glare. If indicated, dilated eye examinations can and should be performed in general practice. 1. Liew G, Mitchell P, Wang JJ, Wong TY. Fundoscopy: to dilate or not to dilate? BMJ 2006;332:3. 2. Foster PJ, Oen FT, Machin D, Ng TP, Devereux JG, Johnson GJ, et al. The prevalence of glaucoma in Chinese residents of Singapore: a cross- sectional population survey of the Tanjong Pagar district. Arch Ophthalmol 2000;118:1105-11. 3. Seah SK, Foster PJ, Chew PT, Jap A, Oen F, Fam HB, Lim AS. Incidence of acute primary angle-closure glaucoma in Singapore. An island- wide survey. Arch Ophthalmol 1997; 115:1436-40. Competing interests: None declared