Recent eLetters
Displaying 301-310 letters out of 403 published
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The Public like 8am-5pm Weekday Clinics
Submit responseDear Editor
We were interested to read of the positive feedback that Zaldi et al. received from patients attending Saturday morning Ophthalmic clinics at Hillingdon Hospital.[1] The authors raise some interesting questions that we are delighted to be able to address. We feel it is important to highlight the differences between this and our two-centre study.[2] Whilst both groups aimed to address the same issue, the cohort of individuals questioned, the delivery of the questionnaire and the nature of the questions that were asked differed in the two studies.
Zaldi et al. questioned a group of patients attending a Saturday morning clinic in London. This was a select group and excluded all those individuals who either failed to attend or attended during Mon-Fri. In contrast, we invited all patients attending out-patients over a 2 week period to participate in an effort to minimise bias from selecting just one day of the week. Secondly, we conducted our survey at two centres, one in the North (Leeds) and one in the South West (Bristol) in an attempt to more accurately reflect public opinion across the UK. Zaldi et al. point out that in London there is a unique weekday congestion charge that might bias the results from their study in favour of attendance at a Saturday morning clinic.
In the London study the questionnaire was verbally administered by the examining ophthalmologist which might have introduced a ‘desire to please’ from the patients and therefore bias the results. We felt that by allowing individuals to remain anonymous we might obtain more accurate responses to our questionnaire.
Finally, and perhaps of most importance, is the fact that the questions differed in the two studies. The London group directly asked their patients to state whether they had a preference for either a Saturday morning or a 9am-5pm weekday clinic. This produced the figure that 50% did not mind when they attended and 41% preferred a Saturday morning. By contrast in our study we asked individuals to state whether their appointment time was ‘convenient’ or ‘inconvenient’. We found that 89% individuals found their weekday appointment time convenient. A further 7% preferred a different time within the existing 8am-5pm weekday framework. Only 4% stated that a weekday appointment between 8am-5pm was inconvenient. We then asked patients to comment on whether they would find alternative clinic times convenient or inconvenient. We did not ask patients to rank these alternatives in order of preference. From this question we found that 52% would find a Saturday morning appointment convenient. Although the questions are slightly different in the 2 studies, our figure of 52% is in broad agreement with the London study which showed 50% individuals did not mind whether they attended on a weekday or a Saturday morning.
We conclude by stressing that only 4% individuals found their 8am-5pm weekday appointment time inconvenient and 48% would find a Saturday morning appointment inconvenient. Given that the Government supports ‘patient choice’, we feel that these figures justify an expansion of the existing framework rather than the introduction of regular ‘out of hours’ clinics.
References
(1) Zaidi FH, Lee N. Public opinion favours out-of-hours clinics: interviews challenge multi-centre questionnaire [electronic response to Churchill et al. Public opinion on weekend and evening outpatient clinics] bjophthalmol.com 2003 http://bjo.bmjjournals.com/cgi/eletters/87/3/257#133
(2) A J Churchill, C Gibbon, S Anand, and M McKibbin. Public opinion on weekend and evening outpatient clinics. Br J Ophthalmol 2003;87:257-258.
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I did not find ketamine either safe or effective.
Submit responseDear Editor
I read the article by Pun et al.[1] with interest. My experience with ketamine is (thankfully) limited to operating in Bosnia after the war. Out of the six patients one vomited on the field. Difficulty is encountered in re-ops due to lack of muscle paralysis. Ketamine also has well known after effects. In my opinion it is neither safe nor effective. Learning and using safe anesthesia techniques would be the best in any country.
Reference
(1) M S Pun, J Thakur, G Poudyal, R Gurung, S Rana, G Tabin, W V Good, and S Ruit. Ketamine anaesthesia for paediatric ophthalmology surgery. Br J Ophthalmol 2003;87:535-537.
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Partial flaps during LASIK: Reply to Dr Perera
Submit responseDear Editor
We thank Dr Perera [1] for his interest in our article.[2] We do agree with him that the results of partial flaps without ablation and good flaps with ablation are not comparable, which in fact was not the aim of the study.
The primary aim of the study was to evaluate the changes in the posterior corneal elevation after the partial flaps. We, in this article, attempted to evaluate the changes in posterior corneal elevation after partial flaps in cases that were planned to have LASIK surgery. Based on our results we concluded that the inadvertent occurrence of partial flap during LASIK procedure does not contribute to an additional increase in posterior corneal elevation. Further, we only suggested, but did not conclude that evaluation of the posterior corneal surface topographic changes after partial flaps without ablation may help us to understand the contribution of the flap (even if it is partial) to the corneal elasticity. This is more so as raising a flap alone in the absence of photo ablation for the purpose of studying the mechanism of posterior corneal elevation may be not be practical and ethical.
References
(1) Perera S. Partial flaps during LASIK [electronic response to Sharma et al. Posterior corneal topographic changes after partial flap during laser in situ keratomileusis] bjophthalmol.com 2003 http://bjo.bmjjournals.com/cgi/eletters/87/2/160#121
(2) N Sharma, A Rani, R Balasubramanya, R B Vajpayee, and R M PandeyPosterior corneal topographic changes after partial flap during laser in situ keratomileusis. Br J Ophthalmol 2003;87:160-162.
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Re: Intravitreal triamcinolone acetonide for exudative age-related macular degeneration
Submit responseDear Editor
We read the article on intravitreal triamcinolone injections for exudative age-related macular degeneration with interest.[1] The paper stated that visual acuity increased significantly (p <_0.001 from="from" _0.16="_0.16" _0.11="_0.11" to="to" a="a" mean="mean" maximum="maximum" of="of" _0.23="_0.23" _0.17.="_0.17." the="the" authors="authors" therefore="therefore" picked="picked" best="best" one="one" up="up" _10="_10" postoperative="postoperative" visual="visual" acuity="acuity" measurements="measurements" and="and" compared="compared" it="it" with="with" single="single" preoperative="preoperative" measurement.="measurement." this="this" is="is" misleading="misleading" reader="reader" regarding="regarding" true="true" effectiveness="effectiveness" treatment.="treatment." p="p"> The Macular Photocoagulation Study Group found that the differences in between two repeated tests was one line or more in 13% of cases and the differences were greatest in patients with visual acuity of 20/100 or worse.[2] By taking up to 10 postoperative measurements, Jonas et al. greatly increased the chances of a positive result. The difference between mean pre-injection 0.16 (20/125 or 6/36) and best mean postoperative 0.23 (20/87 or 6/26) was less than one line on the Snellen chart.
Table 1 gave the mean visual acuity pre-injection and at various time intervals post-injection. At 1 and 2 months, the p values were 0.04. It was unclear whether the p values were one or two tailed but both were described as not significant (NS) in table 1. Multiple significance testing at each of a number of time points is generally not recommended - if it is done, some kind of adjustment to the p values is needed.[3,4] Looking at the results presented table 1, the readers might conclude that triamcinolone had a transient and doubtful beneficial effect on the visual acuity.
The authors go on to further analyse the results into improvements of 3 and 6 or more lines. The vision was tested on a Snellen chart which has irregular steps. Three or 6 lines do not therefore represent a constant change in visual angle (as in a logMAR chart) and therefore the analysis was confusing.
Variations in intraocular pressure of 5 or 6 mmHg occur diurnally in normal individuals as well as glaucomatous patients.[5-7] Whilst there is little doubt that triamcinolone may affect the intraocular pressure, the comparison of the baseline with the highest (p <_0.001 was="was" misleading="misleading" as="as" the="the" comparison="comparison" of="of" highest="highest" with="with" that="that" at="at" _7="_7" months="months" p0.001.="p0.001." more="more" interest="interest" might="might" be="be" number="number" patients="patients" who="who" had="had" very="very" high="high" levels="levels" range="range" extended="extended" to="to" _64="_64" mmhg="mmhg" and="and" whether="whether" these="these" intraocular="intraocular" pressures="pressures" responded="responded" treatment.="treatment." p="p"> The authors’ experience in using triamcinolone is well recognised. We congratulate them on an otherwise excellent piece of work.
References
(1) Jonas JB, Kreissig I, Degenring R. Intraocular pressure after intravitreal injection of triamcinolone acetonide. Br J Ophthalmol 2003;87(1):24-7.
(2) Blackhurst DW, Maguire MG. Reproducibility of refraction and visual acuity measurement under a standard protocol. The Macular Photocoagulation Study Group. Retina 1989;9(3):163-9.
(3) Altman DG. Practical Statistics for Medical Research. London: Chapman and Hall, 1991.
(4) Matthews R. The numbers don't add up. New Scientist 2003;177(2385):28.
(5) Pointer JS. The diurnal variation of intraocular pressure in non- glaucomatous subjects: relevance in a clinical context. Ophthalmic Physiol Opt 1997;17(6):456-65.
(6) De_Vivero C, O_Brien C, Lanigan L, Hitchings R. Diurnal intraocular pressure variation in low-tension glaucoma. Eye 1994;8(Pt5):521-3.
(7) Smith J. Diurnal intraocular pressure. Correlation to automated perimetry. Ophthalmology 1985;92(7):858-61.
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Public opinion favours out-of-hours clinics: interviews challenge multi-centre questionnaire
Submit responseDear Editor
We read with keen interest the recent article by Churchill et al. that reports a multicentre questionnaire studying out-of-hours clinics.[1] The authors are to be commended for their initiative in performing the first appraisal of patient’s attitudes to government proposals to introduce out- of-hours clinics and operating sessions.[1]
However, it is still left unclear to us as to the accuracy of a key concluding remark of the authors, which we believe is contentious, potentially misleading, and should benefit from clarification by the authors to prevent any confusion. Specifically, we are concerned with the statement that the study found that only 4% of patients will ‘opt for’ out -of-hours clinics. This is a statement of considerable import, which we find extremely surprising given our personal experience of patients attending Saturday morning clinics and based upon a series of interviews we have conducted. When earlier reporting their results the authors also use the figure of 4% to quantify the number of patients reported to have stated that an appointment between 8am and 5pm, Monday to Friday, was inconvenient. Since we are so surprised by the sense of the statement that only 4% of patients will ‘opt for’ out-of-hours clinics, we question whether the authors might not have interpreted this figure of 4% by transposing it from the 4% that found a routine weekday appointment inconvenient, in which case their statement becomes very misleading. Clarification is needed both for the regular readership and beyond, for this is the first study of its kind in a key area of clinical debate, and is thus influential. Even if substantiated, this figure of 4% that are stated to ‘opt for’ out-of-hours clinics might mislead, as the study’s own breakdown of results shows that 52% of patients found Saturday morning clinics ‘convenient’. This breakdown also states that 58% found Saturday morning clinics ‘inconvenient’. But a study we conducted disputes these findings, and suggests instead a spectrum of opinions which by and large resonate with the government’s proposals in this regard.
In a series of interviews conducted by us, 102 consecutive patients who actually attended out-of-hours Saturday morning eye clinics at the Hillingdon Hospital were specifically asked by the examining ophthalmologist whether they preferred a Saturday morning clinic appointment, a routine 9-to-5 weekday clinic, or if they did not mind one way or the other. The results are strikingly different to that suggested by Churchill et al. A slight majority, or 51 patients (50%) simply did not mind whether they were seen on a Saturday morning or in a routine weekday 9-to-5 clinic. The second largest group of 42 patients (41%) said that they actually preferred a Saturday morning clinic, while the smallest group were 9 patients (9%) who said that they preferred a weekday 9-to-5 clinic appointment. Total number of female patients was 65, and male patients 37. Of those preferring Saturday morning clinics 41 % were female and 59% were male. Mean age of patients who preferred Saturday morning clinics was 62, while of those who preferred a weekday appointment it was 70. Reasons for preferring Saturday morning clinics included the following: it was easier for working people and students, which accounts for the younger mean age of patients preferring Saturday morning clinics; reduced traffic; car parking was easy; the hospital was relatively quiet on a Saturday morning making access easy, which was especially important for older people; finally, recent introduction of the weekday ‘congestion charge’ in central London meant that a Saturday morning clinic best suited older patients as friends or relatives saved on the cost of the journey by avoiding travel through central London to pick up the patient and transport them to the hospital – however, this is a factor at present unique to London. Amongst those who were not concerned whether they had a 9-to-5 weekday appointment or one on a Saturday morning, the overwhelming majority, or 86%, were retired. Reasons given for preferring a 9-to-5 weekday clinic appointment were, with six young mothers, children under the age of 12 at home, as the children were at school or nursery during weekdays but not weekends; hospital transport was felt to be easier to obtain on a weekday; surprising reasons were found in two patients who said that they preferred a 9-to-5 weekday appointment so as to have an extra day off work by going to the doctors, while one patient felt a Saturday morning hospital appointment was an infringement into ‘leisure’ time.
While this interview study has fewer patients, there is no missing data for all patients responded at interview - unlike the multicentre study in which only 54% of the despatched questionnaires were used for the analysis. Importantly, these interviews might also be more realistic in that they take into account the experiences of people who have actually attended an out-of-hours clinic. Alternately, it is possible that the markedly different results have arisen as we interviewed patients attending only Saturday morning clinics, while the concluding statement of the authors concerned out-of-hours clinics in general. However, even if this is the case, interviews suggest that the attitude amongst the public to Saturday morning clinics is positive.
Reference
(1) Churchill AJ, Gibbon C, Anand S, McKibbin M. Public opinion on weekend and evening outpatient clinics. Br J Ophthalmol 2003;87:257-8.
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Authors' Reply
Submit responseDear Editor
The authors wish to thank Gandorfer and colleagues for their interest in our paper [1] and for the kind comments and encouragement with regard to our work. Certainly, these correspondents are compiling evidence concerning the effect of indocyanine green (ICG) on the retina in both their published and unpublished studies.[2,3]
In our report, we restricted our comments regarding retinal damage and dye usage to the specimens wherein an epiretinal membrane (ERM) was present.[1] Evidence of retinal damage was observed in four of these five specimens, mostly in the form of neural and glial elements adherent to the retinal side of the inner limiting membrane (ILM). The apparent lack of such elements in some ERM specimens may reflect partial separation of the ILM due to traction from the membrane prior to surgery. [4] Nevertheless, in one of our specimens a substantial fragment of neuroretina was also present.[1] We have, indeed, long considered such fragments as potential confounding factors in immunohistochemical studies of surgically-excised ERMs.[5,6] Since they are present in ERMs removed without the use of any dye at all, we cannot blame their presence on these surgical aids. Perhaps these fragments are avulsed as a result of enhanced adhesion between the ERM and retina via glial anchorage sites running through dehiscences in the ILM.[5] It is clear that our investigation does not exclude an effect of ICG on the retina [2,3] and we wholeheartedly agree with Gandorfer and coworkers that agents such as trypan blue warrant further evaluation as aids to ERM and ILM peeling.
References
(1) Li K, Wong D, Hiscott P, Stanga P, Groenewald C, McGalliard J. Trypan blue staining of internal limiting membrane and epiretinal membrane during vitrectomy: visual results and histopathological findings. Br J Ophthalmol 2003;87:216-9.
(2) Gandorfer A, Haritoglou C, Gass CA, Ulbig MW, Kampik A. Indocyanine green-assisted peeling of the internal limiting membrane may cause retinal damage. Am J Ophthalmol 2001;132:431-3.
(3) Gandorfer A, Haritoglou C, Gandorfer A, Kampik A. Retinal damage from indocyanine green in experimental macular surgery. Invest Ophthalmol Vis Sci 2003;44:316-23.
(4) Michels RG. A clinical and histopathologic study of epiretinal membranes affecting the macula and removed by vitreous surgery. Trans Am Ophthalmol Soc 1982;80:580-656.
(5) Hiscott PS, Grierson I, Trombetta C, Rahi AHS, Marshall J, McLeod D. Retinal and epiretinal glia an immunohistochemical study. Br J Ophthalmol 1984;68:698 707.
(6) Morino I, Hiscott P, McKechnie N, Grierson, I. Variation in epiretinal membrane components with clinical duration of the proliferative tissue. Br J Ophthalmol 1990;74:393 9.
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The use of surgical facemasks during cataract surgery
Submit responseDear Editor
We read with interest the paper by Alwitry showing that the use of surgical facemasks significantly reduced the contamination of agar plates placed in the sterile field during cataract surgery.[1] Previous work has shown that, compared to remaining silent, talking significantly increases the dispersal of bacteria to agar plates placed 30 cm in front of and below the face, particularly if required to speak loudly.[2,3] The use of a surgical facemask prevents contamination of agar plates placed in front of the talking operator.[4] Similar reductions in contamination may be found when agar plates are placed below the operator’s mouth, although this may be partially offset in bearded male operators compared to female operators and clean shaven males as dermabrasion by the mask may increase shedding of skin and bacteria.[5,6]
During cataract extraction using topical anaesthesia it is not uncommon for the operator to continue talking with the patient giving reassurance and directing eye movements. It might be expected that in these circumstances there would be an increase in bacterial dispersal compared to akinetic anaesthetic techniques where such communication is seldom required. Consequently, it would be interesting to know from Alwitry’s study whether there was any difference in anaesthetic techniques between the masked and unmasked groups as this may significantly alter bacterial colony counts.
References
(1) Alwitry A, Jackson E, Chen H, Holden R. The use of surgical facemasks during cataract surgery: is it necessary? Br J Ophthalmol 2002;86:975-977.
(2) O'Kelly S, Marsh D. Face masks and spinal anaesthesia. British Journal of Anaesthesia 1993;53:239
(3) Schiff FS. The shouting surgeon as a possible source of endophthalmitis. Ophthalmic Surg 1990;21:438-40
(4) Phillips B, Fergusson S, Armstrong P et al. Surgical face masks are effective in reducing bacterial contamination caused by dispersal from the upper airway. Br J Anaesth 1992;53:407-8.
(5) McLure HA, Talboys CA, Yentis SM et al. Surgical face masks and downward dispersal of bacteria. Anaesthesia 1998;53:624-626.
(6) McLure HA, Mannam M, Talboys CA et al. The effect of facial hair and sex on the dispersal of bacteria below a masked subject. Anaesthesia 2000;55:173-6.
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Silicone oil in diabetic vitrectomy
Submit responseDear Editor
Castellarin and colleagues [1] recount their recent experience of infusing silicone oil in a small series of patients with advanced diabetic eye disease, either during primary vitrectomy (12 eyes) or after earlier surgery had failed (11 eyes). They compare their results with previous reports and conclude that silicone oil remains a useful adjunct in diabetic vitrectomy. However, their conclusions and historical comparisons are open to question.
Silicone oil was first used in primary diabetic vitrectomy in an era (1979-84) before the introduction of endolaser and the Landers' double concave lens for phakic fluid: air exchange.[2-4] Dealing with large or multiple posteriorly-located breaks (whether pre-existing or iatrogenic) was problematic, and direct fluid:silicone oil exchange (by virtue of the optical advantages of oil over air in the phakic eye) provided a surgical escape route, obviating the need for lensectomy. Furthermore, the clarity of the media immediately postoperatively facilitated the slit-lamp delivery of focal laser in order to seal retinal breaks that had been closed by the internal tamponade, and in addition the application of scatter laser to re-attached, untreated, ischaemic retina that had undergone deturgescence, in part through the 'waterproofing' effect of silicone oil.[3,4] All being well, the silicone oil could then be removed shortly thereafter, and some eyes that would undoubtedly have been lost were saved by the intervention of silicone oil in this way. Often, however, there were considerable associated problems, not least the rapid development of reparative epiretinal fibrosis whereby the retina re-detached under tangential traction and/or from re-opening of retinal breaks.[2-6] Sometimes huge areas of retinal disintegration eventually developed.[5,7] The fibroglial epiretinal proliferation appeared (both clinically and pathologically) to be particularly induced by clotted blood trapped between the silicone oil and the retinal surface or, ironically, by fibrin released as a result of the extensive scatter laser that was often needed to prevent highly vascularised membranes from re-proliferating behind the silicone oil.[4,5,8,9]
It was hoped that the so-called 'compartmentalisation' of the eye by silicone oil (to which the retro-silicone oil neovascularisation was attributed) might in turn result in prevention or reversal of rubeosis iridis through its putative barrier effect against anterior diffusion of angiogenic substances derived from the ischaemic retina.[3-8] Paradoxically, eyes with successful retinal reattachment (albeit with unabated ischaemia) often underwent rapid development or progression of iris neovascularisation,[3,8] while those with failed surgery from postoperative rhegmatogenous recurrence of retinal detachment (and therefore eyes with an exaggerated angiogenic drive) had evidence of protection from rubeotic phthisis, at least in the short term.[3] Perhaps naively it was postulated that rhegmatogenous confinement of the re-detachment by intravitreal silicone oil (and the consequent 100% oil filling of the shrinking vitreous cavity) might allow an effective obstruction to anterior molecular diffusion to be established in these failed cases.[3] Others had planned from the outset to employ silicone oil in their surgical protocol, not least for those diabetic eyes wherein earlier vitrectomy had been unsuccessful as a consequence of retinal re-detachment [4,10,11] or recurrent vitreous cavity haemorrhages.[4] However, whether used during primary diabetic vitrectomy or secondarily, whether unpremeditated or planned, and whether infused by direct fluid:oil exchange or sequential fluid:air and air:oil exchanges, the possibility of silicone oil limiting rubeosis and maintaining macular attachment despite peripheral retinal re-detachment was always welcome, even if surgical 'success' (that is, retinal attachment through 360 degrees) had strictly been denied.[2-4,8,12]
Nowadays, posterior retinal breaks and retinectomies can generally be managed successfully by employing wide-angle viewing systems, heavy liquids, endolaser, and long-acting gases. However, silicone oil continues to be infused during diabetic vitrectomy despite the attendant posterior segment and anterior segment complications that have only been partially mitigated by the improved quality of the silicone oil. The important question that thus arises is: what is the appropriate use of silicone oil in the diabetic eye in the modern era? Where retinal breaks might be closed just as readily using gas tamponade, or where rubeosis iridis might be reversed or prevented by retinal reattachment and/or a sufficiency of scatter laser photocoagulation, the use of silicone oil might be described fairly as 'gratuitous'. Exceptions might include anticipated posturing difficulties [3] or the need for early visual rehabilitation in one-eyed patients.[4] However, recent reports documenting the use of silicone oil in diabetic vitrectomy have failed to provide clear criteria or explanations regarding case selection.[1,12,13] Only 7 of the 23 eyes in Castellarin and colleagues' series, for example, had retinal breaks (2 pre-existing, 4 iatrogenic and 1 retinectomy), so the need for prolonged internal break tamponade was presumably not an issue in the majority of their eyes. More information is needed on the rationale for silicone oil infusion (not just the overall indications for surgery) in the remaining eyes in order to enable the potential benefits of this surgical adjunct to be assessed at this time. Furthemore, surgical success can really only be judged after a minimum of six months from the last vitreoretinal procedure,[3,4,8,10-12] and that judgement should preferably include consideration of whether the silicone oil has been removed and the status of the fellow eye.[14] The fact that 10 of the 23 eyes in Castellarins series were followed for only one or two months was thus a further serious limitation of their study.[1]
Infusion of silicone oil can be a most beguiling option during the closed microsurgical management of the stricken diabetic eye but, as mentioned, complications are prone to accumulate with time. Distinguishing the gratuitous from the virtuous use of silicone oil can be problematic, and equally it may be difficult to define the line between a surgeon's infusing silicone oil in anticipation of eventual surgical failure and such infusion representing his/her unstated admission that surgical failure has occurred already. All these issues need to born in mind when making historical comparisons between case series and in defining the place in history for silicone oil in diabetic vitrectomy.
References
(1) Castellarin A, Grigorian R, Bhagat N, et al. Vitrectomy with silicone oil infusion in severe diabetic retinopathy. Br J Ophthalmol 2003; 87: 318-21.
(2) Lean JS, Leaver PK, Cooling RJ, McLeod D. Management of complex retinal detachments by vitrectomy and fluid/silicone exchange. Trans Ophthalmol Soc UK 1982;102: 203-5.
(3) McLeod D. Silicone-oil injection during closed microsurgery for diabetic traction retinal detachment. Graefe's Arch Clin Exp Ophthalmol 1986; 224:55-9.
(4) Lucke KH, Foerster MH, Laqua H. Long-term results of vitrectomy and silicone oil in 500 cases of complicated retinal detachment. Am J Ophthalmol 1987; 104: 624-33.
(5) Barry PJ, Hiscott PS, Grierson I, et al. Reparative epiretinal fibrosis after diabetic vitrectomy. Trans Ophthal Soc UK 1985; 104: 285- 96.
(6) Charles S. Vitreous surgery, 2nd edition Baltimore: Williams and Wilkins, 1987. Pp 115-31.
(7) Wilson-Holt N, Gregor Z. Spontaneous relieving retinotomies in diabetic silicone filled eyes. Eye 1992; 6: 461-4.
(8) Yeo JH, Glaser BM, Michels RG. Silicone oil in the treatment of complicated retinal detachments. Ophthalmology 1987; 94: 1109-113.
(9) McLeod D, James CR. Viscodelamination at the vitreoretinal juncture in severe diabetic eye disease. Br J Ophthalmol 1988; 72: 413-9.
(10) Rinkoff JS, de Juan E, McCuen BW II. Silicone oil for retinal detachment with advanced proliferative vitreoretinopathy following failed vitrectomy for proliferative diabetic retinopathy. Am J Ophthalmol 1986; 101: 181-6.
(11) Brourman ND, Blumenkranz MS, Cox MS, Trese MT. Silicone oil for the treatment of severe proliferative diabetic retinopathy. Ophthalmology 1989; 96 : 759-64.
(12) Azen SP, Scott IU, Flynn HW Jnr, et al. Silicone oil in the repair of complex retinal detachments. A prospective observational multicenter study. Ophthalmology 1998;105: 1587-97.
(13) Scott IU, Flynn HW Jnr, Lai M-Y, Chang S, Azen SP. First operation anatomic success and other predictors of postoperative vision after complex retinal detachment repair with vitrectomy and silicone oil tamponade. Am J Ophthalmol 2000; 130: 745-50.
(14) McLeod D. Microsurgical management of neovascularisation secondary to posterior segment ischaemia. Eye 1991; 5: 252-9.
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Staining of the ILM in macular surgery
Submit responseDear Editor
We read with interest the article by Dr Li and colleagues about trypan blue staining of the vitreomacular interface during vitrectomy [1]
We congratulate the authors on their work. In particular, we appreciate their critical approach of testing trypan blue for staining of the internal limiting membrane (ILM) and epiretinal membrane (ERM) as well as their comments on potential untowards effects of indocyanine green (ICG) in macular surgery. We would like to comment on two remarks concerning the ultrastructural findings on the retinal side of the ILM following ILM- removal with and without the use of ICG.
We agree with Dr Li and collegues that fragments of glial cells are commonly found in ILM-specimens. Ultrastructurally, they appear as tiny fragments of Müller cell membranes adherent to and enclosed within the undulations of the retinal side of the ILM. These glial structures had been described in detail by Eckhardt and collegues, and are in accordance with previous work of our group, in an investigation of the ultrastructure of the vitreomacular interface of 93 specimens in 91 consecutive patients with macular holes, epiretinal membranes, diffuse diabetic macular edema, and vitreomacular traction syndrome without the use of indocyanine green or other dyes (unpublished data).[2] We also agree with the authors, that the surgical technique and the underlying disease may influence the amount of glial structures adherent to the retinal side of the ILM, as these structures are predominantly found within undulations and folds of the ILM.[3,4] However, we would like to emphasize the effect of ICG in this context. Firstly, there are obvious differences between ILM specimens removed with and without the use of ICG not only in terms of quantity of glial structures but in terms of quality. A continuous layer of cell membranes, undetermined cellular debris, and entire footplates of Müller cells were commonly observed following ICG-assisted peeling of the ILM, whereas such structures had never been found in the series of 93 unstained specimens described above.[5] Secondly, all stained and unstained specimens having been investigated by electron microscopy were removed by one experienced surgeon (A.K.). Beside the use of ICG, there was no change of the surgical technique. Moreover, retinal elements as described above were not found before the introduction of the dye at our institution in September 2000, nor after having stopped ICG-staining in April 2001. Thirdly, in an experimental setting in human donor eyes published recently, retinal structures adherent to the undulating side of the ILM as described above could be found following the application of ICG to the macula only.5 No attempt of peeling or any other mechanical approach to the vitreomacular interface was made in these eyes. However, the ILM was detached from the macula. Retinal elements were adherent to the retinal side of the ILM showing an identical morphology like those obtained during vitrectomy with ICG-assisted ILM-removal.[6] Therefore, in our experience, there is increasing evidence that at least some commonly used preparations of ICG may affect the ultrastructure of the inner retina, and are primarily responsible for obvious differences in the ultrastructure of the surgically removed ILM. ILM-removal by itself results in removal of tiny fragments of Müller cell membranes. Their morphological and functional implications to the macula remain unknown. Finally, we would like to encourage the authors to follow-on their promising approach of staining the ILM and ERM with trypan blue. In our institution, single specimens which had been stained and peeled using trypan blue revealed no evidence of retinal damage (submitted data).
References
(1) K Li, D Wong, P Hiscott, P Stanga, C Groenewald, and J McGalliard. Trypan blue staining of internal limiting membrane and epiretinal membrane during vitrectomy: visual results and histopathological findings. Br J Ophthalmol 2003;87:216-219.
(2) Eckardt C, Eckardt U, Groos S, Luciano L, Reale E. [Removal of the internal limiting membrane in macular holes. Clinical and morphological findings]. Ophthalmologe 1997;94:545-51.
(3) Haritoglou C, Gandorfer A, Gass CA, Kampik A. Ultrastructure of epiretinal tissue removed during indocyanine green assisted peeling in macular pucker surgery [ARVO Abstract No 3516]. Invest Ophthalmol Vis Sci 2002.
(4) Haritoglou C, Gandorfer A, Gass CA, Schaumberger M, Ulbig M, Kampik A. Indocyanine green-assisted peeling of the internal limiting membrane in macular hole surgery affects visual outcome: a clinicopathologic correlation. Am J Ophthalmol 2002;134:836-41.
(5) Gandorfer A, Haritoglou C, Gass CA, Ulbig MW, Kampik A. Indocyanine green-assisted peeling of the internal limiting membrane may cause retinal damage. Am J Ophthalmol 2001;132:431-3.
(6) Gandorfer A, Haritoglou C, Gandorfer A, Kampik A. Retinal damage from indocyanine green in experimental macular surgery. Invest Ophthalmol Vis Sci 2003;44:316-23.
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We are not in the States. Beware BSCS
Submit responseDear Editor
I read with interest the editorial by Dr DF Chang on SBCS and find myself in agreement with many of his points raised. A note of caution however. Several years ago when I had converted to topical clear cornea phako I started to perform SBCS on patients I felt required this and were suitable. As I saw the benefits for both the patients and the staff I decided to extend this to the majority of my patients. I was quickly stopped in my tracks when we discovered that SBCS is classified and reimbursed to our NHS hospital as a single procedure.
This is even if the patients is listed as two separate procedures. Our hospital could obviously not afford to "reduce" my operating list from 10 cataracts to 5 and at the same time use 10 sets of equipment and 10 IOLs etc every list. Therefore in the NHS one would have to very careful before embarking on SBCS until the purchasers or PCGT or whatever they will become in Foundation Status agree that it is more than a single procedure. I know DF Chang is relating his practice in the USA but after all the BJO is mainly about the practice of Ophthalmology this side of the Pond!
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