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Home , Acanthamoeba keratitis

LETTERS TO THE EDITOR

Sir, in the treatment of epithelial basement membrane I note that in their paper describing the treatment of dystrophy. Arch Ophthalmol 1983;101:392-5. recurrent erosions of the , l Bernauer et al. 2. Buxton IN, Carstad WHo Superficial epithelial keratect­ dismiss mechanical debridement of the cornea as a omy. Cornea 1987;6:292-7. method of treatment of recalcitrant cases. However, 3. Hykin PH, Foss AE, Pavesio C, Dart JKG. The natural they may have proved its efficacy. history and management of recurrent corneal erosion: a prospective randomised trial. Eye 1994;8:35-40. Before they can claim that excimer laser treatment has any added benefit, they really need to do a controlled trial to compare debridement followed by Sir, ' laser, with debridement alone. Karen Goodall and colleagues1 described three case histories from patients, the aetiology of the G. Kyle, FRCS FRCOphth infection being but the medical picture being reminiscent of adenovirus keratitis. Walton Hospital We have reported similar observations? Adenovirus Rice Lane keratitis was the preliminary clinical diagnosis in a Liverpool L9 1AE contact wearer who presented at casualty with a UK painful , when symptoms had been apparent for some 10 days. There was punctate epithelial Reference keratitis reminiscent of early adenovirus infection. 1. Bernauer W, pe Cock R, Dart JKG. Phototherapeutic After a further 8 days, various sub-epithelial ill keratectomy recurrent corneal erosions refractory to infiltrates had developed. At this stage, Acantha­ other forms of treatment. Eye 1996;10:561-4. moeba was isolated from a corneal scrape. Sir, Early recognition in a soft wearer of Mr Kyle has raised an important issue. Mechanical unilateral conjunctival inflammation, with photopho­ debridement of the cornea is not dismissed in our bia and excessive lacrymation, in the presence of a paper. It was referred to as superficial keratectomy 'typical' epitheliopathy or pseudo-dendrite, with sub­ and two references were given.1,2 This technique epithelial opacities in some patients, provides a requires removal of all the epithelium to the limbus. strong index of suspicion of Acanthamoeba keratitis. We agree that a randomised control trial is required The clinical diagnosis is reinforced if there is to test the different techniques for the management excessive pain and corneal perineuritis is observed of refractory recurrent corneal erosion syndrome. using the slit lamp. The observation of Goodall et at. Because the natural history of recurrent erosion is in cases of adenoviral corneal infection, that focal benign, with relatively few patients requiring invasive sub-epithelial opacities are present later beneath treatment, 3 we believe this would have to be a epithelial lesions, and that this feature is unusual multicentre trial to recruit enough patients. Until this before 6-9 days, is a useful parameter for differential is done we could not comment on the relative diagnosis. A further potentially confusing situation is efficacy of superficial keratectomy versus laser afforded by the so-called tight fit or over-wear treatment for the management of this condition. syndrome, which can present in the contact lens wearer with conjunctival inflammation, punctate John K. G. Dart, MA, DM, FRCS epithelial keratitis and sub-epithelial infiltrates? The latter triad of signs can be readily confused Moorfields Eye Hospital clinically with both adenovirus infection of the City Road cornea and early Acanthamoeba keratitis. London EC1V 2PD Investigations of contact lens wearing patients UK with a clinical diagnosis of adenovirus kerato­ should, if possible, include isolation of the virus from the swabs or conjunctival scrapings, References . 1. Buxton IN, Fox ML. Superficial epithelial keratectomy usmg susceptible cell cultures. This is time-consum-

Eye (1997) 11, 570-574 © 1997 Royal College of Ophthalmologists LETTERS TO THE EDITOR 571 ing, however, and may take up to 3 weeks before a References result is available. 4 Enzyme immunoassay for 1. Goodall K, Brahma A, Ridgway A. Acanthamoeba adenovirus type 8 can also be used for confirmation,S keratitis: masquerading as adenovirus keratitis. Eye as can immune dot blots. 6,7 Such methods can 1996;10:643--4. provide a result within 3-7 days. It is necessary to 2. Ledee DR, Hay J, Byers TJ, Seal DV, Kirkness CM. Acanthamoeba griffini: molecular characterisation of a be aware, however, of the limitations of such new corneal pathogen. Invest Ophthalmol Vis Sci techniques. We favour the use of transmission 1996;37:544-50. electron microscopy for virus detection, but recog­ 3. Kenyon KR, John T. Complications of soft contact nise that this facility may not be available in all eye lenses. In: Ruben M, Guillon M, editors. Contact lens practice, vol 6. London: Chapman & Hall, 1994:1070. institutes. Such non-culture methods are useful since 4. Bryden AS, Bertrand J. Diagnosis of adenovirus they can permit fairly early exclusion of a viral conjunctivitis by enzyme immunoassay. Br J Biomed aetiology, and allow for investigation of a differ­ Sci 1996;53:182--4. ential diagnosis of Acanthamoeba keratitis. Confir­ 5. Wood SR, Sharp IR, De Jong VC, Verweij-Uiterwaal mation of this infection may be provided in many MW. Development and preliminary evaluation of an enzyme immunosorbent assay for the detection of instances within 1 hour of receipt of a corneal adenovirus type 8. J Med ViroI1994;44:348-52. sample, by simply examining the tissue using phase 6. Morris DJ, Klapper PE, Killough R, Bailey AS, Nelson contrast microscopy. Culture on non-nutrient agar J, Tullo AB. Prospective study of adenovirus antigen prepared in enriched amoebal saline should follow. detection in eye swabs by radioimmune dot-blot. Eye 1995;9:629-32. There is no reliable method for unequivocal 7. Klapper PE, Cleator GM. Adenovirus cross-infection: diagnosis of 'tight fit' lens syndrome, but symptoms a continuing problem. J Hosp Inf 1995;30 and signs appear to abate rapidly when the contact (Suppl):262-7. lenses are removed from the eye. 8. Hay J, Kirkness CM, Seal DV, Wright P. Drug Acanthamoeba Adenovirus kerato-conjunctivitis treatment is pal­ resistance and keratitis: the quest for alternative chemotherapy. Eye liative and it is conventional to use analgesics and 1994;8:555-63. NSAIDs. Use of antibiotics, for example chloram­ 9. Ficker L, Seal DV, Warhurst D, Wright P. Acantha­ phenicol, is not generally required. moeba keratitis: resistance to medical therapy. Eye Goodall et al. reported that the combination of 1990;4:835-8. (as Brolene) and did not 10. Seal DV, Hay J, Kirkness CM, Morrell A, Booth A, Tullo A, et at. Successful medical therapy of Acantha­ 3 provide a successful outcome in one of their moeba keratitis with topical and propa­ patients with Acanthamoeba keratitis. This treat­ midine. Eye 1996;10:413-21. ment regimen has now been superseded. Cysts from most strains tested are resistant to Acanthamoeba Sir, neomycin, at least s Some strains are in vitro. We very much enjoyed the mathematical model resistant to propamidine. 9 If a patient has proto­ proposed by Aylward and Lyons for achieving a zoologically confirmedAcanthamoeba keratitis, it is single intraocular gas bubble during retinal reattach­ our contention that the treatment provided should ment surgery. 1 As the authors point out, creation of a comprise the combination of chlorhexidine (0.02 %) single bubble greatly facilitates the subsequent and Brolene; this regimen has been shown to be an fundus view allowing accurate and localised retino­ effective treatment, and is particularly useful if pexy. However, the risk of subretinal gas with commenced at an early stage in amoebal infection multiple small bubbles is likely to be influenced, in of the cornea. lO addition, by other factors. The greatest risk of subretinal gas relates to its use Myra A. Arnott with pneumatic retinopexy in patients with vitreous Department of Medical Microbiology detachment and horseshoe tears. This occurs early, University of Edinburgh Medical School and is not apparently related to subsequent gas Teviot Place expansion? Access to the subretinal space is only Edinburgh EH8 9AG possible if gas is behind the posterior hyaloid UK membrane (PHM) and care should be taken to ensure that the gas injection is carried out anterior to John Hay the PHM (Fig. 1). If the PHM is inadvertently David V. Seal breached then the gas injection may force it Tennent Institute of anteriorly, opening the break leading to subretinal Western Infirmary gas bubbles (Fig. 2) ('gas bubble squeezes itself , 38 Church Street through ...like a baby's head during delivery 2). In Glasgow G 11 6NT addition, new breaks can be produced by separating UK the PHM beyond its arrested insertion? Fortunately,