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LETTER TO EDITOR |
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Year : 2007 | Volume
: 55
| Issue : 5 | Page : 404-405 |
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Authors' reply
Arun K Jain, Reema Bansal, A Rajwanshi
Advanced Eye Centre, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012, UT, India
Correspondence Address: Arun K Jain Advanced Eye Centre, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012, UT India
Source of Support: None, Conflict of Interest: None | Check |
DOI: 10.4103/0301-4738.33844
How to cite this article: Jain AK, Bansal R, Rajwanshi A. Authors' reply. Indian J Ophthalmol 2007;55:404-5 |
Dear Editor,
We thank Chatterjee for showing their interest in our article. [1]
The impression smear was taken after cleaning the eye of any discharge, slough or necrotic material. In the histopathologic study of 73 cases, [2] it was observed that "characteristically the fungi were found throughout the entire thickness of the cornea."
In a recent histopathologic and microbiologic study of 167 corneal buttons fungus observed in all layers or in the anterior two-thirds in 112 [88%] cases contradicts previous observation of absence of fungus on the corneal surface. [3] All these cases had received antifungals before undergoing therapeutic keratoplasty. In the present study none of the cases were exposed to antifungal medications preceding the visit to our institution [see exclusion criteria]. [1]
In this study we did not correlate the impression smear positivity with size of the ulcer. Out of 50 cases only 14 [28%] were less than 2 mm in size with impression KOH smear positive in six [42.8%]. The rate of positivity of KOH smears for fungi has been reported to be 44.6% for corneal ulcer size >2 mm in diameter and 13.06% for those < 2 mm in size. [4]
In the present study impression material was retransferred to the glass slide. [1] Yield with cellulose acetate filter membranes can be increased by transferring impressions from the cellulose acetate filter to a gelatin-coated slide. [5] The latter is a more convenient technique than the use of unmounted Biopore membranes which have proved difficult to handle. [6]
In the setting of diverse healthcare systems and different prevalence of bacterial and fungal pathogens causing corneal ulceration, managing corneal ulcer becomes a major challenge. The key in the management of fungal keratitis is early diagnosis and institution of antifungal therapy. Prophylactic topical antibiotic and antifungal ointment following traumatic corneal abrasion has been found to be effective in preventing development of bacterial or fungal corneal ulcers. [7]
Culture and direct microscopic detection of causative organisms are the widely used microbiological investigations. However, at the level of community care of corneal ulcers there is disregard for recommended procedures prior to therapy even in the developed countries. This pattern of practice is not recommended or accepted as of now for suspected fungal keratitis. Some evidence of demonstrable fungi either on KOH smear, Gram or Giemsa stain, confocal microscopy or culture is required to start the antifugal therapy.
We are not advocating skipping the recommended laboratory microbiology workup. But there is concern about the treatment of corneal ulcers managed primarily in the community setting. Most of these patients have rural background. Specificity and accuracy to classify fungal keratitis by artificial neural network [ANN] approach have been proved to be 100% and 90.7% respectively. [8] Though in the hands of cornea specialists, sensitivity and specificity of clinical diagnosis of fungal keratitis is 94.1% and 94.58% respectively, [9] the same cannot be expected in a community setting where patients with corneal ulcers are being treated by comprehensive ophthalmologists, general care physicians and doctors from other specialties. [9] Does that justify starting antifungal therapy on empirical basis?
Most of the peripheral health centers have no slit-lamp available. But a simple laboratory microscope is available in each primary health center for examination of blood smears for malaria. So a simple impression KOH smear of suspected fungal corneal ulcer, at the time of first visit of patient to primary health center may make a difference in the diagnosis, treatment, timely referral and desirable outcome of the corneal ulcer management.
We think this technique is not superfluous in the diagnosis of fungal keratitis and we are not advocating the incorporation of the technique as an additional tool in the existing protocol. But in community practice setting, this technique does hold promise. All these methodologies of impression cytology of the ocular surface have been invaluable as research tools but have not yet become routine diagnostic tools in most clinics. [6] We still advocate complete microbiological workup of a case of infective keratitis. Repeated mechanical debridement of fungal corneal ulcer should be done to decrease the fungal load and enhance antifungal drug penetration.
References | | |
1. | Jain AK, Bansal R, Felcida V, Rajwanshi A. Evaluation of impression smear in the diagnosis of fungal keratitis. Indian J Ophthalmol 2007;55:33-6. [ PUBMED] [ FULLTEXT] |
2. | Naumann G, Green WR, Zimmerman LE. A histoplathologic study of 73 cases. Am J Ophthalmol 1967;64:668-82. [ PUBMED] |
3. | VemugantiGK, Garg P, Gopinathan U, Naduvilath TJ, John RK, Buddi R, et al . Evaluation of agent and host factors in progression of mycotic keratitis: A histologic and microbiologic study of 167 corneal buttons. Ophthalmology 2002;109:1538-46. |
4. | Bharathi MJ, Ramakrishnan R, Meenakshi R, Mittal S, Shivakumar C, Srinivasan M. Microbiological diagnosis of infective keratitis: Comparative evaluation of direct microscopy and culture results. Br J Ophthalmol 2006;90:1271-6. [ PUBMED] [ FULLTEXT] |
5. | Dart J. Impression cytology of the ocular surface - Research tool or routine clinical investigation? Br J Ophthalmol 1997;81:930. [ PUBMED] [ FULLTEXT] |
6. | Baudouin C, Haouat N, Brignole F, Bayle J, Gastoud P. Immunopathological findings in conjunctival cells using immunofluorescence staining of impression cytology specimens. Br J Ophthalmol 1992;76:545-9. |
7. | Maung N, Thant CC, Srinivasan M, Upadhyay MP, Priyadarsini B, Mahalaxmi R, et al . Corneal ulceration in South East Asia. II: A strategy for the prevention of fungal keratitis at the village level in Burma. Br J Ophthalmol 2006;90:968-70. |
8. | Saini JS, Jain AK, Kumar S, Vikal S, Pankaj S, Singh S. Neural network approach to classify infective keratitis. Curr Eye Res 2003;27:111-6. [ PUBMED] |
9. | Bharathi MJ, Ramakrishnan R, Vasu S, Meenakshi R, Palaniappan R. Epidemiological characteristics and laboratory diagnosis of fungal keratitis. A three-year study. Indian J Ophthalmol 2003;51:315-21. |
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