LETTERS

each test. I EIA worked best in Herptran medium and AGG tested positive for one sample in Chlamydia trans­port medium. We believe that Herptran could be appro­priate for other immunologic tests since Herptran solu­bilizes the herpes simplex antigen, which may improve the sensitivity.

In our article, we stated that Dunkel et al reported that Herpchek was 90% sensitive when correlated with cell culture-positive specimens. We should have stated that it was 100% sensitive as Mr. Crosby indicates. However, the major problems with Herpchek is not its sensitivity, but its limited application for the diagnosis of herpetic keratitis in terms of cost. Most cases of herpetic keratitis can be accurately diagnosed by the ophthalmologist based on slit­lamp examination. Dunkel et al state the " ... typical cases of ocular HSV infection are recognized readily by slit-lamp examination ... " and that " ... 30 patients with clinically diagnosed ocular HSV infection were all HSV antigen positive by the Herpchek assay ... " In our study of37 specimens, we determined that " ... the clin-ical diagnosis of HSV infection after a thorough ophthalmic examination was as sensitive as any of the immunologic tests . . ." In our opinion, both studies failed to show that Herpchek offered any advantage over the clinical examination in the diagnosis of most cases of herpetic keratitis.

While Herpchek may have a role in the diagnosis of atypical cases of herpetic keratitis, one must determine if it is cost-effective. Herpchek is a very expensive test. The minimum overhead cost to run one sample is approxi­mately $50, not including photometric instrumentation. In comparison, other tests in our study including cell cul­ture isolation were all under $20. In these days of ever­increasing medical costs, the responsible clinician must carefully weigh whether the confirmation of a clinical di­agnosis of HSV and/or the likelihood of a positive result in the atypical situation is worth the expense of this test.

REGIS P. KOWALSKI, MS Y. J. GORDON, MD

Pittsburgh, Pennsylvania

Delayed Reabsorption of Subretinal Fluid after Pneumatic Retinopexy

Dear Editor:

We read with great interest the article entitled, "Delayed Subretinal fluid Absorption after Pneumatic Retinopexy" (Ophthalmology 1989; 96:1691-700). Those cases with macular involvement were of particular interest. We also have noted the complication of delayed subretinal fluid absorption involving the macula in three cases in an initial series of 73 pneumatic retinopexy procedures.

After reading the article by Chan and Wessels, one is left with the impression that delayed reabsorption of sub­retinal fluid involving the macula portends a poor prog­nosis for long-term visual acuity. Our experience suggests

that this may not be the case, even with longer periods of macular detachment than reported by the authors. The authors did not specify the duration of preoperative mac­ular detachment in the two cases that presented with a detached macula. This may explain the poor visual out­come in these cases.

In two of our cases, one of which presented with an attached macula, residual subretinal fluid was present at the macula for 12 and IS months. The visual acuity during the period of macular detachment was 20/40 and 20/50, respectively, and improved in both eyes to 20/30 after resolution of the submacular fluid . In the other case, the visual acuity before retinal detachment was 20/200 due to macular degeneration, and did not decrease.

Delayed reabsorption of subretinal fluid occurred in only 3 of 10 I cases in our expanded series, a significantly lower frequency than reported by Chan and Wessels (II %). This difference may be due in part to case selection, although the indications for pneumatic retinopexy used by these authors appear not to differ significantly from those used in our series.

We believe that delayed reabsorption of subretinal fluid involving the macula after pneumatic retinopexy may oc­cur with significantly less frequency than suggested by Chan and Wessels and may in some cases be associated with an excellent visual prognosis.

Authors' reply

Dear Editor:

JOHN S. AMBLER, FRACO SANFORD M. MEYERS, MD HERNANDO ZEGARRA, MD

Cleveland, Ohio

We appreciate the comments by Ambler and associates regarding our article. We find that pneumatic retinopexy is a very useful technique for selected cases of retinal de­tachment, and believe that it has made a valuable addition to the armamentarium of the retinal surgeon.

In one of the two cases that did not specify the duration of retinal detachment, the original detachment was ex­tramacular, persisting for 3 weeks before surgery. Post­operative loculated submacular fluid developed and per­sisted for 6 months. In the other case, macular detachment was present for I week before surgery. The subsequent loculated submacular fluid persisted for over 6 months.

Although sound visual outcome may be achieved ul­timately in some cases after absorption of the loculated sub macular fluid, bothersome visual symptoms often are present while the submacular fluid persists. As stated in our article, the long duration of the loculated fluid is a hallmark of this phenomenon, and most of our patients with loculated submacular fluid experienced fluctuating visual acuity, metamorphopsia, minification, diplopia, etc., at a distressing level for many months. The symptoms experienced by the affected eyes may often interfere with the function of their fellow eyes for a prolonged period.

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