Measurement of blood–aqueous barrier breakdown

Ophthalmology Volume 108, Number 4, April 2001 Measurement of Blood–aqueous Barrier Breakdown Dear Editor: In their recent article Dowler et al found that in patients with diabetes mellitus, phacoemulsification was associated with less postoperative inflammation than extracapsular cataract surgery.1 The results of their excellent study confirm the clinical impression that small-incision surgery is less traumatic. However, we were surprised that in their prospective, randomized, paired-eye trial, they used a time-honored semiquantitative grading system for postoperative aqueous flare and aqueous cells that was described 41 years ago.2 In this scale, flare is subjectively assessed using a slit lamp as follows: 0 ⫽ complete absence, 1⫹ ⫽ faint flare (barely detectable), 2⫹ ⫽ moderate flare (iris and lens details clear), 3⫹ ⫽ marked flare (iris and lens details hazy).2 Since the development of the laser flare photometer, there exists a much more exact, observer-independent and reproducible method to quantify aqueous flare and, with somewhat less precision, aqueous cells.3 A number of studies have shown the usefulness of the laser flare photometer to assess blood–aqueous barrier breakdown in many ophthalmologic and systemic diseases, including patients with diabetic retinopathy4,5 and eyes after cataract surgery.6,7 The instrument also allows comparison of pre- and postoperative values.8 We believe that the results of this clinical trial might possibly even be more valuable with use of modern techniques to quantify postoperative blood–aqueous barrier breakdown. MICHAEL KU¨ CHLE, MD GOTTFRIED O.H. NAUMANN, MD Erlangen, Germany References 1. Dowler JGF, Hykin PG, Hamilton AMP. Phacoemulsification versus extracapsular cataract extraction in patients with diabetes. Ophthalmology 2000;107:457– 62. 2. Hogan MJ, Kimura SJ, Thygeson P. Signs and symptoms of uveitis. I. Anterior uveitis. Am J Ophth 1959;47:155–70. 3. Sawa M, Tsurimaki Y, Tsuru T, Shimizu H. New quantitative method to determine protein concentration and cell number in aqueous in vivo. Jpn J Ophthalmol 1988;32:132– 42. 4. Ku¨chle M, Scho¨nherr U, Nguyen NX, et al. Quantitative measurement of aqueous flare and aqueous “cells” in eyes with diabetic retinopathy. Ger J Ophthalmol 1992;1:164 –9. 5. Moriarty AP, Spalton DJ, Moriarty BJ, et al. Studies of the blood-aqueous barrier in diabetes mellitus. Am J Ophthalmol 1994;117:768 –71. 6. Shah SM, Spalton DJ. Changes in anterior chamber flare and cells following cataract surgery. Br J Ophthalmol 1994;78: 91– 4. 7. Dick HB, Schwenn O, Krummenauer F, Krist R, Pfeiffer N. Inflammation after sclerocorneal versus clear cornea tunnel phacoemulsification. Ophthalmology 2000;107:241–7. 8. Schumacher S, Nguyen NX, Ku¨chle M, Naumann GOH. Quantification of aqueous flare after phacoemulsification with intraocular lens implantation in eyes with pseudoexfoliation syndrome. Arch Ophthalmol 1999;117:733–5.

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Author’s reply Dear Editor: We thank Drs. Ku¨chle and Naumann for their interest in our article1 and agree with them that the use of a laser flare photometer in our study would have provided valuable data regarding the extent of blood–aqueous barrier breakdown after cataract surgery. At the start of the trial, our decision not to use this device was based on the fact that its capacity to quantify cellular anterior chamber activity is, as they acknowledge, less accurate than its capacity to detect flare;2 and in our institution, therapeutic intervention is usually titrated against cells rather than flare. Nonetheless, their suggestion is most helpful, and we would certainly consider the use of the laser flare photometer in future trials. JONATHAN DOWLER, MD, FRCOPHTH PHILIP HYKIN, FRCOPHTH A.M. PETER HAMILTON, FRCOPHTH London, England References 1. Dowler JGF, Hykin PG, Hamilton AMP. Phacoemulsification versus extracaspular cataract extraction in patients with diabetes. Ophthalmology 2000;107:457– 62. 2. Sawa M, Tsurimaku Y, Tsuru T, Shimizu H. New quantitative method to determine protein concentration and cell number in aqueous in vivo. Jpn J Ophthalmol 1988;32:132– 42.

Micro-Reflex Test vs. the Kleenex Test Dear Editor: As a pediatric ophthalmologist, I have reviewed the article by Dr. Camara et al on the Micro-Reflux Test. Indeed, this may well be a useful test for nasal lacrimal duct obstruction in adults, but in children it is hard to get young babies to the slit lamp to do massage to see if there is reflux from the sac. We have studied an even simpler test for nasal lacrimal duct obstruction in children, which is called the “Kleenex Test.” In a normal child, if you fold a Kleenex in half and press it against the inner canthus there are no tears on the tissue. In a child with partial or complete nasal lacrimal duct obstruction, there is an excessive amount of tears in the tear film, which is absorbed by the Kleenex, and this amount can be measured in square millimeters of area by measuring the size of the wetting. We have found in studies in our office, yet unpublished, that the square millimeters of tears noted on the Kleenex test correlate linearly with the amount of dye present in the eye after a dye retention test. We therefore no longer do a dye retention test in the office and simply blot a Kleenex into the tear film to look at the amount of excess tears caused by the lacrimal obstruction. Of course, excessive tear production rather than blockage can give an abnormal Kleenex test, but this is an extremely rare occurrence in children. HOWARD L. FREEDMAN, MD, FAAP Redmond, Washington Author’s reply Dear Editor: We thank Dr. Freedman, Micro-Reflux Test (MRT), for his