Avoid common mistakes on your manuscript.
Dear Editor,
As anterior chamber flare measurements have been reported to increase with age, Dr. Yoon raised the possibility that age may have acted as a confounder in our study. Particularly so, as the number of patients in our randomized study were relatively small.
Therefore, we entered age as covariate in the model. The effect of age on flare was not significant. According to the model estimates, it appeared that flare increased by 0.8 % per year of age (P = 0.23; 95% CI: -0.6% to +2.3%). Also, the conclusions concerning the treatment effect (dexamethasone versus placebo) hardly changed when entering age as covariate in the model, as patients with dexamethasone had 1-week flare measurements 49.9 % lower than patients given placebo (P = 0.030; 95% CI: 72.9% to 7.2% lower). These results are essentially the same as in our paper, where age was not included as a covariate. Thus, age was not a confounder in our study, and the changes in flare measurements we reported are likely to be caused by the use of dexamethasone.
Dr Yoon’s second and important question concerned the relation between the anterior chamber flare measurements (ACFM) we used and the blood–retina barrier breakdown we assumed to be studying, as a factor in the development of PVR.
In uveitis patients, a temporal relation was shown between clinical signs of posterior segment inflammatory activity and ACFM [2]. In rabbits [3], photocoagulation of the retina was shown to result in raised ACFM.
Are these raised anterior chamber flare measurements reflecting a spillover of posterior segment proteins, or are they mediated by inflammatory cytokines diffusing from the posterior segment forward to the ciliary body and iris, as suggested by raised ACFM in rabbits after intravitreous injections of interleukin 1 and 6 and prostaglandin E2 [3], a type of inverted Irvine-Gass mechanism?
To better answer Dr Yoon’s excellent question, we would need studies in patients correlating ACFM with fluorophotometer readings as used in patients to measure blood–retina barrier breakdown [4]. An interpretational difficulty here would be that this method measures fluorescein leakage, a non-functional molecule, which may not neccasarily be as physiological a measure as anterior chamber flare readings, which correlate with albumen and IgG leakage[1].
References
Chiou AG, Florakis GJ, Herbort CP (1998) Correlation between anterior chamber IgG/albumin concentrations and laser flare photometry in eyes with endogenous uveitis. Ophthalmologica 212(4):275–277
Herbort CP, Guex-Crosier Y, de Ancos E, Pittet N (1997) Use of laser flare photometry to assess and monitor inflammation in uveitis. Ophthalmology 104(1):64–71
Inoue M, Tsukahara Y, Shirabe H, Yamamoto M (2001) Disruption of the blood-aqueous barrier following retinal laser photocoagulation and cryopexy in pigmented rabbits. Ophthalmic Res 33(1):37–41
Lobo CL, Bernardes RC, Santos FJ, Cunha-Vaz JG (1999) Mapping retinal fluorescein leakage with confocal scanning laser fluorometry of the human vitreous. Arch Ophthalmol 117(5):631–637
Open Access
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
About this article
Cite this article
Bali, E., Feron, E.J., Peperkamp, E. et al. Response to: The effect of a preoperative subconjunctival injection of dexamethasone on bloodretinal barrier breakdown following scleral buckling retinal detachment surgery. Graefes Arch Clin Exp Ophthalmol 249, 153 (2011). https://doi.org/10.1007/s00417-010-1412-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00417-010-1412-z