March 2014
Volume 55, Issue 3
Letters to the Editor  |   March 2014
Choroidal Thickness Is Affected by More Factors Than Estimated
Author Affiliations & Notes
  • Yakup Aksoy
    Ophthalmology Department, Hakkari Military Hospital, Hakkari, Turkey;
  • Kadir Çolakoglu
    Ophthalmology Department, Kasımpasa Military Hospital, İstanbul, Turkey;
  • Taner Kar
    Ophthalmology Department, GATA Haydarpasa Training Hospital, İstanbul, Turkey;
  • Mehmet Koray Sevinc
    Ophthalmology Department, Gülhane Medical School, Ankara, Turkey; and the
  • Yusuf Emrah Eyi
    Emergency Department, Gülhane Medical School, Ankara, Turkey.
Investigative Ophthalmology & Visual Science March 2014, Vol.55, 1311. doi:
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    • Get Citation

      Yakup Aksoy, Kadir Çolakoglu, Taner Kar, Mehmet Koray Sevinc, Yusuf Emrah Eyi; Choroidal Thickness Is Affected by More Factors Than Estimated. Invest. Ophthalmol. Vis. Sci. 2014;55(3):1311.

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      © ARVO (1962-2015); The Authors (2016-present)

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We read the article ‘‘Choroidal Thickness in Unilateral Advanced Glaucoma” by Mwanza et al. 1 with a great interest. The authors aimed to investigate whether choroidal thickness (CT) measured using optical coherence tomography (OCT) in eyes with advanced glaucoma differs from that of fellow eyes with no or mild glaucoma. They concluded that there was no significant change in CT of eyes with advanced open-angle glaucoma compared with that of fellow eyes with no glaucoma or with mild glaucoma. We congratulate the authors for their enlightening study about this controversial subject related to glaucoma and CT. We would like to make some contributions to the study. 
There are many factors that may affect CT, such as myopia, intraocular surgery, diabetic retinopathy, age-related macular degeneration, central serous chorioretinopathy, and laser therapy. In this study, the subjects with these factors have been excluded. Aside from this, some studies also reported that sildenafil citrate ingestion produced a significant increase in choroidal thickness, as measured by spectral domain OCT. Intravenous acetazolamide also increases choroidal thickness and there are a number of other vasoactive substances with potential influence on the choroid. 24 The authors didn't indicate whether any subject had such a medication or not. We think that this kind of medication may affect the choroid and change the results. 
Additionally, CT shows a significant diurnal variation. Studies have shown that the choroid thickens the most around midnight and thins the most around noon. This change was between approximately 30 and 60 μm. 5,6 In this present study of Mwanza et al., 1 measurement time is not taken into account. We think that the results would be different if all measurements had been performed at noon or midnight. To ensure consistency and minimize any influence from potential diurnal fluctuation in CT, all measurements should be performed at the same time of day. 
Mwanza JC Sayyad FE Budenz DL. Choroidal thickness in unilateral advanced glaucoma. Invest Ophthalmol Vis Sci . 2012; 53: 6695–6701. [CrossRef] [PubMed]
Vance SK Imamura Y Freund KB. The effects of sildenafil citrate on choroidal thickness as determined by enhanced depth imaging optical coherence tomography. Retina . 2011; 31: 332–335. [CrossRef] [PubMed]
Dallinger S Bobr B Findl O Eichler HG Schmetterer L. Effects of acetazolamide on choroidal blood flow. Stroke . 1998; 29: 997–1001. [CrossRef] [PubMed]
Bogner B Tockner B Runge C The effect of vasopressin on choroidal blood flow, intraocular pressure, and orbital venous pressure in rabbits. Invest Ophthalmol Vis Sci . 2011; 52: 7134–7140. [CrossRef] [PubMed]
Tan CS Ouyang Y Ruiz H Sadda SR. Diurnal variation of choroidal thickness in normal, healthy subjects measured by spectral domain optical coherence tomography. Invest Ophthalmol Vis Sci . 2012; 53: 261–266. [CrossRef] [PubMed]
Brown JS Flitcroft DI Ying GS In vivo human choroidal thickness measurements: evidence for diurnal fluctuations. Invest Ophthalmol Vis Sci . 2009; 50: 5–12. [CrossRef] [PubMed]

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