J Korean Ophthalmol Soc JKOS Journal of the Korean Ophthalmological Society 0378-6471 2092-9374 The Korean Ophthalmological Society 10.3341/jkos.2020.61.1.69 Original Article Long-term Longitudinal Changes in Choroidal Thickness with Intraocular Pressure Reduction after Glaucoma Surgery Kim Inhye MD 1 Gu Won Mo MD 2 Jeong Areum MD 1 Cha Soon Cheol MD PhD 1 Department of Ophthalmology, Yeungnam University College of Medicine, Daegu, Korea. Daegu Premier Eye Center, Daegu, Korea. Address reprint requests to Soon Cheol Cha, MD, PhD. Department of Ophthalmology, Yeungnam University Hospital, #170 Hyeonchung-ro, Nam-gu, Daegu 42415, Korea. Tel: 82-53-620-3442, Fax: 82-53-626-5936, sccha@ynu.ac.kr 01 2020 15 01 2020 61 1 69 77 16 05 2019 23 07 2019 30 12 2019 ©2020 The Korean Ophthalmological Society 2020 The Korean Ophthalmological Society This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose

We investigated the long-term longitudinal changes in axial length (AL), mean ocular perfusion pressure (MOPP), and choroidal thickness (CT) according to the reduction of intraocular pressure (IOP) after glaucoma surgery. The potential variables associated with CT changes were also evaluated.

 Methods

This was a prospective study for 1 year after glaucoma surgery, which included 71 eyes of 71 patients with primary open-angle glaucoma. The subfoveal CT (SFCT) and peripapillary CT (PPCT) were measured using spectral-domain optical coherence tomography preoperatively and 1 week, 1 month, 2 months, 6 months, and 1 year postoperatively. MOPP was calculated from the IOP and blood pressure. The AL was measured using partial coherence interferometry. Regression analysis was conducted to assess the possible association of variables.

 Results

The AL decreased and the MOPP, SFCT, and PPCT increased significantly with IOP reduction at 1 year post-operatively (all, p < 0.001). The changes in SFCT and PPCT were significantly associated with IOP reduction at 1 year postoperatively (r = −0.519 and r = −0.528, respectively). Importantly, greater increases in SFCT and PPCT were found in patients with IOP reduction more than 30% from baseline, when compared with those with less than 30% reduction (p = 0.001 and p = 0.002, respectively). The SFCT increased more significantly in patients with AL ≤ 24 mm, compared with patients with AL > 24 mm (p = 0.044).

 Conclusions

Reduction in the IOP, increase in the MOPP, decrease in the AL, and increase in the CT after glaucoma surgery persisted for 1 year during a long-term follow-up. These results suggested that glaucoma surgery reduced mechanical compression on the optic nerve fiber and increased intraocular blood flow.

 Axial length Choroidal thickness Glaucoma surgery Intraocular pressure Ocular perfusion pressure

The authors have no conflicts to disclose.

 Hyman L Wu SY Connell AM Prevalence and causes of visual impairment in The Barbados Eye Study Ophthalmology 2001 108 1751 1756 Quigley HA Broman AT The number of people with glaucoma worldwide in 2010 and 2020 Br J Ophthalmol 2006 90 262 267 Hayreh SS Blood supply of the optic nerve head and its role in optic atrophy, glaucoma, and oedema of the optic disc Br J Ophthalmol 1969 53 721 748 Duijm HF van den Berg TJ Greve EL Choroidal haemodynamics in glaucoma Br J Ophthalmol 1997 81 735 742 Grunwald JE Piltz J Hariprasad SM DuPont J Optic nerve and choroidal circulation in glaucoma Invest Ophthalmol Vis Sci 1998 39 2329 2336 Schulzer M Intraocular pressure reduction in normal-tension glaucoma patients. The Normal Tension Glaucoma Study Group Ophthalmology 1992 99 1468 1470 Heijl A Leske MC Bengtsson B Reduction of intraocular pressure and glaucoma progression: results from the Early Manifest Glaucoma Trial Arch Ophthalmol 2002 120 1268 1279 Kass MA Heuer DK Higginbotham EJ The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma Arch Ophthalmol 2002 120 701 713 discussion 829-30 Leske MC Heijl A Hussein M Factors for glaucoma progression and the effect of treatment: the early manifest glaucoma trial Arch Ophthalmol 2003 121 48 56 Shaarawy T Sherwood M Hitchings R Crowston J Galucoma 2nd ed London Elsevier Saunders 2015 Vol. 1 57 66 Mwanza JC Hochberg JT Banitt MR Lack of association between glaucoma and macular choroidal thickness measured with enhanced depth-imaging optical coherence tomography Invest Ophthalmol Vis Sci 2011 52 3430 3435 Kim M Kim SS Kwon HJ Association between choroidal thickness and ocular perfusion pressure in young, healthy subjects: enhanced depth imaging optical coherence tomography study Invest Ophthalmol Vis Sci 2012 53 7710 7717 Spaide RF Koizumi H Pozzoni MC Enhanced depth imaging spectral-domain optical coherence tomography Am J Ophthalmol 2008 146 496 500 Barbosa CP Stefanini FR Penha F Intraocular pressure and ocular perfusion during hemodialysis Arq Bras Oftalmol 2011 74 106 109 Schmidl D Weigert G Dorner GT Role of adenosine in the control of choroidal blood flow during changes in ocular perfusion pressure Invest Ophthalmol Vis Sci 2011 52 6035 6039 Cashwell LF Martin CA Axial length decrease accompanying successful glaucoma filtration surgery Ophthalmology 1999 106 2307 2311 Uretmen O Ateş H Andaç K Deli B Axial length changes accompanying successful nonpenetrating glaucoma filtration surgery Ophthalmologica 2003 217 199 203 Németh J Horóczi Z Changes in the ocular dimensions after trabeculectomy Int Ophthalmol 1992 16 355 357 Kook MS Kim HB Lee SU Short-term effect of mitomycin-C augmented trabeculectomy on axial length and corneal astigmatism J Cataract Refract Surg 2001 27 518 523 Berisha F Schmetterer K Vass C Effect of trabeculectomy on ocular blood flow Br J Ophthalmol 2005 89 185 188 Yamazaki Y Hayamizu F Effect of trabeculectomy on retrobulbar circulation and visual field progression in patients with primary open-angle glaucoma Clin Ophthalmol 2012 6 1539 1545 Kara N Baz O Altan C Changes in choroidal thickness, axial length, and ocular perfusion pressure accompanying successful glaucoma filtration surgery Eye (Lond) 2013 27 940 945 Flammer J Orgül S Costa VP The impact of ocular blood flow in glaucoma Prog Retin Eye Res 2002 21 359 393 Bayhan HA Bayhan SA Can I Evaluation of the macular choroidal thickness using spectral optical coherence tomography in pseudoexfoliation glaucoma J Glaucoma 2016 25 184 187 Nickla DL Wallman J The multifunctional choroid Prog Retin Eye Res 2010 29 144 168 Polska E Simader C Weigert G Regulation of choroidal blood flow during combined changes in intraocular pressure and arterial blood pressure Invest Ophthalmol Vis Sci 2007 48 3768 3774 Saeedi O Pillar A Jefferys J Change in choroidal thickness and axial length with change in intraocular pressure after trabeculectomy Br J Ophthalmol 2014 98 976 979 Maul EA Friedman DS Chang DS Choroidal thickness measured by spectral domain optical coherence tomography: factors affecting thickness in glaucoma patients Ophthalmology 2011 118 1571 1579 Sızmaz S Küçükerdönmez C Pınarci EY The effect of smoking on choroidal thickness measured by optical coherence tomography Br J Ophthalmol 2013 97 601 604 Moschos MM Nitoda E Laios K The impact of chronic tobacco smoking on retinal and choroidal thickness in greek population Oxid Med Cell Longev 2016 2016 2905789 Leske MC Ocular perfusion pressure and glaucoma: clinical trial and epidemiologic findings Curr Opin Ophthalmol 2009 20 73 78 Margolis R Spaide RF A pilot study of enhanced depth imaging optical coherence tomography of the choroid in normal eyes Am J Ophthalmol 2009 147 811 815 Agawa T Miura M Ikuno Y Choroidal thickness measurement in healthy Japanese subjects by three-dimensional high-penetration optical coherence tomography Graefes Arch Clin Exp Ophthalmol 2011 249 1485 1492 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 Lee SW Yu SY Seo KH Diurnal variation in choroidal thickness in relation to sex, axial length, and baseline choroidal thickness in healthy Korean subjects Retina 2014 34 385 393 Lichter PR Musch DC Gillespie BW Interim clinical outcomes in the Collaborative initial Glaucoma Treatment Study comparing initial treatment randomized to medications or surgery Ophthalmology 2001 108 1943 1953 Collaborative Normal-Tension Glaucoma Study Group Comparison of glaucomatous progression between untreated patients with normal-tension glaucoma and patients with therapeutically reduced intraocular pressures Am J Ophthalmol 1998 126 487 497 The AGIS Investigators The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration Am J Ophthalmol 2000 130 429 440 Sanchez-Cano A Orduna E Sequra F Choroidal thickness and volume in healthy young white adults and the relationships between them and axial length, ammetropy and sex Am J Ophthalmol 2014 158 574 583 Obtaining choroidal thickness (CT). The choroid is seen in cross-section on an enhanced-depth imaging optical coherence tomography scan. CT is defined as space between up-pointing arrow and down-pointing arrow. The outer border of the retinal pigment epithelium to the inner border of the sclera (arrowheads). (A) The subfoveal choroidal thickness (SFCT); SFCT was measured at subfovea, 250 µm nasal to the fovea, and 250 µm temporal to the fovea. (B-D) The peripapillary choroidal thickness (PPCT); PPCT was measured at 1,000 µm nasal and temporal side (B), superior (C) and inferior side (D) from the optic disc center. Scatter spot showing associations of changes in intraocular pressure (IOP) and choroidal thickness (CT) at preoperative and 1 year postoperative. (A) Changes in IOP and subfoveal CT at preoperative and 1 year postoperative showed a significant negative correlation (r = −0.519, <italic>p</italic> < 0.001). (B) Changes in IOP and peripapillary choroidal thickness at preoperative and 1 year postoperative showed a significant negative correlation (r = −0.528, <italic>p</italic> < 0.001). SFCT = subfoveal choroidal thickness; PPCT = peripapillary choroidal thickness. <sup>*</sup>Simple correlation analysis. Baseline demographics and clinical characteristics of subjects (n = 71)

Categorical variables are reported using proportions and continuous variables are reported using mean ± standard deviation (range) or number (%) unless otherwise indicated.

SE = spherical equivalent; HTN = hypertension; DM = diabetic mellitus.

 One-year longitudinal changes of ocular parameter at preoperative and postoperative periods

Values are presented as mean ± standard deviation (range).

IOP = intraocular pressure; AL = axial length; MOPP = mean ocular perfusion pressure; SFCT = subfoveal choroidal thickness; PPCT = peripapillary choroidal thickness.

*Repeated measured analysis of variance.

 Analyses of potential factors associated with changes in choroidal thickness at 1 year postoperatively

SFCT = subfoveal choroidal thickness; PPCT = peripapillary choroidal thickness; HTN = hypertension; DM = diabetic mellitus; IOP = intraocular pressure; AL = axial length; MOPP = mean ocular perfusion pressure; Preop = preoperative; ED = eye drop; postop = postoperative.

*Simple linear regression analysis; †multiple linear regression analysis.

 Changes in ocular parameters according to amount of IOP reduction at 1 year postoperatively

Values are presented as mean ± standard deviation.

IOP = intraocular pressure; postop = postoperative; SFCT = subfoveal choroidal thickness; PPCT = peripapillary choroidal thickness; AL = axial length.

*Subgroup with intraocular pressure reduction more than 30% from the baseline IOP; †subgroup with intraocular pressure reduction less than or equal to 30% from the baseline IOP; ‡independent-sample t-test.

 Changes in ocular parameters according to baseline axial length at 1 year postoperatively

Values are presented as mean ± standard deviation.

AL = axial length; IOP = intraocular pressure; SFCT = subfoveal choroidal thickness; PPCT = peripapillary choroidal thickness.

*Subgroup with preoperative axial length less than or equal to 24 mm; †subgroup with preoperative axial length greater than 24 mm; ‡independent-sample t-test.