Imaging of the Ciliary Body: A Major Review

Figures & data

Table 1. Table showing interclass correlation coefficient, percentage agreement and κ value used by various authors.

ICC, % agreement and κ value	Authors
CBT2 (ICC = 0.96, 95% CI = 0.94–0.98,P < .001 CBT3 (ICC = 0.89, 95% CI = 0.83–0.93, p < .001)	Oliveira et al.^Citation25
% agreement Ciliary body size (82.14, with κ value 0.67–0.69) Ciliary sulcus (75%, with 89.29 κ value 0.56–0.80	Ku et al.^Citation17
κ value Ciliary body position: Inter-observer 0.654 Intra-observer 0.656 Ciliary body size: Inter-observer 0.654 Intra-observer 0.725	Jiang et al.^Citation22
ICC CBL: 0.91 (95% CI, 0.89–0.93)	Lincke et al.^Citation7

CBL: Ciliary body length, CBT2: Ciliary body thickness at 2 microns, CBT3: Ciliary body thickness at 3 microns, CI: Confidence intervals, ICC: Interclass correlation coefficient, κ: kappa, %: percentage.

Table 2. Table showing the illuminance used by various authors.

Illuminance (lux)	Authors
18–20	Garcia et al.^Citation9
200	Okamoto et al.^Citation8
326 ± 31 (Room light)	Sakata et al.^Citation20
0.86 ± 0.07 (1–2 mins after lights went off)	Sakata et al.^Citation20
Room light	Muftuoglu et al.,^Citation14 Gohdo et al.^Citation4
< 5	Jiang et al.^Citation22

Table 3. Table showing the different ciliary body parameters, with their definitions according to various authors.

Ciliary body parameters	Method of measurement	Authors
Maximum CBT, ciliary body size	“From the inner sclera to the apex of the ciliary body, maintaining perpendicularity to the scleral wall.”	Garcia et al.,^Citation9 Chen et al.,^Citation12 Liu et al., Jiang et al.,^Citation22 Ku et al.^Citation17
CBT	“Measured from the tip of the ciliary process to the sclera.”	Muftuoglu et al.^Citation14
CBT, CBT1	“Measured perpendicular to the inner scleral surface at a point 1 mm posterior to the scleral spur.”	Okamoto et al.,^Citation8 Sakata et al.,^Citation20 Mohamed Farouk et al.,^Citation23 Gohdo et al.,^Citation4 Kim et al.^Citation10
CBT2	“CBT measured at 2.0 mm posterior to the scleral spur.”	Mohamed Farouk et al.,^Citation23 Gohdo et al.,^Citation4 Oliveira et al.^Citation25
CBT3	“CBT measured at 3.0 mm posterior to the scleral spur.”	Mohamed Farouk et al.,^Citation23 Oliveira et al.^Citation25
CBT	“Maximum measurements of ciliary body thickness were obtained by applying the probe vertically on the corneoscleral limbus at the 6 o clock meridian”	Mishima et al.^Citation18
CBT1, CBT2, CBT3	“Thicknesses of the ciliary body measured at a distance of 1500 microns, 2000 microns and 2500 microns from the scleral spur”	Marchini et al.^Citation19
CBL	“A section of the arc passing through the scleral spur and the posterior end of the ciliary body.	Okamoto et al.^Citation8
CBL	“The distance in a straight line from the deepest point of the iridotrabecular angle to the last discernible mass of the ciliary body. The last discernible mass was defined as the region where there was no gap between the ciliary epithelium and the sclera and after this point, the ciliary body epithelium or internal limiting membrane/retina continued parallel to the sclera”	Lincke et al.^Citation7
CMT (Ciliary muscle thickness)	“Measured from the base of the ciliary process to the sclera”	Muftuoglu et al.,^Citation14 Safwat et al.^Citation26
Ciliary muscle (CM) CM25, CM50, CM75	“Width of the muscle determined at a point that fell 25%, 50% and 75% of the total length posterior to the scleral spur.”	Sheppard et al.^Citation13
CM2	“Ciliary muscle thickness at a set location 2 mm posterior to the scleral spur”	Sheppard et al.^Citation13
Ciliary muscle length (CML)	“Measurement from the scleral spur to posterior visible limit.”	Sheppard et al.^Citation13
CMAL (Ciliary muscle anterior length)	“Measurement from the point of maximum width of the ciliary body to the scleral spur.”	Sheppard et al.^Citation13
Scleral ciliary process angle (SCPA)	“Angle between the axis of the ciliary process and a line tangential to the sclera.”	Okamoto et al.,^Citation8 Okamoto et al.,^Citation27 Marchini et al.^Citation19
SCPA	“Angle between 2 lines, one being a line joining the sclera and a ciliary process and the other going through the plane of iris to the sclera. The point on the sclera being 500 microns from the scleral spur.”	Garudadri et al.^Citation3
Iris-ciliary angle (ICA)	“Angle between the posterior iris surface and the anterior surface of the ciliary body.”	Chen et al.^Citation12
Trabecular-ciliary angle (TCA)	“Angle measured by the scleral spur as the apex and the corneal endothelium and the anterior surface of the ciliary body as the arms.”	Chen et al.,^Citation12 He et al.^Citation24
Maximum CBT + ciliary process	“From the inner sclera to the apex of the ciliary processes, maintaining perpendicularity to the scleral wall.”	Garcia et al.^Citation9
CPT (ciliary process thickness)	“Measured from the tip to the base of the ciliary process,” where the mean of the 3 longest processes was taken.”	Muftuoglu et al.^Citation14
Ciliary process length (CP length)	“The distance from the innermost point of the ciliary body to the intersection point of the iris and ciliary body.”	Chen et al.^Citation12
Mean length of ciliary processes per field (MLCPPF; 5x5mm image)	“the sum of heights of ciliary processes (measured from the tip to the base of the ciliary process in microns) per field divided by number of ciliary processes in the same field”	Safwat et al.^Citation26
Mean width of ciliary processes per field (MWCPPF; 5x5mm image)	“the sum of widths of ciliary processes per field divided by number of ciliary processes per the same field”	Safwat et al.^Citation26
Ciliary process position	“Based on a pre-existing set of UBM images, it was “classified as neutral or anteriorly positioned based on the direction of the axis of the ciliary body.”	Jiang et al.^Citation22
Trabecular ciliary process distance (TCPD)	“Length of the line extending from the corneal endothelium 500 µm from the scleral spur perpendicularly to the line passing through the innermost point of the ciliary body and parallel to the iris.”	Chen et al.,^Citation12 Sakata et al.,^Citation20 He et al.,^Citation24 Liu et al.^Citation21
TCPD	“Vertical Distance of a ciliary process to the tangent drawn from 500 microns anterior to the scleral spur.”	Garudadri et al.^Citation3
Iris ciliary process distance (ICPD)	“From the posterior surface of the iris 500 microns anterior to the sclera spur toward the ciliary process.”	Liu et al.^Citation21

CBT: Ciliary body thickness, CBL: Ciliary body length, CM: Ciliary muscle, CMT: Ciliary muscle thickness, CML: Ciliary muscle length, CMAL: Ciliary muscle anterior length, SCPA: Scleral ciliary process angle, ICA: Iris ciliary angle, TCA: Trabecular ciliary angle, CPT: Ciliary process thickness, CPL: Ciliary process length, MLCPPF: Mean length of ciliary processes per field, MWCPPF: Mean width of ciliary processes per field, TCPD: Trabecular ciliary process distance, ICPD: Iris ciliary process distance.

Figure 1. Figure depicting ciliary body length (CBL) and ciliary body thickness (CBT). SS: scleral spur.

Table 4. Ciliary body thickness (CBT) and ciliary body length (CBL) in normal individuals.

Parameter	Mean (mm)	Authors
CBT	0.7 ± 0.1	Garcia et al.^Citation9
CBT	1.25 ± 0.16	Okamoto et al.^Citation8
CBT	1.21 ± 0.05	Muftuoglu et al.^Citation14
CBT	0.30 ± 0.04	Kim et al.^Citation10
CBT	1.21 ± 0.21	Okamoto et al.^Citation27
CBT	1.1 ± 0.25	Gupta et al.^Citation16
CBT1 (American Caucasian)	0.71 ± 0.10	He et al.^Citation24
CBT1 (Chinese)	0.65 ± 0.08	He et al.^Citation24
CBT1	0.60 ± 0.86	Gohdo et al.^Citation4
CBT2	0.362 ± 0.053	Oliviera et al.^Citation25
CBT2	0.32 ± 0.68	Gohdo et al.^Citation4
CBT3	0.247 ± 0.049	Oliviera et al.^Citation25
CBL	5.43 ± 0.58	Okamoto et al.^Citation8
CBL	5.76 ± 0.41	Okamoto et al.^Citation27
CBL (ASOCT)	3.351 ± 0.458	Lincke et al.^Citation7

CBT: Ciliary body thickness, CBL: Ciliary body length, ASOCT: Anterior segment optical coherence tomography, mm: millimetres.

Table 5. Trabecular ciliary process distance (TPCD), Trabecular ciliary angle (TCA) and Scleral ciliary process angle (SCPA).

Parameter	Type of eyes	Mean (mm)	Authors
TCPD	Normal	0.91 ± 0.2	Garudadri et al.^Citation3
TCPD	Normal, Caucasian	0.94 ± 0.02	He et al.^Citation24
TCPD	Normal Chinese	0.83 ± 0.02	He et al.^Citation24
TCA (American Caucasian)	Normal	85.0 ± 21.5	He et al.^Citation24
TCA (Chinese)	Normal	75.1 ± 17.9	He et al.^Citation24
SCPA	Normal	40.5 ± 5.7	Okamoto et al.^Citation8
SCPA	Normal	38.96 ± 7.39	Garudadri et al.^Citation3
SCPA	Controls	42.9 ± 4.42	Okamoto et al.^Citation27
SCPA	Aniridia	31.7 ± 3.26	Okamoto et al.^Citation27
SCPA	PACG	35.42 ± 7.24	Garudadri et al.^Citation3
SCPA	Subgroup narrow	35.76 ± 6.97	Garudadri et al.^Citation3
SCPA	Subgroup open	34.99 ± 7.78	Garudadri et al.^Citation3

TCPD: Trabecular ciliary process distance, TCA: Trabecular ciliary angle, SCPA: Scleral ciliary process angle, PACG: Primary angle closure glaucoma, mm: millimetres.

Table 6. Significant results related to CBT and CBL of normal subjects.

Significant results	P value	rho	Authors
“The ciliary body was thicker in the nasal quadrant than the temporal.”	0.02		Garcia et al.^Citation9
“Mean CBT was thicker in subjects above 40 years of age.”	0.04		Garcia et al.^Citation9
“Ethnicity was defined as a negative predictor for CBT1, Chinese had thinner CBT1.”	<0.001	−0.177	He et al.^Citation24
“Mean CBT2 and CBT3 was greater in myopes than in emmetropes or hyperopes”	<0.001		Oliveira et al.^Citation25
“Significant positive correlation between iris thickness and CBT.”	0.001	0.829	Okamoto et al.^Citation8
“Average CBL showed significant positive correlation with average CBT”	<0.001	0.40	Okamoto et al.^Citation8
“Average CBL correlated with Axial length.”	0.03	0.33	Okamoto et al.,^Citation8 Lincke et al.^Citation7
“Average CBL correlated with anterior chamber depth.”	0.05	0.23	Okamoto et al.^Citation8
“Average CBL correlated with trabecular iris angle.”	0.01	0.29	Okamoto et al.^Citation8
“Average CBL correlated with scleral-ciliary process angle.”	<0.001	0.40	Okamoto et al.^Citation8
“Mean CBL correlated significantly with age.”	<0.0001	0.11	Lincke et al.^Citation7
“The lens thickness was significantly correlated with CBT1 and CBT2.”	<0.001	0.34 0.43	Gohdo et al.^Citation4
“The anterior chamber depth was significantly correlated with CBT1 and CBT2”.	<0.001	0.48 0.56	Gohdo et al.^Citation4

CBT: Ciliary body thickness, CBL: Ciliary body length.

Figure 2. Figure depicting ciliary muscle thickness (CMT) and ciliary process thickness (CPT). SS: scleral spur.

Figure 3. Figure depicting ciliary muscle thickness at the levels of CM25, CM50 and CM75, as the width of the muscle determined at points that fell 25%, 50% and 75% of the total length posterior to the scleral spur. SS:scleral spur.

Figure 4. Figure depicting ciliary muscle length (CML) and ciliary muscle anterior length (CMAL). SS: scleral spur.

Figure 5. Figure depicting scleral ciliary process angle (SCPA) as described by Okamoto et al.⁸ and Garudadri et al.³ SS: scleral spur.

Figure 6. Figure depicting scleral ciliary process angle (SCPA), Trabecular ciliary angle (TCA), Iris ciliary angle (ICA), Trabecular ciliary process distance (TCPD) and Iris ciliary process distance (ICPD). SS: scleral spur.

Figure 7. Figure depicting the concept of long ciliary process. A line was drawn (line C) perpendicular to the plane of the iris and this line passed through a point 750 µm anterior to the scleral spur at the corneal endothelium. A long ciliary process was defined as one whose length crossed this line, and the ciliary sulcus was said to be absent if the ciliary processes were opposed to the peripheral iris at this same location. SS: scleral spur.

Table 7. Significant results related to angle closure.

Significant results	P value	Authors
“Compared with normal control eyes, narrow angle eyes showed a thinner ciliary body measurement 1 mm and 2 mm from the scleral spur.”	<0.001	Gohdo et al.^Citation4
“Ciliary body size was significantly different in size in the temporal quadrant between PACS and patients with open angles.”	0.013	Jiang et al.^Citation22
“The proportion of anteriorly positioned ciliary processes was higher than that of neutral ciliary body position in the cases (PACS).”	<0.001	Jiang et al.^Citation22
“Large ciliary body size have a moderate likelihood of having angle closure versus controls compared with small ciliary body size.”	0.007	Ku et al.^Citation17
“TCPD were higher in the normal patients as compared to PACG.”	<0.001	Garudadri et al.^Citation3

mm: millimetres, PACS: Primary angle closure suspect, TCPD: Trabecular ciliary process distance, PACG: Primary angle closure glaucoma.

Figure 8. Shows a uniquely thin, ill-defined and “rarefied” ciliary body, most probably owing to the stretching of the coats of the eye, with thinner ciliary body thickness (CBT) in congenital glaucoma.

Oliveira C, Tello C, Liebmann JM, Ritch R. Ciliary body thickness increases with increasing axial myopia. Am J Ophthalmol. 2005 Aug;140(2):324–325. doi:10.1016/j.ajo.2005.01.047.

 PubMed Web of Science ®Google Scholar

Ku JY, Nongpiur ME, Park J, et al. Qualitative evaluation of the iris and ciliary body by ultrasound biomicroscopy in subjects with angle closure. J Glaucoma. Dec 2014;23(9):583–588. doi:10.1097/IJG.0b013e318285fede.

 PubMed Web of Science ®Google Scholar

Jiang Y, He M, Huang W, Huang Q, Zhang J, Foster PJ. Qualitative assessment of ultrasound biomicroscopic images using standard photographs: the liwan eye study. Invest Ophthalmol Vis Sci. 2010 Apr;51(4):2035–2042. doi:10.1167/iovs.09-4145.

 PubMed Web of Science ®Google Scholar

Lincke J-B, Keller S, Amaral J, Zinkernagel MS, Schuerch K. Ciliary body length revisited by anterior segment optical coherence tomography: implications for safe access to the pars plana for intravitreal injections. Graefes Arch Clin Exp Ophthalmol. 2021 Jun;259(6):1435–1441. doi:10.1007/s00417-020-04967-3.

 PubMed Web of Science ®Google Scholar

Garcia JPS, Spielberg L, Finger PT. High-frequency ultrasound measurements of the normal ciliary body and iris. Ophthalmic Surg Lasers Imaging. 2011 Aug;42(4):321–327. doi:10.3928/15428877-20110603-03.

 PubMedGoogle Scholar

Okamoto Y, Okamoto F, Nakano S, Oshika T. Morphometric assessment of normal human ciliary body using ultrasound biomicroscopy. Graefes Arch Clin Exp Ophthalmol. 2017 Dec;255(12):2437–2442. doi:10.1007/s00417-017-3809-4.

 PubMed Web of Science ®Google Scholar

Sakata LM, Sakata K, Susanna R, et al. Long ciliary processes with no ciliary sulcus and appositional angle closure assessed by ultrasound biomicroscopy. J Glaucoma. Oct 2006;15(5):371–379. doi:10.1097/01.ijg.0000212251.72207.19.

 PubMed Web of Science ®Google Scholar

Muftuoglu O, Hosal BM, Zilelioglu G. Ciliary body thickness in unilateral high axial myopia. Eye (Lond). 2009 May;23(5):1176–1181. doi:10.1038/eye.2008.178.

 PubMed Web of Science ®Google Scholar

Gohdo T, Tsumura T, Iijima H, Kashiwagi K, Tsukahara S. Ultrasound biomicroscopic study of ciliary body thickness in eyes with narrow angles. Am J Ophthalmol. 2000 Mar;129(3):342–346. doi:10.1016/S0002-9394(99)00353-0.

 PubMed Web of Science ®Google Scholar

Chen Q, Tan W, Lei X, et al. Clinical prediction of excessive vault after implantable collamer lens implantation using ciliary body morphology. J Refract Surg. Jun 1 2020;36(6):380–387. doi:10.3928/1081597X-20200513-02.

 PubMed Web of Science ®Google Scholar

Mohamed Farouk M, Naito T, Shinomiya K, Mitamura Y. Observation of ciliary body changes during accommodation using anterior OCT. J Med Invest. 2018;65(1.2):60–63. doi:10.2152/jmi.65.60.

 PubMed Web of Science ®Google Scholar

Kim C, Yu HG. Changes in ciliary body thickness in patients with diabetic macular edema after vitrectomy. Retina. 2012 Jul;32(7):1316–1323. doi:10.1097/IAE.0b013e318236e81d.

 PubMed Web of Science ®Google Scholar

Mishima HK, Shoge K, Takamatsu M, Kiuchi Y, Tanaka J. Ultrasound biomicroscopic study of ciliary body thickness after topical application of pharmacologic agents. Am J Ophthalmol. 1996 Mar;121(3):319–321. doi:10.1016/S0002-9394(14)70282-X.

 PubMed Web of Science ®Google Scholar

Marchini G, Toscano A, Tosi R, Marraffa M, Bonomi L. Ultrasound biomicroscopy study of ciliary body and its influence on anterior chamber angle width. Acta Ophthalmol Scand Suppl. 1997;(224):27–28.

 PubMedGoogle Scholar

Safwat AMM, Hammouda LM, El-Zembely HI, Omar IAN. Evaluation of ciliary body by ultrasound bio-microscopy after trans-scleral diode cyclo-photocoagulation in refractory glaucoma. Eur J Ophthalmol. 2020 Nov;30(6):1335–1341. doi:10.1177/1120672119899904.

 PubMed Web of Science ®Google Scholar

Sheppard AL, Davies LN. In vivo analysis of ciliary muscle morphologic changes with accommodation and axial ametropia. Invest Ophthalmol Vis Sci. 2010 Dec;51(12):6882–6889. doi:10.1167/iovs.10-5787.

 PubMed Web of Science ®Google Scholar

Okamoto F, Nakano S, Okamoto C, Hommura S, Oshika T. Ultrasound biomicroscopic findings in aniridia. Am J Ophthalmol. 2004 May;137(5):858–862. doi:10.1016/j.ajo.2003.12.014.

 PubMed Web of Science ®Google Scholar

Garudadri CS, Chelerkar V, Nutheti R. An ultrasound biomicroscopic study of the anterior segment in Indian eyes with primary angle-closure glaucoma. J Glaucoma. 2002 Dec;11(6):502–507. doi:10.1097/00061198-200212000-00009.

 PubMed Web of Science ®Google Scholar

He N, Wu L, Qi M, et al. Comparison of ciliary body anatomy between American caucasians and ethnic Chinese using ultrasound biomicroscopy. Curr Eye Res. 2016;41(4):485–491. doi:10.3109/02713683.2015.1024869.

 PubMed Web of Science ®Google Scholar

Liu W, Qin L, Xu C, et al. Transscleral cyclophotocoagulation followed by cataract surgery: a novel protocol to treat refractory acute primary angle closure. BMC Ophthalmol. May 29 2020;20(1):209. doi:10.1186/s12886-020-01483-0.

 PubMed Web of Science ®Google Scholar

Gupta V, Jha R, Srinivasan G, Dada T, Sihota R. Ultrasound biomicroscopic characteristics of the anterior segment in primary congenital glaucoma. J AAPOS. 2007 Dec;11(6):546–550. doi:10.1016/j.jaapos.2007.06.014.

 PubMed Web of Science ®Google Scholar