
==== Front
BMC Ophthalmol
BMC Ophthalmol
BMC Ophthalmology
1471-2415
BioMed Central London

3646
10.1186/s12886-024-03646-9
Research
Precise prediction of size of a foldable capsular vitreous body via computerized three-dimensional ocular reconstruction in severe retinal detachment
Long Chongde 1
Gao Qianying 2
Liu Shenwen 3
Chen Yan 4
Song Huping 5
Yu Jinguo 6
Lou Bingsheng 1
Yuan Zhaohui 1
Zheng Yongxin 1
Zhong Liuxueying 1
Qiao Siqi 2
Meng Xiangda 6
Liu Yuanyuan 6
Wang Yingyu 2
Liu Yuanyuan 2
Lin Xiaofeng linxiaof@mail.sysu.edu.cn

7
Yan Hua zyyyanhua@tmu.edu.cn

68910
1 grid.12981.33 0000 0001 2360 039X State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Sun Yat-sen University, Guangzhou, 510060 China
2 Vesber Vitreous Institute, Guangzhou, 510060 China
3 Shenzhen Eye Hospital, Shenzhen, China
4 https://ror.org/00mcjh785 grid.12955.3a 0000 0001 2264 7233 Xiamen Eye Center of Xiamen University, Xiamen, China
5 Xi’an People’s Hospital (Xi’an Fourth Hospital), Xian, China
6 https://ror.org/003sav965 grid.412645.0 0000 0004 1757 9434 Tianjin Medical University General Hospital, Tianjin, China
7 Aier Ophthalmology Institute, Aier Mansion, No.188 South Furong Road, Changsha City, Hunan province China
8 https://ror.org/02mh8wx89 grid.265021.2 0000 0000 9792 1228 Laboratory of Molecular Ophthalmology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
9 https://ror.org/01y1kjr75 grid.216938.7 0000 0000 9878 7032 Medical School of Nankai University, Tianjin, China
10 https://ror.org/003sav965 grid.412645.0 0000 0004 1757 9434 Department of Ophthalmology, Tianjin Medical University General Hospital Medical School of Nankai University, Tianjin, 300052 China
20 9 2024
20 9 2024
2024
24 4125 5 2023
19 8 2024
© The Author(s) 2024
2024
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Background

This study aimed to precisely predict the size and silicone oil injection of a foldable capsular vitreous body (FCVB) via computerized three-dimensional (3D) ocular reconstruction in the treatment of severe retinal detachment in China.

Methods

The 3D software Unigraphics NX was applied to determine the volume of the inner cavity with 16–30 mm axial length, assigning the anterior and posterior chambers, the FCVB sizes, and the silicone oil injection volume, and modeling the data between the axial length and the FCVB size. In clinical practice, IOL Master was applied to accurately measure the axial length of the contralateral healthy eye to anchor the anterior-posterior and horizontal diameters of the operated eye in horizontal position CT, and compared with the model to recommend the FCVB size and silicone oil amount, and the clinical effect was validated in cases across five hospitals in China.

Results

For the axial length of 16–30 mm, the volume of the inner cavity is 1.2 ml-8.4 ml. FCVB size and silicone oil volume were recommended based on this volume of the inner cavity. Of 253 cases, we noted 11 cases implanted with AV-10P and 1.05 ± 0.21 ml of silicone oil, 41 with AV-12P and 1.58 ± 0.18 ml of silicone oil, 163 with AV-13.5P and 2.48 ± 0.29 ml of silicone oil, 31 with AV-15P and 3.57 ± 0.39 ml of silicone oil, and 7 with AV-17P and 5.71 ± 0.81 ml of silicone oil. There was no significant difference in postoperative visual acuity scores compared with preoperative (P = 0.097), postoperative IOP(10.29 ± 0.57mmHg)was slightly higher than preoperative IOP (9.76 ± 0.48 mmHg), but there was still no statistically significant difference between the two comparisons (P = 0.405).

Conclusion

Three-dimensional reconstruction prediction is a good solution for eyeballs with obvious individualized changes in severe retinal detachment, and this method helps doctors standardize FCVB size selection and the silicone oil amount for patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-024-03646-9.

Keywords

FCVB
3D reconstruction
Silicone oil
Retinal detachment
issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
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pmcIntroduction

In 1962, Cibis introduced silicone oil into ophthalmology for the treatment of severe eye trauma and complex retinal detachment [1–5]. Silicone oil must be removed after 3–6 months in the eye; otherwise, it causes cataracts, keratopathy, silicone oil emulsification or migration, glaucoma, or other complications [6–8]. Furthermore, silicone oil may enter the ciliary body and damage its functioning [9, 10], leading to low intraocular pressure (IOP) and oil- dependent eyes. Some patients cannot tolerate the pain associated with these complications and this eventually leads to eye removal, which causes patients severe psychological and physical damage [11].

A foldable capsular vitreous body (FCVB) is composed of a drainage valve, a drainage tube, and a capsule. The capsule is designed using a computer to simulate the shape of a natural vitreous body [12–18]. The capsule can isolate the aqueous humor from the silicone oil reaction and prevent emulsification. A second-generation FCVB with a plano-lens surface can maintain the posterior chamber space without interfering with the ciliary body. Therefore, silicone oil cannot migrate into the ciliary body. The function of the ciliary body can slowly recover, maintaining intraocular pressure and preserving the structure and part of the function of the eye, and avoiding the need for eye extraction [19–25].

In clinical practice, five sizes of FCVB ( AV-10P, AV-12P, AV-13.5P, AV-15P, AV-17P, AV stands for artificial vitreous, The numbers 10, 12, 13.5, 15, and 17 represent the anteroposterior diameters of the vitreous cavity respectively and P signifies that the FCVB lens surface is plane) have been designed to match the individual vitreous cavities resulting from severe ocular trauma. The improper selection of sizes or excessive silicone oil injection leads to complications such as anterior-segment ischemia, a shallow anterior chamber, or corneal edema [19–25]. Three-dimensional computer reconstruction is an effective method for preoperative evaluation and avoiding postoperative complications. With the rapid development of medical imaging equipment and computer hardware, 3D medical image-reconstruction technology has begun to be widely used in diagnostic medicine, anatomy, and other medical fields [26, 27]. Since the orbit is easily measured using computerized tomography (CT) imaging, this study aimed to accurately predict the FCVB size and silicone oil injection amount before surgery by using 3D computer reconstruction and to verify its practical application effect.

Methods

Three-dimensional reconstruction modeling of inner ocular cavity capacity in healthy and atrophied eyes

Knowing the anterior–posterior, vertical, and horizontal diameters of the eye shell, we drew an eyeball sphere using the 3D software Unigraphics NX. Approximately 3 mm of the outer shell’s ocular tissue (cornea, choroid, retina, and sclera) was subtracted from this eyeball sphere. Next, the volume calculated from these values in Unigraphics NX was used to determine the capacity of the inner ocular cavity.

For an emmetropia, a simulated eye model with an anterior–posterior, vertical, and horizontal diameter of 23.5 mm was created and drawn as an example, resulting in an intraocular cavity diameter of 20.5 mm, which gave an inner ocular cavity capacity of approximately 4.5 mm3, as shown in Fig. 1. If the same method was applied to the eye axis as to a 21.5-millimeter atrophied eyeball, it would provide an inner ocular cavity capacity of approximately 3.3 mm3.Fig. 1 Computerized 3D reconstruction of the stereoscopic view. A Drawing of a simulated eye with an anterior-posterior, horizontal, and vertical diameter of 23.5 mm. B Removing 3 mm of tissue thickness from the eye’s outer shell to obtain an inner ocular cavity diameter of 20.5 mm. C Deriving an inner ocular cavity capacity of 4.5 mm3

Three-dimensional reconstruction modeling of anterior chamber, posterior chamber, FCVB capsule, and silicone oil injection based on inner ocular cavity capacity

Assuming a FCVB-implanted eye, the inner ocular cavity capacity is composed of the anterior chamber, the posterior chamber, the FCVB capsule, and the silicone oil tamponade. Since the anterior and posterior chambers are basically stable, the silicone oil volume is easily calculated after measuring the volume of the FCVB capsule.

Refer to the following formula: recommended volume of silicone oil = volume of the inner cavity capacity - anterior chamber space - posterior chamber space - the volume of the FCVB capsule itself.

Inner ocular cavity capacity calculation in Practice based on the Contralateral Eye

In clinical reality, most patients are injected in the eye with silicone oil before FCVB implantation. Thus, it is quite challenging to measure the exact anterior–posterior diameter of the eye using either an ultrasound or an intraocular lens (IOL) Master (Cari Zeiss, IOLMASTER 500), meaning that the eye’s inner-space volume cannot be calculated. To solve this problem, we used CT to measure the eye’s anterior-posterior, vertical, and horizontal diameters.

However, due to the poor accuracy of CT compared to an A-scan ultrasound or IOL Master, we anchored the CT image of the healthy eye with an A-scan ultrasound to obtain the anterior-posterior, vertical, and horizontal diameters of the treated eye at the same magnification. Inner ocular cavity capacity was then obtained to calculate the anterior and posterior chamber space volumes and FCVB size and to derive the recommended silicone oil volume.

Horizontal CT eye axis measurement

Keep the patient lying flat with no tilt, keeping both eyes on the same level;

Set the slice-thickness layer as 2 mm for scanning and save the examination map;

Perform CT numerical measurement;

Enter the image storage and transmission system (PACS), and medical HIS information system, find the patient’s CT examination map, and tap on it so that the cross-sectional maximum map appears, as shown in Fig. 2;Fig. 2 Schematic diagram of the CT inspection

Consider the left eye in Fig. 3A. The anterior-posterior diameter of the eye is the distance from point a (from the anterior apex of the cornea) to point b (behind the sclera next to the optic nerve), and the horizontal diameter is the distance from point c to point d;Fig. 3 Straightedge measurement of the ocular axis of the treated eye (from the anterior vertex of the cornea to the posterior vertex of the sclera). A The largest cross-sectional area (largest lens area, with optic nerve) selected from the CT examination image. B Contralateral axis length by IOL Master. C Straightedge measurement of the ocular axis of the contralateral eye. D Straightedge measurement of the ocular axis of the surgical eye

Measure the horizontal diameter and anterior-posterior diameter of the eye in turn;

After the test is completed, the data appear in the lower right-corner.

The spatial volume of the treated eye is obtained by comparing the spatial volume of the anchored healthy eye

Computed tomography values are currently measured by imaging doctors who are not experts in how ophthalmologists measure anterior-posterior, horizontal, and vertical diameters, and the errors in the measured values are relatively large; thus, the diameters must be measured by ophthalmologists to an accuracy of 0.5 mm.

In patients with ocular trauma, the accuracy of direct CT measurements of the anterior–posterior and horizontal diameters of the eye is poor. Therefore, we anchored the spatial volume of the healthy eye for comparison to determine the spatial volume of the treated eye.

In clinical practice, the vertical diameter of the eye is essentially the same as the horizontal diameter; it is possible to use the horizontal diameter instead of the vertical diameter to derive the spatial volume.

We performed the following steps:

Measurement of the anterior-posterior and horizontal diameters of the healthy eye using an A-scan ultrasound or IOL Master.

Calibration of the anterior-posterior and horizontal diameters of the healthy eye in the CT examination image. As shown in Fig. 3A, the largest cross-sectional area (largest lens area, with optic nerve) was selected from the CT examination image and measured on a mobile phone using a straight edge, and the CT image was enlarged or reduced until it reached the value measured with the A-scan ultrasound or IOL Master, as shown in Fig. 3B.

Measuring the anterior-posterior and horizontal diameters of the treated eye in the CT image: at the same magnification, the anterior-posterior and horizontal diameters of the treated eye can be obtained using a straight edge, as shown in Fig. 3C and D. The volume of the inner chamber of the eye was calculated using the 3D reconstruction model of the inner chamber of the eye to obtain the size of the FCVB and the recommended volume of silicone oil.

Obtain the anterior-posterior and horizontal diameters of the treated eye, and then derive the size of the FCVB and the recommended volume of silicone oil

National data collection in reality

Data were collected from doctors at FCVB surgical sites nationwide. FCVB is manufactured by Guangzhou Vesber Biotechnology CO., Ltd., divided into AV-10P, AV-12P, AV-13.5P, AV-15P, AV-17P, total five sizes. FCVB raw material is made of silicone, including vitreous-like capsule, drain tube, drain valve, the vitreous-like capsule with a specific lens surface design what is programmed by computer to accurately simulate the parameters of the vitreous cavity. Based on the IOL Master or A-Scan values provided for the healthy eye and the horizontal-bit raw CT images, the method described above was applied to determine the recommended FCVB size, volume of silicone oil, and predicted anterior and posterior chamber spaces.

Given that the vast majority of FCVB patients have poor preoperative ciliary function and low atrial-fluid production, they are prone to having a shallow anterior chamber postoperatively. Based on practical experience, the anterior-posterior chamber space of the treated eye should be filled with viscoelastic material before the end of the procedure to aid the slow recovery of ciliary function. The anterior-posteriorchamber space is essentially deterministic, in that it determines the recommended viscoelastic filling volume.

The doctors received the necessary information and operated according to the recommended values. All patients had a precise diagnosis and therefore underwent pars plana vitrectomy (PPV) and FCVB implantation. Patient case information was collected and parameters were recorded.

Clinical outcome feedback

The inclusion criteria, exclusion criteria, and treatment procedures were described previously [18–25]. Briefly, inclusion criteria included severe ocular trauma and silicone-oil-dependent eyes that could not be treated with existing vitreous substitutes ((a) Severe unilateral ocular perforating injuries, compounded retinal or choroidal detachments resulting from retinal rupture or retinal choroidal hemorrhage, retinal or choroidal defect resulting from severe unilateral ocular rupture injuries. (b) Severe unilateral rupture injury of the eyeball resulting in retinal and/or choroidal defects. (c) Giant posterior scleral rupture injuries that cannot be repaired. (d) Silicone oil cannot be taken out for a long time with incomplete retinal reattachment. (e) Undergone retinal detachment surgery and silicone oil tamponade twice or more. However, the retina is re-detached after silicone oil removal.). Exclusion criteria included severe intraocular infections, uveitis, or intraorbital infections. After PPV surgery, an incision of approximately 4–4.5 mm was made on the sclera 5 mm away from the corneal limbus. A FCVB was properly folded and implanted into the eyeball cavity through the incision using a push injector or forceps. The silicone oil was slowly injected into the capsule through the drainage valve. The scleral incision was sutured and a drainage tube was ligated and fixed to the sclera. The main FCVB surgical implantation steps (as shown in Fig. 4), including leakage test, folding, scleral incision creation, implantation, silicone oil injection, and closure of scleral incision were described in previous studies [18–25].Fig. 4 The procedure of FCVB implantation. A Inject sterile air into the balloon; B Vacuum the balloon; C Fold the balloon into three layers; D Fit into the implant; E Make a scleral incision; F Implant the product; G Close a suture on each side of the drain; H Inject silicone oil; I Inject viscoelastic; J Close the scleral incision; K Ligate the drain; L Close the conjunctival incision

Each patient underwent a detailed eye examination before and 1 week, 6 months, and 12 months after surgery, mainly including assessment of best-corrected visual acuity, IOP (noncontact ophthalmometry), anterior segment (TOMEY, CASIA2) and macular optical coherence tomography (Heidelberg, Spectralis HRA + OCT), color -fundus photography, orbital CT, and ocular complications. Visual acuity was graded according to the following system: no light perception (NLP), 0; light perception(LP) 1; hand motion perception (HM), 2; finger count perception (FC), 3; 0.05 acuity, 4; and 0.1 acuity, 5 [15].

Statistics analysis

Data are reported as mean ± standard deviation (SD). The preoperative and postoperative visual acuity and intraocular pressure were compared using a Paired t-test and analyzed using SPSS software.

Results

Healthy and atrophic eyes

As shown in Table 1, the inner ocular cavity capacity of a healthy eye is 4.5 mm3. As the eye axis becomes smaller, the capacity of the eye cavity gradually becomes smaller in turn, just as when the axes of some myopias far exceed healthy limits, the eye cavity capacity gradually increases. The interval gradient was selected as 1 mm in the 16-20- millimeter and 26-30-millimeter intervals, and the value gradient was calibrated to a 0.5-millimeter gradient in the 20-26-millimeter interval. Table 1 Basis for measurement of inner ocular cavity capacity

Anterior-posterior diameter of eyeball（mm）	Horizontal diameter of eyeball（mm）	Vertical diameter of eyeball（mm）	inner ocular cavity capacity（mL）	Measurement data of inner ocular cavity capacity（mm*mm）	
16	16	16	1.2	13*13*13	
17	17	17	1.4	14*14*14	
18	18	18	1.7	14.5*15*15	
＜20	<20	<20	2.0	15.5*16*16	
20	20	20	2.45	16.5*17*17	
20.5	20.5	20.5	2.7	17*17.5*17.5	
21	21	21	2.9	17.5*18*18	
<21.5	<21.5	<21.5	3.1	18*18.5*18.5	
21.5	21.5	21.5	3.3	18.5*18.5*18.5	
22	22	22	3.6	19*19*19	
22.5	22.5	22.5	3.8	19.5*19.5*19.5	
23	23	23	4.1	20*20*20	
<23.5	<23.5	<23.5	4.2	20*20*20	
23.5	23.5	23.5	4.5	20.5*20.5*20.5	
24	24	24	4.8	21*21*21	
24.5	24.5	24.5	5.2	21.5*21.5*21.5	
25	25	25	5.5	22*22*22	
25.5	25.5	25.5	5.8	22*22*22	
<26	<26	<26	6.0	22.5*22.5*22.5	
26	26	26	6.4	23*23*23	
27	26.5	26.5	7.0	24*23.5*23.5	
28	27	27	7.7	25*24*24	
29	27.5	27.5	8.4	26*24.5*24.5	

Recommended FCVB size and silicone oil injection based on inner ocular cavity capacity

The recommended FCVB size was determined according to the patient’s eye axis, with five FCVB sizes available: AV-10P, AV-12P, AV-13.5P, AV-15P, and AV-17P.

It was necessary to determine the volume of the FCVB capsule after implantation. The capsule volumes of the five FCVB sizes were determined to be 0.18 ml, 0.20 ml, 0.25 ml, 0.3 ml, and 0.4 ml, respectively (see Table 2). Table 2 Recommended FCVB size and volume of silicone oil according to eye axis

Anterior-posterior diameter of eyeball（mm）	Horizontal diameter of eyeball（mm）	Recommended size of products	Recommended volume of anterior chamber viscoelastic agent（mL）	Recommended volume of posteior chamber viscoelastic agent（mL）	Recommended volume of solicone oil（mL）	Filling volume of FCVB（mL）	
16	16	AV-10P	0.15	0.2	0.7	0.18	
17	17	0.2	0.35	0.8	0.18	
18	18	0.2	0.4	0.9	0.18	
<20	<20	0.2	0.5	1.1	0.18	
20	20	AV-12P	0.3	0.55	1.4	0.2	
20.5	20.5	0.3	0.6	1.6	0.2	
21	21	0.3	0.6	1.8	0.2	
<21.5	<21.5	0.3	0.6	2.0	0.2	
21.5	21.5	AV-13.5P	0.3	0.6	2.2	0.25	
22	22	0.3	0.6	2.5	0.25	
22.5	22.5	0.3	0.6	2.7	0.25	
23	23	0.3	0.6	2.9	0.25	
<23.5	<23.5	0.3	0.65	3.0	0.25	
23.5	23.5	AV-15P	0.3	0.7	3.2	0.3	
24	24	0.3	0.8	3.4	0.3	
24.5	24.5	0.3	0.8	3.8	0.3	
25	25	0.3	0.9	4.0	0.3	
25.5	25.5	0.3	1.0	4.3	0.3	
<26	<26	0.3	1.0	4.4	0.3	
26	26	AV-17P	0.4	1.1	4.5	0.4	
27	26.5	0.4	1.2	5.0	0.4	
28	27	0.5	1.3	5.5	0.4	
29	27.5	0.5	1.5	6.0	0.4	
30	28	0.5	1.6	6.6	0.4	

The specific standard value of the anterior chamber volume is 0.3 ml while the standard posterior chamber volume is 0.7 ml. Since the anterior and posterior chamber spaces must be filled with viscoelastic material, the following equation was derived:

Recommended silicone oil volume = inner ocular chamber volume - recommended anterior chamber viscoelastic material - recommended posterior chamber viscoelastic material - filling FCVB own volume. This equation is the basis for measuring the recommended silicone oil volume (see Table 2).

Inner ocular cavity capacity outcomes in practice based on the contralateral eye

As shown in Supplemental Table 1, we reviewed the postoperative findings of all 253 patients treated with the computerized 3D reconstruction technique used to select the FCVB size and the recommended volume of silicone oil to be injected.

Table 3 shows the FCVB size corresponding to the ocular axis and the volume of silicone oil. There were 11 cases of AV-10P with a 18.55 ± 1.00 mm CT eye axis in the treated eye and 1.05 ± 0.21 ml of silicone oil, 41 cases of AV-12P with a 20.47 ± 0.45 mm CT eye axis in the treated eye and 1.58 ± 0.18 ml of silicone oil, 163 cases of AV-13.5P with a 22.07 ± 0.56 mm CT eye axis in the treated eye and 2.48 ± 0.29 ml of silicone oil, 31 cases of AV-15P with a 24.07 ± 0.68 mm CT eye axis in the treated eye and 3.57 ± 0.39 ml of silicone oil, and 7 cases of AV-17P with a 27.51 ± 1.31 mm CT eye axis in the treated eye and 5.71 ± 0.81 ml of silicone oil. Of all the sizes, the AV-13.5P was the most frequently used, representing 64.43% of the total. Table 3 253 patients with FCVB sizes, volume of silicone oil injected and mean axial values of the treated eyes

Size	Amount	Ratio	Age	CT eye axis of surgical eye(mm)	Volume of silicone oil（mL）	
AV-10P	11	4.35%	34.55±10.86	18.55±1.00	1.05±0.21	
AV-12P	41	16.21%	40.85±14.24	20.47±0.45	1.58±0.18	
AV-13.5P	163	64.43%	42.93±14.47	22.07±0.56	2.48±0.29	
AV-15P	31	12.25%	36.70±12.98	24.07±0.68	3.57±0.39	
AV-17P	7	2.77%	46.43±11.46	27.51±1.31	5.71±0.81	

Clinical outcomes

The 253 cases were from 32 hospitals in china, with the most being Shandong Provincial Hospital, the least being Huaihua First People’s Hospital. There were 216 males and 37 females, and the average age was 42 ± 14 years old, all of whom were successfully implanted with FCVB. All the patients were reviewed postoperatively by a local surgeon and followed up from 6 months to 2 years. There was no significant difference in postoperative visual acuity scores compared with preoperative (P = 0.097) (see Table 4), Postoperative IOP(10.29 ± 0.57mmHg)was slightly higher than preoperative IOP (9.76 ± 0.48 mmHg), but there was still no statistically significant difference between the two comparisons (P = 0.405). Table 4 Preoperative and postoperative visual scores distribution

	Scores	Preoperative Frequency	Postoperative Frequency	
NLP	0	64	66	
LP	1	48	36	
HM	2	49	40	
CF	3	11	9	
>0.05	5	1	1	
	Total	173	152	

The anterior chamber maintains a good depth. The most common complications were mainly anterior chamber hematoma and low IOP. No further severe corneal opacity and drainage valve exposure was seen, no endophthalmitis or sympathetic ophthalmia occurred. None of the patients had FCVB removed. In addition, three typical cases are presented to show the effectiveness of the treatment and safety of the postoperative period. Case 1 was found to have a quiet anterior segment 10 months postoperatively with a deep anterior chamber and a gap of about 2–3 mm between the iris and FCVB-lens surfaces, suggesting an excellent posterior chamber space. The color-fundus photographic examination showed retinal reattachment (as shown in Fig. 5A). Case 2 had corneal clouding edema due to preoperative silicone oil entering the anterior chamber. One and a half years after surgery, the patient was found to have healed corneal clouding with good anterior chamber depth. Due to preoperative ocular atrophy, an overhead prosthetic eyepiece was worn to improve the appearance, leading to a good appearance and normal eye movement, and CT showed a prosthetic eyepiece in front of the eye with a gap between them. Case 3 had bullous keratopathy due to long-term silicone oil filling and retinal scarring in the fundus, and the patient had significant pain. Six months after the implantation of the product, the patient’s cornea became significantly clearer; the anterior chamber was slightly shallow, OCT showed that there was a FCVB capsule about 200 μm thick in front of the scarred retina, and the patient’s pain had disappeared.Fig. 5 Efficacy of FCVB implantation in three cases. A In the 10-month follow-up case of severe retinal detachment, anterior segment examination showed that there was good anterior chamber depth and posterior chamber space, and there was a certain distance between the FCVB lens surfaces and the iris; The color-fundus photographic examination showed retinal reattachment. B The patients with silicone oil eyes and corneal opacity were followed up for one and a half years. Silicone oil was in the anterior chamber before operation, and there was corneal pathological edema and opacity; After treatment, anterior segment OCT showed corneal flattening. After wearing overhead artificial eyepiece, the eye appearance was good. C In patients with bullous keratopathy, it was found that the bullae disappeared, the cornea became transparent, OCT showed that there was a FCVB capsule about 200 μm thick in front of the scarred retina

Discussion

In this study, we reconstructed 3D models of vitreous cavities using a computer 3D reconstruction technique to select appropriate FCVB sizes, which were placed into the vitreous cavities of 253 treated eyes with different degrees of atrophy. This method is of great significance for accurately predicting the FCVB size and volume of silicone oil needed in atrophic eyes in the future.

It is complicated to measure the axial length in severely traumatized eyes in the early post-traumatic period. In addition, as a result of scleral and retinal collapse in traumatized eyes, the axial length cannot truthfully reflect the volume of the vitreous body. Furthermore, neither A-scan nor IOL Master can accurately measure the axial length in silicone-oil-treated eyes [28]. Furthermore, FCVB is designed in five sizes to match differently sized eyes, according to the length of the eye axis. It needs to be slightly distended in the eye but not overdistended, which reduces the flatness of its lens surface and leads to complications.

Therefore, it is extremely difficult to determine the appropriate size of FCVB and the amount of silicone oil needed depending on the axial length of affected eyes. In this study, the anterior-posterior and horizontal diameters of the unaffected contralateral eyes were innovatively used to anchor those of the CT images of both eyes, which were magnified by the same amount to estimate the anterior-posterior and horizontal diameters of the affected eyes. Next, the FCVB size and the volume of silicone oil and anterior- and posterior-chamber viscoelastic agents were calculated using Table 2, which was established using the computer-based 3D reconstruction technique.

This method can be used to predict the prognosis of most patients. The accurate preoperative prediction of FCVB size, silicone oil volume, and anterior- and posterior- chamber viscoelastic agents can shorten the learning curve for surgeons, ensure good postoperative outcomes, and help to evaluate the postoperative outcomes between different surgeons by using much more uniform standards.

The preoperative data from 253 patients (35 females, 13.83%) were included. Table 3 shows that most of the patients received 13.5P (64.43%), while 10P (4.35%) and 17P (2.77%) were the least commonly used. In further studies, we must increase the size of the evaluated sample. Furthermore, although it is easy to measure the axial length in CT images with a ruler, it is necessary to develop relevant software that can automatically predict the FCVB size, silicone oil volume, and anterior- and posterior- chamber viscoelastic agents upon inputting only the axial length of the unaffected eye measured by A-scan ultrasonography and the CT image taken in a horizontal position.

This method can improve the surgical outcomes and minimize the incidence of postoperative complications (such as shallow anterior chamber and corneal whitening). Although there is no significant improvement in postoperative visual acuity and only a slight increase in intraocular pressure compared with before surgery, the main function of FCVB is to preserve the eyeball and avoid eye extraction. As reported previously, the main FCVB complications were a shallow anterior chamber and corneal opacity [18–24]. In the past, when accurate predictions could not be made before operations, the FCVB size and silicone oil volume were determined by surgeons during operations, which could easily lead to the selected FCVB size and the volume of silicone oil injected being too large. In such cases, the lens surface of the second-generation FCVB changes from flat to convex, resulting in the loss of posterior-chamber space and anterior-chamber ischemia due to the squeezed ciliary body, which leads to a shallow anterior chamber and corneal whitening. The 3D reconstruction method can significantly reduce the occurrence of complications because the 3D reconstruction method first fills with viscoelastic to ensure anterior depth and posterior space before considering injection. The amount of silicone oil also does not cause the surgeon to misjudge the injection of too much silicone oil, which leads to ischemia in the anterior segment and shallow anterior and corneal whitening. In this new method, the posterior-chamber space is preserved by occupying the space in advance with a viscoelastic agent, and the anatomical factors of these complications are eliminated. Thus far, the treatment effect has been satisfactory, as shown in Fig. 5. In general, after prolonged filling with silicone oil, the migration of silicone oil into the anterior chamber causes a decrease in the amount of corneal endothelium, corneal-banding degeneration, and even perforation [29, 30]. In cases 2 and 3 described in this paper, due to the FCVB’s restriction of the silicone oil flow into the anterior chamber, the cornea was fed by its own aqueous humor, which was secreted by the ciliary body, resulting in significant improvements in the preoperative corneal lesions. The limitation of this paper is that the postoperative observation time is not long enough. In addition, the vast majority of the patients were manual laborers who could not receive timely follow-up examinations; the large number of hospitals involved also affected the quality of the postoperative patient data collection.

In conclusion, 3D reconstruction prediction is a good solution for eyeballs with obvious individualized changes after trauma, and this method is helpful for guiding doctors to standardize the model selection for patients.

Supplementary Information

Supplementary Material 1.

Acknowledgements

We thank the patients and their families for their continous support of the study, and thank surgeons for providing data. We are also grateful to the doctors who provided postoperative data from the 32 hospitals covered in the article.

Authors’ contributions

H Y performed the research as well as analyzing and interpreting the data; QY G and XF L data curation and investigation; CD L, SW L, Y C, HP S, JG Y, BS L, ZH Y, YX Z and LXY Z performed the surgery; SQ Q, YY L (Vesber Vitreous Institute) and YY W drafted the manuscript; XD M and YY L (Tianjin Medical University General Hospital) revised and edited the article. All authors agreed to the journal to which the article would be submitted, gave final approval of the version to be published, and agreed to be accountable for all aspects of the work. All authors have read and agreed to the published version of the manuscript.

Funding

This study was funded by Scheme of Guangzhou for Leading Talents in Innovation and Entrepreneurship (No: 2020004).

Availability of data and materials

The datasets generated and/or analyzed during the current study are not publicly available but are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study protocol was approved by the Zhongshan Ophthalmic Center, Sun Yat-sen University (Ethical NO.2019KYPJ076), Shenzhen Eye Hospital (NO.2019KYPJ076), Xiamen Eye Center of Xiamen University (NO.IRB2021-YX-049-01), Xi’an People’s Hospital (NO.IRB2021-YX-049-01), Tianjin Medical University General Hospital (NO.IRB2021-YX-049-01), and was conducted in accordance with the Declaration of Helsinki, the International Conference on Harmonisation of Good Clinical Practice guidelines and applicable Chinese law. Informed consent was obtained from all subjects involved in the study.

Consent for publication

Written informed consent for publication of their clinical images was obtained from the patient.

Competing interests

None of the authors has any conflicts of interest to disclose except for authors of Vesber Vitreous Institute. Vesber Vitreous Institute is a research center established by Guangzhou Vesber Biotechnology Co. Ltd. The institute mainly focuses on the research and translation of clinical medical results in ophthalmology, and the authors Qianying Gao, Siqi Qiao, Yingyu Wang and Yuanyuan Liu are all workers from the institute. The authors have no competing interests as defined by BMC, or other interests that might be perceived to influence the results and/or discussion reported in this paper.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Chongde Long and Qianying Gao contributed equally to this work.
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