Consensus on the Treatment of Severe Ocular Trauma and Silicone Oil–Dependent Eyes Using Foldable Capsular Vitreous Body

ABSTRACT

Aim

To establish evidence‐based guidelines for the application of the foldable capsular vitreous body (FCVB) in managing severe ocular trauma and silicone oil–dependent eyes.

Methods

We conducted a comprehensive search across multiple databases, screening, extracting, and evaluating research evidence. Experts in ocular trauma and vitreoretinal surgery provided practical insights and formulated key questions. Using the Delphi method, the working group identified seven clinical issues and established outcome indicators. Seven recommendations were developed, reviewed, and approved by a multinational consensus expert group.

Results

This consensus presents seven evidence‐based recommendations for FCVB implantation, emphasizing the importance of patient assessment, FCVB model selection, and intraoperative and postoperative management. Each recommendation is supported by detailed explanations and evidence, highlighting the potential benefits of FCVB as an alternative to traditional treatments for severe ocular trauma and silicone oil–dependent eyes, including reduced complications and improved visual outcomes.

Conclusions

On the basis of existing literature and expert consensus, this consensus provides evidence‐based guidance for FCVB application in treating severe ocular trauma and silicone oil–dependent eyes. The recommendations serve as a valuable resource for ophthalmologists, facilitating more effective and safer treatment options for patients.

Abbreviations

FCVB

foldable capsular vitreous body

IOL

intraocular lens

IOP

intraocular pressure

PPV

pars plana vitrectomy

TA

triamcinolone acetonide

UBM

ultrasound biomicroscope

1. Introduction

Severe ocular trauma, a complex disorder and leading cause of monocular blindness, can significantly compromise both the structural integrity and functional capacity of the eye, potentially resulting in vision loss [1]. Although silicone oil tamponade is an effective treatment for severe ocular trauma, prolonged use can lead to complications, such as silicone oil emulsification, complicated cataract, secondary glaucoma, and band keratopathy. Some patients may develop silicone oil dependency, requiring repeated silicone oil exchanges, which imposes significant physical and financial burdens [2, 3]. In cases of severe eye injuries where the eyeball is difficult to repair or impossible to fill with silicone oil, eyeball atrophy and enucleation may occur. Severe ocular trauma is the primary risk factor for enucleation [4]. Enucleation poses not only psychological challenges to patients but also considerable burdens to nations, to society, and to families. The foldable capsular vitreous body (FCVB), developed in 2017, is an innovative product designed to preserve the eyeball, prevent enucleation, and promote psychological resilience while reducing the economic burden on patients and healthcare systems. Although FCVB is widely used internationally, there is a need for standardization regarding indications, preoperative preparation, surgical techniques, and complication management; hence this consensus.

2. Methods

2.1. FCVB

FCVB is the first innovative product that mimics the natural vitreous body by encapsulating the implanted silicone oil, preventing its direct contact with ocular tissues. It consists of a capsule, a drainage tube, a drainage valve, and a fixation loop. The capsule is modeled after the human eye's vitreous cavity through computer simulation, and it features a specially designed lens surface. It is made from a medical‐grade silicone polymer [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26].

During surgery, the capsule is folded and implanted into the vitreous cavity. A compatible 25G silicone oil injection needle is used to inject silicone oil through the drainage valve. The capsule is then double‐looped and fixed within the eye with the fixation loop and drainage tube using sutures, preventing the silicone oil from damaging the ciliary body (Figure 1 and Video S1). This product helps maintain the posterior chamber space, allowing the ciliary body to gradually restore its function without affecting its aqueous humor secretion capabilities, thereby sustaining intraocular pressure (IOP). It also prevents silicone oil emulsification and displacement while providing comprehensive support for the retina and maintaining the shape of the eyeball [27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46].

FIGURE 1.

Schematic of FCVB implantation process.[1] Dissect the conjunctiva at the 10:30 and 4:30 positions. Using a 1 mL syringe, guide the long needle of the 9‐0 polypropylene intraocular lens fixation suture to exit 4 mm posterior to the corneoscleral limbus at the 4:30 position, after inserting it 5 mm behind the limbus.[2] Create a scleral tunnel incision 2 mm posterior to the corneoscleral limbus between the 9 and 12 o'clock positions, depending on the product model. Pull out the 9‐0 polypropylene intraocular lens fixation suture through the incision and cut it centrally.[3] Tie and fix the loop at the 4:30 position using the suture. Using intraocular lens platform forceps, insert the capsule into the vitreous cavity through the limbal incision, ensuring the fixation loop faces upward. After half of the product is inserted, cut the ligature. Inject the specified silicone oil through the drainage valve.[4] Secure the drainage tube with the 9‐0 polypropylene intraocular lens fixation suture at the 10:30 position.[5] Implant the drainage tube and drainage valve into the eye, positioning the drainage valve near the edge of the capsule at the 9 o'clock position.

2.2. Origination, Development, and Support Units

Tianjin Medical University General Hospital conducted data collection, collation, and clinical validation for this consensus.

2.3. Consensus Users and Target Groups

This consensus is intended for all medical institutions utilizing FCVB to treat severe ocular trauma and silicone oil–dependent eyes. The primary users are ophthalmologists, and the target population comprises patients diagnosed with severe ocular trauma and silicone oil dependency.

2.4. Steering Group for Consensus Development

The consensus development working group includes the editorial committee, consensus expert group, consensus development group, and audit expert group. The editorial committee and consensus expert group comprise 36 experts from 4 disciplines/specialties across 6 countries, along with patient representatives and legal advisors.

2.5. Clinical Problem Selection

The research group systematically searched for consensus documents, systematic reviews, and original studies related to FCVB use in treating severe ocular trauma and silicone oil–dependent eyes. On the basis of the search results and in‐depth interviews with stakeholders, the group compiled a list of clinical questions and outcome indicators. Fifty ophthalmologists participated in a questionnaire survey, and using the Delphi method, seven clinical problems were identified. Clinical experts and scientists formulated these clinical problems based on the population, intervention, comparison, and outcome framework. A list of outcome indicators was proposed on the basis of the literature search results, in‐depth interviews, and patients’ wishes and values. The consensus development working group finalized the outcome indicators in relation to the consensus after several rounds of discussion.

2.6. Evidence Collection

We searched multiple databases, including PubMed, Embase, The Cochrane Library, and Web of Science for English articles, and CNKI, CBM, Wan Fang Data, and VIP databases for Chinese articles. The search period extended from database inception to October 2024. The websites that publish clinical guidelines and consensus include the National Guideline Library, International Guideline Collaboration Network, Inter‐School Guideline Network in Scotland, National Institute for Clinical Excellence, and WHO. The retrieval period was from the date of database inception to October 2024. The references of the included literature were thoroughly examined.

2.7. Evidence Screening and Extraction

Research evidence included clinical guidelines, systematic reviews, randomized controlled trials, cohort studies, case–control studies, and cross‐sectional studies on FCVB use in treating severe ocular trauma and silicone oil–dependent eyes. Two professionals independently screened and extracted information, with a third party consulted for disagreements.

2.8. Evaluation and Assessment of the Quality of Evidence

We used AMSTAR‐2 [47] to evaluate the methodological quality of systematic reviews, the Cochrane bias risk assessment tool for clinical trials, QUADAS‐2, and the Newcastle–Ottawa scale (NOS). Two professionals independently screened and extracted information from each work, and a third party was consulted for any differences in opinions [48, 49].

GRADE [50, 51] was employed to assess evidence quality and recommendation strength. A good practice statement (GPS) was used to evaluate the relevant qualitative research [52].

2.9. Patient Preferences and Values

The consensus development working group created a questionnaire to evaluate patient preferences and values, involving 100 patients with severe ocular trauma or silicone oil‐dependent eyes. The findings were analyzed statistically, collated by the members of the consensus development group, and served as bases in the formulation of recommendations.

2.10. Development and Updating of Recommendations

The working group formulated seven recommendations based on meta‐analysis results, patient values, intervention costs, and benefit–risk balance. Consensus was reached using a one‐round Delphi questionnaire.

2.11. Audit and Approval

The draft consensus was reviewed by an audit expert group comprising ophthalmology experts, consensus methodology experts, legal advisors, and patient representatives. The working group revised the document based on feedback, and the consensus expert group approved the final version.

2.12. Dissemination and Implementation of the Consensus

Upon release, the consensus will be disseminated through academic conferences, journal publications, and online platforms. Periodic studies will be conducted over the next 2 years to evaluate the treatment status of mechanical ocular trauma.

3. Results

3.1. Clinical Recommendation 1

3.1.1. Indications and Contraindications for FCVB

FCVB is primarily recommended for patients with severe retinal detachment following ocular trauma, especially when conventional vitreous substitutes are ineffective. It is also indicated for patients who have undergone multiple retinal detachment surgeries, including silicone oil tamponade, and those with recurrent detachment after silicone oil removal. However, FCVB implantation is contraindicated in patients with uncontrolled intraocular inflammation or conditions such as proliferative diabetic retinopathy [34, 35, 36, 37, 38, 39, 40, 41, 42].

3.1.2. Recommendation Explanations

The eligible patient cohort must meet the following criteria:

1. age >18 years (patients <18 years with silicone oil–dependent eyes and at risk of eyeball atrophy may be included with parental consent);

2. visual acuity <0.05 in the affected eye;

3. axial length >16 mm in the affected eye;

4. severe retinal detachment unresponsive to conventional vitreous substitute therapies due to:

   1. severe unilateral ocular perforating or penetrating injuries;
   2. retinal or choroidal defects from severe unilateral ocular rupture injuries;
   3. untreatable giant posterior scleral rupture injuries;
   4. long‐term silicone oil retention with incomplete retinal reattachment;
   5. multiple retinal detachment surgeries with silicone oil tamponade and recurrent detachment after oil removal;

5. silicone oil–dependent eyes with complications preventing oil removal;

6. eye globe atrophy due to silicone oil tamponade or after oil removal;

7. eyes with attached retinas following retinal surgery after gas absorption or oil removal, or with oil promoting phthisis due to persistent inflammation causing ciliary body shutdown.

3.1.3. Contraindicated Patient Cohort

The following conditions render individuals ineligible:

(1) confirmed silicone allergy or scar constitution; (2) endophthalmitis; (3) uveitis, sympathetic ophthalmia; (4) proliferative diabetic retinopathy; (5) unmanageable concomitant ocular comorbidities; (6) severe systemic diseases; (7) pregnancy, planned pregnancy, or lactation; (8) history of substance abuse or alcohol dependence [27, 28].

Because retrobulbar anesthesia or general anesthesia is required during FCVB surgery, and postoperative oral anti‐inflammatory drugs and corticosteroids are necessary, there are specific requirements for patients’ systemic and ocular conditions. Systemically, patients must be able to tolerate the procedure, while locally, the eye must be free from infection prior to FCVB surgery, as existing infections could otherwise lead to exacerbation. For pregnant women, whether undergoing retrobulbar or general anesthesia for FCVB surgery, the anesthesia itself carries potential risks to the fetus.

3.2. Clinical Recommendation 2

3.2.1. FCVB Model Selection and Silicone Oil Injection Volume Calculation

A thorough preoperative ophthalmic assessment is essential before FCVB implantation. The anterior–posterior and horizontal diameters of the affected eye should be accurately determined using data from the contralateral eye's IOLMaster and three‐dimensional orbital CT reconstruction of both eyes. The appropriate FCVB model and silicone oil injection volume can be determined using Table 1 [44].

TABLE 1.

Recommended form for foldable capsular vitreous body (FCVB) model selection and silicone oil injection volume.

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

3.2.2. Recommendation Explanations

Preoperative ophthalmic examinations should include the following:

(1) facial photography; (2) visual acuity assessment; (3) IOP measurement; (4) refractive error evaluation; (5) axial length measurement (IOLMaster/A‐scan); (6) anterior segment imaging; (7) fundus examination; (8) ocular B‐scan ultrasonography; (9) ultrasound biomicroscope (UBM); (10) corneal endothelial cell count; (11) orbital CT scan.

The anterior–posterior diameter refers to the distance from the anterior vertex of the cornea to the posterior vertex of the sclera in the maximum cross‐sectional image of the eye on a horizontal CT scan. The horizontal diameter refers to the longest distance between the outer layers of the sclera in the maximum cross‐sectional image of the eye on a horizontal CT scan (Figure 2). These parameters guide FCVB model selection, silicone oil injection volume, and viscoelastic agent dosages (Table 1) [44]. Ciliary body function should also be evaluated, as it significantly impacts implantation success. Evaluation parameters include UBM, IOP, axial length, anterior chamber depth, and corneal endothelial cell count (Table 2).

FIGURE 2.

Schematic of the anterior–posterior and horizontal diameter measurement. The anterior–posterior diameter refers to the distance from the anterior vertex of the cornea to the posterior vertex of the sclera in the maximum cross‐sectional image of the eye on a horizontal CT scan. The horizontal diameter refers to the longest distance between the outer layers of the sclera in the maximum cross‐sectional image of the eye on a horizontal CT scan.

TABLE 2.

Ciliary body structure and function scoring system.

Ciliary body	Intraocular pressure (mmHg)	Ocular axial length change (compared with the contralateral eye)	Anterior chamber depth	Corneal endothelial cell count	Ciliary body membrane onset	Points
Intact	10–21	None	>2 corneal thickness (CT)	>2000	None	3
Detachment	5–10	1 mm	1–2 CT	1000–2000	<50%	2
Atrophy	1–5	2 mm	<1 CT	500–1000	>50%	1
Absence	<1	>2 mm	Adherent to cornea	<500	Complete involvement	0

3.3. Clinical Recommendation 3

3.3.1. Suitability Assessment of Ciliary Body Function for FCVB Implantation

Prior to FCVB implantation, patients’ ciliary body function must be evaluated using multiple parameters, including UBM, IOP, ocular axial length changes, anterior chamber depth, and corneal endothelial cell count. The retina and other ocular structures should also be assessed to determine FCVB suitability (Tables 2 and 3).

TABLE 3.

Foldable capsular vitreous body (FCVB) implantation suitability based on ciliary body function score and retinal/choroidal/iris condition.

Classification	Description	Suitability for FCVB
Type A	Good ciliary body function (score above 10) + more than 3/4 of the retina is intact	No
Type B	Good ciliary body function (score above 10) + less than 3/4 of the retina is intact or a choroidal defect is noted	Yes
Type C	Good ciliary body function (score above 10) + aniridia; silicone oil dependency is expected to arise	Yes
Type D	Poor ciliary body function (Scores 5–10)	Yes
Type E	Ciliary body failure (Score <5 or silicone oil is present in the anterior chamber)	Yes, but with limited efficacy

3.3.2. Recommendation Explanation

The ciliary body structure and function are evaluated on the basis of several parameters (Table 2).

It is particularly emphasized that normal IOP under silicone oil does not indicate normal ciliary body function. At this time, the IOP represents a dynamic equilibrium at a low level between aqueous humor production and outflow. The degree of axial shrinkage is significantly less than the degree of shrinkage in the inner ocular cavity volume. For example, when the axial length is 23.5 mm, the inner ocular cavity volume is 4.5 mL; when the axial length shrinks to 21.5 mm, the inner ocular cavity volume reduces to 3.4 mL; and when the axial length shrinks to 20.5 mm, the inner ocular cavity volume further reduces to 2.7 mL (the inner ocular cavity volume can be calculated from Table 1, where for an axial length of 23.5 mm, the intraocular volume = 0.3 mL recommended volume of the anterior chamber viscoelastic agent + 0.7 mL recommended volume of the posterior chamber viscoelastic agent + 3.2 mL recommended volume of the silicone oil + 0.3 mL the capsule self‐volume). When silicone oil is present in the anterior chamber, it causes a reduction in corneal endothelial cell count. However, under silicone oil, the corneal endothelial count cannot be measured and appears in a pseudo‐transparent state. Therefore, the corneal endothelial count should be measured again 2–4 weeks postoperatively. As the duration of silicone oil filling in the eye increases, ciliary body function progressively declines. The best surgical outcomes are achieved when the silicone oil is removed and the FCVB is implanted 1–2 months after silicone oil filling.

3.4. Clinical Recommendation 4

3.4.1. Preoperative Preparation and Doctor–Patient Communication for FCVB Implantation Surgery

Preoperative preparations should include surgical instrument setup, team training, practice sessions, manual review, and preparation of prophylactic medications. Adequate communication regarding intraoperative risks and potential complications can improve surgical success rates and patient satisfaction [34, 35, 36, 37, 38, 39, 40, 41, 42].

3.4.2. Recommendation Explanation

1. preoperative instrument preparation:

   1. routine pars plana vitrectomy (PPV) equipment;
   2. FCVB (with a spare unit of the same model);
   3. silicone oil or heavy silicone oil (viscosity ≥5000 cst);
   4. intraocular lens (IOL) platform tweezers;
   5. short (3 mm) blunt 25G silicone oil injection needle;
   6. 9‐0 polypropylene IOL loop fixation sutures;
   7. 5‐0 external retinal detachment sutures;
   8. 1 and 5 mL syringes;
   9. sterile gauze;
   10. beakers;
   11. sterile gloves.

2. surgical team training on FCVB implantation. They should be able to identify the lens surface of the capsule, the mold line, the front and back of the drainage valve, and the fixation loop;

3. at least one preoperative practice session using a model;

4. thorough review of the instruction manual;

5. administration of local anti‐inflammatory or hemostatic medications as needed;

6. corneal diameter measurement and facial photography for pre–post comparison;

7. attention to the healthy eye's visual function in cases of severe trauma.

Precautions for doctor–patient communication before surgery: Patients may experience anxiety, depression, irritability, and other adverse emotions before, during, and after FCVB implantation surgery, which can lead to respiratory distress and hypertension, among other conditions. This phenomenon not only has a significant impact on the circulatory and neuroendocrine systems but also directly affects patients’ subjective experiences, postoperative recovery, and surgical outcomes. In addition, patients inevitably experience anxiety due to the high cost of surgery and limited postoperative visual recovery. Adequate communication with patients is essential, during which the key points of preoperative and postoperative care must be presented, the FCVB surgical procedure must be explained, and the potential postoperative complications must be discussed. In particular, doctors must emphasize that surgical outcomes are closely related to patients’ ciliary body function, and poor outcomes may be observed in patients with ciliary body failure. Before surgery, patients should be fully informed of the risks of postoperative corneal whitening, anterior chamber shallowing, and the need for reinjection of viscoelastic agents. Gaining a correct understanding and having a reasonable expectation of surgical outcomes would be helpful to patients. Rational and voluntary acceptance of surgery will greatly contribute to improving the surgical success rates and postoperative patient satisfaction.

3.5. Clinical Recommendation 5

3.5.1. Surgical Procedure and Precautions for FCVB Implantation

Surgeons should rinse sterile, dust‐free gloves thoroughly before handling FCVB to prevent contamination. Capsular integrity should be tested in sterile saline, and debris contamination should be avoided during folding. Existing scleral encircling buckles should be removed, and residual vitreous and ciliary membranes should be maximally removed. Sharp instruments should be avoided during FCVB implantation, and proper positioning is crucial [35, 36, 37, 38, 39, 40, 41, 42].

3.5.2. Recommendation Explanation

1. The sutures of the scleral wound should be firm and, when necessary, must be reinforced with non‐absorbable stitches, especially 2 weeks after the patients received primary suture for a relatively long corneal scleral laceration.

2. A larger incision should be made in advance at the 4 or 8 o'clock position of the peripheral iris with an anterior chamber puncture. Implantation of IOL is not recommended.

3. During PPV, intravitreal injection of triamcinolone acetonide (TA) helps to trace the vitreous and inhibits inflammation and hemostasis.

4. Surgeons may try to remove the residual ciliary membrane and vitreous and loosen the retina to achieve better reattachment. Laser photocoagulation is performed after the gas–liquid exchange.

5. The capsule integrity of FCVB should be determined before implantation (the sterile gloves should be rinsed before operation to avoid the dusting powder found on the glove surface from contaminating the FCVB and from entering the globe). Any contact between sharp instruments (including non‐toothed micro forceps) and the capsule and drain tube must be avoided throughout the surgical procedure.

6. The air in the capsule must be evacuated until the capsule becomes vacuumed, and the arc must be maintained and should not be flipped. The drain tube is found at the highest point of the arc with the fixation loop and lens facing up; the FCVB is folded in half from bottom to top and then rolled as slender as possible from bottom to top. The 5‐0 external‐route suture is used to bind the FCVB slightly behind the center of the capsule.

7. The conjunctiva is dissected from the Tenon's capsule at the 10:30 and 4:30 positions. A long needle of 9‐0 double‐armed polypropylene suture is to be inserted 5 mm behind the limbus at the 10:30 position, then a 1 mL syringe introduces a long needle (4 mm) behind the limbus at the 4:30 position.

8. There are two approaches for FCVB implantation: (1) A scleral tunnel limbal incision is made 2 mm away from the limbus between the 9 and 12 o'clock positions according to the product model, through which the double‐armed polypropylene suture is pulled out and cut in half. The suture is ligated at 4:30 to fix the loop, and the intraocular suture is pulled out slightly to avoid entanglement with the FCVB. At the 10:30 position, the suture must be managed properly to prevent it from entering the eye during FCVB implantation. The FCVB is implanted into the vitreous cavity through the limbal incision with IOL forceps, and the loop is kept facing upward [45]. The tying suture can be cut off once half of the FCVB has been inserted, and then the recommended volume of silicone oil is slowly injected into the capsule through the drainage valve. (2) The pneumatic or hydraulic pressure of the vitrectomy instrument is maintained at approximately 50 mmHg. A 45° incision in the sclera 5.0 mm posterior to the temporal limbus is made using a 15° stab knife, the length of which should be 3.5–4.5 mm (as indicated in the product label) and shaped like an “L.” The center of the incision should be located at the 10:30 position. The internal incision should be turned over and inspected to ensure patency. In the case of ciliary body detachment and bleeding during the implantation process, the scleral incision should be dissected thoroughly with micro scissors.

9. Before injection of the silicone oil into the capsule, the air in the silicone oil should be evacuated, and the original volume of silicone oil must be recorded. The cup of the valve is preinjected using a 1 mL syringe needle, then the 25G silicone oil needle is punctured into the drainage valve cup after passing through the drainage valve; the needle should not be stabbed into the drainage tube. A vitrectomy machine can help inject the specified silicone oil to avoid subjective overbalance. The drainage valve can be held vertically with toothed micro forceps [30, 39, 44].

10. The infusion tube used in PPV operation should be withdrawn in time to prevent stabbing the capsule.

11. Flushing irrigation blunt‐end needle can be inserted from the drainage valve and through the drainage tube, reaching the edge of the large bubble in the capsule to suck out the excess gas, which cannot be pumped with a syringe. The drainage tube is ligated with the 9‐0 double‐armed polypropylene suture left at 10:30, and then the drainage tube and valve are implanted in the globe, with the drainage valve located close to the edge of the capsule at 9 o'clock.

12. The scleral tunnel incision is sutured with a 10‐0 non‐absorbable suture, and the anterior chamber and posterior chamber are reconstructed with a specified viscoelastic agent. The IOP evaluated through scleral measurement is usually around 15 mmHg, which is slightly lower than that measured in silicone oil tamponade alone (but it should be noted that the eyelid speculum also has a certain impact on IOP). Injecting an excessive amount of silicone oil must be avoided, as this may lead to anterior segment ischemia. The amount of injected silicone oil should be recorded, and scleral and corneal pressure should be distinguished from each other, with scleral pressure being the standard [28]. When IOP is relatively low after the specified amounts of silicone oil and viscoelastic agent are injected, additional viscoelastic agent can be administered to achieve the ideal IOP. It is crucial not to achieve the desired IOP by over‐injecting silicone oil, as this would cause the silicone oil to encroach upon the posterior chamber space, leading to anterior segment ischemia and corneal opacity. For an eyeball with an axial length of 23.5 mm, the recommended volume of silicone oil within the FCVB is 1 mL less than that for common silicone oil tamponade.

13. A parting line (molding seam) detected through the pupil indicates that the lens surface of the FCVB is not flat, suggesting that the lens surface is tilted and thus requires adjustment toward the opposite direction using an iris repositor.

14. The fixation suture should be embedded at the 10:30 and 4:30 positions at the intrascleral layer in the “z” style.

15. The blunt illumination probe in the anterior chamber can assist in observing the postoperative situation (expansion of the capsule, presence of bubbles in the capsule, retinal reattachment, and blood supply).

16. The conjunctiva is sutured with 8‐0 absorbable sutures.

17. At the end of the operation, peribulbar injection of 10 mg TA and subconjunctival injection of dexamethasone are performed.

18. A pressure bandage is applied to the surgical eye to immobilize the eyeball and prevent bleeding.

19. The existing IOL may not be removed given that the FCVB may be implanted through the scleral incision 5 mm away from the limbus.

20. Selecting the model of FCVB with a specific amount of silicon oil is crucial, as replenishing the silicone oil would be difficult once the drainage valve has been inserted into the vitreous cavity. Considering the potential change in the volume of the vitreous cavity, it is recommended that the drainage valve be implanted through a scleral incision 5 mm away from the limbus, with the valve embedded under the conjunctiva to facilitate silicone oil replenishment in the future (Figure 3).

FIGURE 3.

Schematic of the drainage valve implanted inside (A) or outside (B) the eye.

3.6. Clinical Recommendation 6

3.6.1. Postoperative Precautions for FCVB Implantation Surgery

Patients should maintain a prone position postoperatively. Antibiotics, corticosteroids, and other medications may be administered on the basis of the patient's condition. Strenuous exercise should be avoided, and close follow‐up is recommended. Viscoelastic agents should be replenished immediately if hypotony occurs.

3.6.2. Recommendations Explanation

1. Patients should remain in the prone position for at least 1 week and in the prone or lateral position for 3 months before taking the regular position.

2. Postoperative medications:

   1. General medications: Depending on the patient's condition, antibiotics and corticosteroids may be administered, but caution must be exercised for patients with systemic diseases and for children, for whom intense eye drops must be used instead.
   2. Local medication: One additional dose of peribulbar injection of 10 mg TA may be administered depending on the degree of postoperative inflammation.
   3. Local medication: Tobramycin and dexamethasone ophthalmic ointment (TobraDex, Alcon) (for 2 months but may be adjusted according to eye conditions).

3. Cycloplegics: Atropine eye ointment for half a month, followed by tropicamide eye drops for 1 month.

4. The duration of local treatment should be extended to 3–4 months for patients with severe ocular trauma and for children [38, 45, 46].

5. When hypotony, shallow anterior chamber, or exudative membrane occurs 1–3 months post operation, the viscoelastic agent in the anterior and posterior chambers must be supplemented with 10 mg TA through peribulbar injection. When any of the above situations recurs, repeated treatment (up to two rounds) would be necessary, which is beneficial for slow functional restoration of the ciliary body. It is particularly emphasized that the function of the ciliary body can only be restored under conditions of normal IOP [53]. The purpose of supplementing viscoelastic agents is twofold: on one hand, to restore normal IOP and reduce inflammatory responses; on the other hand, to facilitate the gradual recovery of ciliary body function.

6. Patients are instructed to follow up closely, and complications should be communicated to doctors for timely treatment, or there is a risk of eye atrophy and corneal opacity. The recommended follow‐up visits are as follows: 1, 2, 4, and 8 weeks; 3, 6, and 12 months; and then once a year [29] (see Table 4).

7. Strenuous exercises or excessive uses of eyes are not suggested.

8. When the silicone oil in the anterior chamber impacts corneal endothelial counting prior to surgery, counting must be done when the cornea turns transparent, that is, about 2–4 weeks post‐surgery, allowing for the evaluation of the patients’ postoperative corneal prognosis.

9. For atrophic eyeballs with FCVB implantation, customized hollowed‐out back ocular prostheses may be used if patients have cosmetic requirements.

TABLE 4.

Eye examinations.

Items	Prior to operation	Post operation
		1W	2W	4W	12W	24W	1Y
VA	√	√	√	√	√	√	√
IOP	√	√	√	√	√	√	√
Anterior segment photograph	√			√	√	√	√
Fundus photography	√			√	√	√	√
OCT	√			√	√	√	√
B ultrasound	√					√	√
UBM	√					√	√
Facial photograph	√					√	√
Corneal endothelial counting	√			√		√	√
CT	√						√

Note: After the annual review, each inspection results in the same as the first year of inspection.

Abbreviations: CT, corneal thickness; IOP, intraocular pressure; OCT: Optical coherence tomography; UBM, ultrasound biomicroscope; VA: visual acuity.

3.7. Clinical Recommendation 7

3.7.1. Postoperative Complications and Treatment of FCVB Implantation

Postoperative complications may include intraocular hemorrhage, high or low IOP, and inflammatory reactions, which require timely treatment. Most complications result from pre‐existing trauma or multiple silicone oil tamponade procedures. Surgeons should assess complication risks and set reasonable patient expectations.

3.7.2. Recommendation Explanations

Postoperative complications include the following:

(1) intraocular hemorrhage; (2) high IOP; (3) low IOP; (4) shallow anterior chamber; (5) pupillary fibrous membrane; (6) corneal opacity; (7) FCVB or drainage tube rupture; (8) iris neovascularization.

The treatments of these complications are as follows:

1. Postoperative hemorrhage: This condition is mainly caused by the restoration of intraocular structures after trauma and by surgical incision. Hemostatic agents should be given after surgery. Anterior chamber irrigation is performed for massive bleeding, and if necessary, the scleral incision is loosened to flush the posterior chamber. If IOP is high, IOP‐lowering medications should be administered. Surgeons should evaluate for ciliary body detachment before surgery; in the case of detachment, it must be sutured and re‐attached [21].

2. Postoperative shallow anterior chamber, corneal opacity, corneal banding degeneration, and iris neovascularization: Inappropriate selection of FCVB model, excessive silicone oil tamponade, and aseptic inflammation of the patient should be excluded. The anterior and posterior chambers may be filled with viscoelastic agent. Nutritional corneal epithelial drugs may be used after surgery. If a shallow anterior chamber recurred within 3 months after surgery, viscoelastic agent may be injected into the anterior chamber again.

3. Intraocular infection: Anti‐infective treatment should be given immediately, and FCVB should be removed if the patient is allergic to silicone polymer [21, 30, 33, 36, 37, 38, 39, 45, 46].

4. FCVB drainage valve and drainage tube exposure and FCVB rupture: These conditions require FCVB replacement.

5. Patients with foreign body sensation and pain: This phenomenon is normal, and it generally disappears within 1–2 days post‐surgery.

Ethics Statement

The protocol for the research project has been approved by the Ethics Committee and conforms to the provisions of the Declaration of Helsinki.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Video S1: The Video of FCVB implantation process.