Microsurgical Vitrectomy with Pars Plana Incision for the Removal of Posterior Segment Intraocular Foreign Bodies

This study describes a pars plana incision surgical technique combined with 23 or 25-gauge vitrectomy in the management of intraocular foreign bodies (IOFBs) and to assess its anatomical and functional results. Sixteen patients with ocular trauma complicated with IOFB were enrolled in our study. The mean preoperative visual acuity was 2.01 ± 0.55 LogMAR, and the mean postoperative visual acuity at the final visit was improved to 0.91 ± 0.58 LogMAR (p < 0.001). Until the last follow-up, all IOFBs were successfully removed and anatomic success was obtained. Complications, such as endophthalmitis, silicone oil-dependent, and ocular hypotonia, were not observed. Microsurgical vitrectomy with modified pars plana incision is a safe and effective procedure in the treatment of retained IOFB, especially associated with transparent lens and posterior segment injury.


Introduction
Ocular trauma often leads to severe vision loss and is an important public health problem [1,2].Ocular trauma with retained intraocular foreign body (IOFB) is the main cause of ocular morbidity and blindness in the working-age population [3][4][5].Studies have reported that an IOFB may be present in 18% to 41% of cases of penetrating injuries of the globe [6,7].Ocular trauma caused by IOFB is often accompanied by penetrating injury of corneal or sclera, hyphema, traumatic cataract, vitreous haemorrhage, retinal tear or detachment, and even endophthalmitis [8].In addition to initial damage, secondary injury-caused ocular complications during the foreign body removal process can lead to poor vision outcomes [9].Several techniques or methods for IOFB removal have been reported by diferent investigators [10][11][12][13][14][15][16].At present, there is no unifed standard for surgical methods of foreign body removal.Among patients with diferent entrance and characteristics of posterior segment IOFB, choosing a suitable incision and pathway to remove the IOFB poses a unique surgical challenge to the ophthalmologist.
To explore the safety and efectiveness of modifed pars plana incision in patients with retained IOFBs, here we report a series of cases treated by 23 or 25-gauge pars plana vitrectomy (PPV) in order to assess its anatomical and functional results.

Study Design and Subjects.
In this retrospective case series study, 16 eyes from 16 patients who adopted 23 or 25-G PPV with modifed pars plana incision for the removal of IOFB in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China, between January 2019 and January 2022 were enrolled in the study group.Te principles of this study are consistent with the Declaration of Helsinki and were approved by the Union Hospital's local ethics committee (No. 0153).

Examination Protocol.
A thorough medical history was taken in all cases.Best-corrected visual acuity (BCVA), slitlamp inspection of anterior segment, and posterior segment observation by indirect ophthalmoscopy were performed to assess the eye injuries.Auxiliary examinations, such as computed tomography (CT), were used to evaluate the localisation of the IOFB and assess the state of ocular trauma.All cases underwent 23 or 25-gauge PPV by the same surgeon.According to the clinical manifestation, lens extraction (lensectomy or phacoemulsifcation), intraocular lens (IOL) implantation, retinal repair, and other treatments were performed.Follow-up assessments were performed at 1, 3, and 6 months.Patients with incomplete data or less than 6 months of follow-up were excluded.

Surgical Procedures.
All patients had primary wound repair or self-sealed wounds.Subsequently, a standard 23 or 25 gauge three-port vitrectomy was performed, using the vitrector with a cut rate of 5000/min (Constellation Surgical Vitrectomy System, Alcon Inc., USA).Te operations were performed under retrobulbar anaesthesia, with phacoemulsifcation if necessary.In white cataracts, the anterior capsule was stained with 0.1% indocyanine green for a better view.Using a 6 mm long infusion cannula was considered when choroid detachment was present.All patients were treated with preservative-free triamcinolone acetonide (TA) to help complete posterior vitreous detachment (PVD) and ensure more thorough vitreous removal.
Core vitrectomy was performed before the foreign body was identifed.If a foreign body is found embedded in the retina, 2-3 rows of retinal barrier laser were performed around it.With 20 gauge forceps or with the help of magnet, the IOFB was grasped along its longest axis and removed through the modifed midline pars plana sclera incision (parallel to and 3.5-4 mm behind the limbus at 12 o`clock, which can preserve trocar position for continued vitrectomy) (details shown in the supplementary surgical video https://video.weibo.com/show?fd=1034:4915925892399132).For large and nonmagnetic foreign bodies, perfuorocarbon fuids may be used to protect the macula.Te periphery retina was carefully evaluated at the end of surgery.A long-term intraocular tamponade may be considered if necessary.Antibiotics and steroid eye drops were administered routinely for 4 weeks with gradual tapering after surgery.

Main Outcome Measures.
Te main results were recorded and analysed including age, sex, laterality, characteristics of IOFB (size, location, and chemical nature), the time interval between injury and removal of IOFB, correlated ocular lesions, parameters related to treatment (BCVA and intraocular pressure), and complications.We considered the complete retina attachment until the last follow-up as anatomical success, the improvement in postoperative visual acuity as a parameter of functional success, and the presence of retinal detachment, ocular hypotonia, and/or endophthalmitis as complications.

Statistical Analyses.
For statistical analysis, all numerical data are described either as mean ± standard deviation or as median (minimum-maximum).Te categorical data are recorded as the number and percentage (n, %).Te T-test was used for variable comparison.Visual acuity was converted into LogMAR units using an international standard.Nonnumerical vision counting fngers (CF), hand motion (HM), light perception (LP), and nonlight perception (NLP) were converted to LogMAR values of 1.9, 2.3, 2.7, and 3.0, respectively [17].A p value less than 0.05 was considered as statistically signifcant.

Demographical Results
. Sixteen eyes from 16 patients were included in the study (shown in Table 1).All patients were men.Te left eye was afected in 9/16 (56.3%) of cases.Te average age was 42.1 ± 10.3 years (range, 26 to 56 years) and they were followed for 18 ± 6.9 (min: 10, max: 32, median: 18) months.All injuries to the patients were related to work accidents.None of the patients wore protective glasses at the time of injury.Te interval between the injury and the removal surgery of IOFB was 6.6 ± 6.9 days (time range: 1-30 d).

Preoperative Accompanying Diseases.
Preoperative accompanying diseases included traumatic cataract with capsular rupture in 6 (37.5%) patients, vitreous haemorrhage in 13 (81.3%)patients, retinal detachment in 9 (56.3%)patients, and endophthalmitis in 0 (0%) cases.Te IOFB entrance wound site at cornea in 7 eyes (43.8%), sclera in 6 eyes (37.5%), and limbus in 3 eyes (18.7%).Except for two patients who self-sealed, the remaining 14 (87.5%)patients received primary wound closure prior to IOFB removal surgery. 2 summarises the general data related to the surgical procedures of the entire study population.As intraocular tamponade, nine (56.3%) patients had silicone oil tamponade and all of them completed the silicone oil extraction successfully for a mean of 5.3 months (ranging from 3 to 9 months), while the remaining seven (43.7%) patients did not need any tamping throughout the follow-up period.Among all patients, two aphakic (one had intraocular lens dislocation into the vitreous) cases (18.2%) underwent intraocular lens suspension combined with vitrectomy and IOFB resection.Te remaining 14 cases were phakic eyes at the time of injury and 6 of them had traumatic cataract with lens capsular rupture.Tese six patients (37.5%) underwent lensectomy at the same time as PPV.Tey did not implant the IOL during the frst surgery, in order to calculate the IOL power more accurately once the condition of the eye improved and stabilized.Four of them underwent secondary intraocular lens implantation (three suspension and one sulcus implantation).Among the eight remaining transparent lens patients, seven (43.7%) of them did not need cataract surgery until the last review.Te other one underwent

Discussion
Intraocular foreign bodies are common in work-related trauma, and 66% of IOFB injuries occur between 21 and 40 years of age [11].As reported in other studies, most of our patients were young men of productive age, with impairments primarily related to occupational activities [18].None of the patients in our study wore any form of eye protection, which also highlights the need for prevention education.Traumatic eye injuries associated with IOFB may cause devastating tissue destruction and severe vision loss.Te prognosis varies greatly depending on a series of factors, including preoperative status (initial visual acuity, preoperative retinal detachment, vitreous haemorrhage, and endophthalmitis), degree of injury (nature of IOFB, wound entrance, and location of IOFB), ensuing complications, and especially surgical management (duration between injury and IOFB removal and selection of surgical incision and method) [19].Te objective of IOFB management is to restore the integrity of the eyeball and maximise visual function.Due to its ability to provide direct observation and controlled surgical procedures, PPV is currently the primary surgical method for removing posterior segment IOFBs.In recent years, with the development of minimally invasive vitreoretinal surgical instruments and techniques, microsurgical vitrectomy provides higher cutting efciency and more stable intraocular pressure control, which can reduce the incidence of secondary complications [20,21].Currently, there is no consensus on the incision for IOFB removal due to the diversity of trauma conditions.In most cases, the IOFB was removed by incision in the corneosclera or through an enlarged trocar opening, which may not maintain the advantages of microsurgical PPV during subsequent surgical procedures [11].
In the present study, we assessed the safety and efcacy of 23 or 25-gauge vitrectomy with modifed pars plana incision for the management of posterior segment IOFB.Te mean BCVA was signifcantly improved from 2.01 ± 0.55 LogMAR to 0.91 ± 0.58 LogMAR (p < 0.001) and anatomical success was achieved in 100% of the cases.Compared to light perception to 20/80 before surgery, visual acuity improved to CF/1 m to 20/33 at the fnal follow-up.BCVA was improved in all patients, except for one patient whose foreign body was removed 1 month later due to delayed discovery (patient no.3).
Te timing of IOFB removal is one of the key factors afecting the clinical prognosis.In some cases, corneal edema and turbidity may interfere with the visibility of the posterior segment, and PPV must be postponed until corneal edema resolves.Poor observation clarity may afect surgical outcomes and increase the risk of iatrogenic lesions, incomplete IOFB resection, and inadequate management of associated ocular injuries, but delayed surgery reduces the chance of visual recovery and increases the risk of complications such as proliferative vitreoretinopathy (PVR), toxic reaction, and endophthalmitis [22,23].Although no endophthalmitis occurred in our study, we recommend that immediate vitrectomy surgical resection should be considered if endophthalmitis is suspected; otherwise, it can be delayed until corneal edema improves and intraocular infammation is better controlled.According to our experience, these processes usually take around 7 days.In addition, if the conditions are met, we do not recommend that the foreign body be removed too late.For our only case where vision did not improve, it may be directly related to the secondary epimacular membrane caused by the excessive delay in IOFB removal (patient no.3).No cases of endophthalmitis were observed in our study.On the one hand, it may be attributed to the prophylactic use of vancomycin (1 mg/0.1 ml) and ceftazidime (2 mg/0.1 ml) intra-vitreous during primary suture.On the other hand, it also refects the safety and efectiveness of microsurgical vitrectomy with pars plana incision for IOFB removal.Days, mean ± SD (range) 6.6 ± 6.9 (1-30) Follow-up Months, mean ± SD (range) 18 ± 6.9 (10-32) Traumatic cataract is a common complication of IOFB patients, with a reported incidence of 44%∼66% [9].In our study, the incidence of traumatic cataract was 37.5%.In order for the posterior segment to be clearly visible, cataract removal is necessary in this case.However, in a signifcant proportion of cases (our study was 50%), a minor damage to the lens may lead to local nonprogressive lens opacity and may not require surgery [16].In our study, all eight patients retained clear lenses when foreign bodies were removed.And seven of them did not need cataract surgery until their last review.Te results show that the modifed incision has certain advantages for patients with transparent crystalline lens.

Journal of Ophthalmology
At present, retinal detachment is the principal cause of visual loss after ocular trauma [24].Despite current advances in treatment technology, retinal detachment before or after surgery remains a common and devastating complication.PVR is the main impact factor on retinal detachment after trauma [19,25,26].IOFB-related retinal detachment occurs in 16 to 47% of patients [27,28].In this study, preoperative retinal detachment occurred in 9 (56.3%)patients.Except for one case of recurrence of retinal detachment caused by PVR due to excessive IOFB (patient no.4), the rest of the patients were successfully reattached.None of the other 7 patients with normal retina before surgery was observed to have retinal detachment during follow-up.Tis also demonstrated the safety of the modifed pars plana incision combined with microsurgical PPV for the removal of IOFB.Removal of foreign bodies through a modifed pars plana incision did not have an adverse efect on the scleral trocar incision.After closing the pars plana incision, the advantages of minimally invasive PPV surgery can be retained and stable intraocular pressure can be maintained, providing a guarantee for the treatment of subsequent lesions.
Where indications are available, we do not recommend removing IOFB without vitrectomy due to the risk of vitreous incarceration and the possible traction damage to intraocular tissues.Shah et al. found that in the process of removing foreign bodies, perfuorocarbon fuids can be used to protect the macula to prevent foreign body shedding and damage [29].In our experience, there was no shedding during the removal of IOFB in all 16 patients, and only in one case of nonmagnetic foreign body, we used perfuorocarbon solution protection.
In this present study, to remove IOFB, we performed a modifed pars plana incision parallel to and 3.5-4 mm behind the limbus at 12 o`clock to preserve trocar position for continued vitrectomy (details shown in the supplementary surgical video https://video.weibo.com/show?fd=1034:4915925892399132).We did not need to enlarge the trocar incision, which avoided incision leakage during the treatment of subsequent lesions and maintained stable intraocular pressure, thus keeping the advantage of minimally invasive surgery.Tis modifed pars plana incision has advantage for patients with intact lens (shown in Figure 1), and it is suitable for IOFBs of diferent sizes and shapes (shown in Figure 2).Compared with clear cornea or limbus tunnel incision, modifed incision through pars plana has less adverse efect on corneal endothelium and lens capsule and will not increase the complications like iatrogenic retinal hole or haemorrhage.Te main limitations of this study include its noncomparative and retrospective design.In order to compare our technique with other methods previously established, randomized controlled studies with larger sample sizes are required.

Conclusions
Nonetheless, in conclusion, microsurgical vitrectomy with a modifed pars plana incision is a safe and efective method for the treatment of posterior segment IOFBs, especially associated with transparent crystalline lens and posterior segment injury.Our procedure showed considerable functional success and low rates of complication.6 Journal of Ophthalmology

Figure 1 :
Figure 1: Patient no. 10 with transparent lens preoperative (a), combined with vitreous hemorrhage (b), clearance of accumulated blood to exposure of foreign body (c), modifed pars plana incision was made (d), removal IOFB through modifed incision with the help of magnet (e and f ), close the modifed incision to maintain intraocular stability for continued vitrectomy (g), lens keep transparent at the end of the operation (h).

Figure 2 :
Figure 2: Modifed incision suitable for IOFBs of diferent sizes and shapes, patient no. 8 with small size IOFB (a) and patient no. 4 with large size IOFB (b).

Table 2 .
At the last follow-up, all IOFBs were successfully removed and all patients were anatomically successful.
3.4.Postoperative Complications.No haemorrhage, choroidal detachment, endophthalmitis, or other signifcant complications were detected in the early postoperative period.At follow-up, a (6.2%) patient underwent reoperation for recurrent retinal detachment and a (6.2%) patient underwent macular epiretinal membrane peeling combined with silicone oil extraction and air tamponade.Two (12.5%) of the silicone oil tamponade patients had transient elevated intraocular pressure which can be well controlled by drug therapy alone.None of the patients had an IOP less than 6 mmHg or eyeball atrophy during follow-up.

Table 1 :
Characteristics of the patients.