Analytical study of silicon oil removal with cataract surgery after vitrectomy

INTRODUCTION

Silicone oil (SO) endo-tamponade is often used in eyes with complicated vitreoretinal pathology (giant retinal tears, diabetic tractional retinal detachment [TRD]), which provides a clear view of the fundus in comparison to gas and inhibits post-operative vitreous haemorrhage, especially in patients with proliferative diabetic retinopathy.^[1] SO has also been shown to decrease the risk of neovascular glaucoma by compartmentalising proangiogenic factors.^[2] SO enables more rapid visual rehabilitation in the immediate postoperative period, relieves the need for strict face-down positioning in patients with neck or back disorders and permits high altitude (e.g., air) travel.^[2]

SOs are used as intraocular tamponades to keep the retina adhered to the retinal pigment epithelium. Key properties affecting their function include specific gravity (0.97), buoyancy, interfacial tension (impacted by viscosity and other fluids) and viscosity (ranging from 1,000 to 5,000 centistokes).^[3,4]

However, complications including cataracts, glaucoma, band keratopathy, emulsification of SO, corneal decompensation and possible neural toxicity restrict it from permanent vitreous substitute. Another important consideration in the use of SO is the need for an additional surgical procedure to remove the oil once stable retinal anatomic status is achieved. The presence of SO expedites cataract progression, and its development may persist even after the removal of the SO.^[5]

This justifies performing proactive cataract surgery along with SO removal.^[1] Cataract can develop in nearly all eyes in which SO remains in situ for few months and up to 60% of lenses that appear relatively clear at the time of SO removal will also develop a clinically significant cataract after 2 years.^[6]

Cataract formation is common after 20-gauge pars plana vitrectomy (PPV), with rates ranging from 12.5% to 80%. Contributing factors include increased oxygen tension, oxidative stress, changes in lens metabolism, inflammatory reaction and trauma.^[7] Small gauge (23- or 25-gauge) PPV may offer reduced risk due to less ocular manipulation and fluid use, though benefits need clinical validation. Cataract types include posterior subcapsular and nuclear cataracts, often developing post-SO removal (SOR).^[8] Combining SOR with cataract surgery is recommended to mitigate complications like posterior capsular opacification, though challenges in IOL power calculation may lead to residual refractive error.^[9] Because of the high incidence of postoperative PCO (seen in more than 50% of patients) after combined phacoemulsification and SOR, primary posterior capsulotomy can be done to prevent PCO but can complicate surgery (retinal detachment [RD], IOL pitting, IOP rise, macular oedema and uveitis.) and increase costs.

SOR and cataract surgery can lead to several complications. Expulsive haemorrhage, though rare, may occur, especially in patients with glaucoma or high myopia.^[10] SOR duration varies with technique; manual removal generally takes less time than traditional methods. Re-detachment of the retina is common, especially in proliferative vitreoretinopathy, and can be linked to post-operative hypotony and vascular issues.^[11] Other risks include vitreous haemorrhage, endophthalmitis and choroidal detachment.^[12]

Several methods are used for combined SOR and cataract surgery. Transpupillary and pars plana methods minimise risks but may cause iris prolapse or hypotony. Three-port vitrectomy effectively reduces detachment risks but poses iatrogenic break risks. The two-step approach offers better retinal evaluation yet increases inflammation and costs.

The study was undertaken with the aim of evaluating refractive status before and after a combined SO removal/cataract extraction with IOL implantation procedure over 3 months.

MATERIALS AND METHODS

This retrospective study encompasses patients who had previously undergone PPV with SO tamponade. Postoperative follow-up assessments confirmed complete retinal attachment along with the presence of a complicated cataract. Written informed consent was obtained from all participating patients.

All patients underwent SOR alongside cataract extraction and intraocular lens (IOL) implantation after undergoing the requisite pre-operative investigations. A single practitioner conducted all pre-operative evaluations, cataract grading and surgical procedures.

The outcome measures assessed in this study included:

• The mean duration between vitrectomy and combined SOR and phacoemulsification

• The rate of post-operative RD

• Best-corrected visual acuity (BCVA)

• Intraocular pressure (IOP) measurements.

A total of 34 patients (34 eyes) were included in the study, all of whom underwent combined SOR and phacoemulsification with IOL implantation. These procedures were performed over a 2-year period (May 2019 to August 2021), with a minimum post-operative follow-up duration of 6 weeks. All vitrectomy surgeries were carried out by a single surgeon at a tertiary care centre. Ethical approval for the study was obtained (reference number: 92/2021).

The indications for vitrectomy and SO injection were restricted to cases of rhegmatogenous RD, traumatic RD and giant retinal tear with associated RD. Indications for SOR included retinal attachment and the stability of SO tamponade for a duration of at least 3 months. Phacoemulsification with IOL implantation was performed when visual acuity (VA) was compromised due to cataracts.

Patient selection was guided by the following criteria:

RESULTS

The average patient age was 52.18 ± 12.58 years, with a range of 25–73 years with a significant gender disparity, the male-to-female ratio being 5.8:1 (29 males and 5 females). The mean duration of SO tamponade was 8.1 months. Cataract development included 58.82% with 2+ nuclear sclerosis and 50% with 2+ posterior subcapsular cataracts. Tractional retinal detachment with proliferative diabetic retinopathy was the most common indication for pars plana vitrectomy and SO tamponade [Figure 1]. Transient post-operative IOP elevations were seen, which were resolved by 6 weeks [Figure 2]. Significant improvement in BCVA was seen in 32.35% patients post-operatively [Figure 3].

Close

Figure 1:

The indications for which patients had to be taken up for vitrectomy with SO tamponade, tractional RD with PDR constituting the main cause for patients undergoing PPV with SO substitution, followed by patients with RRD and GRTs with RD. SO: Silicone oil, GRT: Giant retinal tear, RD: Retinal detachment, VH: Vitreous haemorrhage, RRD: Rhegmatogenous retinal detachment, TRD: Tractional retinal detachment, PDR: Proliferative diabetic retinopathy. PPV: Pars plana vitrectomy.

Export to PPT

Close

Figure 2:

Post-operative IOP exhibited transient elevations, peaking at day 1 (19.242 ± 3.28 mmHg) before normalising to 17.848 ± 2.77 mmHg at 6 weeks. IOP: Intraocular pressure. Values are expressed as Mean ± Standard deviation).

Export to PPT

Close

Figure 3:

Post-operative BCVA showed significant improvement, with 32.35% of patients achieving BCVA ≥ 6/60, while 52.94% stabilised at functional levels. 14.70% had worse BCVA due to complications like retinal re-detachment. BCVA: Best-corrected visual acuity.

Export to PPT

DISCUSSION

This retrospective analysis reviewed 34 patients, with a mean age of 52.18 years (range: 25–73 years), and a male-to-female ratio of 5.8:1. TRD associated with proliferative diabetic retinopathy was the most common indication for prior PPV and SO tamponade, accounting for 41.18% of cases. The mean duration of SO tamponade was 8.09 ± 3.88 months. Comparatively, Xu et al.’s study^[13] reported a duration of 10.5 ± 3.5 months for SO tamponade. Cataract development was influenced by factors such as SO tamponade duration, patient age, trauma and intraoperative factors during prior vitrectomy. Cataracts predominantly exhibited nuclear sclerosis (58.82% had 2+ severity) and posterior subcapsular components. Post-operative assessments indicated transient IOP elevations, peaking shortly after surgery, which resolved by 6 weeks without significant long-term changes. Retinal re-detachment occurred in three patients (8.82%), while the majority (82.35%) achieved stable retinal attachment. BCVA demonstrated significant improvement in 32.35% of patients postoperatively, stabilising in 52.94%, while 14.7% experienced worsening due to retinal re-detachment. Findings align with Cakir et al.^[14] and Krepler et al.,^[15] who observed visual improvement in a substantial proportion of patients post-surgery. Furthermore, a study by Frau et al. evaluated phacoemulsification with SOR via posterior capsulorhexis in 20 patients. Results showed effective outcomes, with a 15% RD recurrence rate and manageable refractive errors (<4.5 dioptres),^[16] supporting our study. An additional study Krepler et al.^[15] compared outcomes of separate versus combined cataract surgery and SOR in 70 patients. Visual improvements and complication rates were similar, but combined surgery offered faster rehabilitation and convenience for stable retinal cases, reducing the surgical burden for appropriately selected patients, thereby supporting our discussion. This approach highlights the importance of careful pre-operative planning and patient selection to optimise outcomes and minimise complications.

CONCLUSION

This study underscores the advantages of performing SOR and cataract surgery as a combined procedure. This approach facilitates expedited visual rehabilitation and reduces invasiveness compared to the traditional two-stage surgical method. It has proven particularly effective for patients with stable retinal conditions, highlighting the importance of tailoring the evaluation process to the patient’s specific underlying pathology and prior interventions, rather than relying solely on standardised timing criteria for SOR and cataract extraction.