Central scotoma associated with intraocular silicone oil tamponade develops before oil removal

Contamination Profile of Different Formulations of Silicone Oil Tamponade Before and After Intraocular Permanence for Rhegmatogenous Retinal Detachment

Purpose

The purpose of this study was to search for contaminants in silicone oil tamponades removed from eyes treated for retinal detachment, and to correlate chemical results with some clinical/functional parameters of the considered eyes.

Methods

We examined a sequential cohort of eyes grouped according to the tamponade received: (1) Siluron2000 (S2), (2) RS-OIL ECS5000 (S5), and (3) Densiron Xtra (DX). Samples were collected at the beginning of the scheduled removal and analyzed by untargeted headspace gas-chromatography mass spectrometry (HS-GC-MS). Visual acuity and optic coherence tomography assessments were obtained before and after the tamponade removal.

Results

Forty-one samples were analyzed: 22 belonging to the DX group, 13 to the S2 group, and 6 to the S5 group. For each group, a mixture of uninjected commercial preparation was analyzed as the reference. Different siloxanes and fluorinated compounds including perfluorodecalin (PFCL) were the most prevalent chemicals, found in 55% to 100% of the intraocular samples of the 3 groups. Some siloxanes were present also in the control matrices, whereas PFCL was only in the extracted tamponades. In the DX group, the concentration of hexamethylcyclotrisiloxane showed an inverse correlation trend with the duration of its permanence inside the eye (P = 0.054). Different alkanes, propanol, and acetaldehyde were identified only in the control matrices.

Conclusions

Several contaminants including siloxanes were identified in the intraocular samples and in the control matrices. A time-related ocular uptake of some of these is conceivable. PFCL was also highly present but only in intraocular samples.

Translational Relevance

After intraocular permanence silicone oils (SOs) have various unlabeled contaminants with some relevant differences with the commercial formulation chemical profile.

An ex vivo headspace gas chromatography-mass spectrometry method for the determination of short-chain siloxanes in silicon oil tamponades used in ophthalmic surgery

Being able to facilitate retinal reattachment by preventing water migration into the subretinal space, silicone oils are widely used as long-term intraocular tamponade to treat cases of retinal detachment. Various commercial tamponades constituted by linear polydimethylsiloxane polymers with different molecular weights and cyclic impurities are available. In this study, for the first time, an untargeted headspace-gas-chromatography-mass spectrometry (HS-GC-MS) method was developed to identify low-molecular weight contaminants in three different types of silicone oil tamponades, namely Siluron 2000, RS-OIL ECS5000 and Densiron Xtra. Both commercial and post-operative tamponades were analysed to screen for the different classes of compounds present in the samples. The most abundant classes were short-chain siloxanes, fluorinated compounds, and hydrocarbons. To quantify the siloxanes present in the samples, a targeted HS-GS-MS was optimized using a central composite design and validated according to guidelines for bioanalytical methods. Lower limits of quantification in the low μg/L range, good precision with RSD% < 12% and accuracy with recovery rates in the 81 ( ± 7) - 96 ( ± 4) % range were achieved. Short-chain siloxanes were quantified in both commercial and post-operative tamponades, being the RS-OIL ECS5000 characterized by the highest concentration levels of the investigated analytes. By contrast, Densiron Xtra tamponades showed the lowest amount of short-chain siloxanes, observing a general decrease in their concentration levels according to the residence time in the eyes.

Unexplained Vision Loss Associated With Intraocular Silicone Oil Tamponade in Rhegmatogenous Retinal Detachment Repair

Purpose: To evaluate the visual outcomes with unexplained vision loss during or after silicone oil (SO) tamponade. Methods: This multicenter retrospective case series comprised patients with unexplained vision loss associated with SO tamponade or its removal. Eyes with other clear secondary identifiable causes of vision loss were excluded. Results: Twenty-nine eyes of 28 patients (64% male) were identified. The mean age was 50 ± 13 years (range, 13-78 years). The mean duration of SO tamponade was 148 ± 38 days. Eighteen eyes (62%) developed unexplained vision loss while under SO; 11 (38%) had vision loss after SO removal. The most common optical coherence tomography (OCT) finding was ganglion cell layer (GCL) thinning (55%). Eyes with vision loss after SO removal had a mean logMAR best-corrected visual acuity (BCVA) of 0.6 ± 0.7 (Snellen 20/85) before SO tamponade and 1.2 ± 0.4 (20/340) before SO removal. By the last follow-up after SO removal, the BCVA had improved to 1.1 ± 0.4 (20/235). In eyes with vision loss after SO removal, the BCVA before SO removal was 0.7 ± 0.7 (20/104), which deteriorated to 1.4 ± 0.4 (20/458) 1 month after SO removal. By the last follow-up, the BCVA had improved to 1.0 ± 0.5 (20/219). Conclusions: Unexplained vision loss can occur during SO tamponade or after SO removal. Vision loss was associated with 1000-centistoke and 5000-centistoke oil and occurred in macula-off and macula-on retinal detachments. The duration of tamponade was 3 months or longer in the majority of eyes. Most eyes had GCL thinning on OCT. Gradual visual recovery can occur yet is often incomplete.

Assessment of Silicone Oil Emulsification: A Comparison of Currently Applied Methods

Purpose

To compare ultrasound biomicroscopy (UBM), Coulter counter, and B-scan ultrasonography in the evaluation of silicone oil (SO) emulsification.

Methods

Patients who underwent primary pars plana vitrectomy with SO tamponade for rhegmatogenous retinal detachment and SO removal were included. UBM images were acquired before the SO removal, and B-scan images were taken after removal. The number of droplets in the first and last 2 mL of washout fluid was analyzed using a Coulter counter. The correlations between these measurements were analyzed.

Results

Thirty-four eyes received both UBM and Coulter counter analysis for the first 2 mL of washout fluid, and 34 underwent B-scan and Coulter counter analysis of the last 2 mL washout fluid. The mean UBM grading was 26.41 ± 9.71 (range: 1-36); the mean SO index obtained with B-scan was 5.25 ± 5.00% (range: 0.10-16.49%), and the mean number of SO droplets was 1.26 ± 2.45 × 10⁷/mL and 3.34 ± 4.22 × 10⁶/mL in the first and last 2 mL of washout fluid, respectively. There were significant correlations between UBM grading and SO droplets in the first 2 mL and between B-scan grading and SO droplets in the last 2 mL (all P < 0.05).

Conclusions

UBM, Coulter counter, and B-scan ultrasonography could all be used in the evaluation of SO emulsification, and their findings were comparable.

A reminder about silicone oil toxicity: three cases over five years in a tertiary hospital

PURPOSE

Presumed silicone oil-related retinal toxicity causes central vision loss with a reported incidence of 1-33% in the first month after oil removal and 10% in the first six months of having silicone oil in-situ. This report examines local rates in a tertiary hospital that manages many geographically distanced patients. A miniature literature review, audit and case series are presented.

METHODS

A retrospective audit of all patients who underwent a 'removal of silicone oil' surgery at the Royal Brisbane and Women's Hospital between 2016 and 2021. Inclusion criteria were that the oil was inserted for primary or recurrent rhegmatogenous retinal detachment. Visual acuity was analysed at presentation, at 1 and 3 months of oil in-situ, preoperatively to removal of oil and up to 6 months after oil removal. Ocular coherence tomographic parameters were examined at each time interval, including nerve fibre layer (NFL) and ganglion cell layer and inner plexiform layer (GCL + IPL) thicknesses in the 3 mm parafoveal zone, presence of inner retinal microcystic changes or intraretinal silicone oil globules. Patients were identified who had unexplained vision loss of two or more Snellen lines. Further analysis and case review were performed.

RESULTS AND CONCLUSIONS

Between January 2016 and May 2021, 101 patients met the inclusion criteria. Three patients had significant and unexplained visual loss. They are presented in this paper. Presumed silicone oil toxicity is an increasingly recognised and potentially devastating phenomenon that vitreo-retinal surgeons should be wary of. Patients should be specifically consented for it and hospitals should perform local auditing to determine their own rates and inform this discussion.

Retinal and Corneal Changes Associated with Intraocular Silicone Oil Tamponade

Silicone oils (SO) are used as long-term intraocular tamponades and have an irreplaceable role in vitreoretinal surgery. They can, however, be associated with multiple and potentially severe complications, involving different ocular tissues, in particular retina and cornea. Recent advances in ophthalmic imaging have allowed the precise characterization of retinal and corneal microstructural changes, at a subclinical level. This detailed analysis of SO-related retinal and corneal changes has improved our understanding of their pathogenesis and offer the potential for optimized monitoring and management of patients with SO-filled eyes. This review aims to provide clinicians and ophthalmic scientists with an updated and comprehensive overview of the corneal and retinal changes associated with SO tamponade.

[Visual acuity reduction and silicone oil tamponade]

Silicone oil is an established intraocular surgical aid, which enables the treatment of the most complex starting situations but no other alternative has been found; however, the available data indicate that an unclear loss of visual acuity during or after an intraocular silicone oil tamponade possibly occurs more frequently than assumed from the clinical routine. Various pathological mechanisms are under discussion as causes, but the exact causes are actually unclear. In addition to atrophic alterations in the optical coherence tomography (OCT) examination, there are a clear reduction in visual acuity and mostly a central scotoma with otherwise inconspicuous findings. Unclear loss of visual acuity can also occur after removal of the silicone oil. Whether this is caused by the same pathological mechanism is unclear. Furthermore, there are no reproducible risk factors that appear a priori to possibly cause an unclear loss of vision under silicone oil; however, oil removal as soon as possible and a good adjustment of the intraocular pressure are recommended by the authors. Overall, a silicone oil tamponade should be carefully weighed up even when using modern highly purified silicone oils and it should therefore continue to be reserved particularly for unfavorable initial situations or complicated courses with the necessity for a silicone oil tamponade. Against this background, a study for systematic recording and processing of cases of unclear loss of visual acuity after silicone oil tamponade seems to be meaningful.

Effect of vitrectomy with silicone oil tamponade and internal limiting membrane peeling on eyes with proliferative diabetic retinopathy

We investigated the combined effect of silicone tamponade and the internal limiting membrane (ILM) peeling and investigated whether timing of peeling of the ILM affects the outcomes of vitrectomy with silicone oil tamponade in eyes with proliferative diabetic retinopathy (PDR). Here, we examined 63 eyes (58 patients) with PDR, which underwent vitrectomy with silicone oil tamponade and stepwise removal of silicone oil. ILM peeling was performed just before oil injection (group 1; 33 eyes, 30 patients) or after oil removal (group 2; 30 eyes, 28 patients). Visual acuity and retinal and choroidal thicknesses were compared between the groups. Thinning of the inner retina, including the ganglion cell-inner plexiform layer and macular retinal nerve fiber layer, was evident at 1 year after surgery in both groups. Thinning of the total retina (P = 0.019) and inner retina (P = 0.008) was significantly correlated with final visual acuity. There was no considerable between-group difference observed in final visual acuity, intraocular pressure, or retinal or choroidal thickness at 1 year after surgery. The incidence of epiretinal membrane was higher during silicone endo-tamponade in group 2 (P = 0.033). Visual recovery and macular configuration in eyes with PDR are not affected by whether the ILM is peeled before or after silicone oil tamponade.

Longitudinal evaluation of retinal thickness and OCTA parameters before and following silicone oil removal in eyes with macula-on and macula-off retinal detachments

BACKGROUND

To investigate the longitudinal retinal vascular and structural alterations by using OCTA following successful repair of retinal detachment (RD) by using silicone oil (SO) endotamponade.

METHODS

A prospective cohort study was performed on 24 eyes of 24 subjects; 17 of them with macula-off and seven with macula-on RD. At least four OCTA scans were generated for each study eye; two before and two after SO removal (SOR). At each session, retinal thickness (RT), vascular density (VD) in the superficial (SCP) and deep capillary plexuses (DCP) and foveal avascular zone(FAZ) size were measured within the fovea, parafovea and whole macular image. The changes in repeated measures of the same parameters especially before and after SOR were performed and compared within macula-on and macula-off groups and between fellow eyes.

RESULTS

"In the macula-off eyes, RT measurements within the whole macula, fovea and parafovea reduced as compared with their fellow eyes(p < 0.0001, p = 0.001 and p < 0.0001, respectively) and did not improve after SOR. Additionally, all of the whole macular, foveal, and parafoveal VD measurements at SCP and foveal VD at DCP were less than their fellow eyes after SOR (p = 0.026, p = 0.023 p = 0.026, and p = 0.002, respectively). In macula-on eyes, RT measurements decreased within the parafovea and whole macular area before SOR (p = 0.018 and p = 0.011, respectively) but improved after SOR. Also, VD measurements did not change during follow-up and were not statistically different than their fellow eyes (p > 0.05). FAZ enlargement was found in eyes with macular-off RD after SOR, whereas it was not observed with macular-on RD (p = 0.038and p = 0.237, respectively).

CONCLUSIONS

Treatment of macula-off RD with SO tamponade has been associated with vascular retinal abnormalities which did not improve following SOR. On the contrary, successful treatment of RD with SO tamponade in macula-on eyes VD measurements of SCP and DCP were not statistically different than their fellow eyes.

What Is the Cause of Toxicity of Silicone Oil?

Purpose: To investigate the toxicity of the low-molecular-weight components (LMWCs) in ophthalmic silicone oils (SilOils) on retinal cell lines. Methods: The toxicity of six types of LMWCs were studied and compared with conventional SilOil 1000 cSt. In vitro cytotoxic tests of LMWCs, in both liquid and emulsified forms, on three retinal cell lines (Müller cells (rMC-1), photoreceptor cells (661W) and retinal pigment epithelial cells (ARPE-19)) were conducted using a transwell cell culturing system. The morphology and viability of cells were assessed by light microscopy and Cell Counting Kit-8 (CCK-8) assay at different time points (6, 24 and 72 h). The ARPE-19 apoptotic pathway was investigated by Mitochondrial Membrane Potential/Annexin V Apoptosis Kit at different time points (6, 24 and 72 h). Results: Apart from dodecamethylpentasiloxane (L5), all liquid LMWCs showed varying degrees of acute cytotoxicity on retinal cell lines within 72 h. Emulsified LMWCs showed comparable cytotoxicity with liquid LMWCs on retinal cell lines. Cyclic LMWCs, octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) had significantly higher cytotoxicity when compared with their linear counterparts decamethyltetrasiloxane (L4) and L5 with similar molecular formula. Using ARPE-19 cells as an example, we showed that LMWCs induce the apoptosis of retinal cells. Conclusions: Most LMWCs, in both liquid and emulsified forms, can induce acute cytotoxicity. In addition, cyclic LMWCs are suspected to have higher cytotoxicity than their linear counterparts. Therefore, LMWCs are suspected to be the main cause of the long-term toxicity of ophthalmic SilOil, due to their toxicity and propensity to cause ophthalmic SilOil to emulsify. The amount of LMWCs should be considered as the paramount parameter when referring to the quality of SilOil.

DIA Comparative Proteomic Analysis of Retro-oil Fluid and Vitreous Fluid From Retinal Detachment Patients

Objectives: There have been reports of unexplained visual loss following intra-ocular silicone oil (SiO) tamponade in retinal detachment patients, yet the underlying mechanism is unknown. The aim of this study was to investigate the mechanisms behind retinal toxicity following intra-ocular SiO tamponade in retinal detachment patients. Methods and Results: Vitreous fluid samples were acquired from 27 patients (27 eyes). Twelve eyes for data-independent acquisition (DIA) were divided into four groups: pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RD group), SiO removal after successful retinal reattachment (SO group), cataract surgery after successful retinal reattachment with sterilized air tamponade (FA group), and PPV for epiretinal membrane (ERM group). The remaining 15 eyes were used for enzyme-linked immunosorbent assay analysis. DIA was combined with two-dimensional liquid chromatography-tandem mass spectrometry to find expression changes in the proteome of vitreous. Mean number mass spectra, statistically differentially expressed proteins, gene ontology (GO), pathway representations, and protein interactions were analyzed. GO analysis showed that the protein categories of synapse organization, cell adhesion, and regulation of cell migration in the SO group were differentially expressed compared to the control or FA groups (p < 0.05). Through Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, lysosome and cell adhesion were found to be significantly enriched in the SO group compared to the FA and control groups (p < 0.05). Cadherin 2, transferrin, and lysosome function may partially contribute to silicone oil-related vision loss. Conclusion: Vision loss-inducing novel molecular signatures and pathways that may be associated with SiO toxicity were identified. Transferrin may be a potential visual outcome biomarker for SiO tamponade.

The effect of silicone oil tamponade on retinal layers and choroidal thickness in patients with rhegmatogenous retinal detachment: a systematic review and meta-analysis

Background

To evaluate the effects of intravitreal silicone oil (SO) on the retinal and choroidal thickness in eyes with rhegmatogenous retinal detachment (RRD).

Methods

A literature search was performed in Web of Science, Scopus, ProQuest, Embase, Clinical Key, Science Direct, Cochrane Library, and Springer, as well as Persian databases, including IranDoc, MagIran, SID, MOH thesis, and MOH articles until June 2020. Two reviewers independently searched and extracted the data.

Results

Sixteen studies (n = 391) met the inclusion criteria. The meta-analysis showed that the SO tamponade could significantly reduce the central macular thickness (CMT) in patients with RRD as compared to gas tamponade WMD = − 14.91; 95% CI: − 22.23, − 7.60; P < 0.001, I² = 71%). No significant change was found in CMT between the eye with SO tamponade (after SO removal) and the fellow healthy eye in patients with RRD (WMD = − 3.52; 95% CI: − 17.63, 10.59; I² = 68.6%). Compared to the preoperative stage, the SO tamponade could significantly reduce the subfoveal choroidal thickness in patients with RRD (WMD = − 18.67, 95% CI: − 30.07, − 1.28; I² = 80.1%). However, there was no significant difference in the subfoveal choroidal thickness before and after SO removal (WMD = − 1.13, 95% CI: − 5.97, 3.71; I² = 87.6%).

Conclusion

The SO tamponade had a significant effect on the reduction of retinal layers and the subfoveal choroidal thickness.

Changes of macular vessel density and thickness in gas and silicone oil tamponades after vitrectomy for macula-on rhegmatogenous retinal detachment

Purpose

To investigate the macular vessel density and thickness in macular-on rhegmatogenous retinal detachment (RRD) after vitrectomy with gas and silicone oil (SO) tamponade.

Methods

Patients with macular-on RRD eyes, treated with a single successful vitrectomy with gas or SO tamponade and a minimum 30 months follow-up, were reviewed. Best-corrected visual acuity (BCVA), macular vessel density and retinal thickness by using optical coherence tomography angiography, were compared to the contralateral eyes.

Results

Sixteen eyes with gas tamponade and 17 eyes with SO tamponade were included in the study. LogMAR best-corrected visual acuity (BCVA) slightly improved from 0.25 ± 0.18 (Snellen 20/36) to 0.17 ± 0.23 (Snellen 20/30) in eyes with gas tamponade, and decreased from 0.30 ± 0.22 (Snellen 20/40) to 0.49 ± 0.28 (Snellen 20/62) in eyes with SO tamponade. The parafoveal vessel densities in superficial vascular complex (SVC) and the corresponding inner retinal thickness (IRT) were similar between the affected eyes and the contralateral eyes in gas tamponade group (P = 0.578, P = 0.943), while significantly reduced in the affected eyes, compared to the contralateral eyes in SO tamponade group (P < 0.001, P < 0.001).

Conclusion

Eyes in SO tamponade group had worse BCVA, lower SVC vessel densities and thinner corresponding IRT after vitrectomy for macular-on RRD, than those in gas tamponade group.

Silicone oil versus gas tamponade for primary rhegmatogenous retinal detachment treated successfully with a propensity score analysis: Japan Retinal Detachment Registry

Background/aims

To compare the effects of silicone oil tamponade (SOT) to that of gas tamponade (GT) on the best-corrected visual acuity (BCVA) after successful vitrectomy for retinal detachment (RD).

Methods

A retrospective, multicentre, nationwide study with RD who were registered in the Japan-RD Registry. All cases with RD treated with successful vitrectomy between February 2016 and March 2017 were studied. A propensity score matching was performed using the preoperative findings as covariates to adjust the relevant confounders. The primary outcome was the estimated mean difference of the postoperative BCVA in 6 months between eyes treated with SOT to those treated with GT.

Results

Of the 3446 cases registered, 2097 cases met the entry criteria. There were 2042 eyes that had GT and 55 eyes that had SOT. Primary success was defined as a reattached retina with no tamponade at 6 months. After propensity score matching, each group contained 40 cases. The preoperative BCVA was 0.966±0.738 logMAR units in the GT group and 1.270±0.945 logMAR units in the SOT group (p=0.177). Six months postoperatively, the BCVA in the GT group was significantly better at 0.309 logMAR units in the GT group than the 0.671 logMAR units in the SOT group (p=0.002).

Conclusions

Even after successful surgery for RD, eyes that experienced SOT had poorer BCVA than eyes treated with GOT. SOT should be considered cautiously.

Precis

Propensity score analysis of eyes with rhegmatogenous RD showed that postoperative vision was worse in eyes treated once with silicone oil than with gas even after completely successful surgery.

UNEXPLAINED VISUAL LOSS AFTER GAS TAMPONADE FOR MACULA-ON RETINAL DETACHMENT: Incidence and Clinical Characterization

PURPOSE

To identify the incidence rate and the clinical characteristics of unexplained visual loss after gas tamponade for primary macula-sparing rhegmatogenous retinal detachment.

METHODS

Retrospective longitudinal analysis of all subjects undergoing vitrectomy with gas for primary macula-on rhegmatogenous retinal detachment from 2010 to 2019. Outcome was the unexplained visual loss evaluated after gas absorption, defined as a loss of vision to less than 20/200 without evident causes. The diagnostic workup was reviewed.

RESULTS

Nine eyes with unexplained visual loss of 357 surgeries were found. The incidence proportion was 2.52 new cases every 1,000 eyes affected by macula-on rhegmatogenous retinal detachment treated with gas per year. All subjects had an absolute central scotoma, with a median postoperative visual acuity of 20/1,600 (counting fingers). Structural findings were consistent with an axonal damage; all eyes had microcystoid macular edema and reduced thickness of both macular ganglion cell and retinal nerve fiber layers. No photoreceptor structural damages were noted.

CONCLUSION

The incidence of unexplained visual loss after gas tamponade for primary macula-on rhegmatogenous retinal detachment is 2.52 new cases every 1,000 eyes per year. This rare complication, which findings are suggestive of an axonal damage within retinal ganglion cells, remains a serious and unexplained concern for vitreoretinal surgeons.

[Changes in perfusional and morphological parameters of the macular area after silicone oil tamponade of the vitreous cavity]

PURPOSE

To compare the changes of the macular morphological and functional parameters in the postoperative period in patients with silicone oil tamponade after successful surgery of the macula-on rhegmatogenous retinal detachment (RRD).

MATERIAL AND METHODS

The study included 20 eyes operated on for macula-on RRD, which made up the first group, and the control group (20 eyes) for comparison. All patients of the study group underwent vitrectomy using silicone oil tamponade. Standard ophthalmological examination was performed on the 3rd day (early postoperative period) and the 14th day (late postoperative period), including OCT and OCT-A that were used to assess morphological and functional changes.

RESULTS

A significant decrease in visual acuity was seen on the 3rd day after surgery involving the use of silicone oil tamponade, in comparison with the 14th day (p=0.0237) and the control group (p=0.0001). A decrease in the FD parameter (p=0.045), a decrease in vascular density in the fovea (p=0.020) and parafovea (p=0.024) in SCP were found on the 3rd day in comparison with control. On the 14th day of postoperative observation, a tendency was detected for choroidal perfusion to restore, as well as significant increase in FD (p=0.016), and an increase in vascular density in parafovea (p=0.01) compared with the early postoperative period. No statistically significant changes were seen in the FAZ area and vessel density DCP (p>0.05).

Intraocular Pressure Rise Linked to Silicone Oil in Retinal Surgery: A Review

Silicone oil represents the main choice for intraocular tamponade in cases of complicated retinal detachment surgery. The intraocular pressure of an eye filled with silicone oil could increase, driven by a variety of different forces, according to several mechanisms. Two main conditions have been highlighted, depending on the onset: early hypertension or late glaucoma. The different types of silicone oils and their physico-chemical properties are varied and may play a role in the determination of intraocular pressure rise. The current body of literature allows for the illustration and categorization of the incidence and risk factors, as well as the pathogenesis and the management of the early postoperative hypertension subtended by an open- and closed-angle, along with the late onset silicone oil-induced glaucoma. Understanding the leading actors on the stage of ocular pressure elevation concurrently with silicone oil application for retinal surgery could help in guiding the timely and appropriate course of treatment.

Unexplained Visual Loss After Silicone Oil Removal: A 7-Year Retrospective Study

Introduction

Unexplained visual loss after removal of silicone oil from the eye has been described. The purpose of this study is to determine the incidence of unexplained loss of visual acuity after SO removal and to provide possible explanations for this phenomenon.

Methods

This retrospective study included patients that underwent vitreoretinal surgery, at Centro Hospitalar São João, between January of 2012 and October of 2018. Inclusion criterion was vitreoretinal surgery in which the chosen endotamponade was SO, followed by removal of SO and exchange with balanced salt solution (BSS) or air. After SO removal, patients with documented loss of best corrected visual acuity (BCVA) on two or more Snellen lines were analyzed and patients in which the cause of the visual loss was identified, namely OHT (intraocular pressure > 21 mmHg), retinal re-detachment, glaucoma, retinal proliferative membrane formation, or corneal decompensation, were excluded. All patients with unexplained visual loss underwent spectral domain optical coherence tomography (SD-OCT) to exclude causes of visual reduction such as cystoid macular edema, epiretinal membrane, or ellipsoid/interdigitation zone disruption. A p value less than 0.05 was considered statistically significant.

Results

A total of 46 eyes underwent SO tamponade and SO removal during the study period. In 34.8% of the cases (n = 16) there was visual acuity loss in at least two Snellen lines. Of 46 eyes, 23.9% (n = 11) showed vision loss due to known secondary causes. Unexplained loss of visual acuity after SO removal occurred in 10.9% of cases. OHT during silicone endotamponade (p = 0.046) and silicone emulsification (p = 0.001) were identified as factors associated with unexplained visual loss after SO removal.

Conclusion

Unexplained loss of visual acuity after SO removal occurred in 10.9% of cases. OHT during silicone endotamponade and SO emulsification were identified as important factors in the ethology of this phenomenon.

Optical coherence tomography angiography changes in macula-off rhegmatogenous retinal detachments repaired with silicone oil

PURPOSE

To evaluate the changes on optical coherence tomography angiography (OCTA) in macula-off rhegmatogenous retinal detachments (RRD) treated with pars plana vitrectomy (PPV) and silicone oil (SO) 5000-cSt tamponade.

MATERIALS AND METHOD

Forty-five eyes with macula-off RRD treated with PPV and SO tamponade were enrolled with the fellow eye being used as a control. OCT-A was obtained using the RTVue XR 100 Avanti (Optovue, Inc., Fremont, CA, USA) at the 1-week, 1-month, and 3-month postoperative visit. Retinal vascular density, choroidal flow area, retinal thickness, and foveal avascular zone area were evaluated at each follow-up visit. Changes in these parameters in the postoperative eye were tracked at each follow-up visit as were the relative differences between the postoperative eye and the contralateral eye.

RESULTS

Vascular density of parafoveal superficial capillary plexus and total retina demonstrated significant decrease in the postoperative silicone-filled eye when compared to the fellow eye (P < 0.0001). Although there was some improvement in these values at subsequent follow-ups, they remained less than the fellow eye. Foveal (P = 0.002) and parafoveal (P < 0.0001) thickness were less than the fellow eye. Choroidal flow area did not show a significant change in operated eye compared with the fellow eye.

CONCLUSION

Eyes with macula-off RRD repaired with PPV and SO, at 3-month follow-up, demonstrated less retinal vascular density at parafoveal area as well as lower retinal thickness at fovea when compared to the healthy fellow eyes.

Comparison of fundus changes following silicone oil and sterilized air tamponade for macular-on retinal detachment patients

BACKGROUND

To investigate different tamponade effects of intravitreal silicone oil (SO) and sterilized air on macular vasculature and structure after successful retinal repair for macular-on rhegmatogenous retinal detachment (RRD) patients.

METHOD

21 eyes (21 patients) with macular-on RRD underwent single pars plana vitrectomy following intravitreal SO or sterilized air (Gas) tamponade. Optical Coherence Tomography (OCT) and angiography were used to evaluate retinal layer thickness and flow density (FD) changes throughout the observation period of 12 weeks. Retinal layers were segmented into 7 sets: NFL, GCL + IPL, INL, OPL, ONL + IS, OS+RPE and BRM. Macular perfusion system was segmented into superficial and deep capillary plexus flow density (SCPFD, DCPFD), and choriocapillaries plexus flow density (CCPFD).

RESULT

Compared to Gas tamponade, SO tamponade led to more decrease in both superficial and deep retinal blood flow during observation. NFL thickness was found to decrease in both Gas tamponade and SO tamponade eyes. SO tamponade resulted in more pronounced decrease which led to significant intergroup difference. Opposite changing trends were found in GCL + IPL and ONL + IS thicknesses due to different means of tamponade. SO tamponade caused thicknesses of these two segmented layers to decrease, which led to significant intergroup differences. SO tamponade also led to more decrease in INL, OPL thicknesses. No significant intergroup difference of choroidal thickness was observed.

CONCLUSION

Compared to gas, silicone oil could have more negative tamponade effects on both fundus vasculature and structure.

PREOPERATIVE AND POSTOPERATIVE MACULAR SENSITIVITY ASSESSMENT USING MICROPERIMETRY IN EYES UNDERGOING SILICONE OIL REMOVAL

PURPOSE

To evaluate the functional changes on the macula, before and after silicone oil removal (SOR) using microperimetry (MP3) in patients originally operated for macula-off rhegmatogenous retinal detachments.

METHODS

Prospective interventional study, N = 20. All cases underwent complete ophthalmic examination, including determination of Snellen best-corrected visual acuity, indirect ophthalmoscopy, and MP3 for measuring retinal sensitivity. Primary outcome measure was to describe the alterations in the retinal sensitivity on the macula after SOR.

RESULTS

Mean retinal sensitivity increased in 100% patients (20/20) after SOR with a mean value of 97.44 dB. Best-corrected visual acuity after SOR remained unchanged in 90% (18/20) and improved by 2 lines in only 10% patients (2/20). Median retinal sensitivity of central 6° of the macula was 766.95 ± 173.29 dB before SOR and 863.8 ± 181.08 dB after SOR, P < 0.0001. Mean best-corrected visual acuity was 20/40 before SOR (range, 20/30-20/60) (logarithm of the minimum angle of resolution 0.314 ± 0.169) and 20/40 after SOR (range 20/30-20/80) (logarithm of the minimum angle of resolution 0.315 ± 0.159), P = 0.1628.

CONCLUSION

MP3 was found to be a highly sensitive tool in detecting increased retinal sensitivity after SOR, particularly in central 6° of the macula without significant change in best-corrected visual acuity. Hence, MP3 is an important qualitative indicator of visual function.

Retinal Sensitivity before and after Silicone Oil Removal Using Microperimetry

The purpose of the study is to assess the retinal sensitivity, using microperimetry, before and after silicone removal. It included 22 patients admitted for silicone removal after vitrectomy for macula-off retinal detachment. Patients were divided into 2 groups according to the duration of silicone tamponade: Group A: <3 months (included 10 patients), and Group B: 3–6 months (included 12 patients). Retinal sensitivity was tested, using microperimetry, one day before and one month after silicone removal. The best-corrected visual acuity (in LogMAR) significantly improved postoperatively (0.69 versus 1.06 and 0.69 versus 1.07 in Groups A and B, respectively). The mean intraocular pressure (IOP) was 12.89 ± 1.05 mmHg postoperatively versus 14.89 ± 1.76 mmHg preoperatively in Group A (p=0.011) and was 13.33 ± 1.30 mmHg postoperatively versus 15.33 ± 3.11 mmHg preoperatively in Group B (p=0.008). In Group A, the mean postoperative overall retinal sensitivity was 8.70 ± 2.56 dB versus 5.68 ± 2.00 dB preoperatively (p=0.008). In Group B, it was 9.83 ± 3.36 dB versus 7.00 ± 2.55 dB (p=0.002). No statistically significant difference was found between the two groups as regards improvement in overall retinal sensitivity. We concluded that the overall retinal sensitivity significantly increased following silicone removal in both groups. This trial is registered with ISRCTN43187564.

SILICONE OIL TAMPONADE EFFECT ON MACULAR LAYER THICKNESS AND VISUAL ACUITY

PURPOSE

To evaluate the influence of silicone oil (SO) tamponade on retinal layers thickness and visual acuity in patients who underwent pars plana vitrectomy for rhegmatogenous retinal detachment.

METHODS

This is a retrospective case series of consecutive patients who underwent pars plana vitrectomy for rhegmatogenous retinal detachment with SO tamponade. Visual acuity and central macular thickness were measured with SO and at least a month after SO removal (SOR). Patients with insufficient or poor-quality images or macular pathologies such as macular edema or epiretinal membranes were excluded.

RESULTS

Forty-one patients with an average age of 56.1 ± 15.2 years were included, and 54% presented with fovea ON. Average tamponade duration was 151 ± 54 days. Central macular thickness of the operated eye increased from 249 ± 50 µm before to 279 ± 48 µm after SOR (P < 0.001), compared with 281 ± 21 µm of the fellow eye (P < 0.001). A mean change of 26 µm was found in the internal layers (P < 0.001). Visual acuity improved from 0.85 ± 0.97 logarithm of the minimal angle of resolution (logMAR; Snellen 20/140) with SO tamponade to 0.34 ± 0.28 logMAR (Snellen 20/43) after SOR (P < 0.001). For patients with fovea ON and without significant cataract, visual acuity was 0.19 ± 0.16 logMAR (Snellen 20/30) at presentation, 0.59 ± 0.41 logMAR (Snellen 20/80) with SO (P = 0.005), and 0.18 ± 0.15 logMAR (Snellen 20/30) after SOR (P = 0.003).

CONCLUSION

Silicone oil tamponade causes a transient decrease in central macular thickness, mainly in the inner layers. After SOR, central macular thickness resembles to the fellow eyes. The mechanism for this effect is unclear, but apparently has no influence on final visual acuity.

Retinal sensitivity following intraocular silicone oil and gas tamponade for rhegmatogenous retinal detachment

PURPOSE

To investigate whether intraocular silicone oil (SO) tamponade is associated with functional changes in patients with both macula-on and macula-off rhegmatogenous retinal detachments (RRDs).

METHODS

Prospective observational cohort study of patients with RRD treated by vitrectomy with gas or SO tamponade at the University Medical Center Utrecht. Outcome was best-corrected visual acuity (BCVA) and retinal sensitivity on microperimetry 2 months after surgery.

RESULTS

In total, 40 eyes were included. There are 10 eyes in each of the following groups: macula-on RRD and gas, macula-on RRD and SO, macula-off RRD and gas, and macula-off RRD and SO. Median retinal sensitivity on microperimetry was decreased following SO tamponade compared to gas tamponade for both macula-on and macula-off RRD (p < 0.037).

CONCLUSION

Foveal sensitivity was decreased in eyes after SO tamponade compared to gas tamponade. These effects were observed in patients with macula-on as well as macula-off RRD. Although further investigation is warranted to validate our results and to study underlying mechanisms, retinal surgeons need to be aware of these findings after the use of SO tamponade.

Macular Changes on Optical Coherence Tomography Before, During, and After Silicone Oil Tamponade for Macula-On Retinal Detachment: A Case Series

Purpose:

Assess changes on spectral domain optical coherence tomography (OCT) before, during, and after removal of silicone oil (SO).

Methods:

Retrospective series of patients who underwent SO tamponade for macula-on rhegmatogenous retinal detachment. OCT scans of the affected eye were taken before, during, and 3 months after SO tamponade. Qualitative assessment of foveal contour and quantitative comparison of OCT parameters (central macular, cube, ganglion cell layer [GCL], and outer retinal thicknesses) were done between 3 time points.

Results:

Ten eyes of 9 patients were included. Flattening of the foveal contour during SO tamponade was completely reversed after SO removal. Average cube and GCL thicknesses decreased with SO tamponade and increased after SO removal ( P = .01 and P = .02, respectively). Outer retinal thicknesses did not vary among 3 time points ( P = .09).

Conclusions:

SO tamponade causes foveal flattening and thinning of the inner retinal layers, which is reversible on removal.

Un-explained visual loss following silicone oil removal: results of the Pan American Collaborative Retina Study (PACORES) Group

PURPOSE

To report the incidence and clinical features of patients that experienced un-explained visual loss following silicone oil (SO) removal.

METHODS

Multicenter retrospective study of patients that underwent SO removal during 2000-2012. Visual loss of ≥2 lines was considered significant.

RESULTS

A total of 324 eyes of 324 patients underwent SO removal during the study period. Forty two (13%) eyes suffered a significant visual loss following SO removal. Twenty three (7.1%) of these eyes lost vision secondary to known causes. In the remaining 19 (5.9%) eyes, the loss of vision was not explained by any other pathology. Eleven of these 19 patients (57.9%) were male. The mean age of this group was 49.2 ± 16.4 years. Eyes that had an un-explained visual loss had a mean IOP while the eye was filled with SO of 19.6 ± 6.9 mm Hg. The length of time that the eye was filled with SO was 14.8 ± 4.4 months. In comparison, eyes that did not experience visual loss had a mean IOP of 14 ± 7.3 mm Hg (p < 0.0002) and a mean tamponade duration of 9.3 ± 10.9 months (p < 0.0001).

CONCLUSIONS

An un-explained visual loss after SO removal was observed in 5.9% of eyes. Factors associated with this phenomenon included a higher IOP and longer SO tamponade duration.

VITREORETINAL SURGERY WITH SILICONE OIL TAMPONADE IN PRIMARY UNCOMPLICATED RHEGMATOGENOUS RETINAL DETACHMENT: Clinical Outcomes and Complications

BACKGROUND

To determine the anatomical and functional outcomes and possible complications after pars plana vitrectomy (PPV) with silicone oil (SO) tamponade in primary uncomplicated rhegmatogenous retinal detachments.

METHODS

This is a prospective observational study. Overall, 62 consecutive patients who underwent surgical repair by PPV and SO injection for primary uncomplicated rhegmatogenous retinal detachment between January 01, 2006 and April 30, 2012 were followed. In general, PPV was chosen over scleral buckling when a significant cataract or a vitreous hemorrhage prevented adequate fundus visualization. Silicone oil was chosen over gas tamponade in patients living at 1,000 meters above the sea level, where SF6 or C3F8 tamponade could not be performed because of the risk of acute increase of intraocular pressure (IOP). One thousand centistokes SO was used in all eyes. At all visits, patients had a detailed ocular history and thorough bilateral evaluation, including best-corrected visual acuity, anterior segment examination, and IOP measurements by aplanation and fundus examination. Outcomes were assessed at 1 day, 1 week, 1 month, 3 months, 6 months, and every 6 months thereafter. Increased IOP was defined as an IOP of more than 21 mmHg.

RESULTS

Anatomical success rate, final best-corrected visual acuity, IOP elevation, cataract formation, and other complications were the main outcome measures. This study included 62 eyes of 62 patients (41 men and 21 women) that underwent retinal detachment repair by PPV and SO injection. The age at the time of intervention was 57.6 ± 10.5 years (mean ± standard deviation; range, 34-79 years). All patients were whites. Mean follow-up was 24.5 ± 17.3 months (range, 6-70 months). Anatomical success rate defined as retinal reattachment 6 months after SO removal was 93.5%. Final BCVA was improved in 55 eyes (88.7%), with a mean of 4 Snellen lines, unchanged in 5 (8.1%), and worse in 2 eyes (3.2%), with a mean of 3 Snellen lines. Mean duration of SO tamponade was 5.12 ± 2.37 months (range, 2-12 months). From the 30 eyes that were still phakic after vitrectomy, 24 eyes (80.0%) underwent cataract surgery within a period of 7.37 ± 3.00 months (range, 2-13 months). Thirty-five eyes (56.5%) had an increase in IOP during the follow-up period. Thirty-one patients had transient ocular hypertension requiring topical treatment during the immediate postoperative period (one month). Only 1 eye (2.9%) required filtrating drainage surgery for IOP control. No eyes developed optic neuropathy secondary to IOP elevation.

CONCLUSION

Pars plana vitrectomy with SO injection seems to be a safe and efficient surgical approach in the treatment of primary uncomplicated rhegmatogenous retinal detachment in patients living in high altitude (>1,000 m). Also, PPV and SO injection are associated with good anatomical and functional outcomes in our series. Reattachment rates are high, and rates of proliferative vitreoretinopathy are low. Cataract formation and elevated IOP represent frequent but successfully controlled complications.

INCIDENCE, RISK FACTORS, AND CLINICAL CHARACTERISTICS OF UNEXPLAINED VISUAL LOSS AFTER INTRAOCULAR SILICONE OIL FOR MACULA-ON RETINAL DETACHMENT

PURPOSE

To investigate the incidence, risk factors, and clinical characteristics of unexplained visual loss after macula-on rhegmatogenous retinal detachment (RRD).

METHODS

Retrospective cohort of patients with primary macula-on rhegmatogenous retinal detachment treated by vitrectomy with gas or silicone oil (SO) tamponade in 2011 and 2012. Outcome was unexplained visual loss (>2 Snellen lines) 2 months after the last vitrectomy.

RESULTS

Incidence of unexplained visual loss was 0.7% (1/151) in patients treated by gas and 29.7% (11/37) in patients treated by SO (P = 0.001). Visual loss occurred both during SO tamponade and after removal. Cases underwent optical coherence tomography, perimetry, microperimetry, fluorescein angiography, and visual evoked potentials. Patients with unexplained visual loss after SO tamponade showed a small scotoma within the central 2° on microperimetry. Duration of SO tamponade was the only statistically significant factor related to the incidence of unexplained visual loss (P = 0.001).

CONCLUSION

Incidence of SO-related visual loss was 30% with duration of tamponade as the only risk factor. This study is the first to apply microperimetry in these patients, which showed a distinct pattern of a small central scotoma. Therefore, microperimetry can be of great value in the diagnostic workup of patients with unexplained visual loss after vitrectomy.

Spectral domain optical coherence tomography findings in long-term silicone oil-related visual loss

PURPOSE

To investigate spectral domain optical coherence tomography findings in long-term silicone oil-related visual loss.

METHODS

Four symptomatic patients were reviewed 4 years to 9 years after vitrectomy with silicone oil tamponade for macula-on retinal detachment. Three lost vision with oil in situ, with one at the time of oil removal. Eleven control eyes with good vision were included. Patients underwent assessment of best-corrected visual acuity, contrast sensitivity, Farnsworth-Munsell 100 Hue testing, static perimetry, and spectral domain optical coherence tomography imaging of the macula and disk.

RESULTS

Long-term best-corrected visual acuity was significantly reduced in affected eyes (range, 0.44-1.02), as was contrast sensitivity (0.75-1.35) and color discrimination (Farnsworth-Munsell-100 Hue score, 151-390). Static perimetry showed a central scotoma in all affected eyes. Optical coherence tomography revealed microcystic macular changes in the inner nuclear layer of all affected eyes associated with severe loss of the papillofoveal retinal nerve fiber layer. In one patient, serial optical coherence tomography images showed development of microcystic macular changes 18 months after oil removal. Control eyes lacked these features, except two asymptomatic eyes that showed microcystic changes on optical coherence tomography with a corresponding paracentral scotoma.

CONCLUSION

We have demonstrated microcystic macular changes in the inner nuclear layer of affected eyes, as well as focal severe loss of the papillofoveal projection. These changes share significant morphologic features reported in multiple sclerosis-associated optic neuritis and Leber hereditary optic neuropathy.

The incidence of unexplained visual loss following removal of silicone oil

PURPOSE

To assess the incidence and clinical features of unexpected visual loss after removal of silicone oil (ROSO).

PATIENTS AND METHODS

A retrospective cross-sectional observational study of 421 consecutive eyes, which underwent silicone oil removal at one institution over a 2-year period.

RESULTS

Fourteen (3.3%) patients, (12 male, mean age of 53.1 years) suffered unexplained visual loss. In these eyes, the mean duration of silicone oil fill was 141 days (range 76-218). The mean loss of visual acuity was 3.7 (range 2-6) Snellen lines (SL) at 1 month, 3.5 (2-6) SL at 3 months and 2.91 (0-6) SL at 6 months. The change from preoperative visual acuity was statistically significant at all visits (P=0.02). Subgroup analysis of 20 fovea-sparing giant retinal tear (GRT) detachments, observed 10 (50%) cases of visual loss after ROSO. Electrodiagnostic testing suggested predominantly macular dysfunction, with optic nerve involvement in one case. Five of the 14 cases had variable recovery of vision.

CONCLUSION

There is a 3.3% overall incidence of visual loss following ROSO with a high rate (50%) observed in maculae on GRT detachments. Although recovery of visual acuity is seen in a minority of cases, visual loss after ROSO remains a serious and unexplained concern for vitreoretinal surgeons.

Unexpected and permanent central visual loss after removal of intraocular silicone oil

Here we report a case of unexplained sudden visual loss after removal of silicone oil for rhegmatogenous retinal detachment repair. A patient with visual loss in one eye after removal of silicone oil was investigated with best-corrected Snellen visual acuity assessment, fundus biomicroscopy, optical coherence tomography, color fundus photograph, fluorescein angiography, electrophysiologic examination, automated perimetry, and visual evoked potentials. Best-corrected Snellen visual acuity was 20/30 while the silicone oil was in place. Visual acuity dropped dramatically to 20/200 after silicone oil removal. No other complications associated with oil removal were noted. The retina remained attached. Visual evoked potentials revealed decreased amplitude due to a damaged optic nerve, while the earliest central visual field defects disappeared unexpectedly almost 2 years after the last surgical procedure. No other abnormalities were demonstrated. Vision loss is a possible complication of silicone oil and removal. This case was distinguished by the permanent decrease of visual acuity despite the unexplained and quite complete recovery of the foveal threshold with no other relevant visual field defects.

Neuronal complications of intravitreal silicone oil: an updated review

Silicone oil (SiO) has a well-established role as a long-term endotamponade agent in the management of complicated retinal detachments. Complications of intraocular SiO include keratopathy, glaucoma, cataract and subretinal migration of the oil droplets. SiO tamponade can also lead to a severe optic neuropathy caused by retrolaminar migration. Nevertheless, intracranial migration of the SiO through the optic nerve posterior to the lamina cribrosa to the optic chiasm and brain is uncommon. The mechanism is still under debate, but it has been suggested elevated intraocular pressure, macrophages or optic nerve head anatomical predispositions as potential explanations. Moreover, central scotoma may develop in eyes with SiO not only at the time of oil removal, but also during the period of tamponade. We performed a PubMed search of neuronal complications of silicone oil over a period of 25 years. This review summarizes our current understanding of the specific pathogenic mechanisms of intraocular SiO neuronal side effects, concluding that pre-existing glaucoma and optic nerve abnormalities are the main risk factors associated with this damage. In their absence, the risk of extraocular SiO penetration is so low that the use of SiO endotamponade in complex retinal detachment patients does not need to be modified. MRI images to assess extraocular SiO migration are only necessary in very few and special cases, such as patients with optic nerve abnormalities and glaucoma.

Giant retinal tears

A giant retinal tear (GRT) is a full-thickness neurosensory retinal break that extends circumferentially around the retina for three or more clock hours in the presence of a posteriorly detached vitreous. Its incidence in large population-based studies has been estimated as 1.5% of rhegmatogenous retinal detachments, with a significant male preponderance, and bilaterality in 12.8%. Most GRTs are idiopathic, with trauma, hereditary vitreoretinopathies and high myopia each being causative in decreasing frequency. The vast majority of GRTs are currently managed with a pars plana vitrectomy; the use of adjunctive circumferential scleral buckling is debated, but no studies have shown a clear anatomical or visual advantage with its use. Similarly, silicone oil tamponade does not influence long-term outcomes when compared with gas. Primary and final retinal reattachment rates are achieved in 88% and 95% of patients, respectively. Even when the retina remains attached, however, visual recovery may be limited. Furthermore, fellow eyes of patients with a GRT are at higher risk of developing retinal tears and retinal detachment. Prophylactic treatment under these circumstances may be considered but there is no firm evidence of its efficacy at the present time.

Intraocular pressure changes following 20G pars-plana vitrectomy

PURPOSE

To observe the excursions of short-term intraocular pressure (IOP) after 20-G pars-plana vitrectomy (ppV).

MATERIAL AND METHODS

In a prospective study, 851 patients (age: mean 63 ± 15 years) underwent unilateral ppV for various vitreoretinal diseases using different endotamponades [Balanced Salt Solution (BSS) 33.1%, Air 7.2%, SF(6) 33.6%, silicon oil 5000 cst 26.1%]. Intraocular pressure was measured in all patients before and at 3, 6, 24 and 48 hr after surgery. Survival analysis was performed to determine the cumulative hazard of IOP changes depending on endotamponade and time point after ppV (Log-Rang - Mantel Cox; p < 0.0001).

RESULTS

  At baseline, IOP ranged from 0 to 50 mmHg (mean IOP: 15.3 ± 5.3 mmHg). Mean IOP after surgery revealed a slight elevation (3 hr: 16.5 ± 11.0 mmHg; 6 hr 16.9 ± 9.8 mmHg; 24 hr 19.7 ± 8.0 mmHg; 48 hr 17.3 ± 6.2 mmHg; range: 0-64 mmHg). Silicon oil filling revealed highest mean values at already 3 hr after surgery (21.8 mmHg). Also, BSS filling showed a peak after 3 hr; however, mean values were lower. Equivalent high IOP values as for silicon oil tamponade were found for gas filling; however, maximal peak was reached after 24 hr but not after 3 hr post-treatment. The cumulative hazard in all patients to reach IOP ≥ 30 mmHg after 24 hr was 23.9%; (IOP ≥ 40 mmHg = 8.2%). Herein, oil filling revealed highest risk at all time points after surgery. The risk of suffering from IOP < 5 mmHg lasting longer than 6 hr was only 1.2% after 20 G vitrectomy.

CONCLUSION

Intraocular pressure measurements after ppV are important to prevent unintentional high IOP, especially within the early phase (3 hr post-treatment) in eyes with silicon oil filling. Gas filling leads to prolonged IOP increase (24 hr post-treatment). Long-lasting hypotony (≥ 6 hr) is very rare after 20G vitrectomy.

Visual loss after use of intraocular silicone oil associated with thinning of inner retinal layers

PURPOSE

To investigate the incidence and cause of severe visual loss following use and removal of intraocular silicone oil (SiO) after uncomplicated vitrectomy and SiO injection for primary rhegmatogenous retinal detachment (RRD).

METHODS

Consecutive case series of 216 patients operated with vitrectomy for primary RRD in 2004-2005. In 162 eyes, SiO (5500 centiStoke) had been used as intravitreal tamponade and in 54 eyes gas (perflouropropane, C(3) F(8) ) had been used. Following chart review, we identified 16 eyes in 16 patients (nine SiO eyes, seven gas eyes) with macula-on and documented visual acuity ≥6/12 before surgery, where SiO had been removed, cataract surgery performed and no re-detachment had occurred. Examinations included best-corrected visual acuity (BCVA) and high-definition optical coherence tomography (OCT) of the macular area.

RESULTS

Preoperative characteristics were identical between SiO and gas eyes. Postoperative BCVA was significantly worse in SiO eyes (>6/24) compared to gas eyes (>6/7.5), p = 0.005. Three of 9 (33%) SiO eyes had final BCVA ≤6/60 and 67% had final BCVA ≤6/12. No gas eyes had final BCVA <6/9. Macular OCT revealed thinning of inner retinal layers in SiO-operated eyes (5148 pixels) compared to gas-operated eyes (6897 pixels), p < 0.002. No other visually significant structural differences were found.

CONCLUSION

Severe visual loss after SiO use was observed in 1/3 of patients with otherwise good visual potential. The visual loss was associated with a significant reduction in inner retinal thickness indicating neuronal cell loss in the macular area as a possible explanation.

Clinical presentation of a mixed 23-gauge infusion and 20-gauge pars plana technique for active silicone oil removal

AIM

To present with a clinical case series of a mixed 23-gauge infusion and 20-gauge pars plana technique for 5,700-centipoise silicone oil removal (SOR), and to discuss its efficacy and safety.

METHODS

This is a retrospective, non-randomized controlled study. We performed SOR with 23-gauge infusion and 20-gauge active suction technique on 29 patients 29 eyes from April to October, 2011 (mixed group). During the surgeries, a 23-gauge sclerotomy was made for infusion and a 20-gauge sclerotomy was used for active silicone oil suction. Anterior segment optical coherence tomography (OCT) was applied for 23-gauge sclerotomy analysis 1 day post-operation. Traditional 20-gauge SOR was performed on another consecutive 29 patients 29 eyes, the control group (20G group).

RESULTS

There were 2 eyes (6.9%) in mixed group and 5 eyes (17.2%) in 20G group which had recurrent retinal detachment after surgery. Hopytony (IOP≤6mmHg) occurred in 8 eyes (27.6%) of mixed group and in 10 eyes (34.5%) of 20G group post-operation, but all of them recovered to the normal level finally. There were no statistical significant differences. Final visual acuity was significantly increased after surgery in both groups. Anterior segment OCT images were acquired from 13 eyes of mixed group, and all of them had a proper wound apposition. But local ciliary detachment was found in 9 eyes (69%). It was hard to define the OCT image of the sclerotomies and ciliary body because of the serious conjunctival hemorrhages and chemosis in 20G group.

CONCLUSION

This mixed technique is a convenient and effective way to remove high viscosity silicone oil. Compared with traditional 20-gauge SOR, it does not increase the risk of post-operative complications and has less conjunctival reactions.. Transient postoperative hypotony is common for this procedure and subclinical ciliochoroidal detachment is a probable cause.

Unanticipated vision loss after pars plana vitrectomy

Although advances in vitreoretinal surgical techniques and technology have helped to minimize the risks associated with surgical manipulation of the retina, retinal pigment epithelium, and optic nerve, unanticipated or unexplained visual loss still occurs. We review causes of vision loss encountered after pars plana vitrectomy, including retinal toxicities, vascular events, and optic neuropathies, and we suggest strategies to limit or prevent them.

Foveal light exposure is increased at the time of removal of silicone oil with the potential for phototoxicity

BACKGROUND

There is sudden and dramatic visual function deterioration in 1-10 % of eyes filled with silicone oil at the time of removal of silicon oil. Transmission of high-energy blue light is increased in eyes filled with silicone oil. We sought to identify if increased foveal light exposure is a potential factor in the pathophysiology of the visual loss at the time of removal of silicone oil.

METHODS

A graphic ray tracing computer program and laboratory models were used to determine the effect of the intraocular silicone oil bubble size on the foveal illuminance at the time of removal of silicone oil under direct microscope light. The graphic ray tracing computer program revealed a range of optical vignetting effects created by different sizes of silicone oil bubble within the vitreous cavity giving rise to an uneven macular illumination. The laboratory model was used to quantify the variation of illuminance at the foveal region with different sizes of silicone oil bubble with in the vitreous cavity at the time of removal of silicon oil under direct microscope light. To substantiate the hypothesis of the light toxicity during removal of silicone oil, The outcome of oil removal procedures performed under direct microscope illumination in compared to those performed under blocked illumination.

RESULTS

The computer program showed that the optical vignetting effect at the macula was dependent on the size of the intraocular silicone oil bubble. The laboratory eye model showed that the foveal illuminance followed a bell-shaped curve with 70 % greater illuminance demonstrated at with 50-60 % silicone oil fill. The clinical data identified five eyes with unexplained vision loss out of 114 eyes that had the procedure performed under direct microscope illumination compared to none out of 78 eyes that had the procedure under blocked illumination.

CONCLUSIONS

Foveal light exposure, and therefore the potential for phototoxicity, is transiently increased at the time of removal of silicone oil. This is due to uneven macular illumination resulting from the optical vignetting effect of different silicone oil bubble sizes. The increase in foveal light exposure may be significant when the procedure is performed under bright operating microscope light on already stressed photoreceptors of an eye filled with silicon oil. We advocate the use of precautions, such as central shadow filter on the operating microscope light source to reduce foveal light exposure and the risk of phototoxicity at the time of removal of silicone oil. The graphic ray tracing computer program used in this study shows promise in eye modeling for future studies.

Retinal stimuli can be restored after autologous transplant of retinal pigment epithelium and choroid in pigment epithelium tears

PURPOSE

To evaluate the functional and anatomical outcome of patients undergoing autologous transplant of retinal pigment epithelium (RPE) and choroid after RPE tear secondary to age-related macular degeneration (AMD).

METHODS

Data from nine eyes of nine patients were analysed retrospectively. Examinations included fluorescein and indocyanine green angiography, fundus autofluorescence imaging, optical coherence tomography, microperimetry and determination of visual acuity (far and reading ability). Data regarding intraoperative and postoperative complications were recorded. Mean follow-up time was 18 months (range 4 months to 5 years).

RESULTS

After surgery, far visual acuity improved or remained stable (±3 lines) in three of nine eyes and for the near visual acuity in three of nine eyes. Visual acuity decreased postoperatively at the last follow-up in four eyes mainly because of postoperative complications, i.e. retinal detachment due to proliferative vitreoretinopathy, retinal artery occlusion, pucker and fibrosis of the graft. In one case, retinal stimuli were restored over the scotoma as seen in microperimetry.

CONCLUSION

Autologous transplant of RPE and choroid is a therapy option for RPE tears. Retinal stimuli can be restored in selected cases. Numerous intra- and postoperative complications compromise the functional prognosis and outcome.

Long-term exposure of the rabbit eye to silicone oil causes optic nerve atrophy

A silicone oil endotamponade following vitrectomy has for decades been a standard method in human ophthalmology with a view to restoring a detached retina. However, severe functional deficiencies may remain after treatment. In adult rabbits, the injection of silicone oil into the eye-ball following vitrectomy resulted in a decrease of 89% in the number of myelinated optic nerve fibres after a survival time of 1 year (418,313+/-29,703 versus 45,620+/-23,905). Concomitantly, the cross-sectional area of the optic nerve was also reduced significantly (0.853+/-0.159 mm2 versus 0.355+/-0.107 mm2). The number of non-neuronal elements of the optic nerve remained virtually unchanged immediately behind the eye-ball and in the middle part of the nerve, whereas it increased significantly close to the optic chiasm (3040+/-433 versus 3888+/-403). Thus, destruction of the myelinated optic nerve fibres is likely to be responsible for the functional deficiencies observed after silicone oil implantation.

Immunopathology of intraocular silicone oil: enucleated eyes

AIMS

To characterise the distribution of silicone oil in ocular tissues in globes enucleated after complicated retinal detachment, and to document the distribution and nature of any associated inflammatory response.

METHOD

9 enucleated globes that had previously undergone retinal detachment surgery with silicone oil and 7 control globes that had undergone enucleation after retinal detachment surgery (n = 2) or ocular trauma (n = 5) were studied. Sections were histologically examined using light microscopy to document the distribution of silicone oil in ocular tissues. Immunohistochemical analysis was carried out using the ABC technique and a panel of monoclonal and polyclonal antibodies. Electron microscopy was undertaken to observe the penetration of silicone oil in the trabecular meshwork of the anterior chamber drainage angle.

RESULTS

Silicone oil was distributed throughout the globes-notably in the iris, ciliary body, retina, trabecular meshwork and epiretinal membranes. Focal areas of intraretinal silicone were associated with disorganised retinal architecture, retinectomy sites or subretinal oil. The distribution of macrophages was closely related to the distribution of silicone oil. T and B lymphocytes were not associated with silicone oil unless additional pathology was also present-for example, cyclitic membrane or uveitis. One of the nine eyes had silicone oil present in the optic nerve. In the control globes, the inflammatory response was mediated primarily by macrophages and T lymphocytes, and was less marked than that observed in the silicone oil globes.

CONCLUSION

This study shows that silicone oil may be sequestered in varied ocular tissues and is associated with localised inflammation mediated by macrophages.