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

Vision loss associated with silicone oil endotamponade in vitreoretinal surgery - a review

PURPOSE

To clarify the definition, prevalence and classification of different types of unexplained vision loss associated with silicone oil (SO) endotamponades (SO in situ (SOIS) or after removal of SO (ROSO)) in vitreoretinal surgery and identifying the most specific clinical findings and suggesting possible causes.

METHODS

Review of the literature regarding randomized clinical trials (RCTs), retrospective case-control, cohort studies and case series evaluating the risk of using SO, published in English between 1994 and 2023, conducting a computer-based search of the following databases: PubMed, Web of Science, Scopus and Embase. The search was supplemented using the Medline option 'Related Articles' and consulting review articles on the topic.

RESULTS

Findings from reported clinical examinations in SOIS and ROSO are analyzed and finally different theories regarding the underlying pathophysiology are described. From the clinical point of view, findings have been found in OCT, OCTA, microperimetry and electrophysiological studies. Other clearly identifiable causes of vision loss related to the use of SO are listed and commented as differential diagnosis. Finally, the different physiopathological theories of the two types of causes of unexplained vision have been analyzed.

CONCLUSION

Unexpected vision loss under or after SO tamponade (SOIS and ROSO) is a significant concern which is probably underestimated because it is not a clearly defined and known entity. The most frequently described changes were in the ganglion cell complex but this unexpected vision loss remains a serious and unexplained concern for vitreoretinal surgeons and should be identified by clinicians, addressed by manufacturers and reported to Health Authorities as a serious incident according to the new regulation.

Management of macula-on giant retinal tear detachments- outcome of pars-plana-vitrectomy with silicone oil versus gas tamponade

BACKGROUND

To compare the outcome of eyes with a macula-on giant retinal tear (GRT) detachment treated with pars-plana-vitrectomy (PPV) depending on the used endotamponade.

METHODS

All consecutive cases with a macula-on GRT-associated rhegmatogenous retinal detachment (RRD) managed with PPV between 2007 and 2022 were retrospectively assessed depending on the selected endotamponade. By reviewing medical charts and surgical protocols the pre- and intraoperative parameters were analysed in detail. The number of vitreoretinal (VR) procedures needed for reattachment, the redetachment rate and the functional outcome were evaluated. Eyes treated with primary silicone oil (SO) tamponade were compared to eyes with primary gas tamponade. Cases with pre-existing conditions affecting outcome e.g. macula-off situation, history of trauma, status after complicated cataract surgery, former VR surgery or proliferative vitreoretinopathy grade C or higher were excluded.

RESULTS

Overall, 51 eyes of 45 patients with a macula-on GRT detachment were treated with PPV and SO (n = 32; 63%) or gas (n = 19; 37%) endotamponade in the observed period. Eyes with primary SO tamponade underwent on average 2.3 (SD 0.8) VR procedures and had a redetachment rate of 13% (n = 4). Eyes with gas tamponade showed a higher redetachment rate of 32% (n = 6) with a mean number of 1.6 (SD 1.0) PPV procedures. Postoperative best-corrected visual acuity (BCVA) was significantly better in eyes with primary gas tamponade (mean logMAR BCVA 0.32; SD 0.30) compared to eyes with SO (mean logMAR BCVA 0.60; SD 0.42; p = 0.008).

CONCLUSIONS

Surgical management of GRT-associated RRDs is complex. In clinical routine often SO is used as endotamponade. Because of known disadvantages (second procedure necessary for SO removal, unexplained SO-related visual loss, secondary glaucoma, SO emulsification) some VR surgeons prefer a gas tamponade. In our cohort, eyes with a gas compared to SO tamponade showed higher redetachment rates. However, the final postoperative BCVA was significantly better in eyes with gas compared to SO tamponade.

TRIAL REGISTRATION

The trial protocol was approved by the local ethics committee on 25th of November 2022 (Ethikkommission der Universität Regensburg, Votum 22-3166-104).

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.

Unexplained visual loss in retinal detachment repair: comparing gas, silicone oil and heavy silicone oil by multivariable regression

PURPOSE

To measure the proportion of unexplained and all causes of visual loss following primary rhegmatogenous-retinal-detachment (RRD) repair, comparing gas tamponade (SF₆, C₂F₆, C₃F₈), silicone oil (SO, 1000cs and 5000cs) and heavy silicone oil (Densiron).

METHODS

Retrospective, continuous, comparative study from 01/1/2017-31/5/2021. All primary RRDs were included after successful removal of SO and Densiron. Primary failures were excluded. Visual loss was defined as reduction of ≥0.30 logMAR units. Multivariable binary-logistic and linear regression models to compare tamponade, and all cases of unexplained visual loss and logMAR gain were performed. Covariates included age, ocular co-morbidities, pre-op vision, macula-status, high-myopia, giant-retinal-tear (GRT), perfluorocarbon-use, combined buckle/PPV, PVR-C, retinectomy, tamponade agent and post-operative lens status.

RESULTS

Of 1,012 primary RRDs, we found an incidence of unexplained visual loss in 15/1012 (1.5%, SF₆:1/341[0.3%], C₂F₆:4/338[1.2%], C₃F₈:2/239[0.8%], Densiron:0/33[0.0%], SO-1000cs:5/43[11.6%] and SO-5000cs:3/18[16.7%]), and visual loss of all causes in 57/1012 (5.6%, SF₆:13/341[3.8%], C₂F₆:14/338[4.1%], C₃F₈:15/239[6.3%], Densiron:2/33[6.1%], SO-1000cs:9/43[20.9%] and SO-5000cs:4/18[22.2%]). On multivariable binary-logistic regression, we report that macula-on RRD (Odds-Ratio[OR]5.7,95% Confidence-interval[CI]1.2-28.2, p=0.032), GRT (OR35.0,CI 2.0-617.3, p=0.015), combined buckle/PPV (OR37.7,CI 2.0-711.4, p=0.015), SO1000cs (OR86.6,CI 5.6-1,348.0), p=0.001) and 5000cs (OR37.2,CI 1.3-1,101.5, p=0.036) (Reference-tamponade:SF₆) were associated with unexplained visual loss. Duration of oil tamponade was not linked to increase in unexplained visual loss (p=0.569).

CONCLUSIONS

Correlation between SO in detachment repairs and unexplained visual loss has been established, however incidence with HSO has not been compared to other agents. This study demonstrates that although SO was linked with risk-adjusted increased unexplained visual loss relative to gas tamponade, no such association was found for Densiron, on multivariable analysis.

Unexplained visual loss after primary pars-plana-vitrectomy with silicone oil tamponade in fovea-sparing retinal detachment

BACKGROUND

To investigate the incidence and clinical characteristics of unexplained visual loss in patients with fovea-sparing rhegmatogenous retinal detachment (RRD) during or after silicone oil (SO) tamponade.

METHODS

The medical charts of all patients with macula-on RRDs, who underwent pars-plana-vitrectomy (ppV) with SO tamponade were retrospectively assessed regarding unexplained visual loss (UVL) of ≥ 3 Snellen lines and alterations on optical coherence tomography (OCT) during or after SO tamponade. The clinical data analysed included visual acuity, surgical parameters, OCT images, duration of SO tamponade and the time point of visual decline. Cases with re-detachment or secondary causes of visual loss such as SO emulsification, epiretinal membranes or macular edema were excluded.

RESULTS

Over a 15-year-period, 22 cases with macula-on RRD, which had primarily been treated with ppV and SO tamponade, met the inclusion criteria. In most eyes (n = 20; 91%), the RRD was caused by a giant retinal tear (GRT). In 11 of these 22 cases (50%), best-corrected visual acuity (BCVA) had dropped by at least 3 lines for no apparent reason. In these 11 cases, mean preoperative logMAR BCVA was 0.2 (SD 0.13; range 0-0.5), equal to Snellen's VA of 0.63, and mean postoperative logMAR BCVA 1.0 (SD 0.24; range 0.5-1.3), equal to Snellen's VA of 0.10. Visual decline occurred about 12 weeks postoperatively (SD 6.2; range 3-20 ) and comprised 8 lines (SD 2.3; range -11 to -4). SO was removed on average 139 (SD 50.0; range 88-271) days after the first ppV. In 9 cases visual decline occurred while the SO was in-situ. In 2 patients, BCVA decline was noted 2 weeks after SO removal. In all eyes, preoperative central foveal thickness (CFT) was 254 μm (SD 24.2), which decreased to 224 μm (SD 29.6) during SO tamponade and increased to 247 μm (SD 29.2) after SO removal, irrespective of the presence of UVL. The mean follow-up time was 20 months (SD 30.6) after SO removal.

CONCLUSION

UVL after SO tamponade for macula-on RRD is more frequent than expected. The incidence in our case series was 50%. The mechanism of this phenomenon is still unknown. In general, vitreoretinal surgeons should thoroughly question the need for SO tamponade, inform their patients of possible UVL and remove SO as early as possible.

TRIAL REGISTRATION

The study was approved by the local ethics committee on 6th of May 2022 (Ethikkommission der Universität Regensburg, Votum 22-2925-104) and was conducted in accordance with the ethical standards of the Declaration of Helsinki.

Silicone oil tamponade in surgical treatment of rhegmatogenous retinal detachment

The article presents a literature review regarding the use of silicone oil tamponade (ST) in rhegmatogenous retinal detachment (RRD) treatment. Vitrectomy, which produces a stable anatomical result in most patients, is currently recognized as one of the main methods of treating RRD. In complicated retinal detachments, vitrectomy is followed by ST tamponade of the vitreous cavity (VC). Despite the many benefits of ST, it carries the risk of a number of complications arising at different times after surgery. The duration of ST presence in the vitreous cavity during RRD treatment may vary substantially. The review presents ST complications, including an unexpected and hard to explain vision deterioration after silicone oil removal, and the correlation between the complications and the duration of ST presence in the vitreous cavity.

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.

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.

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.

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.

Removal of sticky silicone oil adhered to the retinal surface: comparison of methodological safety and effectiveness

PURPOSE

To compare safety and effectiveness among methods to remove sticky silicone oil bubbles adhered to the retinal surface.

METHODS

This retrospective nonrandomised case series included 14 eyes of 14 patients who had sticky silicone oil residue during silicone oil removal surgery. For small sticky silicone oil bubbles (< 2-disc diameter), aspiration was performed with a 23-gauge vitreous cutter. Residual tiny oil bubbles were then removed with a silicone-tipped flute needle or internal limiting membrane (ILM) peeling. For large sticky silicone oil bubbles (≥ 2-disc diameter) that could not be removed with a 23-gauge vitreous cutter, we devised a more efficient active removal method involving a modified 22-gauge venous indwelling cannula device.

RESULTS

The mean preoperative best-corrected visual acuity (BCVA; logarithm of the minimum angle of resolution [logMAR]) significantly improved from 1.28 ± 0.63 logMAR to 0.77 ± 0.58 logMAR (p = 0.014). The postoperative BCVA and improvement in BCVA were significantly better in the ILM peeling group than in the non-ILM peeling group (p = 0.004 and p = 0.045, respectively). Postoperative complications included residual sticky silicone oil bubbles in seven eyes without ILM peeling (50.0%), retinal neuroepithelial layer damage in two eyes (14.3%), and temporary hypotony in five eyes (35.7%).

CONCLUSION

Various methods can safely and efficiently remove sticky silicone oil bubbles adhered to the retinal surface. A 22-gauge venous indwelling cannula enabled simple and safe removal of large sticky silicone oil bubbles, while small residual sticky silicone oil bubbles could be completely removed by ILM peeling.

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.

LABORATORY EVALUATION OF INTRAOCULAR SILICONE OIL REMOVED AFTER 23 YEARS IN SITU

PURPOSE

To report the clinicopathologic correlation and biochemical analysis of silicone oil removed after 23 years in an eye.

METHODS

A 63-years-old man with a history of HIV/AIDS and cytomegalovirus retinitis, status post retinal detachment repair with silicone oil at the age of 39 years, presented with several weeks of worse vision. He was found to have a shallow fovea-off tractional retinal detachment. After the silicone oil was removed during retinal detachment repair, it was analyzed by Fourier-transform infrared spectroscopy and gas chromatography with mass spectrometry.

RESULTS

In addition to cyclic and linear silicone oil, cholesterol was found in the removed silicone oil, which was not present in unused silicone oil samples. No other chemical alterations were identified in the extracted silicone oil.

CONCLUSION

Silicone oil left inside an eye over an extended period may extract lipophilic substances from adjacent tissue, with possible pathophysiologic effects. However, no other major potentially toxic substance was identified from the long-standing silicone oil sample, suggesting relative chemical stability of the tamponade agent over time.

Peripapillary Vessel Density in Eyes with Rhegmatogenous Retinal Detachment after Pars Plana Vitrectomy

Purpose

To investigate the vascular density of the optic nerve head (ONH) and macula using optical coherence tomography angiography (OCTA) in patients undergoing vitrectomy for rhegmatogenous retinal detachment (RRD) and to evaluate associations with visual outcomes.

Methods

Patients with RRD, successfully treated with a pars plana vitrectomy (PPV) and a minimum three-month follow-up were included in this study. The vessel density (VD) of the ONH and peripapillary regions, foveal avascular zone (FAZ), foveal flow density (FFD), and parafoveal flow density (PFD) were evaluated using OCTA and compared to the fellow eye. Multivariate linear regression analysis was performed to determine correlations with visual outcomes.

Results

Thirty-one patients with macula-off RRD were included in the study. Compared with the fellow eyes, eyes after RRD surgery had a lower peripapillary VD (P < 0.01). No significant difference in superficial and deep FFD, PFD, and FAZ area was found compared to the fellow eyes. Postoperative peripapillary VD and baseline BCVA were significantly associated with BCVA three months after PPV (P < 0.05).

Conclusion

Rhegmatogenous retinal detachment eyes successfully treated with PPV had lower peripapillary vessel density than fellow healthy eyes. Postoperative BCVA was related to postoperative peripapillary VD.

Topical Review: Causes of Refractive Error After Silicone-oil Removal Combined with Cataract Surgery

SIGNIFICANCE

This review summarizes the main factors of refractive error after silicone oil removal combined with cataract surgery.The post-operative refractive results of silicone oil removal combined with cataract surgery are closely related to the patient's future vision quality. This report summarizes the factors that influence the difference between the actual post-operative refractive power and the pre-operatively predicted refractive power after silicone oil removal combined with cataract surgery, including axial length, anterior chamber depth, silicone oil, commonly used tools for measuring intraocular lens power, and intraocular lens power calculation formulas, among others. The aim of the report is to assist clinical and scientific research on the elimination of refractive error after silicone oil removal combined with cataract surgery.

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.

Comparison of Long-Term Automated Retinal Layer Segmentation Analysis of the Macula between Silicone Oil and Gas Tamponade after Vitrectomy for Rhegmatogenous Retinal Detachment

PURPOSE

To identify long-term changes in individual retinal layer thickness using automated retinal layer segmentation analysis on high-resolution spectral-domain optical coherence tomography (SD-OCT) scans of eyes with macula-off rhegmatogenous retinal detachment (RRD) treated with vitreoretinal surgery (VRS) and gas or silicone oil tamponade and having single-operation success.

METHODS

A total of 58 patients operated on by VRS for RRD and followed up for 12 months were imaged by SD-OCT. The patients with retinal diseases such as an epiretinal membrane or cystic macular edema in the operated and fellow eyes were excluded. The thicknesses of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptor layer, and retinal pigment epithelium were compared to those of the fellow eyes after the 12-month follow-up. Thickness changes in individual layers were quantitatively analyzed in the operated and fellow eyes and correlated with the type of tamponade used in the surgery.

RESULTS

Spectralis OCT automated segmentation software was used for the retinal layer analysis. There were 22 females and 36 males. Their mean age was 60.7 ± 11.2 years. The mean central macular thickness was 214.3 ± 29.5 µm in the operated and 229.7 ± 21.7 µm in the fellow eyes (p = 0.008). There was a statistically significant difference between the operated and the healthy fellow eyes in the following layers: the RNFL (p = 0.017), GCL (p = 0.02), INL (p = 0.005), and ONL (p = 0.008) in the central foveal area; the RNFL (p < 0.001), INL (p = 0.017), and ONL (p = 0.022) in the perifoveal ring; and the RNFL (p < 0.001), IPL (p = 0.042), INL (p = 0.001), and OPL (p = 0.001) in the peripheral ring. The logMAR best corrected visual acuities were 2.51 ± 0.68 and 2.69 ± 0.62 at baseline and 0.60 ± 0.38 and 0.50 ± 0.38 at month 12 in the silicone oil tamponade (n = 28) and the gas tamponade (n = 30) group (p = 0.52 and p = 0.21, respectively). The foveal GCL, OPL, and ONL and the perifoveal GCL and IPL were statistically significantly thinner in the silicone oil tamponade group (p = 0.01, p = 0.046, p = 0.024, p = 0.006, and p = 0.011, respectively).

CONCLUSIONS

Significant changes were observed in the retinal layers after VRS for RRD. Individual retinal layers seem to be affected 1 year after VRS for RRD. The type of tamponade can influence the thickness of the retinal layers. The thickness of the retinal layers was significantly preserved in eyes treated with gas tamponade when compared to those treated with silicone oil tamponade in the long term. Further studies are needed to validate our results.

Comparison Between Silicone Oil and Gas in Tamponading Giant Retinal Breaks

Purpose

The purpose of this study is to compare anatomical and visual outcomes after using silicone oil (SO) or C₃F₈ gas as tamponades after pars plana vitrectomy (PPV) for retinal detachment (RD) associated with giant retinal tears (GRTs).

Methods

A retrospective chart review was conducted for cases that underwent PPV for GRT-associated RD. We excluded eyes that had prior vitreoretinal surgery, a history of ocular trauma or worse than grade B proliferative vitreoretinopathy (PVR). Baseline demographic and ocular characteristics, surgical details and postoperative anatomical and visual outcomes were recorded and statistically analyzed.

Results

We included 88 eyes; 48 eyes had C₃F₈ gas and 40 eyes had SO as a tamponading agent. Mean age was 39 years. All eyes underwent 23G PPV with no adjuvant scleral buckling and phacovitrectomy was performed for all phakic eyes. Final retinal reattachment was achieved in 86 eyes (97.7%). One eye from each group had recurrent RD. Postoperative vision was significantly better in the gas group (p= 0.008). Prolonged increase of IOP developed in 6 eyes in the SO group and 5 eyes in the gas group. Prolonged uveitis developed in 4 eyes in the gas group and 6 eyes in the oil group (P= 0.04). Epiretinal membranes (ERM) developed in 10 eyes in the gas group and 9 eyes in the oil group. We found no significant difference between both groups regarding postoperative glaucoma or ERM formation.

Conclusion

Both agents achieved similar favorable anatomical outcomes in a series of eyes with fresh GRT-associated RD and low-grade PVR, with better visual outcome and less frequent uveitis associated with the use of gas tamponade.

Silicone Oil Tamponade in Rhegmatogenous Retinal Detachment: Functional and Morphological Results

Purpose: To evaluate the functional and morphological outcomes of patients with SO tamponade due to primary rhegmatogenous retinal detachment (primRD) and recurrent rhegmatogenous detachment (recRD).Methods: Seventy-five eyes were enrolled in this prospective study between January 2009 and December 2016. Patients with primRD and recRD were evaluated in a complete ophthalmic examination including best-corrected visual acuity (BCVA) and OCT before and after silicone oil removal (SOR).Results: The primRD group comprised 35 eyes and the recRD group 40 eyes with a duration of SO tamponade of 9 ± 4/12 ± 11 months in the primRD/recRD groups (p = .088). The preoperative OCT revealed a high rate of morphological changes such as ERM (primRD: 24%; recRD: 69%) and CME (primRD: 10%; recRD: 55%) in the recRD compared with the primRD group (ERM: p = .18; CME: p = .04). No such difference was observed postoperatively. Disruption of the ellipsoid zone (EZ) was similar in both groups (primRD: 52%; recRD: 72%) before SOR and was restored in 66%/58% (primRD/recRD) after SOR. No difference was found regarding pre- and postoperative VA (0.91 ± 0.54/0.90 ± 0.54logMAR primRD/recRD preoperative; 0.76 ± 0.56/0.71 ± 0.53logMAR primRD/recRD at the last follow-up; p = .96/p = .70). EZ integrity (0.43 ± 0.31logMAR) was associated with better functional results than an interrupted EZ (0.86 ± 0.43logMAR; p < .001). A significant positive correlation of the duration of SO tamponade and the final VA was found in the primRD (r = 0.396, p = .02) whereas none in the recRD group (r = 0.196; p = .31).Conclusion: Morphological changes including ERM and CME were more pronounced in the recRD group, but only before SOR. Interestingly, the pre- and postoperative BCVA were similar in both groups with EZ integrity being a factor of good functional outcome. The duration of SO tamponade had a statistically significant negative impact on the postoperative VA in the primary detachments.

Silicone oil removal: post-operative complications

PURPOSE

To describe the characteristics, outcomes and complications of eyes after silicone oil removal.

METHODS

Retrospective case series of eyes that underwent oil removal between 2012 and 2016 at The Institute of Ophthalmology and Visual Science. Visual acuity (VA), intraocular pressure (IOP) and rates of retinal re-detachment, hypotony, ocular hypertension, corneal decompensation, cystoid macular edema (CME) and cataract progression were evaluated.

RESULTS

Totally, 101 eyes of 99 patients (65% male, average age 47.2 years) were identified. Oil tamponade had been used for retinal detachment (RD) repair in all eyes; 15 eyes had also undergone an open globe repair previously. The most common vitreous substitutes used after oil removal were balanced salt solution (BSS) and air in 90% of eyes. The average time of oil tamponade before removal was 9.46 months. The average logMAR VA before oil removal was 1.7 which improved to an average of 1.4 post-operatively. The average IOP pre-operatively was 16.1 mm Hg, which decreased to an average of 14.8 mm Hg post-operatively. Complications after oil removal, included retinal re-detachment (6.9%), hypotony (7.9%), ocular hypertension (12.9%), corneal decompensation (9.9%), CME (2%) and cataract progression (68%).

CONCLUSION

This study showed an overall improvement in VA and decrease in IOP after oil removal. Cataract progression was the most common complication.

Silicone oil-associated retinal light exposure under a surgical microscope

PURPOSE

Based on the hypothesis that silicone oil (SO) with a higher refractive index than water induces unexpected vignetting effects during surgeries, we aimed to investigate the relationship between the volume of SO and light intensity using a surgical microscope.

METHODS

Using a light-sensitive paper and model eye filled with varying volumes (0%, 50%, 62.5%, 75%, 87.5% and 100%) of SO, the light intensity of intraocular lens (IOL) with various refractive powers (0, 10 and 20 dioptres) illuminated by a surgical microscope was measured.

RESULTS

Light exposure density with 1.0% coaxial and oblique light was approximately 22-fold higher than that with 0.1% coaxial and oblique light. Further, it was approximately 34-fold higher in eyes with +20 D IOL than in those with no IOL. The density in eyes with 75% SO was the highest among all groups followed by that with 0% SO. Light exposure densities in the eyes with 75% and 0% SO were significantly higher than those with other volumes of SO. In SO-filled eyes, a microscope set with only an oblique light and a filter successfully reduced light exposure.

CONCLUSION

Silicone oil-related vision loss (SORVL) during SO removal surgeries might be due to increased light exposure on the macular retina caused by the SO-associated vignetting effect. SORVL could be prevented by placing a filter in the microscope during SO removal surgeries.

Biological Characteristics of Subsilicone Oil Fluid and Differences With Other Ocular Humors

Purpose

Subsilicone oil fluid (SOF) in eyes with silicone oil (SO) endotamponade possibly has a role in complications (e.g., vision loss); thus, we aimed to examine inflammatory cytokine and electrolyte levels and retinal glial cell viability in SOF.

Methods

We measured major inflammatory cytokine levels and electrolytes in SOF and compared them with those in vitreous fluid (VF) and anterior chamber fluid (ACF). We analyzed the correlation between inflammatory cytokines and retinal thickness in SO-filled eyes. Further, we measured the MIO-M1 cell viability in medium with SOF and compared it with that containing VF.

Results

We collected and examined 57 SOF, 22 ACF, and 21 VF samples from eyes with PVR, PDR, RD, and MH. Interleukin (IL)-8 and monocyte chemoattractant protein (MCP)-1 levels in SOF were significantly higher than those in ACF. There was no significant difference for all cytokines between SOF and VF. Retinal thickness changes during SO endotamponade were not correlated with the presence of any inflammatory cytokines. Levels of ferrous iron, but not of potassium, showed a significant decrease in SOF compared with VF. The WST-1 assay showed that SOF-added medium induced higher MIO-M1 cell viability than VF-added medium.

Conclusions

We found no significant correlation between the change in the retinal thickness and cytokine levels, but SOF contains higher concentrations of cytokines and lower concentrations of ferrous iron and can be biologically distinguished from ACF and VF.

Translational Relevance

Novel knowledge of inflammatory cytokine levels and electrolytes in SOF provides better understanding of pathology of SO-filled eyes.

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.