Visual loss may be due to silicone oil tamponade effect rather than silicone oil removal

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.

Effect of silicone oil versus gas tamponade on macular layer microstructure after pars plana vitrectomy for macula on rhegmatogenous retinal detachment

PURPOSE

To analyze structural changes in the macular retinal layers and sub-foveal choroidal thickness (SFCT) in eyes after macula-on rhegmatogenous retinal detachment (RRD) repair by pars plana vitrectomy with either silicone oil (SO) or gas tamponade, and the effect of these changes on visual acuity.

PATIENTS AND METHODS

Retrospective study which included 26 eyes in the SO Group and 32 in the Gas Group. Optical coherence tomography (OCT) scans of the affected eyes were obtained before surgery, and 3 months after PPV in the Gas Group, and during silicone oil in situ and 3 months after SO removal, in the SO Group. Qualitative assessment of photoreceptor layer and foveal contour, along with quantitative assessment of macular retinal thickness and SFCT was performed. Postoperative OCT macular microstructural changes were recorded and correlated to corrected distance visual acuity (CDVA). Intraocular pressure (IOP) was measured preoperative and at 3 months post operative.

RESULTS

There was a 2-line loss (from 20/28 preoperatively to 20/40 at final follow-up) of CDVA in the SO Group (p=0.051), while there was no statistically significant change in CDVA in the Gas Group (p=0.786). There was no significant correlation between CDVA loss and duration of silicon tamponade (r=-0.031, p=0.893). There was a statistically significant increase in IOP from its baseline to final follow-up of 0.7 mmHg in the SO Group (p=0.023) while there was no statistically significant change in IOP in the Gas Group. During silicone oil tamponade, there was approximately 11% and 5% of retinal and sub-foveal choroidal thinning respectively, which was moderately resolved following silicone oil removal. 20% (5/24) of eyes in the SO Group had qualitative flattening of foveal contour during SO tamponade that resolved after SO removal.

CONCLUSION

Thinning of the macula was noticed after macula-on RRD repair with SO tamponade. Such thinning was only partially reversible after the removal of SO.

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.

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.

Vision loss under silicone oil tamponade

PURPOSE

We aimed to investigate frequency, time course and pathophysiology of vision loss in eyes with macula-on rhegmatogenous retinal detachment operated with vitrectomy and silicone oil tamponade.

PATIENTS AND METHODS

Fifteen eyes of 15 patients who had been operated with 5,000 centistoke silicone oil between 2006 and 2014 were included in a retrospective case series. Examinations included logMAR best corrected visual acuity (BCVA), visual field testing (VF), spectral domain optical coherence tomography (OCT), electrophysiology, and fluorescein angiography.

RESULTS

Vision loss was seen in eight (53 %) eyes of 15 patients with symptomatic central scotoma, which was confirmed by VF (5/6). Preoperative median BCVA of these patients was 0.15 (0.5 to 0), prior to oil removal 0.7 (1.0 to 0.5), and 6 weeks post oil removal 1.0 (1.5 to 0.2). BCVA recovered in five patients to a median of 0.15 (0.5 to 0.1), and it remained 1.0 in three (20 %) out of 15 eyes. OCT revealed significant thinning of the foveal and parafoveal combined nerve fiber, ganglion cell and inner plexiform layers in affected eyes (mean 58.3 μm +/-13, horizontal scan through fovea, 500 μm radius) compared to their healthy fellow eyes (mean 84.5 μm +/-12.3; p < 0.01, n = 6 patients, 12 eyes) and compared to eyes with no vision loss under silicone oil.

CONCLUSIONS

We find persisting vision loss in three out of 15 patients treated for macula-on rhegmatogenous retinal detachment with silicone oil tamponade. Thinning of inner retinal layers possibly evoked by silicone oil tamponade might be a pathophysiological explanation for vision loss in these patients.

Surgical and visual outcome following 20-gauge vitrectomy in proliferative diabetic retinopathy over a 10-year period, evidence for change in practice

INTRODUCTION

The study reports 10-year anatomical and visual outcome in patients who underwent pars plana vitrectomy (PPV) for complications due to proliferative diabetic retinopathy (PDR).

METHODS

Retrospective analysis of patients undergoing 20 G PPV from January 1999 to May 2010 for tractional retinal detachment (TRD) and non-clearing vitreous hemorrhage (NCVH) secondary to PDR recorded prospectively on an electronic patient record. The primary aim was to study anatomical success and eyes with visual acuity (VA) of ≤ 0.3 logMAR at last follow-up.

RESULTS

There were 346 eyes of 249 patients with mean age of 55.63 years and follow-up of 1.44 years. In all, 95.3% of eyes had a flat retina at final follow-up. Overall 136/346 (39.4%) eyes had final VA of logMAR ≤ 0.3 (Snellen 6/12) and 129 (37.3%) had logMAR ≥ 1.0 (Snellen 6/60). In all, 50/181 (27.6%) eyes with TRD and 84/165 (50.9%) with NCVH achieved final VA of ≤ 0.3 logMAR (Snellen 6/12). A total of 218 (63.1%) showed ≥ 0.3 logMAR improvement from baseline to last follow-up. Both preoperative VA and final postoperative (post-op) VA (P<0.001) improved significantly with each year from 1999 to 2010. The commonest peroperative complication was iatrogenic retinal tear formation (28.4%). This was a risk factor for the development of post-op retinal detachment, odds ratio: 3.90 (95% confidence interval: 1.91-7.97, P = 0.0002). Silicone oil was used in 5.2% of patients at the primary procedure. In all, 9.2% required removal of non clearing post vitrectomy hemorrhage.

CONCLUSIONS

Outcomes from vitreoretinal surgery for complications of diabetic retinopathy have improved. In addition, the visual outcome after diabetic vitrectomy steadily improved over the 10-year period, which may in part be due to the move to operate on patients with better vision.