Perte brutale d’acuité visuelle post-ablation de silicone : à propos de trois patients traités pour déchirure géante

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.

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.

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.

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.

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-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.

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.

Subfoveal choroidal thickness change following pars plana vitrectomy with silicone oil endotamponade for rhegmatogenous retinal detachment

PURPOSE

To report changes in subfoveal choroidal thickness (SFCT) using spectral-domain optical coherence tomography following pars plana vitrectomy (PPV) with silicone oil (SiO) endotamponade injection and subsequent removal.

METHODS

In this prospective study, 24 eyes of 24 patients with macula-off rhegmatogenous retinal detachment (RD) were included. These patients underwent PPV with SiO injection removal. SFCT measurements were taken 2 weeks and 3 months after PPV and SiO injection and 1 month after SiO removal. The contralateral eyes served as controls.

RESULTS

Mean SFCT values of the operated eyes were 294.1 ± 70.5 µm and 282.9 ± 80.6 µm 2 weeks and 3 months after PPV and 264.2 ± 63.3 µm 1 month after SiO removal. There was no significant change in SFCT between first and second measurements (p = 0.96). SFCT decrease was statistically significant when first and last measurements were compared (p = 0.03). SFCT percent change was correlated with duration of SiO in the eye and was not correlated with amount of endolaser photocoagulation performed during surgery. SFCT values of the fellow eyes were 317.1 ± 84.8 µm, 313.7 ± 79.8 µm and 306.1 ± 69.1 µm, at 2 weeks and 3 months after PPV and 1 month after SiO removal, respectively. There was no significant difference between the measurements of the control eyes taken at different time intervals (p = 0.430, p = 0.085, respectively).

CONCLUSION

SFCT seems to decrease after the removal of the SiO which indicates that choroidal parameters should be taken into account during or after surgery for rhegmatogenous RD.

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.

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.

Electrolyte composition of retro-oil fluid and silicone oil-related visual loss

PURPOSE

Up to one-third of patients with intra-ocular silicone oil (SO) tamponade for complex macula-on retinal detachment may experience an unexplained visual loss during or after SO tamponade. Although the underlying mechanism is unknown, previous studies suggested that accumulation of retinal potassium could be involved. Hence, this study tested the hypothesis that intra-ocular potassium levels are elevated during SO tamponade.

METHODS

A prospective cohort study was carried out from 13 October 2013 through 5 March 2015. Potassium, sodium, magnesium, chloride, calcium, lactate dehydrogenase (LDH) and glucose levels were measured in retro-oil fluid and paired serum from 16 patients undergoing oil removal, including two patients with SO-related visual loss (SORVL). Vitreous humour and paired serum from 27 patients with macular hole (n = 19) or floaters (n = 8) served as controls.

RESULTS

Median potassium levels in retro-oil fluid and vitreous humour were similar. Magnesium and chloride levels were lower in retro-oil fluid compared with vitreous humour (p < 0.01) and LDH levels were elevated in retro-oil fluid (p < 0.0001). One of the two patients with SORVL revealed abnormal high potassium and magnesium levels. The other patient had normal levels.

CONCLUSION

Potassium levels are not increased in retro-oil fluid during SO tamponade, making the 'potassium accumulation' hypothesis unlikely. The disturbance in magnesium concentration during SO tamponade warrants further investigation.

Macular Effects of Silicone Oil Tamponade: Optical Coherence Tomography Findings During and After Silicone Oil Removal

OBJECTIVE

To investigate retinal morphologic changes during silicone oil tamponade and after its removal using spectral domain OCT (SD-OCT) imaging.

MATERIALS AND METHODS

Retrospective review of 12 patients who underwent silicone oil tamponade for repair of retinal detachments. Macular OCT scans and volumetric thickness maps were examined qualitatively and quantitatively.

RESULTS

Volumetric OCT revealed two distinct patterns during silicone oil: macular thickening (Group A) and macular thinning (Group B). In Group A, mean foveal thickness (507 ± 169 µm vs. 407 ± 163 µm, p = 0.003) and mean macular volume (11.6 ± 2.4 mm³ vs. 9.9 ± 1.5 mm³) were significantly increased during tamponade compared to post-oil removal. Group B had significantly decreased mean foveal thickness (210 ± 38 µm vs. 276 ± 58 µm, p = 0.009) and macular volume (7.3 ± 1.8 mm³ vs. 8.4 ± 1.8 mm³) during tamponade. Importantly, resolution of macular changes occurred without further intervention and was associated with improved visual acuity in both groups.

CONCLUSION

Our series suggests that when faced with unexplained macular edema or macular thinning during tamponade, silicone oil removal alone can achieve resolution of these structural changes.

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.

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.

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.

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.