The effect of simultaneous internal tamponade on fluid compartmentalization and its relationship to cell proliferation

Vitreous Substitutes from Bench to the Operating Room in a Translational Approach: Review and Future Endeavors in Vitreoretinal Surgery

Vitreous substitutes are indispensable tools in vitreoretinal surgery. The two crucial functions of these substitutes are their ability to displace intravitreal fluid from the retinal surface and to allow the retina to adhere to the retinal pigment epithelium. Today, vitreoretinal surgeons can choose among a plethora of vitreous tamponades, and the tamponade of choice might be difficult to determine in the ever-expanding range of possibilities for a favorable outcome. The currently available vitreous substitutes have disadvantages that need to be addressed to improve the surgical outcome achievable today. Herein, the fundamental physical and chemical proprieties of all vitreous substitutes are reported, and their use and clinical applications are described alongside some surgical techniques of intra-operative manipulation. The major upcoming developments in vitreous substitutes are extensively discussed, keeping a translational perspective throughout. Conclusions on future perspectives are derived through an in-depth analysis of what is lacking today in terms of desired outcomes and biomaterials technology.

Retinal Detachment in Eyes with Boston Type 1 Keratoprosthesis: Surgical Techniques and Mid-Term Outcomes

PURPOSE

To evaluate the mid-term outcomes of pars plana vitrectomy (PPV) performed for retinal detachment (RD) repair after Boston type 1 keratoprosthesis (KPro) implantation.

METHODS

Retrospective chart review of KPro implanted at the Stein Eye Institute presenting with RD and treated by PPV. Functional success was defined as a postoperative visual acuity (VA) maintained within 2 Snellen lines of the CDVA measured before the development of the RD (baseline) and anatomical success as an attached retina after the PPV. Kaplan-Meyer survival analyses were performed.

RESULTS

Among the 224 KPro performed, 28 (15.2%) RD were identified, of which 21 (9.4%) were included. The mean follow-up was 42.5 ± 27.3 months. Vitreoretinal proliferation was present in 18/21 (85.7%) eyes. Surgical techniques were adapted to the complex anterior segment anatomy of KPro eyes. Anatomical success was achieved in 18/21 (85.7%) eyes. Functional success occurred in 17/21 (81.0%) eyes, and 5/21 (23.8%) eyes reached 20/400 or better VA at final follow-up. The KPro was retained in 11/21 (52.4%) eyes. The retention rate decreased from 94.7% at 1 year to 53.5% at 5 years. The most frequent complications were retroprosthetic membrane (47.6%) and corneal melt (23.8%).

CONCLUSION

Modified PPV techniques resulted in relatively good mid-term anatomic, functional, and retention rate outcomes, given the severity of RD at presentation, and the numerous preoperative comorbidities of KPro eyes.

RECURRENCES OF RETINAL DETACHMENT AFTER RETINECTOMY: Causes and Outcomes

PURPOSE

To evaluate the different mechanisms of retinal detachment recurrence after retinectomy for rhegmatogenous retinal detachment (RD) complicated by proliferative vitreoretinopathy (PVR) and to study its outcome and prognosis.

METHODS

Retrospective, multicenter study conducted between January 2009 and November 2016. Retrospective review of 56 patients with recurrent RD (RRD) after a first relaxing retinectomy.

RESULTS

The secondary retinal attachment rate was 58.9% (33/56 cases). The various mechanisms of RRD were mainly related to PVR (52/56 cases: 93%). This PVR was anterior in 10 cases (21%), posterior in 31 cases (60%), and combined anterior and posterior in 11 cases (21%). The RRD mechanism was not PVR in 4 of the 56 cases. Some of the RRD mechanisms were specific to retinectomy: fibrosis of the edge of the retinectomy (26 cases: 46.4%), beyond-the-edge proliferation (8 cases: 14.3%), and severe inferior retinal folding (2 cases: 3.6%). In the 2 cases of severe inferior retinal folding, the retina could not be reattached. The anatomical outcome and the mechanism of RRD (anterior PVR, posterior PVR, or combined anterior and posterior PVR) were not correlated (P = 0.12). Visual acuity was significantly better only in patients with complete secondary success, that is, having an attached retina after silicone oil removal: mean preoperative visual acuity was 2.01 logarithm of the minimum angle of resolution versus 1.01 logarithm of the minimum angle of resolution postoperatively (P = 0.019).

CONCLUSION

Proliferative vitreoretinopathy caused most of the recurrences, and the anatomical outcome did not depend on the type of PVR involved. Only complete secondary success (attached retina after silicone oil removal) was accompanied by visual acuity improvement.

Two-staged surgery as an alternative to buckle-vitrectomy for rhegmatogenous retinal detachment complicated by choroidal detachment

AIM

To evaluate the outcome and safety profile of short-term perfluorocarbon liquids (PFCL) tamponade in comparison with buckle-vitrectomy in case of rhegmatogenous retinal detachment (RRD) associated with choroidal detachment (CD).

METHODS

Records of patients who underwent surgery for RRD/CD from January 2016 to July 2019 were reviewed retrospectively. The patients were allocated into two groups-group 1 patients underwent buckle-vitrectomy, while those in group 2 underwent a two-staged vitrectomy with short-term (5 days) PFCL tamponade.

RESULTS

The study included 33 eyes (33 patients) with mean age of 50.3 ± 17.2 years. Group 1 included 15 patients, while group 2 included 18. The pre-operative characteristics were similar in both the groups. The mean pre-operative intraocular pressure in group 1 and 2 was 9.1 ± 4.0 and 8.6 ± 5.2 mmHg, respectively (p = 0.755). Retinal re-attachment after single surgery was achieved in 10 (66.7%) and 14 eyes (77.8%), respectively. All the eyes achieved retinal re-attachment after repeat surgery in both the groups (1.40 vs 1.39 surgeries, p = 0.963). Post-surgery visual improvement was seen in 13 (86.7%) and 17 eyes (94.4%), respectively (p = 0.579). Final visual acuity of ≥ 6/60 was obtained in 7 (46.7%) and 9 eyes (50.0%), respectively (p > 0.999). None of the patients needed retinectomy during repeat surgery. None of the patients experienced exaggerated inflammation or intractable raised IOP spike which could not be controlled with medications.

CONCLUSION

Surgical outcomes were similar in both the groups. No clinically apparent toxicity was seen with post-operative short-term PFCL tamponade. Two-staged surgery is a good alternative to buckle-vitrectomy for eyes with RRD associated with CD.

Sandwich technique using a combination of perfluoropropane and silicone oil for inferior retinal detachment

We report a novel surgical sandwich technique using a combination of intraocular perfluoropropane (C₃F₈) and silicone oil for inferior retinal detachment (RD). After conventional pars plana vitrectomy and posterior vitreous detachment induction, fluid-gas exchange using 14% C₃F₈was done. This was followed by silicone oil injection using automated infusion pump to 50% fill of the vitreous cavity under direct visualization to achieve formation of two bubbles - gas bubble superiorly and silicone oil inferiorly. The patient was subsequently asked to maintain upright position. The two immiscible bubbles of C₃F₈and silicone oil provide tamponade to superior and inferior retina, respectively. With time, gas bubble reduces in size with a gradual superior shift of silicone oil. This novel sandwich technique achieves complete attachment of retina and reduces the risk of retinal redetachment in inferior RDs by adequately tamponading the inferior retina.

A New, Heavier-Than-Water Silicone Oil: A Solution of Perfluorohexyloctane in Polydimethylsiloxane

Purpose

To prepare and explore new solutions of semifluorinated alkane in silicone oil, which have a specific gravity slightly higher than silicone oil and vitreous fluid (referred to in the following as heavier-than-water silicone oils (HWSs), and to investigate, in vitro, whether HWSs can be used to plug retina holes, while allowing dehydration of the subretinal space.

Methods

HWS solutions were prepared with silicone oil 5000 and perfluorohexyloctane (F6H8). The stability was investigated under different conditions. The viscosity was determined by means of a capillary viscometer. The surface and interface tension were measured using the ring method.

Results

HWSS are insoluble in an aqueous medium. Densiron®68 (HWS 1.06) is a transparent homogeneous liquid which is slightly heavier (1.06 g/cm3) than water and has a refractive index close to that of vitreous liquid. Densiron®68 (HWS 1.06) has a low viscosity (1480 mPas) and interface tension (40.82 mN/m), making it an effective tamponade in the surgical treatment of an inferior detached retina. In addition, the interfaces between Densiron®68 and other perfluorocarbon liquids are clearly visible. However, the interface layer between Densiron®68 and water is not clear. Finally, all HWSs are stable over the long term at ambient temperatures, as well as physically and thermally resistant.

Conclusions

Due to its physiochemical properties, Densiron®68 could meet the requirements for a heavier-than-water tamponade.

Ocular tolerance and efficacy of short-term tamponade with double filling of polydimethyloxane and perfluoro-n-octane

Objective:

The aim of the study was to evaluate the ocular tolerance and efficacy of double filling with perfluoro-n-octane (n-C8F18) (PFO) and polydimethyloxane (PDMS) as a temporary vitreous substitute in patients with retinal detachment complicated by proliferative vitreoretinopathy (PVR).

Material and methods:

Tamponade was performed in 30 eyes of 30 patients by double filling with 30% PFO and 70% PDMS for an average of 23 (standard deviation 2.2) days. The follow-up visits were scheduled 1 week, 1 month, and 3 months after surgery. The main outcome measures were visual acuity, intraocular pressure (IOP), PVR reproliferation, and electrophysiological parameters.

Results:

The primary success rate was 80% (24/30). Fourteen patients (46.7%) had a postoperative improvement in visual acuity, 12 patients (40.0%) maintained their preoperative visual acuity, and four patients (13.3%) experienced a reduction in visual acuity. The mean postoperative IOP was 19.7 mm Hg (11–32 mm Hg); nine cases (30.0%) developed an IOP increase that was treated with topical drops and/or systemic carbonic anhydrase inhibitors. The electroretinogram (ERG) and the bright flash electroretinogram (bf ERG) parameters showed a statistically significant difference of means between 4- and 8-week follow-up visits.

Conclusion:

Our experience with double filling in selected cases of retinal detachment has been positive. No electroretinographic signs of retinal toxicity and a low incidence of PVR reproliferation were observed.

A new heavy internal tamponade in vitreoretinal surgery: an in vitro study

AimTo study the solubility of perfluorohexyloctane (F6H8) in silicone oil (polydimethylsiloxane (PDMS) 1000) and to measure the viscosity and the specific gravity of the mixture obtained (heavy silicone oil or HSO tamponade) to define the ideal ratio of these components.MethodsThe solubility diagram of the mixture was obtained with the turbidimetric method, indicating the miscibility of F6H8 and silicone oil 1000 at all the useful temperatures. The viscosity was measured in steady shear conditions by using a controlled stress rheometer (Haake RS150) and a double cone/plate (DC 60/4) system, both at 25 and 37 degrees C for different volume per cent compositions of the mixture. The specific gravity was measured at 37 degrees C using a digital densimeter.ResultsA mixture of F6H8 30 v% and PDMS 70 v% was found to be transparent and stable at all the useful temperatures. By combining these proportions of the two substances, a resultant density of 1.06 g/cm(3) was obtained. The viscosity of the 30% F6H8 mixture was 203 mPa.s at 25 degrees C and 163 mPa.s at 37 degrees C respectively.ConclusionsThe ideal F6H8 and silicone oil mixture can be obtained combining 30% of F6H8 with 70% of silicone oil 1000. This mixture seems to have rheological properties useful for its use as an alternative intraocular heavy tamponade.Eye (2008) 22, 1082-1088; doi:10.1038/eye.2008.144; published online 6 June 2008.

Heavy tamponade 1: a review of indications, use, and complications

BACKGROUND

Heavier than water intraocular tamponades have several theoretical advantages over conventional tamponades, especially in the treatment of complicated retinal detachments and proliferative viteroretinopathy of the lower fundus periphery. However, initial clinical series of various heavy tamponades have reported significant complication rates. Therefore, heavy tamponades have not found widespread acceptance. Three recently developed heavy silicone oil tamponades, Oxane HD, Densiron 68, and HWS 46-3000, are much better tolerated and presently seem to enter routine clinical practice.

MATERIALS AND METHODS

Literature review of 21 publications on the clinical application of 9 different heavy tamponades (fluorosilicone, C10F18, F6H8, OL62HV, Oxane HD, O62, F6H8-silicone oil mixture, Densiron 68, and HWS 46-3000).

RESULTS

The first generation (fluorinated silicone and perfluorocarbon liquids) and second generation (partially fluorinated alkanes) of heavy tamponades were associated with relatively high complication rates, for example, tamponade emulsification, intraocular inflammation, and rise in intraocular pressure. The complication spectrum of the new generation of heavy silicone oils (Oxane HD, Densiron 68, and HWS 46-3000) seems to be comparable to conventional silicone oil tamponades while providing better support for the inferior retina and the posterior pole.

CONCLUSION

The recently developed heavy silicone oil tamponades are safe and effective tools for the use of complicated retinal detachments of the inferior fundus.

A NEW HEAVY SILICONE OIL (HWS 46-3000) USED AS A PROLONGED INTERNAL TAMPONADE AGENT IN COMPLICATED VITREORETINAL SURGERY

PURPOSE

To report the results of a prospective pilot study using a new heavy agent, HWS 46-3000, as long-term endotamponade in complicated retinal detachment.

METHODS

Thirty-two consecutive patients were enrolled in the study. Indications for enrollment included retinal detachment with proliferative vitreoretinopathy arising from inferior or posterior tears. The patients underwent pars plana vitrectomy, membrane peeling, and HWS 46-3000 filling. Follow-up examinations were scheduled at 1 day to 7 days and 1 month to 3 months after initial surgery and 7 days and 1 month to 6 months after endotamponade removal.

RESULTS

At baseline examination, mean best-corrected Snellen visual acuity was 2.44 logarithm of the minimal angle of resolution (logMAR). HWS 46-3000 was removed after 45 days to 96 days. Initial retinal reattachment was achieved in all eyes. HWS 46-3000 endotamponade was associated with a success rate of 84.6% with a single surgery and an overall success rate of 100% at 6 months with the second operation and conventional silicone oil endotamponade. At 6 months, mean best-corrected visual acuity was +1.09 logMAR (P < 0.0001). Complications were posterior subcapsular cataract formation (100%), membrane formation (3 eyes, 9%), and increased intraocular pressure (1 eye). Emulsification and intraocular inflammation were not observed.

CONCLUSION

HWS 46-3000 was well tolerated, effective in the inferior quadrants with a low incidence of membrane development. The main complication was the high rate of tamponade-related cataract formation.

The combined use of perfluorohexyloctane (F6H8) and silicone oil as an intraocular tamponade in the treatment of severe retinal detachment

BACKGROUND

The purpose of this study was to investigate the combined use of perfluorohexyloctane (F6H8) and 1,000-centistoke silicone oil as a long-term intraocular tamponade in the treatment of complicated retinal detachment.

METHODS

Sixty consecutive eyes affected by complicated retinal detachment with (1) retinal breaks of the lower two quadrants and severe proliferative vitreoretinopathy, (2) inferior giant retinal tear, (3) penetrating trauma or (4) choroidal detachment underwent pars plana vitrectomy using a combined internal tamponade of F6H8 and silicone oil. The double filling (DF) was removed after 40-50 days. The anatomical outcome and the complications due to the DF are reported.

RESULTS

Retinal reattachment was achieved in all but one patient. Thirty-eight (63%) eyes needed further surgery with silicone oil tamponade. Silicone oil was successfully removed in 22 eyes. Sixteen (27%) eyes had retained silicone oil at the last follow-up examination. One eye showed persistent retinal detachment despite further surgery. Main complications of the DF were recurrent retinal detachment of the upper retina in six (10%) eyes and membrane formation in 25 (42%) eyes.

CONCLUSIONS

A combined internal tamponade of F6H8 and silicone oil may be a useful tool in the treatment of complicated retinal detachment involving the lower quadrants of the retina.

Anatomical and Functional Outcomes after Heavy Silicone Oil Tamponade in Vitreoretinal Surgery for Complicated Retinal Detachment

PURPOSE

To evaluate the effectiveness and safety of a heavy silicone oil (HSO) tamponade for complicated retinal detachment (RD) surgery.

DESIGN

Prospective consecutive interventional case series study.

PARTICIPANTS

The study included 26 patients with RD complicated by severe proliferative vitreoretinopathy (PVR) in the inferior quadrants.

METHODS

All patients underwent pars plana vitrectomy with an internal tamponade using HSO. This tamponade was obtained by mixing 30% by volume perfluorohexyloctane and 70% by volume silicone oil, 1000 millipascal-seconds (polydimethylsiloxane 1000).

MAIN OUTCOMES MEASURES

Anatomical and functional results and complications at 1 year of follow-up.

RESULTS

Twenty-four of 26 patients achieved anatomical success, defined as complete retinal reattachment. Postoperative visual acuity (VA) values ranged from hand movements to 20/25, with 69.2% of patients obtaining VA better than 20/400. Postoperative complications included early postoperative ocular hypertension in 30.7% of cases, which was easily controlled. Dispersion was noted in 1 case and was not felt to be significant. A cataract requiring surgical removal developed in 2 cases, and an after cataract developed in 3 cases.

CONCLUSIONS

In this pilot study, the HSO tamponade obtained by mixing 30% perfluorohexyloctane and 70% polydimethylsiloxane 1000 was associated with a high rate of anatomical success after vitrectomy in cases of RD complicated by severe PVR (greater than CP-6 and greater than CA-6 [updated Retina Society PVR classification]).

A pilot study on the use of a perfluorohexyloctane/silicone oil solution as a heavier than water internal tamponade agent

AIMS

To report a prospective two centred non-comparative interventional pilot study of a solution of perfluorohexyloctane and silicone oil (Densiron-68) as a heavier than water internal tamponade.

METHODS

42 consecutive patients were recruited. The indications include proliferative vitreoretinopathy, retinal detachments arising from inferior retinal breaks, and inability to posture.

RESULTS

The success rate with one operation using Densiron was 81% and with further surgery 93%. At the end of the study all tamponade agents were removed in 90% of patients. Visual acuity improved from mean logMAR of 1.41 (SD 0.64) to 0.94 (SD 0.57), p = 0.001. There was little evidence of dispersion and excessive inflammation.

CONCLUSION

This new tamponade agent is being compared to conventional silicone oil in a prospective international randomised trial.

A pilot study on the use of silicone oil–RMN3 as heavier-than-water endotamponade agent

AIMS

This work was conducted to report an interventional non-comparative pilot study using Oxane HD, a mixture of ultra-purified silicone oil and RMN3, a partially fluorinated olefin, as heavier-than-water internal tamponade.

METHODS

Twenty-eight consecutive patients were recruited for this study. Indications included recurrent retinal detachment (RD) with proliferative vitreoretinopathy (PVR) (stage > or =C2) arising from inferior or posterior tears, recurrences after vitreoretinal surgery, penetrating trauma and combined rhegmatogenous and choroidal detachment. The patients underwent a pars plana vitrectomy, membrane peeling, and Oxane HD was used as long-term internal tamponade.

RESULTS

Oxane was removed after 88 days (range 45-96 days) and exchanged with BSS in five eyes, long-acting gas in 14 eyes and with silicone oil in nine eyes. Retinal reattachment was achieved in 15 eyes. The overall anatomical success rate obtained using Oxane HD was 53.5%. In 15 patients with previous marked scleral buckling, the success rate was 26%: in nine patients recurrent RD occurred in the inferior sector, in five patients new tears were detected in the lower sectors; membrane formation was observed in 15 eyes. In 13 patients without marked scleral indent, the success rate was 84.6%. There was no evidence of dispersion and excessive inflammation.

CONCLUSION

Oxane HD may be a useful tool in complicated RD with large inferior breaks, inferior PVR or combined rhegmatogenous, and choroidal detachment without marked scleral buckling, which put the eye profile out of shape, led to a higher failure rate and reduced the tamponading effectiveness of Oxane HD.

Long-Term Vitreous Replacement with Perfluorohexyloctane and Silicone Oil: Preliminary Reports of a Multicentric Study

AIM

To report on the use of a combined intra-ocular tamponade with silicone oil and perfluorohexyloctane (F(6)H(8)) in the treatment of complex retinal detachment.

DESIGN

A prospective consecutive interventional case series from seven study centres.

PARTICIPANTS

69 patients presenting a retinal detachment with proliferative vitreoretinopathy (PVR) and retinal breaks of the inferior two quadrants of the fundus.

METHOD

Patients were divided into two groups: (1) 28 eyes which had not been operated on before; (2) 41 eyes affected by recurrent retinal detachment that had had unsuccessful previous surgery with silicone oil or gas tamponade. A pars plana vitrectomy, membrane peeling and -- when necessary -- a retinotomy were performed; the vitreous cavity was filled with two thirds of F(6)H(8) and one third of silicone oil 1,000 mPas (double filling, DF). The endotamponade was removed after 30-45 days (median 38) and replaced by balanced salt solution or silicone oil according to the condition of the retina.

RESULTS

Retinal reattachment was achieved in 52 out of 69 cases (75%) 6 months after removal of the DF without any endotamponade.

CONCLUSION

The DF with F(6)H(8) and silicone oil allows a good endotamponading to the inferior retina and the posterior pole. The DF appeared to be well tolerated. Further studies are necessary to evaluate whether a DF is advantageous in respect to silicone oil filling alone in case of retinal breaks and PVR of the inferior retina.

Use of perfluorohexyloctane as a long-term internal tamponade agent in complicated retinal detachment surgery

PURPOSE

To report the use of perfluorohexyloctane, a liquid semifluorinated alkane that is heavier than water, as an internal tamponade agent in surgery for complicated retinal detachments.

DESIGN

A consecutive interventional case series from three study centers.

METHODS

In 23 consecutive eyes (23 patients, 19 men and four women, mean +/- standard deviation (SD) age of 58.5 years +/- 16.1) perfluorohexyloctane was used for long-term internal tamponade. Included were eyes with complicated retinal detachment involving the lower two quadrants of the fundus. Excluded were patients with diseases in the fellow eye or severe systemic disease. A pars plana vitrectomy was performed, including membrane peeling and retinotomy where necessary.

RESULTS

The mean duration for perfluorohexyloctane being left in situ was 76 days (SD 37.64) (range, 35-202 days). Four weeks following the removal of perfluorohexyloctane 19 of the 23 patients had total reattachment of the retina; three eyes had a recurrence of retinal detachment. One patient was lost to follow-up. The mean follow-up after perfluorohexyloctane removal was 97 days (range, 48 to 169 days). Cataract formation or progression was noted in nine of the 10 eyes. There were two cases with high intraocular pressures. Dispersion into small droplets was observed as early as 3 days postoperatively in three of the 23 patients. At least 12 of the 23 patients had an obvious dispersion by the time of perfluorohexyloctane removal. There was no sign of optic atrophy, retinal necrosis, or retinal vascular occlusion.

CONCLUSION

Perfluorohexyloctane was tolerated as a long-term internal tamponade agent without obvious signs of damage to the retina or optic disk. Of all the complications noted, the most common was that of dispersion of the perfluorohexyloctane bubble into droplets.

Management of inferior retinal breaks during pars plana vitrectomy for retinal detachment

AIMS

To determine whether it is necessary to support inferior retinal breaks with a scleral explant during pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RD).

METHODS

A prospective study was carried out on nine eyes of nine consecutive patients undergoing PPV for primary RD with associated inferior retinal breaks and no significant proliferative vitreoretinopathy.

RESULTS

Eight eyes were successfully reattached with a single operation. No cases presented with redetachment because of failed closure of the original inferior breaks.

CONCLUSIONS

It is not necessary to support inferior retinal breaks with a scleral explant during PPV for primary RD repair in selected cases.

Perfluorocarbons and semifluorinated alkanes

The introduction of perfluorocarbons (PFCs) and, more recently, semifluorinated alkanes (SFAs) has greatly facilitated vitreoretinal surgery. A distinction is made between the use of these substances as intraoperative tools and internal tamponade agents. This article reviews the physical and chemical properties of PFCs and SFAs and discusses the indications, results, and complications. The effectiveness of these substances as internal tamponade agents is discussed with reference to the specific gravity, contact angle, viscosity and ability to fill model eye chambers and the vitreous cavity. The evidence for the toxicity in animal and human is examined.

Histopathology of rabbit eyes with silicone-fluorosilicone copolymer oil as six months internal retinal tamponade

Silicone-fluorosilicone copolymer oil has low viscosity (175-185 cSt) and is heavier than water (density, 1.16 g cm-3). Short term retinal tolerance (within 2 months) of the silicone-fluorosilicone copolymer oil has been reported to be the same as that of currently used intraocular silicone oil. Ocular response of the purified silicone-fluorosilicone copolymer oil were examined clinically and histopathologically from 2.5 months to 6 months after vitreous cavity injection in rabbit phakic eyes, and compared the oil tolerance with that of purified silicone oil (0.97 g cm-3, 5000 cSt). The effects in anterior chamber also were examined within 4 weeks of the silicone-fluorosilicone copolymer oil injection in different rabbits. Silicone-fluorosilicone copolymer oil recovered from the vitreous cavity at 6 months was analysed for cholesterol and retinol content by high performance liquid chromatography. Because of its low viscosity, silicone-fluorosilicone copolymer oil was easy to inject and remove from the vitreous cavity with a 20-G needle. After the vitreous injection, discrete droplet formation by the silicone-fluorosilicone copolymer oil occurred more easily than by silicone oil. Medullary ray detachment was seen in a silicone oil-, and some silicone-fluorosilicone copolymer oil-injected eyes at 4-6 months. Histopathologically, after 3-6 months disappearance of outer plexiform layer and disorganization of the photoreceptor layer of silicone oil-, and silicone-fluorosilicone copolymer oil-injected eyes were seen in the superior and the inferior retina, respectively. Migration of the photoreceptor cell nuclei to the photoreceptor layer was found in the inferior retina of silicone-fluorosilicone copolymer oil-injected eyes at 5-6 months. Small droplets ingested by mononuclear cells were found in the vitreous cavity or preretina at 4-6 months in silicone-fluorosilicone copolymer oil-injected eyes. After the anterior chamber injection, silicone-fluorosilicone copolymer oil induced endothelial cell damage in the area where the oil contacted continuously. Retinol and cholesterol were identified in silicone-fluorosilicone copolymer oil removed from the vitreous cavity. Silicone-fluorosilicone copolymer oil may be useful as an intraoperative device in retinal detachment surgery and as a short term (up to about 2 months) retinal tamponade but we do not recommend it for long term retinal tamponade.