Perfluorodecalin-induced intravitreal inflammation

Microvascular changes after pars plana vitrectomy for rhegmatogenous retinal detachment repair: A comparative study based on gas tamponade agent

PURPOSE

The purpose of this study was to investigate the effect of gas tamponade on microvascular changes in patients with rhegmatogenous retinal detachment (RRD), who underwent pars plana vitrectomy (PPV), using optical coherence tomography angiography (OCTA).

METHODS

Participants in this study were 48 patients with RRD, who were treated with PPV and gas tamponade without internal limiting membrane peeling. All participants underwent slit-lamp examination, fundoscopy, spectral domain-optical coherence tomography and optical coherence tomography angiography at month 6 postoperatively. The fellow untreated eyes were also examined and served as the control data.

RESULTS

A statistically significant enlargement in the foveal avascular zone (FAZ) in both the superficial (p = 0.002) and the deep capillary plexus (p = 0.01) was noticed 6 months postoperatively in patients with RRD treated with PPV compared to the fellow eyes. The foveal avascular zone perimeter was increased in the operated eyes in the deep capillary plexus (p = 0.0003) and the foveal avascular zone circularity was decreased in both the superficial (p = 0.045) and the deep capillary plexus (p < 0.001) compared to the fellow eyes. The vessel density was not significantly different between the operated and the fellow eyes in the superficial and the deep capillary plexus. The vessel density and the foveal avascular zone parameters were comparable between the C3F8 and SF6 groups.

CONCLUSION

Specific microvascular indices as measured by OCTA were statistically different between the operated and the fellow eyes in the superficial and deep capillary plexus. C3F8 and SF6 as gas tamponades did not seem to differ in their impact on the microvascular parameters.

Short-term perfluorocarbon liquid tamponade in choroidal melanoma endoresection

Purpose

To report the use of short-term perfluorocarbon liquid (ST-PFCL) tamponade following choroidal melanoma endoresection.

Methods

Patients with medium to large choroidal melanomas not amenable to primary Ruthenium-106 brachytherapy underwent choroidal melanoma endoresection following gamma knife radiosurgery. During surgery, a complete vitrectomy was performed followed by PFCL injection, then a retinectomy with endoresection of the melanoma and underlying choroid was done. Complete PFCL filling was then achieved, and laser barrage surrounding the retinectomy was done. A Ruthenium-106 plaque was then inserted. Postoperatively, supine positioning was maintained for three days followed by plaque and PFCL removal with silicone oil injection. Several months later, silicone oil was removed.

Results

Four eyes of 4 patients underwent endoresection with ST-PFCL tamponade. Mean height of tumor was 8.6 ± 0.85 mm, while mean maximal basal diameter was 11.5 ± 1.1 mm. Mean preoperative logMAR best corrected visual acuity (BCVA) was 1.76 ± 0.18. All patients underwent preoperative gamma knife radiosurgery and postoperative brachytherapy. There were no major intraoperative or postoperative complications. All patients underwent silicone oil injection with PFCL/plaque removal after 3 days, while silicone oil was removed after 4 ± 1.2 months. Mean postoperative logMAR BCVA 3 months following oil removal was 0.89 ± 0.22 (p = 0.02). Mean follow-up duration was 17 ± 2.8 months. No patient developed local tumor recurrence, distant metastases, or vitreoretinal complications by final visit.

Conclusion

ST-PFCL tamponade may reduce the risk of intraoperative and postoperative complications associated with choroidal melanoma endoresection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40942-022-00395-z.

Vitreous inflammation and macular edema secondary to perfluoro-n-octane toxicity

Although it is not frequent, residual perfluoro-n-octane elicits an inflammatory response in form of macroscopic white flake-like material on intraocular structures formed by macrophages with intracellular vacuoles containing it. Macular edema could be another manifestation of this entity which, to our knowledge, has not been described so far. We describe an unusual case of intravitreal inflammation and macular edema secondary to the presence of residual perfluoro-n-octane after a surgical intervention of retinal detachment.

Double Retinal Tamponade for Treatment of Rhegmatogenous Retinal Detachment with Proliferative Vitreoretinopathy and Inferior Breaks

Purpose

To evaluate the efficacy and safety of the simultaneous use of short-term perfluoro-n-octane (PFO) with perfluoropropane (C3F8) gas to achieve retinal reattachment in eyes with rhegmatogenous retinal detachment (RRD) with proliferative vitreoretinopathy (PVR) grade C and multiple retinal breaks including inferior breaks.

Design

This is a prospective interventional case series study. Patients and Methods. The study was a prospective noncomparative interventional study. It included 30 eyes of 30 patients who had RRD with PVR grade C and multiple retinal breaks including inferior tears attending the vitreoretinal unit of Minia University Hospital, Egypt. The mean age was 50.2 ± 10.63 years; 18 patients were females and 12 were males. Combined phacoemulsification and 23 G pars plana vitrectomy (PPV) with double retinal tamponade by C3F8 and PFO were done, and PFO was removed in 10–14 days. The patients were followed up for one year. The primary outcome was to achieve successful retinal reattachment, and the secondary outcomes were visual improvement and occurrence of complications.

Results

Successful retinal reattachment was obtained in 28 eyes out of 30 (93.3%), and 2 eyes (6.7%) had recurrent RD. Best-corrected distance visual acuity (BCDVA) in logMAR was significantly improved from baseline 1.74 ± 0.05 to 0.93 ± 0.04, 0.82 ± 0.05, 0.80 ± 0.07, and 0.73 ± 0.055 at follow-up visits 3, 6, and 9 months and one year, respectively (P ≤ 0.001). There were no serious ocular complications recorded.

Conclusions

The results of this study indicated that primary vitrectomy with simultaneous use of both C3F8 and short-term PFO as retinal tamponades was effective and safe in the management of complex cases of RRD with PVR grade C and inferior breaks. This trial is registered with NCT04168255.

Retinal Tamponades: Current Uses and Future Technologies

Purpose of Review

In this article, the current use and limitations of existing retinal tamponades are discussed. Potential novel developments that address those limitations are subsequently highlighted, along with areas of future improvements.

Recent Findings

While retinal tamponades have existed for decades and improved the treatment of retinal detachments, many problems still exist with their use, including inadequate tamponade of the inferior retina, toxicity from retained heavy liquids, glaucoma, and keratopathy, among others. New advancements in the components of heavy liquids and vitreous substitutes aim to mitigate those issues.

Summary

Existing retinal tamponades, including perflurocarbon heavy liquids, fluorinated gases, and silicone oil, have specific limitations that cause potentially avoidable morbidity. New developments, such as heavy silicone oil, novel vitreous gels, and future avenues of approach, such as potentially reabsorbing heavy liquids may help increase our ability to treat retinal detachments with fewer complications.

Tamponade in surgery for retinal detachment associated with proliferative vitreoretinopathy

BACKGROUND

Retinal detachment (RD) with proliferative vitreoretinopathy (PVR) often requires surgery to restore normal anatomy and to stabilize or improve vision. PVR usually occurs in association with recurrent RD (that is, after initial retinal re-attachment surgery), but occasionally may be associated with primary RD. Either way, for both circumstances a tamponade agent (gas or silicone oil) is needed during surgery to reduce the rate of postoperative recurrent RD.

OBJECTIVES

The objective of this review was to assess the relative safety and effectiveness of various tamponade agents used with surgery for RD complicated by PVR.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (the Cochrane Library 2019, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to January 2019), Embase (January 1980 to January 2019), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2019), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 2 January 2019.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) on participants undergoing surgery for RD associated with PVR that compared various tamponade agents.

DATA COLLECTION AND ANALYSIS

Two review authors screened the search results independently. We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified four RCTs (601 participants) that provided data for the primary and secondary outcomes. Three RCTs provided data on visual acuity, two reported on macular attachment, one on retinal reattachment and another two on adverse events such as RD, worsening visual acuity and intraocular pressure. Study Characteristics Participants' characteristics varied across studies and across intervention groups, with an age range between 21 to 89 years, and were predominantly men. The Silicone Study was conducted in the USA and consisted of two RCTs: (silicone oil versus sulfur hexafluoride (SF₆) gas tamponades; 151 participants) and (silicone oil versus perfluropropane (C₃F₈) gas tamponades; 271 participants). The third RCT compared heavy silicone oil (a mixture of perfluorohexyloctane (F₆H₈) and silicone oil) with standard silicone oil (either 1000 centistokes or 5000 centistokes; 94 participants). The fourth RCT compared 1000 centistokes with 5000 centistokes silicone oil in 85 participants. We assessed most RCTs at low or unclear risk of bias for most 'Risk of bias' domains. Findings Although SF₆ gas was reported to be associated with worse anatomic and visual outcomes than was silicone oil at one year (quantitative data not reported), at two years, silicone oil compared to SF₆ gas showed no evidence of a difference in visual acuity (33% versus 51%; risk ratio (RR) 1.57; 95% confidence interval (CI) 0.93 to 2.66; 1 RCT, 87 participants; low-certainty evidence). At one year, another RCT comparing silicone oil and C₃F₈ gas found no evidence of a difference in visual acuity between the two groups (41% versus 39%; RR 0.97; 95% CI 0.73 to 1.31; 1 RCT, 264 participants; low-certainty evidence). In a third RCT, participants treated with standard silicone oil compared to those receiving heavy silicone oil also showed no evidence of a difference in the change in visual acuity at one year, measured on logMAR scale ( mean difference -0.03 logMAR; 95% CI -0.35 to 0.29; 1 RCT; 93 participants; low-certainty evidence). The fourth RCT with 5000-centistoke and 1000-centistoke comparisons did not report data on visual acuity. For macular attachment, participants treated with silicone oil may probably experience more favorable outcomes than did participants who received SF₆ at both one year (quantitative data not reported) and two years (58% versus 79%; RR 1.37; 95% CI 1.01 to 1.86; 1 RCT; 87 participants; low-certainty evidence). In another RCT, silicone oil compared to C₃F₈ at one year found no evidence of difference in macular attachment (RR 1.00; 95% CI 0.86 to 1.15; 1 RCT, 264 participants; low-certainty evidence). One RCT that compared 5000 centistokes to 1000 centistoke reported that retinal reattachment was successful in 67 participants (78.8%) with first surgery and 79 participants (92.9%) with the second surgery, and no evidence of between-group difference (1 RCT; 85 participants; low-certainty evidence). The fourth RCT that compared standard silicone oil with heavy silicone oil did not report on macular attachment. Adverse events In one RCT (86 participants), those receiving standard 1000 centistoke silicone oil compared with those of the 5000 centistoke silicone oil showed no evidence of a difference in intraocular pressure elevation at 18 months (24% versus 22%; RR 0.90; 95% CI 0.41 to 1.94; low-certainty evidence), visually significant cataract (49% versus 64%; RR 1.30; 95% CI 0.89 to 1.89; low-certainty evidence), and incidence of retina detachment after the removal of silicone oil (RR 0.36 95% CI 0.08 to 1.67; low-certainty evidence). Another RCT that compared standard silicone oil with heavy silicone oil suggests no difference in retinal detachment at one year (25% versus 22%; RR 0.89; 95% CI 0.54 to 1.48; 1 RCT; 186 participants; low-certainty evidence). Retinal detachment was not reported in the RCTs that compared silicone oil versus SF₆ and silicone oil versus to C₃F₈.

AUTHORS' CONCLUSIONS

There do not appear to be any major differences in outcomes between C₃F₈ and silicone oil. Silicone oil may be better than SF₆ for macular attachment and other short-term outcomes. The choice of a tamponade agent should be individualized for each patient. The use of either C₃F₈ or standard silicone oil appears reasonable for most patients with RD associated with PVR. Heavy silicone oil, which is not available for routine clinical use in the USA, may not demonstrate evidence of superiority over standard silicone oil.

Perfluorocarbon Liquid Vs. Subretinal Fluid Drainage during Vitrectomy for the Primary Repair of Rhegmatogenous Retinal Detachment: A Comparative Study

PURPOSE

To compare the anatomical and functional results achieved with subretinal fluid drainage (SRFD) and perfluorocarbon liquid (PFCL) use in patients with rhegmatogenous retinal detachment (RRD) treated by primary pars plana vitrectomy (PPV).

METHODS

The study included 162 eyes of 162 patients who underwent PPV for RRD, either with PFCL (n = 108) or SRFD (n = 54). The two groups were matched in 2:1 ratio for age, gender, and lens status. Groups were compared for rates of retinal reattachment, visual improvement, and the occurrence of recurrent RRD and any other postoperative complications.

RESULTS

Both groups had a single surgery success rate of 90.7%, and 100% of retinas were reattached by the end of follow-up. Both groups had similar final VA (0.30 ± 0.39 logMAR in the SRFD group and 0.35 ± 0.44 in the PFCL group; p = 0.48) and degrees of visual improvement (0.64 ± 0.75 logMAR in the SRFD group and 0.59 ± 0.89 in the PFC group; p = 0.71). Complication rates were also similar between groups. The rate of additional interventions was higher (although not statistically significant) in the PFCL group than the SRFD group, due to cases of PFCL retention (4.6% vs. 1.8%, respectively).

CONCLUSIONS

Both PFCL and SRFD achieved excellent results in terms of retinal reattachment and visual improvement, and have comparable safety profiles. A slightly higher rate of additional surgeries was found in the PFCL group. These findings indicate that PFCL are not necessary in routine PPV for RRD, as they do not improve the results achieved with SRFD and may be less cost-effective due to their higher price and potential for a higher rate of additional surgeries.

Management of giant retinal tears with vitrectomy and perfluorocarbon liquid postoperatively as a short-term tamponade

PurposeThe purpose of this study was to study outcomes after using perfluorocarbon liquid (PFCL) as a short-term postoperative vitreous substitute in eyes with retinal detachment from giant retinal tears (GRTs).Patients and methodsA retrospective consecutive case series of patients with retinal detachment from GRT, who underwent vitrectomy using PFCL as short-term postoperative retinal tamponade. PFCL was left in the eye for a mean of 6.7 days (range 7-8 days) and then replaced with gas or silicone oil (SO). The anatomical and functional outcomes and postoperative complications are reported.ResultsA total of 30 eyes of 29 patients with a follow-up of 26.8 months (range 9-55 months) were included. GRTs had a mean size of 150° (range 90°-270°) with 46.6% of eyes with a tear of >180°. Intraoperative retinal re-attachment was achieved in all cases. No cases of retinal slippage were recorded. Four eyes (13.3%) had re-detachment and further surgery required. At final review, 27 eyes (90.9%) had attached retinas, while the remaining 9.1% had SO in situ. The visual acuity improved in 70% of eyes with 41% improving at least 2 Snellen lines and 35% with visual acuity of 6/12 or better. Mild anterior uveitis developed in six eyes (20%), which resolved on topical steroids. Glaucoma developed in one eye and was controlled medically.ConclusionOur study supports the safety and efficacy of PFCL as a short-term postoperative tamponade in cases of GRTs. As it reduces retinal slippage, the use of SO as a primary tamponade decreased in significant proportion of cases.

Perfluorocarbon liquid: its application in vitreoretinal surgery and related ocular inflammation

The application of perfluorocarbon liquids has been well acclaimed in vitreoretinal surgery. Its unique physical properties make it an ideal intraoperative tool to improve the efficiency and safety of surgical procedures in complicated cases. The main functions of perfluorocarbon liquids in vitreoretinal surgery include relocating and fixing the detached retina, displacing the subretinal and subchoroidal to fluid anteriorly, revealing proliferative vitreous retinopathy (PVR) for further maneuvers, protecting the macula from exposure to chemicals with potential toxicity, and assisting the removal of foreign body. The related clinical applications include retinal detachment with severe proliferative vitreoretinopathy, giant tear, diabetic retinopathy (DR), retinopathy of prematurity (ROP), and posterior dislocated crystalline and intraocular lenses. The application of perfluorocarbon liquids has been expended over the past fewer years. Several PFCLs related ocular inflammations have been observed in in vitro studies, animal studies, and clinical follow-up. The complete removal of PFCLs is recommended at the end of the surgery in most cases.

Inflammation induced by perfluorocarbon liquid: intra- and postoperative use

Perfluorocarbon liquids (PFCLs) are useful and safe surgical tools in vitreoretinal surgery. The use of PFCL as a tamponade has been controversial due to the corneal toxicity, retinal infiltration, and inflammatory reaction in experimental studies. Several authors have studied in humans the anatomical and functional outcome and adverse effects of perfluorocarbon liquids used as short-, medium-, and long-term tamponade. PFCLs develop dispersion a few days after injection and droplets may move into the anterior chamber and cause corneal endothelial damage. When PFCLs are used as postoperative tamponades for more than one week, a foreign-body inflammatory reaction is observed in up to 30% of cases but such a reaction does not induce PVR, and it resolves after removal of PFCLs. Although most clinical studies have found no signs of retinal toxicity such as progressive visual acuity deterioration or macular anatomical changes, few performed ERG or retinal histological analysis.

Tamponade in surgery for retinal detachment associated with proliferative vitreoretinopathy

BACKGROUND

Retinal detachment (RD) with proliferative vitreoretinopathy (PVR) often requires surgery to restore normal anatomy and to stabilize or improve vision. PVR usually occurs in association with recurrent RD (that is, after initial retinal re-attachment surgery) but occasionally may be associated with primary RD. Either way, a tamponade agent (gas or silicone oil) is needed during surgery to reduce the rate of postoperative recurrent RD.

OBJECTIVES

The objective of this review was to assess the relative safety and effectiveness of various tamponade agents used with surgery for retinal detachment (RD) complicated by proliferative vitreoretinopathy (PVR).

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 5), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to June 2013), EMBASE (January 1980 to June 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 26 June 2013.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of participants undergoing surgery for RD associated with PVR that compared various tamponade agents.

DATA COLLECTION AND ANALYSIS

Two review authors screened the search results independently. We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

The review included 516 participants from three RCTs. One study was conducted in the USA and consisted of two trials: the first trial randomized 151 adults to receive either silicone oil or sulfur hexafluoride (SF6) gas tamponades; and the second trial randomized 271 adults to receive either silicone oil or perfluropropane (C3F8) gas tamponades. The third trial was a multi-center international trial and randomized 94 participants (age range not specified) to receive heavy silicone oil (a mixture of perfluorohexyloctane (F6H8) and silicone oil) versus standard silicone oil (either 1000 centistokes or 5000 centistokes, per the surgeon's preference).In participants with RD associated with PVR, outcomes after pars plana vitrectomy and infusion of either silicone oil, perfluropropane gas, or sulfur hexafluoride gas appeared comparable for a broad variety of cases. There were no significant differences between silicone oil and perfluoropropane gas in terms of the proportion of participants achieving at least 5/200 visual acuity (risk ratio (RR) 0.97; 95% confidence interval (CI) 0.73 to 1.31) or achieving macular attachment (RR 1.00; 95% CI 0.86 to 1.15) at a minimum of one year. Although sulfur hexafluoride gas was reported to be associated with significantly worse anatomic and visual outcomes than was silicone oil at one year (quantitative data not reported), there were no significant differences between silicone oil and sulfur hexafluoride gas in terms of achieving at least 5/200 visual acuity at two years (RR 1.57; 95% CI 0.93 to 2.66). For macular attachment, participants treated with silicone oil received significantly more favourable outcomes than did participants who received sulfur hexafluoride at both one year (quantitative data not reported) and two years (RR 1.37; 95% CI 1.01 to 1.86). The first two trials did not perform any sample size calculation or power detection. In the third trial, which had a power of 80% to detect differences, heavy silicone oil was not shown to be superior to standard silicone oil. There were no significant differences between standard silicone oil and heavy silicone oil in the change in visual acuity at one year using adjusted mean logMAR visual acuity (mean difference -0.03 logMAR; 95% CI -0.35 to 0.29). Adverse events were not reported for the first two trials. For the third trial, only the total number of adverse events was reported, and adverse events for each group were not specified. Of the 94 participants, four died, 26 had recurrent retinal detachment, 22 developed glaucoma, four developed a cataract, and two had capsular fibrosis.All three trials employed adequate methods for random sequence generation and allocation concealment. None of the trials employed masking of participants and surgeons, and only the third trial masked outcome assessors. The first trial had a large portion of participants excluded from the final analyses, while the other two trials were at low risk of attrition bias. All trials appear to be free of reporting bias. The first two trials were funded by the National Eye Institute, and the third trial was funded by the German Research Foundation.

AUTHORS' CONCLUSIONS

The use of either perfluropropane or standard silicone oil appears reasonable for most patients with RD associated with PVR. Because there do not appear to be any major differences in outcomes between the two agents, the choice of a tamponade agent should be individualized for each patient. Heavy silicone oil, which is not available for routine clinical use in the USA, has not demonstrated evidence of superiority over standard silicone oil.

Tamponade in surgery for retinal detachment associated with proliferative vitreoretinopathy

BACKGROUND

Retinal detachment (RD) with proliferative vitreoretinopathy (PVR) often requires surgery. During surgery, a tamponade agent is needed to reduce the rate of recurrent retinal detachment.

OBJECTIVES

The objective of this review was to evaluate the benefits and adverse outcomes of surgery with various tamponade agents.

SEARCH STRATEGY

We searched the Cochrane Controlled Register (CENTRAL), MEDLINE, EMBASE, Latin America and Carribbean Health Sciences (LILACS) and the UK Clinical Trials Gateway (UKCTG). There were no language or date restrictions in the search for trials. The electronic databases were last searched on 9 July 2009.

SELECTION CRITERIA

We included randomized clinical trials comparing patients treated with various tamponade agents.

DATA COLLECTION AND ANALYSIS

Two individuals screened the search results independently. One study with two trials was eligible for inclusion in the review.

MAIN RESULTS

One study with two trials was included in the review. The first trial randomized 151 eyes to receive either silicone oil or sulfur hexafluoride (SF(6)) gas tamponades; the second trial randomized 271 eyes to receive either silicone oil or perfluropropane (C(3)F(8)) gas tamponades. In patients with RD associated with PVR, pars plana vitrectomy and infusion of either silicone oil or perfluropropane gas appear comparable for a broad variety of cases. Sulfur hexafluoride gas was associated with worse anatomic and visual outcomes than either silicone oil or perfluropropane gas.

AUTHORS' CONCLUSIONS

The use of either C(3)F(8) or silicone oil appears reasonable for most patients with RD associated with PVR. Because there do not appear to be any major differences in outcomes between the two agents, the choice of a tamponade agent should be individualized for each patient.

Biocompatibility assessment of liquid artificial vitreous replacements: relevance of in vitro studies

The biocompatibility of liquid artificial vitreous replacements is generally assessed by performing tests in animal models before their clinical use, whereas in vitro experimentation is seldom carried out due to their physico-chemical characteristics. Since their introduction in vitreoretinal surgery, however, the use of some certified vitreous replacements has been discouraged after clinical trials, because of the occurrence of serious side effects. This observation suggests that the tests currently performed for biocompatibility assessment cannot fully guarantee their safety when they are used in humans. Here we review the available literature on in vitro biocompatibility testing of liquid artificial vitreous replacements and survey our own experience on the subject, obtained by using primary retinal cell cultures, seeded on micro-porous inserts. We suggest that in vitro biocompatibility assessment, conducted before experiments in animal models, could improve the required safety evaluation and decrease the risk of undesired side effects, as well as providing a beneficial reduction of animal experimentation.

Perfluoro-n-octane as a postoperative vitreoretinal tamponade in the management of giant retinal tears

BACKGROUND

Despite recent advances in giant retinal tear repair, retinal redetachment remains an issue. This may be due to inadequate retinal tamponade with silicone oil or perfluorocarbon gas that allows fluid to seep back under the edge of the tear. We propose short-term postoperative retinal tamponade with perfluoro-n-octane liquid to overcome this problem. Theoretical advantages include the reduced likelihood of proliferative vitreoretinopathy. It is easier to remove than silicone oil due to its lower viscosity, and supine posturing is more manageable from a patient perspective.

METHODS

A retrospective case series of 16 giant retinal tear repairs without significant proliferative vitreoretinopathy is presented. Lens-sparing vitrectomy was performed with endolaser to the edge of the tear and the entire retinal periphery. Scleral buckling was not utilized. Perfluoro-n-octane was used as a postoperative tamponade for a mean of 16.4 days (range, 6-50 days).

RESULTS

The retina was reattached at the end of the procedure in all 16 cases. Redetachment occurred in only 1 (6.3%) of 16 cases.

CONCLUSION

Postoperative tamponade with perfluoro-n-octane may decrease the rate of redetachment in giant retinal tear repair compared with silicone oil or perfluorocarbon gas alone. We found no adverse effects directly attributable to perfluoro-n-octane.

Perfluorohexylethan (O62) as ocular endotamponade in complex vitreoretinal surgery

PURPOSE

To investigate the safety and performance of perfluorohexylethan (O62), a partially fluorinated alkane, as an intraoperative tool and heavy ocular endotamponade in complex vitreoretinal surgery.

PATIENTS AND METHODS

In a prospective clinical study, O62 was used as a postoperative ocular endotamponade in 11 eyes of 11 patients after pars plana vitrectomy for the following inferior pathologic conditions, proliferative vitreoretinopathy (n = 8), rhegmatogenous retinal redetachment with inferior tears (n = 1), and inferior giant tear (n = 2). The median duration of the O62 tamponade was 43 days (range, 17-55 days), and the median follow-up period after removal of the tamponade was 16 months.

RESULTS

The initial postoperative retinal attachment rate was 100%. In 7 of 11 eyes, the retina remained attached during the O62 tamponade and after its removal. During the tamponade period, no epiretinal membrane formation or macular pucker was observed in these seven eyes. Recurrent retinal detachments with proliferative vitreoretinopathy developed in 4 of 11 eyes under the tamponade. The median follow-up after removal of O62 was 16 months. A secondary cataract developed in all five phakic eyes. Severe emulsification was noted in all patients starting in the second week after surgery causing a decrease of visual acuity and a significantly reduced funduscopic view. In the early postoperative period, a marked inflammatory reaction in the anterior segment was seen in all patients. Slightly whitish precipitates were noted in 2 of 11 eyes. A transient increase in intraocular pressure up to 35 mmHg was observed in 2 of 11 eyes.

CONCLUSION

O62 showed good tamponade properties for the inferior retina over 6 weeks. However, its use as a postoperative retinal tamponade is limited by its severe emulsification propensity and unclear inflammatory potential.

Deposition of silicone oil droplets in the residual anterior lens capsule after vitrectomy and lensectomy in rabbits

AIM

To examine the histology of preserved anterior lens capsule in vitrectomised and lensectomised rabbit eyes with and without silicone oil tamponade.

METHODS

Forty adult Japanese albino rabbits received two port vitrectomy and lensectomy with or without silicone oil tamponade in one eye under both general and topical anaesthesia. Anterior lens capsule was preserved during operation. After healing intervals residual anterior capsule was histologically observed under light or electron microscopy.

RESULTS

Immediately after operation, cuboidal lens epithelial cells were observed on the posterior surface of the preserved anterior capsule. During healing intervals in eyes with or without silicone oil tamponade, regenerated lens structure of Sommerring's ring and fibrous tissue formed in the peripheral and central areas of the residual capsule, respectively. Ultrastructural observation revealed the presence of many vacuoles amid matrix accumulation on the posterior capsular surface, suggesting the deposition of emulsified silicone oil droplets.

CONCLUSION

Lens epithelial cells produce regenerated lenticular structure and fibrous tissue on the residual capsule following vitrectomy and lensectomy in rabbits. Silicone oil droplets formed by its emulsification deposit in extracellular matrix accumulated on the posterior surface of the anterior capsule. Emulsified silicone may potentially enhance opacification of residual anterior capsule following pars plana vitrectomy by silicone oil deposition and subsequent activation of lens epithelial cells.