Effect of gravity in long-term vitreous tamponade: in vivo investigation using perfluorocarbon liquids and semi-fluorinated alkanes

Short-Term Endotamponade With Perfluorocarbon Liquids for Giant Retinal Tear-Associated Retinal Detachment

Purpose: To investigate the use of short-term postoperative endotamponade with perfluorocarbon liquids (PFCLs) for the treatment of giant retinal tear-associated rhegmatogenous retinal detachment (RRD). Methods: This retrospective study evaluated patients who had 2-stage surgery, which entailed pars plana vitrectomy (PPV) completed in 2 consecutive surgeries spaced 5 days apart, during which a short-term tamponade with PFCL was used (Group 1), and patients who had conventional single-stage PPV with long-term silicone oil (SO) tamponade (Group 2). Results: The study comprised 74 eyes of 68 patients, 52 in Group 1 and 22 in Group 2. The mean (±SD) patient age at presentation was 48.19 ± 15.73 years. Of the cases, 18.9% had high myopia and 13.5% had previous trauma. The improvement in best-corrected visual acuity (BCVA) was significantly better in Group 1 than in Group 2 at all postoperative visits (P = .004, postoperative day [POD] 15; P = .002, POD 90; P = .00006, final follow-up). Anatomic success (an attached retina) was achieved in 82.7% of patients in Group 1 and in 72.7% of patients in Group 2 (P = .33). At the 6-month postoperative follow-up, 54.5% of patients and 50% of patients, respectively, had a logMAR BCVA of 1.00 or better (P = .721). The mean change in intraocular pressure from baseline was statistically significant in both groups (Group 1, P = .012; Group 2, P = .018). Conclusions: Anatomic and functional outcomes in giant retinal tear-associated RRD can be improved with short-term postoperative endotamponade with PFCLs.

Perfluorodecalin-based oxygenated emulsion as a topical treatment for chemical burn to the eye

Chemical injuries to the eye are emergencies with limited acute treatment options other than prompt irrigation and can cause permanent vision loss. We developed a perfluorodecalin-based supersaturated oxygen emulsion (SSOE) to topically deliver high concentration of oxygen to the eye. SSOE is manufactured in hyperbaric conditions and stored in a ready-to-use canister. Upon dispensation, SSOE rapidly raises partial oxygen pressure 3 times over atmospheric level. SSOE is biocompatible with human corneal cells and safe on mouse eyes in vivo. A single topical application of SSOE to the eye after alkali injury significantly promotes corneal epithelial wound healing, decreases anterior chamber exudation, and reduces optical opacity and cataract formation in mice. SSOE treatment reduces intraocular hypoxia, cell death, leukocyte infiltration, production of inflammatory mediators, and hypoxia-inducible factor 1-alpha signaling, thus hastening recovery of normal tissue integrity during the wound healing process. Here, we show that SSOE is an effective topical therapeutic in the acute treatment of ocular chemical injuries.

Vitreous Substitutes as Drug Release Systems

Vitreous substitutes are traditionally used to stabilize the retina after vitrectomy. In recent years, various approaches have been developed for using the vitreous substitute not only as a tamponade but also as a drug release system to tackle ocular diseases. This review provides an overview of the requirements for vitreous substitutes and discusses the current clinically applied as well as novel polymer-based vitreous substitutes as drug delivery systems, including their release mechanisms, efficiencies, challenges, and future perspectives.

Deciphering the Action of Perfluorohexyloctane Eye Drops to Reduce Ocular Discomfort and Pain

Perfluorohexyloctane (F6H8) eyedrops have been recently introduced in Europe as a product to treat dry eye disease, based on its ability to reduce tear film instability in Meibomian gland dysfunction and evaporative dry eye disease, although its mechanism of action is still unknown. In the present pilot study, we evaluated the effects of the ocular instillation of a single drop of commercial F6H8 eyedrops in 20 healthy humans (9 women/11 men), measuring: (a) Corneal surface temperature (CST) from infrared video images; (b) tear volume using phenol red threads; (c) blinking frequency; and (d) ocular surface sensations (cold, dryness, pricking, foreign body, burning, itching, gritty, eye fatigue, watering eyes, and light-evoked discomfort sensations; scored using 10 cm Visual Analog Scales), before and 5–60 min after F6H8 or saline treatment. CST decreased and tearing and blinking frequency increased significantly after F6H8 but not after saline solution. When applied unilaterally, CST decreased only in the F6H8-treated eye. No sensations were evoked after F6H8 or saline. The corneal surface temperature reduction produced by topical F6H8 does not evoke conscious ocular sensations but is sufficient to increase the activity of corneal cold thermoreceptors, leading to an increased reflex lacrimation and blinking that may relieve dry eye condition thus reducing ocular discomfort and pain.

Biocompatibility of intraocular liquid tamponade agents: an update

Intraocular liquids tamponade agents, such as perfluorocarbon liquids (PFCLs), semifluorinated alkanes (SFAs), silicone oils (SOs) and heavy silicone oils (HSOs), are a crucial intraoperative and/or postoperative tool in vitreoretinal surgery, in particular for the management of complex vitreoretinal diseases. However, their use is not without complications, which are potentially severe. Consequently, a growing interest has been devoted to the biocompatibility of these compounds and the adequacy of current regulations that should guarantee their safety. Obviously, an updated knowledge on research findings and potential risks associated to the use of intraocular liquid compounds is essential, not only for vitreoretinal surgeons, but also for any ophthalmologist involved in the management of patients receiving intraocular liquid tamponades. In light of this, the review provides a comprehensive characterisation of intraocular liquid tamponades, in terms of physical and chemical properties, current clinical use and possible complications. Moreover, this review focuses on the safety profile of these compounds, summarising the existing regulation and the available evidence on their biocompatibility.

Powder suspensions in non-aqueous vehicles for delivery of therapeutic proteins

Formulating biopharmaceuticals is a challenging task due to their complex and sensitive nature. Protein drugs are typically marketed either as an aqueous solution or as a lyophilizate. Usually aqueous solutions are preferred as neither drying nor reconstitution are required. But it may be unfeasible if the protein features low stability. An interesting alternative to avoid at least reconstitution are protein powder suspensions in non-aqueous vehicles. Such formulations combine the ready-to-use approach with the high protein stability in the solid state. Additionally, protein powder suspensions offer a potentially lower viscosity compared to aqueous solutions at high protein concentrations. Besides injection, other application routes might also benefit from the protein powder approach such as topical or inhalational delivery. Protein powders, which can be dispersed in the non-aqueous suspension vehicle, are usually prepared by spray-drying or freeze-drying with an additional milling step, but other techniques have also been described in literature. An ideal powder preparation technique results in minimum protein damage and yields particle sizes in the lower micrometre range and homogeneous particle size distribution enabling subcutaneous or intramuscular injection through hypodermic needles. As suspension vehicles traditional non-aqueous injectable liquids, such as plant oils, may be selected. But they show an inherent high viscosity, which can lead to unacceptable glide forces during injection. Furthermore, the vehicle should provide high product stability with respect to protein integrity and suspension resuspendability. This review will describe how proteins can be formulated as protein powder suspensions in non-aqueous vehicles for subcutaneous injection including potential vehicles, protein powder preparation techniques, protein and suspension physical stability, as well as the use in the field of high concentration protein formulations.

Influence of Perfluorocarbon Liquids on Peripapillary Retinal Nerve Fiber-Layer Thickness Following Pars Plana Vitrectomy with Silicone Oil-Based Endotamponade

Background

Inner retina–layer modifications after pars plana vitrectomy (PPV) can be objectively assessed through spectral domain optical coherence tomography (SD-OCT).

Methods

This study explored prospectively changes in retinal nerve-fiber layer (RNFL) thickness with SD-OCT in eyes undergoing PPV with silicone oil–based tamponade with and without use of perfluorocarbon liquids (PFCLs) during the early postoperative phase (up to 3 months) at the Research Institute of Ophthalmology, Egypt.

Results

Thirty patients were recruited who underwent PPV and silicone oil–based tamponade for either retinal detachment or diabetic retinopathy between April 2019 and September 2019. Mean RNFL thickness showed no significant change during follow-up at the first week (102.90±30.68 mm), 1 month (107.30±32.27), or three months (105.90±36.68; p=0.46, 0.68). There were significant correlations noticed between RNFL thinning and axial length of eyes, intraocular pressure, and use of PFCLs during the follow-up period.

Conclusion

The RNFL tends to change postvitrectomy, but not significantly. Careful examination and consistent follow-up is required for postvitrectomy patients with larger axial length and intraoperative PFCL use.

[Current importance of heavy fluids as intraoperative aids in vitreoretinal surgery]

A major milestone in the treatment of complex retinal detachment was the development of heavy fluids as intraoperative short-term tamponades. Since the introduction liquid perfluorocarbons and hydrofluorocarbons are particularly noteworthy. Irrespective of the suitability of the substances in principle, the purity during the manufacturing process is a decisive factor that determines possible side effects. Also, the direct exchange with silicone oil can lead to mixing with disadvantageous results. Retinal surgeons should be informed about the properties of the tamponades used. Despite all expectations, the heavy liquids could not become established compared to silicone oil as a long-term tamponade, which is why their domain is the short-term intraoperative use.

Perfluorodecalin Versus Densiron 68 Heavy Silicone Oil in the Management of Inferior Retinal Detachment Recurrence

BACKGROUND AND OBJECTIVE

To assess the efficacy of perfluorodecalin (PFD) or Densiron 68 heavy silicone oil (HSO) in the management of inferior complex retinal detachment recurrence.

PATIENTS AND METHODS

A retrospective, comparative consecutive case series study. Twenty-four eyes of 24 patients affected by inferior complex retinal detachment recurrence underwent pars plana vitrectomy with PFD or HSO as endotamponade. All patients recruited were affected by complicated inferior retinal detachments and had already undergone at least one vitreoretinal procedure. The primary endpoint was anatomical success with primary and secondary surgery. The secondary endpoints were functional outcome and inflammatory complications.

RESULTS

Out of 24 cases of inferior retinal detachment recurrence, 12 were tamponed with PFD (PFD group) and 12 with HSO (D68 group). Retinal reattachment rate at first surgery was 50% for the D68 group and 66.6% for the PFD group. Final reattachment rate after two or more surgical operations was 91.6% for the PFD group and 83.3% for the D68 group. Best-corrected visual acuity improved in both groups from a mean of 1.00 logMAR (20/200; standard deviation [SD]: 1) to 0.60 logMAR (20/80; SD: 0.3), and from a mean of 1.81 logMAR (20/2000; SD: 1.1) to a mean of 2.00 logMAR (20/2,000; SD:1) for the PFD and D68 groups, respectively.

CONCLUSION

Both the endotamponades used showed good results in solving inferior retinal detachment recurrence with a slightly better rate in the PFD group, but it was not statistically significant (P > .05). [Ophthalmic Surg Lasers Imaging Retina. 2019;50:274-280.].

Effects of perfluorooctane on the retina as a short-term and small amounts remnant in rabbits

AIM

To investigate changes in the rabbit retina after short-term and small amounts tamponade of perfluorooctane (PFO).

METHODS

New Zealand rabbits were used, and 48 eyes were randomly and evenly assigned into four different groups. The PFO groups received a residue of 0.1 mL of PFO for ophthalmic surgery or 0.1 mL of F-Octane at the end of surgery; eyes from the pars plana vitrectomy (PPV) group were filled with balanced salt solution and those having not received surgical intervention served as controls. Eyes were collected at 1, 4 and 12wk and studied.

RESULTS

Under a microscope, nuclear counts of the inner nuclear layer (INL) and outer nuclear layer (ONL) did not differ among the four groups at all time points; however, slight disarrangement of the ONL and occasional vacuolization of the INL were found in the inferior retina only at 12wk in two PFO groups. Four of the groups had similar results of Caspase-3 and TNF-α staining at all time points. Alternatively, IL-8 was increased in PFOa and PPV control groups at 4wk and in all three PPV groups at 12wk; also, the apoptotic index (%) was similarly increased in all three PPV groups at 4 and 12wk.

CONCLUSION

Both PFOs are well tolerated in rabbit eyes for up to 12wk, which suggests that they can be used safely as intraoperative tools or for short-term and small amounts tamponade after surgery.

Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: failure of another indirect cytotoxicity analysis

Aims

To report new information related to acute retinal toxicity of Bio Octane Plus, a mixture of 90% perfluorooctane (PFO) and 10% perfluorohexyloctane.

Methods

This retrospective, descriptive case series reports the occurrence of acute retinal toxicity after vitreoretinal surgery in which Bio Octane Plus (batch number 1605148) was used as an endotamponade. Cytotoxicity biocompatibility tests and chemical analyses by Fourier-transformed infrared (FTIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) of the presumed toxic product were performed.

Results

Four patients presented with acute severe visual loss after uneventful ocular surgery assisted by Bio Octane Plus (batch number 1605148) as endotamponade. Patients experienced extensive retinal vascular occlusion leading to retinal and optic nerve atrophy. The viability of ARPE-19 cells directly exposed to the suspect batch for 30 min was 0%. The agarose overlay method used by the manufacturer according to European Union regulations and International Organization for Standardization (ISO) International Standards failed to detect toxicity. FTIR spectroscopy showed small differences between the non-toxic and toxic batches. GC-MS analysis showed the presence of bromotributyl stannane (whose toxicity was demonstrated in the dose–response curve) only in the toxic batch of Bio Octane Plus.

Conclusion

This is the third report of retinotoxicity due to PFO in 4 years. The clinical profiles may be missed as they resemble other postsurgical complications; therefore, more cases worldwide could have gone unreported. Protocols to determine cytotoxicity of intraocular medical devices and approved by the ISO International Standards based on indirect methods have failed and should be revised to ensure safety.

Recent Progress in Using Biomaterials as Vitreous Substitutes

Vitreous substitutes are crucial adjuncts during vitreo-retinal surgery for retinal diseases such as complicated retinal detachment, macular holes, complications of diabetic retinopathy, and ocular trauma involving posterior segment. In retinal detachment surgery, an internal tamponade agent is required to provide internal pressure for reattachment of the detached neurosensory retina. Current available options serve only as a temporary surgical adduct or short-term solution and are associated with inherent problems. Despite many years of intensive research, an ideal vitreous substitute remains elusive. Indeed, the development of an ideal vitreous substitute requires the concerted efforts of synthetic chemists and biomaterial engineers, as well as ophthalmic surgeons. In this review, we propose that polymeric hydrogels present the future of artificial vitreous substitutes due to its high water composition, optical transparency, and rheological properties that closely mimic the natural vitreous. In particular, thermosensitive smart hydrogels, with reversible sol to gel change, have emerged as the material class with the most potential to succeed as ideal vitreous substitutes, facilitating easy implementation during surgery. Importantly, these smart hydrogels also display potential as efficacious drug delivery systems.

Vitreous substitutes: the present and the future

Vitreoretinal surgery has advanced in numerous directions during recent years. The removal of the vitreous body is one of the main characteristics of this surgical procedure. Several molecules have been tested in the past to fill the vitreous cavity and to mimic its functions. We here review the currently available vitreous substitutes, focusing on their molecular properties and functions, together with their adverse effects. Afterwards we describe the characteristics of the ideal vitreous substitute. The challenges facing every ophthalmology researcher are to reach a long-term intraocular permanence of vitreous substitute with total inertness of the molecule injected and the control of inflammatory reactions. We report new polymers with gelification characteristics and smart hydrogels representing the future of vitreoretinal surgery. Finally, we describe the current studies on vitreous regeneration and cell cultures to create new intraocular gels with optimal biocompatibility and rheological properties.

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.

Colored perfluorocarbon liquids as novel intraoperative tools

BACKGROUND

Perfluorocarbon liquids (PFCLs) are used as intraoperative tools to stabilize the retina during vitreoretinal surgeries. Their use would be much facilitated if PFCLs were colored and not transparent. We describe the development of a colored PFCL for vitreoretinal surgeries.

METHODS

Perfluorohexyloctan (F6H8) was colored by adding a blue, biocompatible anthraquinone dye, and then mixed with perfluorodecalin (PFD) or perfluorooctane (PFO) at different volume percentages. The thus-obtained colored PFCLs were incubated with lens, lens capsule, vitreous body, and retina of enucleated porcine eyes for staining purpose and analyzed microscopically. To analyze possible interactions between colored PFCLs and silicone oil, colored PFCLs were exchanged to BSS and silicone oil respectively in enucleated pig eyes.

RESULTS

By mixing different volume% of colored F6H8 with perfluorodecalin (PFD) or perfluorooctane (PFO), colored PFCLs of different density and staining intensity were obtained. Cornea, lens, lens capsule, vitreous, and retina showed no signs of staining after incubation with colored PFCLs for 10 min. Colored PFCLs were transparent despite intense coloring, thus allowing a clear visibility of the underlying tissue. Immediately after instillation of silicone oil, the colored PFCL bubble was well-defined, and colored PFCL was easily aspirated. After 5 minutes reaction time, considerable diffusion of the dye from the PFCL bubble into the silicone oil was observed.

CONCLUSIONS

The staining intensity can be varied according to the volume% of the colored F6H8 phase. Colored PFCL is clearly visible when installed in the vitreous cavity of a pig eye, and can easily be removed. It does not stain the intraocular tissues in pig eyes. Colored PFCL can be exchanged with silicone oil. But a time-dependent diffusion of the dye into the silicone oil was observed in pig eyes, indicating that the contact should be limited.

[Perfluorocarbon liquids and vitreoretinal surgery in 2011]

Perfluorocarbon liquids (PFCLs) are one of the most innovative recent tools for vitreoretinal surgery. PFCLs are characterized by their number of carbon atoms, which has an impact on the density, viscosity, surface tension, vapor pressure, the boiling point, and the refraction index. PFCLs are routinely used because of their high gravity (double that of water) and their low viscosity. Furthermore, they are immiscible in water, optically clear with refraction indices similar to that of water, allowing visualization of an interface between the PFCL and saline. The use of intravitreally injected liquid PFCLs as adjunctive agents to vitreoretinal surgery plays an important role in facilitating retinal reattachment, especially in cases of giant retinal tear, trauma, and/or proliferative vitreoretinopathy. PFCLs are also used as intraoperative instruments to re-establish intraocular volume, assist in separating membranes adherent to the retina (in proliferative diabetic retinopathy, for example), and manage the dislocated crystalline lens and intraocular lens.

Heavy silicone oil versus standard silicone oil in as vitreous tamponade in inferior PVR (HSO Study): interim analysis

PURPOSE

The Heavy Silicone Oil versus Standard Silicone Oil Study (HSO study) is designed to answer the question whether a heavier-than-water tamponade improves the prognosis of eyes with proliferative vitreoretinopathy (PVR) of the lower retina.

METHODS

The HSO Study is a multicentre, randomized, prospective, controlled clinical trial stratified by surgeon comparing two endotamponades within a two-arm parallel-group design. Patients with inferiorly and posteriorly located PVR grade C-A6 were randomized to either HSO or standard silicone oil as a tamponading agent. The main end-point criteria are complete retinal attachment at 12 months and change in visual acuity (VA) 12 months postoperatively compared to the preoperative VA.

RESULTS

Forty-six patients treated with HSO were compared to 47 patients treated with standard silicone oil. There was no difference among the groups regarding baseline data. Three patients in the HSO and five patients in the standard silicone oil group fulfilled intraoperative exclusion criteria. There was no significant difference between both groups regarding anatomical success. Neither noninferiority nor superiority was shown with regard to final acuity.

CONCLUSIONS

The HSO Study is the first randomized prospective clinical trial to compare heavy and standard silicone oil in patients with PVR of the lower retina. The intermediate results failed to demonstrate superiority of a heavy tamponade.

Vitreous substitutes: a comprehensive review

Vitreoretinal disorders constitute a significant portion of treatable ocular disease. Advances in vitreoretinal surgery have included the development and characterization of suitable substitutes for the vitreous. Air, balanced salt solutions, perfluorocarbons, expansile gases, and silicone oil serve integral roles in modern vitreoretinal surgery. Vitreous substitutes vary widely in their properties, serve different clinical functions, and present different shortcomings. Permanent vitreous replacement has been attempted with collagen, hyaluronic acid, hydroxypropylmethylcellulose, and natural hydrogel polymers. None, however, have proven to be clinically viable. A long-term vitreous substitute remains to be found, and recent research suggests promise in the area of synthetic polymers. Here we review the currently available vitreous substitutes, as well those in the experimental phase. We classify these compounds based on their functionality, composition, and properties. We also discuss the clinical use, advantages, and shortcomings of the various substitutes. In addition we define the ideal vitreous substitute and highlight the need for a permanent substitute with long-term viability and compatibility. Finally, we attempt to define the future role of biomaterials research and the various functions they may serve in the area of vitreous substitutes.

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.

In vitro emulsification assessment of new silicone oils

Aim

To investigate whether the emulsification of conventional silicone oils can be reduced by adding small amounts of silicone molecules of a very long chain length.

Methods

Siluron 1000, Siluron 2000, Siluron 5000, Acri.Sil-Ol 5000, Oxane 5700, Densiron 68 LV, Densiron 68 and Densiron 68 HV (0.5 ml) were each tested along with either plasma or serum (0.5 ml) in a glass cuvette. Emulsification was induced by sonication and documented by photography. The total area of emulsified oil was assessed using the ImageJ software.

Results

The addition of small amounts of very-long-chain silicone molecules significantly reduced the emulsification for 1000 cSt silicone oil (Siluron 2000) and for 1000 cSt silicone oil with an admixture of F6H8 (Densiron 68 HV).

Conclusion

New low-viscosity silicone oils show a reduced emulsification similar to that of 5000 cSt oils. In future, it may be possible to avoid using 5000 cSt oils. The findings may foster silicone oil surgery in general, and in particular the application of small-incision techniques.

[New developments in retinal detachment surgery]

The initial surgery is one of the most important factors influencing the anatomic and functional outcome of retinal detachment surgery. With the continual modifications in vitrectomy techniques, the strategy in primary vitrectomy surgery is also changing. Recent developments are the use of 25- and 23-gauge trocar systems and new surgical techniques without the use of perfluorcarbons or gas or silicone oil tamponade. In addition, heavy silicone oils are now entering routine clinical use, especially for proliferative vitreoretinopathy (PVR) redetachments of the lower fundus periphery. Regarding adjunct pharmacologic therapy, daunorubicin and 5-fluorouracil/low molecular weight heparin have been found to improve the results of patients with PVR or at risk for PVR.