Air as Tamponade for Retinal Detachments

Expansile gas concentration in primary pseudophakic retinal detachment repair, effect on intraocular pressure and outcomes; the Manchester Pseudophakic Retinal Detachment Study

PURPOSE

To investigate the effect of isovolumetric and expansile gas tamponade concentrations on single surgery anatomical success (SSAS) and day 1 intraocular pressure (IOPD1) following pars plana vitrectomy (PPV) for mild-moderate complexity primary pseudophakic rhegmatogenous retinal detachment (PRD).

METHODS

We conducted a single-centre retrospective continuous and comparative study on eyes that had undergone small-gauge PPV using isovolumetric versus expansile gas for PRD repair between 2011 and 2020 at a single tertiary vitreoretinal centre in UK. We performed propensity score matching (PSM) using preoperative findings as covariates to account for relevant confounders. Significant risk factors such as proliferative vitreoretinopathy C or giant retinal tears were excluded.

RESULTS

From 456 eyes, PSM analysis matched 240 eyes with 120 in each group. The median (interquartile range) follow-up was 96 (59 to 218) days. The SSAS was 229/240 (95.8%) overall; 115/120 (95.8%) and 114/120 (95.0%) in isovolumetric and expansile groups, respectively (p = 1.000). Relative to the isovolumetric group, the expansile group had lower proportion of eyes with IOP ≤ 21 mmHg (odds ratio, 95% confidence interval, 0.40 [0.23-0.68], p < 0.001); but significantly higher number of eyes with IOP ≥ 22 mmHg (2.53 [1.48-4.34], p < 0.001), ≥ 25 mmHg (2.77 [1.43-5.33], p < 0.001), ≥ 30 mmHg (2.90 [1.28-6.58], p = 0.006) and ≥ 40 mmHg (p = 0.029, isovolumetric: 0 [0%] vs expansile group: 6 [5%]). There was only one case of hypotony (≤ 5 mmHg) 1/240 (0.4%) which occurred in the expansile group.

CONCLUSIONS

Expansile gas concentration does not impact SSAS but is associated with significantly raised IOPD1 with no reduction in hypotony rates following PPV for primary PRD.

The use of fluorinated gases and quantification of carbon emission for common vitreoretinal procedures

PURPOSE

To report the contribution to carbon dioxide equivalent mass [CO2EM] of various types of VR surgery performed across three tertiary referral centres, according to their indication and fluorinated gas used. We secondarily reported on the difference in tamponade choice, and CO2EM between the different centres.

MATERIALS

Retrospective, continuous, comparative multicentre study of all procedures using fluorinated gases between 01/01/17-31/12/20 at the Manchester Royal Eye Hospital and Birmingham and Midland Eye Centre, and between 01/01/19-31/12/2020 at the University Hospitals Coventry and Warwickshire.

RESULTS

Across 4877 procedures, the use of fluorinated gases produced 284.2 tonnes (71.2 tonnes annually) CO2EM; an annual consumption of 30,330 l of gasoline. Rhegmatogenous-retinal-detachment (RRD) and macular hole repair had the highest CO2EM by indication, accounting for 191.4 tonnes CO2EM (67.3%) and 28.6 tonnes CO2EM (10.1%); a mean 60.0 kg and 32.0 kg of CO2EM produced per surgery respectively. The use of fluorinated gases and their respective CO2EM contributions were significantly different across all three centres (p < 0.001) for all indications. SF6, despite being used in 1883 procedures (38.6%), contributed to 195.5 tonnes CO2EM (68.8%). Relative to C2F6, procedures using C3F8 and SF6 produced 1.9 and 4.4 times more CO2EM.

CONCLUSION

We demonstrated that SF6 causes significantly higher carbon emissions relative to C2F6 and C3F8 with RRD and macular hole repair having the greatest environmental impact. We also reported large variations between different large VR centres in fluorinated gas use, and therefore in carbon emission contributions depending on indications for surgery. Evidence-based protocols might help in making VR surgery "greener".

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.

The cause of redetachment after vitrectomy with air tamponade for a cohort of 1715 patients with retinal detachment: an analysis of retinal breaks reopening

BACKGROUND

To investigate the prevalence and predictors of retinal breaks reopening after vitrectomy with air tamponade in rhegmatogenous retinal detachment (RRD).

METHODS

A retrospective cohort study was conducted in Shanghai General Hospital. Chart review was performed among 1715 patients with primary RRD who received pars plana vitrectomy (PPV) with air tamponade as initial management. Patients were followed up for recurrence. The clinical features of the eyes with retinal breaks reopening were recorded. Logistic regression was constructed to investigate the predictors for breaks reopening.

RESULTS

A total of 137 (7.99%) patients had recurrent retinal detachment after PPV with air tamponade. The causes of surgery failure included new or missed retinal breaks (48.9%), reopening of original tears (43.8%) and proliferative vitreoretinopathy (7.3%). The median time to recurrence for the patients with breaks reopening was 18.0 days. Multivariate logistic regression indicated that the presence of retinal break(s) ≥ 1.5 disc diameters (DD) (odds ratio [OR]: 2.68, 95% confidence interval [CI]: 11.04-6.92, P = 0.041), and shorter period for restricted activities (OR: 0.94, 95% CI: 0.89-0.99, P = 0.020) were the independent predictors for breaks reopening.

CONCLUSIONS

Breaks reopening is an important cause for retinal redetachment after PPV with air tamponade in primary RRD. The first 2-4 weeks after surgery is the "risk period" for breaks reopening. Special attention should be paid for patients with retinal break(s) ≥ 1.5 DD. A prolonged period for restricted activities is recommended.

Air versus fluorinated gas tamponades in pars plana vitrectomy treatment for primary rhegmatogenous retinal detachment

PURPOSE

To compare the treatment success of air with fluorinated gas (20% SF₆ or 14% C₃ F₈ ) tamponade in pars plana vitrectomy for primary rhegmatogenous retinal detachment.

METHODS

A retrospective cohort study comprised of 1023 consecutive primary retinal detachment cases between 2014 and 2020. We employed a univariate multivariable binary logistic regression model.

RESULTS

We used intraocular gas tamponades in 872 cases with PVR grade B or lower: air tamponade was used in 414 eyes and 458 eyes were treated with a type of fluorinated gas tamponade. There was no significant difference in the type of tamponade with regard to the re-detachment rate (95% CI -1.0% and 4.1%). Additionally, also in the subgroup of rhegmatogenous retinal detachments with inferior located retinal defects we found no significant difference between the two types of tamponade (p = 0.54 Fisher's exact). The multivariable model, which included tamponade, PVR grade, a retinal detachment involving the 6 o'clock position and age as covariates, also showed no significant effect of tamponade choice on treatment success (OR 0.5, 95% 0.2-1.0, p = 0.10).

CONCLUSION

We found no difference in treatment success with air tamponade versus fluorinated gas tamponades in the repair of primary retinal detachments, this also includes inferiorly located retinal tears and detachments.

Clinical characteristics of primary pars plana vitrectomy combined with air filling for rhegmatogenous retinal detachment

To detect the prognostic factors associated with initial reattachment after primary pars plana vitrectomy (PPV) with air tamponade for rhegmatogenous retinal detachment (RRD). We retrospectively reviewed 92 eyes of 92 patients with RRD. All eyes underwent PPV with air tamponade and a follow-up of at least 6 months. Initial anatomical success was defined as reattachment of the retina by a single operation. We performed univariate analysis to detect the presence of any difference between eyes with a successful initial reattachment and those that failed. We also performed multivariate logistic regression analysis to assess the influence of each preoperative factor on initial success. The rate of initial reattachment success was 93.5%. The percentage of retinal detachment involving the inferior quadrants in the initial success group was less than that in the initial failure group, and the difference was statistically significant (P = 0.043). There were no significant differences noted for other factors, such as symptom duration (P = 0.078) or location of retinal breaks (P = 0.065). Multiple logistic regression analysis using preoperative factors indicated that older age (odds ratio, 0.90; 95% confidence interval, 0.82–0.97; P = 0.010) and non-involvement of inferior quadrants (odds ratio, 9.90; 95% confidence interval, 1.36–71.92; P = 0.023) were significantly associated with initial success. PPV combined with air may be an effective treatment for some simple RRDs (proliferative vitreoretinopathy [PVR] grade ≤ C1). Non-involvement of the inferior quadrants and older age at presentation are associated with a greater likelihood of anatomic success. The volume of air in the eye after surgery is also very important, which may also affect the reduction of retinal detachment.

Environmental effect of air versus gas tamponade in the management of rhegmatogenous retinal detachment VR surgery: A multicentre study of 3,239 patients

Purpose

To report the potential reduction of carbon emissions by utilising air-tamponade (AT), where possible, instead of fluorinated gases in the management of rhegmatogenous retinal detachment (RRD). We compared the carbon CO₂ emissions produced at two large tertiary referral vitreoretinal (VR) centres where RRD are exclusively repaired using fluorinated gases to a tertiary VR mass of each gas used according to the Intergovernmental Panel on Climate Change.

Materials and methods

Retrospective, continuous, comparative multicentre study of all procedures using fluorinated gases between 01/01/17-31/12/20 at the Manchester Royal Eye Hospital (MREH) and Birmingham and Midland Eye Centre (BMEC), and between 01/01/19-31/12/2020 at the University Hospitals Coventry and Warwickshire (UHCW).

Results

We report on 3,239 (SF₆:1,415 [43.7%], C₂F₆:1,235 [38.1%], C₃F₈:541 [16.7%], Air:48 [1.5%]) procedures. UHCW and BMEC utilise single use 30ml and 75ml cannisters, respectively and MREH use multi-use gas cylinders. UHCW used AT in 48 (70%) of RRD repairs. Mean equivalent mass CO₂/patient was MREH:115.9kg, BMEC:7.9kg and UHCW:1.9kg. If assuming all centres used 30ml cannisters, the mean equivalent mass CO₂/patient was MREH:3.5 kg, BMEC:3.1kg and UHCW:1.9kg. AT enabled UHCW to greatly reduce the need for the most environmentally damaging SF₆ gas, leading to lower CO₂ emissions by 47.0% and 41.1% compared to MREH and BMEC, respectively.

Conclusion

We demonstrate how AT vs. the fluorinated gases can reduce in carbon footprint in the management of RRD. Further studies are required to determine the most ‘environment-friendly’ intraocular tamponade without compromising patient outcomes centre that also routinely employs AT in selected RRD cases.

Retinal Detachment Repair With Vitrectomy: Air Tamponade Integration to a Vitreoretinal Service, Comparison With Gas Tamponade, and Literature Review

BACKGROUND AND OBJECTIVE

Rhegmatogenous retinal detachment (RRD) repair by pars plana vitrectomy and gas tamponade (GT) has significant clinical and quality-of-life impacts compared with repair by short-acting air tamponade (AT). With AT, most authors minimize cryotherapy because of prolonged chorioretinal scar formation and use perfluorocarbon to maximize subretinal fluid drainage; this deviates from traditional technique, which discourages popularization of AT.

PATIENTS AND METHODS

Prospective 12-month study from January to December 2019 of all primary macula-on RRD cases. Patients fulfilling the inclusion criteria for the Pneumatic Retinopexy Versus Vitrectomy for Retinal Detachment Trial received AT and otherwise were assigned to receive GT.

RESULTS

Forty-six patients were enrolled: 22 (48%) receiving AT and 24 (52%) receiving GT. The primary success rate of AT was 21 (95%) and the primary success rate of GT was 23 (96%), with 100% final success. Cryopexy was used in 64% of AT cases and 58% of GT cases. Cataract surgery was required less when AT was used (1 [6%]) than when GT was used (3 [21%]). AT was used in 48% of primary macula-on RRD and 27% of all primary RRD cases.

CONCLUSIONS

AT has visual and anatomical outcomes comparable to those of GT with conventional vitrectomy techniques, with faster postoperative rehabilitation enabling a swift return to normal daily activities. [Ophthalmic Surg Lasers Imaging Retina. 2022;53:87-95.].

Recent Advances in Hydrogels: Ophthalmic Applications in Cell Delivery, Vitreous Substitutes, and Ocular Adhesives

With the prevalence of eye diseases, such as cataracts, retinal degenerative diseases, and glaucoma, different treatments including lens replacement, vitrectomy, and stem cell transplantation have been developed; however, they are not without their respective shortcomings. For example, current methods to seal corneal incisions induced by cataract surgery, such as suturing and stromal hydration, are less than ideal due to the potential for surgically induced astigmatism or wound leakage. Vitrectomy performed on patients with diabetic retinopathy requires an artificial vitreous substitute, with current offerings having many shortcomings such as retinal toxicity. The use of stem cells has also been investigated in retinal degenerative diseases; however, an optimal delivery system is required for successful transplantation. The incorporation of hydrogels into ocular therapy has been a critical focus in overcoming the limitations of current treatments. Previous reviews have extensively documented the use of hydrogels in drug delivery; thus, the goal of this review is to discuss recent advances in hydrogel technology in surgical applications, including dendrimer and gelatin-based hydrogels for ocular adhesives and a variety of different polymers for vitreous substitutes, as well as recent advances in hydrogel-based retinal pigment epithelium (RPE) and retinal progenitor cell (RPC) delivery to the retina.

Efficacy of PPV Combined with Air Tamponade for Treatment of Inferior Retinal Breaks

Purpose

To observe the efficacy and safety of pars plana vitrectomy (PPV) combined with filtered air tamponade in the treatment of rhegmatogenous retinal detachment (RRD) with inferior retinal breaks.

Methods

This retrospective study included 20 patients (20 eyes) with inferior retinal breaks in RRD; all underwent PPV combined with filtered air tamponade. Preoperative examinations included BCVA, IOP, anterior segment, fundus and locations, numbers, and sizes of retinal breaks and ocular B-mode ultrasonography. Postoperative examinations included BCVA, IOP, residual gas volume, retinal reattachment, and complications.

Results

After follow-up for 1 year, the primary retinal reattachment rate was 95% and the final reattachment rate was 100%. Pre- and postoperative BCVA averaged 1.51 ± 0.63 and 0.97 ± 0.58 logMAR, respectively; the difference was statistically significant (P < 0.001). Average pre- and postoperative IOP were not statistically different. The average volume of residual gas on the first day after the surgery was 77.5%; the gas was absorbed in all patients within 2 weeks; no significant postoperative complications were observed.

Conclusion

PPV combined with filtered air tamponade is a safe and effective treatment for RRD with inferior retinal breaks. Notably, the retinal reattachment rate is high, gas absorption is rapid, and incidence of complications is low.

Current Situation and Challenges in Vitreous Substitutes

Vitreo-retinal disorders constitute a significant portion of treatable ocular diseases. These pathologies often require vitreo-retinal surgery and, as a consequence, the use of vitreous substitutes. Nowadays, the vitreous substitutes that are used in clinical practice are mainly divided into gases (air, SF₆ , C₂ F₆ , C₃ F₈ ) and liquids (perfluorocarbon liquids, silicone oils, and heavy silicone oils). There are specific advantages and drawbacks to each of these, which determine their clinical indications. However, developing the ideal biomaterial for vitreous substitution continues to be one of the most important challenges in ophthalmology, and a multidisciplinary approach is required. In this sense, recent research has focused on the development of biocompatible, biodegradable, and injectable hydrogels (natural, synthetic, and smart), which also act as medium and long-term internal tamponade agents. This comprehensive review aims to cover the main characteristics and indications for use of the extensive range of vitreous substitutes that are currently used in clinical practice, before going on to describe the hydrogels that have been developed recently and which have emerged as promising biomaterials for vitreous substitution.

Substitutes and Colloidal System for Vitreous Replacement and Drug Delivery: Recent Progress and Future Prospective

Vitreoretinal surgeries for ocular diseases such as complicated retinal detachment, diabetic retinopathy, macular holes and ocular trauma has led to the development of various tamponades over the years in search for an ideal vitreous substitute. Current clinically used tamponade agents such as air, perfluorocarbons, silicone oil and expansile gases serve only as a short-term solution and harbors various disadvantages. However, an ideal long-term substitute is yet to be discovered and recent research emphasizes on the potential of polymeric hydrogels as an ideal vitreous substitute. This review highlights the recent progress in the field of vitreous substitution. Suitability and adverse effects of various tamponade agents in present day clinical use and biomaterials in the experimental phase have been outlined and discussed. In addition, we introduced the anatomy and functions of the native vitreous body and the pathological conditions which require vitreous replacement.

Vitreous substitutes: An overview of the properties, importance, and development

Vitreous or vitreous humor is a complex transparent gel that fills the space between the lens and retina of an eye and acts as a transparent medium that allows light to pass through it to reach the photoreceptor layer (retina) of the eye. The vitreous humor is removed in ocular surgery (vitrectomy) for pathologies like retinal detachment, macular hole, diabetes-related vitreous hemorrhage detachment, and ocular trauma. Since the vitreous is not actively regenerated or replenished, there is a need for a vitreous substitute to fill the vitreous cavity to provide a temporary or permanent tamponade to the retina following some vitreoretinal surgeries. An ideal vitreous substitute could probably be left inside the eye forever. The vitreous humor is transparent, biocompatible, viscoelastic and highly hydrophilic; polymeric hydrogels with these properties can be a potential candidate to be used as vitreous substitutes. To meet the tremendous demand for the vitreous substitute, many scientists all over the world have developed various kinds of vitreous substitutes or tamponade agent. Vitreous substitutes, whatsoever developed till date, are associated with several advantages and disadvantages, and there is no ideal vitreous substitute available till date. This review highlights the polymer-based vitreous substitutes developed so far, along with their advantages and limitations. The gas-based and oil-based substitutes have also been discussed but very briefly.

Polymeric hydrogels as a vitreous replacement strategy in the eye

Vitreous endo-tamponades are commonly used in the treatment of retinal detachments and tears. They function by providing a tamponading force to support the retina after retina surgery. Current clinical vitreous endo-tamponades include expansile gases (such as sulfur hexafluoride (SF₆) and perfluoropropane (C₃F₈)) and also sislicone oil (SiO). They are effective in promoting recovery but are disadvantaged by their lower refractive indices and lower densities as compared to the native vitreous, resulting in immediate blurred vision after surgery and necessitating patients to assume prolonged face-down positioning respectively. While the gas implants diffuse out over time, the SiO implants are non-biodegradable and require surgical removal. Therefore, there is much demand to develop an ideal vitreous endo-tamponade that can combine therapeutic effectiveness with patient comfort. Polymeric hydrogels have since attracted much attention due to their favourable properties such as high water content, high clarity, suitable refractive indices, suitable density, tuneable rheological properties, injectability, and biocompatibility. Many design strategies have been employed to design polymeric hydrogel-based vitreous endo-tamponades and they can be classified into four main strategies. This review seeks to analyse these various strategies and evaluate their effectiveness and also propose the key criteria to design successful polymeric hydrogel vitreous endo-tamponades.

Vitrectomy with air tamponade for surgical repair of rhegmatogenous retinal detachment by eye position guided fluid-air exchange

AIM

To observe the efficacy and safety of pars plana vitrectomy (PPV) with eye position guided fluid-air exchange (FAX) and air tamponade in the treatment of rhegmatogenous retinal detachment (RRD).

METHODS

RRD patients without severe proliferative vitreoretinopathy (PVR) C1 or more were enrolled. All patients underwent PPV combining with air tamponade. During operation, the primary retinal break(s) were placed at lower site and subretinal fluid was aspirated through the break(s) at the same time when eye position guided FAX was proceeding. Sufficient laser spots were made to seal the retinal break(s) after FAX, and filtered air was left in vitreous cavity as tamponade agent finally. The main outcomes were primary and final success rates, best corrected visual acuity (BCVA), and the secondary outcomes were rate of postoperative cataract surgery and high intraocular pressure.

RESULTS

A total of 37 eyes (20 males and 17 females) with a follow-up time of ≥6mo were included. The range of RRD was 5.6±1.8h, and the number of retinal breaks was 1.9±1.2. The breaks located at inferior quadrants (between 3:00 and 9:00) in 5 cases (13.5%), and both superior and inferior breaks were found in 3 cases (8.1%). A total of 25 cases (67.6%) with macular detached involvement, 9 cases (24.3%) with intraocular lens, and 8 patients (21.6%) were treated with phacoemulsification and intraocular lens implantation together. The success rate of primary retinal reattachment was 100% (37/37). At 6mo postoperatively, BCVA (logMAR) was increased from 1.13±1.07 to 0.23±0.15 (P<0.001). Phacoemulsification combined with intraocular lens implantation was performed in 2 patients (5.4%), and one of them underwent macular epiretinal membrane peeling in addition (2.7%). Furthermore, high intraocular pressure was found in 4 cases (10.8%).

CONCLUSION

PPV with air tamponade by eye position guided FAX can achieve a high reattachment success rate in the management of patients with RRD, and it has the advantages of short postoperative prone time and fewer operative complications.

SURGICAL OUTCOMES OF 25-GAUGE PARS PLANA VITRECTOMY USING AIR AS AN INTERNAL TAMPONADE FOR PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT

PURPOSE

To report surgical outcomes of 25-gauge pars plana vitrectomy using air as an internal tamponade for patients with primary rhegmatogenous retinal detachment (RRD).

METHODS

A retrospective clinical study of 59 eyes of 59 consecutive patients presented with primary RRD at the Beijing Tongren Eye Center in China. From August 2016 to May 2018, medical records of the patients who underwent 25-gauge pars plana vitrectomy with air tamponade for RRD were reviewed. The main outcome measures were primary and final anatomical success (retinal re-attachment) rates, and postoperative complications.

RESULTS

Of the 59 patients, aged 54.47 ± 11.81 years, 31 (52.5%) were men. Vitrectomy was performed 3 to 40 (averaged 16.98 ± 10.17) days after the onset of symptoms, and the mean follow-up period was 12.90 ± 5.92 months (ranging 6.07-26.10 months). Forty-two eyes (71.2%) had RRD with retinal breaks in the superior half of the retina, and the mean number of retinal breaks was 1.75 ± 0.94. Three eyes (5.1%) had RRD with giant retinal tears. Of the 59 eyes, 35 (59.3%) had RRD with inferior quadrants involved. Proliferative vitreoretinopathy (PVR) gradings were C1 in 2 (3.4%) eyes and B or below in 57 (96.6%) eyes. The primary and final anatomical success rates were 94.9% (56/59) and 98.3% (58/59), respectively. Of the three eyes which developed re-detachment of the retina, one eye had postoperative progression of PVR and two eyes were RRD associated with macular hole in high myopia. Postoperative complications included 5 eyes (8.5%) with serous choroidal detachment within 3 days after surgery and 4 eyes (6.8%) with macular epiretinal membrane formation 1 to 8 months after surgery. Secondary cataract surgery was performed in 13 of the 53 phakic eyes (24.5%) during follow-up.

CONCLUSION

Small-gauge pars plana vitrectomy with air tamponade may be effective in treating selected cases of relatively simple primary RRD. Additional studies are needed to verify the efficacy of this surgical approach for more complicated cases such as those with giant retinal tears.

Ability of Nonswelling Polyethylene Glycol-Based Vitreous Hydrogel to Maintain Transparency in the Presence of Vitreous Hemorrhage

Purpose

Postoperative vitreous hemorrhage is a vision-impacting complication of vitrectomy. This preclinical in vitro study assessed the potential ability of a nonswelling polyethylene glycol-based artificial vitreous hydrogel to maintain transparency in the vitreous cavity in the presence of vitreous hemorrhage.

Methods

Samples (1 mL) of diluted blood at concentrations of 0.1%, 0.25%, 0.5%, and 1.25% were added to 1 mL samples of polymerized hydrogel in cuvettes (gel + blood group); 2 mL samples of diluted blood at the same concentrations were prepared as controls (blood only group). Spectral transmission curves for the hydrogel (gel + blood group) and diluted blood (blood only group) were obtained before and on days 1, 2, 5, 7, 14, and 28 of the experiment. Between-group comparisons were made using the Student's t-test. The percentage of transmittance in the visible light spectrum (400–700 nm) was measured at each time point.

Results

Mean light transmittance was maintained at >90% until day 7 in the gel + blood group and was significantly greater in the gel + blood than in the blood only groups in samples containing blood diluted to 0.25%, 0.5%, and 1.25% during the 28-day study period (P < 0.05).

Conclusions

A nonswelling polyethylene glycol-based artificial vitreous hydrogel maintained high optical transparency in the presence of blood through the study period. Injection of this hydrogel into the vitreous cavity at the end of surgery might help to prevent or mitigate vitreous hemorrhage-associated postoperative visual loss.

Translational Relevance

The hydrogel may prevent visual loss due to postoperative vitreous hemorrhage.

Air tamponade and without heavy liquid usage in pars plana vitrectomy for rhegmatogenous retinal detachment repair

AIM

To report the results of rhegmatogenous retinal detachment (RRD) repair after pars plana vitrectomy (PPV) without operative use of heavy liquid, and utilizing air tamponade in selected cases.

METHODS

RRD patients without severity of proliferative vitreoretinopathy C₂ or more underwent PPV without operative use of heavy liquid, and utilizing air tamponade were consecutively enrolled. Alternative postoperative facedown position or lateral position was required for 3-5d.

RESULTS

Totally 36 eyes of 36 patients (24 males, 66.7%) aged 53.8±10.9y underwent this modified surgery. The mean number of retinal break was 2.1±1.3. Most of the eyes (29, 80.6%) had retinal detachment involving more than one quadrant. Twenty-two (61.1%) eyes with cataract had combined phacoemulsification and intraocular lens implantation. The mean follow up time was 4.6±1.8mo. Two eyes with retinal redetachment underwent a second retinal repair surgery with silicone oil tamponade, yielding the primary reattachment rate to 94.4% (34/36). Six (16.7%) eyes had intraocular pressure higher than 25 mm Hg. The visual acuity (logMAR) improved from 0.98±0.74 preoperatively to 0.52±0.31 postoperatively (P<0.001).

CONCLUSION

The success rate of this modified retinal repair surgery is comparable with traditional surgery. This technique can be considered for certain retinal detachment patients, since its apparent advantages included lower surgical complications, reduced surgery expenditure, shorter time for postoperative facedown position, and avoiding silicone oil removal surgery.

Inverted internal limiting membrane insertion combined with air tamponade in the treatment of macular hole retinal detachment in high myopia: study protocol for a randomized controlled clinical trial

Background

Macular hole retinal detachment (MHRD) occurs most commonly in high myopia and causes severe visual impairment and greatly reduces the quality of life. The aim of this study is to evaluate the efficacy and safety of inverted internal limiting membrane insertion combined with air tamponade in the treatment of MHRD in high myopia, and also to compare the treatment efficacy with that of the conventional “vitrectomy plus internal limiting membrane peeling plus silicone oil tamponade” method for high myopia-associated MHRD.

Methods/design

In this clinical trial, 38 patients with MHRD in high myopia will be randomly assigned to two groups (Group 1: standard 3-port 23-gauge pars plana vitrectomy plus internal limiting membrane peeling plus air-fluid exchange plus silicone oil infusion; Group 2: standard 3-port 23-gauge pars plana vitrectomy plus internal limiting membrane peeling plus inverted internal limiting membrane insertion plus air-fluid exchange). The primary outcome is macular hole closure rate in 3 months after the initial surgery. The secondary outcomes are best corrected visual acuity (BCVA), reattachment rate of retinal detachment, and postoperative complication rate.

Discussion

The study results may help to evaluate the efficacy and safety of inverted internal limiting membrane insertion combined with air tamponade in the treatment of MHRD in high myopia, and also compare the efficacy of the new treatment with the conventional “vitrectomy plus internal limiting membrane peeling plus silicone oil tamponade” method. This trial may provide a novel surgical treatment for MHRD in high myopia with more effectiveness and less pain.

Trial registration

ClinicalTrials.gov, NCT03383731. Registered on 19 December 2017. Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2833-y) contains supplementary material, which is available to authorized users.

Pars plana vitrectomy with partial tamponade of filtered air in Rhegmatogenous retinal detachment caused by superior retinal breaks

BACKGROUND

To investigate the anatomic and functional outcomes of pars plana vitrectomy (PPV) with partial tamponade of filtered air for rhegmatogenous retinal detachment (RRD) caused by superior retinal breaks.

METHODS

Retrospective, comparative, consecutive case series study. Patients with RRD caused by superior retinal breaks undergone PPV with partial tamponade (Group A) and whole tamponade (Group B) of filtered air were included. The main outcomes were primary and final success rates, best corrected visual acuity (BCVA), and rate of postoperative cataract surgery.

RESULTS

Forty-one patients (41 eyes) were included in Group A and 36 patients (36 eyes) were included in Group B. There were no significant differences in primary or final success rates between Groups A and B (P = 0.618 and P = 1.000, respectively). The patients in Group A experienced quicker postoperative vision improvement (from the Week 1 follow-up) than the patients in Group B (from the Month 3 follow-up). The postoperative cataract surgery rate of Group A (7/31) was lower than that of Group B (13/26) (P = 0.031).

CONCLUSIONS

PPV with partial tamponade of air is effective in achieving a high anatomic success rate, quicker postoperative vision improvement, and lower rate of postoperative cataract surgery in RRD caused by superior retinal breaks.

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.