The Management of Retinal Detachment: Techniques and Perspectives 2018View this Special Issue
Complications Associated with the Use of Expandable Gases in Vitrectomy
Intraocular gases have been used in vitreoretinal surgery for over 40 years. The aim of this study was to review the complications related to the use of expandable gases in vitrectomy and their management. A PubMed, Cochrane Library, and Embase search was conducted using the terms “intraocular gas” and “vitrectomy for retinal detachment.” Of the articles retrieved by this method, all publications in English and abstracts of non-English publications were reviewed. Intraocular pressure elevation was reported in up to 58.9% patients after vitrectomy with expandable gas administration for retinal detachment. Vitreoretinal surgery is known to induce cataract development. With that, cataract progression is associated with lens exposure to intraocular gas, the duration of such exposure, patient’s age, and the magnitude of vitreous removal. With intraocular gas, the posterior surface of the lens becomes a strongly refractive factor, resulting in high myopia and temporary vision impairment. Other complications related to the use of expandable gases include anterior chamber and subconjunctival gas displacement. Single reports on subretinal and cranial gas migration were published. In vitrectomy for uncomplicated retinal detachments, attempts to shift from expandable gases towards air are observed. Nevertheless, gas tamponade remains a reasonable choice for patients suffering from retinal detachment.
Intraocular gases are one of the most useful adjuncts in vitreoretinal surgery and have been used as a substitute for air for over 40 years . Due to their lower water solubility than nitrogen, pure sulfur hexafluoride (SF6), hexafluoroethane (C2F6), and perfluoropropane (C3F8) will expand when injected into the eye. Their surface tensions prevent fluid movement into retinal breaks, supporting physiological removal of fluid from the retinal space and allowing chorioretinal adhesions. A recent study revealed that intraocular gases have been applied regularly in the years of 1998–2013 and use of C2F6 has increased compared to C3F8 . With that, pars plana vitrectomy is becoming the procedure of choice for rhegmatogenous retinal detachment (RRD) .
The aim of this study was to review the complications related to application of expandible gases in vitrectomy and possible alternatives.
PubMed, the Cochrane Library, and Embase were the main resources used to search the medical literature search. An extensive search was performed to identify the use and complications of intraocular gases in retinal detachment surgery as reported up to May 31, 2018. The following keywords were used in various combinations: retinal detachment, vitrectomy, intraocular gas, sulfur hexafluoride, SF6, perfluoromethane, CF4, perfluoroethane, hexafluoroethane, C2F6, perfluoropropane, octafluoropropane, C3F8, and complications. The reference lists of identified publications were also considered potential sources of relevant articles. Studies were critically reviewed to create an overview and guidance for further search. Only articles having English-language abstracts were included. No attempts to discover unpublished data were made. In addition to the search, selected chapters from relevant textbooks were included if necessary.
The search revealed 1980 records, and after excluding duplicates and studies without English abstracts, 1369 records were screened. We identified 60 publications that evaluated the use of intraocular gases for retinal detachment surgery and complications related to their use. The earliest studies date the 1970s, but more than half of the publications were released after 2000. One review relevant to the topic was found in the Cochrane Database of Systematic Reviews . Early research focused on gas pharmacokinetics, while more recent papers tended to evaluate the possibility of replacing expandable gases with air. The largest database study reported the outcomes of RD surgery in 3,403 eyes , while patient safety incidents were analyzed in 38,789 vitreoretinal procedures .
4. Gases Used in Retinal Detachment Surgery
The ideal gas for vitreoretinal surgery should be nontoxic, inert, insoluble in the aqueous humor, and have a lower water solubility than nitrogen . SF6 and perfluorinated short-chain carbon compounds are used (C2F6 and C3F8), and when injected into the eye, they undergo three phases before resorption: expansion, equilibration, and dissolution [7, 8]. First, the intraocular gas volume rises as the nitrogen diffusion rate into the bubble is greater than the dissolution of the gas into the surrounding tissue fluid compartment. Second, the concentration of nitrogen in the bubble is equilibrated with the bloodstream, and a small amount of expandable gas diffuses out of the eye. Finally, when the partial pressure of all gases in the bubble equals that in the fluid compartment, the dissolution begins . The water solubility decreases as the carbon chain is elongated. For example, a 0.4 cc gas bubble in rabbit models disappears on average in 6, 16, and 28 days for CF4, C2F6, and C3F8, respectively . The expandable gases’ expansive properties may be diminished or eliminated when diluted with air, subsequently increasing the outward diffusion . The gas concentration and its half-life are linearly correlated .
Clinically, the longevity of a gas tamponade may differ from a theoretical model. The gas bubble duration is greater in 20-gauge vitrectomy than in microincision vitrectomy surgery [12, 13]. Such results are associated with insufficient tightness in any unsutured 23-gauge sclerotomy, causing early postoperative microleakage. The half-life of intraocular gases is longer in phakic eyes than in pseudophakic/aphakic eyes, presumably due to increased convection in the vitreous cavity of pseudophakic/aphakic eyes, which can accelerate the absorption rate [7, 14, 15]. With that, longer gas duration is correlated with an increased axial length, vitreous presence, lower aqueous turnover, and blood flow [8, 14, 16]. A survey of vitreoretinal surgeons reported that the clinical longevity of a gas bubble after a complete air-gas exchange is 13–24 days for SF6, 28–44 days for C2F6, and 59–79 days for C3F8 .
5. Complications Related to the Use of Intraocular Gases
5.1. Gas Migration
Anterior chamber (AC) migration of intravitreal gas is a potential complication, which might occur even in phakic eyes with no significant zonular dehiscence or phacodonesis [17, 18]. Intraoperative gas migration into the AC hampers visualization of the posterior segment, and careful insertion of the tamponade agent without overpressurizing the globe is recommended to prevent this complication. To remove the gas from the AC and prevent further gas prolapse, it might be necessary to insert an ophthalmic viscoelastic device (OVD). In some cases, the OVD might be left inside the eye at the conclusion of surgery if migration still occurs; however, such approach necessitates careful IOP control and postoperative administration of hypotensive agents. Long-term presence of gas bubbles in the AC results in corneal edema and bullous keratopathy . The gas is not toxic to the endothelium itself; however, contact between the gas and corneal endothelium results in decreased endothelial cell nutrition . With that, pars plana vitrectomy itself results in a mild decrease in endothelial cell count . Gas in the AC is usually managed by dilating the pupil and placing the patient face down, to allow the bubbles return to the vitreous compartment, so that the endothelium is bathed by aqueous .
Subconjunctival gas migration is another potential complication, particularly in microincision vitreous surgery. Gas displacement might occur intraoperatively due to trocar-associated leakage and postoperatively as a result of inadequate sclerotomy closure. In long-term, gas leakage can result in reduction of intraocular gas volume and retinal tamponade, thus influencing the retinal reattachment rate. However, in most of the cases of minor leakage no treatment is required.
Subretinal gas migration is possible particularly in eyes with optic nerve colobomas or large optic pit . Imperfection in tissue overlying cavitary optic disc, faulty interconnections between the vitreous cavity, subarachnoid, and subretinal spaces, and pressure variations of cerebrospinal fluid play a critical role in subretinal gas displacement. Case reports on cranial migration of intraocular gas in the early postoperative period were published [24, 25]. Subsequently, the patients developed nausea, vomiting, and mental status changes. No surgical intervention was deemed necessary, and short-interval clinical follow-up and serial computed tomography scans were recommended. The intracranial gas gradually resolved spontaneously and so did the mental status changes; however, the vision was lost due to altered tamponade properties.
5.2. Raised Intraocular Pressure (IOP)
IOP increase in eyes with intraocular tamponade is a common postoperative complication reported in up to 58.9% of eyes [26, 27]. Elevated IOP after vitrectomy may cause optic nerve damage, retinal ischemia, and subsequent visual loss. The mechanism can be open angle, closed angle, or both. In open-angle mechanism, IOP elevation is due to intraocular gas expansion. Closed-angle cases are less common but are usually a result of anterior displacement of the iris-lens diaphragm and iridocorneal apposition with or without pupillary block.
Studies reporting the incidence of IOP elevation after vitrectomy with gas tamponade are presented in Table 1. Expandable gases are supplied with different concentrations ranging from 20% to 100%, in single-use or multiple-use systems and in low-pressure or high-pressure containers with reducers. In practice, the final concentration used during vitrectomy is at the surgeon’s discretion . Interestingly, vitreoretinal surgeons commonly admit to having problems with incorrect gas concentration, and postsurgical IOP elevation is associated with high gas concentrations . Other risk factors include advanced patient age and concomitant circumferential scleral buckling [28, 32]. In older patients, increased risk of IOP elevation is related to decreased ocular elasticity and poorer aqueous outflow, while circumferential scleral buckles decrease outflow by elevating the episcleral venous pressure [32, 36]. The incidence of hypertony is also higher in 20-gauge vitrectomy compared to transconjunctival sutureless vitrectomy, as nonsutured sclerotomies allow a free passage of air/gas if IOP is elevated [37, 38].
Chen noted that, in the majority of cases, IOP elevation is transient with the highest mean values 2–4 hours postoperatively and lasts for up to 1 week after surgery . Elevated IOP potentially can be more dangerous in eyes with preexisting optic nerve damage, i.e., in glaucoma or atherosclerosis-related ischemia. Mittra et al. suggested prophylactic use of antihypertensive topical medication in patients with long-lasting gas tamponade, as in their studies they were necessary to prevent IOP elevation [34, 39]. It might be questioned whether prophylactic treatment should be recommended in all cases. We recommend vitreoretinal surgeons to benchmark their complication rate and adjust their surgical techniques and postoperative regimen.
When faced with high IOP due to an enlarging gas bubble, topical antihypertensive and systemic medications are recommended. Intravenous mannitol is known to work suboptimally in vitrectomized eyes, and several agents might be required to lower IOP. In some cases, it might be necessary to tap the gas in the outpatient clinic or operating room .
5.3. Cataract Development and Patient Positioning
Cataract is a common complication of vitreoretinal surgery, which develops due to inhibited diffusion of nutrients impeding proper lens metabolism . Exposure to intraocular gases additionally increases retrolental oxygen levels, resulting in development of lens opacities. The severity of cataract progression correlates with the longevity of intraocular tamponade . Cataracts that develop following expandable gas administration manifest as feathery formations, posterior capsule opacities, or vacuoles that are more intense in the superior part of the lens. Singh and associates noted that 18.8% of patients with intraocular gas tamponade develop cataract within three months after surgery . Jackson et al. found that 51.8% of phakic patients after vitrectomy with different gas tamponade agents have subsequent phacoemulsification cataract surgery in the following 6 months . Importantly, extended vitrectomy with surgical posterior vitreous detachment and anterior vitreous removal additionally increases the risk of cataract development . Thompson et al. reported a more pronounced advancement in nuclear sclerosis in older age groups . Postoperatively, the first symptom of nuclear sclerosis might be a myopic shift in refraction .
In order to decrease the contact between the gas bubble and the lens, patients might be instructed to avoid supine positioning . Prone positioning might be indicated to support hole closure, as most retinal breaks develop between the posterior vitreous base and the equator . With that, face-down positioning prevents forward movement of the lens-iris diaphragm caused by anterior pressure of the gas bubble, particularly in cases of floppy or atrophic iris [46–49]. Interestingly, in a study by Otsuka et al., prone position was maintained only on the day of surgery, followed by supine positioning for 7 days, and resulted in similar outcomes compared to strict prone positioning . Nevertheless, it might be concluded that in general, patients with intraocular expandible gas should avoid supine positioning. Cataract development is associated with the duration of lens exposure to gas, patient’s age, and the magnitude of vitreous removal.
5.4. Other Complications
The presence of intraocular gases results in light scattering on the interface between the gas bubble and adjacent intraocular fluid [10, 42]. Due to the high difference in refractive indexes between the gas and the lens, the posterior surface of the lens becomes a strongly refractive factor. Intraocular gases induce high myopia up to 50 D, which progressively diminishes as the size of the bubble decreases . Patients should be informed about the reasons for vision impairment after intraocular gas administration, and it should be taken into consideration when establishing the treatment plan in monocular individuals. Variations in atmospheric pressure affect the total volume of the gas bubble. Thus, safety of patients with intraocular gas is endangered by air travel, particularly in eyes without a scleral buckle [51, 52].
Another potential complication of vitreoretinal surgery is hypotony. Although the incidence of hypotony is significantly lower in eyes with air/gas tamponade than in cases with no tamponade , it was reported after 31% of vitrectomies with C3F8 applied . In most cases hypotony recovers without persistent damage; however, it does impose potential risks, i.e., increased reoperation rate .
In experimental studies, Doi and associates noted thinning or disappearance of the outer plexiform layer of rabbits’ superior retina after intravitreal administration of 0.4 ml·C3F8 . This finding was presumably associated with mechanical damage of the retina related to the contact with the expansive gases, rather than the toxicity of the vitreous substitute. In vivo studies did not confirm the influence of gas tamponade on retinal layer segmentation; however, reduction in the ganglion cell and outer retinal layers was found in eyes with long-term silicone oil tamponade .
6. Alternatives to Expandable Gases in Retinal Detachment Surgery
In addition to possible complications associated with long-acting gases, other disadvantages include their cost, the time, and workload required to acquire and store them and additional surgical time for dilution and administration. Several studies assessed the utility of air tamponade for eyes undergoing vitreoretinal surgery [57, 58]. A significant advantage of applying air compared to expandible gases is a shorter prone-positioning and recovery period. Tan and associates presented that patients with complete air tamponade had a similar vitrectomy success rate compared to 20% SF6, but only in RRDs with upper quadrants involved . Zhang et al. reported similar success rate RRDs with superior retinal breaks in eyes with partial and complete air tamponade . In other studies, air was used exclusively for tamponade in vitrectomy for RD, resulting in the similar reattachment rate in inferior breaks as well [57, 58]. Nevertheless, the majority of primary uncomplicated RRDs remain treated with expandible gas tamponade.
As air does not provide a long-term tamponade, it cannot be considered in eyes with recurrent RDs, in primary RDs that are associated with a varying intensity of proliferative vitreoretinopathy, or growth of fibrous tissue . Schwartz et al. in the Cochrane Database for Systematic Reviews revealed that only the use of perfluoropropane (C3F8) or silicone oil is a reasonable choice for most patients with RD associated with proliferative vitreoretinopathy . With that, long-lasting gas tamponade with C2F6 or C3F8 might be recommended for RRDs with inferior breaks or with giant retinal tears [61, 62].
The use of intraocular gases can result in postoperative intraocular pressure elevation, cataract formation, gas migration, and temporary vision impairment due to the a high difference in refractive indexes between the gas and the lens. In vitrectomy for uncomplicated retinal detachments, attempts to shift from expandable gases towards air are observed. Nevertheless, gas tamponade remains a reasonable choice for patients suffering from retinal detachment.
A. Methods for Literature Search
Literature searches of the PubMed, Embase, and Cochrane databases were conducted in May 2018; the search strategies are as follows. Specific limited update searches were conducted after May 2018.
A.1. PubMed Searches (Publication Date 1/10/11–5/31/2018)
((“retinal detachment”[MeSH]) OR (“vitrectomy”[MeSH])) AND ((“gas”[MeSH]) OR (“sulfur hexafluoride”[MeSH]) OR (“perfluoromethane”[MeSH]) OR (“perfluoroethane”[MeSH]) OR (“perfluoropropane”[MeSH]) OR (“octafluoropropane”[MeSH]) OR (“SF6”[Title/Abstract]) OR (“CF4”[Title/Abstract]) OR (“C2F6”[Title/Abstract]) OR (“C3F8”[Title/Abstract])). 803 references.
A.2. Cochrane Searches (Publication Date 1/10/11–5/31/2018)
MeSH descriptor Retinal Detachment explode all trees in Cochrane Database of Systematic Reviews. 23 references.
MeSH descriptor Vitrectomy explode all trees in Cochrane Database of Systematic Reviews. 15 references.
A.3. Embase Searches (Publication Date 1/10/11–5/31/2018)
((“retinal detachment”/de OR “retinal detachment”) OR (“vitrectomy”/de OR “vitrectomy”)) AND ((“gas”/de OR “gas”) OR (“sulfur hexafluoride”/de OR “sulfur hexafluoride”) OR (“perfluoromethane”/de OR “perfluoromethane”) OR (“perfluoroethane”/de OR “perfluoroethane”) OR OR (“perfluoropropane”/de OR “perfluoropropane”) OR (“octafluoropropane”/de OR “octafluoropropane”) OR (“SF6”/de OR “SF6”) OR (“CF4”/de OR “CF4”)OR (“C2F6”/de OR “C2F6”) OR (“C3F8”/de OR “C3F8”)) 1139 references.
Conflicts of Interest
The authors declare that they have no conflicts of interest.
E. W. Norton, “Intraocular gas in the management of selected retinal detachments,” Transactions-American Academy of Ophthalmology and Otolaryngology, vol. 77, no. 2, pp. OP85–OP98, 1973.View at: Google Scholar
B. Gupta, J. E. Neffendorf, and T. H. Williamson, “Trends and emerging patterns of practice in vitreoretinal surgery,” Acta Ophthalmologica, 2016.View at: Publisher Site | Google Scholar
S. G. Schwartz, H. W. Flynn Jr, W.-H. Lee, and X. Wang, “Tamponade in surgery for retinal detachment associated with proliferative vitreoretinopathy,” Cochrane Database of Systematic Reviews, vol. 14, no. 2, 2014.View at: Publisher Site | Google Scholar
T. L. Jackson, P. H. J. Donachie, J. M. Sparrow, and R. L. Johnston, “United Kingdom National Ophthalmology Database study of vitreoretinal surgery: report 2, macular hole,” Ophthalmology, vol. 120, no. 3, pp. 629–634, 2013.View at: Publisher Site | Google Scholar
S. C. Wong, S. P. Kelly, and P. M. Sullivan, “Patient safety in vitreoretinal surgery: quality improvements following a patient safety reporting system,” British Journal of Ophthalmology, vol. 97, no. 3, pp. 302–307, 2013.View at: Publisher Site | Google Scholar
E. J. Sigler, J. C. Randolph, S. Charles, and J. I. Calzada, “Intravitreal fluorinated gas preference and occurrence of rare ischemic postoperative complications after pars plana vitrectomy: a survey of the american society of retina specialists,” Journal of Ophthalmology, vol. 2012, Article ID 230596, 5 pages, 2012.View at: Publisher Site | Google Scholar
J. T. Thompson, “Kinetics of intraocular gases. Disappearance of air, sulfur hexafluoride, and perfluoropropane after pars plana vitrectomy,” Archives of Ophthalmology, vol. 107, no. 5, pp. 687–691, 1989.View at: Publisher Site | Google Scholar
I. Y. Wong and D. Wong, “Special adjuncts to treatment,” Retina, Elsevier, Amsterdam, Netherlands, 2013.View at: Google Scholar
H. Lincoff, J. Mardirossian, A. Lincoff, P. Liggett, T. Iwamoto, and F. Jakobiec, “Intravitreal longevity of three perfluorocarbon gases,” Archives of Ophthalmology, vol. 98, no. 9, pp. 1610-1611, 1980.View at: Publisher Site | Google Scholar
M. G. Krzystolik and D. J. D’Amico, “Complications of intraocular tamponade: silicone oil versus intraocular gas,” International Ophthalmology Clinics, vol. 40, no. 1, pp. 187–200, 2000.View at: Publisher Site | Google Scholar
J. T. Thompson, “The absorption of mixtures of air and perfluoropropane after pars plana vitrectomy,” Archives of Ophthalmology, vol. 110, no. 11, p. 1594, 1992.View at: Publisher Site | Google Scholar
S. Singh, R. Byanju, S. Pradhan, and G. Lamichhane, “Retrospective study on outcome of macular hole surgery,” Nepalese Journal of Ophthalmology, vol. 8, no. 2, p. 139, 2017.View at: Publisher Site | Google Scholar
S. Kusuhara, S. Ooto, D. Kimura et al., “Intraocular gas dynamics after 20-gauge and 23-gauge vitrectomy with sulfur hexafluoride gas tamponade,” Retina, vol. 31, no. 2, pp. 250–256, 2011.View at: Publisher Site | Google Scholar
A. Kontos, J. Tee, A. Stuart, Z. Shalchi, and T. H. Williamson, “Duration of intraocular gases following vitreoretinal surgery,” Graefe’s Archive for Clinical and Experimental Ophthalmology, vol. 255, no. 2, pp. 231–236, 2017.View at: Publisher Site | Google Scholar
J. J. Crittenden, “Expansion of long-acting gas bubbles for intraocular use,” Archives of Ophthalmology, vol. 103, no. 6, p. 831, 1985.View at: Publisher Site | Google Scholar
M. S. Lee, M. Pasha, and M. Weitzman, “The effect of aqueous humor suppressants on intravitreal gas bubble duration in rabbits,” American Journal of Ophthalmology, vol. 125, no. 5, pp. 701-702, 1998.View at: Publisher Site | Google Scholar
C. S. H. Tan, K. Wee, M.-D. Zaw, and T. H. Lim, “Anterior chamber gas bubble following pneumatic retinopexy in a young, phakic patient,” Clinical and Experimental Ophthalmology, vol. 39, no. 3, pp. 276-277, 2011.View at: Publisher Site | Google Scholar
R. M. Taher and R. Haimovici, “Anterior chamber gas entrapment after phakic pneumatic retinopexy,” Retina, vol. 21, no. 6, pp. 681-682, 2001.View at: Publisher Site | Google Scholar
R. W. Kim and C. Baumal, “Anterior segment complications related to vitreous substitutes,” Ophthalmology Clinics of North America, vol. 17, no. 4, pp. 569–576, 2004.View at: Publisher Site | Google Scholar
D. L. Van Horn, H. F. Edelhauser, T. M. Aaberg, and H. J. Pederson, “In vivo effects of air and sulfur hexafluoride gas on rabbit corneal endothelium,” Investigative ophthalmology, vol. 11, no. 12, pp. 1028–1036, 1972.View at: Google Scholar
E. Cinar, M. O. Zengin, and C. Kucukerdonmez, “Evaluation of corneal endothelial cell damage after vitreoretinal surgery: comparison of different endotamponades,” Eye, vol. 29, no. 5, pp. 670–674, 2015.View at: Publisher Site | Google Scholar
J. T. Thompson, “Intraocular gases and techniques for fluid-air exchange,” in Vitreoretinal Surgical Techniques, G. A. Peyman, S. A. Meffert, F. Chou, and M. D. Conway, Eds., pp. 157–172, CRC Press, Boca Raton, FL, USA, 2000.View at: Google Scholar
T. M. Johnson and M. W. Johnson, “Pathogenic implications of subretinal gas migration through pits and atypical colobomas of the optic nerve,” Archives of Ophthalmology, vol. 122, no. 12, pp. 1793–1800, 2004.View at: Publisher Site | Google Scholar
L. T. Lim, E. Y. Ah-Kee, B. P. House, and J. D. Walker, “The management of gas-filled eyes in the emergency department,” Case Reports in Emergency Medicine, vol. 2014, Article ID 347868, 3 pages, 2014.View at: Publisher Site | Google Scholar
H. K. Bhatt, “Pneumocephalus following macular hole repair,” Archives of Ophthalmology, vol. 125, no. 11, pp. 1583-1584, 2007.View at: Publisher Site | Google Scholar
S. Chang, H. A. Lincoff, D. Jackson Coleman, W. Fuchs, and M. E. Farber, “Perfluorocarbon gases in vitreous surgery,” Ophthalmology, vol. 92, no. 5, pp. 651–656, 1985.View at: Publisher Site | Google Scholar
D. P. Han, H. Lewis, F. H. Lambrou Jr, W. F. Mieler, and A. Hartz, “Mechanisms of intraocular pressure elevation after pars plana vitrectomy,” Ophthalmology, vol. 96, no. 9, pp. 1357–1362, 1989.View at: Publisher Site | Google Scholar
G. W. Abrams, D. E. Swanson, W. I. Sabates, and A. I. Goldman, “The results of sulfur hexafluoride gas in vitreous surgery,” American Journal of Ophthalmology, vol. 94, no. 2, pp. 165–171, 1982.View at: Publisher Site | Google Scholar
“Vitrectomy with silicone oil or perfluoropropane gas in eyes with severe proliferative vitreoretinopathy: results of a randomized clinical trial. Silicone study report 2,” Archives of Ophthalmology, vol. 110, no. 6, pp. 780–792, 1992.View at: Google Scholar
“Vitrectomy with silicone oil or sulfur hexafluoride gas in eyes with severe proliferative vitreoretinopathy: results of a randomized clinical trial,” Archives of Ophthalmology, vol. 110, no. 6, pp. 770–779, 1992.View at: Google Scholar
R. Wong, B. Gupta, T. H. Williamson, and D. A. H. Laidlaw, “Day 1 postoperative intraocular pressure spike in vitreoretinal surgery (VDOP1),” Acta Ophthalmologica, vol. 89, no. 4, pp. 365–368, 2009.View at: Publisher Site | Google Scholar
P. P. Chen and J. T. Thompson, “Risk factors for elevated intraocular pressure after the use of intraocular gases in vitreoretinal surgery,” Ophthalmic Surgery and Lasers, vol. 28, no. 1, pp. 37–42, 1997.View at: Google Scholar
C. J. Chen, “Glaucoma after macular hole surgery,” Ophthalmology, vol. 105, no. 1, pp. 94–100, 1998.View at: Publisher Site | Google Scholar
R. A. Mittra, J. S. Pollack, S. Dev, D. P. Han, W. F. Mieler, and T. B. Connor, “The use of topical aqueous suppressants in the prevention of postoperative intraocular pressure elevation following pars plana vitrectomy with long-acting gas tamponade,” Transactions of the American Ophthalmological Society, vol. 96, pp. 143–151, 1998.View at: Google Scholar
P. Kanclerz and A. Grzybowski, “Case series of inappropriate concentration of intraocular sulfur hexafluoride,” Case Reports in Ophthalmology, vol. 9, no. 2, pp. 405–410, 2018.View at: Publisher Site | Google Scholar
R. Grytz, M. A. Fazio, V. Libertiaux et al., “Age- and race-related differences in human scleral material properties,” Investigative Ophthalmology and Visual Science, vol. 55, no. 12, pp. 8163–8172, 2014.View at: Publisher Site | Google Scholar
S. J. Ahn, S. J. Woo, J. Ahn, and K. H. Park, “Comparison of postoperative intraocular pressure changes between 23-gauge transconjunctival sutureless vitrectomy and conventional 20-gauge vitrectomy,” Eye, vol. 26, no. 6, pp. 796–802, 2012.View at: Publisher Site | Google Scholar
R. Duval, J. M. Hui, and K. A. Rezaei, “Rate of sclerotomy suturing in 23-gauge primary vitrectomy,” Retina, vol. 34, no. 4, pp. 679–683, 2014.View at: Publisher Site | Google Scholar
R. A. Mittra, J. S. Pollack, S. Dev et al., “The use of topical aqueous suppressants in the prevention of postoperative intraocular pressure elevation after pars plana vitrectomy with long-acting gas tamponade,” Ophthalmology, vol. 107, no. 3, pp. 588–592, 2000.View at: Publisher Site | Google Scholar
J. E. Bourgeois and R. Machemer, “Results of sulfur hexafluoride gas in vitreous surgery,” American Journal of Ophthalmology, vol. 96, no. 3, pp. 405–407, 1983.View at: Publisher Site | Google Scholar
A. Modi, A. Giridhar, and M. Gopalakrishnan, “Sulfurhexafluoride (SF6) versus perfluoropropane (C3F8) gas as tamponade in macular hole surgery,” Retina, vol. 37, no. 2, pp. 283–290, 2017.View at: Publisher Site | Google Scholar
K. M. P. Yee, S. Tan, S. Y. Lesnik Oberstein et al., “Incidence of cataract surgery after vitrectomy for vitreous opacities,” Ophthalmology Retina, vol. 1, no. 2, pp. 154–157, 2017.View at: Publisher Site | Google Scholar
J. T. Thompson, W. E. Smiddy, B. M. Glaser, R. N. Sjaarda, and H. W. Flynn Jr, “Intraocular tamponade duration and success of macular hole surgery,” Retina, vol. 16, no. 5, pp. 373–382, 1996.View at: Publisher Site | Google Scholar
S. S. Kim, W. E. Smiddy, W. J. Feuer, and W. Shi, “Outcomes of sulfur hexafluoride (SF6) versus perfluoropropane (C3F8) gas tamponade for macular hole surgery,” Retina, vol. 28, no. 10, pp. 1408–1415, 2008.View at: Publisher Site | Google Scholar
K. Otsuka, H. Imai, A. Miki, and M. Nakamura, “Impact of postoperative positioning on the outcome of pars plana vitrectomy with gas tamponade for primary rhegmatogenous retinal detachment: comparison between supine and prone positioning,” Acta Ophthalmologica, vol. 96, no. 2, pp. e189–e194, 2018.View at: Publisher Site | Google Scholar
L. Gopal, A. Nagpal, S. Kabra, and J. Roy, “Anterior chamber collapse following vitreoretinal surgery with gas tamponade in aphakic eyes: incidence and risk factors,” Retina, vol. 26, no. 9, pp. 1014–1020, 2006.View at: Publisher Site | Google Scholar
R. Rahman and P. H. Rosen, “Pupillary capture after combined management of cataract and vitreoretinal pathology,” Journal of Cataract and Refractive Surgery, vol. 28, no. 9, pp. 1607–1612, 2002.View at: Publisher Site | Google Scholar
K. Shinoda, “Posterior synechia of the Iris after combined pars plana vitrectomy, phacoemulsification, and intraocular lens implantation,” Japanese Journal of Ophthalmology, vol. 45, no. 3, pp. 276–280, 2001.View at: Publisher Site | Google Scholar
N. Lois and D. Wong, Complications of Vitreo-Retinal Surgery, Lippincott Williams and Wilkins, Philadelphia, PA, USA, 2013.
R. Gizicki and M. Sebag, “Optical effects of intraocular gas bubbles and prognostic value of early post-operative vision in vitreo-retinal surgery as measured with an iphone snellen chart,” Investigative Ophthalmology and Visual Science, vol. 52, p. 6151, 2011.View at: Google Scholar
J. P. Dieckert, P. S. O’Connor, D. E. Schacklett et al., “Air travel and intraocular gas,” Ophthalmology, vol. 93, no. 5, pp. 642–645, 1986.View at: Publisher Site | Google Scholar
J. Noble, N. Kanchanaranya, R. G. Devenyi, and W.-C. Lam, “Evaluating the safety of air travel for patients with scleral buckles and small volumes of intraocular gas,” British Journal of Ophthalmology, vol. 98, no. 9, pp. 1226–1229, 2014.View at: Publisher Site | Google Scholar
G. Bamonte, M. Mura, and H. Stevie Tan, “Hypotony after 25-gauge vitrectomy,” American Journal of Ophthalmology, vol. 151, no. 1, pp. 156–160, 2011.View at: Publisher Site | Google Scholar
C. C. Barr, M. Y. Lai, J. S. Lean et al., “Postoperative intraocular pressure abnormalities in the silicone study. Silicone study report 4,” Ophthalmology, vol. 100, no. 11, pp. 1629–1635, 1993.View at: Publisher Site | Google Scholar
M. Doi, M. Ning, R. Semba, Y. Uji, and M. F. Refojo, “Histopathologic abnormalities in rabbit retina after intravitreous injection of expansive gases and air,” Retina, vol. 20, no. 5, pp. 506–513, 2000.View at: Publisher Site | Google Scholar
S. H. Lee, J. W. Han, S. H. Byeon et al., “Retinal layer segmentation after silicone oil or gas tamponade for macula-on retinal detachment using optical coherence tomography,” Retina, vol. 38, no. 2, pp. 310–319, 2018.View at: Publisher Site | Google Scholar
K. Y. Pak, S. J. Lee, H. J. Kwon, S. W. Park, I. S. Byon, and J. E. Lee, “Exclusive use of air as gas tamponade in rhegmatogenous retinal detachment,” Journal of Ophthalmology, vol. 2017, Article ID 1341948, 5 pages, 2017.View at: Publisher Site | Google Scholar
C. Zhou, Q. Qiu, and Z. Zheng, “Air versus gas tamponade in rhegmatogenous retinal detachment with inferior breaks after 23-gauge pars plana vitrectomy: a prospective, randomized comparative interventional study,” Retina, vol. 35, no. 5, pp. 886–891, 2015.View at: Publisher Site | Google Scholar
H. S. Tan, S. Y. L. Oberstein, M. Mura, and H. M. Bijl, “Air versus gas tamponade in retinal detachment surgery,” British Journal of Ophthalmology, vol. 97, no. 1, pp. 80–82, 2013.View at: Publisher Site | Google Scholar
Z. Zhang, M. Peng, Y. Wei, X. Jiang, and S. Zhang, “Pars plana vitrectomy with partial tamponade of filtered air in Rhegmatogenous retinal detachment caused by superior retinal breaks,” BMC Ophthalmology, vol. 17, no. 1, p. 64, 2017.View at: Publisher Site | Google Scholar
J. E. Neffendorf, B. Gupta, and T. H. Williamson, “The role of intraocular gas tamponade in rhegmatogenous retinal detachment: a synthesis of the literature,” Retina, vol. 38, pp. S65–S72, 2017.View at: Publisher Site | Google Scholar
P. J. Banerjee, A. Chandra, P. Petrou, and D. G. Charteris, “Silicone oil versus gas tamponade for giant retinal tear-associated fovea-sparing retinal detachment: a comparison of outcome,” Eye, vol. 31, no. 9, pp. 1302–1307, 2017.View at: Publisher Site | Google Scholar