Ординатура / Офтальмология / Английские материалы / Retinal and Vitreoretinal Diseases and Surgery_Boyd, Cortez, Sabates_2010

Figure 6: Retinal Reattachment With Perfluorocarbon Liquid in Case of Giant Tear - Stage 2. As more perfluorocarbon liquid (P - blue arrow) is injected into the vitreous cavity via cannula (N), the subretinal fluid (S) is forced out (red arrows) from behind the detached retina into the vitreous cavity and out of the eye via the cannula. The retina (R) is reattached (green arrows). Infusion cannula (I). Endoilluminator (E). (Art from Jaypee Highlights Medical Publishers.)

tears and PVR. They are also of great value in surgery of dislocated crystalline lenses or intraocular lenses, drainage of suprachoroidal hemorrhages, and retinal detachment associated with vitreous hemorrhage, especially when the retinal tear is hidden by blood.

Perfluorocarbon Liquids of Choice

Among the PFC liquids that have been described for treating complicated retinal detachments and giant retinal tears, most surgeons prefer to use perfluoro-n-octane because of its physical properties.13 Perfluoro-n-octane has a molecular weight of 438 daltons, a specific gravity of 1.76, a surface tension of 14 dynes per centimeter at 25 degrees Celsius,

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a refractive index of 1.27, a vapor pressure of 50 mm Hg at 37 degrees Celsius, and a viscosity of 0.10 centistokes at 25 degrees Celsius.Perfluoro-n-octanehasgreatervisibility during surgery, lower viscosity, and higher vapor pressure when compared to perfluorodecalin and perfluorophenantrine, making it the ideal PFC for vitreoretinal surgery.

The greater visibility is important because it enables the surgeon to differentiate the perfluoro-n-octane from balanced salt solution (BSS). This allows the vitreoretinal surgeon to monitor the PFC level during intraoperative injection and obtain a more complete removal, which is required due to the long-term toxicity of these liquids. In addition, it enables the surgeon to remove the BSS from the edge of peripheral tears during fluid-air exchange, thereby preventing the ingress of BSS into the subretinal space. This differentiation is not visible with other PFCs because their refractive index is closer to water.

The lower viscosity of perfluoro-n-octane is important because PFC liquids with higher viscosity are difficult to inject and remove from the eye. Sometimes it is advantageous to inject the PFC liquid rapidly, which is easier with a liquid of lower viscosity. But most importantly, it is critical to remove all the PFC liquid from the eye. This substance is not used as a long-term intraocular tamponade, although it has been shown in a few reports to be safe and effective as a short-term tamponade.14-18 Experimental, electrophysiological, and histological studies in human and rabbit eyes have demonstrated that PFCs can be toxic to the retina, particularly when they remain in the eye in large quantity or for a long period of time.19-23 The cornea can also become edematous in areas of contact

with the PFC liquid. Therefore, a complete replacement of the vitreous by PFC liquid for long-term use is not advisable.

Finally, the higher vapor pressure of per- fluoro-n-octane allows a small residual amount of the liquid to evaporate during the fluidair exchange and in the early postoperative period, which is another reason why it is currently the preferred PFC.

Indications for Perfluorocarbon Liquids

Although PFC liquids may be used in the repairofallretinaldetachmentsassociatedwith giant tears, they are particularly indicated in the following scenarios: giant tears in which the posterior margin of the tear has inverted and must be unrolled during vitrectomy surgery, giant tears complicated by moderate or severe degrees of PVR, and traumatic giant tears associated with vitreous or retinal incarceration into the wound or with severe subretinal hemorrhage. The main advantage of PFC liquids as an intraoperative “tool” is that they limit the need to manipulate the retina mechanically. Therefore, the risk of potential complications such as hemorrhage, retinaltears,andre-proliferationissignificantly reduced.

Using PFC liquids in eyes that have giant retinal tears with PVR also allows the surgeon to identify residual epiretinal or subretinal membranes in the equatorial region and to perform the operation with the patient in a supine position, thus avoiding the need for rotational tables or beds and intraoperative prone positioning as in the pre-PFC era.24

Surgical Technique for Uncomplicated Giant Retinal Tears

Removing the Basal Vitreous Gel

Before Injecting Perfluoro-n-octane

To completely remove the basal vitreous gel, the lens most often needs to be removed even if it is clear. The surgeon performs a pars plana lensectomy, taking care to remove completely the posterior capsule (if an intraocular lens is not going to be placed). Then, using the vitreous cutter, he or she performs a total posterior vitrectomy. With scleral depression, the basal vitreous gel is debulked for 360 degrees (Figure 7). Then the surgeon injects perfluoro-n-octane using a panoramic

Figure 7: Technique for Removing Basal Vitreous. The central vitreous gel and lens are removed before injecting perfluorocarbon liquid. After the lens is removed, a total posterior vitrectomy is performed. With the aid of scleral depression (D), the basal vitreous gel (B) is debulked as shown for 360 degrees using a vitreous cutter (V) through the pars plana. Note the giant tear

(T). Infusion cannula (I). The light pipe (L) is placed over the cornea to provide illumination. (Art from Jaypee Highlights Medical Publishers.)

wide-field viewing system. The Chang cannula is used to inject the PFC liquid very slowly over the optic nerve head (Figure 8). The volume of PFC liquid in the vitreous cavity is increased in a controlled, slow way to unroll the inverted posterior retinal flap, allowing the retina to return to its normal anatomic position25 (Figure 9a-c). The PFC

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liquid is not brought above the giant retinal tear unless the surgeon is certain there is no residual traction. Otherwise, the PFC liquid can migrate under the retina. Even if a small bubble remains under the retina, it can be toxic and can lead to a scotoma postoperatively.20

Removing the Anterior Flap and

Liquid-Air-Gas Exchange

After the PFC liquid completely reattaches the retina, many surgeons advocate excision of the anterior flap of the giant retinal tear with the vitreous cutter (Figure 10). The anterior flap is removed to prevent it from migrating anteriorly and exerting traction on the ciliary processes, which could lead to hypotony despite retinal reattachment. Removing the anterior flap also prevents the ischemic retina from leading to iris neovascularization. Once the retina is reattached and the anterior flap has been removed, endophotocoagulation is

used through the PFC liquid to treat the giant retinal tear and any other retinal breaks that may be present. It also is suggested that the laser treatment be extended at least one clock hour beyond the margins of the giant tear, because the giant tears often extend circumferentially.

Following endophotocoagulation, a PFC liquid-air exchange is performed, and care is taken to remove all fluid before removing the PFC liquid (Figure 11). It is very important to dry the edge of the giant retinal tear to prevent slippage of the posterior flap. After the fluid is removed above the PFC liquid

Figure 11: Technique of Perfluorocarbon Liquid / AirGas Exchange. First, all intraocular fluid is removed above the level of the PFC liquid and the giant retinal tear, and exchanged with air (A - black arrow) entering through an infusion cannula (C). With the giant tear dry, the PFC liquid (F) is then removed (red arrow) posterior to the giant tear via an aspiration cannula

(B) as air continues to fill 100% of the cavity. If the fluid anterior to the giant tear is not removed prior to removing the perfluorocarbon liquid, slippage occurs. Endoilluminator (E). (Art from Jaypee Highlights Medical Publishers.)

and the edge of the giant retinal tear is dried, the liquid is removed while air is entering the eye through the infusion cannula. The surgeon must take care to remove all the small bubbles of residual PFC liquid that remain on the epiretinal surface. With perfluoro-n-octane, it is very easy to visualize these small residual bubbles. Finally, an air-gas exchange is performed with a nonexpansile concentration of perfluoropropane gas. This can be performed by injecting the

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gas through the infusion cannula and venting air through an open sclerotomy. Another technique involves closing all sclerotomies, injecting the gas via a 30-gauge needle, and venting with a 27-gauge needle through the pars plana. The latter technique allows for greater control of intraocular pressure by avoiding the sudden loss of gas that one may encounter when removing the infusion cannula. The use of a panoramic wide-field viewing system greatly facilitates performing most of the intraocular steps of the surgery. At the end of the procedure, the conjunctiva is closed, and the patient is positioned appropriately to allow the optimal gas tamponade of the giant retinal tear.

The Scleral Buckle Controversy in

Giant Tears Without PVR

An important controversy in the treatment of giant retinal tears without PVR is whether or not to place an encircling scleral buckle. Many surgeons only place scleral buckles in eyes with PVR or in eyes at significant risk for developing PVR (Figure 12). These include eyes with marked retinal pigment epithelial cell dispersion into the vitreous, preoperative choroidal detachments, or star folds in the retina.

If a scleral buckle is not placed, the surgeon must be sure to have released all potential traction, shave the vitreous base 360 degrees (Figure 8), and try to ensure that the patient will not need re-operation or that the retina will not re-detach. The main causes of re-detachment following giant retinal tear surgery include the development of PVR and folds along the giant retinal tear that allow

Figure 12: Scleral Buckle in Cases of Giant Tear with PVR or Potential PVR. This example shows the proper placement of a wide, broad and moderately elevated scleral buckle (S) in the case of a giant tear. The 7mm silicone exoplant is placed to cover the entire vitreous base (B), including the posterior border. Note the giant tear (T). The scleral buckle is placed to support the non-torn retina. (Art from Jaypee Highlights Medical Publishers.)

vitreous fluid to leak through and re-detach the retina.5,6 These folds may be caused by persistent traction from basal vitreous gel. If the crystalline lens is not removed and the basal vitreous gel is not debulked, a circumferential scleral buckle should be employed.26,27

Surgical Technique for Giant Retinal Tear with PVR

Patients with giant retinal tears with PVR or a high likelihood of developing PVR are frequently managed with a scleral buckle accompanying the vitrectomy. A scleral buckle is typically not used to close a standard giant

retinal tear because the traction has already been released (the vitreous is not attached to the posterior flap), and no connection exists between the tear and the anterior retina. The rationale to use a scleral buckle is to support the non-torn retina. A 7 mm silicone exoplant buckle is generally broad enough to cover the entire vitreous base, including the posterior border (Figure 12).9 If the patient does not have anterior PVR and the lens is clear, the lens can remain in the eye.

If the patient has anterior PVR or the lens is not clear, however, a pars plana lensectomy with complete removal of the posterior capsule should be performed. If the lens is not removed, the vitreous base cannot be completely debulked (Figure 8). In these cases, a scleral buckle will counteract some of the anterior traction.

Removing Epiretinal Membranes

In patients with giant retinal tears associated with PVR, it is important to remove as many posterior epiretinal membranes as possible prior to injecting PFC liquid.28 Bimanual dissection using an illuminated pick and a mini-diamond tip forceps often is effective in removing epiretinal membranes while minimizing iatrogenic retinal breaks. Once most or all of the epiretinal membranes have been removed, the perfluoro-n-octane is injected over the optic nerve head to open retinal folds, to unfold the posterior flap of the giant retinal tear, and to allow better visualization of areas with residual preretinal or subretinal membranes. The posterior flap of the giant retinal tear is stabilized as more PFC liquid is injected. The edge of the tear is examined as the PFC liquid bubble approaches it. Epiretinal or subretinal membranes present

Figure 13: Technique for Removal of Epiretinal Membranes on the Inner Surface of the Posterior Edge of a Giant Tear. As perfluorocarbon liquid (F) is injected, the edge of the posterior flap (P) of the giant tear is monitored. Resistance to unfolding by the PFC liquid may give a clue to the presence of epiretinal membranes on the inner surface of the posterior edge of the tear. Epiretinal membranes (M) on the inner surface may give the edge a rolled appearance and can cause a circumferential shortening along the edge. These membranes should be dissected with a vitreoretinal pick as shown, or if this is not possible, excised. Panoramic viewing lens

(L) and infusion cannula (I). (Art from Jaypee Highlights Medical Publishers.)

on the inner surface of the posterior edge of the giant retinal tear are identified by a rolled appearance of this edge. These membranes can cause a circumferential shortening along the edge of the retinal tear and should be opened by dissection or excision using the vitreous cutter (Figure 13). Additional PFC liquid is injected until the level lies just posterior to the margin of the tear. The large volume of PFC liquid stabilizes the retina and allows close trimming of the peripheral or basal vitreous gel. With traditional viewing systems, the retinal edge may disappear from the field

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of view of the operating microscope as the retina is flattened. The use of a panoramic viewing system offers the advantage of obtaining a wide field allowing observation of the entire retina during PFC injection and removal, facilitating endophotocoagulation. Small radial or circumferential folds that have flattened along the edge of the tear can be gently smoothed using a spatula.

Some cases of more chronic retinal detachment associated with a giant tear will have extensive subretinal proliferation. In these cases, it will be necessary for the surgeon to dissect the subretinal membranes prior to the injection of PFC liquid. On occasion, it may be necessary to enlarge the giant tear in order to gain better access to the subretinal space.

The remainder of the operation is the same as the procedure for giant retinal tear without PVR. The giant retinal tear is treated with endophotocoagulation while the PFC liquid is still in the eye. Then a PFC liquid-air exchange is performed. The air is subsequently exchanged for gas.

Silicone Oil Controversy

In addition to the scleral buckle controversy, the other major unresolved issue in treatment for giant retinal tears concerns the choice of a long acting gas like perfluoro-propane or silicone oil as the intraocular tamponade.29-31 Indications for silicone oil in patients with giant retinal tears are the same as in patients with PVR: patients who need to travel by air, children who cannot be positioned prone postoperatively, patients whose back or neck conditions preclude prone positioning after surgery, and monocular patients who require better vision immediately.31

Surgical Results

The two largest, prospective, multicenter case series utilizing PFC liquids in the management of giant retinal tears were performed by Scott et al. and Kertes et al. These studies revealed recurrent detachment rates of 49% and 30%, and final attachment rates of 91% and 79%, respectively. Preoperative characteristics portending a greater risk of recurrent detachment in both studies included larger size of retinal tear and preoperative PVR.13,15 As expected, patients with uncomplicated giant retinal tears demonstrated better visual results than patients with preoperative PVR.15 As in other types of retinal detachment, the main complication or cause of failure in the management of giant retinal tears is the development of PVR following surgery and the need for re-operation.5,6

Traditionally,scleralbuckleshavebeenused in the management of giant retinal tears.7,9 In 1969, Norton and colleagues became the first not to use a scleral buckle in the treatment of giant retinal tears. Instead, they used an intraocular air bubble.32 Kreissig and colleagues successfully reattached the retina in five eyes of patients with giant retinal tears using a retrohyaloidal injection of gas without vitrectomy or scleral buckling.33 The use of pneumatic retinopexy without scleral buckling or vitrectomy was also reported by Irvine and Lahey.34 Several authors have reported using vitreous surgery without concomitant scleral buckling in the treatment of giant retinal tears. Leaver and colleagues used vitrectomy and silicone oil injection without scleral buckle in some of the eyes reported in their series.35 Hoffman and Sorr reported successful reattachment in 6 eyes with giant retinal tears using vitrectomy and perfluoropropane gas

without scleral buckling. 36 Chang and associates repaired 6 eyes with giant retinal tears without scleral buckling using vitrectomy with PFC liquid and intraocular gas.37 Ambresin and colleagues reported successful reattachment in 16 of 18 patients with giant retinal tears using 360-degree laser photocoagulation in conjunction with vitrectomy and silicone oil tamponade, but without scleral buckling.38 Kreiger and Lewis described a series of 11 patients with uncomplicated giant retinal tears treated with vitrectomy, radical dissection of the vitreous base, injection of perfluoro-n- octane, endophotocoagulation, PFC liquid-air exchange, but no scleral buckle. Initial and final retinal attachment rates in this series were 91% and 100%, respectively.39

In summary, the ideal surgical technique for uncomplicated giant retinal tears would be one that would achieve intraoperative and long-term retinal reattachment without complications or a need for re-operation. There is almost universal agreement that the surgical technique should include pars plana vitrectomy, PFC liquids, and photocoagulation while viewing the fundus with panoramic systems. This allows for excellent anatomic re-apposition of the flap, the avoidance of slippage, and limited dispersion of the retinal pigment epithelial cells. Ultimately, this leads to a decreased risk of proliferation, recurrent retinal detachment, and re-operation. Controversy continues about whether giant retinal tears without severe PVR require scleral buckling and lensectomy. Scleral buckling providesadvantagesincludingsupportingnontorn retina at the vitreous base and reducing the risk of further tearing. The disadvantages include the possibility of promoting slippage or retinal folding which could possibly lead to re-detachment and cause more surgical

trauma. In cases in which a scleral buckle is not used, lens removal allows for the debulking of the basal vitreous gel and reduces vitreoretinal traction, decreasing the rate of recurrent retinal detachment and re-operation.

References

1.Ang A, Poulson AV, Goodburn SF, Richards AJ, Scott JD, Snead MP. Retinal detachment and prophylaxis in type1Sticklersyndrome.Ophthalmology2008;115(1):164- 8.

2.Parma ES, Körkkö J, Hagler WS, Ala-Kokko L. Radial perivascular retinal degeneration: a key to the clinical diagnosis of an ocular variant of Stickler syndrome with minimal or no systemic manifestations. Am J Ophthalmol 2002;134(5):728-34.

3.Stickler GB, Hughes W, Houchin P. Clinical features of hereditary progressive arthro-ophthalmopathy (Stickler syndrome): a survey. Genet Med 2001;3(3):192-6.

4.Schepens CL. Retinal detachment and allied diseases.

Philadelphia: WB Saunders, 1983: 520–8.

5.Glaser BM. Treatment of giant retinal tears combined with proliferative vitreoretinopathy. Ophthalmology 1986;93(9):1193-7.

6.Freeman HM, Castillejos ME. Current management of giant retinal breaks: results with vitrectomy and total air fluid exchange in 95 cases. Trans Am

Ophthalmol Soc 1981; 79:89-102.

7.MichelsRG,RiceTA,BlankenshipG.Surgicaltechniques for selected giant retinal tears. Retina 1983;3(3):139-53.

8.Vidaurri-Leal J, de Bustros S, Michels RG. Surgical treatment of giant retinal tears with inverted posterior retinal flaps. Am J Ophthalmol 1984;98(4):463-6.

9.Holland PM, Smith TR. Broad scleral buckle in the management of retinal detachments with giant tears. Am J Ophthalmol 1977; 83 (4):518-25.

10.Chang S. Low viscosity liquid fluorochemicals in vitreous surgery. Am J Ophthalmol 1987;103(1):38-43.

11.Comaratta MR, Chang S. Perfluorocarbon liquids in the management of complicated retinal detachments.

Curr Opin Ophthalmol 1991;2(3):291-8.

Management of Giant Retinal Tears

411

12.Shapiro MJ, Resnick KI, Kim SH, Weinberg A. Management of the dislocated crystalline lens with a perfluorocarbon liquid. Am J Ophthalmol 1991;112(4):401-5.

13.Scott IU, Murray TG, Flynn HW Jr, Feuer WJ, Schiffman JC; Perfluoron Study Group. Outcomes and complications associated with giant retinal tear management using perfluoro-n-octane. Ophthalmology 2002;109(10):1828-33.

14.Blinder KJ, Peyman GA, Desai UR, Nelson NC Jr, Alturki W, Paris CL. Vitreon, a short-term vitreoretinal tamponade. Br J Ophthalmol 1992;76(9):525-8.

15.Kertes PJ, Wafapoor H, Peyman GA, Calixto N Jr, Thompson H. The management of giant retinal tears using perfluoroperhydrophenanthrene. A multicenter case series. Vitreon Collaborative Study Group. Ophthalmology 1997;104(7):1159-65.

16.Millsap CM, Peyman GA, Mehta NJ, Greve MD, Lee KJ, Ma PE, Dunlap WA. Perfluoroperhydrophenanthrene (Vitreon) in the management of giant retinal tears: results of a collaborative study. Ophthalmic Surg 1993;24(11):759-63.

17.Rofail M, Lee LR. Perfluoro-n-octane as a postoperative vitreoretinal tamponade in the management of giant retinal tears. Retina 2005;25(7):897-901.

18.Sirimaharaj M, Balachandran C, Chan WC, HunyorAP, Chang AA, Gregory-Roberts J, Hunyor AB, Playfair TJ. Vitrectomy with short term postoperative tamponade using perfluorocarbon liquid for giant retinal tears. Br J Ophthalmol 2005;89(9):1176-9.

19.de Queiroz JM, Jr., Blanks JC, Ozler SA, et al. Subretinal perfluorocarbon liquids. An experimental study. Retina 1992;12(3 Suppl):S33-9.

20.Elsing SH, Fekrat S, Green WR, Chang S, Wajer SD, Haller JA. Clinicopathologic findings in eyes with retained perfluoro-n-octane liquid. Ophthalmology 2001;108(1):45-8.

21.Garcia-Valenzuela E, Ito Y, Abrams GW. Risk factors for retention of subretinal perfluorocarbon liquid in vitreoretinal surgery. Retina 2004;24(5):746-52.

22.Lee GA, Finnegan SJ, Bourke RD. Subretinal perfluorodecalin toxicity. Aust N Z J Ophthalmol 1998;26(1):57-60.

23.Lesnoni G, Rossi T, Gelso A. Subfoveal liquid perfluorocarbon. Retina 2004;24:172-6.

24.Machemer R, Allen AW. Retinal tears 180 degrees and greater: management with vitrectomy and intravitreal gas. Arch Ophthalmol 1976;94:1340-1346.

25.Ie D, Glaser BM, Sjaarda RN, Thompson JT, Steinberg LE, Gordon LW. The use of perfluoro-octane in the management of giant retinal tears without proliferative vitreoretinopathy. Retina 1994;14(4):323-8.

26.Goezinne F, LA Heij EC, Berendschot TT, Gast ST, Liem AT, Lundqvist IL, Hendrikse F. Low redetachment rate due to encircling scleral buckle in giant retinal tears treated with vitrectomy and silicone oil. Retina 2008;28(3):485-92.

27.Verstraeten T, Williams GA, Chang S, Cox MS Jr, Trese MT, Moussa M, Friberg TR. Lens-sparing vitrectomy with perfluorocarbon liquid for the primary treatment of giant retinal tears. Ophthalmology 1995;102(1):17-20.

28.Glaser BM, Carter JB, Kuppermann BD, Michels RG. Perfluoro-octane in the treatment of giant retinal tears with proliferative vitreoretinopathy. Ophthalmology 1991;98(11):1613-21.

29.Batman C, Cekiç O. Vitrectomy with silicone oil or long-acting gas in eyes with giant retinal tears: longterm follow-up of a randomized clinical trial. Retina 1999;19(3):188-92.

30.Mathis A, Pagot V, Gazagne C, Malecaze F. Giant retinal tears: surgical techniques and results using perfluorodecalin and silicone oil tamponade. Retina 1992;12(3 Suppl):S7-10.

31.Scott IU, Flynn HW Jr, Azen SP, Lai MY, Schwartz S, Trese MT. Silicone oil in the repair of pediatric complex retinal detachments: a prospective, observational, multicenter study. Ophthalmology 1999;106(7):1399-407; discussion 1407-8.

32.Norton EW, Aaberg T, Fung W, Curtin VT. Giant retinal tears. I. Clinical management with intravitreal air. Am J Ophthalmol 1969;68(6):1011-21.

33.Kreissig I, Lincoff H, Stanowsky A. The treatment of giant tear detachments using retrohyaloidal perfluorocarbon gases without drainage or vitrectomy. Graefes Arch Clin Exp Ophthalmol 1987;225(2):94-8.

34.Irvine AR, Lahey JM. Pneumatic retinopexy for giant retinal tears. Ophthalmology 1994; 101 (3):524-8.

35.Leaver PK, Cooling RJ, Feretis EB, Lean JS, McLeod D. Vitrectomy and fluid/silicone-oil exchange for giant retinal tears: results at six months. Br J Ophthalmol 1984;68(6):432-8.

36.Hoffman ME, Sorr EM. Management of giant retinal tears without scleral buckling. Retina 1986 Win- ter;6(4):197-204.

37.Chang S, Lincoff H, Zimmerman NJ, Fuchs W. Giant retinal tears: surgical techniques and results using perfluorocarbon liquids.ArchOphthalmol1989;107(5):761-6.

38.Ambresin A, Wolfensberger TJ, Bovey EH. Management of giant retinal tears with vitrectomy, internal tamponade, and peripheral 360 degrees retinal photocoagulation. Retina 2003; 23 (5):622-8.

39.Kreiger AE, Lewis H. Management of giant retinal tears without scleral buckling. Use of radical dissection of the vitreous base and perfluoro-octane and intraocular tamponade. Ophthalmology 1992;99(4):491-7.

40.Lewis H., Giant Retinal Tears. World Atlas Series of Ophthalmic Surgery of Highlights, Boyd, BF., Vol. IV, 1999;(1):6-14.