2. Ghanbari MD 1390:10:29

3. Vitrectomy in diabetic retinopathy

6. Twenty five percent of diabetic patients have diabetic retinopathy, and 5% have severe (NPDR) or (PDR).

7. The cumulative incidence of proliferative diabetic retinopathy after 20 yr duration is about 14%.

8. Blindness is 25 times more common in diabetic patients than in those without diabetes.

9. laser photocoagulation is the mainstay of treatment for PDR to reduce visual loss and to avoid the needs for vitrectomy.

11. Even in eyes with severe complications, early (PRP) may improve subsequent surgical outcomes.

12. Machemer and coworkers first performed pars plana vitrectomy for the management of complications of diabetic retinopathy in 1970.

13. Indications for Diabetic Vitrectomy
Nonclearing vitreous hemorrhage.
Traction retinal detachment involving the macula.
Combined tractional-rhegmatogenous retinal detachment.
Progressive active fibrovascular proliferation.
Macular edema associated with posterior hyaloidal traction.
Dense premacular hemorrhage.
Dense vitreous hemorrhage in the presence of anterior segment neovascularization.

14. STANDARD SURGICAL TECHNIQUES
ANESTHESIA
local
general anesthesia.
The choice of anesthesia depends on the surgeon's and patient's preferences, the estimated duration of the procedure, and any systemic conditions that might place the patient at increased risk with general anesthesia.

15. REMOVAL OF VITREOUS HEMORRHAGE
If the vitreous hemorrhage is dense, preoperative ultrasonography is useful to delineate areas of retinal detachment and to ascertain whether a posterior vitreous detachment is present.

16. MEMBRANE DISSECTION
Techniques for removal of epiretinal fibrovascular membranes have evolved over the past 10 years. Three techniques, or combinations thereof, are commonly used, including :
(1) segmentation,
(2) delamination,
(3) “en bloc” dissection,
(4) combined.

17. SEGMENTATION
Segmentation is the earliest method used to release retinal traction caused by preretinal fibrovascular proliferation.

18. SEGMENTATION A. Core vitrectomy is performed.
B. Peripheral vitreous is removed, releasing all anteroposterior traction on the epiretinal membrane.
C. The epiretinal membrane is segmented by cutting bridging tissue between foci of fibrovascular adhesion.
D. Segmentation has been completed, and panretinal endophotocoagulation is applied.

19. DELAMINATION
Delamination begins similarly to segmentation with the removal of the partially detached posterior vitreous surface between the vitreous base and the edge of the fibrovascular adhesions. Using bimanual techniques, from anterior to posterior, the edge of the fibrovascular membrane is reflected using either a lighted pick, lighted forceps, the light pipe, or a tissue manipulator.

20. EN BLOC” VITRECTOMY AND MEMBRANE EXCISION
The en bloc technique uses the anteroposterior traction of the vitreous to elevate the edge of the fibrovascular membrane, thus serving as a “third hand.” Removal of the formed vitreous is delayed until the end of the membrane removal.

21. PRIMARY INDICATIONS FOR VITREORETINAL SURGERY
NONCLEARING VH
Generally is the least complex.
Prevalence has decreased with extensive use of PRP.
It remains a common indication for diabetic vitrectomy.

22. VH VH

24. Dense premacular hemorrhage
A subgroup of patients with intraocular hemorrhage secondary to proliferative diabetic retinopathy have dense premacular hemorrhage.
This is characterized by blood that is tightly confined between the macula and the posterior vitreous face of an incomplete posterior vitreous detachment.
The hyaloid is attached in the region surrounding the hemorrhage.

27. DENSE PREMACULAR HEMORRHAGE
Whereas most subhyaloid hemorrhages clear spontaneously, some eyes with dense premacular hemorrhage develop premacular fibrosis or traction macular detachment.

28. Timing of vitrectomy for nonclearing vitreous hemorrhage
Duration of hemorrhage,
Type of diabetes,
Severity of retinopathy
Status of the fellow eye.
Eighty-one percent of eyes had improved visual acuity on final examination.

29. Timing of Vitrectomy
The Diabetic Retinopathy Vitrectomy Study extensively evaluated the timing of vitrectomy for eyes with vitreous hemorrhage.
Specifically, it examined the outcome of early (before 6 months) yersus deferred (1 year) vitrectomy for severe vitreous hemorrhage, defined as central vitreous hemorrhage reducing visual acuity to 5/200 or less for at least 1 month.

30. In type 1 diabetic patients with vitreous hemorrhage, vitrectomy performed within 6 months gave more favorable visual and anatomic results than did deferral of surgery for 1 year or longer

31. The DRVS demonstrated that in eyes with severe vitreous hemorrhage (visual acuity 5/200 or less) , early vitrectomy (1 to 6 months after the onset of hemorrhage) resulted in final visual acuity of 20/40 or better in 25% of cases (at 2-year follow-up), compared with 15% of cases in the group with deferred surgery (1 year or until macular detachment occurred).

32. ln the type 2 and intermediate groups, however, there was little difference .between early vitrectomy and deferral of surgery regarding recovery of good vision (16% versus 18%).
The advantage for early vitrectomy remained after 4 years of follow-up.

33. Preoperative visual acuity of 5/200 or better. Absence of NVI OR NVG.
Preoperative factors associated with a favorable visual prognosis included the following
Preoperative visual acuity of 5/200 or better.
Absence of NVI OR NVG.
Minimal cataract.
PRP of at least one fourth of the fundus.

34. MACULAR TRACTION RETINAL DETACHMENT
Charles and Flinn studied the natural history of diabetic extramacular traction retinal detachment.
They found a progression to macular detachment in only 13.8% of eyes at 1-year follow-up.

36. Tractional retinal detachment

37. In patients with macular TRD, surgery should not be deferred for an extended period of time because retinal vascular changes may cause irreversible macular damage, reducing the potential for visual recovery.

38. This study defined traction retinal detachment as retinal elevation at least four disc areas in extent, at least part of which was within 30 degrees of the center of the macula.

39. Retinal elevation less than four disc areas if one or more vitreoretinal adhesions causing elevation of the retina were present within 30 degrees of the center and in the presence of active new vessels or fresh vitreous hemorrhage.

40. ln chronic retinal detachment involving the macula, the retina is usually atrophic and thin, and the fibrous membranes are often very tightly adherent. These factors limit anatomic success, and photoreceptor degeneration limits functional success.
Macular detachment greater than 6 months to 1 year usually precludes the return of useful vision, and surgery is not commonly performed in this situation.

41. A, Traction retinal detachment threatening the fovea
A, Traction retinal detachment threatening the fovea. Note the fibrotic membranes along the inferotemporal arcade and traction detachment just inferotemporal to the fovea.
The membranes extend to the fovea causing distortion. B, Postoperative appearanoe following vitrectomy, membranectomy,
and retinal reattachment.

42. Traction retinal detachment outside the macula

44. Intraoperative factors associated with a worse visual prognosis included:
Lensectomy.
Iatrogenic retinal breaks.
Use of intraocular gas tamponade.

45. COMBINED TRACTION-RHEGMATOGENOUS RETINAL DETACHMENT
Unlike purely tractional detachments, extramacular rhegmatogenous detachments frequently progress to involve the macula, leading to rapid and severe visual loss.

46. Thus, surgical repair is indicated in combined detachments, whether or not the macula is involved.
Often, the retinal breaks are located posterior to the equator, adjacent to areas of fibrovascular proliferation that are under severe vitreoretinal traction.

47. Therefore, this condition is difficult to treat by conventional scleral buckling methods, whereas vitrectomy (with or without scleral buckling) is effective in treating this condition.
Intraocular long-acting gas tamponade is required to treat these detachments.

48. Combined traction-rhegmatogenous detachments have a lower success rate than pure tractional detachments or nonclearing vitreous hemorrhage.

49. Preoperative factors associated with a favorable visual prognosis included visual acuity of 5/200 or better, absence of iris neovascularization, and absence of retinal detachment involving the macula. The only intraoperative factor found to be associated with a favorable visual prognosis was the absence of iatrogenic retinal breaks.

50. PROGRESSIVE ACTIVE FIBROVASCULAR PROLIFERATION
for eyes with active, progressive, fibrovascular proliferation despite maximal panretinal photocoagulation, vitrectomy should be considered.

51. However, vitrectomy does not take the place of panretinal photocoagulation and should be reserved only for eyes where laser cannot be applied or where laser has failed to stabilize the neovascular proliferation.

55. MACULAR EDEMA ASSOCIATED WITH POSTERIOR HYALOIDAL TRACTION
ETDRS showed that focal macular photocoagulation is beneficial in the treatment of clinically significant diabetic macular edema.
it has been observed that some patients with diabetic macular edema and a taut, thickened posterior hyaloid do not respond to macular photocoagulation.

56. It has been hypothesized that vitreous traction may cause or exacerbate macular edema in these patients.

57. Fundus photograph of an eye with vitreomacular traction syndrome.
B. Fluorescein angiography showing deep, diffuse dye leakage.

59. Optical coherence tomography scan showing clinically
invisible stage 1 posterior vitreous detachment with focal
vitreofoveolar attachment causing traction cystoid macular edema.

60. Optical coherence tomogram (OCT) demonstrating
posterior hyaloidal traction (PHT) (arrows). Tangential
traction exerted by the PHT is identified on OCT as a highly
reflective band over the retinal surface.

61. Spectral-domain optical coherence tomography
scan from an eye with diabetic macular edema demonstrating
stage 1 posterior vitreous detachment with adhesion zone
approximately 1500 m in diameter and without a definite
traction profile.

62. MEDIA OPACITY IN THE PRESENCE OF IRIS NEOVASCULARIZATION
In patients with potential for useful vision who present with dense vitreous hemorrhage and iris neovascularization or neovascular glaucoma, delaying vitrectomy to wait for possible clearance of the hemorrhage is not a viable option.

65. These eyes require prompt panretinal photocoagulation to treat the anterior segment neovascularization.
Vitrectomy allows clearance of media opacity so that panretinal endophotocoagulation can be applied.

66. COMPLICATIONS OF DIABETIC VITRECTOMY
Intraoperative Complications   Corneal edema   Miosis   Lens opacification   Intraocular hemorrhage   Iatragenic retinal breaks or detachment
 Postoperative Complications   Cataract   Recurrent vitreous hemorrhage   Glaucoma   Anterior hyaloidal fibrovascular proliferation   Retinal detachment   Intraocular fibrin syndrome   Endophthalmitis

67. Corneal Edema
The most common intraoperative complication during diabetic vitrectomy is corneal epithelial haze.
corneal epithelial defects heal slowly in diabetic patients, and diabetics are at particularly high risk of developing chronic, nonhealing corneal epithelial defects.
Thus, epithelial debridement should be avoided if possible.

68. Miosis
Some diabetic patients, particularly those with rubeosis irides, do not dilate well.
Miosis also may occur intraoperatively because of direct iris trauma or prolonged hypotony.
Topical NSAIDS agents have been shown to prolong intraoperative mydriasis

69. Lens Opacification Direct trauma from intraocular instruments,
Lengthy surgery,
Sustained elevated intraocular pressure, or
Increased infusion fluid volumes.

70. Feather-like opacities of the posterior capsule often occur with lengthy surgery or when the patient's blood glucose is significantly higher than that in the infusion fluid.

71. Intraocular Hemorrhage
If the bleeding is more profuse, making localization of the bleeding source difficult, the intraocular pressure can be raised to tamponade the bleeding and allow the source to be treated with diathermy.
Extensive preoperative panretinal photocoagulation helps to prevent intraocular hemorrhage by reducing the extent and caliber of neovascular vessels.

72. Iatrogenic Retinal Breaks
Iatrogenic retinal breaks continue to be a serious complication of vitreous surgery in diabetics.
In a series of 179 eyes of patients undergoing vitrectomy for complications of diabetic retinopathy, iatrogenic retinal breaks occurred in 20%.

73. `
At the end of the procedure, before closing the sclerotomies, a thorough examination of the retinal periphery should be performed with scleral depression and indirect ophthalmoscopic study to detect any retinal breaks that may have occurred.

74. If air-fluid exchange is planned, inspection of the retinal periphery should be performed beforehand because air or gas may close retinal breaks, making them difficult to detect

75. POSTOPERATIVE COMPLICATIONS
CATARACT
is the most common postoperative complication of diabetic vitrectomy.
Early cataract formation usually results from surgical trauma or prolonged lens contact with intraocular gas

76. POSTOPERATIVE COMPLICATIONS
Recurrent Vitreous Hemorrhage
have been reported in up to 50% of eyes after diabetic vitrectomy.
Residual hemorrhage from dissected fibrovascular tissue usually resolves without further intervention or complication, although it may take several months.

77. Persistent postoperative hemorrhage is undesirable, since it contains chemotactic and mitogenic factors and has been shown to stimulate fibrous ingrowth and epiretinal membrane formation.

78. POSTOPERATIVE COMPLICATIONS
Glaucoma
Acceptable pressure levels must be determined on an individual basis, although transient pressures less than 30 mmHg rarely require treatment.

79. Neovascular glaucoma once was a common complication after diabetic vitrectomy but now occurs less frequently because panretinal photocoagulation.
Aphakia,
RRD,
extensive retinal ischemia.

80. Anterior Hyaloidal Fibrovascular Proliferation
AHFP is a serious and potentially devastating complication of vitrectomy.
Patients who develop AHFP tend to be young with extensive NVE and severe retinal ischemia.

81. IOL capture and fibrovasular tissue posterior to the IOL ten months after cataract surgery.

82. This condition often becomes apparent with hemorrhage into the vitreous cavity or anterior hyaloid 3 to12 weeks after vitrectomy and is the result of fibrovascular proliferation from the peripheral retina extending toward the equator of the lens and on to the posterior lens capsule.

83. It is characterized by extraretinal fibrovascular proliferation of the anterior retina that extends along the anterior hyaloid to the posterior surface of the lens.
Contraction of this tissue can cause recurrent vitreous hemorrhages, retinal breaks and rhegmatogenous retinal detachments, or traction detachment of the peripheral retina or ciliary body leading to phthisis bulbi.

84. Treatment of AHFP is difficult, often requiring scleral buckling, lensectomy, resection of anterior vitreous and fibrovascular membranes, and extensive laser or retinocryopexy. Silicone oil has been used successfully for earlier or less severe cases.

85. Retinal Detachment
Retinal breaks or traction that were preexisting and not noticed or were inadequately treated.
Development of new breaks.

86. Traction detachments that do not include the macula can be observed and may not require further treatment.
Posterior breaks without traction can be treated with an intraocular gas bubble, proper positioning, and laser photocoagulation.
Detachments with peripheral breaks or posterior breaks with traction require repeat surgery, usually with scleral buckling and long-acting gas tamponade.

87. Intraocular Fibrin Syndrome
Fibrin formation frequently is seen in the early postoperative period after vitrectomy.
Severe fibrin formation is more common in eyes with rubeosis, after extensive neovascular proliferative tissue dissection, or when extensive endo PRP has been performed.

88. Tissue plasminogen activator (tPA), a fibrinolytic enzyme, is effective in dissolving fibrin membranes.

89. Endophthalmitis Endophthalmitis after pars plana vitrectomy is rare.
A study evaluating the 10-year incidence of postoperative endophthalmitis found an incidence of 0.046% after vitrectomy compared with an incidence of 0.093% for all surgeries.

90. The largest published series of patients with postvitrectomy endophthalmitis included 18 eyes and showed an incidence of 0.07%.
Endophthalmitis may be more common after vitrectomy in diabetics than in nondiabetics.

91. Endophthalmitis after vitrectomy can be poor visual outcome.

93. اما، اگر عزت نفس نداري، پس بدان که هيچ نداري.
جمله ای از گوته
اگر ثروتمند نيستي مهم نيست، بسياري از مردم ثروتمند نيستند
اگر سالم نيستي، هستند افرادي که با معلوليت و بيماري زندگي مي کنند،
اگر زيبا نيستي برخورد درست با زشتي هم وجود دارد،
اگر جوان نيستي، همه با چهره پيري مواجه مي شوند
اگر تحصيلات عالي نداري با کمي سواد هم مي توان زندگي کرد،
اگر مقام نداري، مشاغل مهم متعلق به معدودي انسان هاست،
اما، اگر عزت نفس نداري، پس بدان که هيچ نداري.

94. Thank You