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Pars Plana Vitrectomy Results in Proliferative Vitreoretinopathies

Objective: This study was carried out in order to evaluate the clinical features, surgical treatment results and complications encountered in patients who underwent pars plana vitrectomy due to PVR in our clinic. Methods: Forty-eight eyes of 47 patients who underwent pars plana vitrectomy for PVR were included in the study. Pars plana vitrectomy was applied to both eyes of one of these cases due to PVR. 29 (61.7%) of the cases were male and 18 (38.2%) were female. Routine ophthalmologic examination was performed to all patients. All operations were performed by the same surgeon. Results: Forty-eight eyes of 47 patients with various levels of PVR underwent pars plana vitrectomy. 29 eyes (60.41%) underwent once pars plana vitrectomy, 18 eyes (37.5%) underwent 2 times pars plana vitrectomy and 1 eye (2.08%) underwent 3 times pars plana vitrectomy. In the postoperative period, the patients were followed up between 2 months and 16 months (mean 6.6 months). At the end of the follow-up period, our anatomic success rate was 81.25% and total retinal attachment was achieved in 39 eyes. Retinal detachment was observed in 4 eyes (8.33%) anterior of scleral buckling, while posterior pole was attached. In 5 eyes (10.41%) retinal attachment could not be achieved and 3 of these eyes (6.25%) developed phthisis. Conclusions: Vitreretinal surgery can provide anatomical and functional success in eyes with rhegmatogenous retinal detachment and PVR. This success rate has increased especially in recent years with the use of gas and silicone oil as intraocular tamponade, intraoperative use of perfluorocarbon fluids, introduction of wide angle vision systems and advances in surgical techniques.


INTRODUCTION
MATERIAL AND METHODS PVR is characterized by cell proliferation in the vitreous and membrane formation on both surfaces of the retina. It occurs after prolonged retinal detachments and after detachment surgery. Contraction of these fibroproliferative membranes leads to a series of clinical changes ranging from decreased retinal and vitreous mobility to the formation of radial and circular folds (1).
Contraction of these membranes resulting from PVR causes to retinal traction. Retinal traction also leads to re-opening of previously successfully attached tears or the formation of new tears. Thus, recurrent retinal detachment, macular pucker and macular distortion may occur (2).
The presence of clinical features of PVR was known many years ago and was called massive periretinal proliferation and massive vitreous retraction before taking its current name (3)(4)(5)(6)(7)(8). In the last 20 years, significant progress has been made in understanding and treating the pathogenesis of PVR (9). Today, successful results are obtained in the treatment of PVR with pars plana vitrectomy surgery.
In this study, we evaluated the clinical features, surgical treatment results and complications of patients who underwent pars plana vitrectomy for PVR in our clinic.
Forty-eight eyes of 47 patients who underwent pars plana vitrectomy for proliferative vitreoretinopathy between March 1998 and April 2001 in SSK Istanbul Educational Hospital Eye Clinic were included in this retrospective study. Twenty-nine (61.7%) of the cases were male and 18 (38.2%) were female.
The ages ranged from 15 to 73 years (mean 50.1 years). The most frequent age group was 41-60 years. The patients were followed for a mean of 6.6 months between 2 months and 16 months.
The cases we included in the study were routinely: visual acuity examination, intraocular pressure measurement (with applanation tonometer), biomicroscopic anterior segment examination, biomicroscopic and indirect ophthalmoscopic fundus examinations and ultrasonography were performed in cases where the posterior segment could not be viewed Thirty two patients (68%) underwent pars plana vitrectomy under general anesthesia and 15 patients (32%) under local anesthesia. All operations were performed by the same surgeon.

RESULTS
Preoperative visual acuity of the patients included in our study ranged from light sensation to 0.1 ( Figure 1). Preoperative visual acuity of 44 eyes was light sensation.   Preoperative PVR levels of the eyes included in our study ranged from C1 to D3 according to the 1983 Retinal Society PVR Classification System. Stage DI PVR was the most common preoperative PVR level with 41.66%.
In the postoperative period, the patients were followed up between 2 months and 16 months (mean 6.6 months). A completely attached retina with clear illumination at the last follow-up was defined as anatomical success. The increase in preoperative visual acuity was accepted as functional success. At the end of the follow-up period, our anatomic success rate was 81.25% and total retinal attachment was achieved in 39 eyes. Retinal detachment was observed in 4 eyes (8.33%) anterior of scleral buckling, while posterior pole was attached. In 5 eyes (10.41%) retinal attachment could not be achieved and 3 of these eyes (6.25%) developed phthisis.
Silicon oil was used in 37 eyes (77.08%) and C3F8 was used in 10 eyes (20.83%) as intraocular tamponade. Because of massive suprachoroidal hemorrhage developed in one eye (2.08%) during the operation, the operation was terminated without intraocular tamponade. In 20 eyes (54.05%) we achieved silicone oil, and in 1 eye (2.70%) retinal attachment posterior of scleral buckling was achieved. Recurrent retinal detachment and PVR developed in 16 eyes (43.24%). One eye (2.70%) with silicone oil was treated with retinal detachment and retinal detachment developed after silicone removal. In 6 eyes (60%) we used C3F8 and in 3 eyes (30%) retinal attachment posterior of scleral buckling was achieved. Recurrent retinal detachment and PVR developed in 1 (10%) of the eyes given C3F8.
Visual acuity increased in 36 eyes (75%), visual acuity remained unchanged in 5 eyes (10.41%) and decreased in 7 eyes (14.58%). A total of 37 eyes (77.03%) had visual acuity of finger counting and over, and 30 (62.91%) of them had visual acuity counting from 1 meter and above. Postoperative visual acuity levels of the eyes included in our study are shown in Figure 2. Complications related to pars plana vitrectomy are shown in Table 2.

DISCUSSION
In our study, the anatomic success rate obtained at the end of the follow-up period was 81.25%, and total retinal attachment was achieved in 39 eyes. Retinal detachment was observed in 4 eyes (8.33%) anterior of scleral buckling, while posterior pole was attached. In 5 eyes (10.41%) retinal attachment could not be achieved and 3 of these eyes (6.25%) developed phthisis. Visual acuity improved in 36 eyes (75%), visual acuity remained unchanged in 5 eyes (10.41%) and decreased in 7 eyes (14.58%). A total of 37 eyes (77.03%) had finger counts and visual acuities, and 30 of them (62.91%) had visual acuities of 1 meter and above. Although there are differences between the success rates of the studies, success rates in the treatment of PVR have generally increased in parallel with the developments in surgical techniques. Even if some eyes require more than one surgical intervention due to reproliferation and recurrent retinal detachment, retinal detachment can be achieved successfully in most eyes with retinal detachment resulting from PVR (9).
Lewis and colleagues achieved significant degrees of anatomical and functional success following vitrectomy in eyes with retinal detachment resulting from PVR. They achieved 90% of total retinal attachment and 94% of retinal attachment posterior of scleral buckling. They achieved visual acuity of at least 5/200 in 85% of eyes with total retinal attachment. They did not achieve same success for eyes with recurrence PVR who previously underwent vitrectomy for PVR. In these eyes, 73% of the total retinal attachmnet and 86% of retinal attachment posterior of scleral buckling were achieved. They achieved 67% of visual acuity 5/200 and above in these eyes with total retinal attachment (10).
The most important reason of vitreoretinal surgery failure in eyes with PVR is the presence of anterior PVR in the preoperative period, the development of anterior PVR in the postoperative period, or the continuation of pre-existing anterior PVR. Diffuse anterior PVR is also the most important cause of chronic hypotonia (14,15,16). Therefore, the elimination of anterior PVR is of great importance. In eyes with PVR, scleral indentation is required in order to effectively clean the vitreous base, peripheral vitreous and anterior proliferative tissue. For this, it may be necessary to remove the crystalline and intraocular lens (17). We removed the crystalline or intraocular lens from 27 pseudophakic or phakic eyes (56.25%) to clean the vitreous base, peripheral vitreus and anterior proliferative tissue.
In complicated retinal detachment surgery, the buffer effect of gases used as intraocular tamponade is more than silicone and no second operation is required to remove the gases (18,19). Unlike gases, silicone is a stabilizer that can keep the eye at the same intraocular pressure. However, in order to maintain this effect, the retina must be free from all traction during the operation (19). The silicone has optical clarity, hemostatic effects and minimal refractive effects, allowing visual rehabilitation to be rapid. This allows easy selection of fundus details and easy application of intraoperative and postoperative laser. In addition, due to the mechanical effect of silicone can slow the spread of detachment, confine the detachment (20).
In our study, we used silicone oil in 37 eyes (77.08%) and C3F8 in 10 eyes (20.83%) as intraocular tamponade. We could not give intraocular tamponade because of massive suprachoroidal hemorrhage developed in one eye (2.08%). We achieved retinal attachment in 20 eyes (54.05%) used silicone oil, and in 1 eye (2.70%) with silicone oil retinal attachment posterior of scleral buckling was achieved. Recurrent retinal detachment and PVR developed in 16 eyes (43.24%). One eye (2.70%) with silicone oil was treated with retinal detachment and retinal detachment developed after silicone removal. Total retinal attachment was achieved in 6 eyes (60%) with C3F8 In 6 eyes (60%) and retinal attachment posterior to scleral buckling was achieved in 3 eyes (30%) with C3F8. Recurrent retinal detachment and PVR developed in 1 (10%) of the eyes given C3F8. We found a higher rate of both anatomical and functional success in eyes with C3F8 as intraocular tamponade. However, we think that using silicone oil in more eyes compared to C3F8 and preferring silicone oil in cases with high PVR stage have an effect on these results.

CONCLUSION
Anatomical and functional success can be achieved with vitreoretinal surgery in eyes with rhegmatogenous retinal detachment and PVR. This success rate has increased especially in recent years with the use of gas and silicone oil as intraocular tamponade, intraoperative use of perfluorocarbon fluids, introduction of wide angle vision systems and advances in surgical techniques.
Despite these advances in PVR surgery, success rates are not 100%. The most important reason for this is the continuation of the PVR process, which leads to recurrent retinal detachment and reduced functional success. Anterior and posterior membranes should be completely removed to stop the PVR process.
Although silicone oil and gases used as intraocular tamponade can achieve successful results, they do not have ideal tamponade properties because both have various disadvantages. However, silicone oil should be preferred in eyes more than one operated and prone to hypotonia because it has stabilizing and also has prevents phytisis and hypotonia as well as intravitreal tamponade.
Functional and anatomical success will be achieved when the ideal tamponade can be used in PVR surgery and pharmacological agents are used to prevent recurrent epiretinal proliferation, which is the most important complication of PVR surgery.