Visual Outcome after Early & Late Pars Plana Vitrectomy in Patients with Advanced Diabetic Eye Disease

Aim: Advanced diabetic eye disease, as a complication of proliferative diabetic retinopathy (PDR), is the potential and most serious cause of blindness among the patients with diabetes mellitus (DM). Functional results of vitrectomy for diabetic retinopathy were analyzed in to two groups with early and late vitrectomy, to improve our estimation of timing and risk of early and late vitreous surgery. It was a Quasi-experimental study; the primary objective of the study was to compare the visual outcome in patient with advanced diabetic eye disease after early and late pars-plana vitrectomy.
Methods: Total of 64eyes of 61 patients were included. Patients were divided in two groups. Those with history of deterioration of vision less than 6 month were included in Group A (early vitrectomy) and those with more than 6 month were included in group B (late vitrectomy). Final post operative visual acuity after pars plana vitrectomy were analyzed using SPSS 13.0 at the end of 6 month follow up .
Results: Visual acuity of 6/18 or better “(near) normal vision” was achieved by 27% eyes in group A (early vitrectomy) patients and 6.45 % eyes in group B (late vitrectomy) patients. Visual acuity of 6/24 to 6/50 “Moderately impaired vision” was achieved by 42.42% eyes of group A patients as compared to 32.25% eyes in group B patients. While visual acuity of 6/60 to 3/60 “severely impaired vision” was achieved by 58% eyes of group B patients as compared to 27% eyes in group A patients.
Conclusion. The visual prognosis after early vitrectomy is better than late vitrectomy in patients with advanced diabetic eye disease.
Key Words. Diabetes Mellitus, Pars Plana Vitrectomy, Diabetic Retinopathy, Vitreous Hemorrhage.

INTRODUCTION

Diabetes mellitus (DM) is a major health problem throughout the world. In Pakistan data are lacking, but the prevalence ranges from 8.6% to 13.9%2. It causes an array of long term systemic complications, which have considerable impact on  both the patient and society because it typically affects individuals in their most productive years of life2.Ophthalmic complications of diabetes include corneal abnormalities, glaucoma, iris neo-vascularization, cataract and neuropathies. However, the most common and potentially most blinding of these is diabetic retinopathy3


1.Assistant Prof, Helper’s Eye Hospital ,Bolan University of Medical and Health Sciences Quetta.
2. Assistant Prof, Khuzdar Medical College , Khuzdar, Balochistan .
3. Shaban Khan , Associate Prof, Helper’s Eye Hospital, Bolan University of Medical and Health Sciences Quetta.
5.Prof Dr Abdul Qayum , Chairman department of ophthalmology, Bolan University of Medical and Health Sciences Quetta.


Correspondence: Iftikhar ul Haq Tareen, Assistant Prof, Helper’s Eye
Hospital ,Bolan University of Medical and Health Sciences Quetta.
Mob 03333441186
whatsapp, 03217877701 E.Mail>iftikhartareen@yahoo.com


Received: June-2019 Accepted: Sep-2019


The visual prognosis after early vitrectomy is better than late vitrectomy in patients with advanced diabetic eye disease.


Photocoagulation and other treatment modalities are available for the treatment of proliferative diabetic retinopathy (PDR).The Diabetic Retinopathy Study (DRS) demonstrated that scatter photocoagulation with argon laser was effective in reducing visual loss from the complications of PDR4. However, several patients continued to suffer the consequences of PDR, either because vitreous hemorrhage and /or severe proliferation of neo-vascularization and fibrous tissue developed before any intervention could be offered. In others, photocoagulation failed to prevent progression to these stages leading to advanced diabetic eye disese5, which is characterized by; 1. Persistent intra-vitreal hemorrhage, 2. Tractional Retinal Detachment (TRD), 3. Epiretinal membrane formatiom6. In 1971, Machmer first reported successful vision restoration to patients with pars plana vitrectomy (PPV)7. It is a closed intraocular microsurgery which is to ensure that all ocular tissue and structure are in the correct anatomic location and proper configuration at the end of procedure.

The surgical objective for diabetic retinopathy includes:
1. Removal of vitreous opacities (i.e. hemorrhage).
2. Release of vitroretinal (antero-posterior) traction.
3. Pre-retinal fibrovascular membrane (tangential) traction.
4. Endolaser Photocoagulation8.

As the procedure became more technically refined, it was offered to increasing number of patients. There are both anatomic and physiologic goals of vitrectomy for PDR. The anatomic goals are to remove vitreous opacities and to remove fibro vascular traction so that detached retina can become reattached. The physiologic goal of fibrovascular membrane removal is to control proliferation. Successful vitreous surgery hats the process of further fibrovascular proliferation9. The opposing argument is that surgery posed too, great risk in these severally affected eyes10. Despite success in many eyes, operated patients had higher rate of complications and significant percentage lost all light perception. Critics of pars plana vitrectomy contented that risks of surgery are so high that an extended period of observation in eyes with these severely affected eyes should be allowed before surgery is considered10. The aim of this study was to determine whether early vitrectomy is more effective in persevering useful vision in eyes with severe active proliferative disease as compared to the conventional strategy of surgical intervention only after severe visual loss had occurred as a result of complications of PDR. It is also aimed to evaluate the natural course and effect of surgical intervention on these severely affected eyes.

METHODOLOGY

This prospective study was carried out at Eye Unit–I Helper’s Eye Hospital, Bolan Medical College, Quetta. The duration of the study was nine months (from November 2017 to July 2018), and total of 61 patients were included in this study. Patients were divided into two groups on non-probability bases, Group A and group B.
Group A: This group includes patient with advanced diabetic eye disease with history of marked deterioration of vision less than 6 months.
Group B: Patients with advanced diabetic eye disease with history of marked deterioration of vision more than 6 months were included in this group. The primary objective of this study was to compare the visual outcome in patients with advanced diabetic eye disease after early and late pars plana vitrectomy. Any betterment (at least one line in snellen type) or decrease in visual acuity of the patient, after surgery (vitrectomy). The principal outcome variable was the final best corrected visual acuity of the patient after six months’ follow up. The following classification of visual acuity (according to Visual standards reported by International Council of Ophthalmology at the 29th international congress of ophthalmology Sydney Australia April 2002)11 was used.

Visual acuity of 6/7.5 or batter
(Range of normal vision )

Visual acuity of 6/9 to 6/18
(mild visual impairment) (Near) Normal vision

Visual acuity of 6/24 to 6/50
(Moderate visual impairment )

Visual acuity of 6/60 to 3/60
(Sever visual impairment) Low Vision

Visual acuity of 2/60
( Profound visual impairment )

Visual Acuity of 1/60 ( Near blind)
No perception of light (NPL) (Near) Blindness

Following cases were included in the study. Age at least 20 years or more. Diabetes Mellitus diagnosed by physician (both type I and type II). Outlook good for survival and return for follow up for at least 6 months. 
 Following cases were excluded from the study. Previous vitrectomy. Intraocular pressure greater than 29mmHg. Severe iris neovascularization orneovascular glaucoma. Insufficient clarity of the cornea or lens which can affect the visual acuity. Data was collected regarding the demographic characteristics of the patient i.e. age, sex, and address. The regime followed was; Preoperative evaluation. Surgical procedures. Follow up visits. The surgical objectives for diabetic retinopathy include removal of vitrous opacities (hemorrhage) and release of vitroretinal (antero- posterior) and pre-retinal fibrovascular membrane (tangential) traction. En bloc dissection can often remove all membranes that are causing traction. Some times segmentation or trimming of the broad sheets of paramacular fibrous tissue (pre-retinal fibrovascular proliferation tightly adherent to the dense, fibrotic posterior vitreous surface) often allows the retina to relax enough so that retinal reattachment is possible. Internal drainage of sub retinal fluid can be performed through a retinal tear, inadvertent retinotomy, or intentional relaxing or drainage retinotomy. Intraocular tamponad with gas or silicone oil is then employed where ever needed. If hemorrhage occurred intra operatively it can be controlled by intraocular diathermy, increasing intraocular pressure or possibly by fluid-air exchange. Argon Laser endo-photocoagulation was used where ever needed. Patients were admitted and were examined on first and second post operative day. On 3rd postoperative day patients were discharged and prescribed post operative medications of steroid-antibiotic combination with cycloplegic as per need, oral antibiotics and analgesic were given for 5 days. For follow up visits patients were examined fortnightly for tow months and then after one month interval for 6 months. Visual acuity was noted on every follow up visit and at 6th month postoperatively. All data were analyzed using the SPSS 20.0 statistical software (SPSS Inc. Chicago, IL, USA). Chi-square test (df=1) and unpaired t test (df=3) were applied where ever needed.

RESULTS

One patient in group A and two patients in group B lost follow up so they were excluded from the study. Total of 64 eyes of 61 patients were analyzed. Male to female ratio was 1.5:1. The average age of the patients was 49.34 years with a range of 28 to 75years. The ratio of patients with type I DM (IDDM) to type II DM (NIDDM) was 1:2. 18(29.59%) patients were with type I DM and 43(70.49%) patients were diagnosed by physician as type II DM. In group A preoperative best corrected visual acuity in the eyes to be operated were 3/60 in 3(9.09%) eyes, in 5(15-15%) eyes was 2/60, in 15(45.45%)eyes was 1/60and in 10(30.30) eyes was perception of light (PL+). While the visual acuity recorded in the fellow eye rang from 6/6 to 1/60 with median value of 6/36. Preoperative visual acuity in the eyes to be operated in group B patients were 2/60 in 9(29.03%) eyes, 1/60 in 13(41.93%) and Perception of light (PL+) in 9(29.03%) eyes while the visual acuity of fellow eyes had a median value of 6/36 with range of 6/6 to perception of light (PL+). After 6 months follow up the final best corrected visual acuity recorded in group A patients, 9(27.27%) eyes were placed in category “(Near) Normal Vision” (6/18 or batter) according to standard laid down in the outcome measures ( ICO, Visual Standers). 14/33 (42.42%)eyes achieved “moderately impaired vision” (6/24 to 6/50 ) while 9/33(27.27%) eyes had “severely impaired vision “ (6/60 to 3/60). 1 (3.03%) eye has achieved only Light Perception and was placed in “Near Blind” category. (Table1) In group B only 2(6.45%) eyes achieved “(Near) normal vision” (6/18 or better), while 10(32.25%) eyes achieved “Moderately impaired vision” (6/24 to 6/50), and 18(58.06%) eyes had “severely impaired vision” (6/60 to 3/60). Only 1 (3.22%) eye was placed in “(Near) blindness” (1/60 or less) category. (Table,2) To compare the visual out comes in patient of group A and group B (Near) normal vision was achieved by significantly higher number of patients in group A than group B. 9(27.27%) eyes in group A patients achieved “(Near) normal” as compared to 2(6.45%) eyes in group B patients (P=>0.05). “Impaired vision” was achieved by 14(42.42%) eyes in group A patients and 10(32.25%) eyes in group B patients (P=>0.05). 18(58.06%) eyes in group B patients as compared to 9(27.27%) eyes in group A got “severely Impaired vision (P=>0.05). (Table, 3) Overall in our study we achieved (Near) normal vision in 11(17.18%) eyes (t=0.36), “Moderately impaired vision” in 24(37.5%) eyes (t=0.105 and in 27(42.18%) eyes (t=0.205) only ambulatory vision (severely impaired vision) was achieved.?








DISCUSSION

Several complication of advanced diabeticretinopathy can be treated surgically. Vitrectomy can clear media opacities, relieve traction on the retina possible. Removal of pre-macular vitreous may also improve diabetic macular edema. Instrumentation, understanding of patho-phsiology and surgical skills has improved surgical results12. As vitrectomy became safer indications and timing for surgery have considerably changed. The Diabetic Retinopathy Vitrectomy Study (DRVS) has recommended that vitrectomy should be advised for eyes with vitreous hemorrhage, which fails to resolve spontaneously within 6 months. Early vitrectomy (<6mo, mean 4mo) may result in a slightly greater recovery of vision in type I diabetics 9. This study was conducted with the objectives that either early vitrectomy is proportionally more effective in restoring of vision in patients with complications of diabetic eye disease or vitrectomy in later dates, that a significant time has been elapsed after the onset of complications of diabetic eye disease. Helbig. H stated that indication and timing for diabetic vitrectomy was increasingly important as the treatment of complications of diabetic retinopathy continue undergo modification and redefinition. He concluded that the most common indication for diabetic vitrectomy include i) severe non clearing vitreous heamorrhage; ii) tractional retinal detachment; iii) progressive fibro- vascular proliferation; v) Rubeosis iridis with vitreous heamorrhage 13. The improvement in visual acuity may be less satisfactory with longer duration of visual loss due to the complication of diabetic eye disease14. DRVS reported that after removal of longstanding vitreous hemorrhage, significant traction retinal detachment (sometimes in-operable) often was discovered. Surgeons had noted that once proliferative tissue was successfully removed and the posterior vitreous was completely excised, proliferation did not recur. Once the macula became detached by tractional forces, attempts at surgical re-attachment often failed to restore good vision. Therefore, where proliferation was severe and vision was still not significantly impaired, early vitrectomy had the potential to stop the proliferative process and preserve vision9. Machmer and Blankship (1981) reported visual improvement could be achieved in 59% of the cases where the posterior retina was attached but only in 25% where it was detached resulting in an overall major visual improvement in 46% of the cases15.In this study 6/18 or better vision was achieved by 9(27.27%) eyes of group A (early vitrectomy ) patients as compared to 2(6.45%) eyes of group B (late vitrectomy ) patients (P=>0.05). In DRVS, after 2years of follow up, 25% of early vitrectomy group had visual acuity of 10/20 (6/12) or better compared with 15% in late vitrectomy group9. Ishida and Takenchi (2001) evaluated the long term results of vitrectomy for complication of proliferative diabetic retinopathy, in patients with no macular detachment (group 1), macular detachment (group2) and tractional macular detachment (group 3). After five years follow up examination they found retinal re-attachment in 100% of eyes. The final visual acuity obtained was , 75% of the eyes had acuity of 0.1(6/60) or better in group 1, 24% in group 2 and 14% in group 3; 44% had acuity of 0.05 (3/60) or better in group 1, 2% in group 2 and 14% in group 3; and 1% had acuity of 0.05(3/60) 0r worse in group 1, 18%in group 2 and 0% in group 3 16. In this study postoperative visual acuity of 6/24 to 6/60 (moderately impaired vision) was achieved by 42.42% eyes in group A patients and 32.25% eyes in group B patients. Visual acuity of 6/60 to 3/60 was achieved by 58.06% eyes in group B patients and 27.27% eyes of group A patients. In this study considering the overall visual outcome 6/18 or better, visual acuity was achieved in 11(17.18%) eyes. Visual acuity of 6/24 to 6/60 was achieved in 24(37.5%) eyes and 27(42.18%) eyes achieved visual acuity of 6/60 to 3/60. Helbig and Kellner (1998) evaluated the functional results, risk factor and complication in 389 eyes, that had undergone vitrectomy. They found that after median follow up time of six months of surgery, 25% of the eyes had a visual acuity of 20/60 (6/18) or better, a vision less than 5/200 (1/60)was found in 25% of the eyes. Only 16% of the eyes with tractional detachment of macula had postoperativevision of 20/200(6/60) or better. They concluded that eyes with advanced stages of long standing tractional detachment of macula the functional prognosis was very poor due to the underlying micro vascular disease. In less advanced stages with vitreous hemorrhage and flat retina the risk of vitreous surgery was lower17. Diabetic person with sever vision loss from severe proliferative diabetic retinopathy are candidates for vitrectomy after vitreous hemorrhage and sever fibrous changes in retina 18. Surgery during the rapidly evolving proliferative and retracting process did not adversely affect the visual success rate when compared to previous reports on longstanding vitreous heamorrhage19. In cases in which vision loss occurred, pars Plana vitrectomy frequently can restore useful vision and reduce the risk of vision loss from traction retinal detachment 18. As discussed above in present study the result (in terms of visual outcome) of early vitrectomy were proportionally better in patients with complicated proliferative diabetic retinopathy as compared to the results of patients with vitrectomy done in later dateas.

CONCLUSION 

Vitrectomy for complications of proliferative diabetic retinopathy is valuable in improving the patient’s visual acuity. Any delay in surgery for complications of diabetic retinopathy can cause such complications which are difficult to treat. Even after treatment, good results cannot be obtained as with early vitrectomy. Earlier the presentation, better options for treatment and better visual outcome. 

Conflict of Interest: The authors have no conflict of interest and is not supported or funded by any Drug company or any other source.


1. Al Quraan 2:29
2. A.Samad Shera, Abdul Basith, Asher Fawad. Pakistan National Diabetes Survey: Prevalance of glucose intolerance and associated factors in the Punjab Province of Pakistan. Primary Care Diabetes 2010; 79-83.
3. Diabetes Mellitus (editorial). Pak J Ophthalmol 2002; 18:90-1.
4. The Diabetic Retinopathy Study Research Group. Preliminary report on effects of photocoagulation Therapy. Amm J Ophthalmol 1976; 81: 383-97.
5. Early Treatment of Diabetic Retinopathy Study. Effects of aspirintreatment on biabetic retinopathy. ETDRS Report No.8. Ophthalmology 1991; 98: 757-65.
6. Kanski’s. Clinical ophthalmology; A systemic approach. 8th ed. ELSEVIER Limited, 2016; 520-37.
7. Machemer R, Parel JM, Buttner HE, A new concept for vitreous surgery. Amm J Ophthalmol 1972; 74: 1022-35.
8. Thomas D. Duane, William Tasman, Edward A Jaeger. In: Duane’s Ophthalmology. Vol. 9. Philadelphia: Lippincott Williams & Wilkin; 2011; 715-32.
9. Diabetic Retinopathy Vitrectomy Study Research Group. Early vitrectomy for sever vitreous hemorrhage in diabetic retinopathy. Four year results pof a randomized trial. DRVS Report No.5. Arch Ophthalmol 1990; 108: 958-64 .
10. Haider SA. Vitreous haemorrhage. “Wait and see” Pak J Ophthalmol 2003; 3 : 60-3.
11. Visual Standards, Aspects and Ranges of Visual loss with emphasis on population survey. Reported by International Council of Ophthalmology at 29th International Congress of Ophthalmology Sydney Australia April 2002: 6-7.
12. DK Newman. Surgical management of the late complication of prolifretive diabetic retinopathy. Eye 2010; 24 : 441-49.
13. Helbig H. Surgery for diabetic Retinopathy. Ophthalmologica 2007; 221: 103-111.
14. Yorston D, Wickham L, Benson S, Bunce C, Sheard R, Chartaris D. predictive clinical features and outcomes of vitrectomy for proliferative Diabetic retinopathy. Br J Ohpthalmol 2008; 92: 365-368.
15. Machemer R, Blankenship G. Vitrectomy for proliferative diabetic retinopathy associated with vitreous hemorrhage. Ophthalmology 1981; 88: 643-6.
16. Ishida M, Takenhi S. Long term results of vitrectomy for complications of proliferative diabetic retinopathy. Ophtalmology 2001; 105: 457-62.
17. Helbig H, Keuner U, Bronfild N, foester MH. [ Abstract of vitrectomy in diabetic retinopathy: outcome, risk factors, complications, Klin Mona Trbl Agenheiked. 1998 May; 212: 339-42] [ cited 2017 Aug 19] available from www.neb.nih.gov/ PubMed.
18. Airgy PG, Cavallerano J. the role of vitrectomy for diabetic retinopathy. J Am Optom Assoc 1998; 69: 733-40.
19. Aaberg TM. Clinical results in vitrectomy for diabetic tractional retinal detachment. Am J Ophthalmol 1979; 88: 246-53.