1. JAMA Ophthalmology Journal Club Slides: Complications of Vitrectomy for Diabetic Retinopathy
Jackson TL, Johnston RL, Donachie PHJ, Williamson TH, Sparrow JM, Steel DHW. The Royal College of Ophthalmologists’ National Ophthalmology Database study of vitreoretinal surgery: report 6, diabetic vitrectomy. JAMA Ophthalmol. Published online November 19, doi: /jamaophthalmol

2. Introduction Background
Proliferative diabetic retinopathy can lead to vitreous hemorrhage and, in severe cases, tractional retinal detachment.
Persisting vitreous hemorrhage or tractional retinal detachment involving or threatening the macula are 2 of the most common indications for pars plana vitrectomy.
Objective
To prospectively audit the complications of vitrectomy for proliferative diabetic retinopathy and help establish benchmarks.

3. Methods
Study Design
Database study/audit using the Royal College of Ophthalmologists’ National Ophthalmology Database.
Data from electronic medical records (EMRs) prospectively transferred to the Royal College of Ophthalmologists’ National Ophthalmology Database.
Data from 13 UK vitreoretinal units using the same EMR (Medisoft Ophthalmology) from January 2001 up to November 2010 and from 3 vitreoretinal unit using a noncommercial EMR database (VITREOR) up to October 2013.
Participants
939 eyes from 834 patients undergoing primary vitrectomy for proliferative diabetic retinopathy, with or without delamination or segmentation.

4. Methods
Data Analysis
Diabetic vitrectomies were grouped into the following:
Vitrectomy without delamination (presumed diabetic vitreous hemorrhage).
Vitrectomy with delamination or segmentation (presumed tractional retinal detachment).
Primarily aimed to provide benchmark complication rates, but an exploratory visual acuity (VA) analysis was also undertaken.
The time to postvitrectomy cataract surgery was modeled using the Kaplan-Meier method.

5. Results Patient Demographic Characteristics
vitreoretinal operations were recorded in the Royal College of Ophthalmologists’ National Ophthalmology Database.
Of these, 939 were primary vitrectomy for diabetes (939 eyes; 834 patients; 64 surgeons):
420 (44.7%) were vitrectomy without delamination.
519 (55.3%) were vitrectomy with delamination or segmentation.
Median age, 58.2 years (interquartile range, years); 476 men, 358 women.
Type of diabetes mellitus:
Type 1: 237 patients.
Type 2: 405 patients.
Not recorded: 192 patients.

6. Results Surgical Technique and Anesthesia
Of 420 diabetic vitrectomies without delamination (among 408 patients; diabetic vitrectomy group):
18.1% underwent vitrectomy only.
81.9% had intraoperative laser surgery.
30.0% had intravitreal tamponade (88.9% gas or air, 11.1% silicone oil).
23.6% had phacovitrectomy.
General anesthesia was used for 35.7% and local anesthesia for 63.8%.
Of 510 diabetic vitrectomies with delamination (among 463 patients; delamination group):
8.1% underwent vitrectomy and delamination only.
91.9% had intraoperative laser surgery.
57.6% had intravitreal tamponade (80.9% gas or air, 19.1% silicone oil).
20.2% had phacovitrectomy.
General anesthesia was used for 64.2% and local anesthesia for 35.3%.

7. Results Intraoperative Complications
The overall operative complication rate was 22.7%.
13.1% for the diabetic vitrectomy group.
30.4% for the delamination group.
Iatrogenic tear (19.4%) and lens touch (1.4%) were the most common.
Further Pars Plana Vitrectomy
At least 1 further vitrectomy was performed in 13.5% of eyes after a median of 2.8 months from primary surgery.
11.7% for diabetic vitrectomy eyes.
15.0% for delamination eyes.
Retinal detachment occurred in 19 eyes (2.0%) after a median of 2.7 months.
1.7% following diabetic vitrectomy.
2.3% following delamination.

8. Rates of Postvitrectomy Cataract Surgery
Results
Rates of Postvitrectomy Cataract Surgery
The respective 1-, 2-, and 3-year cataract surgery rates were the following:
Diabetic vitrectomy (no delamination): 17.9%, 28.0%, and 44.1%.
Delamination: 21.2%, 34.6%, and 43.9%.
Use of gas during vitrectomy did not significantly affect subsequent cataract surgery.

9. Exploratory VA Analysis in Diabetic Vitrectomy Group (No Delamination)
Results
Exploratory VA Analysis in Diabetic Vitrectomy Group (No Delamination)
The median preoperative VA of the diabetic vitrectomy (no delamination) eyes was counting fingers.
The median best VA from 6-12 months after surgery was 20/63.
63.2% improved by more than 0.3 logMAR (approximately 2 Snellen lines).

10. Exploratory VA Analysis in Delamination Group
Results
Exploratory VA Analysis in Delamination Group
The median preoperative VA of the diabetic delamination eyes was 20/796.
The median best VA from 6-12 months after surgery was 20/63.
62.8% improved by more than 0.3 logMAR (approximately 2 Snellen lines).

11. Comment
Diabetic vitrectomy had an appreciable complication rate, particularly in the delamination group, with almost 1 in 3 operations associated with a complication. This is mainly related to retinal tears.
Nonetheless, most eyes had a measurable improvement in vision.
Despite the high tear rate in the delamination group, the postoperative retinal detachment rate was acceptable (2% in both groups).
Overall, 63% of eyes improved by at least 0.3 logMAR (approximately 2 Snellen lines) after surgery, with little difference comparing diabetic vitrectomy and delamination.

12. Comment
Strengths of this study include its large size, multicenter data collection, and prospective design. Database studies may be less subject to selection or publication bias than case series and more generalizable to real-world outcomes than randomized clinical trials.
The EMRs forced clinicians to record whether a complication occurred; combined with anonymized data collection, this may facilitate the recording of surgical complications.
The key limitation relates to lower levels of VA data completeness. This was probably because many centers used the EMR in the operating room but paper notes in the clinic. The VA results should be interpreted accordingly.
These results may not be generalizable to other countries, but the methods may serve as a template.
Future database studies might consider the collection of core, mandated data sets, including VA outcomes, in consecutive patients.

13. Conflict of Interest Disclosures
Contact Information
If you have questions, please contact the corresponding author:
Timothy L. Jackson, PhD, FRCOphth, Department of Ophthalmology, King’s College London, King’s College Hospital, London SE5 9RS, England
Conflict of Interest Disclosures
All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Johnston is the medical director of Medisoft Limited, which developed one of the EMR systems from which the data were extracted, and has received personal fees from Novartis and Bayer outside the submitted work. Mr Donachie received grants from Alcon-Thrombogenics outside the submitted work. Dr Williamson developed the other, noncommercial EMR system. No other disclosures were reported.