Findings from a study published in the American Journal of Ophthalmology compared the clinical outcomes of early pars plana vitrectomy (PPV) versus delayed PPV in patients with a first episode of vitreous hemorrhage (VH) secondary to proliferative diabetic retinopathy (PDR).
Give me some background.
Traditional management approaches for VH primarily focus on panretinal photocoagulation (PRP) in visible areas of the retina.
- For denser VH: Standard management is to wait for spontaneous clearance before proceeding with further PRP and vitrectomy for cases without spontaneous clearance after at least 3 months or recurrent hemorrhages in a shorter period.
However, early PPV is emerging as an alternative option for VH to allow for faster visual rehabilitation.
- Further: Previous small sample-sized studies have demonstrated reduced risks of intra- and postoperative complications with early PPV.
Now talk about the study.
In this retrospective comparative study, researchers analyzed the data of consecutive patients with type 1 or 2 diabetes diagnosed with new-onset VH secondary to PDR who underwent PPV at a Moorfields Eye Hospital between December 2014 and December 2016.
They collected demographic and clinical features such as best-corrected visual acuity (BCVA, measured in logMAR and converted to Snellen) at baseline and 12 months.
Patients were divided into two groups based on the timing of their surgery:
- Early PPV (≤ 6 weeks)
- Delayed PPV (> 6 weeks)
What were the exclusion criteria?
Patients were excluded if they reported:
- Prior vitrectomy
- Iris neovascularization
- Neovascular glaucoma
- Macular edema
- Presence of tractional/rhegmatogenous retinal detachment
Main outcome measures?
These included:
- BCVA at 12 months postoperatively
- Reoperation rates
- Severity of complications
Findings?
In total, 178 eyes (48 early PPV, 130 delayed PPV) were analyzed and the mean (standard deviation [SD]) number of weeks before surgery was:
- 3.36 (SD 1.6) for the early PPV group (p < 0.0001)
- 22.56 (SD 17.23) for the delayed PPV group (p < 0.0001)
Baseline BCVA prior to PPV was similar between groups (p = 0.08); however, at 12 months the early PPV group had significantly better BCVA (20/50 vs. 20/93.5, p = 0.02).
Tell me more.
Patients without posterior vitreous detachment (PVD) on ultrasound or optical coherence tomography (OCT) demonstrated more pronounced BCVA differences in the early PPV group than the delayed PPV cohort (early PPV: 20/40 vs. delayed PPV: 20/100).
The early PPV group had fewer sight-threatening complications (p = 0.005) than the delayed PPV group.
Multivariable logistic regression analyses identified significant predictors of better visual outcomes, such as:
- Initial BCVA
- Early PPV
- Absence of preoperative panretinal photocoagulation (PRP)
- Patients who underwent preoperative PRP had ~3.6 times higher odds of moderate visual impairment than those who had intraoperative PRP
Expert opinion?
The higher rate of visual impairment in patients with preoperative PRP may be explained by the “angiofibrotic switch,” which occurs when the balance between VEGF and connective tissue growth factor (CTGF) reaches a critical threshold.
- What causes the switch: Patients with active neovascularization due to PDR may experience a sharp decline in VEGF levels due to anti-VEGF or PRP treatment.
This switch may also induce a shift from a pro-angiogenic to a pro-fibrotic state that can lead to excessive fibrosis and potentially result in visual impairment, explained the study authors.
Anything else?
They added that a thickened posterior hyaloid in patients without PVD and recurrent episodes of VH may exacerbate fibrosis—leading to the formation of tractional membranes and tractional retinal detachment (TRD) as well as causing worsening visual outcomes.
Take home.
These findings indicate that early PPV significantly improves visual outcomes and reduces severe complications in patients with VH secondary to PDR.
As a result: This supports the benefits of early surgical intervention to enhance long-term visual prognosis in these patients.
Next steps?
A randomized clinical trial with a larger sample size is warranted to further investigate these results, the study authors noted.