This review article discusses the importance of delaying lens removal as long as possible after vitrectomy in order to slow ocular hypertension and glaucoma progression.
The authors found that increased oxygen in the anterior chamber angle and increased risk of glaucoma are associated with vitrectomy and cataract surgery, African ancestry and having a thinner cornea.
Since tissue damage can occur when oxygen levels are increased in the eye, they say that preserving the tissues that maintain intraocular oxygen gradients should become a goal of ophthalmic surgeons.
They note that oxygen levels in the eye are generally low and tightly regulated. However, age-related degeneration of the vitreous body or removal during vitrectomy exposes the posterior of the lens to increased oxygen, causing nuclear sclerotic cataracts.
Lowering oxygen in the vitreous, as occurs in patients with ischemic diabetic retinopathy, protects against cataracts after vitrectomy.
Cataract surgery and vitrectomy increase oxygen levels at the trabecular meshwork and with it the risk of open-angle glaucoma.
They say that preservation of the vitreous body and the lens, two important oxygen consumers, would protect against nuclear sclerotic cataracts and open-angle glaucoma.
They note, however, that patients who already have significant visual impairment from cataracts are good candidates for phaco-vitrectomy.
On the other hand, patients who have relatively clear lenses, especially if they have changes in their optic nerve head that make them glaucoma suspects or if they already have slightly elevated IOP, would be better served by delaying cataract surgery for as long as possible after vitrectomy.
They add that an alternative approach would be to find ways to protect the lens from exposure to excess oxygen after cataract surgery, thereby preventing or slowing nuclear sclerotic cataracts. These approaches might include reducing oxygen levels in the perfusion fluid used during vitrectomy, replacing the vitreous gel after vitrectomy or restoring the structure of the remaining vitreous after limited vitrectomy.