Neovascular glaucoma following Nd:YAG laser capsulotomy: a rare complication in a postvitrectomised patient with diabetes

Abstract

To describe a case of acute-onset neovascular glaucoma (NVG) after a neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy in a diabetic vitrectomized eye of a patient with severe systemic and ocular comorbidities. A man in his 50s underwent a Nd:YAG capsulotomy for visually significant posterior capsular opacification with a previous history of vitrectomy with silicone oil in situ for diabetic retinopathy. He had systemic and ocular comorbidities implicating an advanced ischaemic status, both systemically and locally. Five days post Nd:YAG capsulotomy, extensive neovascularisation of the iris and angles was noted. Despite maximum antiglaucoma medication, an evisceration ensued due to intractable NVG. This case report highlights the importance of irreversible complications after a seemingly simple capsulotomy in eyes with advanced ocular conditions and systemic comorbidities necessitating extreme caution.

Background

Posterior capsule opacification (PCO) is a frequent complication following cataract surgery caused by remnant lens epithelial cell proliferation and migration.¹ Nearly half of these patients need a capsulotomy after 3 years of surgery due to visual complaints.¹ Neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy is a simple and inexpensive procedure that helps in quick recovery of vision and clearing of the visual axis.² When a PCO occurs in patients with diabetes, it can obscure the fundus view and thereby hinder optimal and timely management of retinal complications.³

Though Nd:YAG capsulotomy is a relatively safe procedure, it is associated with complications like damage to the intraocular lens, increase in intraocular pressure (IOP), iris haemorrhage, cystoid macular oedema, posterior vitreous detachment, retinal breaks/detachment and aqueous misdirection syndrome.⁴ Neovascular glaucoma (NVG) is an extremely rare complication, and we describe a case of acute NVG following Nd:YAG capsulotomy in a patient with diabetes who had previously undergone vitrectomy for persisting vitreous haemorrhage.

Case presentation

A 50 plus man with diabetes and hypertension, with poor systemic control, chronic renal failure on dialysis and cerebrovascular disease, a known smoker and a chronic alcoholic presented with decreased vision in the left eye. He had a previous history of non-arteritic ischaemic optic neuropathy in the same eye 6 months before this visit. On examination, the patient had early cataract with lasered proliferative diabetic retinopathy (PDR) and macular ischaemia in the right eye with a vision of counting fingers at 2 m. In the left eye, the patient had a posterior subcapsular cataract, lasered PDR and dense vitreous haemorrhage with a vision of counting fingers at 3 m. Since there was no improvement even at 8 weeks of follow-up, the patient was advised to undergo cataract extraction with an intraocular implantation, vitrectomy, endolaser and silicone oil tamponade. Silicone oil was used due to peroperative bleed and one-eyed status for earlier visual rehabilitation. The pseudophakic status facilitated adequate anterior vitrectomy.

Postoperatively, the vision in the left eye improved to 20/120 at 1 month. But a PCO caused a drop in vision to counting fingers at 3 m for which an Nd:YAG capsulotomy was done 2 months after surgery with some recovery. Five days later, the patient developed sudden blurring of vision with pain. He was noted to have neovascularisation of the iris, neovascularisation of the angle, anterior chamber cells and hyphaema, with an IOP of 64 mm Hg (figure 1).

Figure 1.

Neovascularisation of the iris noted after Nd:YAG (neodymium:yttrium-aluminium-garnet) capsulotomy.

Differential diagnosis

NVG secondary to:

• Diabetic retinopathy: no evidence of neovascularisation of the iris or angles noted prior to Nd:YAG capsulotomy.

• Ischaemic central retinal vein occlusion: clinical features not suggestive of vein occlusion.

• Ocular ischaemic syndrome: no anterior segment involvement noted.

Treatment

Anti-VEGF intravitreal injections.

Topical antiglaucoma medication.

Trans-scleral cyclophotocoagulation.

Outcome and follow-up

Despite treatment with anti-vascular endothelial growth factor (VEGF) intravitreal injections, maximum antiglaucoma topical medication and trans-scleral cyclophotocoagulation for the raised IOP, there was loss of perception of light 8 weeks later. The diabetic status remained uncontrolled throughout the follow-up.

Discussion

NVG is known to occur in diabetic retinopathy, ischaemic central retinal vein occlusion and ocular ischaemic syndrome, but has not been reported so far post Nd:YAG capsulotomy in a vitrectomised eye.⁵ Pars plana vitrectomy for PDR is associated with postoperative NVG in 4%–12% of patients.⁶ NVG postcapsulotomy in eyes with pre-existing ocular inflammatory has also been reported.⁷ Multiple risk factors have been attributed to the development of NVG after vitrectomy in eyes with PDR like advanced age, high glycosylated haemoglobin and fasting blood sugars, compromised renal status and ocular risk factors like preoperative elevated IOP, iris and angle neovascularisation, and the retinal tamponade used.⁸

Possible risk factors for NVG postcapsulotomy in our patient in the vitrectomised eye include superimposed systemic comorbid conditions like cerebrovascular disease and uncontrolled diabetes leading to diabetic nephropathy requiring renal dialysis. The concentration of VEGF in the vitreous cavity of patients with an ischaemic retina secondary to PDR as in our patient is much higher than that of the aqueous humour in ocular neovascularisation.⁹ There is a possibility of diffusion of VEGF and proinflammatory cytokines from the posterior to the anterior segment after a breach or contracture of the anterior hyaloid face during or after vitrectomy. The increased concentration of growth factors in turn stimulates the vascular endothelium of the anterior segment structures like the iris leading to neovascularisation.⁶ An intact posterior capsule acts as an anatomical barrier which confines the VEGF to the posterior segment.⁸ The laser capsulotomy potentially breaches the barrier and increases the risk of NVG in patients with advanced retinal disease.

This case highlights the rapid and aggressive development of NVG in a vitrectomised but seemingly quiescent eye. Despite being a simple procedure, Nd:YAG capsulotomy needs to be carefully considered and closely monitored in such vitrectomised eyes with advanced systemic comorbidities, but the prognosis remains poor. A careful biomicroscopy of the posterior pole, gonioscopy and retinal angiography before and after the procedure helps to diagnose and document ischaemia and neovascularisation to plan appropriate treatment and prognosticate.

Learning points.

• Nd:YAG (neodymium:yttrium-aluminium-garnet) capsulotomy, a fairly common procedure, needs to be carefully considered and closely monitored in high-risk eyes.

• Neovascular glaucoma in a vitrectomised but seemingly quiescent eye after capsulotomy is a possible complication which needs aggressive management.

• Irreversible complications after a seemingly simple capsulotomy in eyes with advanced ocular conditions and systemic comorbidities necessitate extreme caution.

• Adequate patient couselling about the risks and an informed consent prior to capsulotomy in vitrectomised eyes with advanced systemic comorbidities is advisable.

• A careful clinical examination before and after the procedure helps to monitor, plan appropriate treatment and prognosticate.

Ethics statements

Patient consent for publication

Obtained.