Dialysis and Vision: Update on Risks

Download PDF

The dangers of intradialytic hypotension cannot be overstated, given that it is a risk factor for dialysis-asso­ciated nonarteritic anterior ischemic optic neuropathy (DA-NAION), which poses a more serious threat to vision than does typical NAION. In an attempt to alert ophthalmologists—and their internal medicine and nephrology col­leagues—to the dangers of DA-NAION, researchers at the University of Toronto recently published a case series and review of the literature.¹

A time to worry. “Typically, doctors are scared of hypertension—but there are times to be scared of hypotension,” said coauthor Edward Margolin, MD. “Patients on dialysis have poor autoregulation of their vasculature. Thus, they have a difficult time responding to any drop in blood pressure—and we presume it is the hypoperfusion of the optic nerve head that leads to DA-NAION in these patients.”

He emphasized that clinicians “need to understand that if a patient is on dialysis, the goal is to prevent hypoten­sion.” Moreover, he said, “The patient who already suffered an episode of DA-NAION is at high risk of recurrence in the fellow—and even the same—eye.”

Delving into the literature. In their review, Dr. Margolin and his colleagues found reports of 31 patients (50 eyes) with DA-NAION associated with intra­dialytic hypotension.

Patient characteristics. The mean age at presentation was 47.7 years of age, and 18 of the patients (58.1%) were male. Nineteen (61.3%) had bilateral involvement; this was simultaneous at presentation in seven (22.6%) and sequential in 12 (38.7%).

Of note, three patients (9.7%) expe­rienced a recurrence within a previously affected eye.

Visual outcomes. Vision loss was severe, the researchers found: Present­ing visual acuity (VA) was available for 44 eyes and was 20/200 or worse in 28 (64.6%). At final follow-up, VA was 20/200 or worse in both eyes of 19% of the patients.

In contrast, the researchers noted, visual outcomes of hand motion or worse are uncommon in typical cases of NAION.

How common a problem? “Depend­ing on the definition used, intradialytic hypotension could occur in 5% to 30% of all dialysis treatments,” the research­ers said. And from his own perspective, as a neuro-ophthalmologist in tertiary practice, Dr. Margolin said that he sees at least three or four patients with DA-NAION a year.

Contributing factors. Many factors contribute to intradialytic hypotension, the researchers noted, including rapid or excessive filtration, a rapid reduction in plasma osmolarity, autonomic neu­ropathy, and poor cardiac reserve.

An overview of management strategies. Although the ophthalmic literature includes cases of DA-NAION, management of intradialytic hypoten­sion is rarely covered in these reports, Dr. Margolin said. Thus, as part of their review, he and his colleagues included a discussion of steps that typically are taken by nephrologists to manage cases of intradialytic hypotension—and to prevent recurrent episodes.²

For instance, acute management in­cludes repositioning the patient in the Trendelenburg position and decreas­ing or holding the ultrafiltration rate. And prevention of recurrence involves a stepwise approach that comprises dietary and medication evaluations, among other strategies.

The bottom line. As an ophthal­mologist, Dr. Margolin said, “If you see NAION, determine whether or not the patient is on dialysis. If so, this is a person you need to worry about.” Further, he emphasized that ophthal­mologists need to communicate more broadly with their internal medicine and nephrology colleagues. “They need to understand that hypotension raises the risk of vision loss.”

—Jean Shaw

___________________________

1 Donaldson L et al. J Neuro-Ophthalmol. Pub­lished online Dec. 28, 2021.

2 Kooman J et al. Nephrol Dial Transpl. 2007;22(suppl 2):ii22-ii44.

___________________________

Relevant financial disclosures: Dr. Margolin—None.

For full disclosures and the disclosure key, see below.

• AI Model Successfully Diagnoses Cataract

• Racial Differences Emerge in Trabecular Meshwork