Drugs that affect the macula - What you need to know

 Many of our patients take medications that can have a negative or positive impact on vision via their effects on the macula.  Here we review the main players and what you need to watch out for.

Plaquenil

This anti-inflammatory drug is most commonly used to treat rheumatoid arthritis and systemic lupus. It can cause retinal toxicity associated with irreversible even progressive vision loss. It’s mechanism of action is unknown.   Screening for toxicity before the classic bull’s eye maculopathy is present is a medical-legal responsibility.  Examinations should include amsler grid testing, fundus photo’s, a 10-2 visual field with red target or equivalent and color vision testing every 6-12 months.  When toxicity is suspected but uncertain, a flourescein angiogram may reveal the classic maculapathy and the EOG are suppressed.   The relatively “safe dose” appears to be less than 6.5 mg/kg of hydroxychloroquine for less than 5 years. In practical terms, there risk is high in patients taking 400mg/day and weighing less than 135 lbs, having greater than 5 years of continues use, those with liver or kidney failure and elderly patients with AMD already compromising macular function. 

Niacin and Nicatinamide

Both of these drugs may be used for their cholesterol lowering effects in relatively high doses.  A non-leaking CME results which is generally reversible but associated with central vision loss.  Recent studies suggest a beneficial effect on age-related memory loss and dementia as well as cystic acne so the incidence of toxicity is on the rise.

Amniodarone

This antiarrythmidc drug is used to regulate the heart in patients with abnormal cardiac rhythms which, in most cases are life threatening.  In addition to t he classic, normally benign, corneal vertisellata seen in nearly all patients taking the medication, in rare cases macular crystals can form with a reduction in macular function.  A few suspected cases of optic nerve toxicity have also been reported.

Ethambutol

Tuberculosis has increase in recent years with an increase in resistance as well.  Multi-drug resistance has also been observed.  Ethamultol is a common drug used in combination for treatment of TB.  The drug can cause optic neuropathy and patients must have a baseline visual field and disc photos with follow-up comprehensive eye exam every 3-4 months or sooner if any color vision loss or loss of light sensitivity is noted by the patient.  Toxicity may be partially reversible.  

Interferon

Now used in increasing frequency for management of Hepatitis C, baseline retinal exams are critical along with follow-up checks every 4-6 weeks or sooner for any reported vision loss.  Common findings including retinal hemorrhages cotton wool spots and rarely macular edema.

 Anti-Psychotics

Certain phenothiazines used to treat psychosis and schizophrenia can cause retinal toxicity. Mellaril (thiorisazine) and Torazine (chlorpromazine) carry the highest risk and are less commonly used today.  Acute toxicity associated with night and color vision problems and long term use leads to a diffuse but geography atrophy of the RPE with peripheral and central field loss that is irreversible.  Screening tests include photos and visual fields.

 Sildenafil (Viagra)
This phosphodiesterase inhibitor which can affect the photoreceptors directly and alter a patients perception of color (blue or purple haze may be seen) and increase their light sensitivity.  Of greater concern is the potential to cause non-arteritic ischemic optic neuropathy.  This later effect is thought to occur in susceptible individuals who may have erectile dysfunction due to micro vascular disease (e.g., diabetics).  Until further investigations and clinical data allows for definitive conclusions, current recommendation based on weak anecdotal evidence is that patients with a history of monocular NAION be cautioned that Viagra may increase the risk of NAION in the fellow eye.

Tomoxafen

This drug is used to prophylaxis as well as treat patients with breast cancer. Ocular side effects consist of crystalline retinopathy, corneal deposits, and optic neuritis and occur in 1-10% of patients.  It may cause nerve fiber degeneration and discontinuation may not restore vision.   A baseline central visual field as well as fundus photos and daily Amsler grid testing at home are recommended. 

ACE inhibitors

Unlike the above medications, ACE inhibitors may actually have a beneficial effect on patients with macular diseased, particularly those with diabetic macular edema.   In the same way that ACE inhibitors improve renal function buy increasing blood flow, they can achieve a similar effect on the retinal circulation and by this mechanism and perhaps others improve clearance of fluid from the macula in diabetic patients.

 Systemic drugs can be toxic to the macula and in some cases beneficial.  Be aware of the meds and when patients present with a visual complaint review their med lists for possible agents that might affect vision.  While the above affect the macula directly, many drugs also have anti-cholinergic side effects that can cause dryness and blurred vision.  When vision loss occurs or toxicity is suspected, consider a retina consult. 

Ron P. Gallemore, M.D, Ph.D.

Founder and Director

Retina Macula Institute and the

Retina Macula Research Center

South Bay 310-944-9393

Los Angeles 310-466-9393