FOURsight – eye problems

Dr Jiten Mistry describes four eye problems to look out for during oncology treatments.

You can listen to this article below, or by using your favourite podcast player at pod.link/oncologybuddies

Eye health can easily be overlooked when faced with a life-threatening diagnosis such as cancer. Certain cancers, and even cancer treatments, can potentially have a negative impact on your ocular health and it’s important to be aware of them. Early detection and treatment of eye complications in cancer patients can be sight-saving and improve overall quality of life.

The various cancer treatment modalities (steroids, radiation, chemotherapy, immunotherapy) can all have ocular complications. These can be summarised in four easy-to-remember groups.

1. Blurry eyes

Changes in eyesight, such as blurring, double vision, distortion, or loss of part of your field of vision, are serious complications that require urgent attention by an eye specialist (ophthalmologist).

Certain chemotherapy drugs can be toxic to the retina or optic nerve. Tamoxifen is a commonly used adjunctive therapy in hormone receptor-positive breast cancers. In rare circumstances it may cause toxicity to the optic nerve, pigmentary changes or crystal formation, swelling of the retina, and cataracts (opacification of the lens).

Cataracts may develop due to chemotherapy, steroids, or following radiation to the head and neck region. Fortunately, cataracts can be treated with a minimally-invasive lens replacement procedure. Excellent advances in surgical devices and instrumentation means that most patients enjoy good vision after cataract surgery.

Cancers of the eye often present with visual disturbance. The most common primary ocular malignancy is uveal melanoma. The most common secondary cancer to metastasise to the eye is breast cancer (females) followed by lung cancer (usually males). Certain brain tumours, both benign and malignant, may cause direct compressive injury to the optic nerves or other parts of the visual pathways.

Radiation for orbital or nasopharyngeal tumours also poses a risk of radiation retinopathy or optic neuropathy.

Vision-related complications during oncology treatments are serious and it’s critical that you inform your treating oncologist right away if you experience any visual disturbances.

2. Red eyes

There are many novel immunotherapy drugs available to treat various cancers these days. Certain immunotherapy medications can cause inflammation of external eye structures (conjunctivitis, blepharitis, scleritis) or internal eye structures (uveitis). This can present as painful, red, swollen eyes with photophobia (light-sensitivity). Some examples of immunotherapy medications that can potentially affect the eyes are ipilimumab, pembrolizumab and nivolumab.

3. Dry eyes

The delicate tissues on the eye surface, including key glandular tissues involved in tear production, are particularly vulnerable to damage by chemotherapy drugs. Dry eye symptoms are the most common ocular complications experienced by patients undergoing chemotherapy. These include grittiness, burning, redness, or scratchiness of the eyes. Dry eye symptoms can often be exacerbated by loss of eyelashes or misdirected eyelashes.

In patients undergoing bone marrow transplantation, a very specific condition called graft-versus-host disease may develop in which the donor’s immune cells may start to target the host’s tissues. Subsequent damage to the ocular surface and tear glands will cause significant dry eye disease with debilitating ocular pain and blurry vision.

4. Watery eyes

In contrast to dry eyes, some patients may experience watery eyes (epiphora) due to blockage of the ducts that drain tears from the eyes into the nose. Docetexal and 5-FU are two commonly used chemotherapy agents that may cause scarring and obstruction of the lacrimal drainage apparatus.

Visit an ophthalmologist

Where possible, it’s best to see an ophthalmologist before starting any oncology treatment and then every 12 months thereafter if no ocular complications are encountered. Ask your oncologist to refer you to an ophthalmologist if you don’t already have one. An ophthalmologist will perform a detailed examination of the front and back of the eye, including specialised tests and imaging, to establish a baseline.

Most eye complications during cancer treatments are manageable. Rarely, sight-threatening complications may prompt the decision to stop the offending cancer treatment. This should always be a joint decision between patient, oncologist, and ophthalmologist.

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