Eye effects of cancer treatment: what to report, and to whom

An eye that never stops watering, vision that blurs, a gritty feeling under the eyelid: during cancer treatment, these discomforts are common and, for the most part, mild and reversible. A few warrant a visit within the following days, two or three call for prompt attention without delay, and how something feels is not enough to tell them apart: blurred vision might be nothing more than dryness, or the first sign of a problem affecting the cornea or the retina. This article sorts out what can be flagged at the next oncology appointment from what calls for a prompt examination.

AT A GLANCE

Why the eye is one of the sensitive organs

For three anatomical reasons. The corneal epithelium renews itself within days, which exposes it to drugs that target rapidly dividing cells. The retina is a nerve tissue supplied by very small-calibre vessels. Lastly, the pathways targeted by modern therapies are not unique to tumour cells: several are also active in the retina.

Two notions that are readily confused need to be kept apart: frequency and severity. The most frequent effects are the least serious. In an international database of medical records, mostly American, covering 41,020 patients treated with immunotherapy, the five most frequently recorded problems within the year were dry eye (2%), conjunctivitis (0.87%), blepharitis (0.51%), anterior uveitis (0.39%) and keratitis (0.38%): the surface of the eye, not the back of it.

One rule runs through everything that follows: an eye symptom never justifies stopping, spacing out or reducing a cancer treatment on your own initiative. The ophthalmologist looks, names the problem, assesses its severity and reports back; the decision rests with the oncologist.

WATERING EYES

An eye that never stops watering: think of the tear drainage pathway

This is the most classic reason for a consultation, and the most overlooked. Most often, tears are not being produced in excess: they are draining away poorly. The two best-documented drugs are 5-fluorouracil and docetaxel, a taxane used in breast and lung cancers. The mechanism: inflammation followed by narrowing of the canaliculi, the fine channels that drain tears towards the nose.

How often the drug is given matters, and so does the cumulative dose. A 2026 review distinguishes two situations: watering is common whatever the regimen, but the anatomical narrowing seen on catheterisation is observed almost exclusively in patients receiving docetaxel weekly, or treated for a long time in the metastatic setting. In patients treated every three weeks over a short period, obstruction is reported far more rarely; in the adjuvant setting, the authors know of no published case. An older review, from 2017, cites other drugs more rarely responsible: S-1, capecitabine, imatinib, topical mitomycin C, radioactive iodine.

Here is why it needs to be reported early. As long as it is only inflammation, eye drops are often enough. Under weekly docetaxel, as soon as a narrowing recurs or progresses, fitting a thin silicone tube keeps the canaliculus open and may prevent a permanent scar — and so avoid the heavier bypass surgery between the eye and the nose. A Japanese series of three patients is a reminder that not all watering signals an established obstruction: the patient whose lacrimal puncta were narrowed improved with probing and irrigation, and in the other two the watering resolved once docetaxel was stopped or with artificial tears. Three patients do not make a rule.

SURFACE

Dry eyes, irritated eyelids, lashes that grow longer

This is the common experience. The largest series of patients referred to ophthalmology under EGF receptor inhibitors — erlotinib and cetuximab, used in lung, colorectal and head-and-neck cancers — published, at the time, in 2013, found tear-film dysfunction and blepharitis, followed by eyelash abnormalities; only two patients had corneal erosion. Almost all were successfully managed, but the dryness and eyelash abnormalities persisted 6 to 17 months later.

This dryness is treated with the same tools as any other case of dry eye: preservative-free tear substitutes, eyelid hygiene, adjusting the environment — what to do about dry eye is covered in a dedicated article. The difference lies in the intensity and duration: treatment often needs to be stronger and longer.

Eyelash lengthening, or trichomegaly, always comes as a surprise. It does not require changing the treatment, but long lashes often irritate the eye and can damage the corneal surface: a published case under erlotinib is a reminder that it needs to be recognised to prevent severe complications such as a corneal ulcer. The 2025 European position paper groups conjunctivitis, Meibomian gland inflammation and dryness under the same heading. Other drugs have their own signature: blepharoconjunctivitis with oxaliplatin, cyclophosphamide, cytarabine and docetaxel; dryness with anastrozole, methotrexate and 5-fluorouracil. In practice, in the absence of pain, reduced vision and light sensitivity, none of this is urgent: it can be flagged at the next appointment.

CORNEA

Blurred vision and a foreign-body feeling: keratopathy from antibody-drug conjugates

These drugs combine an antibody, which recognises the tumour, with a cytotoxic molecule that it carries to it. Some also affect the corneal epithelium, where they produce tiny cysts visible on slit-lamp examination. Patients describe blurring vision, sensitivity to light, a gritty feeling. Common, often mild, and above all reversible.

The figures are as reassuring as they are cautionary. A 2025 review of conjugates used in gynaecological oncology reports surface problems in up to 56% of patients on mirvetuximab soravtansine and 50 to 60% on tisotumab vedotin, but fewer than 10% of these events reach grade 3 or above. The median time to onset is 1.3 months, with cases reported up to ten months: vigilance does not stop after the first few cycles. A safety analysis of 682 patients on mirvetuximab found blurred vision in 43% of patients, grade 3 or higher blurred vision in 5%, and treatment discontinued for an eye-related reason in 1%; 71% of blurred-vision episodes resolved completely.

With belantamab mafodotin, used in multiple myeloma, keratopathy is more pronounced: the final analysis of the DREAMM-2 trial ranks it among the most frequent grade 3 or 4 effects, occurring in 29% of patients at the 2.5 mg/kg dose and in 25% at the 3.4 mg/kg dose. This is an effect specific to this drug class, and it can be managed. In the DREAMM-2 trial, corneal and visual acuity examinations were carried out before treatment and then before each administration, and eye problems were managed with dose delays or reductions. For mirvetuximab, published recommendations call for an examination before the first cycle, then every other cycle for the first eight cycles, daily lubricating eye drops and, for periods, a corticosteroid eye drop. In both cases, do not stay silent about blurred vision: the point of delaying or temporarily reducing the dose is precisely to allow treatment to continue.

RETINA

A patch at the centre of vision: retinopathies from targeted therapies

MEK inhibitors, used in particular in melanoma and some lung cancers, cause fluid to build up beneath the central retina. A meta-analysis of 17 randomised trials estimates that adding one multiplies the risk of eye problems from all causes by 2.88 (95% confidence interval: 1.42 to 5.85), the risk of blurred vision by 4.10, of chorioretinopathy by 8.36, and of retinal detachment by 8.98. These are high ratios; the meta-analysis puts the added risk of eye problems at close to 7.3%, and clinical reviews describe these problems as common, but most often without any impact on vision.

What matters most is how these problems evolve. Clinical reviews describe effects appearing in the first days or weeks, most often without symptoms, resolving on their own without any change of dose; cases that genuinely threaten vision exist but remain rare. There is currently no recommendation for systematic screening, even though a baseline examination before treatment helps later to distinguish a pre-existing abnormality from a drug effect. Regular monitoring may be justified in at-risk patients — a history of eye inflammation or infection, known macular or retinal disease — and any visual disturbance during treatment should lead to a prompt ophthalmological examination. Of 61 patients treated with ERK inhibitors, the 20 who developed retinopathy had both eyes affected; visual acuity fell in 57.5% of eyes, mostly by one to two lines; the fluid reabsorbed without treatment, acuity then no longer differed significantly from its baseline value, and no patient had to stop or reduce treatment because of the retinopathy.

Other drug families have their own profile. FGF receptor inhibitors mainly affect the surface and the retina. ALK inhibitors produce flashes of light, accommodation problems and blurred vision, and a cataract is among the reported effects. A review of 174 patients treated with selinexor, combined with other cancer treatments, found an eye effect in 19.5% of them — blurred vision 12.6%, dryness 12.1% (mild in 10.9%), progression of an age-related nuclear cataract 4% — with none of these effects leading to treatment being stopped. The symptom that should never be overlooked remains distortion or disappearance of an area at the centre of vision.

HORMONE THERAPY

Tamoxifen: uncommon, but without recovery

This is one of the rare areas where screening takes precedence over waiting for symptoms: once visual acuity has fallen, stopping tamoxifen improves it little or not at all. Better, then, to pick up the signs before any discomfort appears.

On frequency, the two recent reviews do not agree, and this gap deserves to be known rather than smoothed over. The first records retinopathy in up to 12% of patients taking 20 mg a day for more than two years, of whom at most half develop a noticeable drop in acuity. The second gives a range of 0.9% to 12%, with time to onset ranging from three weeks to thirteen years. Some of this spread is probably down to methods: OCT can show abnormalities even in patients with no symptoms at all.

What is being looked for: fine crystalline deposits around the macula, macular oedema, hyperreflective deposits in the inner layers, sometimes small cavities at the centre of the fovea. A small comparative series, on 13 affected eyes, found on OCT an irregular foveal contour in all of these eyes and involvement of the outer retinal layers in 85% of them, and compares these images with those of another macular disease, type 2 macular telangiectasia. The monitoring proposed by the most recent review is an OCT scan every six months from two years of treatment onwards; the other review notes that no screening method is universally accepted. One last point: finding tamoxifen retinopathy does not mean stopping tamoxifen on your own. According to the most recent review, current management involves stopping tamoxifen to the extent that the cancer’s prognosis allows — an oncology decision, made with the ophthalmology report in hand. Other, non-cancer drugs can also affect the retina or the optic nerve: a separate subject, covered in a dedicated article.

IMMUNOTHERAPY

A red, painful eye during immunotherapy: uveitis

Immune checkpoint inhibitors release a brake on the immune system so that it attacks the tumour. The price is a range of autoimmune effects that can affect any organ, the eye included. Uveitis is the most characteristic eye problem: the eye becomes red, painful, bothered by light, vision clouds over, floaters appear.

Let’s put numbers on it, because the word alarms people more than it should. A study matching 71,931 patients treated with immunotherapy to just as many cancer patients who had not received it found the risk of uveitis multiplied by 2.39 (2.07 to 2.75): multiplied by 1.98 under anti-PD-1 alone, by 5.04 when anti-PD-1 and anti-CTLA-4 are combined. These multipliers apply to a rare event: a 2018 review puts the frequency of uveitis at around 1%, a 2024 review at between 0.3 and 0.4%, and the database cited above found 0.39% of anterior uveitis within the year, with a gradient depending on the drug class — 1.39% under combined anti-CTLA-4 and anti-PD-1 versus 0.14% under anti-PD-L1.

The outcome is fairly reassuring. A review of 126 published cases shows onset at a median of 9 weeks, with 83.6% of cases appearing within the first six months, and recovery to within one line of baseline acuity in the great majority of patients, with corticosteroids (as eye drops, local injection or systemically) and stopping the drug responsible. Dry eye, more mundane, affects 1 to 4% of patients in trials, almost always mild to moderate. Remember this: a red, painful eye during immunotherapy is not conjunctivitis until proven otherwise. Treatment is local first. The oncology recommendations reported in a 2024 review (ASCO, SITC, NCCN) keep immunotherapy going in mild forms and suspend it from the point forms become moderate; the decision rests with the oncologist.

RADIOTHERAPY

After radiotherapy: dryness first, the retina later

The eye effects of radiotherapy unfold on two different timescales. In the weeks that follow, it is the surface that suffers. A prospective study of 90 patients irradiated for a cancer of the upper aerodigestive tract found dryness in 48 of them, or 53.3%, with incidence increasing with dose. A smaller series, of 19 patients, describes dryness in 84.2% — including in several who received doses below the tolerance thresholds, which is why its authors recommend an ophthalmological opinion for every patient irradiated in this region.

The second timescale is measured in months and years. Radiation retinopathy is damage to the small vessels of the retina, which become progressively blocked: the result is ischaemia, oedema at the centre of the macula and reduced vision. It is seen mainly after irradiation of an intraocular or peri-ocular tumour, and its risk depends on the patient — diabetes and hypertension contribute to it — as much as on the irradiation itself.

The picture resembles that of diabetic retinopathy and is treated with the same tools: intravitreal anti-VEGF injections are the most strongly supported treatment for reducing the oedema and stabilising vision, supplemented if needed by a corticosteroid implant or photocoagulation of the ischaemic areas. OCT picks up early oedema before it is visible on fundus examination. A nuance against undue alarm: frequency depends on what was irradiated — in a series of 25 patients followed for a median of more than eight years after fractionated stereotactic radiotherapy for a tumour of the orbit considered benign, only 3 patients developed radiation retinopathy.

TRANSPLANT

After a bone marrow transplant: the dryness of ocular GVHD

This is the most severe dryness in this article, and the one that should not be mistaken for ordinary discomfort. After a stem cell transplant from a donor, the transplanted immune cells can recognise the recipient’s body as foreign: this is graft-versus-host disease. Its chronic form affects up to 70% of transplant patients, and eye involvement is one of its most frequent expressions.

It shows itself through marked dryness, Meibomian gland dysfunction, keratitis, conjunctivitis. What sets it apart from ordinary dryness is fibrosis: the lacrimal glands and the conjunctiva are not merely irritated, they are destroyed and scar over. Treatment therefore cannot be limited to a few drops of artificial tears, and it continues over the long term.

One point deserves to be known by every transplant patient: eye involvement can precede the disease’s other manifestations. An eye that becomes dry, red or sensitive to light after a transplant is therefore not a minor comfort issue, it is useful information for the haematologist. Diagnosis relies on international consensus criteria. There is no single protocol: management combines intensive lubrication, local anti-inflammatories, punctal occlusion and, in stubborn forms, autologous serum or scleral lenses.

WHAT TO DO

What to report, to whom, and how quickly

The timeframes below are markers of everyday practice, not thresholds drawn from the studies cited. The same day: sudden loss of vision, a red and painful eye with sensitivity to light, a veil or patch rapidly appearing at the centre of vision. In the coming days: persistent blurred vision, a foreign-body sensation with photophobia under an antibody-drug conjugate, constant watering under docetaxel, distortion of straight lines. At your next appointment: dryness, stinging, eyelids stuck together on waking, lashes growing longer, mild redness without pain.

Who should you tell? First, your oncology or haematology team: they know your protocol and the thresholds that trigger a delay in it, and they are the ones who will arrange the ophthalmological opinion at the right pace. If vision suddenly drops or the eye becomes red and painful, and the team cannot be reached that same day, seek an eye emergency department without delay. Do not save these symptoms for “after the treatment”: most of the problems described here are managed all the better for being caught early, and several become permanent if left to progress.

And what the ophthalmologist will not do: change your cancer treatment. They examine, measure, assign a severity grade, propose an eye treatment and write a report for the oncologist. The decision to suspend, reduce or continue treatment belongs to the latter: it involves weighing a balance of which the ophthalmologist holds only one pan. This division of roles most often makes it possible to treat the eye without cutting back the cancer treatment.

Frequently asked questions

Consultations in Cachan, Paris 13 and at the Sorbonne Saint-Michel practice (Paris 5th) · Tel. +33 1 45 47 08 11

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This article is intended for information purposes and does not replace a medical consultation. Indications, expected benefits and risks depend on each individual situation. For any question concerning your vision, consult an ophthalmologist.