Sir,

The taxane class of drugs (eg, paclitaxel (Taxol), paclitaxel nanoparticle albumin bound (NAB) (Abraxane), docetaxel (Taxotere)) are microtubule-stabilizing agents that are used to treat numerous malignancies. Cystoid macular oedema (CME) without increased permeability is a rare side effect of these medications.1, 2, 3 In the following report, non-leaking CME secondary to paclitaxel–NAB was successfully treated with off-label use of topical 2% dorzolamide (Trusopt) in conjunction with cessation of the chemotherapy agent. A monocular treatment trial suggested more rapid resolution with dorzolamide compared with drug cessation alone.

Case report

A 59-year-old female with metastatic breast cancer presented with decreased vision following paclitaxel–NAB infusion. The visual acuity was 20/50 in both eyes. Fundus examination and diagnostic testing revealed bilateral non-leaking CME (Figures 1, 2a and b). A monocular trial of dorzolamide three times daily was initiated in the right eye. Paclitaxel–NAB was also stopped. Two weeks later, OCT showed marked reduction of CME (−114 μm) in the treated eye compared with the fellow eye (+28 μm) (Figures 2c and d). Given the improvement, bilateral dorzolamide was initiated. One month later, near-complete resolution of CME was noted in both eyes with visual acuity improvement to 20/20. (Figures 2e and f).

Figure 1
figure 1

Colour fundus photographs of the right (a) and left eyes (b) showing blunted foveal reflex and cystoid macular oedema. Fluorescein angiography of the right (c) and left (d) eyes confirming lack of leakage.

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Figure 2
figure 2

Optical coherence tomography (OCT) of the right (a) and left eyes (b) at time of diagnosis with cystic changes and a central subfield thickness (CST) of 464 μm and 435 μm, respectively. Two weeks following dorzolamide therapy in the right eye significant improvement of cystic changes is noted with a CST of 350 μm (c). OCT of the left eye at the same time point without topical therapy reveals slight worsening and a CST of 463 μm (d). One month after bilateral dorzolamide therapy, near-complete resolution of cystic changes are noted with a CST of 257 μm in the right eye (e) and 253 μm in the left eye (f).

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Comment

This report suggests a possible therapeutic efficacy for topical carbonic anhydrase inhibitors in the treatment of taxane-induced CME. Although the paclitaxel–NAB was stopped, topical dorzolamide resulted in a rapid decrease in oedema in the treated eye compared with the untreated eye. Once bilateral therapy was initiated, rapid resolution of oedema occurred. Though this report suggests a monocular response to dorzolamide therapy, asymmetric spontaneous resolution cannot be ruled out. Topical dorzolamide has been reported to decrease oedema for non-leaking CME from other conditions (eg, retinitis pigmentosa, X-linked retinoschisis).4, 5

As in this case, all previous reports of taxane-related CME have included cessation of the drug. In some cases, drug cessation may not be appropriate. Although systemic acetazolamide has also been reported for treating taxane-related CME, the topical use of dorzolamide may be a useful treatment alternative given its limited systemic side effects.2 Further research is needed to better understand the role for topical dorzolamide therapy in this condition. This report highlights the importance of ophthalmic evaluation of patients with visual complaints during chemotherapy.