Risk factors for CME due to prostaglandin eye drops include a surgical history of glaucoma operations, aphakia, complicated cataract surgery, scleral buckling, and vitrectomy, as well as a history of uveitis and other retinal diseases. Patients without risk factors for developing the condition are rare.1
In terms of the prevalence of CME, Wand et al reported that two of 38 high-risk cases (5.3%) developed clinical CME.4
Meanwhile, Furuichi et al found that none of the 68 cases without any of the reported risk factors developed clinical CME.11
In cases without known risk factors, CME can appear within 2–3 months of surgery.10
Meanwhile, in high-risk cases, CME can even appear several years after the surgery.1
In cases without the known risk factors for CME, the condition may develop because of temporary damage to the blood–aqueous barrier immediately after surgery. In cases involving known risk factors, the damage to the blood–aqueous barrier is protracted, resulting in the continuance of conditions that lead to CME in the long term.14
Case one presented CME while undergoing benzalkonium chloride-free travoprost treatment. Miyake et al reported that preservatives in the prostaglandin eye drops have a greater influence on the development of CME when compared to the base compound.15
Additionally, Watanabe et al reported CME cases that developed when latanoprost treatment was initiated after 3 years of treatment with preservative-containing unoprostone.7
CME has similarly been reported when latanoprost was added to a drug regimen that already included several types of eye drops containing preservatives.2
While preservatives may promote latanoprost-induced CME, the preservatives alone do not provide a sufficient explanation for the development of this condition. Esquenazi studied a case of CME induced by benzalkonium chloride-free travoprost.9
In case one of this study, benzalkonium chloride-free travoprost appears to be the cause of the CME. No other eye drops were used during the treatment, and the patient had no underlying diseases (eg, diabetes) that could have caused CME.
Because the risk of CME is high immediately after cataract surgery, NSAIDs should be used along with a prostaglandin eye liquid.16
In case one, the administration of diclofenac was discontinued 6 months after surgery since it was determined that the danger of developing CME had decreased, although the treatment with travoprost was continued. No recurrence has been observed for a period of 2 years. In case two, treatment with the diclofenac eye drops and latanoprost was continued because it was believed that the damage to the blood–aqueous barrier would be protracted. No indications of CME were observed 3 years after surgery. Wand and Gaudio reported two cases in which CME treated with NSAIDs did not recur after unoprostone and bimatoprost treatment was resumed.13
Further, this group reported one case in which CME did not recur after latanoprost treatment was resumed.4
Meanwhile, Callanan et al reported one case in which CME not treated with NSAIDs recurred after resumption of latanoprost treatment.3
Prostaglandin has no systemic side effects and is currently the most effective drug as an eye liquid. When possible, the use of this drug should be resumed after a certain period of time. In certain cases, the concomitant use of NSAIDs and prostaglandin eye drops can be greatly beneficial to patients.
Subtenon injection of triamcinolone is considered the standard treatment for CME caused by diabetic retinopathy, retinal vein occlusion, uveitis, or other conditions. However, no studies have been conducted on the effectiveness of this treatment for CME caused by the use of prostaglandin eye drops. Several treatment options are available for prostaglandin-induced CME, including NSAIDs, steroids, dorzolamide hydrochloride eye drops, and oral acetazolamide; however, in many cases, recovery can take as long as 1 month or more.3
Triamcinolone treatment poses the risk of the typical side effects caused by steroids, but the risk of infection should not be a concern if its usage is avoided immediately after the surgery. Case one had no surgical complications and presented CME during the use of travoprost; therefore, aggressive care was chosen. Case two presented blindness in the right eye, and there was a strong desire for a quick recovery of the left eye. The authors believe that in such a case, subtenon triamcinolone injection is the selectable course of treatment.