Dexamethasone implant injection is definitely an unpleasant experience for patients and it was our awareness that many suffer pain in variable degrees. Pain at the site of injection can cause distress for patients which may result in reduction in patient compliance with the treatment [14, 15]. In view of this, we decided to test the effectiveness of nepafenac in terms of reducing the pain after the injection as nepafenac has been proven to have an acceptably great margin of safety and a very good analgesic effect in many ocular surgeries [6, 7].
There are several studies in literature evaluating pain either during or after anti-vegf injection however there is still controversy regarding the most effective procedure of anesthesia for lessening pain related avti-vegf injection [4, 16–18]. There are also limited studies that evaluates pain during Ozurdex injection [10]. Differently, in present study we aimed to investigate reducing the ocular pain especially after Ozurdex injection. In this way we may be able to encourage the patients to the treatment who will need multiple injections to get a desirable treatment effect [17–19].
In the present study nepafenac demonstrated a significant reduction of pain after Ozurdex injection at 6 and 24 hours compared with placebo. Although statistical significance was not reached, there was a tendency to less pain in the nepafenac group at 1 hour after the injection. Following topical application the onset of nepafenac activity was reported to be around 15 minutes and duration of action was greater than 8 hours [20].The rapid onset of activity, and a highly effective non-selective cyclooxygenase inhibitor feature of nepafenac may contribute to a significant reduction of the pain at 6 hours [8].
Ogurel and colleagues [10] reported that topical 0.1% nepafenac had an additive analgesic effect during intravitreal Ozurdex injection when combined with topical anesthesia. Makri and colleagues [12] reported that a single drop of nepafenac before intravitreal injection was effective in reducing injection-related pain immediately and up to 6h after the injection which supports our results.
Ozurdex is in an applicator with a relatively large 22-gauge needle compared with other needles. Therefore, patients may experience more pain than other procedures performed by a smaller sized needles [21, 22]. In a large trial, Ozurdex was observed to be well tolerated and eye pain was reported as the third most seen adverse effect [3]. However in a study, an interesting outcome was added to the literature that intravitreal injection of Ozurdex was not associated with more pain than bevacizumab injections, despite larger needle gauge and longer scleral route [4]. Similar to the latter study a very recent study by Ertan and colleagues [23] supports this article as they concluded that there was no significant difference in pain between intravitreal injections of dexamethasone implant, ranibizumab or aflibercept.
Interestingly, the mean VAS pain score at 6 hours in the placebo group was slightly higher than those at 1 hour after the injection. This can be attributed to ocular surface irritation caused by topical application of povidone–iodine and topical anesthetics during the procedure [24, 25]. We observed that the pain scores in both nepafenac and placebo groups at 1 hour after the injection were similar which may also be attributed to the corneal epithelial damage.
Indeed, data concerning pain after intravitreal Ozurdex injection is limited, however, a study, with the similar application technique of the drug, by Urlich demonstrated that a single drop of nepafenac reduced the ocular discomfort after intravitreal injection [24]. Although the results of our study were similar to those reported by Urlich, they were not completely consistent. The pain scores were also lower at 24 hours in that trial; however, no statistical significance was reached, probably due to the investigator using systane ultra as a placebo. Specifically, systane ultra provides sustained lubrication to the eye and protects the ocular surface from further damage while the surface epithelial cells undergo repair and renewal [26]. We, therefore, avoided using any artificial tears as a placebo to minimize potential bias.
A limitation of our study includes the difficulty of objectively comparing pain levels. However, the study design and administration of the Ozurdex by a single ophthalmologist are strengths of this study.
In conclusion, nepafenac ophthalmic suspension 0.1% was effective in reducing pain after intravitreal Ozurdex injection and may offer patient comfort and patient adherence to the treatment.