Cataract surgery is the most common medical surgical procedure, performed in the EU states in about 5 million individuals each year.
Despite the fact that it is now a fast and safe procedure, a variable degree of post-surgical inflammation can occur after surgery. Although such inflammation is, in most cases, self-limiting, the use of anti-inflammatory agents can quickly resolve it and prevent serious complications resulting from improperly controlled inflammation (such as cystoid macular oedema).
Consequently, the use of topical corticosteroids and/or non-steroidal anti-inflammatory drugs remains the mainstay in the post-surgical management of these patients.
Most common complications in cataract surgery
Apart from ocular inflammation, endophthalmitis is the most important complication of cataract surgery. Its severity depends on the virulence and quantity of pathogens that cause it. In particular, the Coagulase-negative staphylococci e S. Aureus are the most commonly isolated pathogens in this infection.
Furthermore, in the last decade, a major concern has been the high prevalence of infections due to S. Aureus methicillin-resistant (MRSA) and Coagulase-negative resistant staphylococci (MRCoNS). Therefore, currently, preoperative antisepsis of the periocular area with topical iodine-povidone and intracameral cefuroxime is generally implemented as standard for endophthalmitis prophylaxis. However, cefuroxime is not effective against methicillin-resistant strains.
Efficacy and safety of the dexamethasone/netilmycin combination in controlling ocular inflammation after cataract surgery
In clinical practice, topical antibiotics are often used both pre- and post-operatively to sterilise the ocular surface and prevent any access of microorganisms inside the eye. Topical antibiotics can be administered alone or in combination with corticosteroid drugs.
Fixed combinations of steroids and antibiotics have several advantages over the use of single components, such as better compliance, lower costs and reduction of the potential wash-out effect. The choice between the different available options depends, therefore, mainly on bacterial susceptibility to the antibiotic and the efficacy of the steroid included in the formulation.
One of the combinations available for controlling inflammation and infection after cataract surgery is dexamethasone/netilmycin.
The use of dexamethasone after cataract surgery is now well-established and the added value of this combination lies in the presence of netilmycin, a broad-spectrum antibiotic that is also effective against methicillin-resistant strains, ensuring complete sterilisation of the ocular surface in the immediate post-operative period, with negligible toxicity.
Indeed, since post-surgical infections are due to micro-organisms residing on the ocular surface, mainly Coagulase-negative staphylococci (in particular S. epidermidis) e S. Aureusit is essential to use antibiotics that are highly effective on these germs that, if not eradicated, can enter the eye and initiate infection.
For this reason, antibiotic treatment, if used, should begin on the same day as surgery. Netilmycin has been shown to be able to sterilise the eyelid margins and conjunctiva if it is administered prior to cataract surgery.
In addition, has been demonstrated that the bacterial flora on the ocular surface isolated from cataract surgery patients is highly susceptible to netilmycin and much less to other antibiotics.
It is important to emphasise that, regardless of their origin, isolates of S. Aureus e Coagulase-negative staphylococci are often characterised by methicillin resistance and multiresistance to different classes of antibiotics. A problem that is even more common in older patients, such as those operated on for cataracts.
Netilmicin, on the other hand, is effective on S. Methicillin-resistant Aureus (MRSA), Methicillin-resistant coagulase-negative staphylococci (MRCoNS) and Coagulase-negative staphylococci, whereas these micro-organisms show high resistance to fluoroquinolones, which should therefore not be the primary choice for infection control after cataract surgery, even considering the possible side effects.
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