Ophthalmologists see advances in ocular drug delivery (ODD) are beginning to make a positive impact to administer drugs to the posterior segment of the eye. The method is considered to be safe and affordable to treat conditions like intraocular pressure (IOP), inflammation on the internal coats of the eye and retinal detachment, said Dr Thakur Raghu Raj Singh, director & president of Re-vana Therapeutics Ltd, Ireland.
 
Existing methods to administer drugs directly into the eye are associated with limited duration of drug action making it expensive, uncomfortable & painful to patients. The injection increases toxicity, intraocular pressure, retinal detachment and cataract among others, he said.
 
Visual impairment is a significant health problem worldwide. WHO estimates that globally 314 million people are visually impaired of whom 45 million are blind.
 
Ophthalmic drug delivery market is predicted to be worth of US$ 21.6 billion in 2018. It is a rapidly growing multi-billion-dollar market opportunity with sales surpassing for age-related macular degeneration(AMD): $600 million, diabetic macular edema(DME): $2 billion, uveitis/ocular inflammation: $ 500million, diabetic retinopathy: $1.5 billion & glaucoma: $5 billion. Currently over 1 lakh and 23,000 elderly patients are diagnosed with AMD annually in the US and UK respectively. Around 2 lakh individuals in the UK experience vision loss because of DME. But the challenge is to deliver drugs to eyes, he added.

Topical methods like eye drops or gels are appropriate to treat front of the eye diseases. Oral medications & intravenous administrations often fail to deliver adequate amounts of the drug into the eye and can present serious systemic effects, said Dr. Singh who is also a lecturer in pharmaceutics, McClay Research Centre, School of Pharmacy, Queens University Belfast.
 
Ocular drug delivery is tipped to be an advanced technology which is approved for sustained release drugs. Global leader, pSivida has developed three of the only four products approved by international regulators for the long-term, sustained release ocular drug delivery systems. However, disadvantages are high trauma to tissues, infection, retinal detachment, low patience compliance and high costs.

While there is a need for alternative technology, we see the intravitreal injection has remained as the ‘gold standard’ treatment modality to treat back of the eye diseases, IOP, endophthalmitis and retinal detachment. This mode of drug delivery is minimally invasive, easy to apply, accurate dosing, localized delivery and cost-effective, said Dr Singh who was in India recently for the IDBR seminar in Bengaluru.
 
Intravitreal injections are applicable to both front & back of the eye. The advantages is the drug delivery to the target tissue with high precision, overcomes barrier function of the eye and reduces pain associated with conventional needles, he said.