Getting treatments to the light-sensing retina is one of the biggest challenges in eye research.

For conditions such as macular telangiectasia (MacTel) type 2 and Stargardt’s disease, this challenge is ever greater. Treatments must reach specific cells in the macula – the central region responsible for detailed vision – with high precision.

At CERA, Dr Sushma Anand is investigating whether the body’s own communication systems can be harnessed to overcome this challenge.

Her work focuses on exosomes as a natural and adaptable delivery system capable of carrying a wide range of treatments directly to affected cells in the retina.

“Exosomes are natural – produced by every one of our cells throughout our body, including in our eyes,” she says.

Although extremely small, exosomes can carry proteins, genetic material and other molecules from one cell to another.

Dr Anand describes exosomes as “a tiny delivery truck capable of transporting everything from small letters to large packages”.

Exosomes already play a key role in normal cell to cell communication and are therefore well tolerated by the body.

In the laboratory, the team can also modify them to interact with specific cell types in the eye, making them a promising natural delivery system for treatments targeting the retina.

Destination macula

Dr Anand’s research focuses on MacTel type 2 and Stargardt’s disease – two macular conditions for which there are currently no approved treatments.

MacTel type 2 is a rare, progressive macular disease that usually develops in mid to later adulthood and affects both eyes.

It involves changes to Müller cells in the macula, and defective delivery of energy to retinal cells, leading to gradual damage of light-sensing retinal cells and loss of central vision over time.

Stargardt’s disease is an inherited retinal disease that causes a gradual loss of central vision, often beginning in childhood or young adulthood.

It is caused by changes in genes that affect how retinal cells function, most commonly the ABCA4 gene, leading to progressive damage of the macula.

For people with MacTel, the retina has low levels of the amino acid serine, which is important for normal retinal cell function. In Stargardt’s disease, vision loss is usually caused by genetic changes that can be difficult to address using some existing treatment approaches.

A single natural delivery system could therefore carry very different types of treatments – from small molecules such as serine to larger genetic material.

Dr Anand and her team have shown that exosomes can be prepared, produced and engineered in the laboratory to carry potential treatments.

“We’re still at an early stage, but each step brings us closer to understanding how treatments might one day be delivered more effectively to the retina,” Dr Anand says.

Although Dr Anand’s research is focused on MacTel and Stargardt’s disease, she says its potential application may extend beyond these conditions.

“As we learn more, this approach could eventually inform the development of treatments for other retinal diseases.”

This work is supported by funding from the Macular Disease Foundation Australia.

This story was originally published in Creating the future in sight: Annual Review 2025.