Part 2
Age related macular Degeneration:
The era of intravitreal Pharmacotherapy
A commentary about current practice patterns….
by Dr Chinmay Nakhwa
Laser and PDT destroyed retinal tissue and caused a lot of collateral damage, eventually leading to a large “ blind Spot” for the patient. The limitations of macular laser treatment and photodynamic therapy created a need for development of drugs which had a more physiological effect on the treatment of macular degeneration.
The idea for development of intraocular drugs actually came from the treatment for cancer. A class of drugs called “ Anti VEGF “ were being developed for the treatment of colon cancer. It was presumed that these drugs will reduce the blood supply to the cancer cells and hence kill them.
It was serendipitously noticed that a few patients who were given intravenous anti VEGFs had betterment of their macular degeneration too. Ophthalmologists then began experimentally injecting these drugs into the eye of the patients, off-label , and they had a remarkable effect on the patients’ vision : some of them actually improved their vision!
Efforts were also made to develop dedicated drugs which could be injected into the eye and companies spent a lot on R & D into developing such molecules
What Changed?
At the turn of the century, for the first time in history, there were drugs that could actually reverse the blindness caused by macular degeneration. This was a remarkable first, since the earlier treatments were aimed at purely stabilizing the vision and stopping further vision loss. Here was a therapy which could actually improve the patients vision if he was treated in time before retinal scarring occurred.
Moreover the action of these injections was almost instantaneous! Within 48 hours most patients could appreciate an improvement in vision clarity, reduction in the distortions, betterment of their contrast sensitivity and perceived ease in reading.
There was negligible down time for this treatment and even though it was an injection into the eye, the procedure wasn't painful for most patients. These factors greatly influenced the quality of life of the patients. Most were able to move about and even drive independently. They could read and write using reading glasses or common magnification devices.
Around this time, machines like the Optical Coherence Tomography ( OCT) scanner became commonplace in the eye doctors clinic. These machines could diagnose and document AMD in a very accurate and non-invasive manner and at a reasonable cost.
The accuracy of diagnosis and the ease of getting an eye injection popularized these treatments as “ day care procedures”.
What next?
For almost two decades since they were introduced in the market, these drugs have been the gold standard or the first line treatment for macular degeneration.
As the general longevity of the population increased, the incidence of macular degeneration has also increased. Without a doubt these drugs have greatly contributed in maintaining the vision and thus the quality of life in the silver age group patients
However these drugs do come with certain changes in practise patterns.
Firstly, since this is an intraocular procedure, it needs to be done in a sterile room, preferably an Operation Theater. There is a small risk of developing an eye infection if it is carried out under unsterile conditions.
Secondly, the companies providing the drug in India were multinational American countries which imported the drugs from the US through their Indian branches. Hence the cost of treatment was high to begin with.
Thirdly the treatment did not “ cure “ AMD. It wasn't permanent. This meant that the patient had to keep getting repeat shots in his eye every month.
This presented a unique challenge for the clinicians and patients. Here was a treatment which worked a near miracle in a potentially blinding condition but the cost of administering the treatment over many years was almost prohibitive. Add to that, if someone needed injections in both his eyes, the cost almost doubled! This wasn't all. The fact that the patient had to travel every month to the doctor’s clinic with an attendant added traveling costs and loss of daily wages for the attendant to the treatment cost.
A treatment in order to be effective, also has to be affordable!
Hence different injection regimens were studied and compared.
What if we injected the drug quarterly instead of monthly? What if we injected only if there was leakage seen on OCT scan ? What if we gradually increased the gap between injections? If these processes were effective, then the patient would in all likelihood maintain good vision with lesser number of injections.
Over the last 5 years there have been certain drugs launched which have a longer half life inside the eye. This also has reduced the number of injections needed per patient, thus reducing the overall cost of treatment.
Clinicians have gained a lot of experience combined with vast global data about the plan of management for macular degeneration and are in a formidable position to develop a customized plan for each patient.
Luckily for the patients, many indian companies are also manufacturing Anti VEGF drugs and this has made the overall treatment quite affordable.
Thanks to developing healthcare and health policies, life expectancy in India has increased from 48.4 in 1972 to almost 70 in 2019. With increasing longevity, geriatric illnesses have become more common as evidenced by a growing incidence of macular degeneration. Luckily modern technology and advances in pharmacology have enabled us to administer treatments which can maintain good vision even in patients in the silver age groups.
Hopefully with increasing insurance coverage within the Indian population, more people would be able to benefit from this treatment to preserve their eyesight.
Comments
Post a Comment