These are research studies done initially in a very small number of patients, and subsequently larger numbers before any therapy for diseases is approved by the regulatory authorities of the country.
www.clinicaltrials.gov gives a comprehensive list of clinical trials being conducted around the world in Inherited Retinal Diseases.
Foundation Fighting Blindness (www.fightblindness.org) is driving research into various treatments for inherited Retinal Diseases.
Gene therapy involves replacing the defective gene with a correct one that is encapsulated within a viral capsid. Once injected, the virus replicates allowing for delivery of the corrected gene. Given that the pathway is different for each genetic mutation, gene therapy is an expensive treatment.
Several clinical trials are underway to treat various inherited retinal diseases through gene therapy. For more information click here
LUXTURNA™ (voretigene neparvovec) is an approved gene therapy for patients with two mutations in a gene called RPE65. Mutations in RPE65 may cause either Leber Congenital Amaurosis or Retinitis Pigmentosa. The drug is administered as an injection under the retina (subretinal injection) following a parsplana vitrectomy. Luxturna is not yet available in India.
Stem Cell Therapy
Cell or stem cell replacement therapy is another form of treatment that is being tried. Initially, Embryonic stem cells (ESC) from fetal cells were used in research. In 2008, Prof Yamanaka from Japan showed that peripheral tissue from an adult (either skin or venous blood sample) can be used to reprogram the cells into induced pluripotent stem cells (iPSC) which can then be converted into various stem cells, including cells of the retina.
Since these do not change the genes, and instead deliver cells that possibly will form synaptic connections with the other cells in the retina, these do not have to be specific to each mutation. There are a few clinical trials trying to replace the damaged retinal cells with stem cells (www.clinicaltrials.gov)
Eyestem, a stem- cell organization housed within CCAMP, Bangalore, works towards developing scalable cell replacement therapies for AMD and inherited retinal diseases. Read more at www.eyestem.com