Author: Claude, from an owner-approved source list · Reviewed by: Dr Mina Abdelmseih · Reviewed: 2026-11-15 · Review due: 2027-11-15

Educational content only. Not personalised medical advice. Clinical decisions remain the responsibility of the treating clinician.

Retinal Gene Therapy, CRISPR and Mutation-Agnostic Treatments

Inherited retinal diseases (IRDs) are caused by variants in more than 280 genes [S12]. Gene replacement works for one of them, biallelic RPE65 disease, with voretigene neparvovec [S1] [S12]. Gene editing (CRISPR), RNA therapies (antisense oligonucleotides) and mutation-agnostic approaches such as neuroprotection and optogenetics are in trials [S8] [S9] [S12] [S13].

Resource tiers: this is a specialist research topic outside the Tier A / Tier B / Tier C low-resource focus of this library, so no resource tiers are defined here.

Red flags

• No genetic diagnosis, no gene-specific therapy. Voretigene neparvovec trial entry required confirmed biallelic RPE65 mutations [S1].
• Many phase 3 trials have missed their primary endpoints. The choroideremia phase 3 trial [S7] and the XIRIUS X-linked RP trial [S6] did not meet their primary endpoints.
• Surgery carries risk. Across AAV gene therapy studies, the cumulative incidence of at least one serious adverse event was 8%, often linked to the surgical procedure [S4].
• Antisense treatment can cause cataract. In the sepofarsen trial, 8 of 11 patients developed cataract [S9].

Recognise it

Of 101 IRD gene therapy trials registered up to the end of 2022, phase 1/2 was the most common phase (46 trials), and one led to an FDA-approved treatment [S5].

Confirm it

• A molecular (genetic) diagnosis is required for gene-specific therapy [S1] [S8].
• Enough viable retina: required for voretigene neparvovec [S1]; more preserved retinal area may improve choroideremia trial outcomes [S7].

Manage it

Before acting on this section, check the national and local guidelines, product information and regulatory approvals that apply where you practise. See the medical disclaimer.

Specialist management (IRD centres and trials)

1. Voretigene neparvovec (RPE65). In the phase 3 RCT (2017), 31 people were randomised to bilateral subretinal injection or control [S1]. Gains in functional vision and light sensitivity were maintained at 3 to 4 years, while visual acuity changed little [S2]. A meta-analysis (2021) of RPE65 studies found significant improvement in full-field light sensitivity and only modest changes in acuity [S3].
2. Other gene augmentation. XIRIUS (2024, RPGR) missed its primary microperimetry endpoint; the low dose improved some secondary outcomes [S6]. The choroideremia phase 3 trial (2023) did not meet its primary acuity endpoint [S7].
3. CRISPR gene editing. EDIT-101 (2024) was given to 14 participants; there were no treatment-related serious adverse events, and 6 had a meaningful improvement in cone-mediated vision [S8]. Delivery of larger editing systems is a key challenge [S11].
4. Antisense oligonucleotides. Sepofarsen (2022) showed post hoc improvements in acuity and retinal sensitivity; the lower dose had the better benefit-risk profile [S9]. ASO challenges include off-target effects, delivery and long-term safety [S10].
5. Mutation-agnostic approaches. Neuroprotection and complement modulation target shared disease mechanisms [S12]. Optogenetics is for late-stage disease after photoreceptor loss; see the optogenetics article [S13].

Refer when

Pitfalls

• Promising treatment before genetic testing [S1].
• Equating light-sensitivity gains with better acuity [S2] [S3].
• Assuming a phase 1/2 signal will hold in phase 3 [S6] [S7].
• Underestimating surgical risk [S4].

Evidence notes

• Only one randomised trial supports the approved therapy, and it was open-label [S1] [S3].
• Not covered by these sources: base and prime editing in humans, trial results after 2024, and approval status by country.

Related articles

• Optogenetics and Vision Restoration
• Leber Hereditary Optic Neuropathy

References

See the numbered source list below. Each marker [S#] links to its PubMed and DOI record.