HORIZON: A Phase II Study to Evaluate the Safety and Efficacy of Two Doses of GT005

Inclusion Criteria:

   1. Able and willing to give written informed consent

   2. Age ≥55 years

   3. a. In Stage 1: Have a clinical diagnosis of GA secondary to AMD in the study eye, as
   determined by the Investigator, and a diagnosis of AMD in the contralateral eye; b. In
   Stage 2: Have a clinical diagnosis of GA secondary to AMD in the study eye, as
   determined by the Investigator, that is non-foveal, as determined by the central
   reading centre, or has a CFI rare variant genotype and meets inclusion criteria 3a,
   and a diagnosis of AMD in the contralateral eye (except if monocular)

   4. GA lesion(s) within an acceptable size on FAF, in the study eye

   5. The GA lesion in the study eye must reside completely within the FAF image

   6. Up to 25% of the enrolled study population are permitted to have CNV in the fellow eye

   7. Have a BCVA of ≥24 letters (6/95 or 20/320 Snellen acuity equivalent), using ETDRS
   charts, in the study eye

   8. a. In Stage 1: Meet one of the pre-specified AMD genetic subgroup criteria; b. In
   Stage 2: Genotyping is not required for study eligibility

   9. Able to attend all study visits and complete the study procedures

10. Women of child-bearing potential must have a negative pregnancy test within 2 weeks
   prior to randomisation (not required for postmenopausal women) or provide
   documentation of being surgically sterilised

Exclusion Criteria:

   1. a. In Stage 1: Carriers of excluded genetic variants; b. In Stage 2: Subjects are
   excluded if they have a clinical diagnosis of Stargardt Disease or other retinal
   dystrophies

   2. Have a history, or evidence, of CNV in the study eye

   3. Presence of moderate/severe or worse non-proliferative, diabetic retinopathy in the
   study eye

   4. Have history of vitrectomy, sub-macular surgery, or macular photocoagulation in the
   study eye

   5. History of intraocular surgery in the study eye within 12 weeks prior to Visit 1

   6. Have clinically significant cataract that may require surgery during the study period
   in the study eye

   7. Presence of moderate to severe glaucomatous optic neuropathy, uncontrolled intraocular
   pressure (IOP), despite use of two or more topical agents; or a history of
   glaucoma-filtering or valve surgery

   8. Axial myopia of greater than -8 diopters in the study eye

   9. Have received any investigational product for the treatment of GA within the past 6
   months or 5 half-lives (whichever is longer), other than nutritional supplements such
   as the age-related eye disease study (AREDS) formula

10. Have received a gene or cell therapy at any time.

11. Have a contraindication to the protocol specified corticosteroid regimen

12. Are unwilling to use two forms of contraception (one of which being a barrier method)
   for 90 days post-dosing, if relevant

13. Active malignancy within the past 12 months, except for appropriately treated
   carcinoma in situ of the cervix, non-melanoma skin carcinoma, or prostate cancer with
   a stable prostate-specific antigen (PSA) ≥ 12 months

14. Have any other significant ocular or non-ocular medical or psychiatric condition
   which, in the opinion of the Investigator, may either put the subject at risk or may
   influence the results of the study