An Observational Study of Natural Disease Progression in Participants With Macular Dystrophies Expressing a Stargardt-type Clinical Presentation
Macular dystrophies are a group of inherited eye conditions that affect the macula. The macula is in the center of the retina, the light sensitive part at the back of the eye. In people with macular dystrophies, some of the cells in the macula gradually stop working and may die over time. This leads to vision loss in the center of the eye. Side vision (peripheral vision) is mostly unaffected. Stargardt disease (STGD) is a type of macular dystrophy which is caused by 1 faulty gene (ABCA4). Vision loss most typically happens in childhood, but many people do not develop it until they are adults. As well as STGD, there are other macular dystrophies that look very similar to STGD but that are caused by many other different genes. Together, STGD and STGD-like conditions can be called STGD-type macular dystrophies. This is because they look the same clinically and have similar symptoms. Since different genes can cause these conditions, genetic testing is the only way to be sure which specific condition a person has. In this study, researchers want to learn if the disease progresses in a similar way in people with STGD and STGD-like macular dystrophies. People taking part in the study will continue to manage their condition, as agreed with their own doctor. People will visit their clinic every 6 months to have various standard eye tests and imaging. The information collected will include questions about people's wellbeing, general health, medication and supplements taken, and daily activities. Children over 6 years old and adults with STGD-type macular dystrophies may take part in this study. They will be in the study for up to 24 months (2 years). The study sponsor (Astellas) will not decide how people's condition is managed. However, the sponsor will provide instructions on when people visit their clinic and what is recorded during the study. If available, medical records, clinical and imaging data from previous visits going back 24 months will also be reviewed.
• Participant has a documented clinical diagnosis of macular dystrophy expressing a STGD-type clinical presentation and molecular confirmation, defined as either:
‣ ABCA4-associated disease: presence of biallelic (pathogenic or likely pathogenic) ABCA4 variants, or one definite disease-causing ABCA4 variant together with a typical phenotype consistent with STGD.
⁃ STGD-like macular dystrophy: presence of one or more pathogenic variants in a gene known to cause macular dystrophy, as appropriate for its expected inheritance mode. Note: All genetic testing should be performed by a Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory or equivalent whenever possible. Acceptable documentation includes a copy of the genetic test report, laboratory certification statement, or clinical notes explicitly referencing CLIA certification. Predicted pathogenic variant of uncertain significance (VUS) that cannot be confirmed by standard laboratory criteria as certainly disease-causing (novel mutations) will be considered on a case by-case basis.
• Participant has sufficiently clear ocular media and adequate pupillary dilation to allow for all imaging procedures.
• Participant has intraocular pressure (IOP) both at screening and baseline of ≤ 21 mmHg measured by applanation tonometry. Note: Participant who is on topical IOP lowering treatment may also be included.
• Participant has a spherical equivalent refractive error between + 8.00 D and - 10.00 D. Eyes with high myopia (\> -10.00 D) are permitted only if there are no signs of myopic degenerative macular changes.
• Participant has a BCVA ranging from 20/500 to 20/40 (equivalent to 15 to 70 ETDRS letters read at 1 meter)
‣ For participants in the \> 20/80 to ≤ 20/40 BCVA range (moderate visual impairment \[MVI\]): presence of a visible definite or probable residual EZ on SD-OCT (no minimum residue size required) and a minimum central mean subfield retinal thickness on optical coherence tomography (OCT) ≥ 150 µm
⁃ For participants in the ≥ 20/500 to ≤ 20/80 BCVA range (SVI): presence of a residual outer nuclear layer (ONL) within the macular OCT scan area and measurable within the Age-Related Eye Disease Study (AREDS) grading grid and no residual EZ or minimal thickness of the ONL required
• Participant has evidence of retinal pigment epithelium (RPE) disease/damage on SD-OCT (hypertransmission defects \[HTDs\]) and/or FAF imaging.
• Participant has evidence of at least questionably decreased autofluorescence (QDAF) (incomplete retinal pigment epithelial and outer retinal atrophy \[iRORA\]), defined as mottled or speckled hypo-autofluorescence (AF) signal, mixed with or without hyper- AF, on FAF imaging. Note: At study onset, having patches of definitely decreased autofluorescence (DDAF) within the FAF image and/or patches of complete retinal pigment epithelial and outer retinal atrophy (cRORA) on SD-OCT ≥ 250 µm will not be a requirement for participation but will be acceptable for inclusion, so long as:
‣ DDAF/cRORA areas are contained within the limits of the AREDS grading grid (≤ 12 disc areas), and physically distinct and separate from other areas of QDAF, DDAF and/or hyper-AF that may be present outside the AREDS grading grid, and
⁃ the other BCVA and SD-OCT required inclusion criteria are also met.
• Participant is able to comply with the protocol and willing to undertake all scheduled visits and assessments during the total study period.
• Participant is deemed capable of performing reliably all tests required for participation.