A Fast-Moving Inherited Macular Dystrophy
Picture a coastal sea wall that gradually thickens where it shouldn't, growing brittle and uneven rather than staying smooth and strong. Behind the retina sits a comparable structure, Bruch's membrane, and in Sorsby fundus dystrophy a faulty protein causes it to thicken abnormally in just this way. The retina responds the way a struggling town might respond to a failing sea wall — by hastily punching through emergency channels, in this case new blood vessels, that are poorly built from the start and prone to leaking almost as soon as they form. This abnormal vessel growth, arriving decades earlier than it typically would in ordinary age-related disease, is what makes Sorsby dystrophy one of the more aggressive conditions covered on this site.
For a Somali patient in their thirties or forties whose central vision drops sharply over a matter of weeks rather than years, that speed itself is often the earliest clue pointing toward Sorsby rather than a slower, more typical dystrophy.
What makes Sorsby dystrophy stand out is speed — central vision in one eye can genuinely collapse within weeks, with the other eye typically catching up within a handful of years. Patients often describe straight lines suddenly bending or a blurred patch spreading fast in the middle of their sight, and some notice a strange difficulty with dim light creeping in months ahead of that, almost as an early warning most people don't recognise until later.
A faulty TIMP3 gene is behind essentially every confirmed case, and its normal job is keeping the turnover of tissue around Bruch's membrane in check. Once that job isn't done properly, the membrane grows unnaturally thick, and the retina answers by forcing a network of new vessels through the weakened barrier — vessels that are poorly formed from the outset and start leaking almost as soon as they exist. It takes just one faulty copy, from either side of the family, to bring the condition on.
A telltale scattering of pale, yellow-white spots along the retinal vessels is often the first thing to catch an examiner's eye during a routine look at the fundus. Once that's spotted, the focus shifts to hunting down active new vessels specifically, using OCT angiography or, where a sharper picture is needed, fluorescein angiography, since knowing whether those vessels are actively leaking changes how urgently we act. A TIMP3 genetic test confirms what's driving things, and because this particular condition doesn't wait around, we don't let that test sit in a queue.
Whenever we find vessels that are actively leaking, sorting that out comes before anything else on the plan. Once things have calmed down and the eye is stable, eligible patients move on to regenerative stem cell therapy aimed at supporting the retina from there, and because Sorsby has a reputation for moving quickly, we check back with these patients more often than we would with a slower-moving dystrophy.
It genuinely can, and that speed is actually part of what tells us we might be looking at Sorsby dystrophy rather than something else. Most inherited macular conditions move over years, not weeks, which makes this pace unusual and worth acting on quickly.
It's an easy mix-up to make once new blood vessels are involved, since the two can look quite alike on a scan. What separates them comes down to how early it started, whether it runs in the family, and a TIMP3 genetic test.
It's worth treating as a priority, since vessels that are actively leaking can cause further loss quite quickly if left alone. Getting that specific problem settled is always our first move before anything else.
Not guaranteed, but the odds are meaningful, since this follows a dominant inheritance pattern — each child of an affected parent carries roughly a fifty-fifty chance of inheriting the gene. How badly it shows up varies from person to person, and testing can give your family more clarity.