Ectopia lentis: a displaced lens in the eye and its link with Marfan syndrome

The lens sits behind the iris and the pupil and focuses light onto the retina. The NHS describes it as the transparent structure behind the pupil that focuses light. The Marfan Trust explains that the lens is normally held in position by thread-like fibres called zonules, and that these can be dysfunctional in Marfan syndrome, allowing the lens to become displaced.

When the lens moves, vision can change. The Marfan Trust describes two degrees of displacement. A subluxed lens is partially displaced but still in the pupillary area. A luxated or dislocated lens is completely displaced from its normal position. The degree of displacement guides what treatment is suitable.

The sources reviewed for this guide focus on the link with Marfan syndrome, which is the best-documented context in UK patient information. Lens displacement can have other causes, and the eye specialist will consider the cause in each individual rather than assuming one explanation.

The Marfan Trust lists the possible symptoms as short-sightedness (myopia), blurred vision, and increased pressure in the eye (glaucoma). The NHS lists myopia, glaucoma, cataracts and retinal detachment as other eye-related problems that can occur in Marfan syndrome, and explains that many people with Marfan syndrome have some type of vision problem.

Any sudden change in vision needs prompt assessment. The NHS eye injuries page says to go to A&E or call 999 if there are any changes to your sight after an eye injury, and the NHS uveitis page says the same if you cannot see. For eye pain, sensitivity to light or vision changes without an injury, the NHS advises an urgent GP appointment or NHS 111.

The NHS describes Marfan syndrome as a disorder of the body's connective tissues that children usually inherit from one of their parents. Typical characteristics include being tall, long slender limbs, heart defects and lens dislocation. The NHS says that in around 3 in 4 cases it is inherited from one parent, and in the rest the gene changes for the first time in the parent's egg or sperm. It says Marfan syndrome affects about 1 in 5,000 people in the UK.

The NHS diagnostic criteria for Marfan syndrome list dislocation of the lens of the eye as one of the major criteria, alongside an enlarged or torn aorta, a family history and a number of skeletal problems. That is why the Marfan Trust states that ectopia lentis is an important sign and why a geneticist is involved after an ophthalmologist finds it.

Because the heart and aorta can also be affected in Marfan syndrome, the NHS says a person with the diagnosis is looked after by a team that includes a geneticist, a cardiologist, an ophthalmologist and others. Finding ectopia lentis therefore often leads to heart checks as well as eye care.

The Marfan Trust says the eye examination by an ophthalmologist includes a test of vision and a slit lamp examination, which looks at the structures inside the eye. The NHS says an eye examination by an ophthalmologist to check for dislocation of the lens is one of the tests used when Marfan syndrome is being investigated, alongside an echocardiogram and, when needed, an MRI scan.

The NHS notes that, once Marfan syndrome has been diagnosed, a person may need an annual eye check-up to help identify new developments, because eye problems associated with the condition are potentially serious and may lead to permanent loss of vision.

The Marfan Trust says treatment depends on how far the lens has moved and could include glasses or contact lenses, or surgery to remove and replace the dislocated lens with an artificial lens implant. The NHS similarly says that if you are short-sighted your vision can usually be corrected with glasses or contact lenses, and that in rare cases where vision is significantly affected the lens may need to be replaced with an artificial one.

The NHS also explains the wider eye care: if cataracts develop you may need surgery to replace the clouded lens with an artificial lens, usually as keyhole surgery under local anaesthetic, and glaucoma, which has a higher risk in Marfan syndrome, is monitored carefully because vision loss from it cannot be cured, though it can usually be prevented from getting worse with eyedrops, laser treatment or surgery.

The NHS says vision problems can affect driving ability and points people to GOV.UK advice on driving with a health condition or disability. It also mentions that a young person may find the teenage years, when symptoms tend to be most apparent, difficult, and that a GP can help put people in touch with the Marfan Trust or counselling.

Because several specialists may be involved, it helps to keep a note of who is responsible for each part of care and to attend the recommended annual eye checks.