OCULAR MANIFESTATIONS
The FBN 1 gene produces microfibrils that support the lens and keep it
in position, the microfibrils are also found in the iris, Schlemm canal
and cornea. The defect in these microfibrils is associated with ectopia
lentis (lens subluxation), the development of miosis, wider corneal
diameter, and pupillary hypoplasia 9-11
Myopia is the commonest ocular manifestation of the disease, being
associated with elongation of the globe with 60% of these having
concomitant lens dislocation 12, 13. The incidence of
ectopia lentis in Marfan syndrome varies from 30% to 72% in different
studies it may however be first seen in the second decade of life14-16.
Less common ocular manifestations are early cataracts, retinal
detachment, and glaucoma. Ocular abnormalities such as myopia,
astigmatism, anisometropia, ectopia lentis, and retinal pathologies may
result in amblyopia. The earlier the onset and the longer it goes
untreated, the harder amblyopia is to correct 17.
Therefore, patients with MFS should be screened annually and examined
for refractive errors and other ocular pathologies. Eyeglasses are the
first step to correct blurred vision caused by subluxated lenses18. Removal of a dislocated lens and the possible
insertion of an artificial one may be considered but not usually
required 14.
The indications for surgery in lens dislocation are inability to achieve
good corrected visual acuity, risk of amblyopia in children, posterior
dislocation of the lens into the vitreous cavity, anterior dislocation
of the lens with or without secondary glaucoma, impending to complete
lens dislocation, lens induced glaucoma or uveitis, and cataract19.
Glaucoma may develop at a later age and may be as a result of phacolytic
glaucoma from dislocation of a matured lens 20, 21.