Two images of a pair of eyes illustrating the Strabismus frequently associated with the visual impairment of HPS, Hermansky-Pudlak Syndrome, and Albinism.

Strabismus


Strabismus can have both visual and cosmetic affects.  The eyes do not work together effectively when focusing (or ‘fixing’) on an object, particularly if it is moving (' tracking an object’).  One or both eyes may appear to close to the nose as if pointing toward one another (Esotropic strabismus) or appear to be looking in different directions (Exotropic).


Ophthalmologists prefer to treat infants starting at around six months of age, before the function of their eyes has fully developed.  They may recommend that parents patch one eye to promote the use of the non-preferred eye.



For cosmetic reasons some people choose to have this corrected through surgery.  This involves the shortening of some of the muscles that control eye movement.  This does not always fully correct the problem .  Neither is it clear that it improves vision or that it allows both eyes to fix on the same point.


Since Hermansky-Pudlak syndrome involves a platelet bleeding disorder, it is imperative that the ophthalmologist is made aware of this. ·There are safety measures and concerns that need to be addressed before surgery should be considered.


With both Hermansky-Pudlak Syndrome and other types of albinism the nervous system - or optic pathways - of the eyes differ from normal.  Too many nerve fibres from each eye cross over, or decussate. Click here for a diagram to illustrate this. It is believed that the excessive decussation of the optic nerves is caused by a lack of melanin pigment as a foetus develops in the womb.    This prevents both eyes from working together to give binocular vision.  A person may have both eyes open but only be ‘seeing’ with one eye at a given moment.  This can result in poor depth perception and 3D vision.  The practical affects of this usually include difficulty in judging the depth of stairs and changes in surface level, judging the speed of moving objects (ball games, road traffic, etc) and aiming at a target.

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Two images of a pair of eyes illustrating the Strabismus frequently associated with the visual impairment of HPS, Hermansky-Pudlak Syndrome, and Albinism.

Features of the Visual impairment of Hermansky-Pudlak Syndrome