People are always amazed at how much Kai looks at them eventhough he is ‘legally blind’. I get asked all the time what I think he CAN see, and while i don’t really know the answer I though it may help to share a few facts about blindess and Kai’s vision.

What does it really mean to be legally blind?

According to the American Foundation for the Blind:

http://www.afb.org/default.aspx

Legal blindness is a level of vision loss that has been legally defined to determine eligibility for benefits. The clinical diagnosis refers to a central visual acuity of 20/200 or less in the better eye with the best possible correction, and/or a visual field of 20 degrees or less. Often, people who are diagnosed with legal blindness still have some useable vision.

Kai’s last vision report states that his binocular visual acuity was 20/270. His right eye alone also tested 20/270 and his left eye tested 20/540.

What is visual acuity? 

Visual acuity is the clinical measure of the eye’s ability to distinguish details of the smallest identifiable letter or symbol. This measurement is usually given in a fraction and is based upon visible print size. Typical vision is 20/20. If an individual sees 20/200, the smallest letter that this individual can see at 20 feet could be seen by someone with typical vision at 200 feet.

Visual Field Loss:

http://www.ssc.education.ed.ac.uk/resources/vi&multi/eyeconds/OpChGl.html

The visual field is the medical word for the full area of a child’s visual world (what they see). Visual Field Loss may occur if damage occurs to a part of the visual pathway. The visual pathway that signals travel along includes the eye, optic nerve, optic chiasm and the special ‘vision’ parts of the brain. Damage to the visual pathway may cause blurring or even complete loss of bits of the visual world (visual field).

If damage occurs to the optic chiasm then a special type of visual field loss may occur. The child will lose the outside bits of the visual world on both sides. It is called a Bi-temporal Hemianopia. ‘Bi’ means both right and left sides. ‘Temporal’ means the outside bit of vision. ‘Hemi’ means half and ‘anopia’ means no vision.

It usually takes younger children longer to notice visual field loss. Older children may notice that something is wrong with their vision sooner. The visual field loss does not usually get better and may slowly get worse.

Kai’s visual field is pretty limited at this point.  Most of his vision is in the lower left part of his left eye.  The last visual field screen he had at Perkins showed he doesn’t have much, if any,  visual field in the right eye. He does have bi-temporal hemianopia.

The last part of Kai’s visual diagnosis is Nystagmus.  Kai has intermitten horizontal nystagmus.  It is usually worse after chemo or when he is tired.  Most people dont even notice it most of time time

Nystagmus:

http://www.aoa.org/x9763.xml

Nystagmus is a vision condition in which the eyes make repetitive, uncontrolled movements, often resulting in reduced vision. These involuntary eye movements can occur from side to side, up and down, or in a circular pattern. As a result, both eyes are unable to hold steady on objects being viewed. Nystagmus may be accompanied by unusual head positions and head nodding in an attempt to compensate for the condition.

Persons with nystagmus may experience reduced visual acuity. They may also have problems with depth perception that can affect their balance and coordination. Nystagmus can be aggravated by fatigue and stress.

Most individuals with nystagmus can reduce the severity of their uncontrolled eye movements and improve vision by positioning their eyes to look to one side. This is called the “null point” where the least amount of nystagmus is evident. To accomplish this they may need to adopt a specific head posture to make the best use of their vision.

So YES Kai can see you! He can also hear you smell you ans sense you. He has gotten good at adapting his vision, it is all he knows. He loves to see the fast dark movement when his dog runs.  He loves to hear the funny sounds his dog makes.  He likes when you are close, but not too close, becuase then he can only see a little bit of you.  He tilts his head and his eyes often gaze to one side in order to better see you.

He enjoys sounds and movement, but these can also be a bit confusing when you can’t see.  He sometimes startles easily at an unexpected sound.

So for Kai is is nice to let him know when you are aproching, or when youv walked in the door, or are going to pick him up, or anything else that maybe unexpected if you couldn’t see.  Touch and sounds cues are somthing we learned are very important ways to help Kai learn about the world around him.  Giving him a consistant warning/cue helps him learn anticipation, safety and decision making.

 To learn more about teaching and interacting with a child with visual impairment:

http://www.tsbvi.edu/infants/3293-the-impact-of-visual-impairment-on-develop