Oxnard - Port Hueneme Optometry Dr. Don Steensma 465 W. Channel Islands Blvd, Port Hueneme, CA 93041 805/486-3585
Our eye color is determined by how many melanocyte pigment cells are present on our iris. If we have many our eyes appear brown. If their are fewer pigment cells the irises may appear blue, green or grey. Hazel eyes are an indeterminate color - maybe dark in some areas and light in other areas.
Our babies eyes may change color. Many baby's irises are gray at birth, and they may stay that color or they may darken over the first six to nine months of life. So gray or blue eyes can turn brown, green, or hazel, but brown eyes won't lighten and become blue.
The gene for blue eyes is recessive, meaning it does not produce a blue eye unless it's matching gene from the other parent is also for blue eyes. So even if both parents have brown eyes, they may both have a recessive blue gene and have a 25% chance of having a baby with blue eyes. If both parents have blue eyes their is a 0% chance of having a blue eyed baby.
It's thought that blue eyes arose in a solitary genetic mutation partially towards albinism. The fully albino eye has no iris pigment cells and appears pink.
A babies eye at birth is 75% of their adult size. Their eyes appear large because the body is so small. During the first two years of life, the optic nerve, visual function and internal eye structures continue to develop. The newborn’s visual acuity (sharpness of vision) is approximately 20/400. This is equivalent to seeing only the big letter “E” on an eye chart. Newborns don't pay much attention to the visual world, but by 6-8 weeks of age they will follow an object. They will begin to enjoy seeing their mothers face.
Testing has proved that Vision slowly improves to 20/20 by age 2 years, but most kids will measure about 20/40 untill age 5-6. At 4 months they start to work as a team and develop binocular vision. Color vision is present at birth.
The most common problems with a babies eye are infections and excess tearing due to a blocked tear duct. The infection is treated with antibiotics. In most caes the blocked tear ducts open on their own, but sometimes they must be probed to open them. Some babies are born with cataracts and some have binocularity problems preventing the eyes from working together and ambylopia or "Lazy Eye".
Most first graders see pretty good but maybe 10% have vision problems. By grade 5-6 some kids are developing myopia and need glasses for distance tasks. That might bring the percentage of students with vision problems to 30%.
The extended time spent reading results in a greater percentage of kids developing myopia and needing glasses for distance visual tasks.
If the myopia doesn't get you, vision is fairly stable untill about age 42. When we focus on near tasks, the ciliary muscle within the eye pulls on the lens within our eye, changing the focus. In a young person the lens is very flexible and focusing is easy. As we age the lens becomes less flexible, and even though the ciliary muscle is as strong as ever most people start to have focusing difficulty by age 42. During the 40's and into the mid-50's, near vision progressively gets worse, but then stabilizes by age 55, because all the focusing ability is lost. There is no more to lose. Many people, especially women, develop Dry Eye Disease in this age group.
In the later 60's most people start developing cataracts. That lens that has been getting stiffer over the previous 20 years now is becoming cloudy. When the clouding gets bad enough to impact vision significantly, we call it a cataract. The eye doctors challenge is to try and keep the vision good enough. When it's impacting the persons lifestyle significantly cataract surgery is necessary. This is a pain free out-patient procedure that is very straight forward these days. Diabetics tend to get cataracts 10 years earler than most.
In the 60's the body often starts to lose a little metabolic control and things don't function as well as when we are younger. See the section about "Eye Disease" on this web site. Many diabetics develop diabetic retinopathy in the 60's. In the late 60's and into the 80's macular degeneration and glaucom becomes more prevalent.