Do you know that your retina contains the highest concentration of Omega-3 DHA in your body? DHA plays an important role in retinal signalling mechanisms.

Question:
Why is DHA so important in the retina?

Answer:
DHA is a critical part of retinal structure. Its presence enhances the development of photoreceptors, specialized cells in the retina necessary for vision. High DHA concentrations are needed for rhodopsin-a pigment in the photoreceptor rod cells-to respond to light in a way that permits vision in dim light and at night. The highly unsaturated nature of DHA has unique effects on retinal cell membranes allowing them to transmit light signals very quickly.

Achieving Optimal Eye Function :
Beyond development, the eyes and the brain need plentiful stores of DHA to function optimally. Cells in the retina, brain and other parts of the nervous system have connecting arms that transport electrical currents, sending visual information from the retina to the brain and messages from the brain throughout the body. DHA supplementation ensures the optimal composition of cell membranes necessary for the most effective transmission of these signals. DHA is correlated with improved visual and mental function.

In young infants and children :
The development of both the retina and visual cortex are dependent on DHA. The retina develops rapidly during the final months of pregnancy and the first six months of infancy. Studies found that the eyesight of full term babies fed DHA enriched formula was measurably more acute than that of babies fed formula without DHA.

DHA affects the eye's ability to distinguish fine spatial detail such as closely spaced lines, known as visual resolution acuity. Children's vision continues to develop throughout their preschool years and eye/hand/body coordination, eye teaming, depth perception continues. Infants who do not obtain enough DHA during fetal development (pregnancy) have sub-optimal visual acuity and less DHA in their retinas. These differences are especially notable in infants born preterm. In term infants, differences in visual acuity are less consistent, in part because term infants have some DHA in their body fat.

In aging :
In aging, visual function usually declines owing to changes in retina and other eye cells. Cell membranes lose some of their fluidity, cell structure changes, deposits accumulate, oxidation causes damage and cells are lost. These changes contribute to impaired vision in later life.

In age-related macular degeneration (AMD), yellowish deposits (drusen) accumulate in the macula, the central region of the retina .Cells in the macula break down and vision becomes distorted and blurry. Vision loss may develop. Drusen may develop into advanced forms of AMD, threatening the ability to see. As the most common or dry type of AMD progresses, the macular cells break down. Finally, the macular cells break down and central vision becomes severely impaired.

Second type of AMD, known as wet or neovascular AMD, is responsible for 90% of the vision loss in this condition. In wet AMD, the blood vessels behind the eye become abnormal and fragile, risking leakage and hemorrhage. Advanced AMD may affect one or both eyes and either wet or dry type can lead to blindness.

More recently, fish consumption twice a week or more was linked to significantly lower risk of AMD in a study of twins. Smoking increased the risk nearly 2-fold. Interestingly, in patients with advanced AMD, higher omega-3 PUFA consumption was associated with lower risk of the condition, but only when omega-6 or vegetable PUFA consumption was low. People with higher vegetable fat or linoleic acid (an omega-6 PUFA) intakes were more likely to develop AMD.

Studies suggest that the type of fat we consume can reduce or increase the chance of developing AMD. High intakes of polyunsaturated vegetable oils may increase the chance of developing the condition and undermine the effects of fish oil omega-3s. Boosting fish and fish oil consumption may lower the chance of developing AMD and slow its progress once it has started. Whether omega-3s can prevent the condition we do not know.