A cone dystrophy is an inherited ocular disorder characterized by the loss of cone cells, the photoreceptors responsible for both central and color vision. Presentation
The most common symptoms of cone dystrophy are vision loss (age of onset ranging from the late teens to the sixties), sensitivity to bright lights, and poor color vision. Therefore, patients see better at dusk. Visual acuity usually deteriorates gradually, but it can deteriorate rapidly to 20/200; later, in more severe cases, it drops to "counting fingers" vision. Color vision testing using color test plates (HRR series) reveals many errors on both red-green and blue-yellow plates. Dystrophy of the rods and cones
Dystrophy of the light-sensing cells of the eye may also occur in the rods as well, or in both the cones and the rods. A type of rod-cone dystrophy—where rod function decline is typically earlier or more pronounced than cone dystrophy—has been identified as a relatively common characteristic of Bardet–Biedl Syndrome.At least one type of autosomal dominant cone-rod dystrophy is caused by mutations in the guanylate cyclase 2D (not geometrical) gene (GUCY2D) on chromosome 17. Mechanism
The pathogenesis of cone dystrophy has yet to be elucidated. It appears that the dystrophy is primary, since subjective and objective abnormalities of cone function are found before ophthalmoscopic changes can be seen. However, the retinal pigment epithelium (RPE) rapidly becomes involved, leading to a retinal dystrophy primarily involving the macula.
The beta-carotenoids, lutein and zeaxanthin, have been evidenced to reduce the risk of developing age-related macular degeneration (AMD), and may therefore provide similar benefits to people with cone dystrophy.Consuming omega-3 fatty acids (docosahexaenoic acid and eicosapentaenoic acid) has been correlated with a reduced progression of early AMD, and in conjunction with low glycemic index foods, with reduced progression of advanced AMD, and may therefore delay the progression of cone dystrophy. Dr. Randall Walker, who has a variation of the condition himself, invented a software to enable low vision people to read with greater ease.<ref>url= https://www.bizjournals.com/twincities/print-edition/2014/06/06/made-at-mayo-mayo-professor-doubles-as-founder-of.html <ref>

Notes
References
Stephen J. Ryan et al., Retina, 3rd ed. (C.V. Mosby, 2001) ISBN 0-323-00804-6
Stephen J. Ryan et al., Retina, 4th ed. (C.V. Mosby, 2005) ISBN 0-323-02598-6
Carpentier S, Knaus M, Suh M (April 2009). "Associations between lutein, zeaxanthin, and age-related macular degeneration: an overview". Crit Rev Food Sci Nutr. 49 (4): 313–26. doi:10.1080/10408390802066979. PMID 19234943. S2CID 23524407. {{cite journal}}:  CS1 maint: multiple names: authors list (link) "Abstract doesnt include conclusion"
Chiu CJ, Klein R, Milton RC, Gensler G, Taylor A (September 2009). "Does eating particular diets alter the risk of age-related macular degeneration in users of the Age-Related Eye Disease Study supplements?". Br J Ophthalmol. 93 (9): 1241–6. doi:10.1136/bjo.2008.143412. PMC 3033729. PMID 19508997. {{cite journal}}:  CS1 maint: multiple names: authors list (link) "Conclusions: The findings show an association of consuming a diet rich in DHA with a lower progression of early AMD.