Symptoms of RP most commonly appear during early childhood days. However, signs of severe vision impairment do not show up before adulthood. Signs and symptoms of RP include the following:

• Difficulty in seeing in low light or during night time.
• Longer duration and difficulty in adapting from light to dark.
• Development of tunnel vision that occurs due to loss of peripheral vision.
• In advanced cases, there is loss of central vision.
• No pain is associated with vision loss [7].
• Individuals with RP also suffer from extreme tiredness, cannot tolerate glare and cannot appropriately separate colors.

The following methods are used for diagnosing retinitis pigmentosa:

• Opthalmoscopy, which is a method meant for examining the retina after the pupils are dilated.
• Electroretinogram is done to determine the electrical activity of the retina [8].
• Fluorescein angiography method is carried out to analyze the blood flow to the retina and choroid.
• Tonometry test is required to measure the intraocular pressure inside the eyes.
• Refraction test is done to determine the prescription for eyeglasses.
• Slit–lamp examination, is done to examine the structures that are located in the front of the eye.

In addition to these tests, other diagnostic procedures such as visual acuity tests, color vision, pupil reflex response and visual filed test are also indicated for appropriate diagnosis of retinitis pigmentosa [9].

• No treatment can cure retinitis pigmnetosa. However, methods can be employed to slower the progression of degeneration in order to preserve the vision for longer periods. 
• Individuals with RP are advised to wear sunglasses so that further damage to the eyes, through ultraviolet rays can be prevented. Administration of vitamin A has been proven to be helpful in many cases as it is known to slow down the disease progression. However, several studies have also reported the risks associated with high doses of vitamin A on liver. Therefore, supplementation of vitamin A should be done with caution [10].
• Use of sources rich in omega 3 fatty acids has also been found to be useful in treatment of RP. Adminstration of lutein and zeanxanthin in doses of 20 mg/day is indicated in patients with RP. These are macular pigments known prevent the macula from oxidative damage.
• In more advanced cases, cataract surgery has been found to improve vision in majority of the cases [11]. Of lately, retinal implants for treating RP have been approved by FDA. This method is indicated in patients aged 25 years and above, who are in the advanced stage of the disease [12]. Such a kind of method, would however not help in vision restoration, but would certainly improve the individual’s ability to see images and perceive movements.

Loss of vision is a gradual process in individuals with retinitis pigmentosa. With treatment, the process of degeneration can be slowed down to a significant extent, in order to preserve vision for longer duration [6].

Heredity is the major factor for development of retinitis pigmentosa. Individuals with a family history of this degenerative eye disorder are at an increased risk of developing the same. It has been found that, about 70% of cases of RP are hereditary in nature. Mutations of several genes account for 25% cases of autosomal forms of RP [2].

In the US, cases of RP are reported in about 1 in 4000 individuals. Globally the incidence of RP is estimated to be about 1 in 5000. In Switzerland, incidence of RP is low with prevalence rate of 1 in 7000 individuals [3].

Males are at an increased risk of developing RP compared to females. The condition is usually diagnosed during young adulthood; however signs and symptoms can be evident from infancy onwards.

In the condition of retinitis pigmentosa, genetic mutations give rise dystrophy of the rods and cons of the retinal cells. Current research findings have reported histologic changes along with genetic mutations [4]. The major pathway for development of RP is the death of photoreceptor cells that occurs due to apoptosis. The progressive vision loss results to series of events that primarily begin through shortening of the outer segments of the rods. This event is followed by loss of rod photoreceptor. This sequence of events is finally followed by death of rod photoreceptors which ultimately leads to vision loss [5].

So far, there are no strategies to prevent the development of retinitis pigmentosa. However, genetic counseling and associated testing can help in determination whether individuals are at risk of developing the disease.

Gradual and progressive loss of light sensitive cells of the eyes is the classical feature of the disease. Individuals affected by retinitis pigmentosa (RP), also suffer from night blindness and tunnel vision, which occurs due to degeneration of peripheral visual field. It is a progressive disease of the eye, which does not have any cure. Retinal implants have been approved by FDA for individuals aged 25 years and above [1].

• Definition: Retinitis pigmentosa (RP) is a degenerative form of eye disease which causes gradual loss of vision due to damage to the retina. In many cases, signs of the disease may begin to appear from infancy, while in some cases, signs are evident in late adulthood.
• Cause: Genetic mutations are the major factor behind development of RP. Individuals with family history of the disease are at an increased risk of contracting this condition.
• Symptoms: Symptoms of retinitis pigmentosa include vision problems during night time or poor light conditions, difficulty in driving in foggy weather, development of tunnel vision and central vision loss occurs in advanced stages of the disease.
• Diagnosis: The condition can be diagnosed with ophthalmoscopy, electroretinogram, refraction test, visual acuity test, slit–lamp test, fluorescein angiography and tests to measure the color vision and intraocular pressure of the eyes.
• Treatment: Affected individuals are advised to wear sun glasses to protect their eye from UV rays of sun. Administration of vitamin A and omega-3 fatty acids has also shown positive effects on controlling vision degeneration. Retinal implants and cataract surgery are carried out in most advanced cases and have proved to be beneficial for patients with RP.

1. Chuang AT, Margo CE, Greenberg PB. Retinal implants: a systematic review. Br J Ophthalmol 2014; 98:852.
2. Hebrard M, Manes G, Bocquet B, et al. Combining gene mapping and phenotype assessment for fast mutation finding in non-consanguineous autosomal recessive retinitis pigmentosa families. Eur J Hum Genet. Dec 2011;19(12):1256-63.
3. Grover S, Fishman GA, Anderson RJ, et al. Visual acuity impairment in patients with retinitis pigmentosa at age 45 years or older. Ophthalmology. Sep 1999;106(9):1780-5.
4. Berson EL, Rosner B, Simonoff E. Risk factors for genetic typing and detection in retinitis pigmentosa. Am J Ophthalmol 1980; 89:763.
5. Grover S, Fishman GA, Brown J Jr. Patterns of visual field progression in patients with retinitis pigmentosa. Ophthalmology 1998; 105:1069.
6. Berson EL. Long-term visual prognoses in patients with retinitis pigmentosa: the Ludwig von Sallmann lecture. Exp Eye Res 2007; 85:7.
7. Denman S, Weleber R, Hanifin JM, Cunningham W, Phipps R. Abnormal night vision and altered dark adaptometry in patients treated with isotretinoin for acne. J Am Acad Dermatol. Apr 1986;14(4):692-3.
8. Bjork A, Karpe G. The electroretinogram in retinitis pigmentosa. Acta Ophthalmol Scand 1951; 29:361.
9. Sandberg MA, Brockhurst RJ, Gaudio AR, Berson EL. The association between visual acuity and central retinal thickness in retinitis pigmentosa. Invest Ophthalmol Vis Sci 2005; 46:3349.
10. Berson EL, Rosner B, Sandberg MA, et al. A randomized trial of vitamin A and vitamin E supplementation for retinitis pigmentosa. Arch Ophthalmol 1993; 111:761.
11. Bastek JV, Heckenlively JR, Straatsma BR. Cataract surgery in retinitis pigmentosa patients.Ophthalmology. Aug 1982;89(8):880-4. 
12. US Food and Drug Administration. FDA approves first retinal implant for adults with rare genetic eye disease [news release].