10 Rare Eye Diseases & Their Treatment

“The eye is the mirror of the soul.”

Besides showing the true nature of people, the eyes also reveal a lot of secrets about health. There are a few eye diseases that affect us in adverse ways. Some of these occur often and some may occur rarely.

So here is a list of 10 rare eye diseases and how they can be treated:

1. Choroideremia

   Choroideremia is caused due to the decay of the photoreceptor cells lining at the rear of the eye which helps in light-sensing. It is a genetic condition that intensifies loss of vision largely in males. The estimate of loss of vision may differ from person to person but it will eventually lead to complete blindness. The typical appearances at the rear of the eye and X-linked genetic pattern assist the doctors in detecting this rare eye disease.

   Otherwise, Choroideremia in all probability goes underdiagnosed because its symptoms are more or less like a handful of other retinal problems like retinitis pigmentosa. Choroideremia damages the choroid (a network of blood vessels) present at the back of the retina. The work of the choroids is to deliver nutrients and oxygen for the nourishment of the retinal pigment epithelial cells as well as the cone and rod cells which are photoreceptors. Due to insufficiency of nourishment from the choroid, the rod cells die leading to partial blindness during night. This progresses overtime resulting in narrowing of vision and finally complete blindness in the late adulthood.

   Treatment: For low vision, aids like magnifying glasses or telescopic lenses can be used. Researchers have found CHM gene as the causative agent of this disease. A complete cure has not been formulated however, a treatment has been materialized. In this, the patient’s retina is detached and a safe virus is injected to enhance vision. This has not had any side effects and has improved vision. Further effectiveness of this treatment is being monitored.

2. Retinitis Pigmentosa

   Rod cells help with night vision and cone cells with colour vision and reading. These cells can be found in the rear of the eye in the retina. Retinitis pigmentosa which is an inherited disease kills these cells gradually leading to blindness. Although Retinitis pigmentosa causes blindness, a lot of people retain their central vision till their middle age. Earliest symptoms of this rare eye disease are low visibility in dim light including when going from a well lit area to a dark place and vice versa. In some cases it can be noticed in children in some others it is not evident until adulthood is reached. The degree of progression and the rate of loss of vision also differ from person to person including diseased individuals of the same family. It affects both eyes equally and it is tough to foresee how it will affect the patient at a particular time.

   

   Treatment: For maximization of the existing vision, one can use magnifying or telescopic lenses. Other technologies are being discovered by the scientists that include the stem cell technology and retina implantation. Stem technology helps to replace the degenerated cells and dead retinal cells i.e. the rod and the cone cells. Replacement of retinal pigment epithelium cells will help in the better nourishment of the living retinal cells. Experimentation is going on which deals with replacement of the actually dead retinal cells with an electronic microchip that will bring vision to the living cells. The microchips electronically indicate the remaining cells which in turn pass the wave to the optic nerve for processing vision. These do not help in improving the complete visual capability but helps in distinguishing between lit and dark places.

3. Usher Syndrome

   Usher Syndrome causes both deafness and blindness (due to retinitis pigmentosa) in a patient. Deafness is the first symptom that can be observed in a child. This rare eye disease is mostly inherited. Usher syndrome can be broadly categorized into type 1, type 2 and type 3.

   Type 1: Deafness affects from the very birth and is so acute that hearing aids do not help. Signs of retinitis pigmentosa are also evident. Along with deafness and blindness, the child also fails to evolve intelligible pronunciation.

   Type 2: Deafness also affects the patient at an early age but is less severe than type 1 and therefore the hearing aids work in providing audibility. The patients also develop comprehensible speech. Lastly, the symptoms of retinitis pigmentosa show itself in the teenage years.

   Type 3: This type is very rare and is generally found in people having their origin in Finland.

   Treatment: Treatment for this includes treatment of the deafness and speech impairment. Thus, usage of hearing aids and cochlear implants is important.

   Since this rare eye disease is inherited, gene therapy is essential. A healthier version of duplicate genes is injected into the retina for reinstalling function. Some cases of Usher Syndrome are caused because of “nonsense” mutation that causes underdevelopment of essential proteins. Medicinal drugs can help in development of these proteins.

   Neuroprotective agents help in maintaining a small portion of vision. Furthermore, stem technology helps in replacement of the affected retinal cells.

4. Juvenile X-Linked Retinoschisis

   Retinoschisis is a situation in which the tissue lining on the inner side of the rear of the eye becomes unconnected and gets divided into two layers. This tissue has the job of sending visual signals to the optic nerve and thereafter to the brain. This rare eye disease mainly affects men and young boys where they suffer from poor eyesight, although very few of them entirely lose their vision. Young boys or infants experience minute loss of central vision which extends throughout their teenage. Finally as an adult their vision stabilizes until they turn old. Patients to this disease are more prone to eye haemorrhage and retinal detachment.

   Treatment: Magnifying lenses and telescopic lenses can serve as temporary aids. Also, proper spectacles can refine the condition of vision in the patient but cannot help in repairing the tissue. Since, this disease is caused as a result of gene mutation, the researchers are working on unconventional therapies to formulate duplications of RS1 genes by safe viruses thereby substituting the defective genes.

5. Achromatopsia

   This inherited rare eye disease causes colour blindness including different eye problems. Mutation in the genes causes achromatopsia in people. The rod cells help us to see at night and have nothing to do with colour recognition. On the other hand the cone cells help us to see during the day, recognize different colours and reading. It is the cone cells that are affected in achromatopsia. The condition does not worsen to the stage of blindness. It can mostly be noticed in infants where they have photophobia and loath bright colours. Another symptom for this disease is Nystagmus where the eyes may uncontrollably move and twirl. Children affected by achromatopsia do not have any other form of difficulty other than blurred or restricted vision.

   Treatment: It is difficult for a person with achromatopsia to see in very bright light. Sometimes people wear tinted glasses to avoid excessive light entering their eyes. If they have to work in very sunny conditions, then they wear highly tinted glasses to enhance their functionality. CNGB3 and CNGA3 genes are responsible for around 75% cases of achromatopsia. Researchers use gene therapy to normalize the condition on the cone cells in the retina.

6. Stargardt Disease

   Stargardt disease causes vision loss. When the photoreceptor cells in the centre of the retina called the macula die it causes the loss of vision. This is most common form of hereditary disease. As symptoms of this rare eye disease, one may notice blind spots in their eye which may increase over time. One may experience difficulty in reading as Stargardt affects the central vision. The condition is progressive but it is very unlikely for someone to turn completely blind due to Stargardt. In the later stage one may experience colour blindness in both the eyes. The degree of progression and the rate of loss of vision also differ from person to person including diseased individuals of the same family. It affects both eyes equally and it is tough to foresee how it will affect the patient at a particular time.

   Treatment: Ultra violet rays of the sun can aggravate the toxicity of the waste products that gathers in the retina and thus people having Stargardt disease are recommended to wear shades that protects the eyes when in direct sunlight. Taking vitamin A supplements can adversely affect the situation and thus must be avoided. A modified form of vitamin A called the deuterated vitamin A is being used in the treatment of this condition. This slows down the gathering of A2E by hindering its grouping downstream in the “visual cycle”.

7. Anophthalmia and Microphthalmia

   Microphthalmia is a problem where either of the eyes or both of them are unusually small or big. Anophthalmia is the lack of either of the eyes of both of them. These develop mainly during pregnancy and can be related to different defects dealing with birth. Both the diseases are caused by either abnormal chromosomes or genetic mutation. Other factors include too much revelation to X-rays, pesticides, chemicals, toxins, drugs, virus or radiation. However, sometimes the cause of this rare disease cannot be determined.

   Treatment: Children are generally fitted an artificial eye for the growth of the socket. Such a patient needs to visit doctors who specialize in pediatrics, orbital, vitreoretinal disease and ophthalmic genetics. The face must develop into the normal shape and thus prosthetics are essentially required else other functionalities of the face may be affected. A child with anophthalmia may also need the help of expanders to enlarge size of the eye socket.

8. Gyrate Atrophy

   It is an autosomal recessive dystrophy which is the result of the mutated genes for ornithine aminotransferase (OAT). Previously it was considered to be a type of choroideremia, the problem is caused due to tenfold elevations of plasma ornithine, that is harmful to the choroid and the RPE. Patients suffering from gyrate atrophy have hyperpigmented areas in their eyes. The generalized hyperpigmentation of the other RPE helps to observe a distinction of gyrate atrophy from choroideremia. At the beginning, people suffering from this disease have huge, paving-stone–like portions of atrophy of the RPE that slowly coagulates to form a significantly risen border at the joint of normal and abnormal RPE. Such patients generally develop night blindness towards the beginning of life and slowly courses to reducing visual clarity.

   Treatment: There is a dietary restriction of arginine for patients of gyrate atrophy. The treatment is done by Vitamin B6 that reduces the plasma ornithine quantity in a lesser percentage of gyrate atrophy patients. Vitamin therapy should be extended over a longer period only if the patient’s ornithine levels drop in response to treatment.

9. Leber Hereditary Optic Neuropathy

   LHON, is a genetic disease which is mainly found in men rather than women, results in sudden vision loss during young adult life. The problem arises due to mutated genetic code of the mitochondria. The eyes need a lot of energy which it fails to receive if the mitochondria are not working properly which kills the retinal ganglion cells. Loss of retinal ganglion cells leads to the degeneration of the optic nerve and hence visual loss. It results in vision loss and also causes pain. Initially one experiences a blurred vision and then it progresses rapidly which finally leaves the patient with only peripheral vision. One cannot see things with minute details in front of them. It also affects the coloured vision of the patient. Different family members may get affected differently because of the difference in the rate of mutation in each mitochondrion in each cell.

   Treatment: Pharmaceutical compounds and gene therapies can be resorted to for curing this disease. Gene therapies aim towards the cell nucleus and further the mitochondria for curing the disease. Idebenone is generally used to cure Alzheimer’s can be used for curing LHON too.

10. Vitelliform Macular Dystrophy or Best Disease

    Vitelliform macular dystrophy is another name for Best Disease and is an inherited rare eye disease. It causes retinal degeneration which affects the macula. Best disease can be observed during the teens, but vision of the patient is not harmed until he turns older. The peripheral vision is unaffected but vision loss does take place differently in different individuals. The central vision gets affected in the first place. A greasy yellowish pigment assembles in the cells under the macula. With time this unusual accumulation damages the cone cells, resulting in a distorted vision. It may affect one eye or both eyes, generally both are not affected at the same time.

    Treatment: It has been researched that the causative agent of best disease is the BEST1 gene, from where it gets its name. Scientists have come up with gene therapy that may cure best disease in future.

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