BESB: Common Eye Conditions Which Lead To Low Vision

Common Eye Conditions Which Lead To Low Vision

compiled by

Donna Balaski, DMD

 

ACHROMATOPSIA: ranges from partial to total color blindness, which is the result of cone malformation in the retina. There is a decreased visual acuity of up to 20/200 photophobia and nystagmus. Visual fields are normal.  Several types exist; they can effect either rods or one, two, or all three types of cones. Vision is more severely impacted if rods are effected.

 

TREATMENT: Hand-held magnifiers, dim illumination, and sunglasses.  Currently red filter spectacles or contact lenses are used to increase sharpness of vision.

 

PROGNOSIS: Non-progressive nystagmus and photophobia decrease with age.

 

 

ALBINISM: The partial or total lack of pigment development, which in turn affects macular development. There is a decreased visual acuity ranging from 20/70 to 20/200. There is photophobia nystagmus refractive error and astigmatism. Visual fields are variable. True albinism involves both the skin and eye structures, this is known as oculocutaneous albinism. If only the eyes are affected, it is called ocular albinism. If only the eyes are affected and there is NO nystagmus, then it is called Albinoidism.

 

TREATMENT: Painted pinhole contact lenses, absorptive lenses, optical aids, and dim illumination.

 

PROGNOSIS: Non-progressive.

 

 

ANIRIDIA: This is a congenital malformation or absence of the iris of the eye. There is a variable decrease in visual acuity, photophobia, nystagmus, cataracts, displaced lens, and underdeveloped retina. Visual fields are normal.  Secondary complications include glaucoma and lens opacification.  If glaucoma develops, then the visual fields are also affected.

 

TREATMENT: Pinhole contact lenses, optical aids, sunglasses, and dim illumination.

 

PROGNOSIS: Milder forms develop slow, progressive cataracts. Severe forms develop glaucoma, cataracts, and corneal opacification.

 

 

ASTIGMATISM: Distortion of visual images caused by the refractive portion of the eye. The majority of cases occur due to irregularities in the shape of the cornea. Usually, the eye is out of focus for a vertical portion of an object, but even more out of focus for a horizontal portion of an object. This causes the edges of the image to be distorted and perceived as a blur. Signs of this are a decrease in visual acuity, which can be variable up to 2400 depending upon the severity of the astigmatism. Often astigmatism is associated with myopia or hyperopia. Frequently, signs and symptoms are blurred vision, headaches, tired eyes, or a sandy or gritty feeling of the cornea of the eye when the eyes are used for any extended periods of time, such as in reading. If a child's problem is listed as congenital myopia, that means the child also has nystagmus. The visual acuity cannot be improved because there is an underdevelopment of the macula. Treatment of astigmatism often can correct a person's visual acuity to 20/20 but with those that cannot be corrected, visual acuity can be as far as 20/400.

 

TREATMENT: Cylindrical glasses and optical aids.

 

PROGNOSIS: Stable.

 

 

CATARACTS: (Congenital) There is a decrease in visual acuity, which is extremely variable. Blurry vision is very common; visual fields are generally normal.  Post-surgical condition consists of inability to accommodate and difficulties with glare due to sunlight or fluorescent lighting.  Secondary complications due to surgery include detachment of the vitreous humor or detachment of the retina itself.

 

TREATMENT: Surgical removal as early as possible with intraocular lens implant.

 

PROGNOSIS:   Congenital cataracts was one of the leading causes of blindness in children. This accounts for 15-20% of the students in school who are blind. People with congenital cataracts frequently get secondary glaucoma. Prognosis for children born in the 90s with cataracts have been greatly improved with the use of intraocular lenses and extended-wear contact lenses; visual acuities of 20/20 to 20/40 are often achieved.  Children born pre-1985, however, are often left with a visual acuity of 20/200 or worse due to the lack of modern techniques. The crucial element in successful treatment of congenital cataracts is treating them early by the age of six weeks.  After the age of six weeks, deterioration of other optical structures occurs.

 

 

CATARACTS: (Traumatic) this is lens opacification due to head injury, a foreign body in the eye, or as a result of an ocular surgical procedure.    There is a decreased visual acuity, redness, and inflammation of the eye. Secondary complications include detachment of the retina, infection, uveitis, and glaucoma.

 

TREATMENT: Surgery, which is removal of the lens and the placement of an intraocular lens after the inflammation subsides.

 

PROGNOSIS: Loss of accommodation.

 

 

COLOBOMA: This is the deformity of various portions of the eye. Which portion is affected is dependent upon the time period when the malformation occurred during development. There is a decrease in visual acuity, nystagmus, photophobia, strabismus, and frequently a decrease in the visual fields.  Secondary complications include cataracts. This condition may be unilateral or bilateral. Vision varies from normal to no light perception at all. Visual defects often exist in multiples such as combination of acuity defect and field defect.

 

TREATMENT: Cosmetic contact lenses, sunglasses, and optical aids.

 

PROGNOSIS: A stable condition.

 

 

CORTICAL VISUAL DEFECTS (Cerebral visual impairment): Cerebral visual impairment or cortical blindness may be congenital or acquired, may be prenatal, perinatal, or postnatal in etiology. The structures affected with cortical blindness are the optic nerve after it exits the eye continuing through the optic chiasm back to the occipital cortex of the brain. All ocular structures are normal. However, the infant demonstrates varying degrees of visual attentiveness. Depending upon the severity of damage to the optic nerve or the cerebral cortex, varying degrees of visual impairment may result. An MRI or CT may make diagnosis to the occipital cortex or the optic nerve tract. In some cases, there may be no finding or presence on these tests.  The child may demonstrate better vision with moving objects rather than stagnant ones.

 

TREATMENT: By the visual rehab instructor will depend upon the defects that exist within the child.

 

PROGNOSIS: Cortical blindness may be transient or permanent. It may be an isolated finding or it is often associated with multiple neurological handicaps.

 

 

DIABETES MELLITUS: This disease mainly infects the retina. Signs are varying vision, decrease in visual acuity, decrease in visual fields, diplopia, inability to accommodate, loss of color vision, refractive errors, hemorrhage of blood vessels in the retina, and retinal detachment. Secondary complications include glaucoma and cataracts.

 

TREATMENT: Intense blood glucose monitoring and insulin therapy. Laser surgery, possibly retinal surgery, vertrectomy, and, with the change in vision, optical aids, and glasses.  Note almost all people after two to three treatments of panretinal photocoagulation exhibit photophobia and are affected by glare.  Sunglasses are important in bright sunlight.

 

PROGNOSIS:  Variable. With background retinopathy, which includes edgudate from blood vessels and small microaneurysms, the disease is usually maintained at a stable level. With proliferative retinopathy, which includes growth and hemorrhage of new blood vessels, retinal detachment due to vitreal detachment, the disease is progressive and usually results in severe vision loss.

 

 

DEGENERATIVE MYOPIA (Near-sightedness): This is the elongation of the eye, which results in the stretching of the posterior structures of the eye.  Affects include decreased visual acuity for distant objects, vitreal floaters, and metamorphosis of objects. There is a normal visual field unless the retina becomes detached. Secondary complications include retinal detachment and swelling of the macula.

 

TREATMENT: Prescription corrective lenses, high illumination, and optical aids.

 

PROGNOSIS: Unpredictable rate of progression. Usually digression and more severe cases result in NLP.

 

 

GLAUCOMA (Congenital): This is where tissues of the eye are damaged due to increased intraocular pressure. Usually the optic nerve is the most affected structure. There is excessive tearing, photophobia, opacity of the lens, poor visual acuity, and constriction of the visual fields.

 

TREATMENT: Pharmacologies to reduce the pressure.  If this fails, surgery as soon as possible to prevent further damage, known as trebeculation.  Following treatment, surgically and medically, the patient will need optical aids and corrective lenses.

 

PROGNOSIS:  Variable. Ultimately blindness will develop if left untreated.  When congenital glaucoma is present at birth, prognosis is poor. Even with aggressive therapy, the visual acuity of these eyes will be at the legally blind level (20/200). This is because there is damage to the retina, the optic nerve and the cornea, and often the lens of the eye.  When infantile glaucoma is not present at birth, it is possible to control the intraocular pressure with medications and surgical treatment for approximately 85 % of the cases.  However, the prognosis for vision being better than 20/50 is poor because of amblyopia as well as damage to the optic nerve and cornea.

 

 

HISTOPLASMOSIS: There are scattered lesions located within the macula or the peripheral visual fields, which is due to a fungus invading the retina.   The result is a decrease in visual acuity, scatomas, and a change in color vision.   This is common in the Mississippi River Valley.

 

TREATMENT: High dose of steroids and optical aids for visual deficits.

 

PROGNOSIS: Can be life-threatening if not treated. Optical course is variable depending upon stage of treatment.

 

 

KERATOCONUS: This is where the cornea becomes stretched into a cone shape. There is a progressive decrease in visual acuity as well as a distortion of the entire visual field. This condition is associated with aniridia and retinitis pigmentosa.

 

TREATMENT: With hard contact lenses in the early stages, followed by keratoplasty and eventually a corneal transplant.

 

PROGNOSIS: If left untreated, the cornea will rupture and blindness will occur. Prognosis is good with keratoplasty and corneal transplants.  May require optical aids and will require use of sunglasses in bright light.

 

 

OPTIC ATROPHY: This involves the atrophying of the optic nerve. This can be due to a variety of reasons; optic atrophy has multiple causes, both inherited and non-inherited. There may be an isolated defect of the eye or a multiple facet of defects.  Most commonly the cause is glaucoma, or lack of circulation to the optic nerve itself. Visual symptoms vary greatly, ranging from decreased visual acuity to visual field defects to visual distortion. There can even be photoblindness as a result of optic atrophy. There are varying degrees of visual loss depending on what structure or structures of the eye are involved. Usually visual acuity is in the range of 20/200 or worse.

 

TREATMENT: Depends upon the cause of Optic Atrophy. Often optical aids are needed.

 

PROGNOSIS: Usually the condition is stable, but there are progressive forms which lead to complete blindness.

 

 

OPTIC NERVE HYPOPLASIA: Optic Nerve Hypoplasia is a spectrum of optic nerve abnormalities that ranges from mild with no demonstrative effect on the vision to severe with no light perception. There are varying degrees of visual field defects. Treatment consists of supplying optical aids. In mild cases, there may be amblyopia, which can be treated by patching the sound eye. In severe cases, there may be nystagmus, strabismus, or pupillary defects. Optic nerve hypoplasia may be associated with other conditions to consist of syndromes.

 

TREATMENT: Depends upon the cause of Optic chypoplaisia. Often optic usually adaptive aids are needed.

 

PROGNOSIS: Visual impairment varies depending upon the etiology of the of the disease. Vision loss may be a slow progression to blindness.

 

 

RETINAL DETACHMENT: This is where the retina becomes detached from the surface of the eye due to numerous etiologies such as head trauma, diabetic retinopathy, and congenital myopia. If the macula is affected, there is decreased visual acuity, and most often there is an accompanying loss of visual field where the detachment occurred. Frequently the patient has loss of color perception. At the time of detachment there is also flashing lights, floaters, and sharp pain.

 

TREATMENT: Surgical. The type of surgery depends on the type of detachment or the cause of the detachment. Following recovery of surgery, treatment is with sunglasses and optical aids to improve vision perception.

 

PROGNOSIS: Depending upon the cause and location of the detachment the condition may never re-occur or will re-occur and result in total blindness.

 

 

RETINITIS PIGMENTOSA: Retinitis pigmentosa is an inherited disease which has three modes of genetic transmission. Recessive or sporadic which is the most common type, dominant, which is the least rapid progression and least debilitating, and three, sex-linked, most rapidly progressive and most disabling, but is the least common type. The usual findings in retinitis pigmentosa include attenuation of the retinal vessels; pigmentary changes in the periphery of the retina, myopia, vitreous opacities, posterior subcapsular cataracts, and macular degeneration are often present. The prognosis can best be determined by examining other family members who are affected.

 

TREATMENT:  Treatment is with optical aids, prism glasses, as well as sunglasses, and increased indoor illumination.  Prognosis is poor. There is a slow progressive loss of the fields, which eventually may lead to blindness. Vitamin A & E are often prescribed.

 

PROGNOSIS: Guarded. Frequently, further deterioration occurs. This condition includes over one hundred causes of the deterioration of the pigmented layer of the retina, also called the retinal pigmental epithelium. There is a slow decrease in visual acuity, photophobia, most commonly a decrease in night vision, and decrease in visual fields. This disease, however, most frequently leads to legal and often total blindness.

 

 

RETINOPATHY OF PREMATURITY: This affects the retina due to the growth of blood vessels or lack of growth of blood vessels in the choroid layer of the eye and also affects the vitreous humor. This is the result of high oxygenation levels given to premature infants. There is a decrease in visual acuity, severe myopia, scaring of the retina; often there is retinal detachment with loss of visual fields and complete visual loss. Secondary complications include glaucoma and uveitis. Retinopathy of prematurity was also previously called retrolental fibroplasia. This disease is characterized by a fibril vascular proliferation on the retina or in the choroid layer of the retina.  There are many states in retinopathy of prematurity (ROP). Forms can be mild to severe, the most severe being total blindness, which is usually a result of retinal hemorrhage and retinal detachment.

 

TREATMENT: Optical aids and illumination control devices.

 

PROGNOSIS: Poor.

 

 

STARGARDT'S DISEASE: Stargardt's Disease is another early onset macular dystrophy. However, as originally described in 1909, the majority of families demonstrate an autosomal recessive inheritance pattern. Patients affected with Stargardt's Disease are characterized by atrophic macular lesions and "flecklike" deposits at the level of the retinal pigment epithelium, frequently in the midperiphery of the macula. Presenting symptoms include decreased central vision, central scotomas, and photophobia.

 

TREATMENT: Sunglasses and low vision aids.

 

PROGNOSIS: Varies; usually legal blindness results by late teen years.

 

 

TOXOPLASMOSIS: This, condition is when Toxoplasma gondii invades the retina. Usually the macula is the structure involved. There is a decreased visual acuity if the macula is involved and where the lesions are occurring there are scotomas.  This is the disease that is transmitted by cat fecal matter and if a mother contracts the disease while pregnant, then the fungus nestles in the unborn baby’s retina.

 

TREATMENT: Optical aids usually good response to magnification devices.

 

PROGNOSIS: Non-progressive if treated, though new lesions occasionally may develop.

 

 

UVEITIS: This is the inflammation of the uveal tract, which is the choroid layer, the iris, and ciliary body of the eye. Symptoms are redness of the eye, photophobia, and blurred vision. The blurred vision is caused by a cloudy aqueous humor or sometimes vitreous humor.  Uveitis is often associated with juvenile rheumatoid arthritis.   Usually uveitis is a late occurring complication of juvenile rheumatoid arthritis. Only 8% of the cases incur in early childhood.

 

TREATMENT: Reducing inflammation with the use of steroids. Treatment is with high dose systemic steroids and steroid eyedroppers. Treatment of the secondary complications are via surgery.

 

PROGNOSIS:  Usually good, but varies depending on the cause of uveitis. With early occurring uveitis, prognosis is poor since many of the ophthalmic structures are affected both in the anterior segment and in the posterior segment. Prognosis is poor and vocational planning should occur early since it almost exclusively results in total blindness. With late occurring uveitis, the vision deteriorates over a number of years to eventually lead to a visual acuity of 20/200 or legal blindness. Secondary complications may include glaucoma and cataracts.





Content Last Modified on 2/1/2007 3:59:15 PM