Keratoconus presents with the following signs and symptoms:

• Distorted vision, individuals with keratconus suffer from blurred vision.
• Development of problems with vision during night time.
• Eyes become sensitive to light and glare.
• Frequent changes in eye glass and contact lens prescriptions.

Symptoms of keratoconus usually differ with disease progression. In more severe cases, the cornea may rupture, and get accumulated with fluid. In such conditions, the already distorted vision worsens, indicating immediate medical intervention [6].

• Nausea

  If you have a deep injury, or a corneal disease or disorder, you could experience: Pain in the eye Sensitivity to light Reduced vision or blurry vision Redness or inflammation in the eye Headache, nausea, fatigue If you experience any of these symptoms [web.archive.org]

• Blurred Vision

  vision, most commonly bilateral in mild to moderate keratoconus, spectacles or a range of contact lenses may help as well as treatment with riboflavin eye drops. [gpnotebook.co.uk]

  Keratoconus presents with the following signs and symptoms: Distorted vision, individuals with keratconus suffer from blurred vision. Development of problems with vision during night time. Eyes become sensitive to light and glare. [symptoma.com]

  Nearsightedness and problems with how the eye is able to focus light may accompany this disease, causing additional problems with distorted and blurred vision and making a clear diagnosis more difficult. Discover our visual aids for Keratoconus. [in.optelec.com]

  Keratoconus is an eye disease that causes the cornea to thin and bulge into a cone-like shape, resulting in blurred vision. Keratoconus is a progressive disease that begins to effect people in their teens and early twenties. [keratoconuscanada.org]

  This then causes the cornea to bulge into a cone-like irregular shape causing distorted and blurred vision. Keratoconus is a progressive eye disease which affects the shape of the cornea causing blurred vision. [oclvision.com]

• Visual Impairment

  This results in significant visual impairment. Because the cornea is irregular and cone shaped, eyeglasses do not appropriately correct the vision in patients with keratoconus. This is a result of the glasses not conforming to the shape of the eye. [sweye.com]

  This results in significant visual impairment. Who Gets Keratoconus? The actual incidence of KC is not known. It is not a common eye disease, but it is by no means rare. [nkcf.org]

  Since the cornea is responsible for refracting light into the eye, keratoconus results in significant visual impairment. This can make tasks such as driving or reading very difficult. [associatedeyecare.com]

  After resolution of the hydrops, he had significant visual impairment from the resulting irregular astigmatism and scarring. [ncbi.nlm.nih.gov]

  As this progresses, normal eye pressure causes the round shape of the cornea to distort and a cone-like bulge develops, resulting in significant visual impairment. [keratoconus.org.au]

• Visual Impairment

  This results in significant visual impairment. Because the cornea is irregular and cone shaped, eyeglasses do not appropriately correct the vision in patients with keratoconus. This is a result of the glasses not conforming to the shape of the eye. [sweye.com]

  This results in significant visual impairment. Who Gets Keratoconus? The actual incidence of KC is not known. It is not a common eye disease, but it is by no means rare. [nkcf.org]

  Since the cornea is responsible for refracting light into the eye, keratoconus results in significant visual impairment. This can make tasks such as driving or reading very difficult. [associatedeyecare.com]

  After resolution of the hydrops, he had significant visual impairment from the resulting irregular astigmatism and scarring. [ncbi.nlm.nih.gov]

  As this progresses, normal eye pressure causes the round shape of the cornea to distort and a cone-like bulge develops, resulting in significant visual impairment. [keratoconus.org.au]

A preliminary, thorough examination of the eye will be carried out. Thereafter, the following tests are conducted to diagnose the condition [7]:

• Eye refraction test: This is the standard vision test, to check for conditions such as astigmatism and vision disorders. Along with this test, an automatic refractor may be used to measure the amount of light reflected by the eyes.
• Slit lamp test: Such a type of examination is done, after the pupils are dilated with help of eye drops. Following this, the shape of the cornea is studied, and other problems within the eye are also determined.
• Keratometry: This is a test used for measuring the curve of the cornea.
• Corneal mapping: With such a kind of examination, the corneal thickness is studied, using corneal topography and optical coherence tomography [8].

The following methods will be employed for treating keratoconus.

• Lenses: This is one of the most common, as well as effective method for treating keratoconus. In the preliminary stages, soft contact lenses can help correct the distorted vision. When the disease progresses to more advanced stages, rigid gas permeable lenses are fitted to cornea, for correcting the associated symptoms. Piggyback lenses are recommended for individuals, who are uncomfortable with gas permeable lenses. This type of lens is hard in nature, and not all individuals can tolerate them. In such cases, hybrid lenses which have softer outer ring for more comfortable wear are suggested. For advanced stages contact lenses are recommended.
• Surgery: In more advanced and severe cases surgery is indicated. When there is corneal scarring, and extreme corneal thinning, then surgical intervention becomes necessary. Surgical procedures, such as keratoplasty, and corneal inserts are required. Depending on the condition of the individual, the type of surgery is decided [9].
• Collagen cross linking: This is a new form of treatment that employs exposing the individual to ultraviolet rays, to prevent further scarring, and thinning. The efficacy of this method is however being tested, before it is made widely available [10].

Individuals with keratoconus present with mild signs and symptoms during adolescence. However, the condition is diagnosed only during the late teens to early 20s. If younger individuals or children are affected, then the disease progresses at a faster rate and can get severe. The prognosis of the condition is pretty unpredictable; in some, the disease progresses at a faster pace, while in some cases patients remain stable for several years [5].

The exact cause of keratoconus is not known. However, several practices or factors can predispose an individual to contract this chronic noninflammatory eye disorder. These include:

• Excessive rubbing of eyes.
• Contact lens users who have been wearing lenses for several years [2].
• Several eye disorders, such as vernal keratoconjunctivtis, retinopathy and or retinitis pigmentosa.
• Enzyme abnormalities and heredity disease conditions, such as Down syndrome.

In addition, several other factors can also put an individual at risk for contracting this disease condition. Individuals with family history of keratoconus, are at an increased risk for developing the same. Also, certain disease conditions, such as osteogenesis imperfecta, Leber’s congenital amarousis and Ehlers Danlos syndrome, are some of the risk factors for keratoconus.

In majority of the cases, keratoconus occurs as a singular condition. But there are some incidences, when the condition coexists along with ocular and systemic diseases. It has been estimated that about 50 to 200 cases occur per 100,000 populations. Statistical reports have suggested that about 2000 Americans are affected with this eye disorder. There have been small pieces of evidence suggesting that females are more likely to develop this condition than males [3].

The condition of keratoconus is known to affect all the corneal layers. Structural changes occur in the epithelial membrane, along with scarring, that occurs in the Bowman membrane. Oxidative stress is known to cause such sequence of events to occur [4]. Oxidative stress on the other hand, can stimulate or activate the degradative enzymes, which in turn leads to thinning of the corneal cells. Such a kind of phenomenon causes vision distortion, and the condition normally affects both the eyes.

Keratoconus cannot be prevented. However, it is advised that individuals with this condition should treat their eye allergies, and also avoid rubbing their eye often.

Keratoconus affects both the eyes, and majorly strikes individuals aged 10 to 25 years. This degenerative eye disease is diagnosed during the adolescence, and gradual loss of vision occurs, as the disease progresses to more advanced stages. More advanced stages of the disease may require surgical intervention, which includes corneal transplant [1].

• Definition: Keratoconus is a condition, characterized by thinning of the cornea, which leads to vision distortion. As the disease progresses, the cornea becomes cone shaped causing the eye to bulge out.
• Cause: The exact cause of keratoconus is unknown. However, several factors are known to increase the risk of contracting this eye disorder. Factors such as wearing contact lenses for several years, rubbing eye often, other eye disorders and heredity are known to play foul.
• Symptoms: Symptoms of keratoconus include blurred vision, experiencing difficulty in seeing at night, frequent changes in contact lens prescriptions, sensitivity to light and glare, and sudden worsening of vision.
• Diagnosis: A preliminary eye examination, using eye refraction test, is conducted to determine presence of conditions, such as astigmatism. In addition, slit lamp examination and corneal topography are also done to diagnose keratoconus.
• Treatment: Lenses form the most common, and primary basis of the treatment regime. Different types of lenses are suggested, for correcting the distorted vision. When these do not work, then surgical intervention is required. Depending on the condition of the individual, either corneal transplant, or corneal inserts are employed. A new method of treating keratoconus has been designed, known as collagen cross linking. In this method, using riboflavin drops, the individual is exposed to ultraviolet rays.

1. Cristina Kenney M, Brown DJ. The cascade hypothesis of keratoconus. Cont Lens Anterior Eye. Sep 2003;26(3):139-46
2. Macsai MS, Varley GA, Krachmer JH. Development of keratoconus after contact lens wear. Patient characteristics. Arch Ophthalmol. Apr 1990;108(4):534-8.
3. Atilano SR, Coskun P, Chwa M, Jordan N, Reddy V, Le K. Accumulation of mitochondrial DNA damage in keratoconus corneas. Invest Ophthalmol Vis Sci. Apr 2005;46(4):1256-63
4. Kenney MC, Nesburn AB, Burgeson RE, Butkowski RJ, Ljubimov AV. Abnormalities of the extracellular matrix in keratoconus corneas. Cornea. May 1997;16(3):345-51.
5. Moodaley LC, Woodward EG, Liu CS, Buckley RJ. Life expectancy in keratoconus. Br J Ophthalmol. Oct 1992;76(10):590-1. 
6. Zadnik K, Barr JT, Edrington TB, et al. Baseline findings in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. Invest Ophthalmol Vis Sci. Dec 1998;39(13):2537-46
7. Wilson SE, Lin DT, Klyce SD, et al. Topographic changes in contact lens-induced corneal warpage. Ophthalmology 1990; 97:734.
8. Wagner H, Barr JT, Zadnik K. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: methods and findings to date. Cont Lens Anterior Eye. Sep 2007;30(4):223-32.
9. Kelly TL, Williams KA, Coster DJ. Corneal transplantation for keratoconus: a registry study. Arch Ophthalmol. Jun 2011;129(6):691-7
10. Raiskup-Wolf F, Hoyer A, Spoerl E, Pillunat LE. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results. J Cataract Refract Surg. May 2008;34(5):796-801.