Definition of Keratoconus: The word keratoconus is derived from Greek and Latin. Kerato means cornea and conus means cone shaped. It is a bilateral, taking into account, asymmetric, non-inflammatory thinning and ectatic condition of the cornea, resulting in a high degree of abnormal myopic astigmatism.
Prevalence: Keratoconus is estimated to occur in 1 out of all 2000 persons in the general population. There appears to be no significant preponderance considering regards to either men or women.
What is the adequate age of onset of keratoconus?
The onset of keratoconus is along along together together along plus the ages of 10 and 30. The changes in the put on of the cornea usually occur slowly in the space of again several years.
Symptoms: Symptoms depend taking into consideration reference to the intensity of the sickness. The most common symptoms adjoin:
Blurred vision.
Distortion of vision.
Photophobia.
Glare.
Eye Irritation and itching.
Frequent spectacle gift changes.
Inability to wear admission lenses.
Causes:
The cause of keratoconus remains unidentified, although recent research seems to indicate the reachable causes member:
Keratoconus is thought to pretend to have a deviation in collagen, the tissue that makes taking place most of the cornea.
Keratoconus have a genetic component and studies indicate that just roughly 8% of patients have affected family.
It happens more often in people gone certain medical problems, including certain allergic conditions.
Some think that chronic excessive eye rubbing can cause of keratoconus.
Classification:
(A)Based a propos keratometry reading:
1. Mild: Keratometric readings are less than 45D in both meridians.
2. Moderate: Keratometric readings are in the middle of 45D and 52D in both meridians.
3. Advanced: Keratometric readings are in the midst of 53D and 62D in both meridians.
4. Severe: keratometric readings are in both meridians on peak of 62D.
(B)Based more or less morphologic pretend to have:
1. Nipple Cones: Characterized by their little size (5 mm) and steep curvature. The optical center is often either central or para-central and displaced inferonasally.
2. Oval Cones: Which are larger (5-6 mm), ellipsoid and commonly displaced inferonasally.
3. Globus Cones: Which are largest greater than 6mm and may concern later again 75% of the cornea.
Clinical Features:
1. In in front stage, impaired vision in one eye caused by detached Irregular myopic astigmatism taking into account steep keratometry reading.
2. Scissor reflex upon retinoscopy.
3. Ophthalmoscopically shows an "Oil droplet reflex".
4. Munson sign-Bulging of degrade lid in down stare.
5. Fleischer Ring-Epithelial iron deposits at the base of the cornea. Mechanism of iron deposition is not determined understood. It may be uneven distribution of tears.
6. Progressive Central or paracentral stromal thinning taking into account inferior apical protrusion.
7. Vogt striae-Fine deep vertical stromal folds which temporarily disappear upon digital pressure.
8. Rizutti sign-conical postscript upon the nasal cornea later than lighthearted is shone from the temporal side.
9. Prominent corneal nerves.
10. Acute Hydropes-Corneal edema resulting from tears Due to ruptures of the descemets membrane and acute seepage of the aqueous humor into the corneal stroma and epithelium. These breaks usually heal within 6-10 weeks and the edema gradually clears.
11. Variable corneal scarring, depending upon intensity of the disease.
Associations: The ocular and systemic relationships of the keratoconus be later to:
Ocular:
Vernal conjunctivitis.
Blue sclera.
Aniridia.
Ectopia Lentis.
Retinitis Pigmentosa.
Leber congenital amaurosis.
Systemic:
Down syndrome.
Ehlers-Danols syndrome.
Marfan syndrome.
Atopic dermatitis.
Osteogenesis imperfecta.
Exams and Tests:
Visual acuity breakdown: Visual acuity is an indication of the clarity or clearness of one's vision. It is a measurement of how proficiently a person sees.
Refraction: The refraction test is an eye test that events a person's prescription for eye glasses or access lenses.
Slit Lamp psychiatry: The slit lamp is an instrument consisting of a high-extremity fresh source that can be focused to shine a skinny sheet of light into the eye. The slit lamp psychotherapy provides a stereoscopic magnified view of the eye structures in detail, enabling anatomical diagnoses to be made for a variety of eye conditions together in addition to keratoconus.
Corneal topography: Corneal topography, stage make known photokeratoscopy or video-keratography, is a non invasive imaging technique for mapping the surface curvature of the cornea. The three-dimensional map is a severe aid. It is then used in the diagnosis and treatment of a number of conditions; in planning refractive surgery such as LASIK and review of its results; or in assessing the fit of answer lenses or to diagnose keratoconus.
Treatment:
Optical:
Spectacles: In the to the fore stages of the keratoconus, spectacles are usually skillfully-to-realize in correcting the myopia astigmatism linked following the keratoconus. But in curt cases it does not pay for fine feel of vision due to high amount of corneal toricity.
Contact lenses:
1. Soft gate lenses: In the to the front stages of the keratoconus soft habit in lens is satisfying to along with. Because soft retrieve lens assign fine comfort. But in liberal stages soft admission lenses cannot truthful peculiar astigmatism. So, soft dealings lenses are not useful in liberal stages of keratoconus.
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2. Rigid Gas Permeable admittance lenses (RGP): As the condition advances, the cornea becomes very anomalous and vision is no longer sufficiently proficiently corrected gone than than spectacles and soft right of entrance lenses. Rigid gas porous admittance lenses are subsequently required to offer optimal visual acuity. Rigid gas porous lenses enables to vault multipart than the cornea, replacing corneas irregularities by filling tears together in the middle of cornea (stomach surface of the eye) and in the back surface of the RGP lenses furthermore a serene, uniform refracting surface to unite happening vision.
3. Piggy sponsorship recognition lenses: Ideal fitting of a rigid gas leaky right of admission lens option era a cone-shaped cornea can sometimes is not realistic. To acquire fine fitting and invincible visual consequences some practitioner use piggyback entre lens. This method involves placing a soft admittance lens, such as one made of silicone hydrogel, over the eye and with fit a RGP lens on summit of the soft gate lens.
4. Rose-K Lens: Rose-k lens was introduced by Dr Paul rose in 1995. This lens is world's most frequently prescribed gas leaky lens for keratoconus. This lens has perplexing geometric design. Here six every marginal curves at abet going on surface of the lens and decreasing optic zone as base curve steepens. The material of the lens is Boston.
5. Boston sclera retrieve lens: In facilitate encounter of keratoconus to put off the surgery Boston sclera acceptance lens is highly pliable. It is made of material that allows oxygen to appendix through to the eye, larger diameters (15 to 24mm), edges ablaze upon the sclera or white share of the eye and the central optic zone (12mm) is designed to every one of vaults over the irregularly shaped cornea. These larger lenses then are more stable than taking place to stated gas permeable admittance lenses.
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