Corneal opacity | |
---|---|
Other names | Corneal scarring |
Complete corneal opacity in right eye with normal left eye | |
Specialty | Ophthalmology |
Symptoms | Loss of vision |
Complications | Blindness |
Usual onset | Congenital or acquired |
Treatment | Corneal transplantation |
Frequency | 4th main cause of blindness globally (5.1%). [1] |
Corneal opacification is a term used when the human cornea loses its transparency. The term corneal opacity is used particularly for the loss of transparency of cornea due to scarring. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. [2] The term corneal blindness is commonly used to describe blindness due to corneal opacity.
Depending on the density, corneal opacity is graded as nebular, macular and leucomatous.
Nebular corneal opacity is a faint opacity which results due to superficial scars involving Bowman's layer and superficial stroma. A nebular corneal opacity allows the details of the iris to be seen through the opacity. A thin, diffuse nebula covering the pupillary area interferes more with vision than a strictly localized dense leucoma, so long as the latter does not block the whole pupillary area. This is because the leucoma stops all the light which falls upon it, whereas the nebula refracts it irregularly, allowing many of the rays to fall upon the retina where they blur the image formed by the regularly refracted rays. [3]
Macular corneal opacity is a semidense opacity produced when scarring involves about half the corneal stroma. [4]
Leucomatous corneal opacity is a dense white opacity which results due to scarring of more than half of the stroma. [4] A number of different presentations of leucomatous corneal opacity exist:
Signs and symptoms include the following:
Congenital corneal opacity that affecting vision will cause amblyopia. That type of amblyopia is known as form-deprivation amblyopia (or amblyopia ex anopsia). [9]
Secondary changes may be seen in long-standing cases include: hyaline degeneration, calcareous degeneration, pigmentation and atheromatous ulceration. [4]
Pediatric corneal opacities may be congenital or acquired.
Congenital reasons for this condition include:
Acquired reasons for this condition include:
Keratoplasty also known as corneal transplantation is the main treatment option for visual improvement in corneal opacity. In this, the opaque cornea is replaced with donor tissue. Depending on type and density of corneal opacity different types of keratoplasty may be used such as: [28]
Optical iridectomy creates a clear entrance pupil, improving vision in patients with segmental corneal opacities. An area of clear peripheral cornea can produce retinal images compatible with good visual acuity. [30]
Excimer laser phototherapeutic keratectomy (PTK) is useful in superficial (nebular) corneal opacities. [31]
Keratopigmentation or corneal tattooing is a procedure used for centuries to improve the cosmetic appearance of corneal scars. Tattooing will not improve vision. For tattooing procedure Indian black ink, gold or platinum may be used. [4]
Keratoprosthesis is a surgical procedure where damaged or opaque cornea is replaced with an artificial cornea. Artificial corneas currently in commercial use include Boston keratoprosthesis, Osteo-Odonto-Keratoprosthesis (OOKP), AlphaCor, KeraKlear Artificial Cornea etc. [34] [35]
Corneal opacity is the 4th main cause of blindness globally (5.1%). [1] Using the World Health Organization's (WHO; Geneva, Switzerland) blindness definition,1 45 million people worldwide are bilaterally blind, of which 6 to 8 million are blind due to corneal disease. In some African areas, nearly 90% of the total blindness is due to corneal pathology. [36]
The prevalence of congenital corneal opacities (CCO) is estimated to be 3 in 100,000 newborns. This number increases to 6 in 100,000 if congenital glaucoma patients are included. A study of live births in Spain reported that corneal opacities accounted for 3.11% of congenital eye malformations (Bermejo et al, 1998). About 4% of keratoplasties done in the pediatric population in Denmark are due to congenital anomalies (Hovlykke et al, 2014). [37]
In NPCB survey (2001–2002) Corneal opacity was the 6th major cause of blindness in India, which accounts for 0.9% of total blind population. In the RAAB (Rapid Assessment of Avoidable Blindness) survey (2006–2007) Corneal opacity including Trachoma was mentioned as the second major cause of blindness, which accounts for 6.5% of total blindness. [38]
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Corneal opacity | |
---|---|
Other names | Corneal scarring |
Complete corneal opacity in right eye with normal left eye | |
Specialty | Ophthalmology |
Symptoms | Loss of vision |
Complications | Blindness |
Usual onset | Congenital or acquired |
Treatment | Corneal transplantation |
Frequency | 4th main cause of blindness globally (5.1%). [1] |
Corneal opacification is a term used when the human cornea loses its transparency. The term corneal opacity is used particularly for the loss of transparency of cornea due to scarring. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. [2] The term corneal blindness is commonly used to describe blindness due to corneal opacity.
Depending on the density, corneal opacity is graded as nebular, macular and leucomatous.
Nebular corneal opacity is a faint opacity which results due to superficial scars involving Bowman's layer and superficial stroma. A nebular corneal opacity allows the details of the iris to be seen through the opacity. A thin, diffuse nebula covering the pupillary area interferes more with vision than a strictly localized dense leucoma, so long as the latter does not block the whole pupillary area. This is because the leucoma stops all the light which falls upon it, whereas the nebula refracts it irregularly, allowing many of the rays to fall upon the retina where they blur the image formed by the regularly refracted rays. [3]
Macular corneal opacity is a semidense opacity produced when scarring involves about half the corneal stroma. [4]
Leucomatous corneal opacity is a dense white opacity which results due to scarring of more than half of the stroma. [4] A number of different presentations of leucomatous corneal opacity exist:
Signs and symptoms include the following:
Congenital corneal opacity that affecting vision will cause amblyopia. That type of amblyopia is known as form-deprivation amblyopia (or amblyopia ex anopsia). [9]
Secondary changes may be seen in long-standing cases include: hyaline degeneration, calcareous degeneration, pigmentation and atheromatous ulceration. [4]
Pediatric corneal opacities may be congenital or acquired.
Congenital reasons for this condition include:
Acquired reasons for this condition include:
Keratoplasty also known as corneal transplantation is the main treatment option for visual improvement in corneal opacity. In this, the opaque cornea is replaced with donor tissue. Depending on type and density of corneal opacity different types of keratoplasty may be used such as: [28]
Optical iridectomy creates a clear entrance pupil, improving vision in patients with segmental corneal opacities. An area of clear peripheral cornea can produce retinal images compatible with good visual acuity. [30]
Excimer laser phototherapeutic keratectomy (PTK) is useful in superficial (nebular) corneal opacities. [31]
Keratopigmentation or corneal tattooing is a procedure used for centuries to improve the cosmetic appearance of corneal scars. Tattooing will not improve vision. For tattooing procedure Indian black ink, gold or platinum may be used. [4]
Keratoprosthesis is a surgical procedure where damaged or opaque cornea is replaced with an artificial cornea. Artificial corneas currently in commercial use include Boston keratoprosthesis, Osteo-Odonto-Keratoprosthesis (OOKP), AlphaCor, KeraKlear Artificial Cornea etc. [34] [35]
Corneal opacity is the 4th main cause of blindness globally (5.1%). [1] Using the World Health Organization's (WHO; Geneva, Switzerland) blindness definition,1 45 million people worldwide are bilaterally blind, of which 6 to 8 million are blind due to corneal disease. In some African areas, nearly 90% of the total blindness is due to corneal pathology. [36]
The prevalence of congenital corneal opacities (CCO) is estimated to be 3 in 100,000 newborns. This number increases to 6 in 100,000 if congenital glaucoma patients are included. A study of live births in Spain reported that corneal opacities accounted for 3.11% of congenital eye malformations (Bermejo et al, 1998). About 4% of keratoplasties done in the pediatric population in Denmark are due to congenital anomalies (Hovlykke et al, 2014). [37]
In NPCB survey (2001–2002) Corneal opacity was the 6th major cause of blindness in India, which accounts for 0.9% of total blind population. In the RAAB (Rapid Assessment of Avoidable Blindness) survey (2006–2007) Corneal opacity including Trachoma was mentioned as the second major cause of blindness, which accounts for 6.5% of total blindness. [38]
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
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: CS1 maint: multiple names: authors list (
link)
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cite book}}
: CS1 maint: location missing publisher (
link)
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: CS1 maint: multiple names: authors list (
link)
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: CS1 maint: multiple names: authors list (
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