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Imaging modalities in keratoconus.

Matalia H, Swarup R - Indian J Ophthalmol (2013)

Bottom Line: Currently, placido disc based topographers are the most commonly used topographers all over the world.There are many different companies making such devices, which follow the different techniques and color for the display.Due to these differences they are not directly comparable to each other.

View Article: PubMed Central - PubMed

Affiliation: Department of Cornea and Refractive Surgery, Narayana Nethralaya Superspeciality Eye Hospital and Post Graduate Institute of Ophthalmology, Bangalore, Karnataka, India.

ABSTRACT
Diagnosis of keratoconus has greatly improved from simple clinical diagnosis with the advent of better diagnostic devices like corneal topographers based on placido disc, elevation based topographers and lately optical coherence tomography (OCT). These instruments are quite sensitive to pick up early keratoconus, which could help refractive surgeons to avoid serious complications like ectasia following keratorefractive surgeries. Each of these instruments has their advantages and disadvantages; in spite of that each one of them has its own place in the clinical practice. Currently, placido disc based topographers are the most commonly used topographers all over the world. There are many different companies making such devices, which follow the different techniques and color for the display. Due to these differences they are not directly comparable to each other. Various quantitative indices based on these topographers have been suggested and validated by different authors to aid in the diagnosis and quantification of keratoconus. OCT with its higher resolution and deeper penetration has created its place in the diagnostic armamentarium for keratoconus.

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Related in: MedlinePlus

Axial curvature map showing typical “crab claw”/“butterfly wing” pattern of pellucid marginal degeneration, which may mimic eccentric keratoconus. A careful slit-lamp examination and elevation based topography may help to differential it with keratoconus
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Figure 5: Axial curvature map showing typical “crab claw”/“butterfly wing” pattern of pellucid marginal degeneration, which may mimic eccentric keratoconus. A careful slit-lamp examination and elevation based topography may help to differential it with keratoconus

Mentions: The most common culprit is contact lens wear (both hard and soft), which induces patterns of inferior steepening that may be very difficult to distinguish from keratoconus. These patterns, however, disappear with time after contact lens wear is discontinued. Topographic pseudokeratoconus may also result from technical errors during topographic procedure, such as inferior eyeball compression while trying to retract the eye lids, misalignment of the eye with inferior or superior rotation of the eye ball [Fig. 4], and incomplete digitization of mires, causing formation of dry spots, which simulates inferior steepening. Other conditions like pellucid marginal degeneration [Fig. 5], Terrien's marginal degeneration, keratoglobus, scarred cornea, and previous ocular surgery.


Imaging modalities in keratoconus.

Matalia H, Swarup R - Indian J Ophthalmol (2013)

Axial curvature map showing typical “crab claw”/“butterfly wing” pattern of pellucid marginal degeneration, which may mimic eccentric keratoconus. A careful slit-lamp examination and elevation based topography may help to differential it with keratoconus
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3775072&req=5

Figure 5: Axial curvature map showing typical “crab claw”/“butterfly wing” pattern of pellucid marginal degeneration, which may mimic eccentric keratoconus. A careful slit-lamp examination and elevation based topography may help to differential it with keratoconus
Mentions: The most common culprit is contact lens wear (both hard and soft), which induces patterns of inferior steepening that may be very difficult to distinguish from keratoconus. These patterns, however, disappear with time after contact lens wear is discontinued. Topographic pseudokeratoconus may also result from technical errors during topographic procedure, such as inferior eyeball compression while trying to retract the eye lids, misalignment of the eye with inferior or superior rotation of the eye ball [Fig. 4], and incomplete digitization of mires, causing formation of dry spots, which simulates inferior steepening. Other conditions like pellucid marginal degeneration [Fig. 5], Terrien's marginal degeneration, keratoglobus, scarred cornea, and previous ocular surgery.

Bottom Line: Currently, placido disc based topographers are the most commonly used topographers all over the world.There are many different companies making such devices, which follow the different techniques and color for the display.Due to these differences they are not directly comparable to each other.

View Article: PubMed Central - PubMed

Affiliation: Department of Cornea and Refractive Surgery, Narayana Nethralaya Superspeciality Eye Hospital and Post Graduate Institute of Ophthalmology, Bangalore, Karnataka, India.

ABSTRACT
Diagnosis of keratoconus has greatly improved from simple clinical diagnosis with the advent of better diagnostic devices like corneal topographers based on placido disc, elevation based topographers and lately optical coherence tomography (OCT). These instruments are quite sensitive to pick up early keratoconus, which could help refractive surgeons to avoid serious complications like ectasia following keratorefractive surgeries. Each of these instruments has their advantages and disadvantages; in spite of that each one of them has its own place in the clinical practice. Currently, placido disc based topographers are the most commonly used topographers all over the world. There are many different companies making such devices, which follow the different techniques and color for the display. Due to these differences they are not directly comparable to each other. Various quantitative indices based on these topographers have been suggested and validated by different authors to aid in the diagnosis and quantification of keratoconus. OCT with its higher resolution and deeper penetration has created its place in the diagnostic armamentarium for keratoconus.

Show MeSH
Related in: MedlinePlus