The most common corneal disorder seen in examination.
FACE AND FACIAL SYMMETRY
The patient may have high-powered spectacles.
EYELIDS AND ADNEXA
(Do not forget to Evert the eyelid in case of Keratoconus for signs of VKC)
Munson Sign
Floppy Eyelid Syndrome
CONJUNCTIVA
Papillae and their sequelae - VKC
CORNEA
Paracentral Stromal Thinning
Vogt's striae are fine, roughly vertical parallel striations in the stroma that disappear on applying pressure to the globe.
Fleischer Ring – hemosiderin ring in the epithelium surrounding the cone – brown in color and best seen with the blue light.
Prominent Corneal Nerves
Rizzuti's Sign - conical reflection on the nasal cornea when a penlight is shone from the temporal side.
Scars from old hydrops – breaks in the Descemet's membrane with overlying scarring of stroma.
ICRS placement
Keratometry
SCLERA
Blue Sclerae
IRIS AND PUPIL
+/- Aniridia
LENS
+/- Ectopia lentis
VITREOUS
POSTERIOR SEGMENT
Retinitis pigmentosa triad
IOP
Glaucoma –
Why is it challenging to measure IOP in Keratoconus?
Ophthalmoscopy
Distant direct ophthalmoscopy – Oil Droplet Sign (always seen with dilated pupil)
Retinoscopy
Irregular Scissor Reflex
FELLOW
Remember to follow the other eye, which may have some other stage of disease progression.
SYSTEMIC CONDITIONS
Down Syndrome
Marfan Syndrome
Atopic Eczema
Ehlers' Danlos syndrome
Osteogenesis imperfecta
QUESTIONS:
What is the histology feature of Keratoconus?
There is seen Fragmentation of Bowman's layer, thinning of the stroma and overlying epithelium, folds or breaks in Descemet's membrane, and variable amounts of diffuse scarring.
How would you treat a patient with Keratoconus?
The main problem is high astigmatism, which tends to be progressive, and treatment consists of glasses initially, then a hard contact lens, and eventually a corneal graft.
Hydrops are usually treated conservatively with antibiotics and eye patches. When edema settles, the scarring may interfere with vision. A corneal graft may be required.
What is the differential diagnosis of Keratoconus?
Pellucid marginal degeneration
Keratoglobus
Contact lens-induced corneal warpage
Corneal ectasia post-refractive laser treatment
Keratoconus (KC) is a progressive, asymmetrically bilateral ectatic corneal disease characterized by paraxial stromal thinning and steepening.
What is the grading of Keratoconus?
Keratoconus is classified into mild, moderate, and advanced cases.
Mild Keratoconus:
Absent or minimal external and corneal signs
Moderate-to-high myopia with oblique astigmatism on refraction
Irregular astigmatic keratometry values
Corneal inferior steepening, central corneal astigmatic steepening, or bilateral temporal steepening on corneal topography or tomography
Moderate Keratoconus:
Presence of one or more corneal signs of Keratoconus (e.g., enhanced appearance of corneal nerves, Vogt striae, Fleischer ring, corneal scarring)
Superficial corneal scarring (fibular, nebular, or nodular)
Deep stromal scarring
Scarring at the level of the Descemet membrane resembling posterior polymorphous corneal dystrophy
Paraxial stromal thinning
Keratometry values of 45-52 diopters (D)
"Scissoring" or the oil drop sign
Munson Sign
Advanced Keratoconus
Keratometry values greater than 52 D
Enhancement of all corneal signs, symptoms, and visual loss/distortion
Vogt striae; Fleischer ring and scarring
Acute corneal hydrops
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