Corneal Ectasias


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Many types of corneal ectasias

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  • The effectiveness of soft lenses is limited because the soft lens often takes the same shape of the irregular surface of the cornea. One option is a thicker soft lens which retain more of a rigid shape. There are soft contact lens designs being used for keratoconus, and they can be helpful in mild to moderate cases.
  • Rigid Gas Permeable (RGP or GP) contact lenses do a better job of correcting the underlying irregular cornea than soft contact lenses because they don't bend or change shape. "Rigid" defines the type of lens. "Gas Permeable" describes the lens material. There are many different RGP lens designs.
  • The lenses are designed using complex computer models and manufactured on special computerized lathes. The complex geometry of Rose K lenses takes into account the conical shape of the cornea in all stages of the condition.Lenses can be customised to suit each eye and can correct the myopia and astigmatism associated with the condition. Rose K lenses allow the cornea to 'breathe' oxygen directly through the lens material providing excellent health to the eye. The lenses are easy to insert, remove and clean. 
  • This is a two lens combination which requires an RGP lens to be worn on top of a soft lens. The RGP lens provides clear vision and the soft lens provides a more comfortable feel.
  • For some, this unique single lens design combines the vision benefits of an RGP lens with the comfort of a soft lens. The hybrid lens has an RGP center surrounded by a soft peripheral "skirt".
  • These lenses have a large diameter that covers the white part of the eye (called the sclera). Scleral lenses have many advantages because of their size. Two major benefits are that they do not fall out and dust or dirt particles cannot get under them during wear. They are also surprisingly comfortable to wear because the edges of the lens rests above and below the eye lid margins so they're hardly noticeable when blinking.
  • effective in patients intolerent to contact lenses without significant central corneal scarring.Optical out comes are poor with (residual astigmatism and anisometropia) necessitating contact lens corrction for best visual acuity
  • Corneal Ectasias

    1. 1. By: Ch.Vineela.
    2. 2.  Ectasia: Dilatation or distension or expansion.
    3. 3.  Corneal ectasia: Bulging of cornea. Keratoconus.jpg
    4. 4.  Corneal ectasias include: -Keratoconus -Pellucid marginal corneal degeneration -Keratoglobus
    5. 5.  Irregular conical shape of cornea, secondary to stromal thinning and protrusion.      Onset: puberty Non inflammatory Bilateral-90% Develops asymmetrical. Variable rate of progression  o Aetiology: -Role of heredity not clearly defined , most without +ve family history.Only 10%- AD transmission.
    6. 6. Association with systemic conditions  Systemic associations: Down, Turner, Ehlers danlos, Marfan syndromes, atopy, osteogenesis imperfecta, mitral valve prolapse and mental retardation.  Ocular assosiations: VKC, blue sclera, aniridia, ectopia lentis, leber congenital amaurosis, RP, Eye rubbing.  Hormonal changes (proteases,protease inhibitors)  Rigid contact lens wear.  Presentation:  During puberty it’s unilateral, due to progressive myopia and astigmatism which subsequently becomes irregular. 
    7. 7.   Due to asymmetrical nature- fellow eye is usually normal with negligible astigmatism at presentation. 50% of normal fellow eyes progress to keratoconus within 16yrs.Greatest risk- first 6yrs of onset.
    8. 8.  Risk factors: -Eye rubbing associated with atopy -Sleap apnea -Floppy lid syndrome  o Classification: Based on severity of curvature: - Mild <48D - Moderate 48-54D - Severe >54D
    9. 9. o Based on morphology of the cone: 1) Nipple cones: Small size (5mm) Apex is central or paracentral & Displaced inferonasally
    10. 10. 2) Oval cones: Larger (5--6 mm) Apex is ellipsoid & Decentered inferotemporally
    11. 11. 3)Globus cones: Largest (>6mm) May involve 75% 0f cornea
    12. 12.  Symptoms:     Blurred vision Frequent change in eye glass prescription " Squinting" in order to see better Change in the astigmatic correction of a patient in the 16-25 year-old age range
    13. 13.    Distortion rather than blur at both distance and near vision Double vision Ghost images
    14. 14. Glare  Halos  Starbursts around lights  Itching of the eye/s, vigorous rubbing of eyes  Eye strain.  Head aches and general eye pain 
    15. 15.  Keratometry shows irregular astigmatism, where the principal meridians are no longer 90 degree apart and the mires cannot be superimposed.
    16. 16.  On direct ophthalmoscopy at one foot distance.
    17. 17.  On retinoscopy.
    18. 18. On slit lamp biomicroscopy  Deep stromal stress lines  Generally vertical, but they can be oblique also  Disappear on pressure with globe. 
    19. 19.  Sub-epithelial corneal scarring may occur because of ruptures in Bowman's membrane. Thickening of the corneal nerves makes them more visible.
    20. 20. Yellow brown ring of pigment  Due to deposition of haemosiderin in the epithelium  Which may or may not completely surround the base of the cone (50% of all cases)  Visualised best with cobalt blue filter 
    21. 21.  Corneal scarring occurs in the advanced the advanced cases.
    22. 22.  Bulging of lower lid in down gaze
    23. 23.  shows irregular astigmatism and is most sensitive method to detect early keratoconus and for monitoring progression.
    24. 24.  Significant corneal thinning - up to 1/5th cornea thickness can be seen in the advanced stages.
    25. 25. Sudden loss of vision.  Descements membrane rupture leads to aqueous flow into the cornea.  Heals within 6-10 weeks and the corneal edema clears leading to variable amount of stromal scarring.  Tx- for initial stages of acute episodes -Cycloplegia -Hypertonic(5%) saline ointment -Patching or a soft bandage contact lens  Healing (scarring and flattening of cornea)results in improved VA 
    26. 26.  Investigations: Corneal topographyKeratometer Keratoscope Photokeratoscope Vediokeratography: by using 1)Placido based system 2) Elevation based system: Uses different methods -Optical slit scan -Side band interferometry - Restersterography or rasterphotogrammetry  Orbscan topography system in one of popular eqipment in this elevation based system which uses slit scan technology. 
    27. 27.  Corneal thickness measurement and examination -Pachymetry -Pentacams -Optical coherence tomography -Ultrasound biomicroscopy -Slit lamp examination
    28. 28.    Spectacles: In early cases. Contact lenses: No one lens is best suited for every type of keratoconus. The needs of each individual are carefully weighed to find the lens that offers the best combination of visual acuity, comfort and corneal health. Soft contact lenses
    29. 29.  Rigid gas permeable lenses
    30. 30.  Special  contact lenses: RoseK lenses
    31. 31.  Piggy back lenses
    32. 32.  Hybrid lenses
    33. 33.  Scleral lenses
    34. 34.  Epikeratoplasty: Patients without corneal scarring.  Keratoplasy: Penetrating or DALK in patients with advanced disease, especially with significant corneal scarring. Optical outcomes are poor, 
    35. 35.  Intra corneal ring segments (Intacs)
    36. 36.  Corneal collagen cross linking
    37. 37.    Corneal collagen cross linking with + laser Corneal collagen cross linking with + Topography guided photo refractive keratectomy. Corneal tranplants
    38. 38.  Peripheral corneal thinning disorder in a crescentic manner, typically involving inferior cornea.
    39. 39. Bilateral Asymmetrical Non-inflammatory Perfectly transperent Non-vascularised Rare, progressive Considerably underestimated often misdiagnosed as keratoconus. o Equal gender distribution o Age 20-40yrs at the time of clinical presentation o Occasionally it may co-exist with keratoconus and keratoglobus. o o o o o o o
    40. 40.  Aetiology: - Idiopathic  Presentation: -4th-5th decades -Uncorrected visual acuity is often severely reduced -Progressive deterioration in uncorrected and spectacle corrected visual acuity -Refraction and keratometry show against-the-rule astigmatism.  Signs: -Bilateral, slowly progressive crescentic (1-2mm) band of inferior corneal thinning.
    41. 41. -Extending from 4-8 o’ clock between limbus and 1-2 mm of normal cornea between the limbus and the area of thinning. -Acute hydrops are less compared to keratoconus -Corneal ectasia is most marked just central to the band of thinning. -The central cornea is usually of normal thickness -The degree of thinning is usually severe, resulting in upto 80% stromal tissue loss. -The corneal protrusion is more marked- superior to the area of thinning.  Corneal topography- Shows butterfly pattern, with severe astigmatism and diffuse steepening of the inferior cornea.
    42. 42.  Differential diagnosis:  Peripheral corneal melting disorders (eg, Mooren ulcer)  Contact lens-induced warpage  Keratoglobus  Terrien marginal degeneration.
    43. 43.  Tx: o o o Spectacles: Fail early due to increase in irregular astigmatism. Contact lenses: Early- soft toric Advanced cases- RGP’s Surgical options: - Large eccentric penetrating keratoplasty -Crescentic lamellar keratoplasty - Wedge resection of diseased tissue - Epikeratoplasty - Intra corneal ring implantation (Intacs)
    44. 44.  Thinning and protrusion of the entire corneal surface (generalised thinning and protrusion)
    45. 45. Extremely rare Non progressive or minimally progressive Aetiology: -congenital -genetically related to keratoconus o Associations: -Leber congenital amaurosis -Blue sclera o Onset- At birth o o o  o Diagnosis: Signs: - In contrast to keratoconus cornea develops globular rather than conical ectasia.
    46. 46. Corneal thinning is generalized. Cornea is usually transparent. Corneal diameter is normal. Acute hydrops are less compared to pellucid marginal degeneration and keratoconus.  Cornea is more prone to rupture on relatively mild trauma.  Corneal topography: -Shows generalized steepening    
    47. 47.  Differential diagnosis: -Congenital glaucoma (Oedematous cornea), Megalocornea (Not thinned)  Tx: -Scleral CL’s -Surgical results are poor, though large diameter grafting can be attempted
    48. 48.  Unilateral thinning of the posterior cornea. o o o o Least common of all ectasias Developmental, usually non-progressive. Mild to moderate decrease in visual acuity Less astigmatism as compared to anterior keratoconus  Tx: - No treatment if abnormality is outside visual axis -Glasses can correct refractive error -Penetrating keratoplasty can be considered in patients with poor vision.
    49. 49.  g1.gif
    50. 50.     Ectasia cicatrix (keratectasia): Ectasia= Bulge forward Cicatrix= Fibrous scar There is marked thinning at the site of ulcer. It bulges forwards even in prescence of normal IOP. There is no adhesion of iris to cornea. The cicatrix may become consolidated and flater later on.
    51. 51.    Post-refractive surgery ectasia is a loss of corneal integrity leading to corneal warpage that often resembles keratoconus. It is more likely to occur following LASIK, radial keratotomy (RK), or astigmatic keratotomy (AK) surgery. These types of refractive surgeries are more likely to cause ectasia because of how they disrupt the cornea.
    52. 52.  Ectatic changes can occur as early as 1 week after LASIK, or they can be delayed up to several years after the initial procedure. In many cases, [corneal transplant] is eventually performed to manage this complication... The continuously growing popularity of refractive surgery procedures, namely LASIK, has caused increased concern regarding the serious complication of keratectasia."
    53. 53. Keratectasia is one of the most feared and dreaded complications of LASIK. The rate of ectasia after LASIK is estimated to be about one in 2,000, but this number could be an underestimate due to underreporting and lack of long-term followup after LASIK.  Pressure inside the eye called intraocular pressure (IOP), which pushes on the back surface of the cornea. A normal healthy cornea easily withstands this force. But after LASIK, the thinner, weaker cornea may begin to give way to this pressure, leading to steepening or bulging of the front surface of the cornea with associated increase in myopia and irregular astigmatism 
    54. 54.  Major Risk factors  Abnormal topography: ▪ Keratoconus (KCN) ▪ Forme fruste keratoconus ▪ Pellucid marginal degeneration  Residual stromal bed thickness: ▪ No magic number but most surgeons consider 250 or 300 microns as the minimum ▪ Note: many eyes do fine below these levels and eyes have developed ectasia above these levels ▪ Measure the stromal bed after the flap is cut
    55. 55.  Minor risk factors:      Younger patients. Asymmetry Enhancements Myopia Treatment is the same as keratoconus     Rigid contact lenses Intacs Keratoplasty: DALK or PKP Collagen cross-linking
    56. 56. ECTASIA REGISTRY: A registry for reporting cases of ectasia after LASIK had its debut recently. The purpose of the registry “is to identify risk factors that are not currently known and to serve as a basis for clinical trials in the future,” said Dr. Stulting, who is directing the project.  There are two anticipated phases to the project. The first phase will establish a database for submission of information on patients who developed ectasia after LASIK. These cases will be evaluated against a control group of LASIK patients who did not develop ectasia, in an effort to validate known risk factors and discover new ones. Phase two will include prospective clinical trials of LASIK in cases involving unproven risk factors.  Ophthalmologists who care for patients with ectasia are encouraged to participate in the online registry by entering data on their patients at 
    57. 57.   Gina M. Rogers, MD and Kenneth M. Goins, MD November 11, 2012  Chief Complaint: Decreasing vision after laserassisted in-situ keratomileusis (LASIK) History of Present Illness: 56-year-old woman. presentation: post bilateral LASIK for myopia at an outside institution.  After LASIK- vision in her left eye was great and had remained good.  She felt that the vision in her right eye initially was decent, but never as good as the left eye.  
    58. 58.    Underwent an enhancement in her right eye approximately one year after her initial surgery. She felt that the vision did not improve significantly. Over the past three years, the vision in the right eye had become progressively more blurred, and could not be improved despite multiple changes to her eyeglasses prescription.
    59. 59.          Past Medical History: unremarkable Past Surgical History: Microkeratome LASIK of both eyes (OU) in 2001, enhancement in right eye 2002 Examination: Visual Acuity Right Eye (OD):20/200uncorrected 20/70 with -7.00 + 6.00 x 163 20/30 with scleral contact lens Left Eye (OS):20/25uncorrected 20/20 with -0.50 sphere Intraocular Pressure: 14 mm Hg OD and 15 mm Hg OS Pupils: Symmetric at 4 mm, briskly reactive, no relative afferent pupillary defect Confrontation Visual fields: full bilaterally
    62. 62.  Unfortunately, preoperative topographies and surgical records were not available. Nonetheless, her right cornea had developed a very abnormally shaped, ectatic appearance. This patient could attain improved visual acuity with a scleral contact lens; however, the contact lens was not tolerable for more than a few hours per day. Given the severity of the ectasia and corneal topography findings, Intacs was not indicated. Specular microscopy was performed to determine endothelial cell density and was found to be 2746 cells/mm2 in the right eye. The options presented to the patient were full thickness penetrating keratoplasty (PKP) and deep anterior lamellar keratoplasty (DALK).[Javadi et al 2010, Shimazaki et al. 2002] Given the adequate endothelial cell density, the decision to undergo DALK was made.
    63. 63.  DALK surgery was performed using the "big bubble" technique as described by Anwar.[Anwar et al. 2002a, 2002b] Her surgery was uncomplicated. She developed steroid induced ocular hypertension that necessitated a switch of topical steroid formulation as well as transient treatment with topical ocular anti-hypertensives. Her pressure remained controlled on the adjusted steroid regimen and there was no evidence of glaucomatous damage. The initial selective suture removal was performed six months post-operatively, and the process continued until her corneal astigmatism had been sufficiently reduced. One year after DALK, her uncorrected visual acuity was remarkably good, at 20/25
    64. 64. Slitlamp photograph of DALK one year post-surgery. Note clarity is excellent and a moderate amount of sutures are still present.
    65. 65.  A comparison of preoperative and postoperative corneal topography shows the benefit of DALK. Normal prolate corneal morphology has been restored.
    66. 66. Kanski- clical ophthalmology 5th and 7th editions. Diagnostic procedures in opthalmology.  /feature.cfm  /158-post-LASIK-ectasia.htm   /158-post-LASIK-ectasia.htm (For case)   