Corneal iron ring after hyperopic lasik
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Corneal Iron Ring After Hyperopic LASIK. Grand Rounds April 2005 Jay C. Bradley, MD David L. McCartney, MD. Report of Case:. 56 year old male Pre-operative refraction +6.00 –2.50 x 7 +6.00 –1.75 x 165 Pre-operative pachymetry OD – 516 μ m OS – 525 μ m.

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Corneal iron ring after hyperopic lasik

Corneal Iron Ring After Hyperopic LASIK

Grand Rounds April 2005

Jay C. Bradley, MD

David L. McCartney, MD


Report of case
Report of Case:

  • 56 year old male

  • Pre-operative refraction

    +6.00 –2.50 x 7

    +6.00 –1.75 x 165

  • Pre-operative pachymetry

    OD – 516 μm

    OS – 525 μm


Operative summary 2001
Operative Summary (2001):

  • LADARVision 4000

  • Laser-assisted in situ keratomileusis

  • Blend Radius 1.50 mm

  • Zone Size 6.00 mm

  • Ablation depth OD – 91.0 microns

    OS – 90.8 microns

  • No flap or ablation complications


Follow up 2004
Follow-up (2004)

  • Returns to clinic with complaints of decreased near vision OU

  • Does not use distance Rx

  • Normal exam except for trace NSC OU and prominent corneal iron ring OU (~ 5 mm diameter)

  • Patient given Rx for reading glasses



Prior reports of corneal iron ring after hyperopic lasik
Prior Reports of Corneal Iron Ring After Hyperopic LASIK

  • Ozdamar A et al. Cornea. 1999 Mar; 18(2):243-5.

  • 3 patients with pre-op spherical equivalent refraction of +3.37 to +6.50

  • Paracentral iron ring OU at 6 – 7 months after surgery

  • Localized to outside border of central steep zone

  • No change in ring at 1 year follow-up


Prior reports of corneal iron ring after hyperopic lasik1
Prior Reports of Corneal Iron Ring After Hyperopic LASIK

  • Probst LE et al. JCRS. 1999 May; 25:868-870.

  • 1 patient with pre-op Rx of +7.00 –1.50 x 153 OD and +7.50 –1.50 x 165 OS

  • Paracentral corneal iron ring OU at 6 months after surgery (5 mm diameter)

  • 6.0 mm optical zone with 9.5 mm blend zone

  • Ring corresponded to base of hyperopic ablation on corneal topography

  • Increased mean pre-operative SE and ablation depth associated with deposition


Histology
Histology

  • Hemosiderin deposition in basal corneal epithelial cells

  • Iron deposits when there is an abrupt change in corneal surface curvature in area of diminished tear flow and hydrodynamic stasis

(Hyperopic PRK)


Pathogenesis tear pool hypothesis
Pathogenesis: Tear-pool hypothesis

  • Proposed by Gass (1964)

  • Sequestered iron in the tear film is preferentially deposited in areas of the cornea with pooling of the tear film

  • Explains Hudson-Stahli lines corresponding to the lid position at rest

  • Low [iron] in tears, protective effect of mucus, and occurrence of iron lines in eyes without tears question this theory


Pathogenesis basal cell migration theory
Pathogenesis: Basal-Cell-Migration Theory

  • Proposed by Rose and Lavin (1987)

  • Abrasive lid action on corneal surface induces enhanced mitotic activity

  • Dividing, nonmigrating, basal cells become mature and accumulate iron


Pathogenesis tear desiccation hypothesis
Pathogenesis: Tear Desiccation Hypothesis

  • Proposed by Assil (1993)

  • Iron deposits occur in areas of initial tear breakup


Pathogenesis senescent basal cell hypothesis
Pathogenesis: Senescent Basal Cell Hypothesis

  • Proposed by Assil (1993)

  • Iron accumulates in the epithelial cells where there are diminished rates of cell turnover


Iron lines associated with rx tx corneal procedures
Iron Lines Associated with Rx / Tx Corneal Procedures

  • Arcuate along anterior suture border after PK

  • Lamellar keratoplasty

  • Ring adjacent to margin of donor lenticule after epikeratophakia

  • Central stellate pattern after RK (~ 80 %)

  • Inferior line or midperipheral arcuate after intrastromal corneal ring segment (ICRS) placement

  • Central line after uneventful PRK (myopic and hyperopic)

  • Small central ring associated with steep central islands after PRK

  • Myopic and hyperopic LASIK

  • Overnight orthokeratology

  • Conductive keratoplasty



Other corneal iron lines
Other Corneal Iron Lines

  • Fleischer ring

    • Associated with keratoconus

    • First reported in 1906

    • Partial or complete ring encircling base of cone

    • Yellowish to dark brown

    • Best seen with cobalt blue light


Other corneal iron lines1
Other Corneal Iron Lines

  • Hudson-Stähli

    • Iron line along lower third of cornea in otherwise normal eyes

    • Associated with age

    • Area of tear pooling when eye lids at rest


Other corneal iron lines2
Other Corneal Iron Lines

  • Stocker-Busacca line

    • Associated with pterygia

    • Anterior to leading edge

    • Yellow to golden brown


Other corneal iron lines3
Other Corneal Iron Lines

  • Ferry’s line

    • Associated with filtering blebs

    • First reported in 1968


Other corneal iron lines4
Other Corneal Iron Lines

  • Elevated corneal scars

  • Salzmann’s nodular degeneration

  • Corneal foreign body

  • Coats’ white ring

  • Juvenile corneal arcus lipoides




Importance of corneal iron lines
Importance of Corneal Iron Lines

  • Diagnosis of associated ocular condition

  • Identification of corneal donor tissue with prior refractive surgery (ie LASIK flap)

  • Possible estimation of optical size and centration of ablation with hyperopic LASIK



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