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Late dehiscence of healed corneal scars
  1. KAZ SOONG,
  2. QAIS FARJO,
  3. ALAN SUGAR
  1. Department of Ophthalmology, University of Michigan Medical School
  1. H Kaz Soong, MD, W K Kellogg Eye Center, 1000 Wall Street, Ann Arbor, Michigan 48105, USA.

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Editor,—The stroma comprises about 90% of the total corneal thickness1 and is responsible for most of the corneal tensile strength. Presumably because of its avascularity, healing of corneal stromal wounds is slower than in other connective tissues. Continued histopathological changes in human corneal laceration wounds have been observed years after injury, despite meticulous original suture closure.2 The wounds appear to undergo perpetual, dynamic remoulding, a fine balance between constructive and destructive processes. We report three cases of late, full thickness corneal wound dehiscence occurring spontaneously or after minor blunt trauma 17–56 years after the original injury.

CASE REPORTS

Case 1

A 61 year old man was referred for spontaneous corneal perforation right eye. At age 5, he had sustained a full thickness corneal laceration in this eye which was repaired with sutures. The patient did well with an uncorrected visual acuity of 20/50 right eye until the time of his corneal perforation 56 years later, whereupon he noted the sudden onset of eye pain and loss of vision in this eye upon awakening 2 days before referral. He denied any recent eye trauma or antecedent vigourous rubbing of the eye. He was in excellent health with no previous history of corneal melting disorders. At the time of his first visit to us, the best corrected visual acuities were light perception right eye and 20/20 left eye. There was an inferonasal, 3 mm linear, vertically oriented corneal scar in the right eye not involving the limbus. The iris was incarcerated and externalised along an inferior 1.0 mm long dehiscence in the corneal scar, dragging the entire pupil into the perforation. The Seidel test showed a slow, spontaneous leakage of aqueous humour from the dehiscence. An emergency lamellar corneal patch graft was performed with excision of the dehisced corneal scar and the prolapsed iris. Subsequent surgeries included pupilloplasty, cataract extraction, excision of cyclitic membranes, and penetrating keratoplasty. Pathological specimens revealed extensive epithelial downgrowth. The eye eventually became phthisical. Rheumatoid factor (RF), antinuclear antibodies (ANA), antinuclear cytoplasmic antibodies (ANCA), erythrocyte sedimentation rate (ESR), complete blood counts (CBC), and chemical profile were all normal.

Case 2

This 42 year old woman sustained a full thickness, 8 mm long, corneal laceration in the left eye at age 25 from an exploding glass bottle. The linear laceration was repaired with multiple 10-0 nylon sutures. During a routine follow up visit 17 years after the injury, the patient was able to see 20/60 without correction and 20/30 with a contact lens in the left eye. The corneal scar appeared well healed and stable. Three months later, she bumped her left eye on the edge of a door, after which she noted mild soreness and a very slow decrease in vision in the left eye. Considering the mildness of the impact, she did not seek medical attention until her vision became noticeably worse. She presented to our clinic 2 weeks after the injury with a visual acuity of 20/20 right eye and counting fingers in the left eye. A self sealing, 5 mm, linear dehiscence of the corneal scar was found to be incarcerated with iris. The Seidel test was positive only upon provocation. The incarcerated iris was surgically released and the dehisced corneal scar was repaired with 10-0 nylon sutures. Two weeks after surgery, the uncorrected visual acuity improved to 20/200 left eye. The RF, ANA, ANCA, ESR, CBC, and chemical profile were normal.

Case 3

While using an electric saw, a 68 year old man sustained a perforating wood chip injury of the cornea in his right eye. The resulting peripheral corneal laceration was repaired with 10-0 nylon sutures. A month later, the patient underwent elective extraction of a traumatic cataract in this eye. Subsequently, the best corrected visual acuity was 20/40 with a hard contact lens and spectacle overrefraction. Seventeen years after the injury, the corneal scar dehisced spontaneously in the absence of recent trauma. A peripheral tectonic penetrating keratoplasty was performed, completely excising the dehisced corneal scar. The patient later underwent a central, 8.0 mm, optical penetrating keratoplasty, combined with implantation of a posterior chamber intraocular lens by sulcus fixation. This resulted in a best corrected visual acuity of 20/20 in this eye.

COMMENT

These three cases illustrate the innate structural weakness of healed corneal scars. Two of the scars dehisced without any mechanical provocation. Although corneal scars become optically dense and hypercellular, they never regain the full original preinjury tensile strength.3 Unsutured wounds, such as radial keratotomy incisions, are particularly weak.4 Even sutured full thickness wounds may not regain more than 50–70% of their original corneal tensile strength.3 In penetrating keratoplasty, rupture after blunt trauma may occur many years after surgery and always occurs at the graft host junction, the weakest point in the cornea.5 In full thickness corneal wounds, the discontinuity in Descemet’s membrane further deprives the cornea of another important source of structural strength. Ancillary factors which may further reduce wound integrity include diabetes mellitus, poor suturing technique, incarceration of uvea or vitreous, and entrapment of epithelium.

References

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