Corneal Dellen

Article initiated by:

Sashwanthi Mohan MBBS, DNB, FICO

All authors and contributors:

Madhuvanthi Mohan, Sujatha Mohan, Vatinee Y. Bunya, MD, MSCE, Augustine Hong, MD, Sashwanthi Mohan MBBS, DNB, FICO

Assigned editor:

Augustine Hong, MD

Review:

Assigned status Update Pending

 by Augustine Hong, MD on April 7, 2022.

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Contributing Editors:	add

Corneal dellen are peripheral excavations in the cornea occurring secondary to tear film disturbance caused by limbal elevations.

Disease Entity

ICD-10: H18.49

Disease

“Dellen” dimple was first described by Ernst Fuchs as shallow, saucer-like excavations at the margin of the cornea.

They are thought to occur due to localized tear film instability especially the mucin layer and dehydration.

Figure 1: Saucer shaped depression in the peripheral cornea with clearly defined margins called dellen. Photo Courtesy: Rajan Eye Care Hospital, Chennai

Etiology

1. Secondary to paralimbal elevation due to
   • Episcleritis or scleritis
   • Thick pingecula or pterygium
   • Subconjunctival hemorrhage
   • Subconjunctival injections
   • Filtering blebs
   • Suture granuloma
   • Limbal tumours
   • Lesions like angioma
   • Subconjunctival silicone oil
2. Post-surgery – cataract/rectus muscle surgery/trabeculectomy
3. Long term contact lens wear
4. Following paralytic lagophthalmos
5. Secondary to severe conjunctival chemosis
6. Idiopathic, in elderly persons
7. Ocular trauma

Pathophysiology

• Paralimbal elevation causes localised break in the precorneal oily tear film especially a focal absence of the mucin layer.

• Cornea epithelium is hydrophobic and in absence of mucin will repel water and localized dehydration occurs producing a dry spot leading to a dry epithelial surface.

• This is followed by thinning of cornea in that area forming a dellen.

Diagnosis

History

History of:

• Ocular surgery
• Ocular trauma
• Previous ocular complaints
• Contact lens wear

Symptoms

• Redness
• Foreign body sensation
• Grittiness

Signs

Slit lamp examination reveals

Figure 2: Slit view of the dellen showing the well defined depression in the peripheral cornea Photo Courtesy: Rajan Eye Care Hospital, Chennai

• Depressed region with clearly defined margins
• Around 2-3 mm in diameter
• Commonly on the temporal side, forming ellipses parallel to the limbus
• Corneal wall is steep, limbal wall is sloping
• Base of lesion appears hazy and dry
• Epithelium is usually intact overlying a thinned area of dehydrated stroma
• Fluorescein pools in the depression and at times there is overlying staining
• Epithelium within the dellen can either be clear or opaque in appearance
• Corneal sensation can be decreased with the dellen compared to rest of the cornea
• Adjoining vascular loops and conjunctival vessels can be injected
• Adjacent cornea is usually normal

Figure 3: Slit lamp photo with cobalt blue filter showing fluorescein pooling in the dellen Photo Courtesy: Rajan Eye Care Hospital, Chennai

Progression

• They usually last only for 24-48 hours and disappear spontaneously.
• However, they can also become chronic with breakdown of epithelium, inflammation of stroma and scarring.
• They usually heal in 2 weeks.

Complications

• If left untreated, the underlying corneal stroma may undergo secondary degeneration, leading to corneal scarring and vascularisation and loss of vision.
• Can lead to corneal perforation.

Management

Treatment needs to be rapid to avoid the above mentioned complications.

General treatment

• Reduction of the paralimbal elevation i.e treating the underlying cause

Medical therapy

• Rapid re-establishment of the mucin layer and a hydrophilic corneal surface by:
  • Frequent lubrication with artificial tears and ointments.
  • Patching of eye can help in faster healing.
  • Large diameter Bandage contact lenses can also help.

• Dellens following filtering blebs – limbal elevation cannot be changed in these cases as bleb is necessary. These patients benefit with frequent artificial tears.

Figure 4: Corneal dellen which was managed with tissue adhesive and bandage contact lens. Photo Courtesy: Rajan Eye Care Hospital, Chennai

Surgery

Surgical excision of paralimbal elevations like pterygium, pingecula, limbal tumours etc.

Minor procedures like tarsorraphy for rapid healing can be considered.

Additional Resources

• Boyd K, Pagan-Duran B, Hazanchuk V. Lubricating Eye Drops. American Academy of Ophthalmology. EyeSmart^® Eye health. https://www.aao.org/eye-health/treatments/lubricating-eye-drops-2. Accessed February 28, 2023.