Intracorneal ring segment depth in keratoconus patients: a long-term follow-up study

Area of Science:

• Ophthalmology
• Corneal Surgery
• Laser Technology

Background:

• Keratoconus is a progressive corneal ectasia leading to irregular astigmatism.
• Intracorneal ring segments (ICRS) are used to regularize the cornea and improve visual acuity.
• Femtosecond laser technology offers precise tunnel creation for ICRS implantation.

Purpose of the Study:

• To compare the actual implantation depth of intracorneal ring segments (ICRS) created by femtosecond laser with the intended target depth.
• To evaluate the accuracy of femtosecond laser in achieving precise ICRS placement in keratoconus patients.

Main Methods:

• A retrospective chart review identified keratoconus patients who underwent femtosecond laser ICRS implantation.
• Anterior segment optical coherence tomography (AS-OCT) was used to measure the depth of the implanted ICRS.
• Depth was defined as the distance from the anterior corneal surface to the anterior ring segment.

Main Results:

• Thirty keratoconus patients with a mean follow-up of 25.8 months were analyzed.
• The mean actual ICRS depth was 59.9%, significantly shallower than the target depth of 85.0% (P < 0.001).
• Eighty-three percent (83.3%) of implanted rings were shallower than the intended 70% depth threshold.

Conclusions:

• Femtosecond laser-assisted ICRS implantation results in shallower placement than intended in keratoconus patients.
• Current femtosecond laser depth calculators may require revision to improve accuracy.
• Further investigation into optimizing femtosecond laser parameters for ICRS depth control is warranted.