Prospective Study of Intrastromal Corneal Ring Segments for Keratoconus Scott X. Stevens, MD Bend...

Prospective Study of Prospective Study of Intrastromal Corneal Ring Intrastromal Corneal Ring Segments for KeratoconusSegments for Keratoconus

Scott X. Stevens, MDScott X. Stevens, MD

Bend Ophthalmology, LLCBend Ophthalmology, LLC

Author has no financial interest.

PurposePurpose

Keratoconus is an abnormal thinning Keratoconus is an abnormal thinning of the central and inferior paracentral of the central and inferior paracentral cornea and is a frequent indication cornea and is a frequent indication for penetrating keratoplasty. Long-for penetrating keratoplasty. Long-term risks have prompted term risks have prompted intrastromal ring segments as an intrastromal ring segments as an alternative. A prospective alternative. A prospective independent clinical study was independent clinical study was initiated for patients with initiated for patients with keratoconus or post-LASIK ectasia.keratoconus or post-LASIK ectasia.

Prospective Study of Intrastromal Corneal Ring Segments for Keratoconus

MethodsMethods FDA HDE guidelines established in 2004 were utilized in this FDA HDE guidelines established in 2004 were utilized in this

independent clinical study. The study was initiated February, independent clinical study. The study was initiated February, 2004. An IRB for the surgeon has been in place. The HDE 2004. An IRB for the surgeon has been in place. The HDE guidelines directed that an eye with less than -3D spherical guidelines directed that an eye with less than -3D spherical equivalent have a 0.25 ring placed superiorly and a 0.30 ring equivalent have a 0.25 ring placed superiorly and a 0.30 ring placed inferiorly. Patient eyes with more than -3D spherical placed inferiorly. Patient eyes with more than -3D spherical equivalent have a 0.30 ring placed superiorly and a 0.35 ring equivalent have a 0.30 ring placed superiorly and a 0.35 ring placed inferiorly. The rings are 160placed inferiorly. The rings are 160oo and placed at the 7mm and placed at the 7mm optical zone. All surgeries were completed by the author. Eyes optical zone. All surgeries were completed by the author. Eyes with central corneal scarring were excluded from enrollment. with central corneal scarring were excluded from enrollment. Temporal corneal pachymetry was >450 microns. UCVA, BCVA, Temporal corneal pachymetry was >450 microns. UCVA, BCVA, Keratometry, corneal topography, central corneal pachymetry Keratometry, corneal topography, central corneal pachymetry were acquired. All eyes had become contact lens intolerant. were acquired. All eyes had become contact lens intolerant. Baseline BCVA included piggyback/ gas-permeable contact lens Baseline BCVA included piggyback/ gas-permeable contact lens over-refraction at enrollment. BCVA post-op was acquired with over-refraction at enrollment. BCVA post-op was acquired with the patient’s everyday visual aid (ie glasses, contact lens, the patient’s everyday visual aid (ie glasses, contact lens, manifest refraction). Lasik-ectasia eyes were treated in the manifest refraction). Lasik-ectasia eyes were treated in the same fashion as keratoconus eyes. same fashion as keratoconus eyes.


Methods Methods Fifty-three eyes have been enrolled to date.Fifty-three eyes have been enrolled to date. 5 eyes are no-longer enrolled. Two patients (2 eyes) 5 eyes are no-longer enrolled. Two patients (2 eyes)

have failed to make any follow-up visits. One eye 3-have failed to make any follow-up visits. One eye 3-months post-op with LASIK-ectasia had the LASIK flap months post-op with LASIK-ectasia had the LASIK flap removed by an ER physician requiring DALK to restore removed by an ER physician requiring DALK to restore vision (currently BCVA=20/20). One patient lost his eye vision (currently BCVA=20/20). One patient lost his eye secondary to blunt trauma. secondary to blunt trauma. TheThe final eye was removed final eye was removed from the study secondary to eye-rubbing which from the study secondary to eye-rubbing which required removal of the ring segments as they were required removal of the ring segments as they were exposed for one week. exposed for one week.

Visual acuity is the outcome variable. UCVA and BCVA Visual acuity is the outcome variable. UCVA and BCVA are presented at Baseline, 6-months, 1-year and 2-year are presented at Baseline, 6-months, 1-year and 2-year gates. Statistical comparison was accomplished using a gates. Statistical comparison was accomplished using a matched t-test.matched t-test.


ResultsResults


Baseline = 20/2606-Month = 20/140t=6.2775, p<0.01

ResultsResults


ResultsResults


Baseline = 20/2302-Year = 20/120t=7.2307, p<0.01

ResultsResults


36.1% are 20/20 or better77.8% are 20/25 or better83.4% are 20/30 or better94.5% are 20/40 or better

ResultsResults


71.0% are 20/20 or better86.8% are 20/25 or better94.7% are 20/30 or better100% are 20/40 or better

t=8.6634, p<0.01

ResultsResults


73.7% are 20/20 or better89.9% are 20/25 or better100% are 20/30 or better

ResultsResults 3 eyes lost 1 line of BCVA from Baseline to 6-3 eyes lost 1 line of BCVA from Baseline to 6-

months. 7 eyes had no improvement.months. 7 eyes had no improvement. 20/30 – 20/40 (n=2)20/30 – 20/40 (n=2) 20/25 – 20/30 (n=1)20/25 – 20/30 (n=1)

1 eye lost 2 lines of BCVA from Baseline to 1-1 eye lost 2 lines of BCVA from Baseline to 1-Year. All remaining eyes improved by at least Year. All remaining eyes improved by at least one line.one line.

20/25-20/40 (n=1)20/25-20/40 (n=1) 1 eye lost 1 line of BCVA from Baseline to 2-Year. 1 eye lost 1 line of BCVA from Baseline to 2-Year.

All remaining eyes improved by at least one line. All remaining eyes improved by at least one line. 20/25 – 20/30 (n=1)20/25 – 20/30 (n=1)


ConclusionsConclusions Intrastromal ring segments significantly improve Intrastromal ring segments significantly improve

UCVA and BCVA at every gate (p<0.01)UCVA and BCVA at every gate (p<0.01) BCVA improves over time.BCVA improves over time. At the 2-year gate (n=38), BCVA is 20/30 or better At the 2-year gate (n=38), BCVA is 20/30 or better

in all eyes. Seventy-three percent are 20/20 or in all eyes. Seventy-three percent are 20/20 or better.better.

One eye has needed DALK to repair the damage One eye has needed DALK to repair the damage from removal of the LASIK flap. The eye was from removal of the LASIK flap. The eye was 20/16 BCVA prior to the event and currently sees 20/16 BCVA prior to the event and currently sees 20/20 BCVA.20/20 BCVA.

No eye has needed penetrating keratoplasty to No eye has needed penetrating keratoplasty to date.date.


Prospective Study of Intrastromal Corneal Ring Segments for Keratoconus Scott X. Stevens, MD Bend...

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