Intrastromal Corneal Ring for High Astigmatism on Postkeratoplasty

Eighteen eyes of 18 patients, 8 men and 10 women, with high levels (> 5 diopters [D]) of postkeratoplasty astigmatism were studied in a nonrandomized, retrospective, observational case series. Mean age at the time of ICRS implantation was 38 years, range 22 to 49 years. PK was performed to treat keratoconus in 15 patients, corneal scar after trauma in 2 patients, and Fuchs endothelial dystrophy in 1 patient. All patients were spectacle and contact lens intolerant. There was no active corneal disease or problem apart from high astigmatism.

Minimum time of ICRS implantation was 2 years after PK and at least 6 months after sutures removal.

Preoperative examinations included personal medical ocular history, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, keratometry, intraocular pressure (IOP) measurement by applanation tonometry, corneal astigmatism, surface regularity index, surface asymmetry index, tonometry, slit-lamp biomicroscopy, specular microscopy, and fundus examination.

Main outcome measures included UCVA, BSCVA, refraction, keratometry and computerized analysis of corneal topography.

All surgeries were performed by the same surgeon (BAN) at the Goiania Eye Institute, between July 2007 and January 2009. Corneal tunnels were created by means of mechanical dissection in all eyes. Intrastromal corneal ring segments implantation was indicated because of the existence of reduced best spectacle-corrected visual acuity (BSCVA) or contact lens intolerance. Intracorneal ring segments implantations were performed by the same surgeon following the same protocol. All eyes were implanted with the Cornealring (Visiontech Medical Optics, Belo Horizonte, MG, Brazil). Mean follow-up after ICRS implantation was 12 months (range, 09 to 22 months).

The procedure, its goals, and possible complications were explained and all patients signed an informed consent. The amount and axis of astigmatism to be corrected by ICRS was based on manifest refraction.

Inclusion criteria

• > 5 diopters of postkeratoplasty astigmatism
• Patients 21 to 50 years old
• Conventional treatments have failed

Exclusion criteria

• Diabetes
• Autoimmune diseases