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First Author: J.Lemos PORTUGAL
Co Author(s): P. Rodrigues C. Menezes B. Vieira J. Serino P. Moreira N. Martins
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Keratoconus is an ectatic debilitating corneal disorder characterized by a progressive corneal thinning that results in corneal protrusion, irregular astigmatism and reduced best spectacle-corrected visual acuity (BSCVA). Spectacles and contact lenses are the usual treatment modalities in the early stages of this disease. In keratoconus patients that cannot tolerate contact lenses, implantation of intrastromal ring segments is a safe, reversible and interesting modality of treatment that does not affect the central visual axis of the cornea. Therefore, intrastromal ring segments are considered a promising surgical alternative aiming to delay, if not avoid, the need for corneal grafting procedures in keratoconus patients. The objective of our study was to evaluate the efficacy of intrastromal corneal ring segment implantation (Intacs, Addition Technology Inc., Des Plaines, U.S.A.) for treating patients with keratoconus.
Department of Ophthalmology of Hospital Pedro Hispano, Matosinhos, Portugal.
Retrospective, nonrandomized comparative trial of patients submitted to surgery between January 2011 and March 2012 (with minimum follow-up of one-year). All 13 patients (10 male and 3 female, mean age 38,4 years) had keratoconus with clear central corneas and were contact lens intolerant. Patients were submitted to Intacs implantation performed by the same surgeon. Differences between preoperative and postoperative (at 1 month, 3 months, 6 months and 1 year) uncorrected visual acuity (UCVA), BSCVA and manifest refraction were measured. Changes in corneal ectasia were measured by reviewing corneotopographic maps (comparing preoperative data with 6 months and 1 year follow-up).
Mean ±standard deviation (SD) preoperative UCVA and BSCVA were 0,92 ±0,26 logarithm of the minimum angle of resolution (logMAR) and 0,43 ±0,18 logMAR, respectively. Postoperative mean BSCVA at 1 month (0,28 ±0,22 logMAR), 3 months (0,23 ±0,24 logMAR), 6 months (0,12 ±0,21 logMAR) and one year (0,13 ±0,22 logMAR) were all significantly better comparing with preoperative BSCVA (p<0,05). Also, BSCVA at 6 months and one-year follow-up were significantly better comparing with 1 and 3 months after surgery (p<0,05). Postoperative mean UCVA at 3 months (0,63 ±0,46 logMAR), 6 months (0,53 ±0,42 logMAR) and one year (0,52 ±0,40 logMAR) were all significantly better comparing with preoperative UCVA (p< 0,05). The mean preoperative spherical equivalent (-5,29 ±4,36 diopters (D)), was reduced to -2,25 ±3,42D at one year follow-up (p<0,05). Postoperative 6 months and one-year examinations showed significant reduction in mean keratometric (K) values (K1, K2 and Kmax), mean corneal astigmatism and mean Baiocchi Calossi Versaci index (BCV) comparatively with preoperative values (p<0,05).
There is a significant improvement in visual acuity and keratometric parameters after implantation of INTACS ring segments for keratoconus. INTACS seem to be an effective treatment option for patients who have keratoconus, clear central cornea and contact lens intolerance.