Intrastromal corneal ring segment implantation by femtosecond laser for keratoconus correction.

PURPOSE: To report the outcomes after the implantation of intrastromal corneal ring segments (KERARING) aided by femtosecond laser for the correction of keratoconus. DESIGN: Prospective consecutive interventional study. PARTICIPANTS: Twenty-one eyes of 16 consecutive keratoconic patients with mean age 32+/-10.2 years. Forty-five percent were keratoconus grade I, 20% grade II, 15% grade III, and 20% grade IV. METHODS: Intrastromal corneal ring segments KERARING were implanted for keratoconus correction after corneal tunnel creation with the aid of femtosecond laser (IntraLase Corp, Irvine CA). MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refractive outcome, complete ophthalmologic examination, videokeratography, and corneal higher order aberrations (HOA) were determined or performed before and after surgery at 1 day, 1 week, and 3 and 6 months. In addition, operative and postoperative complications were recorded. RESULTS: KERARING implantation significantly increased UCVA from 0.06 to 0.3 (P< or =0.0001), BSCVA from 0.54 to 0.71 (P< or =0.0003), and decreased the spherical equivalent by 2.28 diopters (D) and the average keratometric values (K value) by 2.24 D (P<0.001). There was no significant difference between the 3 and 6 months follow-up. Forty percent (8 eyes with a relatively low RMS of total HOA) showed a nonsignificant increase in the RMS of total HOA and 60% (12 eyes with a relatively higher RMS of total HOA> or =3.0 microm) showed significant (P< or =0.01) decrease in the RMS of total HOA due to a significant (P< or =0.003) reduction in coma and comalike aberrations. The amount of change in corneal curvature (biomechanical response) ranged from a decrease of 18% from its initial value to an increase of 2.75% and was not correlated to any preoperative parameter. Localized infectious keratitis occurred in only 1 eye (4.8%), and incision opacification occurred in 8 eyes (38%). CONCLUSION: Intrastromal corneal ring segment implantation with femtosecond laser is an effective method for correcting keratoconus with reduction in corneal HOA in eyes with coma aberration > 3.0 microm.

The risk of retinal detachment in high myopia after small incision coaxial phacoemulsification.

PURPOSE: Report incidence and risk of retinal detachment (RD)after coaxial phacoemulsification in high myopic patients. DESIGN: Retrospective consecutive interventional study. SETTING: Vissum-Instituto Oftalmologico de Alicante, Spain. PATIENT OR STUDY POPULATION: A total of 439 eyes from 274 high myopic patients with spherical equivalent (SE) >or= 6.00 diopters (D) or axial length >or= 26.00 mm. Mean age 62.2, axial length 27.88 +/- 2.11 mm (26.0 mm to 37.9 mm), SE -13.3 +/- 5.6 (-6.00 D to -46.0 D). MAIN OUTCOME MEASURES: Incidence of RD, vitreous loss, and neodymium yttrium aluminum garnet (Nd:YAG) capsulotomy were evaluated after surgery at one, three, six, and 12 months then annually with mean follow-up 61.5 +/- 29.6 months. RESULTS: Incidence of RD was 2.7% (12/439 eyes). In eyes with 50 years of age was 2.52% (nine eyes). Cumulative risk of RD development by Kaplan-Meier analysis in all patients was 0.47%, 0.71%, 1.71%, 2.59%, and 3.28% at three, six, 15, 48, and 63 months until 105 months, respectively. In eyes 50 years of age was 0.58% and 2.96% at six and 52 months until 118 months after cataract surgery, respectively. No significant correlation was found between the occurrence of RD and vitreous loss (P

Corneal biomechanical properties in normal, post-laser in situ keratomileusis, and keratoconic eyes.

PURPOSE: To compare the biomechanical properties of normal, post-laser in situ keratomileusis (LASIK), and keratoconic corneas evaluated by corneal hysteresis and the corneal resistance factor measured with the Reichert Ocular Response Analyzer (ORA). SETTINGS: Instituto Oftalmológico de Alicante, Vissum, Alicante, Spain. METHODS: Two hundred fifty eyes were divided into 3 groups: normal (control group), post-LASIK, and keratoconus. The corneal biomechanical properties were measured with the ORA, which uses a dynamic bidirectional applanation process. The main outcome measures were intraocular pressure, corneal hysteresis, and the corneal resistance factor. RESULTS: The control group had 165 eyes; the LASIK group, 65 eyes; and the keratoconus group, 21 eyes. In the control group, the mean corneal hysteresis value was 10.8 mm Hg +/- 1.5 (SD) and the mean corneal resistance factor, 11.0 +/- 1.6 mm Hg. The corneal hysteresis value was lower in older eyes, and the difference between the youngest age group (9 to 14 years) and oldest age group (60 to 80 years) was statistically significant (P = .01, t test). One month after LASIK, corneal hysteresis and the corneal resistance factor decreased significantly, from 10.44 to 9.3 mm Hg and from 10.07 to 8.13 mm Hg, respectively. In the keratoconus group, the mean corneal hysteresis was 7.5 +/- 1.2 mm Hg and the mean corneal resistance factor, 6.2 +/- 1.9 mm Hg. There were statistically significant differences in both biomechanical parameters between keratoconic eyes and post-LASIK eyes (P<.001, t test). CONCLUSIONS: The corneal hysteresis and corneal resistance factor values were significantly lower in keratoconic eyes than in post-LASIK eyes. Future work is needed to determine whether these differences are useful in detecting keratoconus when other diagnostic tests are equivocal.

Intracorneal asymmetrical rings for keratoconus: where should the thicker segment be implanted?

PURPOSE: To report a 20-year-old man who presented with monocular diplopia in the right eye with uncorrected visual acuity (UCVA) of 0.3 and best spectacle-corrected visual acuity (BSCVA) of 1.0 with -0.50 -3.00 x 45 degrees. METHODS: Clinical examination and corneal topography revealed grade I keratoconus in the right eye. Intracorneal ring segments (INTACS; Addition Technology, Des Plaines, III) were implanted in May 2004 without surgical complications at 415 microm (70% of the corneal thickness), with the 450-microm segment implanted superiorly and the 250-microm segment inferiorly. RESULTS: For 2 months postoperatively, BSCVA remained at 0.4 with +1.50 -4.50 x 25 degrees. The segments were reversed, implanting the 450-microm (thick) segment inferiorly and the 250-microm (thin) segment superiorly. One week later, UCVA was 1.0 and remained stable for 3 months after reimplantation. CONCLUSIONS: This report shows that implanting the thicker segment inferiorly provides better visual results.

Corneal higher order aberrations: a method to grade keratoconus.

PURPOSE: To use the anterior corneal surface higher order aberrations as a tool to detect and grade keratoconus using corneal map analysis videokeratoscopy. METHODS: A prospective observational comparative study of 80 eyes was performed. The eyes were divided into two groups. Group A comprised 40 eyes of 20 asymptomatic individuals with no ocular pathology. Mean sphere was -0.03 diopters (D) (range: +0.75 to -0.75 D), mean cylinder was -0.27 D, mean average K was 43.28 D, and mean uncorrected visual acuity (UCVA) was 1.01. Group B comprised 40 eyes of 25 patients with keratoconus. Mean sphere was -3.70 D (range: +2.00 to -10.00 D), mean cylinder was -3.82 D, mean average K was 49.29, and mean best spectacle-corrected visual acuity (BSCVA) was 0.61. RESULTS: In group A, mean root-mean-square (RMS) of spherical (Z4 and Z6), coma-like (Z3, Z5, and Z7), and higher order aberrations (Z3-7) were 0.38 microm, 0.35 microm, and 0.52 microm, respectively. In group B, mean RMS of spherical, coma-like, and higher order aberrations were 1.06 microm, 2.90 microm, and 3.14 microm, respectively, for a 6.0-mm simulated pupil diameter. Mean RMS differences between the two groups were 0.68 microm (P < or = .0002), 2.55 microm (P < or = .0001), and 2.61 microm (P < or = .0001) for spherical, coma-like, and total higher order aberrations, respectively. In group B, according to Amsler-Krumeich classification, the mean RMS of coma-like aberration was 1.87 microm in grade I (14 eyes), 2.97 microm in grade II (11 eyes), 3.46 microm in grade III (12 eyes), and 5.20 microm in grade IV (3 eyes). CONCLUSIONS: Corneal higher order aberrations, especially coma-like aberrations, are significantly higher in eyes with keratoconus than normal eyes. Coma-like aberrations, with the aid of a corneal aberrometry map, are good indicators for early detection and grading of keratoconus.

Hyperopic LASIK following intracorneal hydrogel lens explantation.

PURPOSE: To report hyperopic LASIK results after intracorneal hydrogel lens explantation in a bilateral hyperopic patient. METHODS: Slit-lamp examination showed diffuse corneal opacity around the lens edge and over the anterior lens surface affecting both eyes with uncorrected visual acuity of 0.4 in the right eye and 0.5 in the left eye. RESULTS: The intracorneal hydrogel lenses were explanted, and 6 months later hyperopic LASIK using the Schwind ESIRIS excimer laser (Schwind, Kleinostheim, Germany) was performed after lifting the same flap for the intracorneal hydrogel lens implantation. Six months after hyperopic LASIK, visual acuity recovered to the initial preoperative best spectacle-corrected levels: right eye 0.8 with +1.50 D sphere and left eye 0.9 with +1.00 -0.50 x 90 degrees. Central corneal transparency also fully recovered. CONCLUSIONS: Hyperopic LASIK is a possible alternative after intracorneal hydrogel lens explantation in hyperopic eyes.

Intracorneal ring segments for keratoconus correction: long-term follow-up.

PURPOSE: To evaluate long-term results and stability of intracorneal ring segment (Intacs) implantation for keratoconus correction. SETTING: Vissum, Instituto Oftalmológico de Alicante and University of Miguel Hernandez, Alicante, Spain. METHODS: This retrospective study comprised 13 eyes operated on between April 2000 and December 2001 that had Intacs implantation for keratoconus correction. The outcomes were evaluated at 6, 12, 24, and 36 months in all eyes and at 48 months (6 eyes). RESULTS: Mean best spectacle-corrected visual acuity (BSCVA) increased from 0.46 (20/50) preoperatively to 0.66 (20/30) postoperatively (P< or =.001). Mean decrease of inferior-superior (I-S) asymmetry was 2.81 diopters (D) (P< or =.02), and the average K-value was 3.13 D (P< or =.001). Mean difference between 6 and 36 months (stability) showed no significant difference regarding BSCVA (P< or =.5) and I-S asymmetry (P< or =.6). Although a significant increase was noticed in the average K by 1.67 D (P< or =.002), at 36 months it did not reach the initial preoperative values. CONCLUSION: Intacs increased the BSCVA and decreased I-S asymmetry with stability up to 36 months. In spite of the decrease of the K-values at 6 months, a further significant increase was detected 36 months after surgery.

Analysis of results related to good and bad outcomes of Intacs implantation for keratoconus correction.

PURPOSE: To evaluate factors influencing good and poor outcomes after intracorneal ring segment implantation to correct keratoconus. SETTING: Instituto Oftalmológico de Alicante (Vissum Corporation), University of Miguel Hernandez, Alicante, Spain. METHODS: A retrospective comparative study of the visual outcome, 25 eyes of 21 patients were implanted after intracorneal ring segments (Intacs, Addition Technology) as a method to correct keratoconus. Outcomes were evaluated 6 months after implantation based on the visual results. Group A comprised 20 eyes that gained 3 lines or more of best spectacle-corrected visual acuity (BSCVA) to correct keratoconus, and Group B comprised 5 eyes that lost 1 line of BSCVA. RESULTS: In Group A, the preoperative mean BSCVA was 0.43 (20/50) and the postoperative mean BSCVA, 0.82 (20/20) (P< or =.0001). In Group B, the preoperative mean BSCVA was 0.36 (20/63) and the postoperative mean BSCVA, 0.24 (20/80) (P< or =.02). The preoperative mean sphere power was 3.90 diopters (D) greater in Group B than in Group A (P< or =.007); the mean spherical equivalent was 4.36 D greater (P< or =.007), and the mean K-reading was 6.91 D greater (P< or =.001). The postoperative reduction in spherical dioptric power was 2.11 D (P< or =.027) and the mean spherical equivalent, 2.81 D (P< or =.003), significant only in Group A. The reduction in mean central K-readings was 4.30 D (P< or =.0001) in Group A and 6.19 D (P< or =.014) in Group B. The correlation of the preoperative mean K value to the postoperative BSCVA was significant at the .01 level by the Pearson test (-0.67). In Group A, all eyes (100%) had a mean K-reading < or =53 D. In Group B, 4 eyes (80%) had a mean K-reading > or =55 D. CONCLUSION: Intacs provided better results in visual acuity and corneal topography quality and significantly reduced the spherical equivalent in eyes with keratoconus with relatively low mean K values (< or =53 D) and a relatively low spherical equivalent. In advanced keratoconus (mean K-reading > or =55 D), poor results can be anticipated.