Luca Buzzonetti

Linkage analysis in keratoconus: replication of locus 5q21.2 and identification of other suggestive loci.

PURPOSE Keratoconus (KC) is the most common indication for corneal transplantation in the Western world, with etiologic mechanisms still poorly understood. The disease prevalence in the general population is approximately 1:2000, and familial aggregation, together with increased familial risk, suggests important genetic influences on its pathogenesis. To date, several loci for familial keratoconus have been described, without the identification of any responsible gene in the respective mapped intervals. The aim of this study was to identify causative/susceptibility genes for keratoconus. METHODS A total of 133 individuals (77 affected and 59 unaffected) of 25 families from southern Italy were genotyped using microsatellite markers and included in a genome-wide scan. Nonparametric and parametric analysis using an affected-only strategy were calculated by using genetic algorithm software. RESULTS The chromosomal regions 5q32-q33, 5q21.2, 14q11.2, 15q2.32 exhibited the strongest evidence of linkage by nonparametric analysis (NPL = 3.22, 2.73, 2.62, and 2.32, respectively). The regions 5q32-q33 and 14q11.2 were also supported by multipoint parametric analysis, for which heterogeneity LOD (HLOD) scores of 2.45 (alpha = 0.54) and 2.09 (alpha = 0.46), respectively, were obtained under an affected-only dominant model. CONCLUSIONS This study represents the first KC linkage replication study on the chromosomal region 5q21.2 and reports evidence of suggestive linkage in several regions for which suggestive or significant linkage has been previously detected in different populations.

Comparison of corneal aberration changes after laser in situ keratomileusis performed with mechanical microkeratome and IntraLase femtosecond laser: 1-year follow-up.

Purpose: To compare corneal aberration changes 1 year after myopic laser in situ keratomileusis (LASIK) performed with a mechanical microkeratome and IntraLase femtosecond laser. Methods: Twenty four eyes of 15 patients underwent LASIK with the Hansatome microkeratome, and 23 eyes of 13 patients underwent LASIK with the IntraLase femtosecond laser. A standard ablation was performed with the Bausch & Lomb Technolas 217 excimer laser. Topography data were used to calculate corneal aberrations with a 3.0 mm and 5.00 mm pupil, before and 12 months after surgery. The increasing factor (IF), defined as the ratio between the postoperative and preoperative mean value of the optical aberration, was calculated. The method of Mulhern et al was used to evaluate the centration of ablation. The comalike aberration was correlated with the decentration of ablation. The Student t test was used for the statistical anaylsis. Results: The postoperative mean decentration of ablation was <0.5 mm. The comalike aberration appeared to be positively correlated with the decentration of ablation in both groups with a 5.0-mm pupil (P < 0.05). With a 3.00-mm pupil, the comalike aberration changed in the Hansatome group, whereas with a 5.00-mm pupil, all aberrations statistically significantly changed in both groups (P < 0.05). The IF similarly increased in 2 groups for spherical-like aberration, whereas IF greatly increased for total and comalike aberrations in the Hansatome group. Conclusions: Wavefront corneal aberrations change significantly 1 year after myopic LASIK performed with the Hansatome microkeratome as well as with IntraLase femtosecond lasers. Both of the procedures induce higher-order aberrations in the anterior corneal surface, but the amount of comalike aberration increases more with the Hansatome mechanical microkeratome.

Transepithelial corneal cross-linking in pediatric patients: early results.

PURPOSE To report 18-month follow-up after transepithelial cross-linking (CXL) in young patients. METHODS Thirteen eyes with keratoconus were evaluated (mean patient age: 14.4 ± 3.7 years [range: 8 to 18 years]). Corrected distance visual acuity (CDVA); spherical equivalent refraction; keratometry (K); coma, spherical aberration, and higher order aberrations (HOAs) for a 5.0-mm pupil; and thinnest point were measured preoperatively and 1, 3, 6, 9, 12, and 18 months postoperatively by Scheimplflug camera. Endothelial cell density and anterior segment optical coherence tomography were also evaluated. Paired Student t test was used to compare preoperative and 12- and 18-month postoperative data. P<.05 was considered significant. RESULTS Eighteen months after treatment, CDVA improved significantly, whereas K readings and HOAs showed statistically significant worsening (P<.05). Spherical equivalent refraction, sphere and cylinder, coma, spherical aberration, thinnest point, and endothelial cell density did not show statistically significant changes (P>.05). The mean demarcation line depth was 105 μm. No side effects were observed. CONCLUSIONS Transepithelial CXL appears to be a safe treatment in children. Although improved CDVA was noted 18 months after treatment, this technique does not effectively halt keratoconus progression in children compared to standard CXL.

Arcuate keratotomy for high postoperative keratoplasty astigmatism performed with the intralase femtosecond laser

PURPOSE To evaluate the refractive and keratometric effect of arcuate keratotomy performed using the IntraLase femtosecond laser (Abbott Medical Optics) in patients with high postoperative keratoplasty astigmatism. METHODS Nine eyes of nine patients (mean age 45 +/- 7.5 years; mean spherical equivalent refraction -2.50 +/- 3.60 diopters [D]) who had undergone a penetrating keratoplasty were considered. The subjective refraction was measured, and corneal thickness and keratometric parameters were calculated by the Pentacam (Oculus Optikgeräte). All uncomplicated surgeries were performed with the IntraLase femtosecond laser. Paired 70 degrees arc length incisions were performed at 80% depth of the corneal thickness. The mean optical zone was 5.9 mm. The side cut was 90 degrees. All incisions were performed in the graft itself. Mean change in best spectacle-corrected visual acuity (BSCVA), refractive and keratometric astigmatism, and spherical equivalent refraction was evaluated. Follow-up was 3 months. Refractive and keratometric data were analyzed using vector analysis as described by Alpins. A paired Student t test was used to compare preoperative and 3-month postoperative data. A P value <.05 was considered significant. RESULTS Mean preoperative BSCVA was 20/30, increasing to 20/25 postoperatively (P > .05). The mean refractive astigmatism decreased by 6.00 D (P < .05), whereas the mean keratometric value decreased by 4.60 D (P < .05). The mean spherical equivalent refraction did not change significantly. The surgical vectors in the refractive and keratometric analysis were calculated, showing good predictability. CONCLUSIONS Arcuate keratotomy performed with the IntraLase femtosecond laser could be an effective, safe, and relatively predictable treatment of high postoperative keratoplasty astigmatism.

Femtosecond laser-assisted lamellar keratoplasty: early results.

Purpose: To evaluate the outcomes and safety of lamellar keratoplasty (LK) assisted by a femtosecond laser. Methods: Twenty-one eyes of 21 patients affected by different corneal pathologies (5 posttraumatic corneal scar, 3 postkeratitis corneal leucoma, and 13 keratoconus) underwent LK procedures by using a femtosecond laser. The mean thinnest corneal thickness, evaluated with ultrasound corneal pachymetry and with confocal microscopy, was 434.19 ± 62.60 (SD) μm (range, 333-548 μm). Mean preoperative uncorrected visual acuity was 0.09 ± 0.28 SD and mean preoperative best spectacle-corrected visual acuity was 0.28 ± 0.15 SD. A femtosecond laser was used to perform corneal cuts on both donor and recipient corneas. The donor corneal lamella diameters were 0.20-mm larger and thicker than the recipient to restore a physiologic corneal thickness and shape: mean donor diameter was 8.34 ± 0.28 mm (range, 8.2-8.7 mm) and mean thickness was 352 ± 40.27 μm (range, 220-400 μm). Mean follow-up was 20.86 ± 5.76 months (range, 12-30 months). Results: Early postoperative evaluation showed a clear graft in all cases. A normal corneal pattern topography and a physiologic thickness (mean corneal pachymetry, 542.48 ± 33.20 μm) and transparency were restored. Twelve months after surgery, the mean postoperative uncorrected visual acuity was 0.45 ± 0.34 SD, and the mean best spectacle-corrected visual acuity was 0.63 ± 0.16 SD. Conclusions: Although the numbers in our study are small, our early results indicate that femtosecond laser-assisted lamellar keratoplasty shows promise as a safe and effective surgical choice in the treatment of various corneal pathologies.

Comparison of wavefront aberration changes in the anterior corneal surface after laser-assisted subepithelial keratectomy and laser in situ keratomileusis : Preliminary study

Purpose: To compare changes in anterior corneal wavefront aberrations after myopic laser‐assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK). Setting: Institute of Ophthalmology, Catholic University, Rome, Italy. Methods: This prospective study included 36 eyes of 25 myopic patients: 18 eyes of 12 patients had LASEK and 18 eyes of 13 patients, LASIK. The topography data (CSO EyeMap, version 6.2) were used to calculate corneal aberrations with 3.0 mm and 7.0 mm pupils before and 3 months after surgery. Results: Total corneal aberrations increased similarly after LASEK and LASIK with the 7.0 mm pupil but did not change with the 3.0 mm pupil. Coma‐like and spherical‐like aberrations changed similarly after both procedures, but spherical‐like aberrations increased after LASEK with the 3.0 mm pupil (P<.05, independent t test). With the 7.0 mm pupil, the amount of achieved correction was positively correlated with changes in total corneal aberrations after LASIK (P = .007) and with spherical‐like aberrations after LASEK (P = .03) and LASIK (P<.003). Although there was no significant difference between LASEK and LASIK (P>.05, independent t test), in individual eyes with an achieved correction less than 7.50 diopters (D), spherical‐like aberrations increased more after LASEK than after LASIK. Conclusions: In this preliminary study, myopic LASEK and LASIK changed total and higher‐order corneal aberrations. In both procedures, changes in spherical‐like aberrations were dependent on the achieved correction. However, in individual eyes, spherical‐like aberrations increased more after LASEK than after LASIK for low‐moderate achieved correction, suggesting that these procedures may induce the same optical changes in the anterior corneal surface in different ways.

Iontophoretic transepithelial corneal cross-linking to halt keratoconus in pediatric cases: 15-month follow-up.

Purpose: To report the results 15 months after transepithelial corneal cross-linking by iontophoresis of riboflavin performed in pediatric patients affected by keratoconus. Methods: Fourteen eyes of 14 pediatric patients [mean age 13 ± 2.4 (SD) years; range, 10–18 years] were treated. Riboflavin solution was administered by iontophoresis for 5 minutes, and then UVA irradiation (10 mW/cm2) was performed for 9 minutes. The corrected distance visual acuity measured as decimal number, spherical equivalent, refractive astigmatism, simulated K, corneal coma, spherical aberration, and high-order aberrations for 5.0-mm pupil and the thinnest point were measured preoperatively and 3, 6, 12, and 15 months postoperatively. The endothelial cell density was evaluated. The paired Student t test was used to compare data during the follow-up. Results: Fifteen months after the procedure, the corrected distance visual acuity improved from 0.7 ± 1.7 to 0.8 ± 1.8 (P = 0.005). Spherical equivalent and refractive astigmatism as well as topographic and aberrometric data did not show significant changes. Also, the mean thinnest point and the endothelial cell density remained unchanged. The optical coherence tomography showed a nonhomogeneous but deep hyperreflective band with a fading effect extending through the anterior 180 &mgr;m of the cornea. No side effects were recorded. Conclusions: Transepithelial collagen cross-linking by iontophoresis, unlike other transepithelial techniques, seems to halt pediatric keratoconus progression over 15 months. However, we did not record significant improvement in higher-order aberrations and topographic indices.

PATTERN ELECTRORETINOGRAM IN TREATED OCULAR HYPERTENSION: A CROSS-SECTIONAL STUDY AFTER TIMOLOL MALEATE THERAPY

To investigate pattern electroretinogram changes in treated ocular hypertension, we evaluated pattern electroretinogram recordings of 48 hypertensive eyes following an 8-month timolol maleate therapy. During treatment, 27 of 48 eyes had normalized intraocular pressures (15-18 mm Hg), while 21 retained elevated values (21-25 mm Hg). Twenty-eight eyes with untreated hypertension (22-25 mm Hg) lasting at least 8 months, as well as 32 untreated, normotensive eyes served as controls. When compared to untreated normotensive controls, timolol-treated eyes with either elevated or normalized intraocular pressures showed reductions in the mean electroretinographic amplitudes. However, these amplitude reductions were substantially greater in treated eyes with elevated pressures as compared to those with normalized ones. Untreated hypertensive controls showed pattern electroretinogram reductions, with respect to normal values, that were comparable to those of treated hypertensive eyes, but larger than those of treated normotensive ones. These results indicate that, in treated ocular hypertension, pattern electroretinogram losses tend to be associated with moderately increased intraocular pressures in the range of 21-25 mm Hg. Electroretinographic abnormalities may be, at least in part, prevented only by lowering intraocular pressure into a normal range.

A fast visual evoked potential method for functional assessment and follow-up of childhood optic gliomas

OBJECTIVE To evaluate a fast technique of visual evoked potentials (VEPs) recording, in response to steady-state luminance stimuli (SS-LVEPs), for functional assessment and follow-up of childhood optic gliomas (OGs). METHODS Eighteen OG patients (age range: 3.5-18 years), with different degrees of optic pathway damage severity, were examined. Sixteen age-matched normal subjects served as controls. Ten of the 18 OG patients were re-tested 1-3 months after the first examination. SS-LVEPs were elicited by a sinusoidally-modulated flickering (8 Hz) uniform field, generated by a light emitting diode (LED)-array and presented monocularly in a mini-ganzfeld. Amplitude and phase of the Fourier-analyzed response fundamental (1F) and second harmonic (2F) were measured. The full VEP protocol had a median duration of 6 min (range: 4-12). RESULTS When compared to normal control values, median 1F and 2F SS-LVEP amplitudes of OG patients were reduced (P<0.01), with a borderline increase in 2F phase lag (P<0.05). In 11 OG patients with asymmetric optic pathway damage in between-eye comparisons, median 1F amplitude losses were greater (P<0.01) in fellow eyes with more severe damage. No significant interocular difference was observed in control subjects. Median test-retest changes of 1F and 2F component were <20% and 30 degrees for amplitude and phase, respectively. In individual OG patients, 1F and 2F amplitudes were positively correlated (P<0.01) with visual acuity. 1F amplitude losses were correlated (P=0.01) with the severity of optic disc atrophy. Considering both 1F and 2F abnormalities, diagnostic sensitivity of SS-LVEP in detecting OG-induced optic pathways damage was 83.3%. CONCLUSIONS The present findings support the use of this technique, as an alternative to pattern VEPs, for functional assessment and follow-up of OG in uncooperative children.

Femtosecond Laser and Big-Bubble Deep Anterior Lamellar Keratoplasty: A New Chance

Purpose. To report the 12-month follow-up after big-bubble deep anterior lamellar keratoplasty (DALK) assisted by femtosecond laser that we have called IntraBubble. Methods. A 60 kHz IntraLase femtosecond laser (Abbott Medical Optics) firstly created a 30° angled intrastromal channel to insert the air injection cannula, 50 μ above the thinnest corneal site measured by Sirius Scheimpflug camera (CSO, Firenze, Italy), then performed a full lamellar cut 100 μ above the thinnest corneal point, and from the same corneal depth, created a mushroom incision. The lamella was removed, and the smooth cannula of Fogla was inserted into the stromal channel and air was injected to achieve a big bubble. The follow up is 12 months, and sutures were removed by the 10th postoperative month in all patients. Best Corrected Visual Acuity (BCVA), spherical equivalent and, by Sirius Scheimpflug camera (CSO, Firenze, Italy) keratometric astigmatism were evaluated. Results. All procedures were completed as DALK except 2 converted to PK because an inadvertent intraoperative macroperforation occurred. Mean postoperative BCVA was 0.8, mean spherical equivalent was -3.5 ± 1.7 D, and mean keratometric astigmatism was 4.8 ± 3.1 D. Conclusion. The femtosecond laser could standardize the big-bubble technique in DALK, reducing the risk of intraoperative complications and allowing good refractive outcomes.