Marjan Farid

Comparison of Penetrating Keratoplasty Performed with a Femtosecond Laser Zig-Zag Incision versus Conventional Blade Trephination

PURPOSE To evaluate visual outcomes and astigmatism in patients who underwent penetrating keratoplasty (PK) with 2 different incision techniques. DESIGN Retrospective comparison of a consecutive surgical series. PARTICIPANTS Fifty-seven consecutive patients who underwent PK at the University of California, Irvine, academic referral practice. METHODS A comparison of 49 eyes of 43 patients that underwent femtosecond laser zig-zag incision pattern PK versus 17 eyes of 14 patients that underwent conventional Barron suction trephination PK performed contemporaneously. All PKs were closed with an identical, 24-bite running nylon suture technique. MAIN OUTCOME MEASURES Topographically determined astigmatism, best spectacle-corrected visual acuity (BSCVA), and recovery of full visual potential. RESULTS The postoperative follow-up ranged from 1 to 12 months. There was a significant difference in average astigmatism between the groups at postoperative month 1 (P = 0.013) and 3 (P = 0.018). By month 3, the average astigmatism was 3 diopters (D) in the zig-zag group and 4.46 D in the conventional group. Of the patients with normal macular and optic nerve function (n(ZZ) = 32; n(con) = 14), a significant difference in BSCVA was seen at month 1 (P = 0.0003) and month 3 (P = 0.006) with 81% of the zig-zag group versus 45% of the conventional group achieving BSCVA of > or =20/40 by month 3 (P = 0.03). CONCLUSIONS The femtosecond laser generated zig-zag-shaped incision results in a more rapid recovery of BSCVA and induces less astigmatism compared with conventional blade trephination PK. FINANCIAL DISCLOSURE(S) Proprietary commercial disclosure may be found after the references.

Femtosecond laser-assisted corneal surgery.

Purpose of review A look at the recent advances in corneal transplantation surgery using the femtosecond laser technology. Recent findings The femtosecond laser uses near-infrared light to create photodisruption, a process that allows corneal tissue to be cut at precise depths and in various patterns. Penetrating keratoplasty as well as disease targeted lamellar corneal surgery have been performed using this technology in order to improve surgical outcomes and wound healing. It is now possible to create customized trephination patterns, including ‘zig-zag’ and ‘top-hat’, which demonstrate more rapid visual recovery and decreased amounts of astigmatism as compared with conventional blade trephination penetrating keratoplasty. The benefits of these cuts have been extended into the deep anterior lamellar keratoplasty surgery in order to maintain the benefits of the customized cut, whereas preserving the endothelial layer in ectatic and stromal diseases of the cornea. Summary Femtosecond laser-assisted corneal surgery is improving traditional outcomes in transplantation. Continued studies using this ultrafast laser may continue to yield new and exciting possibilities in the treatment of corneal disease.

Deep anterior lamellar keratoplasty performed with the femtosecond laser zigzag incision for the treatment of stromal corneal pathology and ectatic disease

We describe a variation of the big-bubble deep anterior lamellar keratoplasty (DALK) technique using the femtosecond laser zigzag incision. This technique allows precise depth visualization for air-needle placement in the posterior stroma based on the lamellar and posterior laser cuts, thus minimizing the risk for perforation of Descemet membrane. The matching donor and host tissue zigzag cut allows more precise tissue apposition and greater surface area for healing. The angled anterior donor and host junction allows a smooth transition for improved visual outcomes. If the big-bubble- Descemet membrane dissection fails, the surgeon can convert to a full-thickness graft while retaining the benefits of the femtosecond laser incision.

Comparison of corneal surface higher-order aberrations after endothelial keratoplasty, femtosecond laser-assisted keratoplasty, and conventional penetrating keratoplasty.

Purpose: To evaluate and compare corneal higher-order aberrations (HOAs) after Descemet stripping automated endothelial keratoplasty (DSAEK), femtosecond laser–assisted penetrating keratoplasty (FLAK), and conventional penetrating keratoplasty (PKP). Methods: A retrospective comparison of consecutive surgical series of 67 eyes of 59 patients between 1.5 and 19 months after corneal transplant surgery (22, 34, and 11 corneas underwent DSAEK, FLAK, and PKP, respectively, by a single surgeon). The main outcome measures were anterior and posterior corneal surface HOAs (Zernike polynomials, third to eighth order) determined with Scheimpflug photography at 4.0- and 6.0-mm optical zones and best spectacle-corrected visual acuity (BSCVA) (logarithm of the minimum angle of resolution equivalents). Results: DSAEK had fewer total anterior HOAs compared with FLAK [P = 5.27 × 10−5 (4.0 mm) and P = 1.02 × 10−5 (6.0 mm)] and PKP [P = 1.82 × 10−4 (4.0 mm) and P = 1.56 × 10−4 (6.0 mm)] but greater total posterior HOAs than FLAK [P = 0.001 (4.0 mm) and P = 0.007 (6.0 mm)] and PKP [at 4.0-mm optical zone (P = 0.047)]. FLAK had fewer total anterior and posterior HOAs than PKP, but differences were not statistically significant. DSAEK grafts exhibited statistically significantly greater posterior HOAs than either type of PKP. The magnitude of anterior and posterior HOAs weakly correlated with BSCVA. Conclusions: DSAEK induces fewer anterior surface HOAs but greater posterior surface HOAs than FLAK or PKP. Differences between FLAK and PKP are not statistically significant. Anterior and posterior HOAs correlate weakly with poorer visual outcome and likely contribute to decreased BSCVA after keratoplasty.

Patient selection for monovision laser refractive surgery.

Purpose of review To investigate the preoperative characteristics and updated patient selection criteria for presbyopic patients undergoing laser refractive surgery for monovision. Recent findings The role of age, sex, ocular dominance, amount of monovision, and hyperopic versus myopic treatments is reviewed and reported. The presbyopic female patient is less likely to reject monovision. Patients with a strong sighting preference do less well due to reduced interocular blur suppression. Although myopes represent the majority of monovision patients, laser-corrected monovision in hyperopes is a viable and satisfactory option. Summary Refractive surgery monovision correction represents an increasingly popular method for the presbyopic patient. Patient selection based on multiple preoperative characteristics is vitally important to the overall success and patient satisfaction.

Results of Toric Intraocular Lenses for Post-Penetrating Keratoplasty Astigmatism

PURPOSE Evaluate the usefulness of toric intraocular lens (IOL) implantation during cataract surgery in patients after penetrating keratoplasty (PKP). DESIGN Retrospective case review. PARTICIPANTS A total of 21 eyes of 16 patients with prior PKP and moderate to high regular astigmatism after full suture removal underwent phacoemulsification and implantation of a single-piece acrylic toric IOL (SN6AT series; Alcon, Fort Worth, TX). METHODS Patients underwent comprehensive examinations at standard intervals, including visual acuity, manifest refraction, and corneal topography. MAIN OUTCOME MEASURES Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) expressed as the logarithm of the minimum angle of resolution (logMAR) and manifest refraction astigmatism. RESULTS From preoperatively to the last visit (mean, 14.7 ± standard deviation 12.8 months), the 21 eyes had significant improvement in UDVA (logMAR, 0.90 ± 0.48 to 0.23 ± 0.25; P = 0.0001) and CDVA (logMAR, 0.31 ± 0.14 to 0.08 ± 0.13; P = 0.0001). A total of 14 of 21 eyes (67%) and 17 of 21 eyes (81%) had UDVA and CDVA of ≥ 20/30, respectively. Preoperative topographic astigmatism was 4.57 ± 2.05 diopters (D). Postoperative manifest refraction astigmatism was 1.58 ± 1.25 D overall, but lower (0.75 ± 0.54 D) in the T7-T9 subgroup (excluding 1 outlier whose corneal astigmatism doubled after surgery) than in the T4-T6 subgroup (1.88 ± 1.28 D; P = 0.013). A total of 16 of all 21 eyes (76.2%) and 8 of 9 eyes (89%) in the T7-T9 subgroup were within 1 D of postoperative manifest astigmatism as predicted or better. CONCLUSIONS Toric IOLs placed during cataract surgery after PKP and full suture removal can reduce manifest refraction cylinder to predictably low levels with corresponding improvement in UDVA and CDVA in patients with moderate to high regular preoperative topographic astigmatism.

Detection of Corneal Fibrosis by Imaging Second Harmonic–Generated Signals in Rabbit Corneas Treated with Mitomycin C after Excimer Laser Surface Ablation

PURPOSE Recent studies have shown that confocal imaging of second harmonic-generated (SHG) signals can detect corneal collagen organization. The purpose of this study was to assess whether SHG signals can detect differences in corneal fibrosis after excimer laser surface ablation (photorefractive keratectomy [PRK]). METHODS Rabbits received 9-D PRK in one eye followed by treatment with either mitomycin C (MMC) or vehicle. Corneal haze was measured by in vivo confocal microscopy before and 2, 4, 8, and 12 weeks after surgery. Animals were then killed and corneas were evaluated by visible and nonlinear confocal microscopy. RESULTS PRK induced significant haze in vehicle-treated corneas that peaked at 2 weeks and remained elevated at 12 weeks after surgery. MMC treatment significantly (P < 0.05) reduced corneal haze at 2 weeks and was essentially normal by 12 weeks. Imaging of SHG signals in vehicle-treated eyes showed an anterior layer of collagen forming a honeycomb network blending into a dense mat of irregularly arranged collagen fibers that overlaid normal orthogonally arranged collagen lamellae. MMC treatment showed normal collagen organization at the surface. Fibrotic tissue was associated with a high cell density and alignment of intracellular actin filaments with collagen fiber bundles. In MMC-treated eyes, an anterior acellular zone overlaid a sparsely populated stroma containing isolated and enlarged keratocytes. CONCLUSIONS Imaging of SHG signals provides a sensitive means for detection of corneal fibrosis after surface ablation and can be used to assess the effects of antifibrotic therapy on corneal healing after refractive surgery.

Reduction in mean deviation values in automated perimetry in eyes with multifocal compared to monofocal intraocular lens implants.

PURPOSE To evaluate differences in mean deviation values in automated perimetry in healthy eyes with multifocal compared to monofocal intraocular lens (IOL) implants. DESIGN Prospective, age-matched, comparative analysis. METHODS SETTING Single-center, tertiary referral academic practice. PATIENT POPULATION A total of 37 healthy eyes in 37 patients with bilateral multifocal (n=22) or monofocal (n=15) IOL implants were studied. INTERVENTION/OBSERVATION PROCEDURE: Humphrey Visual Field 10-2 testing was performed on all patients. MAIN OUTCOME MEASURES Mean deviation (MD) and pattern standard deviation (PSD) numerical values were evaluated and compared between groups. RESULTS The average MD was -2.84 dB (SD 2.32) for the multifocal IOL group and -0.97 dB (SD 1.58) for the monofocal IOL group (P=.006). There was no significant difference in PSD between the 2 groups (P=.99). Eyes that had the visual field 10-2 testing≥6 months from time of IOL placement showed no improvement in MD when compared to eyes that were tested within 6 months from IOL placement. CONCLUSION Multifocal IOL implants cause significant nonspecific reduction in MD values on Humphrey Visual Field 10-2 testing that does not improve with time or neuroadaptation. Multifocal IOL implants may be inadvisable in patients where central visual field reduction may not be tolerated, such as macular degeneration, retinal pigment epithelium changes, and glaucoma.

Prevalence of positive microbiology results from donor cornea tissue in different methods of corneal transplantation.

Purpose: To evaluate the prevalence of positive microbiology results (culture and/or Gram stain) in donor cornea tissue with newer transplant methods and to assess if the results subsequently correlate with higher incidence of clinical infection. Methods: A retrospective review of the microbiology records of 569 consecutive corneal transplants from July 2006 through July 2010 was performed to evaluate positive microbiology results in routine evaluation of cornea donor tissue. Results: Microbiologic results were available for 544 of 569 transplants. The remaining 25 cases did not have specimens submitted for microbiologic analysis. In cases with results available, 46 (8.5%) positive reports occurred. In 10 of the 46 cases, Gram stain results were positive with subsequent negative cultures. Analysis revealed that the prevalence of positive results was 6 in 137 (4.4%), 14 in 127 (11.0%), and 26 in 271 (9.6%) for femtosecond laser–enabled keratoplasty, Descemet stripping automated endothelial keratoplasty, and conventional penetrating keratoplasty, respectively; 9 femtosecond deep anterior lamellar keratoplasty had no positive results. There was no significant relationship between the types of transplant procedures and the occurrence of positive microbiologic results (P = 0.08). The overall incidence of clinical infection was found to be 0.4% (2 of 569); however, only 1 case (1 of 569 or 0.2%), which was a Candida albicans infection after Descemet stripping automated endothelial keratoplasty, was attributable to the donor. Of 25 cases in which microbiology studies were not performed, none developed a clinical infection. Conclusions: Prevalence of positive microbiologic results and subsequent infections do not appear to be increased with the method of donor handling used for newer techniques for keratoplasty.

Corneal Cross-linking for Keratoconus: A Look at the Data, the Food and Drug Administration, and the Future

In the cornea, cross-linking occurs naturally with aging because of an oxidative deamination reaction that occurs within the end chains of collagen. The use of riboflavin as a photosensitizer to generate reactive oxygen species when activated by ultraviolet light to form these cross-links artificially was described first in the late 1990s in animal studies. Subsequently, Wollensak et al reported on this procedure, now widely known as corneal cross-linking (CXL), for the treatment of keratoconus in humans in 2003. Since then, hundreds of reports have been published on the use of CXL for treating keratoconus, as well as for many other conditions such as other ectasias and infectious keratitis. Although CXL has been approved for use in Europe since January 2007, it was not approved for use by the