PURPOSE-To assess corneal microarchitecture and regional epithelial thickness profile in eyes with keratoconus, postoperative corneal ectasia, and normal unoperated eyes using spectraldomain optical coherence tomography (SD OCT). METHODS-Regional corneal epithelial thickness profiles of eyes with keratoconus (KC) and postoperative corneal ectasia (Ectasia)were measured with anterior segment SC OCT (Optovue RTVue-100, Optovue Inc., Fremont, CA) and compared retrospectively to those of normal eyes (Control). Epithelial thickness was assessed at 21 points, 0.5 mm apart, across the central 6-mm of the corneal apex in the horizontal and vertical meridians.RESULTS-One hundred twenty eyes were evaluated, including 49 eyes from 29 patients with KC, 32 eyes from 16 patients with Ectasia, and 39 eyes from 21 control patients. Average epithelial thickness at the corneal apex was 41.18±6.47μm (range 30 to 51 μm) in eyes with KC, 46.5±6.72μm in eyes with ectasia (range 34 to 60 μm), and 50.45±3.92 μm in normal eyes (range 42 to 55 μm). Apical epithelial thickness was significantly thinner in eyes with KC (p <.0001) and ectasia (p=.0007) than it was in controls. Epithelial thickness ranges in all other areas varied widely for KC (SD, range 21 to 101 μm) and ectasia (SD, range 30 to 82 μm) compared to controls (SD, range 43 to 64), p = .0063 CONCLUSION-Central epithelial thickness was, on average, significantly thinner in ectatic corneas compared to controls; however, both central and regional epithelial thickness was highly irregular and variable in corneas with keratoconus and postoperative corneal ectasia. These thickness variations may alter preoperative topographic features and measurements in unpredictable ways, especially steepest K values. Regional epithelial thickness cannot be assumed to be uniform in ectatic corneas and therefore may require direct measurement when considering New treatment modalities are demonstrating significant potential efficacy for ectatic corneal disorders such as keratoconus and postoperative corneal ectasia, including corneal collagen cross linking (CXL), intracorneal ring segments (ICRS), and limited topography-guided laser ablation, with variable success rates. 1-7 While these ectatic diseases comprise a heterogeneous population, the end stage histopathological changes are quite similar. 8 Histopathologic analysis of corneal ectasia have shown thinning of the epithelium, usually overlying the steepest portion of the cornea, breaks in Descemet's membrane, fragmentation of Bowman layer, and scarring. 8,9 The corneal epithelium has a rapid cell turnover and is highly reactive to asymmetries in the shape of the underlying stromal surface. Epithelial layer remodeling may therefore have a significant impact in corneal topographic measurements, corneal warpage patterns, and early detection of corneal ectatic processes. 10,11 CXL and ICRS both require a minimum corneal depth to prevent corneal endothelial damage for CXL or segment extrusion for ICRS. In both procedures, corneal thickness i...

Objective-To determine whether endothelial cell loss 5 years after successful corneal transplantation is related to the age of the donor. Design-Multicenter, prospective, double-masked clinical trial.Participants-Three hundred forty-seven subjects participating in the Cornea Donor Study who had not experienced graft failure 5 years after corneal transplantation for a moderate-risk condition (principally Fuchs' dystrophy or pseudophakic corneal edema).Testing-Specular microscopic images of donor corneas obtained before surgery and postoperatively at 6 months, 12 months, and then annually through 5 years were submitted to a central reading center to measure endothelial cell density (ECD). Main Outcome Measure-Endothelial cell density at 5 years.Results-At 5 years, there was a substantial decrease in ECD from baseline for all donor ages. Subjects who received a cornea from a donor 12 to 65 years old experienced a median cell loss of 69% in the study eye, resulting in a 5-year median ECD of 824 cells/mm 2 (interquartile range, 613-1342), whereas subjects who received a cornea from a donor 66 to 75 years old experienced a cell loss of 75%, resulting in a median 5-year ECD of 654 cells/mm 2 (interquartile range, 538-986) (P [adjusted for baseline ECD] = 0.04). Statistically, there was a weak negative association between ECD and donor age analyzed as a continuous variable (r [adjusted for baseline ECD] = −0.19; 95% confidence interval, −0.29 to −0.08).Conclusions-Endothelial cell loss is substantial in the 5 years after corneal transplantation. There is a slight association between cell loss and donor age. This finding emphasizes the importance of longer-term follow-up of this cohort to determine if this relationship affects graft survival.Corneal clarity after penetrating keratoplasty can be affected by endothelial cell loss over time. The exact cause of postoperative cell loss is unknown but may be a result of donor or preservation factors, surgical stress, cellular interactions between the donor and recipient, immune reaction, normal or accelerated cellular aging, or glaucoma. The Eye Bank Association of America requires endothelial cell density (ECD) determination via specular microscopy as a standard corneal tissue evaluation method but does not require a minimum cell density for transplant suitability. 1 Clinicians typically prefer donor corneas with a high pre-operative ECD in order to offset posttransplant cell loss under the belief that this will improve the probability of graft survival. Past studies evaluating endothelial cell loss after corneal transplantation have produced conflicting results with regard to the effect of donor age. Some studies suggest that there is no difference in endothelial cell loss comparing older and younger donor tissue, 2-5 whereas other studies suggest that there is a relationship between endothelial cell loss and donor age. 6 -8The Cornea Donor Study (CDS) has evaluated the effect of donor age on 5-year graft survival in eyes undergoing cornea transplantation for a corne...

Significant epithelial remodeling occurs after CXL in eyes with keratoconus and corneal ectasia, creating a similar, more regularized thickness profile in all meridians in the early postoperative period. This pattern of remodeling may facilitate interpretation of corneal curvature and thickness changes after CXL and may be related to visual acuity after CXL.

Purpose: To analyze and compare retreatment rates after wavefront-optimized photorefractive keratectomy (PRK) and LASIK and determine risk factors for retreatment. Methods: A retrospective chart review was performed to identify patients undergoing PRK or LASIK with the wavefront-optimized WaveLight platform from January 2005 through December 2006 targeted for a plano outcome and to determine the rate and risk factors for retreatment surgery in this population. Results: Eight hundred fifty-five eyes were analyzed, including 70 (8.2%) eyes with hyperopic refractions and 785 (91.8%) eyes with myopic refractions. After initial treatment, 72% of eyes were 20/20 or better and 99.5% were 20/40 or better. To improve uncorrected visual acuity, 54 (6.3%) eyes had retreatments performed. No significant differences in retreatment rates were noted based on age ( P =.15), sex ( P =.8), eye ( P =.3), PRK versus LASIK ( P =1.0), room temperature ( P =.1) or humidity ( P =.9), and no correlation between retreatment rate and month or season of primary surgery ( P =.4). There was no correlation between degree of myopia and retreatment rate. Eyes were significantly more likely to undergo retreatment if they were hyperopic (12.8% vs 6.0%, P =.006) or had astigmatism ⩾1.00 diopter (D) (9.1% vs 5.3%, P =.04). Conclusions: Retreatment rate was 6.3% with the WaveLight ALLEGRETTO WAVE excimer laser. This rate was not influenced by age, sex, corneal characteristics, or environmental factors. Eyes with hyperopic refractions or astigmatism ⩾1.00 D were more likely to undergo retreatment. [ J Refract Surg . 2009;25:273–276.]

Significant refractive errors occurred with each of the methods investigated for determining IOL power after LASIK. RH, CL, or AVG 2 provided the most accurate results.