PURPOSE:To test a new method of intraocular lens (IOL) calculation after corneal refractive surgery using Scheimpflug imaging (Pentacam HR) and partial coherence interferometry (PCI) (IOLMaster) that does not require historical data; that is, the Schuster/Schanzlin-Thomas-Purcell (SToP) IOL calculator.SETTING:Shiley Eye Center, San Diego, California, and Walter Reed National Military Medical Center, Bethesda, Maryland, USA.DESIGN:Retrospective data analysis and validation study.METHODS:Data were retrospectively collected from patient charts including data from Scheimpflug imaging and refractive history. Target refraction was calculated using PCI and the Holladay 1 and SRK/T formulas. Regression analysis was performed to explain the deviation of the target refraction, taking into account the following influencing factors: ratio of posterior-to-anterior corneal radius, axial length (AL), and anterior corneal radius.RESULTS:The regression analysis study included 61 eyes (39 patients) that had laser in situ keratomileusis (57 eyes) or photorefractive keratectomy (4 eyes) and subsequent cataract. Two factors were found that explained the deviation of the target refraction using the Holladay 1 formula; that is, the ratio of the corneal radii and the AL and the ratio of corneal radii for the SRK/T formula. A new IOL adjustment calculator was derived and validated at a second center using 14 eyes (10 patients).CONCLUSIONS:The error in IOL calculation for normal eyes after laser refractive treatment was related to the ratio of posterior-to-anterior corneal radius. A formula requiring Scheimpflug data and suggested IOL power only yielded an improved postoperative result for patients with previous corneal laser refractive surgery having cataract surgery.FINANCIAL DISCLOSURE:No author has a financial or proprietary interest in any material or method mentioned.

Objective: The purpose of the current study was to assess changes in human corneal rigidity after treatment with riboflavin and UVA using a new device, the Corneal Displacement Unit (CDU). Design: Experimental study. The CDU was designed to quantitatively measure the effect of cross-linking (CXL) in complete human donor cornea buttons. This apparatus measures the tissue displacement associated to computer-controlled variations in pressure. Methods: Baseline measurements with the CDU were taken from 10 de-epithelialized human corneas. They were exposed to 0.1% riboflavin drops every 2 min for 1 h with exposure to UVA light during the last 30 min after which CDU measurements were taken again. Results were analyzed using a non-parametric test. Significant tests were set at P ≤ .15 and non-significant correlation coefficients at rho ≤ .15 to reject abnormal measurements. For each of the 10 corneas, pachymetry values and 1988 CDU measurements were collected before and after treatment. Results: Pressure measurements averaged across the corneas were similar before and after treatment (P ≥ .99), and were highly correlated (Spearman rho = .88, P < .001). Corneal displacement observations after treatment were significantly different from baseline, showing a reduction of .084 microns on average (P < .001), and thus demonstrating a reduced displacement in cross-linked corneas. Conclusions: The present study demonstrated a significant increase in the mechanical rigidity of human corneas after CXL. The CDU was able to quantify the mechanical strength of whole corneal buttons ex vivo with minimal damage to the tissue.

Purpose: To investigate the effect of omega-3 oral nutritional supplementation on corneal reepithelialization, visual acuity, and tear stability after photorefractive keratectomy (PRK).Methods: This is a prospective, randomized, single-blinded controlled therapeutic trial using omega-3 oral nutritional supplements (TheraTears Nutrition for Dry Eyes; Advanced Vision Research-Akorn, Ann Arbor, MI) conducted at our center. Eighteen healthy patients with refractive error between -1 and -8 diopters were recruited and had bilateral PRK. The treatment group (n = 9 subjects) received omega-3 2 weeks before surgery through 1 month after PRK. The control group (n = 9 subjects) was not given omega-3. Epithelial defects were photographed on postoperative days 0 to 5. Reepithelialization (area in square millimeters) was assessed by fluorescein staining until healing. Tear breakup time (TBUT) and uncorrected distance visual acuity were measured at 1 week, and 1 and 3 months postoperatively.Results: Epithelial defect in the treatment group eyes healed faster compared with that of the controls (P = 0.04). The treatment group eyes healed at an average rate of 1.19% [SD = 0.002; 95% confidence interval (CI), 1.04%-1.34%] per hour, versus 0.83% (SD = 0.0008; 95% CI, 0.77%-0.89%) for controls (Mann-Whitney rank-sum test, P < 0.001). The treatment group eyes maintained a significantly longer TBUT from week 1 through 3 months (mean = 9.52 seconds, SD = 0.81; 95% CI, 8.93-10.10), compared with the controls (mean = 5.52 seconds, SD = 0.81; 95% CI, 4.93-6.10; P < 0.001), and all reached 20/20 vision versus only 4 in the control group 1 month after surgery (P = 0.03).Conclusions: Omega-3 oral nutritional supplements decreased the average time for epithelial healing, and improved TBUT and visual acuity recovery in PRK. These findings suggested that omega-3 oral nutritional supplementation may be a beneficial adjunct therapy for PRK patients.

The authors report a case of an immunocompetent 38-year-old male who presented with an indolent keratitis that eluded diagnosis after multiple cultures taken over 9 months. He was started initially on medications against Acanthamoeba, after presenting with a nearly complete corneal ring 2 months after trauma. These medications likely partially treated his condition, thereby making laboratory diagnosis more difficult. He was identified as having Encephalitozoon hellum by PCR. The patient subsequently underwent cornea transplant after a full course of medical treatment and recovered best-corrected visual acuity of 20/20.

PURPOSE:To evaluate changes in corneal asphericity (Q) and spherical aberrations after refractive surgery using Scheimpflug imaging. SETTING:University of California, San Diego, Shiley Eye Center, La Jolla, California, USA. DESIGN:Cohort study. METHODS:After wavefront-guided laser in situ keratomileusis, patients within ± 0.50 diopter of plano and with an uncorrected distance visual acuity of at least 20/20 were evaluated. The Q values and corneal spherical aberration Zernike values were obtained using Scheimpflug imaging preoperatively and 1 to 3 months postoperatively. RESULTS:The study enrolled 177 myopic eyes and 32 hyperopic eyes. The mean Q value was -0.28 ± 0.11 (SD) and -0.22 ± 0.15, respectively, preoperatively and +0.35 ± 0.44 and -0.64 ± 0.31, respectively, postoperatively. The asphericity change was highly correlated with preoperative spherical equivalent (r(2) = 0.81; P ≤ .001). The mean corneal spherical aberration was +0.21 ± 0.08 μm in myopic eyes and +0.36 ± 0.11 μm in hyperopic eyes preoperatively and +0.36 ± 0.17 μm and 0.00 ± 0.29 μm, respectively, postoperatively. The corneal spherical aberration changes were correlated with the amount of preoperative refractive error (r(2) = 0.34; P < .001). There was a tendency for Q values and spherical aberrations to become more positive after myopic ablation and more negative after hyperopic ablation. CONCLUSIONS:Myopic and hyperopic corrections induced changes in the Q value and spherical aberrations in opposite directions (ie, positive and negative, respectively). The changes depended on the magnitude of the refractive correction. FINANCIAL DISCLOSURE:No author has a financial or proprietary interest in any material or method mentioned.

PURPOSE: To determine whether treatment with oral gabapentin reduces postoperative pain after photorefractive keratectomy (PRK). METHODS: This prospective, randomized, double-blind, placebo-controlled study comprised 40 patients scheduled for bilateral PRK. Exclusion criteria were previous refractive surgery; diseases that could affect epithelial healing; use of antihistamines, nonsteroidal anti-inflammatory drugs, or steroids; and use of mitomycin C during PRK. Patients were divided into two groups: 20 patients received gabapentin capsules (300 mg) and 20 patients received identical placebo capsules. Visual acuity, slit-lamp examination, and a 12-question, 10-point visual numerical scale questionnaire were evaluated at each postoperative follow-up. Main outcome measures were the severity of pain at each follow-up and during the previous 24 hours. Secondary outcome measures were maximum and minimum severity of pain, healing time, uncorrected distance visual acuity, and the rating of other symptoms and potential side effects. RESULTS: The gabapentin group had less pain during the first 72 hours ( P =.024 to .001). A significant difference in favor of gabapentin was found for the first 48 hours regarding minimum pain severity ( P =.005 and .01 for 24 and 48 hours, respectively) and for the first 72 hours for maximum pain severity ( P =.014, .007, and .001 for 24, 48, and 72 hours, respectively). No significant differences were observed for side effects, symptoms, or healing time except discomfort in favor of gabapentin during the first 24 hours ( P =.043). CONCLUSIONS: Gabapentin significantly reduced postoperative pain after PRK compared to placebo, with no increase in reported side effects.

PURPOSE:To describe a new technique for deep anterior lamellar keratoplasty in the human eye.METHODS:We obtained globes from the San Diego Eye Bank and performed central and peripheral pachymetry measurements at the 8-mm optical zone. We made a radial incision at the edge of the optical zone at 90% depth of central corneal thickness. We enlarged the incision and started lamellar dissection. The curved tunnel was created using dissecting instruments (Addition Technology, Des Plaines, IL), used in Intacs channels. With a sweeping motion, we connected these channels. An 8-mm Barron Radial Vacuum Trephine (Baron Precision Instruments, LLC, Grand Blanc, MI) was placed over the optical zone until the 90% depth of thickness was reached. The cap tissue was detached and viscoelastic was used to separate Descemet membrane and stromal tissue. We photographed the surface for analysis.RESULTS:This technique was easy to perform with little remaining posterior stromal tissue. Residual tissue could easily be dissected, and the vacuum trephine could easily reach the same depth of the pocket. The outer edge of the bed had a clean sharp edge. The stromal bed surface and the inner corneal cap were smooth.CONCLUSIONS:We conclude that this modified technique is easy to perform and results in a more regular stromal surface. This technique may reduce the need for penetrating keratoplasty.