Accelerated Corneal Collagen Cross-linking for Postoperative LASIK Ectasia: Two-Year Outcomes.

PURPOSE: To evaluate the effectiveness and safety of accelerated corneal collagen cross-linking for postoperative LASIK ectasia after 2 years. METHODS: A prospective, single-center case series was performed with patients treated for postoperative LASIK ectasia. All eyes underwent accelerated corneal collagen cross-linking (CCL-Vario Crosslinking; Peschke Meditrade GmbH, Zurich, Switzerland) at 9 mW/cm(2) for 10 minutes. The main outcome measures were changes in uncorrected distance visual acuity, corrected distance visual acuity, central corneal thickness, corneal topography, and endothelial cell density. These parameters were assessed at baseline and at the 6-month and 1- and 2-year follow-up visit. RESULTS: The study enrolled 40 eyes of 24 patients (15 male and 9 female) with a mean age of 33.8 ± 7.5 years (range: 24 to 52 years) that attained at least 2 years of follow-up. The surgical procedure was uneventful in all cases. All eyes stabilized after treatment without any further signs of progression and no statistically significant changes in the mean uncorrected distance visual acuity (P = .649), corrected distance visual acuity (P = .616), mean keratometry (P =.837), steep keratometry (P = .956), ultrasonic pachymetry (P = .135), slit-scanning pachymetry (P = .276), and endothelial cell density (P = .523). In addition, 72.5% of the patients presented stable or gains of Snellen lines over time. CONCLUSIONS: Accelerated corneal collagen cross-linking seems to be safe and effective in halting postoperative LASIK ectasia progression after 2 years of follow-up. However, a longer follow-up period with a larger cohort is needed to validate these findings.

Optical quality in eyes implanted with aspheric and spherical intraocular lenses assessed by NIDEK OPD-Scan: a randomized, bilateral, clinical trial.

PURPOSE: To determine whether implantation of an intraocular lens (IOL) with an aspheric surface (Akreos AO, Bausch & Lomb Inc) results in reduced ocular aberrations (spherical aberration) and improved Strehl ratio and modulation transfer function (MTF) after cataract surgery. METHODS: In an intraindividual, randomized, double-masked, prospective study of 50 eyes (25 patients) with bilateral cataract, an IOL with modified anterior and posterior surfaces (Akreos AO) was implanted in one eye and a biconvex IOL with spherical surfaces (Akreos Fit, Bausch & Lomb Inc) implanted in the fellow eye. Ocular aberrations, Strehl ratio, and MTF curve with 4.5-, 5.0-, and 6.0-mm pupils were measured with a NIDEK OPD-Scan dynamic retinoscopy aberrometer 3 months after surgery. Uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively) were also measured. RESULTS: No statistically significant difference was noted between eyes in postoperative UDVA and CDVA at 1 month. At 3 months, the Akreos AO IOL group obtained statistically significant lower values of higher order and spherical aberrations with 4.5-, 5.0-, and 6.0-mm pupil diameters than the Akreos Fit IOL group (P<.05). The value of Strehl ratio was statistically significantly higher in eyes with the Akreos AO IOL for 4.5- and 6.0-mm pupils (P<.05). The MTF curve was better in the Akreos AO IOL group in 4.5-, 5.0-, and 6.0-mm pupils (P<.05). CONCLUSIONS: The aspheric Akreos AO IOL induced significantly less spherical aberration than the Akreos Fit IOL for 4.5-, 5.0-, and 6.0-mm pupils. Modulation transfer function and Strehl ratio were also better in eyes implanted with the Akreos AO IOL than the Akreos Fit.

Visual performance of an apodized diffractive multifocal intraocular lens with +3.00-d addition: 1-year follow-up.

PURPOSE: To determine whether implantation of a multifocal intraocular lens (IOL) with a lower addition (+3.00 diopters [D]) at the lens plane results in better intermediate visual acuity 1 year after surgery compared with a multifocal IOL with higher addition (+4.00 D). METHODS: This prospective, randomized, double-masked study included 80 eyes from 40 patients. Twenty patients were implanted bilaterally with the ReSTOR +3.00-D add IOL and 20 patients were implanted bilaterally with the ReSTOR +4.00-D add IOL. Primary outcome measures were distance, intermediate, and near visual acuity. Secondary outcomes were defocus curves, best reading distance, mesopic and photopic contrast sensitivity, quality of life, and spectacle independence. Monocular and binocular visual acuity were measured as uncorrected and corrected distance visual acuity at 4 m, uncorrected near and distance-corrected near visual acuity at 40 cm, and uncorrected intermediate visual acuity and distance-corrected intermediate visual acuity at 50, 60, and 70 cm. RESULTS: Twelve months postoperatively, no statistically significant difference between groups in distance and near visual acuity was noted. The ReSTOR +3.00-D add group performed better than the ReSTOR +4.00-D add group at all intermediate distances studied. The ReSTOR +4.00-D group chose a reading distance 8 cm closer than the +3.00-D group. Both groups performed similarly with respect to contrast sensitivity, quality of life, and spectacle independence rates. CONCLUSIONS: Patients implanted with a multifocal IOL with lower addition (ReSTOR +3.00 D) had better performance at intermediate distances compared with the ReSTOR +4.00-D add IOL with similar performance for distance and near visual acuity, contrast sensitivity, and quality of life.

Topography-guided (NIDEK customized aspheric treatment zone) photorefractive keratectomy with mitomycin C after penetrating keratoplasty for keratoconus: case report.

PURPOSE: To report topography-guided photorefractive keratectomy (PRK) with mitomycin C (MMC) after penetrating keratoplasty for keratoconus. METHODS: A 34-year-old woman with irregular astigmatism after penetrating keratoplasty in the right eye underwent PRK. Topography-guided surface ablation using the customized aspheric treatment zone ablation (CATz) was programmed for a 5.00-mm optical zone and an 8.50-mm transition zone. Mitomycin C was applied to corneal stroma for 20 seconds immediately after excimer laser ablation. RESULTS: Two months after surgery, the patient was very satisfied with the refractive outcome. Best spectacle-corrected visual acuity was 20/20 with a manifest refraction of -0.50 diopters. No haze formation was detected at 6-month follow-up. A significant improvement in the central 3 mm of the axial topography was noted. CONCLUSIONS: Topography-guided ablation using MMC may be a reasonable alternative for the management of refractive error after penetrating keratoplasty.

A longitudinal study of LASIK flap and stromal thickness with high-speed optical coherence tomography.

OBJECTIVE: To assess corneal anatomic changes after LASIK with a high-speed corneal and anterior segment optical coherence tomography (CAS-OCT) system. DESIGN: Cross-sectional observational study. PARTICIPANTS: Fifty-one eyes of 26 healthy persons undergoing LASIK. METHODS: The CAS-OCT prototype operated at a 1.3-mum wavelength and 2000 axial scans/second. The corneas were scanned with a flap profile pattern (horizontal line, 512 axial scans) and a flap map pattern (4 radials, 256 axial scans each). Both patterns are 8 mm long and are centered on the corneal vertex. LASIK flaps were created using either a mechanical microkeratome (Hansatome; Bausch & Lomb, Inc., Rochester, NY) or a femtosecond laser (Pulsion; IntraLase Corp., Irvine, CA). Intraoperative pachymetry was performed using a 50-MHz ultrasound probe. Three OCT scans were obtained on preoperative and post-LASIK visits up to 6 months. An automated algorithm was developed to process the OCT images and to calculate corneal, flap, and stromal bed thickness profiles and maps. The profiles and maps were divided into central (diameter, <2 mm), pericentral (2-5 mm), and transitional (5-7 mm) zones for analysis. MAIN OUTCOME MEASURES: Corneal, flap, and stromal bed thicknesses as determined by OCT and ultrasound pachymetry. RESULTS: The flap interface was best detected in the pericentral zone. One week after surgery, the repeatability of OCT flap and stromal bed thickness measurement was 2 to 7 microm by pooled standard deviation for zones inside a 5-mm diameter. The central flap thickness in 24 Hansatome eyes with a 180-microm setting was 143+/-14 microm by OCT and 131+/-17 microm by ultrasound. In the 8 IntraLase cases with a 120-microm setting, it was 156+/-11 microm by OCT and 160+/-19 microm by ultrasound. Eyes with other settings also were analyzed. There were small systematic changes in flap thickness up to 1 week and bed thickness up to 3 months. CONCLUSIONS: We have developed a method for using high-speed OCT to measure LASIK flap thickness after surgery. The measurement is noncontact, rapid, and repeatable. Profile and map measurements provide more information than point measurements previously demonstrated. This could be valuable for planning LASIK enhancement and characterizing microkeratome performance.

Corneal haze following PRK with mitomycin C as a retreatment versus prophylactic use in the contralateral eye.

PURPOSE: To report photorefractive keratectomy (PRK) treated with mitomycin C (MMC) for previous corneal haze in one eye and PRK with MMC to prevent corneal haze formation in the fellow eye. METHODS: A 40-year-old woman underwent PRK with MMC to treat previous corneal haze (secondary to previous PRK without MMC) for residual refractive error of +0.50 +0.25 x 165 in the left eye and PRK with MMC to prevent corneal haze in the right eye. RESULTS: Postoperative slit-lamp examination revealed no haze in the right eye, but continued mild haze in the left eye. CONCLUSIONS: Treatment with PRK and MMC for previous corneal haze is not as effective as primary PRK with MMC in preventing postoperative corneal haze formation.

Surface wave elastometry of the cornea in porcine and human donor eyes.

PURPOSE: To introduce a nondestructive technique for characterization of corneal stiffness, determine measurement precision, and investigate comparative stiffness values along central, radial, and circumferential vectors in porcine corneas. The effects of epithelial debridement, relaxing incisions, and crosslink-mediated stiffening on surface wave velocity are also studied. METHODS: A handheld prototype system was used to measure ultrasound surface wave propagation time between two fixed-distance transducers along a ten-position map. Repeatability was assessed with replicate measurements in 6 porcine corneas. In 12 porcine globes with controlled intraocular pressure (IOP), serial measurements were performed before and after epithelial removal, then after 250- and 750-microm-deep relaxing incisions. In human globes with constant intravitreal pressure, central wave velocity and transcorneal IOP measurements were compared before and after collagen cross-linking. RESULTS: Measurement repeatability across all regions was between 2.2% and 8.1%. Epithelial removal resulted in increases in measured stiffness in 67% of eyes, but statistical power was insufficient to detect a systematic change. Wave velocity across a central incision decreased significantly after 250-microm keratotomy (P < .001), but did not undergo a significant further decrease with deeper keratotomy. Meridional stiffness changes consistent with coupling effects were detected after keratotomy. Surface wave velocity and transcorneal IOP measurements increased markedly after collagen cross-linking despite maintenance of a constant IOP. CONCLUSIONS: Handheld corneal elastometry provides a repeatable measure of regional stiffness changes after relaxing incisions and collagen cross-linking in in vitro experiments. Surface wave elastometry allows focal assessment of corneal biomechanical properties that are relevant in refractive surgery, ectatic disease, and glaucoma.

Wavefront analysis comparison of LASIK outcomes with the femtosecond laser and mechanical microkeratomes.

PURPOSE: To evaluate differences related to ocular aberrations after customized LASIK for myopia using three different microkeratomes. METHODS: Charts of 410 patients who underwent customized LASIK with the Alcon LADARVision4000 excimer laser were reviewed. Patients were stratified according to the device used to create the flap: Moria M2 microkeratome, Bausch & Lomb Hansatome microkeratome, or IntraLase laser. The difference between the wavefront pre- and postoperative value received a positive or a negative sign if the change occurred toward or away from zero, respectively, and it was compared to preoperative minus postoperative manifest refraction spherical equivalent (MRSE). RESULTS: Patients showed increase in the aberration level after LASIK with the three devices used in this study. IntraLase spherical aberration change tended to be better than mechanical microkeratomes for higher MRSE values (IntraLase compared to Hansatome, P < or = .023 for MRSE values > or = 4.00 diopters [D]; IntraLase compared to Moria, P < or = .015 for MRSE values > or = 2.00 D). For total aberrations, the improvement values for IntraLase tended to be higher than those for Moria (IntraLase compared to Moria, P < or = .021 for MRSE values > or = 3.00 D). For total higher order aberrations, IntraLase values tended to be better than Moria and Hansatome microkeratomes (IntraLase compared to Hansatome, P < or = .047 for MRSE values between 3.00 and 8.00 D; IntraLase compared with Moria, P < or = .002 for MRSE values > or = 2.00 D). Change in coma root-mean-square was similar for the three groups. CONCLUSIONS: The findings suggest the femtosecond laser provides a better platform for LASIK than the commonly used microkeratomes analyzed in this study.

Femtosecond laser and microkeratome corneal flaps: comparison of stromal wound healing and inflammation.

PURPOSE: To examine early postoperative wound healing in rabbit corneas that had LASIK flaps formed with three different models (15 KHz, 30 KhZ, and 60 KHz) of a femtosecond laser compared with flaps formed with a microkeratome. METHODS: Thirty-nine rabbit eyes were randomized to receive either no surgery or corneal flaps formed with one of the lasers or the microkeratome. Sixteen eyes also had lamellar cuts with no side cuts with the 30 KHz laser. Animals were sacrificed and corneas processed as frozen sections or fixed for transmission electron microscopy. Frozen sections were evaluated with the TUNEL assay to detect apoptosis, immunocytochemistry for Ki67 to detect cell mitosis, and immunocytochemistry for CD11b to detect mononuclear cells. RESULTS: Rabbit corneas that had flaps formed with the 15 KHz laser had significantly more stromal cell death, greater stromal cell proliferation, and greater monocyte influx in the central and peripheral comea at 24 hours after surgery than corneas that had flaps formed with the 30 KHz or 60 KHz laser or the microkeratome. Results of the 60 KHz laser and microkeratome were not significantly different for any of the parameters at 24 hours, except for mitotic stromal cells at the flap margin. Transmission electron microscopy revealed that the primary mode of stromal cell death at 24 hours after laser ablation was necrosis. CONCLUSIONS: Stromal cell necrosis associated with femtosecond laser flap formation likely contributes to greater inflammation after LASIK performed with the femtosecond laser, especially with higher energy levels that result in greater keratocyte cell death.

Gene therapy in the cornea.

Technological advances in the field of gene therapy has prompted more than three hundred phase I and phase II gene-based clinical trials for the treatment of cancer, AIDS, macular degeneration, cardiovascular, and other monogenic diseases. Besides treating diseases, gene transfer technology has been utilized for the development of preventive and therapeutic vaccines for malaria, tuberculosis, hepatitis A, B and C viruses, AIDS, and influenza. The potential therapeutic applications of gene transfer technology are enormous. The cornea is an excellent candidate for gene therapy because of its accessibility and immune-privileged nature. In the last two decades, various viral vectors, such as adeno, adeno-associated, retro, lenti, and herpes simplex, as well as non-viral methods, were examined for introducing DNA into corneal cells in vitro, in vivo and ex vivo. Most of these studies used fluorescent or non-fluorescent marker genes to track the level and duration of transgene expression in corneal cells. However, limited studies were directed to evaluate prospects of gene-based interventions for corneal diseases or disorders such as allograft rejection, laser-induced post-operative haze, herpes simplex keratitis, and wound healing in animal models. We will review the successes and obstacles impeding gene therapy approaches used for delivering genes into the cornea.

Wavefront-guided ablation: evidence for efficacy compared to traditional ablation.

PURPOSE: To provide an evidence-based overview of wavefront-guided refractive surgery outcomes, benefits, and limitations. DESIGN: Literature review. METHODS: Review of FDA study reports and indexed, peer-reviewed literature. RESULTS: More than 400 reports investigating wavefront applications in refractive surgery exist, but studies comparing the outcomes of wavefront-guided treatment with conventional treatment are few in number. Available studies do not overwhelmingly demonstrate superior visual results attributable to a wavefront-guided approach. CONCLUSIONS: While wavefront-guided refractive surgery provides excellent results, evidence is limited that it outperforms conventional laser in situ keratomileusis that incorporates broad ablation zones, smoothing to the periphery, eye-trackers, and other technological refinements. However, it is evident that wavefront-customized ablation holds a promising future and merits ongoing investigation.

Precision of higher order aberration repeatability with NIDEK OPD-scan retinoscopic aberrometry.

PURPOSE: To evaluate repeatability of the total high order aberrations with a retinoscopic wavefront sensor. METHODS: This prospective case series analyzed 12 eyes from 6 patients who underwent wavefront measurement using retinoscopic aberrometry with the NIDEK Optical Path Difference Scan (OPD-Scan). Four consecutive wavefront measurements of each eye were taken by two trained examiners for 5.8+/-0.8-mm and 8.2+/-0.6-mm pupils (P=.002, Wilcoxon test). Total high order aberrations out to the eighth order were assessed including third order coma, third order trefoil, fourth order quadrafoil, fourth order secondary astigmatism, and fourth order spherical aberrations. Differences between measurements of all of the variables were analyzed. A P value <.05 was considered statistically significant. RESULTS: Repeatability analysis of the root-mean-square of total higher order aberrations, coma, trefoil, quadrafoil, secondary astigmatism, and spherical aberrations for both dilated and nondilated pupils did not show a statistically significant difference among all repeated measurements, except for trefoil and secondary astigmatism (analysis of variance and the Friedman test). The repeatability of total higher order aberrations was 0.15 microm for nondilated pupils and 0.18 microm for dilated pupils. Except for trefoil measurements, all high order aberrations showed reproducibility >0.15 microm when Zernike coefficients were analyzed individually. CONCLUSIONS: The NIDEK OPD-Scan aberrometer measures total higher order astigmatism and most individual aberrations with acceptable repeatability. However, measurement of trefoil with this instrument is less repeatable.

Effect of prophylactic and therapeutic mitomycin C on corneal apoptosis, cellular proliferation, haze, and long-term keratocyte density in rabbits.

PURPOSE: To determine the mechanism through which topical mitomycin C prevents and treats corneal haze after photorefractive keratectomy (PRK) and to examine the effects of dosage and duration of exposure. METHODS: In 224 New Zealand rabbits, -9.0 diopter PRK with mitomycin C or balanced salt solution was performed. Haze level was graded at the slit-lamp. Rabbits were sacrificed at 4 hours, 24 hours, 4 weeks, or 6 months after surgery and immunohistochemistry was performed with TUNEL assay, Ki67, and alpha-SMA. RESULTS: TUNEL-positive apoptotic cells marginally increased in all mitomycin C groups whereas Ki67-positive mitotic cells decreased significantly following mitomycin C application. A greater decrease in myofibroblasts was noted with prophylactic mitomycin C treatment than therapeutic mitomycin C treatment. There was, however, an anterior stromal acellular zone (approximately 20% of the total stroma) in eyes treated with mitomycin C, which persisted to the maximum follow-up of 6 months. CONCLUSIONS: Mitomycin C treatment induces apoptosis of keratocytes and myofibroblasts, but the predominate effect in inhibiting or treating haze appears to be at the level of blocked replication of keratocytes or other progenitor cells of myofibroblasts. Treatment with 0.002% mitomycin C for 12 seconds to 1 minute appears to be just as effective as higher concentrations for longer duration in the rabbit model. However, a persistent decrease in keratocyte density in the anterior stroma could be a warning sign for future complications and treatment should be reserved for patients with significant risk of developing haze after PRK.

Femtosecond Laser-Assisted LASIK Flap Complications.

PURPOSE: To discuss intraoperative and postoperative femtosecond laser-assisted LASIK flap complications and their management. METHODS: Review of published literature. RESULTS: Flap creation is a critical step in LASIK. The femtosecond laser has improved the overall predictability and safety of the lamellar incision, but complications can still occur during or after flap creation. Although many complications (eg, epithelial ingrowth and flap striae) were reduced with the femtosecond laser application, other specific complications have emerged, such as vertical gas breakthrough, opaque bubble layer, and transient light-sensitivity syndrome. CONCLUSIONS: The application of femtosecond laser technology to LASIK flap creation has increased greatly since its introduction. These lasers have improved the safety and predictability of the lamellar incision step. The majority of the femtosecond laser-assisted flap complications can be well managed without significant effects on refractive outcomes.

Corneal Collagen Cross-linking in Advanced Keratoconus: A 4-Year Follow-up Study.

PURPOSE: To analyze the safety and efficacy of standard corneal collagen cross-linking (CXL) in advanced cases of progressive keratoconus after 4 years of follow-up. METHODS: A retrospective case series of patients with advanced progressive keratoconus (stages 3 and 4 of Amsler-Krumeich classification) underwent standard CXL treatment. The parameters examined were changes in uncorrected visual acuity (UDVA), corrected visual acuity (CDVA), keratometry values (mean, flat, steep, and apical), pachymetry, and endothelial cell count at the baseline and at 12, 24, and 48 months postoperatively. RESULTS: Forty eyes of 40 patients were enrolled in the study. The mean patient age was 22.5 years (range: 15 to 37 years). Both mean UDVA and CDVA remained stable during the time points; no statistically significant change was noted. Although a slight reduction was observed in all keratometric readings, a statistically significant reduction was only reached in the apical keratometry (P = .037) at 4 years after CXL. A significant reduction in the corneal thickness was also found (ultrasonic: 388 ± 49 to 379 ± 48 µm; slit-scanning: 362 ± 48 to 353 ± 51 µm); however, this change was likely not clinically meaningful. Endothelial cell count was not significantly different at the end of the study. Treatment failure or progression was noted in two patients (5%) over the follow-up period. CONCLUSIONS: Standard CXL treatment was safe and able to stabilize both visual acuity and topographic parameters at 4 years of follow-up in eyes with advanced keratoconus. [J Refract Surg. 2016;32(7):459-464.].

Wavefront analysis in normal refractive surgery candidates.

PURPOSE: To quantify the higher order aberrations of refractive surgery candidates and compare the wavefront-determined refractions with manifest refractions refined with a +/- 0.25 Jackson cross cylinder. METHODS: Results of 226 consecutive patients (418 eyes) were analyzed with the WaveScan WavePrint system (VISX, Santa Clara, Calif). Only patients with normal eyes without previous surgery were included. RESULTS: The mean spherical equivalent refraction determined with wavefront analysis was -3.40 +/- 3.14 diopters (D) (range: -10.72 to +5.41 D). The largest amount of higher order aberrations was detected with : a 6-mm pupil diameter (coma 0.14 +/- 0.08 microm; trefoil 0.10 +/- 0.07 microm; spherical aberrations 0.09 +/- 0.07 microm). The mean root-mean-square of higher order aberrations and total aberrations were 0.23 +/- 0.11 microm and 4.00 +/- 2.45 microm, respectively. No statistically significant correlation was noted between higher order aberrations and gender (P = 0.7) or between higher order aberration and refractive level (P > .59). The mean differences in spherical equivalent refraction, sphere, and cylinder between WaveScan measurements and manifest refraction were 0.36 +/- 0.41 D, 0.40 +/- 0.44 D, and 0.28 +/- 0.32 D, respectively. CONCLUSIONS: This study provides reference values for higher order aberrations in normal refractive surgery candidates. Wavefront analysis also proved to be a valuable tool for objectively measuring preoperative refractive error.

Wound healing in the cornea: a review of refractive surgery complications and new prospects for therapy.

PURPOSE: The corneal wound healing response is of particular relevance for refractive surgical procedures since it is a major determinant of efficacy and safety. The purpose of this review is to provide an overview of the healing response in refractive surgery procedures. METHODS: Literature review. RESULTS: LASIK and PRK are the most common refractive procedures; however, alternative techniques, including LASEK, PRK with mitomycin C, and Epi-LASIK, have been developed in an attempt to overcome common complications. Clinical outcomes and a number of common complications are directly related to the healing process and the unpredictable nature of the associated corneal cellular response. These complications include overcorrection, undercorrection, regression, corneal stroma opacification, and many other side effects that have their roots in the biologic response to surgery. The corneal epithelium, stroma, nerves, inflammatory cells, and lacrimal glands are the main tissues and organs involved in the wound healing response to corneal surgical procedures. Complex cellular interactions mediated by cytokines and growth factors occur among the cells of the cornea, resulting in a highly variable biologic response. Among the best characterized processes are keratocyte apoptosis, keratocyte necrosis, keratocyte proliferation, migration of inflammatory cells, and myofibroblast generation. These cellular interactions are involved in extracellular matrix reorganization, stromal remodeling, wound contraction, and several other responses to surgical injury. CONCLUSIONS: A better understanding of the complete cascade of events involved in the corneal wound healing process and anomalies that lead to complications is critical to improve the efficacy and safety of refractive surgical procedures. Recent advances in understanding the biologic and molecular processes that contribute to the healing response bring hope that safe and effective pharmacologic modulators of the corneal wound healing response may soon be developed.

Thygeson's superficial punctate keratitis recurrence after laser in situ keratomileusis.

PURPOSE: To report a case of recurrent Thygeson's superficial punctate keratitis (SPK) in a patient submitted to photorefractive keratectomy (PRK) in one eye and laser in situ keratomileusis (LASIK) in the fellow eye. DESIGN: Observational case report. METHODS: A 32-year-old woman was diagnosed with Thygeson's SPK 5 years before undergoing PRK on the right eye and LASIK on the left eye to correct -3.00 + 1.50 x 20 and -3.75 sph, respectively. RESULTS: The patient presented with recurrence of Thygeson's SPK in the left eye 10 months after the LASIK procedure and no recurrence on the right eye, which was treated with PRK. CONCLUSIONS: This case report suggests that PRK may be a better option than LASIK in patients with ocular history of Thygeson's SPK. However, no strong conclusion can be established until further studies confirm the hypothesis of a lower recurrence rate of Thygeson's SPK following PRK compared with LASIK.

Pupil size in refractive surgery candidates.

PURPOSE: To assess pupil size measurements obtained under scotopic and mesopic conditions with the Procyon pupillometer and under photopic conditions with the Humphrey videokeratographer. METHODS: The pupil sizes of 96 candidates for refractive surgery (192 eyes) were measured with the Procyon pupillometer PS2000 SA and the Humphrey Atlas 992 corneal topographer. Anisocoria and pupillary unrest were analyzed according to gender (two groups: 51 females and 45 males), age (five groups: 20 to 30 yr, 31 to 40 yr, 41 to 50 yr, 51 to 60 yr, older than 60 yr) and level of refraction (five groups: >-6.00 D SE, -6.00 to -3.00 D SE, -3.00 to 0 D SE, 0 to +2.50 D SE, +2.50 to +5.00 D SE). RESULTS: The median value of pupil diameter measured with the Procyon pupillometer at the scotopic (0.04 lux), mesopic-low (0.4 lux), and mesopic-high (4 lux) levels of illumination were 6.54+/-0.88 mm; 5.62+/-0.95 mm, and 4.09+/-0.76 mm, respectively. The median pupil size with the Humphrey topographer was 3.65+/-0.62 mm. Pupillary unrest was highest at the mesopic-high level of illumination, with a median value of 0.31+/-0.34 mm. Median pupil size measured with both instruments at all light levels dropped significantly after the fifth decade of life (P<.05, ANOVA). CONCLUSIONS: The Procyon pupillometer and Humphrey videokeratographer revealed an inverse correlation between the pupil size and the age, but no relationship with gender or level of refraction. The Procyon pupillometer provides an objective method for measuring pupil size at controlled light levels with a permanent printed record.

Bilateral marginal sterile infiltrates and diffuse lamellar keratitis after laser in situ keratomileusis.

PURPOSE: To report cases of acute bilateral catarrhal infiltrates in the early postoperative period after laser in situ keratomileusis (LASIK). METHODS: Retrospective review of both eyes of two patients. RESULTS: Two patients developed acute bilateral, marginal, catarrhal infiltrates in the early postoperative period after LASIK. Both patients had moderate to severe chronic meibomian gland dysfunction preoperatively. One patient (both eyes) developed grade 3 diffuse lamellar keratitis (DLK) that required both flaps to be lifted for irrigation and cleaning on postoperative day 5. Fungal and bacterial cultures were negative in both eyes of both patients. The condition resolved with intensive topical corticosteroids and fortified antibiotics. Regression of refractive error and the need for enhancement was encountered in all eyes. There was mild recurrence in one eye of each patient with pretreatment with topical corticosteroids prior to enhancement. CONCLUSIONS: Endogenous factors such as chronic blepharitis and meibomian gland dysfunction may trigger inflammation resulting in sporadic cases of catarrhal infiltrates after LASIK. These patients may have chronic inflammatory milieus that can trigger sporadic cases of catarrhal infiltrates after LASIK, with accompanying diffuse lamellar keratitis.