Decision taking in corneal refractive surgery.

A 27-year-old woman who wants to get rid of contact lenses and spectacles was seen at our clinic. She had strabismus surgery as a child and was patched for the right eye but now shows mild nondisturbing exophoria. Infrequently, she likes to box in the sports school. Her corrected distance visual acuity at presentation in the right eye was 20/16 with -3.75 -0.75 × 50 and in the left eye 20/16 with -3.75 -1.25 × 142. Her cycloplegic refraction in the right eye was -3.75 -0.75 × 44 and in the left eye was -3.25 -1.25 × 147. The left eye is the dominant eye. The tear break-up time was 8 seconds in both eyes, and the Schirmer tear test was 7 to 10 mm in right and left eyes, respectively. Pupil sizes under mesopic conditions were 6.62 mm and 6.68 mm. The anterior chamber depth (ACD) (measured from the epithelium) in the right eye was 3.89 mm and in the left eye was 3.87 mm. The corneal thickness was 503 µm and 493 µm of the right and left eye, respectively. Corneal endothelial cell density was on average 2700 cells/mm2 for both eyes. Slitlamp biomicroscopy showed clear corneas and a normal flat iris configuration. Supplemental Figures 1 to 4 (available at http://links.lww.com/JRS/A818, http://links.lww.com/JRS/A819, http://links.lww.com/JRS/A820, and http://links.lww.com/JRS/A821) show the corneal topography and Belin-Ambrósio deviation (BAD) maps at presentation of the right eye and left eye, respectively. Would you consider this patient a candidate for corneal refractive surgery (eg, laser-assisted subepithelial keratectomy, laser in situ keratomileusis [LASIK], or small-incision lenticule extraction [SMILE] procedure)? Has your opinion changed given the recent opinion of the U.S. Food and Drug Administration (FDA) regarding LASIK?1 The patient herself is slightly favoring an implantation of a phakic intraocular lens (pIOL), as she prefers something reversible. Would you implant a pIOL, and which type of IOL, for this level of myopia? What is your diagnosis or are additional diagnostic methodologies needed to establish a diagnosis? What is your treatment advice for this patient? REFERENCES 1. U.S. Food and Drug Administration, HHS. Laser-assisted in situ keratomileusis (LASIK) lasers-patient labeling recommendations; draft guidance for industry and food and drug administration staff; availability. July 28, 2022, Federal Register; 87 FR 45334. Available at: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/laser-assisted-situ-keratomileusis-lasik-lasers-patient-labeling-recommendations Accessed January 25, 2023.

Anterior-segment optical coherence tomography investigation of corneal deturgescence and epithelial remodeling after DSAEK.

PURPOSE: The aim of this study was to evaluate via Fourier-domain anterior-segment optical coherence tomography 3-dimensional corneal, epithelial, and graft thickness changes after Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Sixteen eyes were investigated preoperatively and up to 6 months postoperatively for preoperative and postoperative central corneal thickness (CCT), minimum corneal thickness, central graft thickness (CGT), and for epithelial topographic thickness variability. An age-matched and gender-matched control group of 32 healthy eyes was used for comparison. RESULTS: In the DSAEK group, the preoperative CCT was 582.32 ± 45.24 (550-615) µm. One-month postoperatively, the CCT was 736.26 ± 34.52 (713-771) µm, and the CGT was 210.42 ± 34.52 (145-243) µm. Three months postoperatively, the CCT was 641.39 ± 38.75 (569-684) µm, and the CGT was 171.23 ± 27.54 (119-185) µm. The preoperative center epithelial thickness was 55.74 ± 9.29 (45-74) µm, the minimum was 32.53 ± 14.30 (13-53) µm, the maximum was 76.00 ± 11.32 (64-105) µm, and the topographic thickness variability was 10.84 ± 4.09 (5.90-18.80) µm. Three months postoperatively, the center epithelial thickness was 47.21 ± 5.45 (43-56) µm, the minimum was 35.11 ± 4.70 (30-41) µm, the maximum was 58.11 ± 6.51 (49-65) µm, and the topographic variability was 4.77 ± 1.48 (2.90-6.50) µm. The average differences were -8.53, +4.53, and -17.89 µm for the center, minimum, and maximum (P < 0.001, <0.001, and <0.001). Similar results were obtained 3 and 6 months postoperatively. CONCLUSIONS: We present a near-term postoperative investigation of the corneal and epithelial thickness changes after DSAEK for bullous keratopathy, by in vivo, clinical anterior-segment optical coherence tomography. Epithelial thickness recovery and normalization and corneal deturgescence were noted as early as in the first postoperative month.

Influence of corneal cross-linking for keratoconus on several objective parameters of dry eye.

PURPOSE: To evaluate the potential influence of corneal cross-linking (CXL) with ultraviolet-A light and riboflavin in keratoconic eyes on several objective parameters of dry eye syndrome. METHODS: This prospective single center study included 30 consecutive eyes of 16 patients that underwent CXL with riboflavin and ultraviolet-A treatment (epithelial removal, 30 minutes soaking with riboflavin, 30 minutes of illumination with 365 nm, 3 mW/cm(2), 5 cm distance). Several dry eye syndrome parameters were evaluated preoperatively and 3 and 6 months after the procedure: intra-individual comparison of fluorescein and Rose bengal staining, height of tear film meniscus, and tear film break-up time. RESULTS: Pathologic staining (more than 10 point-shaped areas or diffuse staining) with fluorescein was evident before CXL in 1 eye, 3 months after CXL in 1 eye, and 6 months after CXL in 1 eye. Rose bengal staining 3 and 6 months postoperatively was comparable to preoperative staining. Tear film height was reduced in 2 eyes before CXL and in 4 eyes 3 months postoperatively, and was normal in all eyes after 6 months. The number of eyes with reduced tear film break-up time was not significantly changed. CONCLUSIONS: CXL had no significant impact on several parameters of dry eye syndrome 3 and 6 months postoperatively.

FS200 femtosecond laser LASIK flap digital analysis parameter evaluation: comparing two different types of patient interface applanation cones.

PURPOSE: To evaluate the safety and efficacy of a novel LASIK flap patient interface (PI) cone with our reported digital analysis and compare for potential differences with the standard metal and glass PI in flap parameters when used with the Alcon/WaveLight FS200 femtosecond laser. PATIENTS AND METHODS: Thirty-six consecutive LASIK patients (72 eyes) subjected to a bilateral femtosecond assisted LASIK procedure with the novel clear cone PI FS200 1505 were examined for flap diameter and flap thickness over the entire flap area via digital analysis performed on intraoperation image (flap diameter) and anterior-segment optical coherence tomography image (flap thickness). This group was compared with an age- and procedure-matched group B from our practice, in which the standard metal and glass PI was employed. RESULTS: Horizontal flap diameter for group A (clear cone) was 7.87 mm ± 0.02 mm (range 7.89-7.84 mm) for 8.00 mm programmed, whereas for group B (metal and glass cone) was 7.85 mm ± 0.04 mm (range 7.93-7.80 mm). Likewise, along the vertical line, flap diameter for group A was 7.84 mm ± 0.02 mm (range 7.85-7.80 mm) and for group B was 7.83 mm ± 0.03 mm (range 7.87-7.80 mm). Central flap thickness for group A was 113.29 µm (±1.19 µm) for 110 µm planned, 122.1 µm (±2.10 µm) for 120 µm planned, and 133.50 µm (±0.71 µm) for 130 µm planned. Group B central flap thickness was, accordingly, 112.8 µm (±1.25 µm), 122.4 µm (±2.15 µm), and 132.50 µm (±0.90 µm). The data evaluated (paired group comparisons) between group A and group B did not show statistically significant differences. CONCLUSION: This study indicates that two PIs in use with the FS200 femtosecond laser are safe and have highly reproducible and accurate flap parameter results, such as achieved diameter and flap thickness. The paired group comparisons between the two PIs' respective data do not show statistically significant differences.

Anterior segment optical coherence tomography: assisted topographic corneal epithelial thickness distribution imaging of a keratoconus patient.

PURPOSE: To evaluate safety, efficacy and ease of measurement of epithelial thickness in a keratoconic patient based on anterior segment optical coherence tomography (AS-OCT). METHODS: A 25-year-old male patient, previously diagnosed with keratoconus, with highly asymmetric manifestation among the two eyes, was subjected to AS-OCT corneal epithelial imaging. We investigated epithelial thickness and epithelial topographic thickness distribution. RESULTS: Mean epithelial thickness was 51.97 ± 0.70 for the less affected right eye (OD), and 55.65 ± 1.22 for the more affected left eye (OS). Topographic epithelial thickness variability for the OD was 1.53 ± 0.21 µm, while for the OS it was 9.80 ± 0.41 µm. CONCLUSIONS: This case further supports our previous findings with high-frequency ultrasound measurements of the increase in overall epithelial thickness in keratoconic eyes in comparison with normal eyes. AS-OCT further offers ease of use and possibly higher predictability of measurement. This case report, based on AS-OCT imaging, verifies increased overall epithelial thickness in keratoconic eyes, as introduced by a previous study [Kanellopoulos et al.: Clin Ophthalmol 2012;6:789-800], based on high-frequency scanning ultrasound biomicroscopy imaging.

Essential opaque bubble layer elimination with novel LASIK flap settings in the FS200 Femtosecond Laser.

BACKGROUND: The purpose of this study is to evaluate the extent and incidence of opaque bubble layer (OBL) using laser-assisted in situ keratomileusis (LASIK) flaps created with the Alcon/WaveLight® FS200 femtosecond laser as a result of a recent change in flap programming parameters aiming to reduce further the incidence and extent of OBL. METHODS: Intraoperative digital images of flaps from 36 consecutive patients (72 eyes) subjected to bilateral femtosecond-assisted LASIK were analyzed using a proprietary computerized technique. The incidence and extent of OBL was measured and reported as a percentage of the entire flap area. Flap creation was performed with a 1.7 mm wide canal, implemented as an updated design intended to reduce the extent of OBL (group A). The same OBL parameters were investigated and compared in an age-matched and procedure-matched patients in whom the previous standard setting of a 1.3 mm wide canal was implemented (group B). RESULTS: In group A, the average extent of OBL was 3.69% of the flap area (range 0%-11.34%). In group B, the respective values were 6.06% (range 0%-20.24%). We found the difference to be statistically significant (one-tailed P = 0.00452). CONCLUSION: This study suggests that there is a significant reduction in the incidence and extent of OBL when novel LASIK flap ventilation canal parameters of width and spot line separation are used.

Three-dimensional LASIK flap thickness variability: topographic central, paracentral and peripheral assessment, in flaps created by a mechanical microkeratome (M2) and two different femtosecond lasers (FS60 and FS200).

PURPOSE: To evaluate programmed versus achieved laser-assisted in situ keratomileusis (LASIK) flap central thickness and investigate topographic flap thickness variability, as well as the effect of potential epithelial remodeling interference on flap thickness variability. PATIENTS AND METHODS: Flap thickness was investigated in 110 eyes that had had bilateral myopic LASIK several years ago (average 4.5 ± 2.7 years; range 2-7 years). Three age-matched study groups were formed, based on the method of primary flap creation: Group A (flaps made by the Moria Surgical M2 microkeratome [Antony, France]), Group B (flaps made by the Abbott Medical Optics IntraLase™ FS60 femtosecond laser [Santa Ana, CA, USA]), and Group C (flaps made by the Alcon WaveLight(®) FS200 femtosecond laser [Fort Worth, TX, USA]). Whole-cornea topographic maps of flap and epithelial thickness were obtained by scanning high-frequency ultrasound biomicroscopy. On each eye, topographic flap and epithelial thickness variability was computed by the standard deviation of thickness corresponding to 21 equally spaced points over the entire corneal area imaged. RESULTS: The average central flap thickness for each group was 138.33 ± 12.38 µm (mean ± standard deviation) in Group A, 128.46 ± 5.72 µm in Group B, and 122.00 ± 5.64 µm in Group C. Topographic flap thickness variability was 9.73 ± 4.93 µm for Group A, 8.48 ± 4.23 µm for Group B, and 4.84 ± 1.88 µm for Group C. The smaller topographic flap thickness variability of Group C (FS200) was statistically significant compared with that of Group A (M2) (P = 0.004), indicating improved topographic flap thickness consistency - that is, improved precision - over the entire flap area affected. CONCLUSIONS: The two femtosecond lasers produced a smaller flap thickness and reduced variability than the mechanical microkeratome. In addition, our study suggests that there may be a significant difference in topographic flap thickness variability between the results achieved by the two femtosecond lasers examined.

Post intrastromal corneal ring segments insertion complicated by Candida parapsilosis keratitis.

This case report describes the clinical and histopathologic features, including molecular confirmation, of fungal keratitis after intrastromal corneal ring segments placement for keratoconus. A 52-year-old woman underwent insertion of Intacs(®) corneal implants for treatment of keratoconus. Extrusion of the implants was noted 5 months post insertion and replaced. Three months later, monocular infiltrates and an epithelial defect were observed. The Intacs were removed and the infiltrates were treated with ofloxacin and prednisolone acetate. Microbial cultures and stains were negative. The patient demonstrated flares and exacerbation one month later. Mycoplasma and/or fungus were suspected and treated without improvement. Therapeutic keratoplasty was performed 10 months following initial placement of the corneal ring implants. The keratectomy specimen was analyzed by light microscopy and a panfungal polymerase chain reaction assay. A histopathologic diagnosis of Candida parapsilosis keratitis was made and confirmed by polymerase chain reaction. One year postoperatively, a systemic workup of the patient was done with no signs of recurrence. This rare report of fungal keratitis following Intacs insertion is the first reported case of C. parapsilosis complicating Intacs implantation.

Long-term bladeless LASIK outcomes with the FS200 Femtosecond and EX500 Excimer Laser workstation: the Refractive Suite.

PURPOSE: The evaluation of the safety, efficacy, and long-term stability of LASIK procedures utilizing novel platform comprising a femtosecond and excimer laser and multiple networked diagnostics. SETTING: Private clinical ophthalmology practice. PATIENTS AND METHODS: In consecutive cases of myopic LASIK procedure with a novel refractive platform (FS200 Femtosecond and EX500 Excimer Laser), 190 eyes (from 109 different patients) were evaluated pre- and postoperatively for the following parameters: refractive error, best corrected distance visual acuity, uncorrected distance visual acuity, topography (Placido-disc based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. RESULTS: The change from pre- to postoperative mean refractive error was from -5.29 ± 2.39 diopters (D) (range -8.0 to -0.50 D) to -0.27 ± 0.09 D at the 3-month visit, -0.27 ± 0.10 D at the 6-month visit, and -0.39 ± 0.08 D at the 1-year visit. The change from pre- to postoperative refractive astigmatism was -1.07 ± 0.91 D (range -4.25 to 0 D) to -0.14 ± 0.04 D at 3 months, -0.15 ± 0.04 at 6 months, and -0.16 ± 0.04 at the 1-year visit. The proportion of the eyes with postoperative astigmatism within 0.5 D ranged between 95.6% and 99%. The proportion of eyes achieving uncorrected distance visual acuity of 1.0 (decimal) was 93.0%. CONCLUSION: The myopic LASIK clinical results with the FS200 Femtosecond Laser and EX500 Excimer Laser showed outstanding efficacy, great safety, and long-term stability.

Introduction of quantitative and qualitative cornea optical coherence tomography findings induced by collagen cross-linking for keratoconus: a novel effect measurement benchmark.

PURPOSE: To introduce a novel, noninvasive technique to determine the depth and extent of anterior corneal stroma changes induced by collagen cross-linking (CXL) using quantitative analysis of high-resolution anterior-segment optical coherence tomography (OCT) post-operative images. SETTING: Private clinical ophthalmology practice. PATIENTS AND METHODS: Two groups of corneal cross-sectional images obtained with the OptoVue RTVue anterior-segment OCT system were studied: group A (control) consisted of unoperated, healthy corneas, with the exception of possible refractive errors. The second group consisted of keratoconic corneas with CXL that were previously operated on. The two groups were investigated for possible quantitative evidence of changes induced by the CXL, and specifically, the depth, horizontal extent, as well as the cross-sectional area of intrastromal hyper-reflective areas (defined in our study as the area consisting of pixels with luminosity greater than the mean +2 × standard deviation of the entire stromal cross section) within the corneal stroma. RESULTS: In all images of the second group (keratoconus patients treated with CXL) there was evidence of intrastromal hyper-reflective areas. The hyper-reflective areas ranged from 0.2% to 8.8% of the cross-sectional area (mean ± standard deviation; 3.46% ± 1.92%). The extent of the horizontal hyper-reflective area ranged from 4.42% to 99.2% (56.2% ± 23.35%) of the cornea image, while the axial extent (the vertical extent in the image) ranged from 40.00% to 86.67% (70.98% ± 7.85%). There was significant statistical difference (P < 0.02) in these values compared to the control group, in which, by application of the same criteria, the same hyper-reflective area (owing to signal noise) ranged from 0.00% to 2.51% (0.74% ± 0.63%). CONCLUSION: Herein, we introduce a novel, noninvasive, quantitative technique utilizing anterior segment OCT images to quantitatively assess the depth and cross-sectional area of CXL in the corneal stroma based on digital image analysis. Mean cross-sectional area showing evidence of CXL was 3.46% ± 1.92% of a 6 mm long segment.

Digital analysis of flap parameter accuracy and objective assessment of opaque bubble layer in femtosecond laser-assisted LASIK: a novel technique.

BACKGROUND: The purpose of this study was to determine flap parameter accuracy, extent of the opaque bubble layer, and incidence of skip lines in femtosecond laser-assisted stromal in situ keratomileusis (LASIK) using the WaveLight(®) FS200 laser and optoelectronic clinical measurements. METHODS: Images from 101 flaps were automatically recorded during consecutive routine LASIK procedures performed using the WaveLight FS200 femtosecond laser and the EX500 excimer laser. Digital processing of these images was used to evaluate objectively the diameter of FS200-created flaps, by comparing planned versus achieved procedures and to evaluate the incidence and extent (area) of the opaque bubble layer. RESULTS: The intended flap diameters were between 8.00 mm and 9.50 mm. The achieved flap diameters showed extremely high precision, and were on average -0.16 ± 0.04 mm smaller for a 8.00 mm intended flap diameter, -0.12 ± 0.03 mm smaller for a 8.50 mm flap, and up +0.06 ± 0.06 mm wider for a 9.50 mm flap. With an average flap area of 72.4 mm(2), the mean area of the opaque bubble layer (4.1 ± 4.3 [range 0-14.34] mm(2)) corresponded to a 6% opaque bubble layer-to-flap area. Specifically, 80% of the femtosecond-created flaps had an essentially zero opaque bubble layer (<2.7% of the flap area). CONCLUSION: In our clinical experience, flaps created using FS200 and this novel highly objective assessment technique demonstrate both precision and reproducibility. The incidence of opaque bubble layer was minimal.

Correlation between central corneal thickness, anterior chamber depth, and corneal keratometry as measured by Oculyzer II and WaveLight OB820 in preoperative cataract surgery patients.

PURPOSE: To compare and correlate central corneal thickness (CCT), anterior chamber depth (ACD), and keratometric (flat and steep K) measurements using two anterior segment imaging methods, a Scheimpflug camera system (Oculyzer II [Oculus Optikgeräte GmbH]) and a partial coherence biometry system (WaveLight OB820 [Alcon Laboratories Inc]) in eyes undergoing cataract surgery. METHODS: Ninety patients (mean age: 66±13 years [range: 32 to 88 years]) underwent preoperative measurement of CCT, ACD, and keratometric measurements by Scheimpflug tomography (Oculyzer II) and optical low coherence reflectometry (WaveLight OB820). Interdevice agreement and correlation between the two techniques were assessed. RESULTS: All measurements were highly correlated and showed no clinically significant difference between methods. Mean CCT was 554.21±39.07 µm and 546.59±37.75 µm for the Oculyzer II and WaveLight OB820, respectively (R²=0.9268). Mean ACD was 2.63±0.44 mm and 2.63±0.43 mm for the Oculyzer II and WaveLight OB820, respectively (R(2)=0.9488). The principal meridian keratometric values were also highly correlated. Mean flat K was 42.88±1.50 diopters (D) and 42.96±1.40 D for the Oculyzer II and WaveLight OB820, respectively (R²=0.8741). Mean steep K was 44.08±1.79 D and 44.26±1.95 D for the Oculyzer II and WaveLight OB820, respectively (R(2)=0.9159). CONCLUSIONS: Our data show that the Oculyzer II and WaveLight OB820 provide measurements that are in agreement with published values for CCT and ACD in patients. Excellent agreement for CCT and ACD was found between the two devices, as demonstrated by a high degree of correlation and linearity, in addition to minimal bias. Thus, CCT, ACD, and K measurements by these instruments can both be used in clinical preparation, and their agreement is an ensuring precision factor for cataract and refractive surgeons.

Stability of simultaneous topography-guided photorefractive keratectomy and riboflavin/UVA cross-linking for progressive keratoconus: case reports.

PURPOSE: To follow the stability of a simultaneously delivered therapy that corrects aberrations and stiffens the corneal collagen of eyes with progressive keratoconus. METHODS: Two patients with progressive keratoconus underwent partial treatment (70% cylinder and sphere up to 50-µm central depth) with topographic customized photorefractive keratectomy (PRK) using the T-CAT module of the ALLEGRETTO WAVE Eye-Q excimer laser (Alcon Laboratories Inc), and then immediate corneal collagen cross-linking (CXL) with riboflavin 0.1% drops every 2 minutes while exposed to mean 365-nm ultraviolet A (UVA) light at 3.0 mW/cm² for 30 minutes (the Athens Protocol). Pre- and postoperative evaluations included manifest and cycloplegic refraction, Scheimpflug corneal tomography and pachymetry, and slit-lamp examination of corneal clarity with a minimum follow-up of 30 months. RESULTS: Both treated eyes experienced rapid healing of the epithelial surface within 5 days and progressive improvement of vision. In the first case, partial treatment reduced the astigmatism and aberrations, allowing for successful soft contact lens wear at 3 months. Follow-up at 13, 19, 30, and 36 months showed progressive reduction of refractive myopia and keratometric power. In the second case, laser treatment led to a near emmetropic refraction with an uncorrected visual acuity of 20/20 at 3 months, which remained unchanged at 21 and 30 months postoperative. CONCLUSIONS: Partial topography-guided PRK followed by riboflavin/UVA CXL is a safe and effective therapy that halts the progression of keratoectasia and reduces the spherocylindrical refraction and aberrations to improve the visual function of patients with progressive keratoconus. Stability and progressive improvement over time is observed, although limitations may exist for steeper and thinner corneas.

Staged intrastromal delivery of riboflavin with UVA cross-linking in advanced bullous keratopathy: laboratory investigation and first clinical case.

PURPOSE: To evaluate the safety and efficacy of staged ultraviolet A (UVA) cross-linking following intrastromal 0.1% riboflavin administration in eyes with advanced corneal edema. METHODS: Ten eye bank corneas divided in two groups (n = 5) were placed on a pressurized artificial anterior chamber following Descemet's membrane stripping. Two consecutive corneal pockets (350- and 150-microm depth) were sequentially created using a femtosecond laser. Sequential intrastromal injections of 0.1% riboflavin (0.2 mL) followed by either UVA irradiation (15 mW/cm2) for 7 minutes or exposure to air were performed for each pocket. Corneal clarity and central thickness were measured before and after the two UVA cross-linking steps. The same steps were clinically applied in an 84-year-old woman with bullous keratopathy prior to corneal transplantation and followed for 6 months. RESULTS: The corneal clarity improved in the treated but not the control eyes. The mean central corneal thickness was significantly reduced by 256 microm (ultrasound, P = .0002) and 273 miccrom (Scheimpflug, P = .0004) in treated eyes, but only 100 microm (ultrasound, P = .048) and 107 microm (Scheimpflug, P = .075) in the control eyes. The clinical treatment of corneal edema showed improved clarity and reduced central corneal thickness from 675 to 550 microm (ultrasound) and 696 to 571 microm (Scheimpflug) at 1 month. Best spectacle-corrected visual acuity improved from finger counting to 20/80 at 1 week and beyond, postponing corneal transplantation for > 6 months. CONCLUSIONS: Staged UVA cross-linking (15 mW/cm2) with femtosecond laser facilitated intrastromal 0.1% riboflavin administration may be a safe (no corneal scarring) and effective (marked reduction of edema) temporizing alternative method for managing bullous keratopathy.