Argyro D. Plaka

Femtosecond laser technology in corneal refractive surgery: a review.

PURPOSE To discuss current applications and advantages of femtosecond laser technology over traditional manual techniques and related unique complications in corneal refractive surgical procedures, including LASIK flap creation, intracorneal ring segment implantation, astigmatic keratotomy, presbyopic treatments, and intrastromal lenticule procedures. METHODS Literature review. RESULTS From its first clinical use in 2001 for LASIK flap creation, femtosecond lasers have steadily made a place as the dominant flap-making technology worldwide. Newer applications are being evaluated and are increasing in their frequency of use. CONCLUSIONS Femtosecond laser technology is rapidly becoming a heavily utilized tool in corneal refractive surgical procedures due to its reproducibility, safety, precision, and versatility.

Corneal stroma demarcation line after standard and high-intensity collagen crosslinking determined with anterior segment optical coherence tomography

Purpose To use anterior segment optical coherence tomography (AS‐OCT) to compare corneal stroma demarcation line depth after corneal collagen crosslinking (CXL) with 2 treatment protocols. Setting Vardinoyiannion Eye Institute of Crete, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece. Design Prospective comparative interventional case series. Methods Corneal collagen crosslinking was performed in all eyes using the same ultraviolet‐A (UVA) irradiation device (CCL‐365). Eyes were treated for 30 minutes with 3 mW/cm2 according to the standard Dresden protocol (Group 1) or for 10 minutes with 9 mW/cm2 of UVA irradiation intensity (Group 2). One month postoperatively, 2 independent observers measured the corneal stroma demarcation line using AS‐OCT. Results Sixteen patients (21 eyes) were enrolled. Group 1 comprised 7 patients (9 eyes) and Group 2, 9 patients (12 eyes). The mean corneal stroma demarcation line depth was 350.78 &mgr;m ± 49.34 (SD) (range 256.5 to 410 &mgr;m) in Group 1 and 288.46 ± 42.37 &mgr;m (range 238.5 to 353.5 &mgr;m) in Group 2; the corneal stroma demarcation line was statistically significantly deeper in Group 1 than in Group 2 (P=.0058, t test for unpaired data). Conclusion The corneal stroma demarcation line was significantly deeper after a 30‐minute CXL treatment than after a 10‐minute CXL procedure with high‐intensity UVA irradiation. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Correlation of the Corneal Collagen Cross-Linking Demarcation Line Using Confocal Microscopy and Anterior Segment Optical Coherence Tomography in Keratoconic Patients

PURPOSE To evaluate and compare the depth of the corneal stromal demarcation line after corneal collagen cross-linking (CXL) using 2 different methods: confocal microscopy and anterior segment optical coherence tomography (AS OCT). DESIGN Prospective, comparative, interventional case series. METHODS Seventeen patients (18 eyes) with progressive keratoconus were enrolled. All patients underwent uneventful CXL treatment according to the Dresden protocol. One month after surgery, corneal stromal demarcation line depth was measured in all patients by 2 independent observers using confocal microscopy and AS OCT. RESULTS Mean corneal stromal demarcation line depth measured using confocal microscopy by the first observer was 306.22 ± 51.54 μm (range, 245 to 417 μm) and that measured by the second observer was 303.5 ± 46.98 μm (range, 240 to 390 μm). The same measurements using AS OCT were 300.67 ± 41.56 μm (range, 240 to 385 μm) and 295.72 ± 41.01 μm (range, 228 to 380 μm) for the first and second observer, respectively. Pairwise comparisons did not reveal any statistically significant difference between confocal microscopy and AS OCT measurements for both observers (P = .3219 for the first observer and P = .1731 for the second observer). CONCLUSIONS Both confocal microscopy and AS OCT have similar results in evaluating the depth of the corneal stromal demarcation line after CXL.

Topography-guided Transepithelial PRK After Intracorneal Ring Segments Implantation and Corneal Collagen CXL in a Three-Step Procedure for Keratoconus

PURPOSE To present the results of topography-guided transepithelial photorefractive keratectomy (PRK) after intracorneal ring segments implantation followed by corneal collagen cross-linking (CXL) for keratoconus. METHODS In this prospective case series, 10 patients (16 eyes) with progressive keratoconus were included. All patients underwent topography-guided transepithelial PRK after Keraring intracorneal ring segments (Mediphacos Ltda) implantation, followed by CXL treatment. The follow-up period was 6 months after the last procedure for all patients. Time interval between both intracorneal ring segments implantation and CXL and between CXL and topography-guided transepithelial PRK was 6 months. RESULTS LogMAR mean uncorrected distance visual acuity and mean corrected distance visual acuity were significantly improved (P<.05) from 1.14±0.36 and 0.75±0.24 preoperatively to 0.25±0.13 and 0.13±0.06 after the completion of the three-step procedure, respectively. Mean spherical equivalent refraction was significantly reduced (P<.05) from -5.66±5.63 diopters (D) preoperatively to -0.98±2.21 D after the three-step procedure. Mean steep and flat keratometry values were significantly reduced (P<.05) from 54.65±5.80 D and 47.80±3.97 D preoperatively to 45.99±3.12 D and 44.69±3.19 D after the three-step procedure, respectively. CONCLUSIONS Combined topography-guided transepithelial PRK with intracorneal ring segments implantation and CXL in a three-step procedure seems to be an effective, promising treatment sequence offering patients a functional visual acuity and ceasing progression of the ectatic disorder. A longer follow-up and larger case series are necessary to thoroughly evaluate safety, stability, and efficacy of this innovative procedure.

Evaluation of the corneal collagen cross-linking demarcation line profile using anterior segment optical coherence tomography.

Purpose: To evaluate the depth of the stromal demarcation line after corneal collagen cross-linking (CXL) using anterior segment optical coherence tomography. Methods: In this prospective, interventional case series, 23 patients (27 eyes) with progressive keratoconus were enrolled. All patients underwent uneventful CXL treatment. Corneal stromal demarcation line depth was measured centrally, 3 mm temporally, and 3 mm nasally by 2 independent observers using anterior segment optical coherence tomography at 1 month postoperatively in all patients. Results: Mean depth of the corneal stromal demarcation line measured by the first observer was 310.67 ± 31.04 &mgr;m (range, 258–364 &mgr;m) centrally, 212.07 ± 24.5 &mgr;m (range, 178–279 &mgr;m) nasally, and 218.04 ± 21.91 &mgr;m (range, 191–261 &mgr;m) temporally. Mean depth of the corneal stromal demarcation line measured by the second observer was 308.78 ± 29 &mgr;m (range, 262–381 &mgr;m) centrally, 211.04 ± 23.93 &mgr;m (range, 180–277 &mgr;m) nasally, and 217.22 ± 25.51 &mgr;m (range, 179–271 &mgr;m) temporally. There was a statistically significant difference (P < 0.001) between central and both nasal and temporal depths of the corneal stromal demarcation line (paired samples t test) for both observers. There was no statistically significant difference between nasal and temporal corneal stromal demarcation line depths (paired samples t test, P > 0.05) for each observer. Conclusions: Mean depth of the corneal stromal demarcation line after CXL treatment is greater centrally in comparison with nasal and temporal depths.

Simultaneous Conventional Photorefractive Keratectomy and Corneal Collagen Cross-linking for Pellucid Marginal Corneal Degeneration

PURPOSE To present the results after simultaneous conventional photorefractive keratectomy combined with corneal collagen cross-linking for pellucid marginal corneal degeneration. METHODS In this prospective, interventional case series, 6 patients (8 eyes) with pellucid marginal corneal degeneration were enrolled. All patients underwent simultaneous conventional photorefractive keratectomy combined with corneal collagen cross-linking; corneal epithelium was removed by transepithelial phototherapeutic keratectomy during treatment (Cretan protocol plus conventional photorefractive keratectomy). Visual and refractive outcomes were evaluated along with endothelial cell density preoperatively and at 1, 3, 6, and 12 months postoperatively. RESULTS No intraoperative or postoperative complications were observed in any of the patients. LogMAR mean uncorrected distance visual acuity improved significantly from 1.05 ± 0.33 preoperatively to 0.41 ± 0.27 (P = .018) at 12 months postoperatively. Mean corrected distance visual acuity did not change significantly (P > .05) postoperatively. Mean spherical equivalent improved significantly from -3.52 ± 2.29 diopters preoperatively to -1.57 ± 1.76 diopters (P = .028) at last follow-up. Mean corneal astigmatism was significantly reduced from -6.83 ± 2.33 diopters preoperatively to -4.71 ± 1.89 diopters (P = .018) at the last follow-up. No endothelial cell density alterations were observed throughout the follow-up period (P > .05). CONCLUSIONS Simultaneous conventional photorefractive keratectomy combined with corneal collagen cross-linking seems to be an effective, safe, and promising treatment for the management of pellucid marginal corneal degeneration.

Treatment of corneal dellen with a large diameter soft contact lens

A 58-year-old man presented with corneal dellen twelve days after pterygium removal on his left eye. Initial treatment with lubrication and artificial tears was unsuccessful. The fitting of a conventional contact lens was not possible because of conjuctival chemosis. Additionally the patient denied eye patching due to professional reasons. As an alternative treatment a large diameter bandage soft contact lens approved for extended wear was applied ((David Thomas Contact Lens T74/85 Extended Wear/Bandage of 18mm diameter). The next day corneal dellen had already began to retreat and four days later the contact lens was removed since there was no sign of dellen in the slit lamp examination. In conclusion, the use of a large diameter soft contact lens was an effective alternative solution for the treatment of corneal dellen in our patient.

Femtosecond Laser-Assisted Intra-Corneal Drug Delivery

Abstract Purpose: To present a case of fungal keratitis that was successfully treated with direct intrastromal medication delivery through a corneal incision created with the femtosecond laser. Methods: A 71-year-old female patient with recurrent episodes of an unresponsive, deep stromal keratitis for six months’ duration, resistant to various therapeutic approaches, was referred to our institute. The 150 kHz Intralase iFS laser (Abbott Medical Optics Inc., Santa Ana, CA) was used to create a corneal pocket in an attempt to permit drug delivery directly into the corneal abscess. Results: Five days after the intrastromal injections, the clinical condition was improved. Two years after the procedure, the cornea is stable and free of any clinical signs or symptoms of recurrence. Conclusions: In this case report, an alternative application of femtosecond laser technology is presented, performing intrastromal drug delivery through a corneal incision for the treatment of fungal keratitis.

Interface lamellar keratitis induced by a post-Descemet stripping automated endothelial keratoplasty corneal trauma.

A 78-year-old female patient suffering from Fuchs endothelial dystrophy had uneventful Descemet stripping automated endothelial keratoplasty (DSAEK) on the right eye. One and a half months postoperatively, she underwent a corneal foreign body trauma and was referred to our clinic, complaining about vision deterioration. Slit-lamp examination revealed a severe and diffuse interface lamellar keratitis between the DSAEK graft and the recipients cornea without any signs of graft dysfunction. Intensive treatment with local corticosteroids was applied immediately, resulting in prompt improvement of both visual acuity and clinical condition. A new clinical entity, described as interface lamellar keratitis after corneal trauma in a DSAEK patient, is presented. Early diagnosis and appropriate intensive treatment with local corticosteroids are essential to successfully address this uncommon post-DSAEK complication.

Ocular biomarkers in diseases and toxicities

Research is ongoing in the field of identification of molecular biomarkers concerning ophthalmology. Such molecules may be helpful in early detection of a disease, predicting the severity of a disease and the rate of disease progression, and also monitoring response to treatment. In this chapter we focus on molecular biomarkers that are involved in the diagnosis and management of several ocular pathologies, as well as in ocular toxicity deriving from agents prescribed for other systemic conditions. Such toxicity may be observed in variable forms deriving from several agents. The fields of ocular disease that have been most studied for identification of biomarkers are ocular surface disease, keratoconus, glaucoma, ocular malignancies, and retinal disease. Several molecules have been identified regarding all these entities. Other than identification, quantification of biomarkers under standardized conditions is the target in order to achieve clinical utility.