Ugur Celik

Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: A prospective fellow eye study

PURPOSE To compare corneal hysteresis (CH) and corneal resistance factor (CRF) between eyes treated with small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK). SETTING Beyoğlu Eye Training and Research Hospital. DESIGN Prospective comparative case series. METHODS Sixty eyes from 30 patients with bilateral myopia or myopic astigmatism were studied. Inclusion criteria were spherical equivalent of subjective manifest refraction (SE) <10diopters (D) and a difference ≤0.50D between the SEs of both eyes. One eye of each patient was treated with SMILE, and the fellow eye underwent femto-LASIK. Randomization was performed using a sealed envelope system. The main outcome measures were CH and CRF measured preoperatively and postoperatively (1 and 6 months). RESULTS Preoperative SE was similar in both groups (p=0.852). CH and CRF values were reduced postoperatively in both groups compared to their corresponding preoperative values (p<0.001). At the 6-month follow-up visit, the mean CH values in the SMILE and femto-LASIK groups were 8.95±1.47 and 9.02±1.27, respectively (p=0.852), and the mean CRF values were 7.77±1.37 and 8.07±1.26, respectively (p=0.380). CONCLUSION CH and CRF decreased after SMILE. There were no differences between SMILE and femto-LASIK treatments in postoperative CH or CRF values.

Comparing the Effects of Three Different Intravitreal Injection Techniques on Vitreous Reflux and Intraocular Pressure

PURPOSE To compare the effects of straight, oblique, and double-plane tunnel scleral intravitreal injection techniques, on short-term intraocular pressure (IOP) changes, occurrence of vitreous reflux (VR), and/or other complications. METHODS A total of 105 patients were included in this prospective study. Patients were assigned randomly to one of the straight injection group (SI; n=35), oblique injection group (OI; n=35), or double-plane tunnel injection group (DPTI; n=35). The occurrence of VR and preinjection and postinjection IOP at 2 and 6 h were compared between groups, and complications were assessed. RESULTS The mean patient age was 71.1±6.6 years (range 58 to 86 years; 50 women and 55 men). In the SI, OI, and DPTI groups, VR occurred in 18 (51.4%), 12 (34.3%), and 6 patients (17.1%), respectively. Mean preinjection IOPs were 15.4, 14.8, and 15.6 mmHg, and changed to 17.3, 18.0, and 20.0 mmHg at the second hour, and 15.7, 16.2, and 16.1 mmHg at the sixth hour, respectively. No significant differences among the groups were found in terms of complications such as transient mild uveitis or subconjunctival hemorrhage. CONCLUSION Double-plane tunnel injection prevents VR from the injection site and has no additional complications than other techniques.

Corneal Biomechanical Comparison of Pseudoexfoliation Syndrome, Pseudoexfoliative Glaucoma and Healthy Subjects

Abstract Purpose: To evaluate the differences in corneal biomechanical properties between healthy subjects and patients with pseudoexfoliation syndrome (PEX) and pseudoexfoliative glaucoma (PEXG) using the ocular response analyzer (ORA). Materials and methods: One hundred eighteen eyes of 45 healthy, 43 PEX and 30 PEXG eyes were included in to the study. Corneal biomechanical parameters measurements were obtained using ORA. The main parameters assessed were corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated pressure measurement (IOPg) and corneal compensated intraocular pressure (IOPcc). Ultrasound pachymetry was used for measurement of central corneal thickness (CCT). Results: In healthy subjects, PEX and PEXG eyes’ mean CH values were 10.3 ± 1.4, 8.2 ± 1.4 and 6.8 ± 1.7 mmHg, respectively. The difference in mean CH between the PEXG and other two groups were statistically significant (p < 0.001). Mean CRF values were 10.3 ± 0.7, 7.9 ± 1.6 and 7.9 ± 1.9 mmHg, in healthy subjects PEX and PEXG, respectively. The difference in mean CRF between the PEX and PEXG was not statistically significant (p = 0.630), however the mean CRF was significantly higher in healthy subjects, compared to other two groups. Mean CCT were 546.3 ± 28, 525.5 ± 35 and 509 ± 36 μ, in healthy subjects, PEX and PEXG, respectively. The differences on CCT were also significant among the three groups (p < 0.001). Conclusion: In this study, the corneal biomechanical features of subjects with PEX were found to be changed as compared to healthy controls. In these patients; CH, CRF and CCT were decreased which was more obvious in patients with PEXG in comparison to PEX patients.

Subfoveal choroidal thickness measurements with enhanced depth imaging optical coherence tomography in patients with nanophthalmos

Purpose To compare subfoveal choroidal thickness (SFCT) between patients with nanophthalmos and age-matched controls. Methods This prospective, cross-sectional and comparative study included 31 eyes from 31 patients with nanophthalmos (study group) and 31 eyes from 31 healthy subjects (control group). SFCT and central macular thickness (CMT) were measured with spectral domain optical coherence tomography. All participants underwent a standardised ocular examination including best corrected visual acuity (BCVA), central corneal thickness (CCT), anterior chamber depth (ACD) and refractive error (RE) measurements. Results Mean SFCT in the nanophthalmic eyes and in the control eyes were 551.3±87 µm and 330.5±46 µm, respectively (p<0.001). Mean BCVA, RE, CMT, axial length (AL), ACD, CCT values were 0.4±0.28 logMAR Unit, +10.6 (3.06), 331.9±78 µm, 18.8±1.5 mm, 2.42±0.4 mm and 577.2±32 µm, respectively, in nanophthalmic eyes and there was a statistically significant difference between groups (p<0.001 for each). There were negative correlations between SFCT with AL (r=−0.836, p<0.001) and ACD (r=−0.597, p<0.001) for the entire study population. SFCT was significantly correlated with CCT (r=0.471, p<0.001) and CMT (r=0.585, p<0.001), RE (r=0.836, p<0.001). Conclusions SFCT was significantly higher in nanophthalmic eyes. Further studies are needed to evaluate the role of SFCT to explain the pathophysiology of nanophthalmos.

Pain, wound healing and refractive comparison of mechanical and transepithelial debridement in photorefractive keratectomy for myopia: results of 1 year follow-up.

PURPOSE To compare the efficacy, safety and postoperative pain of mechanical versus transepithelial photorefractive keratectomy (PRK) techniques. SETTING Cornea and refractive surgery subspecialty. DESIGN Prospective clinical trial. METHODS This prospective comparative study included 84 eyes of 42 patients with myopia who received mechanical PRK (m-PRK) in 1 eye and transepithelial PRK (t-PRK) in the contralateral eye. The mean patient age was 28.5±6.3 years (range 20-46 years). Postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractions, postoperative epithelial healing time, surgical time, postoperative pain rating and corneal haze were recorded. RESULTS At week 1, statistically the UDVA was significantly better in the t-PRK eyes; however, at 3 months, similar refractive stability was achieved in both groups. The mean spherical equivalent (SE) decreased from -2.44±1.00D (m-PRK eyes) and -2.88±1.24D (t-PRK eyes) at baseline to -0.19±0.38D and -0.30±0.40D, respectively, after 1 year. Surgical time was 98.6±9.8s in m-PRK eyes and 58.0±6.4s in t-PRK eyes. On postoperative days 1 and 3, using the global assessment rating, 81% of mPRK eyes that had pain, reported more pain than that reported for the tPRK eyes. In addition, m-PRK treated eyes demonstrated higher mean pain scores based on the 11-point numerical rating scale and Visual Analogue Scale (VAS). The mean time to complete epithelial healing was 2.19±0.39 days (t-PRK) and 3.76±0.43 days (m-PRK). CONCLUSION t-PRK for mild-to-moderate myopia was more comfortable than conventional m-PRK; patients had less pain, and faster healing time.

Femtosecond lenticule extraction for correction of myopia: a 6 month follow-up study.

Aims To report our initial experience with femtosecond lenticule extraction (FLEX) compared with femtosecond laser-assisted in situ keratomileusis (LASIK). Settings and design This was a prospective pilot study carried out at the Refractive Surgery Department of the Beyoglu Eye Training and Research Hospital, Istanbul, Turkey. Materials and methods Surgery was performed on both eyes of 14 consecutive patients with myopia or myopic astigmatism. Patients underwent FLEX in one eye and femtosecond LASIK (FemtoLASIK) in the other eye. The primary outcome was based on uncorrected distance visual acuity, corrected distance visual acuity, and spherical equivalent of the subjective manifest refraction, at 1 week, 1 month, and 6 months postsurgery. Statistical analyses were performed using PAWS Statistics 18. Unpaired Student’s t-test was used to compare the groups. Results During the last follow-up visit (6 months postsurgery), the mean spherical was −0.37 ± 0.60 diopters (D) (range −1.00 to 0.50) (P < 0.001) and −0.25 ± 0.41 D (range −0.88 to 0.12 D) (P < 0.001) in the FLEX and FemtoLASIK eyes, respectively. The spherical was within ± 0.50 D of the intended correction in ten (72%) of the FLEX eyes and 12 (86%) of the FemtoLASIK eyes (P > 0.05). No complications occurred during surgery or the postoperative period. Conclusion FLEX is a safe, effective, and predictable procedure for surgical correction of myopia. Refractive results were stabilized within the first postoperative week, and visual acuities were stabilized within the first month, comparable to FemtoLASIK.

Evaluation of subbasal nerve morphology and corneal sensation after accelerated corneal collagen cross-linking treatment on keratoconus.

Abstract Purpose: The aim of this study was to report on the evaluation of corneal nerve fiber density and corneal sensation after accelerated corneal collagen cross-linking on keratoconus patients. Methods: The study was performed on 30 keratoconus eyes (30 participants: 16 M, 14 F; 17–32 years old) treated with accelerated collagen cross-linking for disease stabilization. Mean outcome measures were corneal sensation evaluation by Cochet–Bonnet esthesiometry and subbasal nerve fiber density assessment by corneal in vivo confocal microscopy. All corneal measurements were performed using scanning slit confocal microscopy (ConfoScan 4, Nidek Technologies, Padova, Italy). Results: The accelerated corneal collagen cross-linking procedure was performed on 30 eyes of 30 patients (19 right, 63.3%; 11 left, 27.7%). The mean age was 23.93 ± 4. The preoperative mean keratometry, apex keratometry and pachymetry values were 47.19 ± 2.82 D, 56.79 ± 5.39 and 426.1 ± 25.6 μm, respectively. Preoperative mean corneal sensation was 56.3 ± 5.4 mm (with a range from 40 to 60 mm), it was significantly decreased at 1st and 3rd month visit and increased to preoperative values after 6th month visit. Preoperative mean of subbasal nerve fiber density measurements was 22.8 ± 9.7 nerve fiber/mm2 (with a range of 5–45 mm), it was not still at the preoperative values at 6th month (p = 0.0001), however reached to the preoperative values at 12th month (p = 0.914). Conclusions: Subbasal nerve fibers could reach the preoperative values at the 12th month after accelerated corneal collagen cross-linking treatment although the corneal sensation was improved at 6th month. These findings imply that the subjective healing process is faster than the objective evaluation of the keratoconus patients’ cornea treated with accelerated corneal collagen cross-linking.

Surgical therapy versus observation for lamellar macular hole: a retrospective comparison study.

Background The purpose of this study was to compare anatomic and visual changes in patients with lamellar macular hole undergoing pars plana vitrectomy with those in patients undergoing follow-up only. Methods In this retrospective consecutive case series study, we evaluated two groups of eyes, comprising 19 eyes from 19 patients with lamellar macular hole who underwent pars plana vitrectomy with internal limiting membrane peeling and 21 eyes from 21 patients with lamellar macular hole who had follow-up only. Corrected distance visual acuity (CDVA, in logMAR) and optical coherence tomography findings, including measurements of maximum diameter of lamellar defect and foveal thickness, and whether the inner segment/outer segment band was intact or not were documented at initial and follow-up examinations. Results At initial examination, mean CDVA was 0.54 logMAR in the study group and 0.51 logMAR in the control group, and 0.33 logMAR and 0.55 logMAR, respectively, on final examination. In the study group, postoperative optical coherence tomography images were found to be normalized in ten patients (52.6%), improved in six (31.5%), unchanged in two (10.5%), and to have progressed to full-thickness macular hole in one (5.2%) in the intervention group, while all patients in the control group were found to have deteriorated within the follow-up period between March 2004 and June 2010. Conclusion In patients with lamellar macular hole, combination treatment with pars plana vitrectomy and internal limiting membrane peeling appears to be effective, but further studies are required to establish new treatment modalities for patients who do not have a satisfactory outcome from treatment.

INTRAVITREAL BEVACIZUMAB IN THE TREATMENT OF CHOROIDAL NEOVASCULAR MEMBRANE DUE TO ANGIOID STREAKS.

Purpose: To investigate the results of intravitreal bevacizumab for choroidal neovascularization (CNV) secondary to angioid streaks and to assess the factors influencing disease progression. Methods: Patients treated with intravitreal bevacizumab (1.25 mg/0.05 mL) for CNV secondary to angioid streaks were reviewed retrospectively. In addition to demographic findings, ophthalmologic findings at baseline and during follow-ups were recorded. Results: Twenty-three eyes of 20 patients (mean age, 45.7 years; 7 women) were included in the study. Mean follow-up was 23 months. Mean number of injections was 5.1. Initial and final logMAR visual acuity was not different (0.53 ± 0.33 and 0.60 ± 0.40 logMAR, P = 0.79). At the last examination, patients with final active CNV (N = 14) were younger (mean age, 42 years) than patients with final inactive CNV (N = 9) (mean age, 52 years). The former group required higher number of injections (6.6 vs. 2.8, P = 0.013). Eyes with pseudoxanthoma elasticum (N = 10) needed injections every 4.4 months while the others (N = 13) every 7.2 months (P = 0.072). Pseudoxanthoma elasticum positivity ended up with active membranes in 70% of the cases, composing half of the overall final active CNVs in this study. Conclusion: Intravitreal bevacizumab stabilized vision in eyes with CNV and angioid streaks. At younger ages, CNV behaved more aggressively and seemed to be more resistant to treatment.

Plateletcrit in Ocular Pseudoexfoliation Syndrome.

Purpose: The aim of this study was to compare all platelet markers, especially plateletcrit (PCT, total platelet mass), in patients with and without ocular pseudoexfoliation (PEX) syndrome. Methods: One hundred six patients with ocular PEX syndrome (study group) and 106 individuals without ocular PEX syndrome (control group) were enrolled in this retrospective case-control study. The biochemical/hematological laboratory results of both the study and control groups were analyzed by a clinician blinded to the group assignments. The main outcome measures were the PCT, platelet count (PLT), mean platelet volume (MPV), and platelet distribution width (PDW). Results: The mean PCT in the study and control groups were 0.206%±0.520% and 0.171%±0.410%, respectively (P<0.001), and the mean PDW in the study and control groups were 16.12%±1.21% and 14.68%±1.40%, respectively (P<0.001). There were no differences in the MPV or mean PLT (P=0.138 and P=0.055, respectively). The PCT cutoff value was 0.180 (area under the receiver operating characteristics curve, 0.706; P<0.001; 65% sensitivity; 74% specificity). Conclusions: The PCT and PDW were significantly higher in patients with than without ocular PEX syndrome. These increased parameters may cause microvascular blood flow resistance and the heightened inflammatory response caused by excessive platelet activity, as with other cardiovascular diseases, and may also decrease aqueous humor outflow in ocular PEX syndrome.